7.5 kW电动汽车碳化硅逆变器设计

Design of 7.5 kW SiC Inverter for Electric Vehicles

第三代功率半导体碳化硅SiC(silicon carbide)具有高耐压等级、开关速度快以及耐高温的特点,能显著提高电动汽车驱动系统的效率、功率密度和可靠性。首先,设计了两电平三相逆变器主电路和带有保护功能的隔离型驱动电路,使用LTSpice仿真分析了门极电阻对驱动性能的影响;其次,建立了逆变器的功率损耗与热阻模型,使用Icepak对散热器进行了散热分析;再次,讨论了PCB板寄生参数对主电路和驱动电路的影响,并提出了减少寄生参数的措施;最后,采用CREE公司的1 200 V/40 mΩ SiC MOSFET制作了1台7.5 kW的实验样机,并给出了测试结果。

The third-generation semiconductor silicon carbide(SiC) has characteristics of high-level withstand voltage, fast switching speed and high-temperature supportability, which can significantly improve the efficiency, power density and reliability of the drive system of electric vehicles. In this paper, the main circuit of a two-level three-phase inverter and an isolated driver circuit with protection function were designed, and the effect of gate resistance on the driver performance was simulated using LTSpice. In addition, the power loss of the inverter and its thermal resistance model were analyzed, and the heat dissipation characteristics of heat sink was analyzed using Icepak. Afterwards, the effects of PCB board’s parasitic parameters on the main circuit and the driver circuit were discussed, and the measures to reduce these parasitic parameters were also proposed. Finally, a 7.5 kW prototype was fabricated with 1 200 V/40 mΩ SiC MOSFETs made by CREE, and the test results were given.