Analysis of the Two-Switch Forward Converter with Synchronous Current Doubler Rectifier

A soft switching two-switch forward converter is presented to achieve zero voltage switching turn-on of switching devices. In the adopted converter, a buck-boost type of active clamp is connected in parallel with the primary winding of transformer. The energy stored in the transformer leakage inductance and magnetizing inductance can be recovered so that the peak voltage stress of switching devices is limited. The resonance between the transient interval of two main and auxiliary switches is used to achieve ZVS turn-on of all switches. The current doubler synchronous rectifier is used in the secondary side of transformer to reduce the root mean square value of output inductor current, transformer secondary winding current and output voltage ripple by cancelling the current ripple of two output inductors. First the circuit configuration and principles of operation are analyzed in detail. The steady state analysis and design consideration are also presented. Finally, experimental results with a laboratory prototype based on a 380 V input and 12 V/30 A output were provided to verify the effectiveness of the proposed converter.