8 kW QRAS Chopper using SiC Schottky Diode

Abstract

Keywords: silicon carbide schottky barrier diode, peak recovery current I RRM , reverse recovery time t rr , DC-DC converter, soft switching This paper describes a study targeting a 100 kW power range converter to the fuel cell electric vehicle (FCEV). The proposed power converter offers the solutions in both high-power and high-efficiency applications. The power supply consists of new topologies based on Quasi-resonant Regenerating Active Snubber (QRAS) and new devices "SiC schottky diodes", which are already on the market as the next generation of power devices substituted for Si semiconductor devices approaching the theoretical limits of the Si material. The configuration and the performance of 8 kW one-tenth-prototype SiC-QRAS are followed by this report on the successful test evaluation results.In this paper 8 kW prototype-model using IGBTs was made as shown in Fig. 1. We parallel four SiC schottky diodes to increase the current capability to 40 A and assembled it as the output diode D 5 . We tested it and evaluated the effect in the improvement of the efficiency by two fields: new circuit topology and new devices. 98.5% SiC-QRAS was comparatively evaluated from a point of view of the principal difference of the reverse recovery performance. The prototype SiC-QRAS was tested and compared with the conventional Si-QRAS. The output power of 8 kW with the efficiency of about 98.5% was obtained. Fig. 3 shows the result of SiC and Si loss breakdown (measured). Total loss reduction P LM , measured by means of VOAC7413 Iwatsu digital multi-meters, 2011 Yokogawa DC Ammeters and 2215. Yokogawa shunts, is 77 W (= 210 − 133). On the other hand total loss reduction P LP , measured by means of a DA1855A Lecroy high precision differential amplifier, a DXC100A Lecroy probe and WAVEPRO950 Lecroy digital oscilloscope, is 65.5 W (= 257.1 − 191.6). So loss reduction rate proved about 1% in each case. This time we confirmed that SiC-SBD reduced the dynamic power losses drastically and it had been achieved by means of new circuit topology QRAS. Atsuo Kawamura * * Member This paper describes a study targeting a 100 kW power range converter to the fuel cell electric vehicle (FCEV). The proposed power converter offers the solutions in both high-power and high-efficiency applications. The power supply consists of new topologies based on Quasi-resonant Regenerating Active Snubber (QRAS) and new devices "SiC schottky diodes", which are already on the market as the next generation of power devices substituted for Si semiconductor devices approaching the theoretical limits of the Si material. The configuration and the performance of 8 kW one-tenth-prototype SiC-QRAS are followed by this report on the successful test evaluation results.