High Performance Speed Control For Three-Phase Switched-Capacitor Multilevel Inverter Fed Induction Motor Drive

This paper investigates the speed control of a three phase switched-capacitor multilevel inverter (TSCMLI)-fed induction motor (IM) drive in order to enhance its performance. A multilevel inverter generates stepped sinusoidal waveforms of lower harmonics with increasing levels. The TSCMLI of 7- level line voltages synthesized using phase-disposition pulse width modulation (PD-PWM). The multi-level inverter output with the least THD is fed to the induction motor, and its speed is regulated by controlling the slip speed and maintaining constant V/f. A PI controller is implemented to ensure that the motor speed remains at its reference level. The performance of the closed loop scheme is evaluated with various reference speeds, dynamic load, and speed disturbances. Comparative evaluation of the performance characteristics and system efficiency of a closed loop TSCMLI and v/f fed induction motor drive is presented. Finally, the validity of the results is confirmed using MATLAB/SIMULINK as an effective simulation tool.