Modulation Strategies to Reduce DC Capacitor Current in Two-Motor Drive Systems

Abstract

This paper proposes a modulation strategy for a two-motor drive system that shares a battery and drives two main motors at variable speeds. Two-motor drive systems are required to reduce the DC link capacitor current to reduce system size and extend system life. The proposed method reduces the current of the DC link capacitor by outputting an appropriate combination of voltage vectors at the two inverters to offset the current of the DC link ripple. The effectiveness of the proposed method is demonstrated using experimental results of two inverters with the same and different output conditions. Compared with the interleave method, the proposed method reduced the root-mean-square (RMS) value of the DC link capacitor current by up to 50.4% when the output conditions of the two inverters were the same and 50.3% when the output conditions were different. Therefore, the proposed method can effectively reduce the current flowing in the DC link capacitor of a two-motor drive system.