Silicon Carbide Switching Devices Research Articles

High-efficiency design of a grid-connected PV inverter based on interleavedflyback converter topology

The importance of efficiency in photovoltaic (PV) inverter applications makes the topology selection as the critical first step. Due to the low efficiency concern, flyback converter is not the preferred topology in kilowatt range in spite of its galvanic isolation, low cost, and small size advantages. Therefore, the objective of this research is to change the perception in favor of flyback converter by designing a flyback-topology-based PV inverter at 2.5 kW with high efficiency. The enhancement in efficiency is achieved mainly by using silicon carbide switching devices, designing ultrahigh-efficiency flyback transformers with extremely low leakage inductance and by implementing a prototype with the lowest parasitic components. As a result, the efficiency of the experimental inverter is measured as 95.82 %. Moreover, the low cost and small size objectives are also maintained with very good grid side performance. Consequently, the experimental results demonstrated that the flyback-converter-topology-based inverters can be successfully implemented at high power with high efficiency and with high commercial value.

An Amorphous Alloy Magnetic-Bus-Based SiC NPC Converter With Inherent Voltage Balancing for Grid-Connected Renewable Energy Systems

This paper presents an amorphous alloy magnetic-bus-based neutral point clamped (NPC) converter for grid-connected renewable generation systems. In the proposed system, the amorphous alloy high-frequency high-power density multi-winding magnetic bus generates balanced dc supplies for the five-level (5L) NPC converter for high-quality power conversion. Compared to the traditional NPC converter topologies, the proposed magnetic-bus-based architecture does not require any control circuit for voltage balancing of the series connected capacitors. The magnetic bus inherently overcomes galvanic isolation issues and may reduce the size of the boosting inductor. In this paper, a finite control set model predictive control algorithm is derived to control the grid-connected 5L-NPC inverter for multilevel voltage synthesizing, while achieving the user-defined active and reactive power values. To verify the proposed concept, a simulation model is developed and analyzed in MATLAB/Simulink environment. To validate the technology, a scale d-down prototype test platform is developed in the laboratory with silicon carbide switching devices, which achieves high blocking voltage, low power dissipation, high switching frequency, and high-temperature operation. Based on the simulation and the experimental results, it is expected that the proposed converter will have a great potential for widespread application in renewable generation systems including superconducting generator-based wind turbines.

Efficiency Evaluation of the Modular Multilevel Converter Based on Si and SiC Switching Devices for Medium/High-Voltage Applications

The modular multilevel converter (MMC) is the most promising converter topology for medium- and high-power applications. One of the main concerns in the operation of the MMC, particularly for high-power applications, is its efficiency, which should be maximized. Silicon Carbide (SiC)-based devices have the potential to provide significant efficiency improvement compared with silicon devices. However, the possibility and impact of using SiC-based devices instead of silicon devices for high-power conversion have not been thoroughly explored. This paper reports on the results obtained from a detailed study to evaluate the performance of MMCs based on medium-voltage SiC MOSFETs and diodes with hybrid MMCs that employ silicon IGBTs and SiC diodes. The results are based on detailed circuit simulations that use simple physics-based circuit models. The study suggests the potential for significant efficiency gain for MMCs based on SiC power devices.