碳化硅功率器件对电机系统电磁干扰和损耗影响机理研究

High efficiency, high power density and high temperature operation of the motor drive system is extremely desirable in aerospace and electric vehicle propulsion systems. This cannot be easily realized by directly replacing Si devices with wide bandgap (WBG) device such as SiC MOSFETs making WBC devices suitable for aerospace application. SiC motor drive is still in the research stage. Considering the fast switching speed (dv/dt and di/dt ) and low threshold voltage characteristics of SiC, this project initiates to investigate the technical difficulties of replacing conventional Si devices with SiC devices in motor drive. Several aspects will be studied: Frist, the parasitic parameters of devices, cables, and motors will be analyzed and extracted. Second,various factors affecting the switching characteristics of the SiC MOSFETs with motor load will be studied, and a precise mathematical model considering these factors will be established. Thrid, the EMI source modeling for SiC devices will be explored, and equivalent CM and DM circuits will be modeled as well. Based on the EMI circuit model, different attenuation methods will be studied. Then, the impact of harmonics introduced by SiC switching on motor's copper losses and iron losses will be studied. Based on the above research, an overall design and optimization of the whole drive system and motor will be proposed considering overall system efficiency and EMI performance. The proposed design method will provide theoretical guidelines and facilitate the drive system design the aerospace application and electric vehicle application.

基于SiC MOSFETs的电机驱动系统具有高效率、高功率密度和高温运行等特性，是航空航天器以及电动汽车电推进最佳选择之一。SiC电驱动研究处于起步阶段，本课题拟从SiC快速的开关速度、阀值电压低等基本特性出发，围绕SiC取代电驱动中Si器件存在的理论和技术难点问题开展研究，包括：分析和提取器件、电缆和电机的寄生参数；理论分析电机系统中SiC开关特性的各影响因素，进行敏感性分析，建立考虑影响因素的SiC精准数学模型；剖析SiC引起系统传导电磁干扰（EMI）的内在机制,建立其共模和差模干扰等效电路，探索EMI抑制方法；研究SiC逆变器高次谐波对电机铜耗和铁耗的影响机制；形成电机-驱动器一体化优化设计和一体化优化控制方法，研制兼具全局效率高和电磁兼容性强的SiC电机系统，为其在航空航天以及电动汽车等领域的应用提供理论基础和技术支撑。

由于SiC MOSFETs 在高效率、高温、高频等方面的巨大应用潜力，基于 SiC 功率器件的电机驱动器也具有高效率、高功率密度、高温运行等优势。然而SiC器件开关特性的影响规律和内在机理、SiC器件高速开关引起传导EMI的内在机制和相应抑制EMI方法以及SiC逆变器对电机损耗的影响机理等问题依然有待研究。.针对SiC MOSFETs的开关特性和损耗模型，分析了SiC MOSFETs半桥在电机系统中的瞬态换流过程，建立了SiC MOSFETs多时间尺度瞬态模型和考虑各寄生参数的损耗模型，实验验证了该模型的正确性。分析了电压源型门极驱动电路、电流源型驱动电路两种驱动电路拓扑下SiC MOSFETs的损耗温度特性，并进行对比。分别设计了电压源型、电流源型门极驱动电路的硬件实现，对所提出规律进行了实验验证。为了明晰基于SiC MOSFETs驱动的电机损耗，建立了SiC驱动器电压输出畸变的数学模型，从导通管压降、死区时间、开关延迟时间、输出电容、电压过冲等多方面对输出电压畸变进行全面的解析；进而分析高频基波和高次谐波对电机铜耗和铁耗的影响。针对SiC MOSFETs电机驱动系统的传导EMI，理论分析了SiC电机系统传导EMI产生机制，研究了高频下电机系统各部分寄生参数引起的干扰潜在通路，实验研究了SiC MOSFETs电机驱动系统传导干扰影响因素的敏感性。建立了SiC电机驱动系统的共模和差模EMI等效电路模型，提出了SiC MOSFETs电机驱动系统的EMI抑制方法并实验验证。利用上述分析的 EMI 等效电路模型和电机损耗模型，从整体角度对电机和逆变器进行优化设计，使得驱动器、电缆和电机等组成部分相互优化匹配。提出了兼顾EMI、效率和轴电流的一体化优化控制策略，并研制了一套高性能SiC MOSFETs电机驱动系统。设计了SiC MOSFETs的门极主动控制电路，在没有增加EMI发射水平的基础上降低了器件的开关损耗并抑制了电流电压的过冲、振荡。