Light load stability improvement for single-phase boost PFC rectifier using input current self-control technique

This work presents a stability evaluation for a single-phase boost PFC converter employing digitally implemented input current self-control to achieve close to unity power factor. Both analog and digital approaches for the proportional compensator are studied and the effects of transport delays found in digital controllers are considered. It is verified that the use of a digital proportional controller may lead to system instabilities at light loading conditions. The replacement of the proportional compensator with an adaptive lag compensator is proposed. This sensibly improves light load stability, while being straightforward to implement. Additional stability margin is achieved by combining the adaptive lag compensator with a linear predictor filter. Experimental verification is presented based on a 500W lab-prototype.