Implementation and Analysis of Low Stress PWM DC-DC Converter for Battery Charger

Objective: A highly efficient battery charger is designed using high frequency complementary pulse width modulation. This paper develops a novel soft switching approach to improve the efficiency of the circuit. Methods: The analysis of the newly developed converter is done to develop the mathematical equations. These equations are used to design the converter parameters. In order to reduce the switching losses of the switches during the on and off period, zero voltage switching is employed. All control functions are implemented in microcontroller with a single chip to vary the pulse width of the gate pulses based on the output voltage feedback from the charger unit. Findings: This charger circuit does not increase the conduction losses to reduce the switching losses. Complementary pulse width modulation used to reduce the switching losses which results in wide range of soft switching operation. Zero voltage switching is achieved at all load conditions. Rectifier diodes in the output do not suffer any reverse recovery losses. The proper selection of modes of operation of the circuit helps in reducing the circulating current. Since the circulating current in the primary circuit is eliminated, extra snubber circuit is eliminated from the circuit. The developed battery charger has a simple structure, low cost, easy control and high efficiency. The maximum efficiency is found to be 96%. Conclusion: Simulation and experimental test results of the proposed battery charger shows better efficiency with reduced losses over the traditional pulse width modulation converter.