An Approach to Compensate for Low frequency DC-Link Voltage Ripple in High Power ANPC Inverter

DC-link voltage ripple has an adverse impact on the performance of Electrical traction drives. Employing large DC-link capacitors may not be feasible in scenarios demanding high power density such as in Electric vehicle applications. This paper introduces a new technique to compensate for the DC-link voltage ripple in ANPC inverters employing a feedforward strategy. The proposed DC-link method is combined with hybrid space vector PWM (SVPWM) to effectively compensate for low frequency DC-link ripple as large as 20% by tracking voltage variation in real-time. The paper also includes derivation process for calculating the capacitor current in an ANPC inverter, which serves as the basis for selecting the appropriate capacitance value. Simulation and experiment results on a 14kW SiC ANPC inverter are presented to verify the effectiveness of the proposed technique, which successfully compensates for DC-link fluctuation.