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Efficiency Improvement of Feed Forward Controlled Buck Converter by Passive Auxiliary Circuit

Eldhose Kurian, Sija Gopinathan, Neetha John

Generally Buck Converter circuits have snubber circuit where switching losses are dissipated in external passive resistors; this is known as hard switching. Here a new passive auxiliary circuit topology is introduced so that the generation of switching losses are avoided by forcing voltage (ZVS) or current (ZCS) to zero during switching. The efficiency is thus improved due to reduction in switching losses. The operation principles and detailed steady state analysis of the ZVT-PWM synchronous converter with a passive auxiliary circuit are presented. Also, Feedforward control is accomplished by sampling the converter input voltage (instead of the output voltage, as in negative feedback control) and using this signal to control the duty cycle, to regulate the output voltage against line voltage variations (line disturbance).