Impact of modulation schemes on DC-link capacitor of VSI in HEV applications

A simplified equivalent circuit of electric powertrain system of hybrid electrical vehicle (HEV) is proposed to research and investigate into the impact of pulse width modulation (PWM) strategies of voltage source inverter (VSI) on the DC-link capacitor in HEVs. Then, analytical solutions to the switching function are introduced based on space vector PWM (SVPWM) and discontinuous PWM (DPWM) schemes. Furthermore, the DC-link capacitor current is characterized with analytical solution and simulation method to quantify the impact of various PWM schemes on the current ripple. Finally, both the reliability and the lifetime of DC-link capacitor are discussed based the spectrum of DC-link capacitor current.