Modeling of high-power-factor rectifiers based on switching converters with nonlinear-carrier control

The paper presents a unified modeling and analysis of high-power-factor rectifiers based on switching converters with nonlinear-carrier control (NLC). In NLC control, which offers simple, high-performance power-factor correction (PFC), the switch duty ratio is obtained by comparing a signal derived from the switch current with a periodic nonlinear carrier. A general expression is derived for the required nonlinear carrier waveshape with any PWM switching converter. A unified sampled-data model is used to demonstrate stability of the current loop under all operating conditions. A continuous-time, switching-frequency averaged model is derived to determine the bandwidth of the current loop, and facilitate the input filter design. A line-frequency averaged model is presented for the purpose of designing the output filter and the voltage-regulating loop. Experimental verification results are described for a 150 W flyback rectifier.