Instantaneous value control using a synchronous-integrating filter for PWM AC voltage regulator

Instantaneous value control using a synchronous-integrating filter and a digital signal processor (DSP) for the PWM (pulse-width modulation) AC voltage regulator is presented. The proposed system has a quick response, thus achieving the performance of the high-speed AC chopper using power MOSFETs. A novel type of filter, a synchronous-integrating filter, completely eliminates the ripples in the output voltage caused by PWM chopping operation. The sampling values of the filter output are considered to be the instantaneous values of the fundamental component included in the output voltage. A high-speed DSP instantaneously computes the pulse width at each chopping cycle. The dead time is to be considered in the control algorithm. Experimental results show that the proposed system has a quick transient response, within a few hundred microseconds. Moreover, it is possible to reduce the low-order harmonic distortion