A Carrier-Based Unbalanced PWM Method for Four-Leg Voltage Source Inverter Fed Unsymmetrical Two-Phase Induction Motor

This paper presents a carrier-based unbalanced pulsewidth-modulated method for a two-phase four-leg voltage source inverter (VSI) and its realization for an unsymmetrical two-phase induction motor. A modulation strategy is developed to synthesize unbalanced two-phase output voltage waveforms based on the unipolar modulation technique with open-loop V/f control. The proposed control scheme allows independent magnitude controllability and quadrature phase angle for unbalanced two-phase output voltages. Thus, the modulation algorithm makes the four-leg VSI inequitable with unbalanced two-phase loads. Simulation and experimental results confirm the feasibility of the control method for the inverter.