A novel technique for reducing leakage current by application of zero-sequence voltage

This paper proposes a technique for reducing the leakage current flowing into a power source as a conductive noise. This leakage current may have an adverse effect on the peripheral equipment, e.g., causing malfunctions. The proposed technique requires us to add a zero-sequence voltage to the output voltage reference of the inverter. The zero-sequence voltage can be controlled without affecting the driving characteristics of the motor. In a motor drive range, a counter EMF increases with an increase in the motor speed. The proposed technique, therefore, controls the zero-sequence voltage as a function of the inverter output frequency; as a result, a stable motor drive and reduction in the common-mode current are realized simultaneously. Simulation and experimental results prove the validity of the proposed technique.