Performance Evaluation of Multi-Modulation Single-Carrier PWM Methods for Motor Drive Applications

What is it about?

Due to their numerous benefits, multi-modulation single-carrier pulse width modulation (MSC-PWM) approaches are becoming more prevalent in multilevel converter topology control systems. Compared to traditional multi-carrier PWM techniques, MSC-PWM methods present more straightforward real-time implementation, while achieving acceptable harmonic performances. However, their application remains limited to grid integration of photovoltaic converter systems, and no literature examines their suitability and effectiveness in multilevel converters supplying electrical machines. This paper uses the traditional and modified MSC-PWM methods to discuss the design and implementation of vector control for an induction motor fed by a multilevel cascaded H-bridge inverter. First, the vector control scheme is briefly introduced, and then each MSC-PWM method’s implementation scheme is thoroughly described. Then, the effectiveness of the investigated MSC-PWM methods is evaluated through steady-state and dynamic computer simulation results. Finally, a performance comparison of different PWM methods is conducted based on the spectra and THDs of the motor voltage, current, and electromagnetic torque. According to the comparison study, the modified MSC-PWM technique is superior to the conventional MSC-PWM method in reducing the motor voltage THD by up to 30%, motor current THD by up to 40%, and subsequently reducing the torque ripple in the motor air gap.

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Why is it important?

This paper extends and generalizes the implementation of the MSC-PWM and the Multi-Modulation Single-Carrier PWM methods for a field-oriented control of a cascaded H-bridge multilevel inverter supplying an induction motor.

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