Optimum reduction of switching losses based on the two-phase PWM modulation method for two-level inverter

This paper proposes an optimum PWM method which reduces switching losses of an inverter most effectively by the two-phase modulation method. It selects the optimum one which minimizes a new switching (SW) loss estimation based on reduction effects in switching times considering phase currents among multiple reduction patterns. The proposed method was experimentally verified to select a optimal switching pattern which reduces its SW loss most effectively according to the on-line loss estimation by a DSP-based digital control system. The proposed method made it possible to reduce number of switching times of the largest or secondly largest current phase to 2/3 times. And it can automatically adapt to load conditions with various power factors. Measured switch losses are reduced to about 50-60% by the proposed method.