SiC MOSFET Loss Analysis And Research Based On Half Bridge Inverter

The performance of modern power electronic converters is limited by many factors, including the limited performance of power electronic devices. For example, in a traditional inverter, the large conduction resistance of Si MOSFET results in large conduction loss when working under high-power condition. Meanwhile, due to the need of freewheeling diode, the reverse recovery performance of diode limits the switch frequency. Lower switch frequency would result in a larger volume of the filter. The new type SiC MOSFET has lower conduction resistance under the same voltage. Besides, it has a larger band-width, higher critical breakdown field strength, higher saturated electron mobility and higher thermal conductivity compared to traditional Si MOSFET. Therefore, it brings opportunity for the development of new power electronics technology.In this thesis, the characteristics of Si MOSFET, SiC MOSFET and Si IGBT are compared. The advantages of SiC MOSFET working under high-power condition are demonstrated. The influences of drive resistance and parasitic inductance are analyzed as well so that the requirements of the drive circuit are demonstrated. Double-pulse test for GE12N20L(1200V/20A) under 25℃ and 125℃ validate the advantages that SiC MOSFET has better reverse recovery performance and less switching loss.Secondly, we comprehensively describe the switch state under different switch period of half-bridged inverter. The loss model of half-bridged inverter based on SiC MOSFET is proposed to evaluate the efficiency of the system and distribution of loss.Finally a 2kW SiC MOSFET half-bridge inverter prototype is made. Its performance under different switching frequency and environment temperature validates that SiC MOSFET can help the system get higher efficiency. Meanwhile, it validates the accuracy of the system loss model.