The three-phase grid-connected inverters are widely employed in various distributed generation (DG) applications. The use of LCL filters at their outputs has proven several benefits, regarding passive component size reduction and improved high-frequency harmonics elimination. However, the resonance of the LCL filter hinders their application. Another issue with applying model predictive control (MPC) in LCL-filter-based DGs, as a high-performance controller, is the difficulty in including the various control objectives in a single cost function. The main issues include the necessity to compensate for various delays in the control loops and the selection of a proper weighting factor between objectives. Therefore, this paper proposes an efficient MPC method for grid-connected LCL-filtered DG inverters. The proposed MPC employs proper delay compensation for current/voltage loops. Furthermore, the proposed method incorporates various controlled variables in a single-objective function, eliminating the need for cascaded control loops. The proposed MPC is simulated in MATLAB/Simulink, and different test cases of active/reactive power demands are provided. The obtained results show the robust resonance-free performance of the proposed MPC method.

This paper presents a comparative study of modulation strategies for a full-bridge based unidirectional step-down partial power converter (PPC), focusing on a newly proposed Buck Modulation (BM) scheme. Unlike traditional Phase-Shift Modulation (PSM), BM disables transformer utilization by applying identical PWM signals to all switches in the converter’s full-bridge, effectively converting the topology into an equivalent buck converter. Thermal simulations were conducted to evaluate efficiency performance across different transformer turns ratios and load conditions. Results demonstrate that BM achieves superior efficiency at light loads when the transformer ratio is below unity, and consistently outperforms PSM across the entire power range when the ratio exceeds unity. Furthermore, BM offers a wider and more flexible operating voltage range.

On-board integrated battery chargers (OIBCs) have gained considerable attention due to their low volume and weight, achieved by employing the traction drive converter as the on-board charging unit. This approach eliminates the need for additional hardware, such as extra semiconductor switches or passive filter components. In this paper, a novel OIBC based on the open-winding motor (OWM) drive is introduced. The proposed OIBC configuration is designed for single-phase power grids, making it particularly suitable for direct residential charging with household power without the need for additional conversion stages. The dual-inverter-fed OWM drive transforms into a power factor correction (PFC) converter and a two-phase interleaved buck converter during charging. Due to using the interleaved structure, the proposed OIBC supports fast-charging functionality, which reduces overall charging times. This paper applies the finite control-set model predictive control (FCS-MPC) along with a disturbance observer-based (DOB) method for the currents and voltages of both PFC and interleaved converters. This integration removes the need for a separate control board or a dedicated charging control algorithm. The validation of the proposed OIBC configuration and the MPC methodology is performed in MATLAB/Simulink software.

Photovoltaic (PV) grid-connected system is nowa-days a well established industry. For PV inverters, European (EURO) efficiency and California Energy Commission (CEC) efficiency have been defined, as Figures of Merit (FoM) allowing easy PV inverter efficiency estimation, while including consideration on PV variability. This paper explores the applicability of weighted efficiencies for off-grid H2production system with DC-DC connection of the PV source, for both DC-DC converter, and electrolyzer. The study considers precise modeling of the system, and evaluation of its operation and efficiency over real scenario, with environmental data of three locations considered, with minute-based resolution, allowing precise simulation. Evaluation of EURO and CEC efficiencies for DC-DC converter and electrolyzer demonstrate the accuracy of the FoM with error lower than 1.23% and 3.70% respectively. It is finally recommended the use of weighted efficiencies for the evaluation of off-grid H2production systems, allowing fast and accurate comparison between different electrolyzer and DC-DC converter technologies while designing new plants.

This paper presents a Continuous Control Set Model Predictive Control (CCS-MPC) enhanced with Nestorov Accelerated Gradient (NAG) for real-time closed-loop control of Cascaded H-Bridge (CHB) converters under normal operation and with faults on the power cells. The proposed method addresses limitations of conventional Finite Control Set MPC (FCS-MPC), including variable switching frequency and the computational burden for the control of multilevel converters. The main contributions of the proposed CCS-MPC with NAG are: (i) derivation of a dynamic model that enables simultaneous control of line currents and common-mode voltages under normal and fault conditions; (ii) formulation of the CCS-MPC problem as a convex, box-constrained optimization, enabling the use of an efficient projection-based solution within each NAG iteration to enforce feasibility; (iii) offline computation of matrices to minimize online computational burden; and (iv) a closed-loop reference voltage control to ensure fault-tolerant operation. The effectiveness of the proposed CCS-MPC with NAG is validated through real-time Hardware-in-the-Loop (HIL) simulations, that confirm the fast dynamic response and robust performance of the proposed algorithm under fault conditions and demonstrate its suitability for high-performance and reliable operation for industrial drives and grid-connected applications.

Robust and efficient integration of photovoltaic (PV) sources is essential for enhancing the domination of renewable sources and promoting energy transition. Recently, impedance source inverters have attracted wide interest. However, they need a high number of passive components. Thence, lower efficiency, higher cost, and bulky volume are the main drawbacks of conventional impedance source inverters. The split source-based PV inverters (SSI) have presented lower components and smaller volume candidates in these applications. Therefore, this paper presents a modified dual-input-based SSI for PV inverters. Moreover, an improved finite control set (FCS) model predictive control (MPC) method is proposed for controlling the multi-inputted PV power with their expected shading conditions. The proposed FCS-MPC also injects high quality AC current/power to the utility grid side. The proposed dual input topology and FCS-MPC are verified experimentally. The superiority of input in addition to output sides waveform qualities has been proven.

This paper presents a hybrid controller based on fractional order control (FOC) with finite control set model predictive control (FCS-MPC) for LCL grid-tied single-phase multilevel inverters. Recently, FCS-MPC has received major interest in fast control tracking and handling several control objectives together in a single cost function. However, in the case of LCL grid-tied inverters, the control of the inverter side current, grid side current, and AC filter capacitor voltage, in addition to the voltage balance of dc-link capacitors, makes the design process of a single cost function more difficult to reach. Therefore, a cascaded FOC resonant controller for grid-side current with inner FCS-MPC for controlling inverter-side current and capacitor voltages is proposed for a single-phase five-level H-bridge T-type grid-tied inverter. The proposed controller merges the characteristics of FOC, FCS-MPC, and resonant controllers, improving system performance. Simulation results are provided to verify the superior tracking and control performance of the new proposed controller.

Boost converter, as the simplest non-isolated DC-DC converter, can not provide high voltage gains. This paper proposes a non-isolated DC-DC converter with a high voltage gain. As with the boost topology, this converter provides continuity of the input current besides employing one switch with a simple drive circuit. Besides the high voltage gain, the applied voltage stresses are less than the output voltage. Notably, the highest voltage stress of the semiconductors is half of the output voltage. This converter is studied in both the ideal and non-ideal modes. Moreover, it is compared with the recently suggested converters. Finally, the experimental results are discussed. Notably, the proposed topology converts 40 V at the input source to 2500 V at the output with a 50 % switch duty cycle. The mentioned values define the proposed topology as one that can be used in power electronic base high-voltage components.

The availability of recently developed medium-voltage (MV) IGBT switch modules has made the diode-free alternative topology of three-level inverters a promising option, particularly for MV applications. Diode-free three-level-based solutions possess a smaller number of components and lower conduction losses in contrast to the diode-clamped NPC inverter. Nevertheless, some switches have to withstand half of the DC-link voltage, which still imposes restrictions on implementing a 3-level T-type inverter leg. This paper presents a reconfigured power circuit for a 3-level F-type inverter leg using a four-switch per phase-leg configuration. Compared to existing restrictions in T-type phase legs, the F-type phase leg reduces voltage stress, cost, and loss of the inverter. In this paper, an assessment is conducted to evaluate the performance and effectiveness of the F-type inverter. The investigation includes thermal analysis, switching loss, and efficiency analysis of the F-type inverter controlled by model predictive controllers. The results indicate that the F-type inverter acquires better loss distribution than the T-type inverter, revealing its usage in certain low-voltage and medium-voltage applications.

In photovoltaic (PV) systems, the adoption of the single-stage microinverters present an attractive proposition. Unlike their two-stage counterparts, which consist of separate dc-dc and dc-ac conversion stages, single-stage microinverters simplify the conversion process by integrating both functions into a single unit. This combination offers advantages in terms of size, efficiency and overall system performance. In this context, the boost inverter with bypass mode connection emerges as an attractive alternative; however control challenges arise, particularly in the non-linearities inherent in these systems. The linearization process of the converter for conventional control strategies becomes complicated, promoting the exploration of alternative control approaches. This paper proposes a predictive control scheme for a Bypass Boost Inverter (BBI), addressing the aforementioned challenges. The control strategy employs a cascaded design, where the inner loop uses Finite Control Set-Model Predictive Control (FCS-MPC) to regulate inductor currents, indirectly controlling the output current for grid connection. The proposed control scheme is validated through simulations in PLECs software, demonstrating its performance in managing a PV panel. The results show good tracking of inductor current references and compliance with the standards for grid connection.

This paper presents an improved model-free control (MFC) with a modified state observer to regulate the speed in the finite-set predictive current control (FS-PCC) of permanent magnet synchronous motor (PMSM) drives. In the proposed method, the lumped disturbance is removed from the formulations. So, the extended state observer is not required. Instead, a function of the estimation error plays the role of the lumped disturbance. In this way, a simple yet precise disturbance estimation is achieved. Furthermore, the proposed MFC utilizes a nonlinear control law instead of the regular proportional controller to track the speed reference rapidly. The inner control loop of the drive is constructed based on the model-free FS-PCC. Thus, the overall control system is independent of the classical model of the PMSM creating a fully robust predictive control. The proposed model-free speed-controlled FS-PCC (MFSC-FS-PCC) is evaluated through simulations and experiments. The results show that the proposed method has a fast dynamic response while preserving good steady-state performance.

This article presents an optimization in implementing a DTC control scheme using a 3L-NPC inverter to control the speed of a three-phase induction machine. Regarding the DTC strategy, 3 and 5-level hysteresis controllers were used to control the stator flux and electromagnetic torque, respectively. The traditional implementation of the scheme [2], shows good results regarding the motor speed response; however, the electromagnetic torque developed by the motor presents various issues: significant ripples in torque produced by a poor choice of the hysteresis controller amplitude, poor tracking of the torque reference signal in steady state, and high torque peaks in large speed steps, which translate into current peaks that exceed the motor’s thermal limit. This work proposes new strategies for adjusting the flux and electric torque hysteresis controllers, which will correct the problems presented in the traditional implementation. Finally, a comparison will be made between the modified DTC strategy and the traditional DTC strategy of [2].

Recently, doubly grounded (DG) photovoltaic (PV) inverters have proven superior performance in total elimination capability of PV leakage currents. This is due to the direct connection of PV side negative terminal with grid side neutral terminal. This paper presents a boost DG-PV five-level (5L) inverter topology based on neutral point clamped (NPC) leg. The proposed DG-PV boost 5L-NPC inverter totally eliminates the existing leakage currents, achieves boost of PV voltage, is considered a single stage PV inverter structure, uses low component count, and has continuous PV current. Moreover, finite control set model predictive control (FCS-MPC) is presented for controlling multiple objectives in a single cost function for the proposed topology. The FCS-MPC also eliminates the cascaded l0ops in the conventional control methods, which facilitates the control design process. A simulation based case study is preformed of the proposed DG-PV boost 5L-NPC inverter with FCS-MPC controller. Superiority of proposed inverter and controller have been verified with various step changes in PV power, power quality of injected grid current, and capacitor voltage control.

This article proposes an innovative control strategy for the Dual Active Bridge (DAB) power converter, enhancing the Moving Discretized Control Set - Model Predictive Control (MDCS-MPC) algorithm for voltage and current control. The proposed approach enables fast dynamic response, precise control, and no steady-state error in both voltage and current regulation. By utilizing a predictive model of the system variables, the algorithm anticipates their behavior for various actuation scenarios, while effectively managing output current perturbations. To ensure safe operation within specified limits, two current limiting methods are introduced: a dynamic current limiter and a dynamic reference algorithm. Experimental results are provided to assess the performance of the control algorithm for two scenarios, a resistive load and a programmable voltage source in series with a small resistor, to emulate a battery. These algorithms are particularly interesting for applications that demand control of both voltage and current within a safe operational range, such as battery systems.

The rapid growth of smart grids necessitates advanced control strategies to ensure efficient and reliable power distribution. This paper proposes a hierarchical control framework based on Model Predictive Control (MPC) for managing power distribution in a smart grid. The hierarchical structure comprises three control levels: the first hierarchy is to control the inverter variables and the LC filter voltage, the second hierarchy supervises the power control restriction for every inverter, and the hierarchy is for power coordination, which utilizes long-term condition and prediction and power supply restriction (solar or wind capability, among other conditions or restrictions). The simulation results presented in this paper validate the fast control response and the capability of coordination between the different hierarchies of the proposed strategy.

This paper presents a novel hierarchical control scheme based on Model Predictive Control (MPC) for a Voltage Source Inverter (VSI) operating under conditions of unbalanced and nonlinear loads. The increasing prevalence of renewable energy sources and the proliferation of power electronic devices has led to a growing need for robust control strategies that can effectively handle the challenges associated with unbalanced and nonlinear loads in power distribution systems. In this work, a two-hierarchy control structure is proposed, based on a full MPC strategy. The MPC controller in the first hierarchy is responsible for optimizing the VSI's switching states in real-time, taking into account the system's constraints and the desired performance criteria of the output voltage of the VSI. The MPC controller in the second hierarchy regulates the output current of the VSI to track the reference values for the load and grid power. The proposed control scheme addresses the challenges posed by unbalanced and nonlinear loads, the simulation results demonstrate the effectiveness of the proposed hierarchical control strategy in mitigating voltage deviations, minimizing harmonic distortions, and ensuring balanced operation in the presence of unbalanced and nonlinear loads. The presented approach offers a promising solution for enhancing the performance and stability of VSI-based power distribution systems, thus contributing to the overall reliability and efficiency of modern electrical grids.

Analysis and performance of a three-phase single-stage SEPIC differential-mode inverter (DMI) using a discontinuous modulation scheme (DMS) are presented in this paper. Since the DMS was previously suggested in many inverter topologies to reduce the voltage stress of utilized switching devices and enhance inverter efficiency, a simple design process to integrate DMS into the SEPIC DMI is proposed in this work. With this modulation strategy, the discontinuity of the duty cycle for one-third of the entire grid frequency cycle thoroughly minimizes the conduction losses and switching losses into the SEPIC converters. Also, it is noted that the voltage stress is significantly reduced in passive elements as well as switching devices. Furthermore, the compensation of the negative sequence harmonic components is maintained without adding extra sensors. The inverter operation along with mathematical analysis of the DMS and grid current control is presented. A PSIM simulator is used to evaluate the behavior of the proposed modulation strategy. Finally, a comparison with the conventional continuous modulation scheme (CMS) is performed for a better assessment.

Grid integration of renewable energy (REN) requires efficient and reliable power conversion stages, particularly with an increasing demand for high controllability and flexibility seen from the grid side. Underpinned by advanced control and information technologies, power electronics converters play an essential role in large-scale REN generation. However, the use of power converters has also exposed several challenges in conventional power grids, e.g., reducing the system inertia. In this article, grid integration using power electronics is presented for large-scale REN generation. Technical issues and requirements are discussed with a special focus on grid-connected wind, solar photovoltaic, and energy storage systems. In addition, the core of the energy generation and conversion—control for individual power converters (e.g., general current control) and for the system level (e.g., coordinated operation of large-scale energy systems)—is briefly discussed. Future research perspectives are then presented, which further advance large-scale REN generation technologies by incorporating more power electronics systems.

The articles in this month’s issue provide insight into the most important powerelectronics- based technologies for energy transition.

This paper proposes a Master-Slave Model Predictive Control for parallel grid-tied inverters in a microgrid. In this configuration, the Master is a grid-forming inverter with a Battery Energy Storage System as dc input, while the Slave is a grid-following PV inverter that provides the power to the load. First, the inverter models are derived and then their MPC controllers are presented in details. Finally, Hardware-in-the-Loop results are presented for different operational conditions for the microgrid, including grid connection, islanded mode and load variations. The results demonstrate the advantages of the proposed MPC such as faster dynamic response, multi variable control, adequate load sharing between the inverters, robustness to parametric uncertainties and variations and the possibility to directly include system constrains and non-linearities in the controller implementation.

Model predictive torque and flux control has shown some advantages over the classical methods. However, one of the challenges that still need to be investigated is the establishment of a control balance between the torque and flux which leads to better switching state selection. Traditionally, a weighting factor is used in the classical model predictive control (MPC). There are some new techniques that tried to avoid using a weighting factor in order to select the optimal switching state. However, in most of them, new optimization problems are added to the method. In this research, a simple discrete optimization technique is proposed for weighting factor and switching state optimization. The proposed method can be applied to the full range of operating points. The simulation and experimental results show the validity of the proposed method.

Multilevel converters emerge as a promising technology for high-power medium-voltage applications due to their different advantages. On the other hand, model predictive control (MPC) is one of the control techniques that has been widely used in different applications because of its features, such as fast transient response and flexibility to include nonlinearities. The finite control set MPC (FCS-MPC) approach for a seven-level topology converter reduces the number of calculations significantly, nevertheless depends on the circuital model making it sensitive under uncertainties. On the other hand, model-free predictive control (MF-PC) has gained attention due to its accurate prediction without previous knowledge of the power system. This paper proposes MF-PC to predict the current for each phase for the seven-level topology converter. Moreover, simulation results demonstrate superior performance and feasibility of the developed control method compared to the FCS-MPC approach applied to a seven-level topology converter.

A Multisource Inverter (MSI) comprises several DC sources in the input that can be combined together with varying voltage levels to operate at different loads to reduce the battery size of electric vehicles. Different multisource inverter configurations have been presented recently in the literature. These structures use two DC sources to operate at different demand loads by using a low battery size. The weakness of these multisource inverters is that they use a high number of power switches. In addition, these structures cannot connect two DC used sources together in series to operate under a heavy load, which increases the battery's size, increases high power losses, and reduces efficiency due to a high number of switches. This paper proposes a new topology for multisource inverters that reduces the power electronics switches and the battery size due to generating four combinations between the two used DC sources in the proposed technique. The proposed multisource topology is controlled by the model predictive due to its popular advantages. The performance of the proposal is verified through simulation results in Matlab. The results show that the MPC is a good alternative for such applications due to its simplicity, high performance, and low harmonic content.

To eliminate the common-mode voltage (CMV) for matrix converters, this paper proposes a current sensorless model predictive control with reduced calculation overhead. In contrast to other traditional CMV-reducing methods which use all permissible switching configurations, this method synthesizes the output voltage and the input current with only six rotating vectors that lead to zero CMV. The proposed technique does not need to predict future load currents and source currents for those six rotating vectors, which provides another advantage in term of computation efficiency. Additionally, all current sensors are removed by using a Luenberger state observer instead in the control loop for cost reduction. The effectiveness of the proposed method is evaluated through simulation in different operation conditions.

Model Predictive Control (MPC) is becoming more popular than ever as an alternative to conventional modulations such as Space Vector Modulation methods to control matrix converters (MCs). However, the implementation of MPC is computationally expensive, because control objectives are required to evaluate all admissible switching states of the converter. Additionally, a large number of sensors to measure the 3-phase load currents, source currents, source voltages, and input voltages of MCs increases the overall cost. To sort this out, an efficient MPC is proposed for MCs to enable fast computation and low cost. This approach eliminates the calculations of future load currents and source currents for all possible switching states, requiring only two predictions for the calculation of output voltage and input current references. Further, it removes all current sensors by employing a Luenberger observer. A simulation study has demonstrated that the proposed method can reduce the computation overhead and hardware cost dramatically, leading to high-frequency operation and good converter performance.

The transformer-based inverters in PV systems increase the weight, size, and cost of the inverter while reducing efficiency. This research presents a new PV inverter topology to increase efficiency using a reduction of dc-link. The proposed multilevel inverter is comprised of six power switches, one discrete diode, and three capacitors to produce five voltage levels. The proposed inverter is connected to a PV panel at input and a local grid at output to inject a sinusoidal current waveform into the grid. To control the grid current, a finite set model predictive control is needed to evaluate the proposed inverter. A comparison study is carried out between the proposal and other five-level inverters to verify the strengths and weaknesses of the proposed multilevel inverter. Finally, to demonstrate the performance of the proposed multilevel inverter, the simulation results are presented in the MATLAB/Simulink environment.

According to recent improvements in microgrid and Renewable Energy Sources (RESs), it is vital to use an alternative system for conventional transformers due to its lack of controllability and having high volume and weight. So, the senses gathered to the Solid-State Transformer (SST) because of its relevant advantages. A power electronic converter converts a low-frequency ac voltage waveform to a medium frequency voltage with variable amplitude in most SST structures. First, there is a need to convert the DC voltage to a pure sinusoidal one for using the High Voltage DC (HVDC) in Distributed Generator (DG) sources such as Photovoltaic (PV) farms and microgrids. Then an ac-ac converter is used to produce a medium frequency waveform. These structures need two stages of energy conversions. This paper proposes a new configuration with a specific modulation method to convert the DC voltage waveform directly to a medium frequency voltage waveform with variable maximum amplitude. The simplicity of the control system, reduced volume, and weight, as well as the reduced number of energy conversion stages are the advantages of the proposed system.

In this paper, a novel boost-based quasi resonant DC-DC converter is proposed, featuring low component count. The proposed topology also achieves a high voltage gain with a wide output power range while profiting from a simple structure. An inductor is introduced in the termination of the circuit that takes part in the resonant process instead of creating a voltage spike across the switch during the switching time. Moreover, the circuit achieves soft switching (ZVS-ZCS in turn on/off transitions of the switch), leading to reduced losses and improved efficiency. Working with a suitable switching frequency is a contributory factor in reducing the size of passive components. The operational principles and a comprehensive steady state analysis in the continuous conduction mode (CCM) as well as design considerations for the proposed converter are discussed in details.

This paper presents an improved sequential model predictive control (MPC) method for single phase photovoltaic (PV) applications. The T-type H-bridge five-level topology is selected in this paper. The proposed method achieves constant switching frequency operation of the inverter, which is advantageous over the variable switching frequency MPC methods. The proposed fixed switching frequency MPC (FSF-MPC) method eliminates the weighting factors, which represent critical element in applying classical MPC methods. Moreover, the proposed FSF-MPC method achieves low dv/dt values through using optimized switching sequences to evaluate the cost function. The simulation results of the proposed FSF-MPC method are provided and compared with variable switching frequency MPC method. The results show the fast tracking in both controllers. Whereas, fixed switching frequency and weighting factorless operation are obtained using the proposed FSF-MPC method. Additionally, lower total harmonic distortion (THD) in the output voltage is obtained using the proposed FSF-MPC method compared to classical MPC method.

Battery energy storage systems (BESSs) have be-come integral parts in photovoltaic (PV) energy systems due to their fluctuated nature. The most common solutions in the literature for hybrid PV-battery systems are based on two-stage power converter solutions with separate power converters. However, these solutions increase the cost of the system and the number of required devices. Additionally, leakage currents represent critical issue for safe and reliable operation of PV systems. This paper presents a three-port configuration for hybrid PV-battery grid-connected systems. The proposed configuration includes a common ground connection between the PV side and grid side, which results in the elimination of leakage current components. Moreover, a finite control set model predictive control (FCS-MPC) is presented in this paper for controlling the proposed three-port configuration. The proposed controller achieves the control of multiple objectives simultaneously in addition to having fast dynamic response. Simulation results of the proposed configuration and control method are provided in this paper. The results show the effectiveness of the proposed configuration for hybrid PV-battery systems.

This paper presents a new common grounded (CG) multilevel boost inverter (MI) topology for single-phase grid-tied photovoltaic (PV) applications. The proposed topology has the capability to fully eliminate the leakage currents in PV systems due to the using of the CG connection. Additionally, the proposed topology benefits the high boosting factor capability of the low PV voltage. The proposed topology represents a single stage power conversion system with reduced power components compared to the traditional two-stage PV power conversion systems. In addition, model predictive controller (MPC) is proposed in this paper to control the proposed topology. The proposed controller can control multiple objectives simultaneously without using cascaded controllers. The simulation results with the different case studies are provided. The results confirm the superiority of the proposed CG boost MI topology and the proposed MPC method. Furthermore, fast tracking of the grid active and reactive power demands is achieved using the proposed MPC method.

Grid connected voltage source converters have become inevitable means for expanding and supporting power systems. In this paper, a combined method is adapted to the converter control of grid connected micro grids against multiple risks. A single control system is proposed to cope with high power fluctuations, short circuit faults, and unbalanced operations at the same time. It is realized by using the advantages of a current control scheme in connection with a smart converter switching logic. As a result, no extra means are needed for tackling each of the undesirable conditions. The control system provides stable operation and fault-rid through capability even under unbalanced conditions. It is presented with and without virtual flux calculations. The system operation under the proposed control system is compared with the one under a conventional control system to confirm its performance superiority.

This paper proposes a model-free predictive current phasor control for three-phase grid-connected voltage source converters. The control method regulates the grid current vector magnitude and phase with respect to the grid voltage vector in a stationary reference frame. The method inherently enjoys a fast transient response and high-power quality with a low sampling frequency. It avoids any system model information in the control algorithm for current vector prediction. A direct and effective current limitation routine is embedded into the control algorithm. The method features a simple control structure and low computation burden. It lacks any pulse-width modulation sub-system, additional sensor, lookup table, state observer, and grid voltage and current transformation. The proposed method is evaluated through simulation studies, where the results illustrate the effectiveness of the method and its superiority over conventional methods under the parameter mismatch conditions.

Wireless power transmission (WPT) systems can be a safe, efficient, and economical option in the long run for motor supplying in electric vehicles. The precise design of magnetic structures has a significant impact on the performance of such systems. In dynamic WPT (DWPT) systems, especially for wireless drive applications, due to the vehicle moving in four directions, the misalignment between the primary and secondary sides is considered as a limitation of this technology. In this paper, for a DWPT system with Double D magnetic pads for both sides, adding auxiliary windings in the secondary side, and introducing a suitable compensator in the primary side, a structure is proposed that tolerates the misalignment in all four directions.

Differential-mode inverter is an attractive solution for photovoltaic (PV) microinverter applications since this structure allows to perform both voltage elevation and grid connection in a single conversion stage. In this paper a partial power differential mode inverter (PPDMI) is proposed. It is demonstrated that by using two partial power converter, the proposed solution allows to reduce the power rating of the structure by 15% in comparison to full-power structure. Moreover, averaged power processed by the converter is also reduced by 33%. In order to validate the proposed converter a PV microinverter realized with a flyback-based PPDMI has been simulated. The results show the attractiveness of the solution with estimated efficiency reaching 94.6%.

This paper presents a direct non-linear based predictive control for a single-phase Shunt Active Power Filter nine-level Packed E-Cell inverter (SAPF-PEC9). The proposed control based on a Finite Set Model Predictive Control (FS-MPC) has been designed to compensate the reactive power requested by the nonlinear load at the Point of Common Coupling (PCC). An outer loop consisting of a PI regulator together with a low pass filter is used to regulate the main capacitor voltage and to inject the proper filter reference current. Meanwhile, the overall design is very simple where a very fast and robust controller is achieved. Moreover the nine-level converter operation together with the direct predictive approach allows the reduction of the passive filter at the shunt converter terminals. Hence a microscale filter is obtained. The performance of the proposed hybrid controller in reactive power compensation, harmonics suppression and unity power factor operation is investigated under stiff grid conditions (zero impedance) through both normal and dynamic load-change operation. Simulation results are provided to validate the fast and effective dynamic performance, the very low harmonic content in the mains current as well as the DC capacitors balancing of the PEC inverter.

In this paper, a space Vector modulation scheme (SVMS) to enhance the performance of the single-stage three-phase grid-tied SEPIC-based differential inverter is presented. Compared to the traditional modulation schemes, the proposed modulation scheme offers a significant reduction in the peaks of output voltages and input currents of the utilized SEPIC modules at the same voltage gain. Moreover, the peak voltages of the utilized capacitors in SEPIC converters are reduced. Therefore, the voltage stresses, conduction losses, and switching losses have been decreased, and the system efficiency has been increased in accordance. The proposed SVMS is implemented by employing a simple modification to the traditional continuous modulation scheme (CMS) of differential inverters, which keeps the smooth operation of the grid-current control at the inverter side and verifies low execution time. Moreover, a detailed comparison between the proposed modulation scheme and traditional CMS at different power ratings is introduced. The performance of the proposed SVMS is evaluated using the PSIM environment to validate the theoretical features added to the grid-current control and the SEPIC-based differential inverter.

Model predictive control brings many advantages and it simplifies the control scheme in power electronics. However, tuning the weighting factor is one of the important open discussions on this topic. There are online and offline methods that have been introduced to select the weighting factor. The online methods are preferred because they are more feasible. In this article, an online weighting factor optimization method based on the simulated annealing algorithm is proposed. The energy of the ripple is used as a convergence criterion. The presented method can be converged in a few steps and it does not impose cumbersome computations. Therefore, the optimal voltage will be identical for a range of the weighting factor. Furthermore, the used search algorithm is parameter independent. The proposed method is implemented for an induction motor but it is also applicable for other applications. The proposed method is validated by the experimental tests.

A finite-set predictive control (FSPC) approach is designed by considering the discrete-time model of the system under control. Therefore, variations of the model parameters and disturbances due to un-modeled dynamics deteriorate the performance of the FSPC. In order to overcome this problem, this paper proposes a FSPC strategy with an equivalent input disturbance (EID) observer for permanent-magnet synchronous generators (PMSGs) in wind turbine applications. The proposed EID observer estimates the total disturbance due to variations of the model parameters and un-modeled dynamics and considers it in the design of the controller. Experimental results are given to validate the performance of the proposed FSPC scheme.

Transformerless photovoltaic (PV) inverter topologies have proven superior performance over transformer-based inverter topologies. However, they face challenges due to their high leakage currents and voltage step-up requirements. There-fore, modified topologies and/or modulation techniques are essential to limit the current leakages to standard limits. The doubly grounded (DG) inverter topologies represent efficient solutions for totally limiting the leakage currents. This paper presents a finite control set (FCS) model predictive controller (MPC) method for DG step-up five-level PV inverter topology. The proposed FCS-MPC method can control the injected grid currents and multiple capacitors voltages simultaneously with high power quality output. The modelling and design of the step-up inverter topology and the FCS-MPC method are given in the paper. Simulation results with step-up DG five-level PV inverter topology are performed to validate the proposed FCS-MPC method. Moreover, the proposed FCS-MPC method has been validated using simulation results at the various operating conditions of PV inverters.

Leakage currents represent critical issues for the operation of conventional photovoltaic (PV) inverter topologies. Recently, the common grounded (CG) PV inverter topologies have presented superior performance over the conventional PV inverter topologies from the leakage currents elimination point of view. The multilevel CG-PV inverter topologies combine both features of the multilevel output voltage and the CG connection. Among the existing CG topologies, the switched capacitor types have found wide applications due to the lower cost, volume, and losses on the passive inductors. However, burdens have been risen for the control system to achieve multi-objectives, which includes controlling the output current of the inverter and the capacitor voltages. Therefore, this paper presents a Finite Control Set Model Predictive Control (FCS-MPC) method for five-level CG single-phase PV inverter topology. The FCS-MPC method presents reduced harmonic contents of the output currents and precise tracking to its reference value. The design guidelines of the FCS-MPC method and weighting factor adjustments are provided in this paper. Simulation results are presented in order to validate the effectiveness of the FCS-MPC method.

With the development of the high-power wind turbine systems, permanent-magnet synchronous generator with direct-drive configuration is attractive for high-power wind energy conversion systems. As one of the key technologies of wind energy conversion, control technology plays an important role in the performance of wind power systems. Due to its excellent dynamic performance and multi-objective control, model predictive control has become an alternative and promising method. However, the cumbersome process of tuning weighting factors is its main drawback. In this work, a new control structure, as socalled dynamic sequential model predictive control is proposed. It avoids using weighting factors and overcomes the drawbacks of sequential model predictive control. The proposed control strategies are validated and compared with the sequential model predictive control in Plecs simulation.

The behavior of Model Predictive Control (MPC) is by principle affected by the quality of the model used for the controlled system. A parameter mismatch between the plant and the controller can affect drastically the performance of MPC. This paper presents a new strategy called model-free predictive control (MF-PC) to overcome these problems. In this approach, a recursive least squares algorithm is implemented to identify the parameters of an auto-regressive with exogenous input (ARX) model, using input and output measurements of the controlled system. The proposed method enables an accurate prediction of the controlled variables without requiring detailed knowledge about the physical system. Simulation results obtained for the current control of a two-level, three-phase voltage source inverter, demonstrate that the MF-PC is exceptionally robust against the parameter variations and the model uncertainties, compared to conventional finite-control-set MPC.

This paper proposes a horizon-one constrained model predictive control (MPC) with integral action for dc-dc H-bridge converters. An integral-action MPC law is analytically derived. The proposed controller takes into account the bilinear dynamics of the converter both in the control law derivation and constraints modeling. In addition, the proposed cost function does not presume the knowledge of the equilibrium point. In this paper, a three-level H-bridge converter for regulation purposes is considered to illustrate the proposed approach, though it is applicable to other dc-dc converter topologies as well. The paper compares the performance of the proposed analytical MPC law and the solution provided by an iterative optimisation algorithm. Simulation results are provided to verify the theoretical predictions, that is, the control law rejects constant disturbances while satisfying the designed constraints.

This paper presents a novel model predictive control (MPC) method for the single-inductor multi-output (SIMO) converter. The novel MPC method combines the conventional MPC strategy and the event-triggered control strategy, i.e. event-triggered MPC (ET-MPC). On one hand, the proposed ET-MPC method inherits the feature of fast dynamic response of MPC to reduce the cross regulation of SIMO converter; On the other hand, the MPC scheme is activated when the state of the SIMO converter triggers a preset triggering condition. Therefore, the unnecessary online computation and switching actions can be avoided, since the MPC scheme is suspended if the triggering condition is inactive. Consequently, the ET-MPC method has two advantages over the conventional MPC method: i) lower computational burden, ii) and less switching actions which contribute to lower switching losses. Moreover, the weighting factor for tuning the switching frequency can be deleted because the unnecessary switching action are all removed. The steady-state operation and dynamic performance cases are studied. The results demonstrate that PS-CRS is able to regulate the SI-MIMO DC-DC converter effectively and robustly.

This paper presents an adaptive stator current disturbance observer based on the model predictive current control (PCC) algorithm. For the various disturbances, the disturbance observer (DO) algorithm estimates the lumped disturbance and makes a feedforward compensation to correct the output. However, the discrete characteristic of current prediction error is neglected in conventional stator current disturbance observer (SCDO). Based on the detailed analysis of the stator current prediction error, the proposed method structures a parallel strategy to observe the discrete disturbance related to each voltage vector separately, and designs an adaptive compensation strategy to eliminate the prediction error. The effectiveness of proposed method is verified using experimental tests in the permanent-magnet synchronous motor (PMSM) system.

An indirect model predictive control (iMPC) approach is proposed for regulating a grid current waveform provided by a single-phase inverter connected to a distorted grid. An algorithm implemented in the control system takes into account a significant computational delay. The distorted grid with the 5th harmonic is considered, which imposes additional restrictions on the iMPC and phase-locked loop utilization. Hardware setup involves a three-level neutral point clamped inverter and an inductive output filter. From a finite set of modulation index values, the iMPC current control selects one value for an external fixed switching frequency driver based on the LS-PWM strategy. Relevant cost function composition and modulation index regulation for improvements of transient and steady-state responses are discussed. Simulation and experimental verification is presented.

This paper proposes a new topology with reduced switch count for a regenerative flying capacitor multilevel inverter. This paper also introduces a new control strategy, the use of Predictive Control. The resulting control scheme is extremely simple to understand and to implement. In addition, simulation results present a very good performance of the converter.

A new multilevel converter topology is proposed in this paper. Low component count and compact design are the main features of the proposed topology. Furthermore, the proposed converter is a capacitor-, inductor-, and diode-free configuration, allowing reducing the converter footprint, increasing the lifetime and simplifying the control strategy. Further, a comparative study is carried out to highlight the merits of the proposed circuit as compared to existing multilevel topologies. Finally, simulation results for the three-level version using different modulation strategies are presented.

This paper proposes a Modulated Model Predictive Control (M2PC) algorithm for the three-phase Packed-U-Cells, PUC5, converter, that aims to minimize the output current error and balance the voltages of the DC bus capacitors. In order to do so, two cost functions are defined. The first one selects the sector in the SV diagram that minimizes the output current error, not taking into account the redundancies of the converter voltage vectors. After this, a second cost function for balancing the DC bus capacitor voltages is evaluated, considering only the voltage vectors of the chosen sector, including their redundancies. In this way, the proposed M2PC results in output voltages with fixed switching frequency, having a positive impact on the design of the output filter. Simulation results are shown, comparing the proposed M2PC and the standard variable frequency MPC strategies in terms of output current and voltage, internal capacitor voltage balancing and harmonic content.

Servo drives require high dynamics and reliability on speed control. Conventional cascade linear controllers suffer from the proportional-integral parameters tuning work and low dynamic response, due to their cascaded structure. In this paper, an improved model predictive direct speed control is proposed with rapid speed tracking and very small speed offset. The new control scheme eliminates the cascaded structure by predicting the future speed in discrete steps. The optimal voltage vector to control the motor is then selected according to an evaluation criterion for speed and flux tracking. To reduce the system cost and improve the reliability, a load torque observer is adopted to estimate the actual load torque. Besides, to avoid torque oscillations and overshoots during rapid speed variation, a torque suppression factor is incorporated into the cost function. Furthermore, a myopic prediction correction method is developed to enhance both the dynamic and steady-state responses. Simulation and hardware-in-the-loop results are presented to validate the effectiveness of the proposed method.

The model predictive control is increasingly used as a high performance control strategy in converters and drives. This paper presents a new sensorless predictive power control method for the active front end rectifiers. Sensorless application of predictive control method faces more challenge compared to conventional control methods because the accurate prediction is dependent on the accurate voltage estimation. The model based estimation method is used in the predictive control technique in this research. This technique creates two problems, i.e., the derivatives of the currents, and the need for accurate values of the parameters of the model. The first problem is diminished by using the proposed filters. On the other hand, the inductance is estimated based on the model reference adaptive system observers to improve the accuracy of the line voltages estimation, although the proposed sensorless control is stable even without the inductance estimation. For a robust parameter estimation, a new adaptive function is achieved via Lyapunov technique. Simulation and experimental results verify the performances of the proposed methods.

This paper proposes an innovative active voltage control technique for flying-capacitor (FC) multilevel converters. The proposed active control method on the basis of the logic-equations exploits converter's measured variables including the capacitor voltages and output current to generate a switching state that regulates the FC voltages at reference values and also produces the commanded PWM voltage-level. Simulation results and experimental measurements are provided to confirm the introduced method and derived equations.

A modular-concatenated-cell (MCC) multilevel voltage-source converter topology is investigated in this paper, and its basic configurations are reviewed. A set of logic-equations are derived for control of the 1-cell 3-level and 4-cell 6-level MCC inverter topologies. Simulation results are provided to confirm the four-cell 6-level configuration and the proposed logic-equations. Furthermore, a 3-level MCC converter topology and its logic-equations-based modulation technique are experimentally verified using a 2 kW laboratory prototype.

The direct matrix converter (MC) is a promising converter that performs direct AC-to-AC conversion. Model predictive control (MPC) is a simple and powerful control strategy for power electronic converters including the MC. However, weighting factor design and heavy computational burden impose significant challenges for this control strategy. This paper investigates the sequential MPC (SMPC) for a three-phase direct MC. In this control strategy, each control objective has an individual cost function and these cost functions are evaluated sequentially based on priority. The complex weighting factor design process is not required and the computational burden can be reduced. In addition, specifying the priority for control objectives can be achieved. A comparative simulation study with standard MPC is carried out in Matlab/Simulink. Control performance is compared to the standard MPC and found to be comparable. Simulation results verify the effectiveness of the proposed strategy.

Finite Control Set Model Predictive Control (FCS-MPC) allows to deal with non-linearities of the system and obtain a fast dynamic response. Therefore FCS-MPC is a good alternative to govern complex power converters or when fast transient operation is required. A problem about the implementation of FCS-MPC is the computational cost, which is bigger for multilevel converters. This paper proposed a new method to implement FCS-MPC reducing the necessary iterations in a 3-phase 4-level Flying Capacitor converter. Simulation results show that the proposed FCS-MPC strategy produces an effective control of the load current, while keeping balanced capacitor voltages with lower necessary iterations.

Predictive control has recently emerged as a promising alternative to more traditional methods for the control and modulation of power converters. This paper presents an overview of predictive control techniques applied to matrix converters. The paper highlights that predictive control strategy is a promising alternative to conventional modulator based linear control for matrix converters due to its simplicity and flexibility to include additional constraints within the control to have it suitable for different applications. In addition to describing many advantages of predictive control techniques, its limitations and weaknesses are also discussed along with some future trends and applications. Most important control aspects of predictive control are demonstrated through simulation analysis.

High voltage direct current (HVDC) transmission systems play an increasingly important role in offshore wind energy and long distance energy transmission systems. Modular multilevel converter (MMC) is an attractive topology for HVDC systems, due to its good modularity, scalability and inherent fault tolerant capabilities. For such topology, model predictive control (MPC) is a promising alternative. In particular, the long-horizon MPC provides better performances in terms of smaller THDs at very low switching frequency. However, its computational load is seen as a big challenge. In this paper we apply a long-horizon model predictive current control (MPCC) to a seven-level MMC-HVDC system. A switch and extrapolation and capacitor voltage sorting techniques are developed and combined to reduce the total computational burden. Performances of the proposed control strategy are evaluated with simulation results at a 65 MVA back-to-back 7L-MMC-HVDC configuration.

Finite-control-set-based predictive torque control (PTC) method has received more and more attention in recent years due to its fast torque response. However, it also has two drawbacks that could be improved. First, the torque reference in the cost function of the existing PTC method is generated by the proportional-integral speed controller, so torque reference's generation rate is not fast and its accuracy is low especially when the load torque is given suddenly and inertia value is varying. In addition, the variable prediction of the traditional PTC method depends on the system model, which also has the problem of parameter uncertainties. This paper investigates a disturbance observer (DOB)-based PTC approach for induction motor systems subject to load torque disturbances, parameter uncertainties, and time delays. Not only does the speed loop adopt a DOB-based feed-forward compensation method for improving the system disturbance rejection ability and robustness, but the flux, current, and torque predictions are also improved by using this technique. The simulation and experimental results verified the effectiveness of the proposed method.

Finite control set model predictive control techniques have been emerged as good alternatives in particularly for multilevel and multiphase power converters, for which switching vectors with multiple magnitudes/directions are available but the modulator or switching table design becomes complex. In this paper, a finite-control-set model predictive direct torque and power control (FCS-DTC-DPC) for grid-tied three-level neutral-point clamped back-to-back power converters in permanent-magnet synchronous generator wind turbine systems is presented and experimentally compared with its counterpart: switching table-based direct torque and power control (ST-DTC-DPC). Both methods have been implemented and verified at a lab-constructed setup with a fully FPGA-based real-time controller. Experimental results confirm that both achieve (equivalently) good control dynamics, whereas FCS-DTC-DPC outperforms ST-DTC-DPC in terms of steady-state control performances at similar switching frequencies but has a higher computational demanding and is more sensitive to system parameter variations.

This paper presents a model predictive control (MPC) of five-level H-bridge neutral-point-clamped (NPC) quasi-impedance source inverter (qZSI). The proposed control technique is designed to handle three control objectives with simple and effective approach. The output current, the input current and the capacitor voltage are the control objectives of the proposed MPC algorithm. To fulfill these control objectives, multi-objective based cost function is employed. Furthermore, qZSI has been combined with the 5-Level H-bridge NPC inverter so as to obtain power converter topology with buck/boost and dc/ac conversion functionality in a single stage for high power PV applications. Simulation results verify the proposed multi-objective MPC algorithm and inverter topology.

This paper proposes a model predictive speed control of a permanent magnet synchronous machine (PMSM). The control scheme has a cascade architecture, where the inner loop uses a finite set model predictive control scheme (FS-MPC) for the electrical subsystem, and the outer loop uses a dead-beat model predictive control for the mechanical subsystem. Due to the discrete nature of the control platform an accurate discrete model of the systems is necessary. In this work both systems, electrical and mechanical, are discretizated with a second order Taylor method. Simulation results are presented to validate the proposed control strategy.

Multilevel converters have many advantages in power electronics. In particular, the Flying Capacitor (FC) converter is an attractive choice as it can generate high quality output waveforms and reach high power levels. Several works have been presented in the literature for voltage capacitor balancing, relying on self-balancing property. Nevertheless, the conditions for self-balancing operation cannot be guaranteed in several practical applications. In this paper, a simple closed-loop scheme, based on Model Predictive Control (MPC), is used to properly modulate the converter output voltage in order to keep the capacitor voltages at the desired values. As the proposed modulation strategy regulates the capacitor voltages, wide bandwidth linear controllers can be used for the current tracking, improving the dynamic and steady-state behavior of the overall system.

Multilevel converters are an attractive alternative for medium voltage applications. The Stacked Multicell Converter (SMC), in particular, is a multilevel converter that allows to increase the output voltage level compared with the classical Flying Capacitor Converter, while decreasing the stored energy in the converter. This paper presents the application of Finite Control Set Model Predictive Control (FCS-MPC) in a three phase SMC with two cells and two stacks. The strategy controls simultaneously the load currents and capacitor voltages. simulation results show that the FCS-MPC strategy produces an effective control of the load current, while keeping balanced capacitor voltages. In addition, it is demonstrated that FCS-MPC outperforms Phase Shifted Pulse Width Modulation with linear controllers in transient and steady state operation.

Multilevel converters are an attractive alternative for medium voltage applications. The Stacked Multicell Converter (SMC), in particular, is a multilevel converter that allows to increase the output voltage level compared with the classical Flying Capacitor Converter, while decreasing the stored energy in the converter. This paper presents the application of Model Predictive Control (MPC) in a three phase SMC with three cells and two stacks (3×2). The strategy controls simultaneously the load currents and capacitor voltages. A problem about the implementation of MPC is the computational cost, which is bigger for multilevel converters. In the case of SMC 3×2 it is necessary to do 19683 iterations, for This paper proposed a new method to implement MPC reducing the necessary iterations from 19683 to 343. Simulation results show that the proposed MPC strategy produces an effective control of the load current, while keeping balanced capacitor voltages and lower THD that classical MPC with 57.38 times lower iterations.

Fault tolerant ability is one of the most important tasks in high power converters. In this paper, a comparison between conventional fault tolerant methods is done for four applicable methods. For this purpose, their performance is investigated in specific case study and simulation results are used to illustrate their advantages and disadvantages. The most important features taken into account are maximum available voltage, harmonic distortion of output voltage and input current, and magnitude of common mode voltage. Finally, a decision algorithm based on the results is suggested to select suitable method to control inverter under specific faulty condition.

Model-based predictive direct control methods are advanced control strategies in the field of power electronics. To control an induction machine (IM), the predictive torque control (PTC) method evaluates the electromagnetic torque and stator flux in the cost function. The switching vector selected for the use in the insulated gate bipolar transistors (IGBTs) minimizes the error between references and the predicted values. The system constraints can be easily included. The predictive current control (PCC) strategy assesses the stator current in the cost function. The weighting factor is not necessary. Both the PTC and PCC methods are very useful direct control methods that do not require the use of a modulator. In this paper, the PTC and PCC methods are carried out experimentally for an IM on the same test bench. The behaviors and the robustness in steady state and the performances in transient state are evaluated.

This work proposes a new control scheme for electrical drives system, named cascaded predictive speed control (PSC). The strategy seeks to maintain the simplicity of the classic predictive control while excluding linear or other controllers. The control strategy has a cascade architecture, similar to the techniques of classical control (FOC or DTC). The outer loop controls the speed of the machine, determining a reference torque through a mechanical dynamic model, which allows tracking the speed reference. The inner loop controls the stator current with a cost function that selects the state of the converter which generates the best tracking references for the stator current synchronous components. Preliminary simulation results confirm the effectiveness of this approach, which produces produces a high quality drive control.

An encoderless predictive torque control (PTC) is proposed in this paper. By using a rotor flux model reference adaptive system (MRAS) estimation method to PTC, the system has the virtue of low cost due to the absence of PWM and speed measurement components. PTC requires not only estimated speed but also estimated stator and rotor flux. In implementation, a compensated MRAS is considered for obtaining good flux estimations. The experimental results confirm that this control strategy has very fast dynamics, can adapt a very wide speed range, and shows good performance both at transient and steady states.

In this paper, a predictive torque control (PTC) algorithm is introduced for controlling an induction motor (IM) fed by a bidirectional quasi Z-source inverter (BQZSI). A torque, stator flux and capacitor voltage magnitudes control algorithm evaluates a cost function, based on a simple discrete models of the IM and the BQZSI, for each BQZSI available switching state. The voltage vector with the lowest torque, a stator flux and capacitor voltage magnitude errors is selected to be applied in the next sampling interval. The proposed PTC algorithm, with its single structure, can control both sides of the BQZSI to optimize the motor performance with an extremely simple and versatile control algorithm and without any dynamic response limitation caused by the cascaded control structure. A high degree of flexibility is obtained with the proposed control technique due its online optimization algorithm. This paper proposed a new adjustable speed drive system based on a three-phase BQZSI feeding an induction motor. Where, the interesting advantages of the PTC algorithm are combined by the advantages of one of the most interesting power electronics converters, the BQZSI. Simulation results for a 4 kW IM are presented to validate the new proposed electrical drive system.

This paper proposes a Machine Drive based on a Modular Multilevel Converter. The proposed converter uses current source cells with asymmetrical IGCTs as switching devices. A control scheme to manage the input and output current and, additionally, reduce the oscillations in the inductors currents is also proposed. The resulting machine drive will exhibit high power and high dynamical performance as shown in the simulation results.

Model predictive control has emerged as a very powerful method for controlling of electrical energy. One of the major advantages for this control is the performance of the power converters become more better comparing with the traditional modulation control techniques. In this paper, a model predictive control is used to drive a three phase grid connected Quasi-Z-Source Inverter (qZSI) to improve the performance of the three phase injected output current. This technique uses a model of the qZSI and capacitor voltage, input inductor current and AC three phase output load currents to predict the behavior of the measured parameters. The resulting closed-loop system achieves high dynamic performance for all controlled parameters. The total system has been analyzed, simulated by using MATLAB/SIMULINK program then implement by using dSPACE 1103 to prove the idea.

Modular multilevel converter features high power quality and has high availability due to its inherent modularity. Those characteristics make this converter well suited for high voltage DC transmission applications. In this paper, a new application of modular multilevel converter in solar photovoltaic plants is proposed. The proposed structure can use higher voltages than standard photovoltaic plants, hence reducing internal losses. Additionally, an storage element can be integrated with the converter in order to perform peak shaving. The proposed topology and control strategy are shown and simulation results confirm their performance.

In this paper is presented an alternative to generate sinusoidal output voltage waveforms using predictive control in an indirect matrix converter while achieving sinusoidal source currents on the input side. These objectives are accomplished by using a predictive control scheme which calculates the future values of the variables to be controlled in order to choose the converter state that produces the minimal error between them and their references. The proposed predictive method is tested by simulation results, obtaining sinusoidal output voltage and achieving a desired input displacement factor, with a low THD on both source currents and load voltages.

Direct matrix converter (DMC) is an AC-to-AC direct power conversion topology based on controlled bi-directional switches that can generate variable output voltages and sinusoidal source currents with variable power factor. Cascaded Matrix Converter (CMC) is a multilevel converter which combines the main characteristics of multi-cell power topologies and direct power conversion. The basic module is based on 3×2 direct matrix converter cell. This converter is fully regenerative, with multilevel output voltage and sinusoidal source current. In this work a reactive power control using a phase-shifted PWM scheme is presented. The modulation scheme can be developed using a simple digital logic and the results from open and closed loop tests are presented to evaluate the performance of proposed modulation.

A new predictive control strategy for current source rectifiers which allows an effective control of source and load currents is presented in this paper. This method uses the commutation states of the converter in the subsequent sampling time according to an optimization algorithm given by a cost function and the discrete system model. The two control goals are: (a) regulation of dc-link current according to an arbitrary reference, and (b) a good tracking of the source current to its sinusoidal reference. The feasibility of the proposed method is verified by MATLAB/Simulink software.

This paper addresses to some of the latest contributions on the application of Finite Control Set Model Predictive Control (FCS-MPC) in Power Electronics. In FCS-MPC , the switching states are directly applied to the power converter, without the need of an additional modulation stage. The paper shows how the use of FCS-MPC provides a simple and efficient computational realization for different control objectives in Power Electronics. Some applications of this technology in drives, active filters, power conditioning, distributed generation and renewable energy are covered. Finally, attention is paid to the discussion of new trends in this technology and to the identification of open questions and future research topics.

This Special Section is aimed to research academics and practicing engineers of the industrial electronics and industrial informatics communities to present their most recent findings related to digital control systems in power electronics. It is our pleasure to present this third part of the Special Section on Digital Control Systems in Power Electronics and Drives. The first part was already published in the IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS in August 2012. The second part was published in the IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS in February 2013. Now, we present the third and final part of this Special Section where more than 60 papers will be published. This Special Section presents to the power electronics community the most recent advances with topics such as the following: Modern digital control strategies and algorithms; Modulation methods; Advances in hardware implementation: FPGA, DSP, microcontrollers, etc.; Application to all type of topologies in power electronics; Application to all type of AC drives; and Other applications like renewable energies and smart grids, transportation, mining, pulp and paper, etc.

A predictive control algorithm specially developed for shunt active power filters aimed to compensate reactive power and current harmonics components is presented and analyzed. The proposed predictive control algorithm is implemented in a three-phase four-leg voltage-source inverter (4L-VSI). The use of a 4L-VSI allows the compensation of current harmonics, reactive power and neutral current harmonics generated by single-phase non-linear loads. A detailed mathematical model of the filter, including the effect of the power system equivalent impedance is derived and used to design the proposed predictive control algorithm. The proposed active power filter and associated control scheme performance and compensation effectiveness are demonstrated by simulation and with experimental results.

In this paper two control techniques: Finite States - Model Based Predictive Control (FS - MBPC) and Fuzzy Logic Control (FLC) are developed to obtain arbitrary output currents, needed in a variable speed Wind Energy Conversion System (WECS). In this study, the simulation performance between FS-MBPC and FLC of the rotor current in a Doubly Fed Induction Generator (DFIG) with an Indirect Matrix Converter is evaluated. The simulations were carried out with constant shaft speed, and constant ramp speed with arbitrary rotor current references. Both FS-MBPC and FLC showed very high performance, following smoothly and rapidly the current reference with a very low error. The FS-MBPC dynamic response is slightly better than of the FLC. However, fewer mathematical calculations, and less measured data, and fewer computational requirements suggest that FLC can be easier to implement in FPGAs instead of composite microprocessor-based control platforms.

Large-scale photovoltaic energy conversion systems (LS-PECS) are currently well into the megawatt range. Therefore multilevel converters have been proposed as an attractive solution due to medium voltage operation, higher efficiency, power quality, and possibility to connect PV strings separately to each dc-link. However, the latter advantage makes the inverter susceptible to severe voltage unbalances due to the inherent power unbalance produced by the individual maximum power point tracking (MPPT) of the PV strings. This is particularly the case of the cascaded H-bridge inverter (CHB) where power cell and phase unbalances occur. In this work a new single dc-bus collector bus bar CHB is proposed for a multistring LS-PECS configuration. The operation with a single dc-bus is enabled by adding an isolation dc-dc converter stage to each power cell of the CHB. This allows inherent balanced operation of the CHB while fully decoupling the multistring PV-system from the grid tie inverter. This also greatly extends the operating range of the system compared to previous solutions. Simulation results for a 3.3kV 7-level CHB tested under dynamic conditions are presented and serve as a preliminary validation of the configuration and control schemes.

Modular multilevel cascaded converter offers several advantages for high voltage DC transmission systems such as high modularity and power quality. However, they also present an interesting challenge from the control point of view, due to its coupled current dynamics and the voltage balance of floating capacitors. This work presents a voltage balance scheme which does not affect the input nor the output voltages and currents, and its dynamics is independent on the power operating point. Simulations results show a good dynamic of the voltage balance under changes in the DC voltage reference and reversion on the power flow.

Current model predictive control for a grid-connected four-leg voltage source converter application is presented in this paper. The solution of the optimum criterion defined by predictive control is considered as the reference current. This current will be applied based on projections of the different current control vectors corresponding to the switches states. Geometrical properties of the predicted current projections are used to achieve a current control strategy operating at fixed switching frequency. A laboratory model of the four-leg converter and its load has been constructed and its performance has been tested through experiments.

This paper proposes a modification in the maximum power point tracking (MPPT) by using model predictive control (MPC). The modification scheme of the MPPT control is based on the perturb and observe algorithm (P&O). This modified control is implemented on the dc-dc multilevel boost converter (MLBC) to increase the response of the controller to extract the maximum power from the photovoltaic (PV) module and to boost a small dc voltage of it. The total system consisting of a PV model, a MLBC and the modified MPPT has been analyzed and then simulated with changing the solar radiation and the temperature. The proposed control scheme is implemented under program MATLAB/SIMULINK and the obtained results are validated with real time simulation using dSPACE 1103 ControlDesk. The real time simulation results have been provided for principle validation.

Modular multilevel cascaded converter emerges as an important alternative in high voltage DC transmission systems, due to its high reliability and power quality. This converter is composed by several identical cells whose are, in turn, composed by a chopper or an H-bridge and a floating DC capacitor. This paper proposes a modular multilevel converter with a novel cell topology based on a current source H-bridge. The use of this cell could improve the input and output power quality and, due to the IGCT current and voltage ratings, reduce the number of cells in series to achieve the required DC voltage and at the same time increase the transmitted power. Analysis and simulation of the proposed topology and its control are given.

This paper presents a novel model predictive control method for current source converters (CSC) following the duality with voltage source converters (VSC). In VSC the predictive control is applied to the output current, while in this work the CSC is controlled through the output voltage. The method is based on the discrete prediction model of the system, including the converter and output filter. The model is used to predict future behavior of the system variables for each switching state of the converter. The predictions are evaluated in a cost function that weights the level of accomplishment of the control goals. The switching state with best performance is then generated. The proposed algorithm predicts the output terminal voltages (includes the output filter capacitors), ensuring sinusoidal voltage generation without the need of cascaded control loops, coordinate transformations and modulation schemes found in classic solutions. In addition, low switching frequency is imposed by including the switching frequency in the cost function. Simulation results show a preliminary validation of the proposed control scheme, with comparable performance to the classical solutions, especially in terms of the current and voltage harmonic distortion.

Presented in this paper is a new strategy for indirect matrix converters that effectively mitigates common-mode voltages and allows an optimal control of source and load currents. This method uses the commutation state of the converter in the subsequent sampling time according to an optimization algorithm given by a simple cost function and the discrete system model. The control goals are regulation of output current according to an arbitrary reference and also a good tracking of the source current to its reference, which is imposed in order to obtain a sinusoidal waveform with low distortion. The technique is enhanced by a reduction of the common-mode voltage with an extra term in the cost function so as to avoid early motor winding failure and bearing deterioration. Simulation results support the theoretical development.

This paper presents a current control scheme with instantaneous reactive power minimization for an indirect matrix converter. The strategy uses the commutation state of the converter in the subsequent sampling time according to an optimization algorithm given by a simple cost function and the discrete system model. Using this strategy, harmonics in the input current generated by the resonance of the input filter are strongly reduced. Simulation and experimental results with a laboratory prototype are provided in order to validate the control scheme, and the effects of a distorted source voltage and filter resonance are analyzed.

The 17 papers in this special section are aimed to research academics and practicing engineers of the industrial electronics and industrial informatics communities to present their most recent findings related to digital control systems in power electronics.

Multilevel converters are considered today as the state-of-the-art power-conversion systems for high-power and power-quality demanding applications. This paper presents a tutorial on this technology, covering the operating principle and the different power circuit topologies, modulation methods, technical issues and industry applications. Special attention is given to established technology already found in industry with more in-depth and self-contained information, while recent advances and state-of-the-art contributions are addressed with useful references. This paper serves as an introduction to the subject for the not-familiarized reader, as well as an update or reference for academics and practicing engineers working in the field of industrial and power electronics.

This paper presents an overview of the state of the art in reactive power compensation technologies. The principles of operation, design characteristics and application examples of Var compensators implemented with thyristors and self-commutated converters are presented. Static Var generators are used to improve voltage regulation, stability, and power factor in ac transmission and distribution systems. Examples obtained from relevant applications describing the use of reactive power compensators implemented with new static Var technologies are also described.