Common-Mode Voltage Reduction and Fault-Tolerant Operation of Four-Leg CSI-Fed Motor Drives

This letter proposes a four-leg current-source inverter (CSI) fed three-phase motor drive. Different from the previous four-leg CSI inverter, the proposed configuration introduces the fourth leg in CSI, which connects to the neutral point of the motor through an extra output filter capacitor. Therefore, the proposed configuration can not only reduce the common-mode voltage (CMV) under the normal condition, but also provide the fault-tolerant operation ability under open-circuit faults in windings and switches. The dedicated space vector modulation (SVM) strategies have been designed. Compared with prior research on CMV reduction, the four-leg method has the full range of modulation index and will not increase any harmonics in the currents. Meanwhile, the fault-tolerant ability is offered, which can further enhance the reliability of the motor drive. A laboratory prototype has been built to experimentally verify the effectiveness of the proposed motor drive topology and the control schemes.