PWM AC controller includes single-phase PWM AC controller and three-phase PWM AC controller, as an electrical AC voltage-regulating controller, it adopts DSP (Digital Signal Processing, called as DSP for short) and CPLD (Complex Programmable Logic Device, called as CPLD for short) as the control core, IGBT as the power control device and realizes adjustable output voltage magnitude by PWM control mode and its voltage waveform is sine wave. Its output voltage characteristics are similar to an auto-coupling contact-type voltage regulator. Because its power factor is higher than 0.98 and the total harmonic distortion of current THDI is less than 6%, the conversion efficiency of the power supply is more than 0.98. Under the condition that no any power factor compensation and harmonic wave absorption apparatus is attached, the power factor and harmonic wave have met the standard requirements of the State Grid.