Dodecagonal Voltage Space Vector-Based Hybrid PWM Technique for the Reduction of Torque Ripple in OEWIM Drive

The dodecagonal voltage space vector PWM (DSVPWM) applied to the open-ended winding induction motor (OEWIM) using the switched capacitor filter (SCF) topology has the benefit of effectively suppressing phase voltage harmonics of the order of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{6 n}\;\pm\; 1$</tex-math></inline-formula> (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> is an odd number) in the entire modulation range. The DSVPWM exhibits superior harmonic performance compared to the CSVPWM in the complete speed range. However, the torque ripple performance is in the linear modulation range, almost comparable to the CSVPWM, and it exhibits superior performance at higher speeds. This research article focuses on the further improvement of the torque ripple on the OEWIM, compared to the DSVPWM, by employing a hybrid PWM switching sequence. This hybrid PWM sequence is a combined sequence of the DSVPWM sequence and advanced bus clamping sequences. Analytical, simulation, and experimental studies demonstrate that the hybrid PWM exhibits equivalent RMS torque ripple performance to DSVPWM at low and medium speed ranges. However, it significantly improves at a higher speed range, with a marginal improvement in the current THD at higher speed ranges. A 2.2 KW OEWIM is employed in the experiment to verify the effectiveness of the suggested hybrid PWM approach.