A low-loss high-power-factor flyback rectifier suitable for smart power integration

A low-loss, high-power-factor flyback rectifier is presented, which is designed as a possible application for a new type of smart power integrated circuit. This is going to be manufactured by ST Microelectronics using the VIPower^(c) M3 technology and will include on the same silicon chip both control circuitry and an emitter switching power device. In order to avoid dangerous interactions between power and control part of the integrated circuit, it is necessary to control the rate of change of the power device voltage at turn off. Accordingly, a lossless passive snubber was added to the conventional converter topology. The snubber also limits the voltage spikes across the power device, due to the transformer leakage inductance, and reduces the electromagnetic noise generation. A modified nonlinear carrier control is considered which, thanks to the integration of the switch current signal, ensures high power factor and inherent noise immunity together with a simple control implementation (no need of input voltage sensing, multiplier and current error amplifier). A 200 W converter prototype was tested in order to evaluate the achievable performance