Solutions and experimental verification of bipolar selected harmonics elimination PWM waveforms Applied in control system of induction machine

Selected harmonics elimination PWM (SHEPWM) strategy adopted in railway driving system promises to have better performance than other PWM strategies, such as SVPWM and SPWM. However, since SHEPWM was proposed, the calculation of switching-angle curves has been a hot research point. Up to now, many approaches have been applied and multiple solutions of SHE equations have been obtained. This paper presents a combinational approach based on mathematical software toolboxes, which is fast and convenient for engineering applications. Detailed explanation of calculating switching-angle curves is listed. Another undocumented set of switching-angle curves for N=4 is shown to confirm the proposed approach´s effectiveness. Finally, certain switching-angle curves below 60 are picked for simulation and experiments, which are both based on closed-loop vector control system of induction machines. Results prove that harmonics selected are eliminated effectively.