Ensuring grid stability with increasing penetration of inverter-based resources requires robust Grid Forming (GFM) control methods. Droop control is a prevalent method, but its reliance on low-pass filters (LPF) for power calculations can limit performance and responsiveness. To address this, Virtual Oscillator Control (VOC) employing Andronov-Hopf principles offers a promising alternative while retaining the simplicity and load sharing capabilities of droop control. This paper analyzes a state of art Andronov-Hopf VOC, demonstrating its reliability when connected to a modern grid consisting of Renewable Energy Sources (RES) and Battery Energy Storage Systems (BESS). MATLAB/Simulink simulations demonstrate the controller's ability to maintain microgrid stability within acceptable limits while exhibiting droop-like characteristics during islanding operation. This paper focuses solely on islanding operation; grid-tied operation is beyond the scope of this work.

Hybrid inverters are typically designed within the kilowatt range to harness the combined power of multiple PV panels and a battery system for supplying loads. However, most conventional hybrid inverters are incompatible with single PV panels due to their low voltage output. In this paper, a novel generation of hybrid microinverters is introduced, tailored to accommodate the power and voltage specifications of single PV panels. The proposed hybrid microinverter design integrates a bidirectional CLLLC converter to elevate the low voltage from the PV and battery to the high voltage level of the DC-link. Furthermore, a conventional GaN-based buck-boost converter is devised to facilitate battery charging via the PV. This approach entails packaging the battery, PV, and hybrid inverter together, resulting in the creation of the first PV AC module capable of delivering AC voltage directly from the PV panel output. To validate the effectiveness of the proposed system, a 700W hybrid microinverter was constructed and subjected to testing in this study.

This paper introduces a novel hybrid bidirectional DC-DC converter designed for energy storage applications, featuring high voltage conversion ratios. Utilizing a hybrid approach, the converter benefits from enhanced controllability and versatility, employing switched inductors and capacitors. During discharging and charging modes, the inductors are configured either in series or parallel, enabling the converter to achieve significant voltage gain. Furthermore, zero-voltage switching (ZVS) is attainable during both turn-on and turn-off dead times for select power switches, facilitating soft switching and thereby enhancing converter efficiency. The operational principles of the converter are thoroughly examined for both stepup and step-down modes, elucidating the theoretical equations governing its operation. Finally, a 1 kW (50V/800V) converter is simulated to validate its performance.

A three-port multilevel inverter with two DC ports and an AC port using Flying Capacitor Multilevel (FCML) design based on Gallium Nitride (GaN) switches is proposed in this paper. Recently, FCML inverter has shown a superior ability for power conversion with high power density, improved Total Harmonic Distortion (THD), and efficiency. The presented three-port multilevel inverter fits various applications such as battery and photovoltaic (PV) grid integration and standalone AC load. The proposed inverter is experimentally verified by building a 3-kW prototype using GaN switches which include two 4-level FCML converter paths, each share the same bus capacitor (Cbus), which links them together. One FCML path is 1 kW that incorporates an unfolder for the DC-to-AC conversion and has achieved a peak efficiency of 98.2% with AC voltage and current THDs of 1.26% and 1.23%, respectively. While the second FCML converter path is 2 kW used for the DC-to-DC conversion and has achieved a 99.43% peak efficiency.

This paper proposes a double Maximum Power Point Tracking (MPPT) algorithm for achieving maximum efficiency of a grid-tied phase-shifted dual-PV LLC converter using the Adaptive Neuro-Fuzzy Interface System (ANFIS). The algorithm can extract maximum power from Photovoltaic (PV) panels under various weather conditions and partial shading. This dual MPPT algorithm generates switching frequency and phase shift through ANFIS to regulate the power flow using both Frequency Shift Modulation (FSM) and phase-shift modulation (PSM) techniques simultaneously. Here the ANFIS model is developed using the LLC converter’s input-output data set for each PV panel to train the neural network while the fuzzy rules ensure the optimum output using different membership functions. The second controller on the grid side maintains the DC link voltage to a fixed level as well as ensures grid power injection with minimal harmonic distortion. Derivation of this dual-MPPT algorithm and verification of the proposed closed-loop system is presented in this paper.

A novel four-port LLC converter for renewable energy application is proposed in this paper. The converter interfaces two Photovoltaic (PV) panels and one battery on the primary side whereas load on the secondary side. This topology allows three energy ports to share a single resonant tank through a hybrid full-bridge structure. The battery port of this converter is bidirectional to balance the load demand and energy generation from the PVs. Two PVs and battery ports are regulated via phase-shift modulation (PSM) to harvest maximum power from the PVs and control the battery operation, whereas the load is regulated by the Switching Frequency Modulation (SFM) technique. All operating scenarios with their steady-state waveforms, analysis, and control scheme are discussed. Finally, a simulation study is carried out to validate the operation of the proposed topology.

This paper presents a step-by-step analysis of the Linear Active Disturbance Rejection Control (LADRC) for single-phase Uninterruptible Power Supplies (UPS) application. In UPS application, the regulated output voltage with low Total Harmonic Distortion (THD) under different load conditions and disturbances is the desirable. To achieve this goal, LADRC is appropriate since it uses the state observer similar to the modern control theory. Also, this control method inherits the PID controller’s simplicity, it is not a model-based controller. Moreover, it is useful for experimental platforms since it can control the system even there was weakness in the modeling of the system. Finally, a 1kW single-phase UPS has been simulated in Matlab/Simulink to verify the theoretical analysis as well as the operation of the LADRC in this application.

In this paper, a Bidirectional DC-DC Converter (BDC) for the Electrical Vehicle (EV) application is proposed. The converter benefits the advantages of both switched-inductor and switched-capacitor converters. The proposed converter has wide voltage gain range, low voltage stress on the power switches, and common ground between the grounds of the input and output sides. In addition, synchronous rectification is utilized to achieve Zero Voltage Switching (ZVS) during turn on and turn off dead time, which enhance the efficiency of the converter. The operating principle of the converter, steady-state analysis, and all devices’ voltage and current stresses are derived. Finally, a 1 kW converter with constant high-voltage side (400V) and very low-voltage side (24V) has been designed and simulated.

This paper presents a control strategy for a novel three-port DC-DC-AC converter based on dual active bridge and interleaved boost topology connected to PV, battery, and grid. We use model predictive control (MPC) framework to provide control actions in both islanded and grid-connected mode of operation. The control objectives are output voltage regulation in islanded mode when converter power flows between port-1 and port-3, maximum power point tracking (MPPT) during operation between port-1 and port-2, and active and reactive power control while operating in grid-connected mode. The different power flow modes of the converter have been represented as discrete time state-space models and then, cost functions have been developed. Convex optimization of the cost functions provides optimal control inputs and thus, the objectives are fulfilled. The simulation performed in Matlab/Simulink validates the effectiveness of the developed control method using MPC for the novel three-port converter (TPC).

The switching frequency is among many design parameters of grid-tied single-phase H-bridge sinusoidal pulsewidth modulation (SPWM) microinverters. The selection of the switching frequency is a tradeoff between improving the power quality by reducing the total harmonic distortion (THD) and improving the efficiency by reducing the switching loss. This paper proposes two algorithms to optimize both the power quality and the efficiency of the microinverter by using a frequency tracking technique that requires no hardware modification. The first algorithm tracks the optimal switching frequency for maximum efficiency at a given THD value, while the second maximizes the power quality of the H-bridge micro-inverter by tracking the switching frequency that corresponds to the minimum THD. Experimental verification followed by results evaluation are presented.

This paper presents a single-stage three-port microinverter for single-phase grid-connected PV applications. A battery in the third port is dedicated to store the additional power generated from the PV panel. The battery also operates as a backup power source to compensate for the power mismatch between the source and the grid. The integrated three-port inverter operates under soft-switching technique so that the switching losses of the high frequency primary and secondary switches are negligible. To verify the theoretical analysis of the proposed topology, a 100-W three-port microinverter was designed and simulated.

A variable step-size switching frequency selection algorithm with fast convergence performance for power converters is presented in this paper. The algorithm can automatically track and detect the optimal switching frequency for a DC-DC converter in order to achieve the highest possible power conversion efficiency. This technique is theoretically analyzed and developed based on synchronous buck converter loss model and its behaviors. A digital control system is designed to apply the selected optimal switching frequency to modulate the PWM duty cycle accordingly. An experimental prototype is built to verify the proposed algorithm and validate the theoretical efficiency improvement.

This paper comprehensively discusses the multiphase power converter design and introduces new control schemes in dynamic operations, which are now used to supply the power for modern Multi-Core processor (MCP) and multiprocessor System-on-Chip (MPSoC). With the aggressive motivation to boost dynamic power efficiency, the design specification of the VR is pushing the physical limitation of the multiphase converter design and the component stress as well. In this paper, the operation modes and PWM drive interface to achieve phase shedding are first illustrated. Robust driver operation is ensured when exiting the tri-state for long time. Nonlinear control scheme is introduce to minimize the voltage excursion during load transient. CdV/dt compensation for removing the AVP effect and novel nonlinear control scheme for smooth transition are proposed for dealing with fast voltage positioning. For experimental verification, a 400 W six phase synchronous buck converter is implemented with the proposed schemes.

The interactive technical electronic book, TechEBook, currently under development at the University of Central Florida (UCF), introduces a paradigm shift by replacing the traditional electrical engineering course with topic-driven modules that provide a useful tool for engineers and scientists. The TechEBook comprises the two worlds of classical circuit books and interactive operating platforms such as iPads, laptops and desktops. The TechEBook provides an interactive applets screen that holds many modules, each of which has a specific application in the self learning process. This paper describes one of the interactive techniques in the TechEBook known as Symbolic Circuit Solver (SymCirc). The SymCirc develops a versatile symbolic based linear circuit with a switches solver. The solver works by accepting a Netlist and the element that the user wants to find the voltage across or current on, as input parameters. Then it either produces the plot or the time domain expression of the output. Frequency domain plots or Symbolic Transfer Functions are also produced. The solver gets its input from a Web-based GUI circuit drawer developed at UCF. Typical simulation tools that electrical engineers encounter are numerical in nature, that is, when presented with an input circuit they iteratively solve the circuit across a set of small time steps. The result is represented as a data set of output versus time, which can be plotted for further inspection. Such results do not help users understand the ultimate nature of circuits as Linear Time Invariant systems with a finite dimensional basis in the solution space. SymCirc provides all simulation results as time domain expressions composed of the basic functions that exclusively include exponentials, sines, cosines and/or t raised to any power. This paper explains the motivation behind SymCirc, the Graphical User Interface front end and how the solver actually works. The paper also presents some examples and results to better explain the concept.

A new digital control scheme aiming to improve the transient response of an FPGA-based digitally controlled DC-DC converters is presented in this paper. The proposed approach enhances the transient response by dynamically controlling the ramp of the Digital Pulse Width Modulator (DPWM) unit through applying either linear or nonlinear shift to the conventional ramp-based DPWM. This allows the compensator to reach steady-state faster. The advantages and disadvantages of both techniques are presented and weight against improvement on transient response. Detailed analysis, simulation results and experimental waveforms are presented to verify the concept.

This paper presents an improved mathematical and simulation model for Solar Photovoltaic (PV) cells and compares it to an existing model. The model is able to simulate both the I-V characteristics curves and the P-V characteristics curves. The model is used to study different parameters variations effects on the PV array including operating temperature and solar irradiation level The results of the PV characteristics curves are compared to the curves provided by BPSX150 PV module datasheet. Matlab®/Simulink® software is used to implement the models and obtain the simulation results.

As interest in renewable energy systems with various sources continues to grow, there is a strong need for integrated power converters that are capable of interfacing and concurrently controlling several power terminals. Meanwhile, energy storage is required to compensate for the mismatch between the sourcing and loading power patterns over a regular operational cycle. Therefore, different operational scenarios and modes exist during a regular operational cycle. This necessitates an intelligent power management and a mature and advanced control strategy in order to boost energy harvesting, protect the battery and increase overall system functionality, reliability and efficiency. The proposed four-port converter interfaces one photovoltaic (PV) panel input port, one wind turbine input port, one bi-directional battery port and an isolated output port. It has the advantage of low switch count, high power density and high efficiency. Wind and PV Maximum Power Point Tracking (MPPT), battery charge algorithm and bus voltage regulation are efficiently managed by a mature control structure.

A switching frequency auto-tuning digital controller for a power converter with adaptive step-size is presented in this paper. The controller automatically tracks and finds the switching frequency of a power converter in order to achieve highest power conversion efficiency under variable conditions and load. The adaptive controller utilizes a proposed adaptive variable-step-size function to improve the convergence speed and convergences error. The auto-tuning controller with the proposed adaptive step-size function is discussed and verified in this paper.

An adaptive digital controller with maximum efficiency point tracking to optimize DC-DC converter switching frequency is presented in this paper. The adaptive-frequency-optimization (AFO) method changes the DC-DC converter switching frequency while tracking the converter minimum input power (maximum efficiency) point under variable conditions including variable load and variable input voltage. The AFO digital controller continuously finds the optimum switching frequency that result in the minimum total loss while converter parameters and conditions vary. In this paper, the AFO method is discussed analyzed and its digital control algorithm and experimental implementation are presented.

An adaptive digital controller with maximum efficiency point tracking to optimize the FETs' switches driving-voltage is presented in this paper. The driving-voltage-optimization (DVO) method adaptively changes the FETs driving voltage magnitude while tracking the converter minimum input current/power (maximum efficiency) point. The DVO digital controller continuously finds the optimum FETs driving voltage that will result in a minimum total combined FETs driving and conduction losses while converter parameters and conditions vary. In this paper, the DVO method is discussed analyzed, and its digital control algorithm and experimental implementation are presented.

Digital compensator design is an important and essential step to achieve stable power converter with good steady-state and dynamic performance. Generally there are two digital controller design approaches: The digital redesign approach and the direct design approach. In this paper, hybrid discretization (s-to-z transformation) approach is applied to power converters digital controllers/compensators to achieve better redesigned controller. This is because of the fact that two or more transformation methods with opposite warping effects can be hybridized when discretizing the analog transfer function to reduce the total warping effect. Hybrid discretization can be implemented by different ways, of which three were discussed in this paper. Theoretical, design and simulation results show that better controller/compensator design results, which are closer to the analog case, can be achieved using hybrid discretization technique in the digital redesign approach rather than using single transformation method.

Future generation of microprocessors will require high performance Voltage Regulator Modules (VRMs) that produce tightly regulated low supply voltage with very small deviation window and able to respond very quickly to a large and continuous load transients at high output current while maintaining a high power density. On one hand, the current drawn from the VRM by the microprocessor is continuously changing since it depends at the current use of the microprocessor. On the other hand, High Frequency VRMs as any Power Electronics System is a complex combination of linear, nonlinear, and switching elements that is required to have fast dynamics. Moreover, this complex combination is also real-time system that needs to continuously and instantly monitor and respond to the load changes (the microprocessor). A high performance basic control loop is essential to follow up with such transients. Such controller design is usually complicated especially since it requires high knowledge of the converter and its behavior and accurate converter model that includes nonlinearities and parameters and components variations. DSP has many advantages over the analog circuits when it comes to applying high performance sophisticated control techniques such the simplicity in applying sophisticated control algorithms and modifying them via software revision, lower environmental and noise sensitivity, and less components count. In this paper, a DSP setup to be

The analysis for a given soft-switching DC-DC converter family can be generalized using the switching-cell of that family leading to a number of generalized equations with a transformation table. In this paper, the concept of generalization and step by step procedure for the generalized process are discussed and applied to selected soft-switching families such as ZVS-QRC, ZCS-QRC, ZCS-CC QSW, ZVS-CV QSW, ZCT-PWM, and ZVT-PWM. Also, it has been noted that all the analyzed families have one generalized transformation table. It will be shown that the generalized analysis leads to several advantages.

A single-stage power factor correction converter with soft-switching is proposed in this paper. The topology of this converter is derived by adding a resonant circuit to an existing Single-Stage, Single-Switch Power Factor Correction (S/sup 4/ PFC) converter. As a result, zero-voltage-switching and zero-current-switching are achieved for the main switch and the auxiliary switch, respectively. High frequency operation of the proposed converter makes it possible to minimize the ac-dc power supply in size and weight. The proposed converter uses a grounded auxiliary switch so that the isolated driving circuit is not required. The simplified driving circuitry will again improve the overall efficiency and power density. Practically, the direct driving schemes of both the main and the auxiliary switches will allow the proposed converter to operate in even high switching frequency and have good regulation capability.

In this paper, a non-ideal PWM switch model considering conduction losses is developed. This issue was considered in the past only with the assumption that the inductor current ripple is negligible compared with its average value. Derivation of the new model is based on the energy loss invariant principle. The resulting model can be applied to simulating large inductor current ripple conditions. Accuracy of the proposed model is verified through Pspice simulation using the buck and boost converters.