A Novel SVPWM Control Strategy for Dual Inverter System to Eliminate Common Mode Voltage with High Modulation

Abstract

In this paper, a novel SVPWM scheme to suppress common mode voltage for open-end winding induction motor (OEW-induction motor) drive is presented. Compared to other general three-level inverter configurations, the control strategy of this dual two-level inverter structure is more flexible. But with a single dc power supply in the OEW-induction motor drive system, many negative effects will be brought due to the presence of common mode voltage, such as causing circulating current in the winding and reducing system reliability. Owing to elimination the negative effect of the common mode voltage, one way is to synthesize the reference voltage with the switching combinations which do not produce common model voltage. However, the maximum modulation will greatly be reduced with these switching combinations being used. In order to maintain the maximum modulation while the common mode voltage is suppressed, a novel SVPWM scheme for this structure has been proposed. It is illustrated that the average of common mode voltage of the system is suppressed in each sampling-time interval by adjusting the placement of voltage space vectors and reasonable voltage selection. In addition the switching frequency of this novel control strategy for dual two-level inverter system is equal to the traditional SVPWM control strategy, and it has a significant improvement of the maximum linear modulation index. The proposed modulation control strategy has been verified by the simulation on a MATLAB platform.