SPWM是最常用的一种调制方法，SPWM信号是当改变正弦参考信号的幅值时，脉宽随之改变，从而改变了主回路输出电压的大小。当改变正弦参考信号的频率时，输出电压的频率即随之改变。-SPWM is one of the most commonly used modulation method, the SPWM signal is when the amplitude of the sinusoidal reference signal changes, the pulse width changes, thus changing the main circuit output voltage size. When the frequency of the sinusoidal reference signal is changed, the frequency of the output voltage is changed.