Performance analysis of an induction motor drive powered by a cascaded H-bridge multilevel inverter

This paper proposes an improved pulse width modulation (PWM) strategy based on a modified reference signal for a 5-level cascaded H-bridge multilevel inverter (CHB-MLI) fed induction motor (IM) drive. Designed for applications such as submersible pumps, flour mills, compressors, lathes, and other industrial machinery, the approach addresses the growing demand for efficient and reliable motor control systems. Although multilevel inverters are well-suited for low-voltage IM applications, their performance is highly dependent on the PWM scheme. Conventional strategies often result in higher harmonic distortion, torque ripple, and power losses. To mitigate these issues, a novel 13th Harmonic Injected Trapezoidal PWM (THITRPWM) technique is introduced, combining a trapezoidal waveform with a 13th harmonic signal to reduce lower-order harmonics (3rd and 5th), THD, and torque ripple, thereby enhancing drive efficiency. Simulation results in MATLAB/Simulink demonstrate that this level-shifted PWM approach produces a smoother motor response and higher-quality output waveform than traditional methods. Furthermore, a comparative study of electrical, thermal, and driver stress for 5-level, 7-level, and 9-level CHB-MLIs is presented. The research also examines stress behavior and gate driver requirements in H-bridge modules, providing insights into practical implementation challenges in multilevel inverter systems. In addition, a Low Voltage Ride Through (LVRT) feasibility study is conducted for 5-level CHB-MLI systems, highlighting their potential reliability under grid voltage disturbances. These findings contribute to advancing robust and efficient CHB-MLI-based IM drive solutions for industrial and commercial use.