Active clamp PWM forward converter with self driven synchronous rectification

The necessity of developing high efficiency and high power density on board DC/DC power converters with low output voltage for telecommunication applications leads to substitution of the rectifier diodes of the output stage by synchronous rectifiers. Control complexity and driving losses are the main constraints of this technique. A very simple implementation of self driven synchronous rectification in the active clamp PWM forward power converter is proposed. The absence of control circuitry and the minimization of losses are the main benefits of this circuit, whose analysis and optimization are addressed. Very high overall efficiency (89%) has been obtained in an actual prototype (3.3 V, 20 A)