A characteristic analysis of four-leg inverter in two AC motor drives with independent vector control

This paper presents a characteristic analysis of a four-leg inverter. The four-leg inverter is a single inverter that can drive two alternating current (AC) motors independently. We show that an expanded two-arm modulation (ETAM) known as a modulation method of a five-leg inverter is applicable for the four- leg inverter and the two AC motors can be driven independently by this inverter with adapting the ETAM. We also show that a neutral point potential (NPP) of a capacitor bridge (CB) connecting w phases of two AC motors in common fluctuates. Moreover, we theoretically analyze about harmonic components of output voltage for four-leg inverter in using the ETAM