Advanced 24-Sector Bus-Clamping PWM Techniques for Improved Performance of Split-Phase Induction Motor Drives

Advantages of a split-phase induction motor (SPIM), such as reduced torque pulsations, lower voltage rated power converters, higher torque per ampere and increased reliability, make it suitable for high-power variable-speed applications. Two advanced bus-clamping pulse width modulation (ABCPWM) techniques are proposed in this article for SPIM drives to enhance their performance further. These techniques employ special switching sequences which apply the null vector once and one of the active vectors twice in each sub-cycle. Stator flux ripple-based analysis brings out the superior performance of the proposed special sequences over the conventional sequences at high modulation indexes. Switching loss factor-based analysis shows that the inverter switching loss gets significantly reduced with the proposed PWM techniques at high power factors. Simulations and experiments on an 8 hp, 200 V, and 50 Hz SPIM drive show that the total harmonic distortion (THD) of stator current is reduced significantly at high speeds by the proposed PWM techniques at the same average switching frequency. In particular, one of the proposed techniques improves the no-load stator current THD by 32% at rated frequency, compared to a state-of-the-art space vector based PWM (SVPWM) technique.