H-bridge quasi-Z-Source (HBqZS) converter became attractive solution for integration of photovoltaic (PV) panels to low voltage grid due to single stage power conversion. In this paper, a comparison analysis of two power semiconductor technologies, SiC-Mosfet and Si-IGBT, applied to HBqZS converter is presented. The comparison includes: efficiency and losses distribution among converter's components, impact of switching frequency on the parameters of passive components, as well as cost for both technologies. Finally, hardware SiC-Mosfet model is compared with simulation analysis.

Silicon Carbide (SiC)-based single-phase quasi-Z-source inverter (qZSI) is proposed in this paper to provide a high power density and cost benefit solution for the Photovoltaic (PV) power application. Bulky qZS impedance network is unavoidable in conventional single-phase qZSI even with SiC power devices, due to handling double-line-frequency (2ω) ripple. The design of SiC-based single-phase qZSI is addressed in this paper through power loss evaluation and impedance parameters determination with active power filter's phase leg for compensting the 2ω ripple. All passive components are small in size and weight under the high switching frequency of SiC devices. Power devices' losses of SiC and Si-based inverter are compared. Simulation results at the designed parameters are introduced to validate the proposed solution.

Modular multilevel converter (MMC) is a promising new topology for high-voltage applications. The MMC is made of several identical submodules. For proper operation, each submodule can be considered as a controlled voltage source where capacitor's voltage should be maintained at a certain level. Besides, the minimization of the circulating current, which does not flow to the load, is crucial for achieving stable and efficient operation of the MMC. The interrelations among the load current, circulating current, and capacitor voltages complicate the MMC control. This paper aims to achieve stable and balanced voltage and current control with reduced circulating current in various operating conditions. The proposed control uses weighted model predictive control based on a normalized cost function to select the inverter switching patterns, which control the load current, while minimizing voltage fluctuation and circulating current. The weighting factors were selected based on minimizing the load-current total harmonic distortion (THD) and circulating current. The analysis is conducted on a low-power case study of single-phase four-cells MMC with possible extension to higher number of cells. The low-power three-level prototype is designed and built to validate this proposed method. Theoretical analysis, simulation, and experimental results are presented and compared. Parameter sensitivity analysis was also conducted. They all confirm the effectiveness of the proposed control method.

This paper presents a finite-control-set model predictive control (FCS-MPC) for grid-tied packed U cells (PUC) multilevel inverter (MLI). The system under study consists of a single-phase 3-cells PUC inverter connected to the grid through filtering inductor. The proposed competitive topology allows the generation of 7-level output voltage with reduction of passive and active components compared to the conventional MLIs. The aim of the proposed FCS-MPC technique is to achieve, under various operating conditions, grid-tied current injection with unity power factor and low total harmonic distortion while balancing the capacitor voltage. Parameters' sensitivity analysis was also conducted. The study is conducted on a low-power case study single-phase 3-cells PUC inverter and with possible extension to higher number of cells. Theoretical analysis, simulation, and experimental results are presented and compared.

Deadtime effects in PWM inverters are nonlinear and depend on the switching frequency of the inverters and the types of power devices, snubber circuits, and loads. Several deadtime compensation methods were proposed in the literature where some are based on the polarity of reference current. In these cases, the actual current ripples around the zero crossing cause inverter output voltage distortions. This paper discusses and implements a deadtime and current zero crossing effects compensation method based on Iterative Learning Control (ILC) technique. Preliminary off-line experimental results confirmed the feasibility of the proposed method. Note that, beside the compensation for the above effects, the proposed technique may be also used to compensate for the effects caused by snubber circuits and switching devices imperfections such as voltage drop and on/off delay.

This paper proposes a flexible predictive control strategy for flying capacitors based Multi-Level Inverters (MLIs). The proposed controller, applied for a Flying Capacitors Inverter (FCI) and a Modular Multilevel Converter (MMC), is offering the possibility of furthering the capacitor voltages tracking, load and circulating current tracking, or a trade-off between all state variables tracking (capacitor voltages should be controlled in order to ensure a proper operation of the MLIs). This trade-off is made possible by the mean of weighting factors introduced in the cost function calculation. Theoretical analysis, simulation and experimental results are described in this paper.

This paper proposes a new controller for a grid connected power conditioning unit (PCU). The PCU consists of a flying capacitors inverter (FCI) connected to the grid through an inductor and a step-up transformer. A hybrid model of the PCU is derived using a newly improved commuted Bond Graph (BG) method. The derived hybrid model is an explicit standard model valid for all FCI configurations. A weighted real-time predictive controller is proposed and its implementation is made simple using the developed hybrid model. The weighted predictive algorithm transfers the power to the grid by controlling the current with unity power factor and lower harmonic distortions. Modelling using the BG, theoretical analysis, simulation and experimental results are described in this paper.

This paper proposes a weighted Real-Time Digital Feedback Control for a grid connected Distributed Generation (DG) system (gas turbines, fuel cells, photovoltaic, wind...). The DG source is connected to the grid through a Power Conditioning Unit (PCU) consisting of a multilevel Flying Capacitors Inverter (FCI), an inductor, and a step-up transformer. The proposed controller is predictive type offering the possibility of furthering the capacitor voltages tracking, load current tracking, or a trade-off between all state variables tracking (capacitor voltages should be controlled in order to ensure a proper operation of the FCI). The Weighted Predictive Controller (WPC) transfers the power to the grid, even under grid voltage variation (sag or swell) due to its Voltage Ride Through (VRT) capability by controlling the current with unity power factor. Theoretical analysis, simulation and experimental results are described in this paper.

Recent developments in semiconductor technology enabled developing converters with ultra high switching frequency to achieve high power densities which increased the complexity of designing optimized gate drive circuits. This paper discusses latest developments in gate drive technologies including level-shifting, isolated power sources and drive circuit techniques which are further investigated by simulation and compared to be used in future gate drive circuits. Special considerations for designing gate drive circuits have been mentioned and foundation laid out for further optimization of their performance. Finally a new gate drive circuit was proposed based on mentioned developments and challenges discussed to bring proposed gate drive circuit into practical industrial applications.

PV energy generation has been one of the most active research areas in the past decades due to its inexhaustibility and environmental-friendly aspects. However, the great deal is to utilize the solar energy effectively through power electronics converters (conditioners) to meet the increasing demand for load. This paper proposes an experimental photovoltaic (PV) power conditioning system with line connection. The conditioner consists of a Flying Capacitors Inverter (FCI) feeding an inductive load and connected to the grid through transformer. A hybrid model of the power conditioning system is derived using the electrical equations and verified by a commuted Bond Graph (BG) method. The obtained hybrid model is an explicit standard model valid for all FCI configurations. An original controller based on weighted real-time predictive control technique is designed and its implementation is made simple using the derived hybrid model. The control algorithm transfers the power to the grid by controlling the current with unity power factor. The proposed controller transfers the power to the grid with lower harmonics content. The theoretical analysis, the simulation results and the experimental results are described in this paper.