Performance Analysis and Experimental Validation of 240°-Clamped Space Vector PWM to Minimize Common Mode Voltage and Leakage Current in EV/HEV Traction Drives
Hafsa Qamar, Haleema Qamar, Raja Ayyanar
Abstract
High switching frequency inverters in hybrid electric vehicle/electric vehicle (HEV/EV) drivetrains present problems such as common mode voltage (CMV) and leakage current that have negative impacts on the performance of the drivetrain. Various reduced CMV PWM (RCMV-PWM) methods have been introduced in the literature that reduces the CMV but typically at the expense of increased total harmonic distortion (THD) and switching loss simultaneously. In this article, a low-loss PWM method called 240°-clamped space vector PWM (240CPWM) is discussed in terms of its CMV and leakage current characteristics. It is analytically shown that 240CPWM reduces the peak CMV and the number of CMV pulses in a switching period by 66.7% each, and RMS CMV by 21%, while simultaneously reducing the switching loss by 85%, and achieving similar THD at maximum speed (and lower THD at other speeds) as compared to conventional space vector PWM (CSVPWM). Detailed analysis of CMV and leakage current is presented for 240CPWM and compared with CSVPWM and discontinuous PWM (DPWM1) with constant and variable dc-link voltage control. Experimental results from a 10-kW hardware prototype are presented that conform to the analytical discussions and validate the superior performance of 240CPWM.