A DIRECT DIGITAL-CONTROL FOR THE PHASE-CONTROLLED RECTIFIER

Abstract

A direct digital control of the phase-controlled rectifier (PCR) is implemented with a minimal control hardware structure. A novel digital phase-locked voltage control (PLVC) without detecting the line voltage is presented. An inner fast control loop is proposed to stabilize the PCR system and to obtain its constant loop gain. In the inner loop, an averaging function is introduced to feedback the average dc voltage of the PCR output without the feedback filter. Its synchronism is modeled and analyzed. An optimal constant digital integral, proportional, and measurable variable feedback (IPM) current controller with a time-multiplied performance index is also proposed to obtain a good dynamic response of the output current. All control functions are implemented with an Intel 8797 single-chip microcomputer. Experimental results show that the proposed scheme gives good dynamic and static performance for the PCR system.