The Switching Performance Comparison And Application Research Of 1.2kV SiC Devices

With the global energy development and utilization, the high efficiency utilization of energy has attracted extremely attention. The efficiency of traditional silicon devices in most high-power equipment has continuously improved, it has reached the limitation of silicon devices. A new generation of silicon carbide materials inoculating, Si C materials have the advantages of high breakdown electric field, the large band gap, and high thermal conductivity. This makes the silicon carbide devices having more prominent comprehensive performance than silicon devices. Now the new devices have replaced partial traditional ones and expressed excellent switching performance in lots of fields. Especially at the 1.2kV and 1.7kV middle voltage market, the silicon carbide MOSFET and silicon carbide BJT have the more advantages over the silicon IGBT and MOSFET. Therefore, the performance of SiC devices arouse a progressively heated research.Their performance is very close, the study of SiC devices is usually concentrated on the hard swithing process, such as how to slow down the spikes and resonances and optimize the compromise of switching speed and switching loss. But the result is not perfect. It is difficult to avoid these problems, which the soft switching technology could effectively alleviate the contradiction.This paper mainly analysis and compare two different Si C devices. At aspect of the static state switching, we analyze the output characters, specific-resistance features and conduction loss of the 1.2kV 4H-SiC MOSFET and 4H-SiC BJT;at aspect of dynamic state switching, we have simulated and optimized the main parameters for the 1.2kV 4H-SiC MOSFET and 4H-SiC BJT. According to the optimized parameters, we set up the dubble pulse test experiment, and compared the simulated switching losses with experimental switching loss at the same voltage and different current degree for the two devices, what’s more, we also tested the experimental switching loss at same power level for both. The results of simulated and tested are coincidental, and verify the accuracy of simulation mode of SiC devices.At the same power level, the turn-on loss of SiC MOSFET is lower than SiC BJT’s while the turn-off of SiC BJT is better than SiC MOSFET’s.Due to effect of contradiction between switching speed and the high dv/dt and di/dt rates produced by the circuit parasitic elements. SiC devices suffer from lots of issues which prevent the device from full utilization of the maximum switching speed. Accordingly, With soft-switching technique such as resonant DC link circuit, we designed a Zero-Voltage-Switching Quasi-Resonant Converter(ZVS QRC). After the simulated, we find the switching loss of two SiC devices in the soft switching circuit has achieved tremendous improvement over it in the hard switching circuit. It can significantly decrease the high dv/dt and di/dt rates of the switching process of devices. To be specific, the switching loss of two SiC devices is extremely low. At the same power level, the soft switching turn off loss of Si C MOSFET and SiC BJT is 44.3 percent and 30.5 percrnt of hard switching turn off loss,the turn on loss of them has reduced 99.9% and 99%; the soft switching loss of SiC MOSFET has reduced 15% of SiC BJT.therefore, the hard switching and soft switching performance of Si C MOSFET is more better.