A comparative analysis of different pulse width modulation methods for low cost induction motor drives

Many pulse width modulation (PWM) methods for low cost induction motor (IM) drives have been proposed to design high performance industrial motor drives. However most of them have unbalance three phase output currents due to the dynamic unbalance between the two capacitors. Three different PWM methods, namely; hysteresis current control, sinusoidal pulse width modulation (SPWM) and a novel four switch low cost IM drives are discussed in this paper. The second one, namely SPWM, is based on the generalization of existing methods, and the third one is the proposed method, which is an improvement over the two other methods. Although all three schemes can provide three output currents with 120° phase shift for IM drive, the proposed technique is superior to others in achieving more precise current control with minimum distortion and harmonic noise, and at the same time, negligible unbalance in output currents. Simulation and experimental results of hysteresis current control, SPWM method and new proposed method is presented in order to confirm the effectiveness of proposed method in providing balanced three phase output currents and voltages.