This work introduces a six-level flying capacitor-based converter (6L-FCB) tailored for three-phase systems operating from a single DC source. The proposed structure overcomes key drawbacks of traditional multilevel designs, including dependence on multiple isolated sources, auxiliary voltage-balancing hardware, and excessive device counts. Each phase incorporates four flying capacitors, with voltage balance maintained through an optimized switching-state selection scheme that operates without additional circuitry. The control employs a level-shifted carrier PWM method combined with a priority index mechanism that exploits phase current polarity to regulate capacitor voltages. This strategy enables straightforward implementation while delivering high-quality output voltages with low harmonic distortion. Comparative analysis against existing six-level alternatives highlights the performance and hardware advantages of the proposed design. Simulation studies confirm the robustness of the modulation and balancing methods across various load and modulation index conditions.

This paper presents a three-phase seven-level nested switched-capacitor (7L-NSC) inverter that incorporates two symmetrical flying capacitors per phase, each rated at one-third of the DC-link voltage. To ensure reliable operation across all conditions, a finite control set model predictive control (FCS-MPC) strategy is employed. This control approach leverages redundant switching states to maintain accurate current tracking and ensure effective voltage balancing of the flying capacitors. A detailed mathematical analysis of the inverter, including capacitor voltage ripple behavior under both steady-state and transient conditions, confirms the robustness of the proposed control method. The performance of the control strategy is validated through comprehensive simulation studies in PSIM and verified by experimental testing using a laboratory-built prototype. Results from both simulations and hardware experiments demonstrate the method’s capability to maintain low THD and stable capacitor voltages, confirming its suitability for advanced multilevel inverter applications.

The global push for net zero emissions (NZE) by 2050 has accelerated the adoption of electric vehicles (EVs), supported by rapid advances in lithium ion battery (LiB) technologies, supportive policies and market incentives. Despite progress in addressing challenges such as high costs and range anxiety, the limited lifetime of LiBs remains a critical barrier to widespread EV adoption. This paper explores time-varying current (TVC) charging strategies, particularly pulse current charging (PCC), as promising alternatives or complements to the conventional constant current-constant voltage (CC-CV) method. It reviews recent trends in EV adoption, LiB chemistries, and state-of-health (SoH) estimation methods, including experimental, adaptive, and data-driven approaches. The analysis highlights the potential of PCC strategies to extend battery lifetime, enabling opportunities in vehicle-to-grid (V2G) services and shared mobility systems. By addressing current challenges and leveraging these opportunities, TVC charging methods offer promising solutions to extend the useful life of LiB and support a sustainable and decarbonized transportation ecosystem.

textit-The ability of Dual Active Bridge (DAB) converters to provide isolated, bidirectional power conversion offers distinct advantages over traditional converters, making them ideal for Vehicle-to-Grid (V2G) applications. Effective power regulation in such applications requires advanced modulation techniques. This paper proposes an innovative dual-phase shift strategy for DAB converters to enhance active power transfer and efficiency. Through analytical modeling and simulations, this approach demonstrates improved performance in managing bidirectional power flow. The results confirm its alignment with prior research, underscoring its potential for scalable and efficient energy systems. Specifically, the proposed Analytical Dual-Phase-Shift (ADPS) method derives closed-form expressions for optimal phase shift angles, minimizing reactive power and ensuring Zero-Voltage Switching (ZVS) across all bridge legs under light-load conditions. Compared to conventional single-phase and dual-phase shift methods, ADPS achieves a reduction of up to 12% in reactive power and an improved power factor without increasing control complexity. Simulation results validate the effectiveness of the approach, making it a promising solution for high-efficiency DAB control in modern DC-DC power conversion applications.

The four-level single flying capacitor converter (4L-SFC) is an efficient topology for medium-voltage applications, offering a reduced component count over traditional four-level flying capacitor converters. However, maintaining balanced capacitor voltages is a key challenge in this topology, which is critical for stable and reliable operation. In this paper, an active voltage balancing method for 4L-SFC converters is presented, using a straightforward algorithm to adjust voltage levels in response to real-time measurements of capacitor voltages and phase currents. As a result of the proposed method, capacitor voltages remain balanced across a wide range of modulation indexes and operating conditions without significantly increasing switching frequency. Simulation results have demonstrated the effectiveness of the proposed approach, demonstrating that it is capable of maintaining stable capacitor voltages.

Renewable energy sources (RES) such as solar photovoltaic (PV) are employed in electric vehicle (EV) charging stations to promote sustainable transportation and reduce the load on the AC grid. This paper introduces a modular power converter topology that interfaces with solar PV, EV batteries, and the AC grid. The proposed topology supports EV battery charging in two modes: DC/DC (from PV modules) and AC/DC (from the AC grid). Additionally, during peak hours, EV batteries can function as energy storage units (ESUs) in vehicle-to-grid (V2G) mode. A central element of the proposed topology is the submodule (SM), which is implemented as a single-stage isolated bidirectional Cuk-based converter. This converter is chosen for its exceptional features, including high efficiency and inherent power factor correction (PFC) due to continuous input and output currents. The paper first details the operating modes of the Cuk-based SM. To improve performance, an extra switching state is added in the AC/DC (rectifier) mode, enabling the second-order harmonic from the AC grid to be stored within the Cuk SM instead of being passed to the battery. Additionally, power losses at the SM level are examined, and the effectiveness of the proposed topology is demonstrated through experimental results.

One of the main challenges of the NPC topology in high-power applications is to balance the power losses of the switching devices. This paper proposes a modulation method for loss balancing among main switching devices of the NPC converter. The concept of the proposed modulation scheme is based on reconstructing the middle voltage level of each phase by a linear combination of other voltage levels. By applying the proposed modulation scheme, the power losses of switching devices are balanced. However, an added feature of the reconstructed voltage levels is that its implementation results in lower neutral point current over one sampling period. The proposed scheme retains the merits of NPC topology such as the dv/dt of output voltage and dynamic voltage sharing of the switches. In addition, due to reduced rms current of the dc capacitors in the proposed scheme, the use of bulky and large capacitors is avoided. Simulations and experiments are presented to demonstrate the effectiveness of the proposed modulation method.

This paper investigates the control of the Modular Multilevel Converter (MMC), a versatile converter topology. The MMC offers advantages such as modularity, scalability, and fault- tolerance capabilities. To address the challenges of controlling the MMC, various methods including Model Predictive Control (MPC) have been proposed. This paper focuses on online weighting factor selection for MPC in Direct MPC and Indirect MPC and emulating these control techniques with neural network controllers. Dynamic equations of the MMC considering a novel method for including the discrete-time common model voltage are derived, and direct MPC (DMPC) and indirect MPC (IMPC) with online weighting factor selection are implemented. Auto-tuned DMPC and IMPC are used to extract data for training neural networks, which emulate the auto-tuned MPC controllers.The optimal neural network structure is selected and trained. Comparisons of steady-state and transient performance among auto-tuned DMPC, IMPC, and neural network-based controllers reveal that neural network-based controllers perform similarly to conventional auto-tuned MPC controllers, but with reduced computational burden. These controllers exhibit improved robustness to parameter mismatches and unpredictable converter performance, indicating their potential as viable replacements for conventional auto-tuned MPC controllers in MMC control, offering enhanced efficiency and reduced calculation burden.

PWM voltage source converters (VSCs) are increasingly used for connecting to the power grid for small Distribute Power Generation System (DPGS). A high-order low-pass LCL filter is adopted to get rid of the PWM carrier and sideband harmonics. However, LCL filter bring undesired resonance effect which generate stability problems for grid current control. Passive and Active damping are used to eliminate the resanonce peak. Passive damping reduces the filter effectiveness and also brings power loss issue. This paper presents a new systemmatic design approach for a single phase grid-connected Distributed Power Generation System (DPGS) inverter current control loop that actively damps the LCL filter resonance frequency while keeping inverter control variable well regulated. Two current control structures: PI control in synchronous reference frame (SRF) and PR control in stationary frame are adopted in cascade with a notch filter in current control loop. Details of the proposed active damping along with current controller design, mathematical modeling the LCL filter, simulations and experiment results are presented and discussed.

In this paper, a new single-stage isolated bi-directional AC-DC converter with the appropriate controller for Electric Vehicle application is proposed. The topology uses only 6 active switches. Single-stage power conversion reduces the cost and volume. Instead of using an Electrolytic capacitor with limited life-time, it uses a film capacitor. This increases the reliability of the system. The low frequency power ripple produced by the single-phase AC-DC power conversion is not allowed to the battery. This increases the life-time of the battery compared to conventional chargers. A three part controller to shape the input current, control the power, and prevent the low frequency power ripple from going to the battery is proposed. Simulation results, as well as experimental results to verify the theory, are presented.

In many applications such as power converters for fuel cells or distributed generating (DG) systems there is a need to increase the DC voltage before being inverted to AC grid or load with a higher voltage. The standard approach is to use a DC-DC converter to boost the input voltage followed by a buck inverter to converter the increased DC voltage into AC. Having two stages of conversion results in higher losses, volume, cost and component count. In this paper a single-stage inverter is proposed with desirable properties of step-up/down conversion as well as zero voltage switching (ZVS). Due to only one stage of conversion fewer components are used compared to the double-stage converters, and the cost and volume is lower. ZVS allows using higher switching frequency and smaller passive components and faster dynamic response. The predictions of circuit analysis and the suggested optimal control scheme are verified by simulation as well as by experimental results.

In this paper, an isolated bidirectional series resonant converter is proposed for transportation applications such as mid-size electrified airplanes. The proposed converter is capable of transferring the nominal power in both directions, either from the high voltage side to the low voltage side (step-down mode), or from the low voltage side to the high voltage side (step-up mode). Using time-domain analysis it is shown that the converter transfers full power over the entire range of terminal voltages with guaranteed soft switching for all the voltage and power levels. No extra components, active or passive, is used for soft switching. Effectiveness of the modulation scheme in achieving zero current switching was experimentally confirmed.

In this paper DC-AC differential inverters, which are capable of stepping-up the DC voltage in a single-stage, are studied. Due to the reduced number of devices, they are compact, efficient and low cost. Due to their unique characteristics, they can be used in many applications such as PV, UPS and fuel-cell. This paper introduces a new control method which utilizes a different set of voltage references to control the individual DC-DC converters. It is mathematically proven that the method is the optimal solution and improves the performance in terms of loss and device rating. Moreover, the comparison between new and classic method shows that the proposed method decreases the voltage stress, power loss and inductor peak current. Simulation results with PSEVI and experimental results are provided.

This paper investigates the transient response of an islanded microgrid equipped with parallel-connected inverters. The transient performance of the microgrid power sharing mechanism can be strongly affected by the system parameters as well as operating point, which may not be acceptable regarding to the system reliability. To improve the transient performance of the microgrid, a novel transient control strategy based on the static droop characteristics is presented in this paper. To provide the active damping of the low-frequency power sharing modes at different loading conditions, the derivative terms of active and reactive powers have been added to droop functions. The transient droop gains are adaptively scheduled in order to yield desired transient and steady-state response. The proposed controller ensures a stable and robust power sharing performance of the microgrid.

A resonant controller with robust features for digital implementations at low sampling frequencies is proposed. The proposed controller is based on a phase-locked loop (PLL) approach and is derived by transforming the equations of the conventional resonant controller from Cartesian to polar coordinates. The realization of the proposed controller in discrete-time domain involves nonlinear equations with trigonometric functions. This implies slightly higher computational load when compared to the conventional controller. The achieved robustness, however, is significantly high and outweighs the computational issue. In some typical applications, for example, the conventional resonant controller starts losing its accurate performance as soon as the ratio of sampling frequency to the resonance frequency decreases below fifty. This number becomes as low as ten for the proposed controller. The proposed controller is also readily upgraded to become frequency-adaptive; a feature that is desirable in the control systems that operate at uncertain or slowly varying frequency such as the power system.

Planar magnetics are very suitable for automotive applications due to the low profile structure. DC/DC converters in electric vehicles (EVs) use planar magnetics to minimize their size and weight and to increase their ability to withstand mechanical vibrations. Typical planar transformers (PT) in DC/DC converters used in EVs have high inter-turn and interlayer capacitances, which have detrimental effects such as high peak currents, increase voltage overshoot across secondary rectifying devices, and increase leakage current. The paper proposes two winding structures to mitigate the effects of inevitable stray capacitances of planar transformers. In addition, the second strategy integrates the Y-capacitors into the transformer in order to suppress Common-mode (CM) EMI noise generated in the DC-DC converter. The effectiveness of the proposed winding strategy is validated by analytical and experimental results that are presented in the paper.

A two-stage AC/DC converters, generally, consist of an input Power Factor Correction (PFC) in order to improve the quality of the current drawn from the grid, and a DC/DC converter in order to provide galvanic isolation. Since there is a low frequency ripple (2nd Harmonic of the input ac line frequency) in the output voltage of the PFC AC/DC Boost converter due to the power ripple, the voltage loop in the conventional control system should have a very low band-width in order to avoid distortions in the input current waveform. This leads to a very sluggish transient response for the PFC against load variations. This paper presents a new control approach, based on the Control-Lyapunov Function (CLF), which is able to significantly improve the transient response of the PFC stage. Since the dynamics of the PFC stage is highly nonlinear, the optimal controller is derived by solving the Hamilton-Jacobi- Bellman equation. Experimental results from a 3KW AC/DC converter validate the performance of the proposed control method compared to the conventional control technique.

Today, more and more emphasis placed on the energy usage and the electricity supply. Rising energy prices and the effect of greenhouse gases in the past few decades caused subjective improvement and optimization of energy efficiency in the industry. In this regard, many technologies such as distributed generation, energy storage and distribution lead times for energy optimization are presented. We live in a high-technology society and for improving these technologies, electricity share of global energy resources are expected to grow. With a smart production, distribution and energy consumption in the future, we hope to continue the electrical energy posterity. This paper reviews concepts and researches done on optimizing the energy efficiency.

AC/DC converters used in electric vehicles generally consist of two stages: an input power factor correction (PFC) boost AC/DC stage that converts input AC voltage to an intermediate DC voltage and reduces input current harmonics injected to the grid, and a DC/DC converter that provides high-frequency galvanic isolation. Since there is a low-frequency ripple (second harmonic of the input ac line frequency) in the output voltage of the PFC AC/DC boost converter, the voltage loop in the conventional control system typically has a very low bandwidth to avoid distorting the input current waveform. This causes the conventional PFC controller to have slow dynamics against load variations. This paper presents a new control approach that regulates the input power of the converter instead of the output voltage by using an optimal nonlinear control approach based on the Control-Lyapunov Function (CFL). In this paper, it is shown that the proposed controller is able to eliminate the low bandwidth voltage control loop in the conventional PFC controller, thus allowing the front-end AC/DC boost PFC converter to operate with faster dynamic response than with the conventional controller approach. Experimental results from a 3 kW AC/DC converter are presented in the paper to validate the proposed control method and its superior performance.