Minimization of switching frequency using dynamic sector detection for a three-phase four-leg VSI topology to compensate nonlinear load under unbalanced and distorted supply voltages

This paper presents a dynamic hysteresis current control for a three-phase four-leg voltage source inverter topology. In order to improve the performance and life of the power switches of voltage source inverter, we require an optimized control technique which reduces its switching frequency. Proposed hysteresis current control method is a generalized control method which minimizes switching operations to compensate nonlinear load under both balanced and unbalanced supply voltages. It is shown that this control scheme is able to reduce the switching frequency by more than 50% compared to conventional hysteresis current control method and retain the quality of load compensation. The effectiveness of the proposed control scheme is illustrated through simulations using PSCAD 4.2.1.