This paper contains a comparison between three topologies of a three-phase two-level inverter: a quasi-Z-Source inverter, a Voltage-Source Inverter with a Boost Converter and a Voltage-Source Inverter with an interleaved Boost Converter. Experimental results obtained from laboratory tests of equivalent 6-kW 100-kHz inverters based on SiC MOSFETs and Schottky diodes are provided. The following parameters are compared: quality of input inductor current and output phase voltage as well as total power losses in the inverters. The results for these parameters are obtained for input voltage ranging from 325 V to almost 600 V (where feasible), for two sets of equivalent modulation methods (two regular methods and two reduced-loss methods), for a couple of characteristic values of deadtime and for operation both at the maximum value of modulation index and at equal values of voltage across the inverter bridge. Results of the experiments show that the quasi-Z-Source Inverter topology may, at certain conditions, surpass the traditional two-stage inverter topologies in the areas of input inductor current quality, output voltage quality and also power losses (at high values of input voltage). What is needed to obtain that is a careful examination of operating conditions, applied modulation method and deadtime value.

This article presents a novel method for the dynamic measurement of Coss-V_DS characteristic of SiC MOSFET power modules based on the process of charging the output capacitance of the transistors. This technique has been used to determine the Coss-V_DS characteristics of medium voltage SiC MOSFET modules, which allows for the extraction of the capacitive current while switching off the transistor. Based on this measurement method, the influence of the turn-off gate voltage V _GS-OFF on the Coss-V_DS characteristics has been studied, exhibiting an impact on the output capacitance at low drain-source voltages. However, it is shown that the effect of V _GS-OFF on the capacitive current and power loss is limited in this area. Finally, the channel current and the capacitive current distribution within the drain current were determined based on the determined Coss-V_DS in the experimental test at various switched currents and switching speeds. According to the capacitive charge calculations for several cases, the method’s accuracy is high enough to perform switching power loss estimations for medium voltage power modules to be employed in the design of state-of-the-art power converters. Furthermore, the method is very simple, based on basic capacitance equations, and the required experimental setup is very similar to one used in double-pulse tests.

This paper describes a four-leg interleaved DC-DC boost converter built on the basis of Silicon Carbide (SiC) devices (Metal-Oxide Semiconductor Field-Effect Transistors—MOSFETs and Schottky diodes) and improved, low-capacitive magnetic components. A combination of wide-bandgap semiconductors capable of operating at elevated switching frequencies and an interleaving technique brings substantial benefits, such as a cancellation of the input/output current ripples, a reduction of weight, dimensions and increase of power density. The 4 × 125 kHz DC-DC boost converter characterized by a volume of 0.75 dm³ reaches an efficiency above 98.7% at nominal power of 6 kW. A special effort has been made to develop and test inductors with low parasitic capacitance. It is clearly proven that an improved design has an impact on the converter performance, especially on power losses. Reduction of the power losses is higher than 25% in reference to a standard design of the inductors and the efficiency is in excess of 99%.

The paper describes major issues related to the design of a portable SiC-based DC supply developed for evaluation of a high-voltage Marx generator. This generator is developed to be a part of an electromagnetic cannon providing very high voltage and current pulses aiming at the destruction of electronics equipment in a specific area. The portable DC supply offers a very high voltage gain: input voltage is 24 V, while the generator requires supply voltages up to 50 kV. Thus, the system contains two stages designed on the basis of SiC power devices operating with frequencies up to 100 kHz. At first, the input voltage is boosted up to 400 V by a non-isolated double-boost converter, and then a resonant DC-DC converter with a special transformer elevates the voltage to the required level. In the paper, the main components of the laboratory setup are presented, and experimental results of the DC supply and whole system are also shown.

This work presents the experimental validation of a 40 kW electric vehicle (EV) charger. The proposed system comprises two 20 kW modules connected in parallel at the input and output. Each module has two stages—as a grid converter Vienna Rectifier (VR) was chosen, and as an isolated DC/DC stage, two Series-Resonant Dual-Active-Bridges (SRDABs) in input-series-output-parallel (ISOP) configurations were applied. The AC/DC and DC/DC stages were enclosed in 2U rack standard housing. A bipolar DC-link with ±400 V DC voltage was employed to connect both stages of the charger module while the charger’s output is dedicated to serving 800 V batteries. VRs operated at 66 kHz switching frequency and the SRDABs operated at 100 kHz. The converters used in the charger structure were based on silicon carbide (SiC) power devices. The description and parameters of the built hardware prototypes of both—AC/DC and DC/DC—converters are provided. Moreover, the experimental validation of each stage and the whole charging system, including oscilloscope waveforms and power analyzer measurements at nominal power, are included. Such a configuration enables energy conversion with high efficiency without a negative impact on the grid and high-quality grid waveforms.

The paper presents the results of calculations, simulations, and measurements of parasitic capacitance of winding in ferrite inductor suitable for cooperating with 2 kW DC-DC boost converter built using SiC JFET transistors, operating with a switching frequency of 100 kHz. The inductor winding is made of litz wire in a two-layer configuration. The lumped model of inductor winding was adopted. The results of analytical calculations have been compared with the results obtained from experimental investigations based on the resonance effect.