A Common Mode Voltage Reductions for Three Phase Coupled Inductor Inverter Using Multi-Carrier Interleaved PWM Strategies

Abstract

This work presents multi-carrier interleaved PWM strategies to control common mode voltage (CMV) in three phase coupled inductor inverter (CII). The proposed scheme has the feature of reduced number of switches with higher output voltage level. The major problem in the coupled inductor inverter (CII) topology is power loss in inductor that is related to the magnitude of current ripple in the winding. The proposed multi-carrier interleaved PWM technique is easy to implement when compared to other PWM techniques. The additional advantage is reduction of the current ripple in inductor. The minimization of current ripple in inductor winding leads to the reduction in the common mode current participation in the (Y-Δ) connected induction motor. The common mode voltage is represented as the integration of the common mode current in each phase. The multi-carrier interleaved PWM consists of the continuous and discontinuous modes of operation. By choosing the high effective switching state with the help of Discontinuous PWM technique for inductor winding, the common mode voltage (CMV) can be reduced without degrading the performance of the inverter. The proposed scheme is applied for three-phase coupled inductor inverter (CII) to obtain the five level output. The benefit of these proposed switching strategies is reduction of the common mode voltage in the range of +Vdc/12. The simulation with 1HP induction motor drive system is set-up in MATLAB and same result is validated effectively by hardware-FPGA SPARTAN-3E processor.