Simple PWM approach for modulation of three-leg inverters driving two-phase symmetrical and asymmetrical machines

This paper presents a simple PWM approach for modulation of three-leg inverters driving two-phase induction machines. The main contribution of this paper is the development of a simple PWM modulation method to generate symmetrical and asymmetrical voltages suitable to fed two-phase induction machines. It is demonstrated that the amplitudes of line voltages can to vary from zero until 0.707 pu of DC-link voltage for symmetrical voltages, while one of the voltages can overcome 0.707 pu of DC-link voltage in the asymmetrical case. The results obtained with the proposed modulation technique are similar to those obtained with space vector modulation, however, the implementation of the proposed modulation technique is much more simple than the implementation of space vector modulation. Experimental results that validate the theoretical analysis are presented and they demonstrate the good performance and simplicity of the proposed modulation method.