Effect of a CMV elimination PWM on stator current ripple in a dual two-level inverter fed induction motor drive

Dual two-level inverter employing an open-end winding induction motor (OEWIM) drive can synthesize three-level voltage space phasor. PWM switching methods for the dual two-level inverter are presented in this paper that offer dual advantage of eliminating the common mode voltage (CMV) in the dual-inverter scheme and also limiting the switching power loss of the dual-inverter to one inverter only at all instants of time. The instantaneous error voltage in stationary reference frame is identified from the switching states of the dual-inverter and thereafter current ripple in stationary reference frame is predicted with the use of proposed PWM methods. Analytical expressions are also developed to quantize the RMS value of current ripple in the motor phase current. The performance of the proposed PWM methods and the current prediction is examined from simulation studies and verified experimentally.