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[摘要]
对于交流调速系统中脉宽调制(PWM)过程同时应用空间矢量脉宽调制(SVPWM)和特定谐波消除脉宽调制(SHEPWM),低频时采用SVPWM,中频时采用SHEPWM。这种混合调制方法避免低频时SHEPWM计算存储量较大和中频时SVPWM谐波特性变差等问题。采用一种谐波电流过零点切换方法,实现了SHEPWM中开关角个数由5~1逐步切换过程的平滑过渡;在与SVPWM的切换过程中,采用参考电压矢量同相切换方法,实现了混合调制之间的平滑过渡。仿真结果验证了理论的正确性。
[Key word]
[Abstract]
Space vector pulse width modulation (SVPWM) and selected harmonic elimination PWM (SHEPWM) are applied simultaneously in the PWM process of AC speed regulation system. SVPWM is adopted at low frequency and SHEPWM is used at medium frequency. This hybrid modulation method avoids the problems of large storage of SHEPWM at low frequency and variation of SVPWM harmonic characteristics at medium frequency. A zerocrossing point switching method is proposed for harmonic current switching, which guarantees the smooth transition of switching angle number from 5 to 1 in SHEPWM technology. In the switching process from SHEPWM to SVPWM, a reference voltage vector inphase switching method is adopted to achieve smooth transition. Simulation results prove the validity of the theory.
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