A reduced-switch dual-bridge inverter topology for the mitigation of bearing currents, EMI, and dc-link voltage variations

This paper presents a reduced-switch-count dual-bridge inverter approach fo r the mitigation of motor bearing currents and electromagnetic interference (EMI). The proposed inverter employs two four-switch inverters and is cont rolled to generate balanced excitation of dual-voltage-rating induction mot ors under pulsewidth modulated operation. The proposed approach eliminates the common-mode voltage and, thus, prevents the motors from premature beari ng failures in addition to reducing the conducted EMI Compared to the conve ntional four-switch inverters, the proposed inverter also eliminates the si ngle-phase circulating current and voltage variations across the dc-link ca pacitors, which allows smaller capacitance to maintain the dc-bus voltage. Theoretical analysis as well as simulation and experimental results are pre sented to verify this concept.