Voltage-Injected PWM Variants for a Dual Two-Level Inverter-Fed Open-End Winding Induction Motor Drive

In this article, three new pulsewidth modulation (PWM) methods are proposed for a dual-inverter-fed open-end winding induction motor (OEWIM) drive aimed at reducing voltage harmonic distortions in the inverter output. The proposed PWM variants are devised using appropriate voltage injection to the modulating signals. The proffered PWM variants for the dual inverter are analyzed through rigorous harmonic analysis to arrive at complete harmonic description using double Fourier integral approach (DFIA) to obtain their characteristics. For all the PWM variants, optimal values of voltage injection are also obtained, which yields lower voltage harmonics at the output of the dual inverter. The analytical solutions thus obtained are verified through simulations and experimental results, and the improved harmonic performance compared to the existing PWM techniques is also presented. Identifying the shortcoming of reduced limits of linear modulation of the proposed PWM techniques, a solution to smoothly slide-over to the phase-disposed PWM techniques is also demonstrated. Besides, the impact of the proposed PWM variants on improved motor current ripple and torque ripple performance when used with field-oriented control is presented and compared with some existing PWM methods to showcase their superior performance characteristics and also the usefulness of the envisaged PWM methods.