用2812实现三相SPWM驱动波形，所实现的SPWM波形载波频率为3kHz,载波比N=60，调制度为0.8，调试已通过可以使用。-By 2812 to achieve a three-phase SPWM driving waveforms implemented SPWM waveform carrier frequency of 3kHz, carrier ratio N = 60, modulation of 0.8, you can use the debugger has passed