Scalar Approach Based PWM Strategy for Two-Level Three-Phase VSIs to Reduce Switching Losses and RMS Current in DC-Link Capacitors

This paper presents a novel pulse-width-modulation (PWM) strategy for two-level three-phase voltage source inverters to reduce both of the switching losses and the root-mean-square (RMS) value of DC-link capacitor current in all operating conditions. This objective is achieved by the zero-sequence signal injection method of optimal discontinuous PWM strategy having the minimum switching losses regardless of the power factor (PF) and the proper use of multi-carrier signals. It can be implemented easily with the generalized scalar approach. Also, the selection processes of zero-sequence signal and carrier signals are carried out by using the information of instantaneous phase currents, so the PF calculation is unnecessary. The performance of proposed PWM strategy is theoretically analyzed. Furthermore, simulation and experimental results are provided to verify the effectiveness of proposed PWM strategy.