Design and Implementation of Compact and Isolated Low Voltage High Current DC Power Supply using Synchronous Rectifier

Abstract

With advances in modern power electronics, Low-Voltage High-Current DC power supply is used extensively in industrial applications like arc furnace, fusion technology, arc welding etc. In conventional dissipative techniques, it has many disadvantages like lower efficiency, higher weight and size. The main aim of this project is to meet industrial needs like isolation between source and load, minimize the switching loss, high conversion efficiency, lower distortion in output voltage, current and also reduces the power supply package size using high frequency converters. Di fferent Isolated Converter topologies such as Forward Converter, Flyback Converter, Push-Pull Converter, Half-Bridge Converter and Full-Bridge Converter, among all these topologies Phase Shifted Full-Bridge topology has been selected in order to achieve the High Power applications. In this topology PWM techniques are used for power switches, so that they are going to switch at high frequencies which results in the reduction of the size of transformer, weight and cost of the overall power supply. At a lower switching frequencies and without use of Quasi Resonant Converter, the switching losses (turn on and turn o losses) are significant part of the power losses, which reduces the efficiency and increase the size of overall Power Supply. An attractive alternative method to reduce the switching losses and improve the effciency is that to replace the hard switching by soft switching in which zero voltage/zero current switching is used. In Low-Voltage applications, conduction loss of the diode bridge rectifier contributes signicant power losses in the Power Supply compared to the synchronous rectier. Feed forward technique has been adapted to minimize the output ripple from the DC link. The simulation of whole system was done in PSIM software and along with DLL block. After examining the simulation results the whole scheme implemented in hardware. The simulation of 900 W and 15 kW DC Power Supply was carried out and hardware of 900 W Prototype DC Power Supply was implemented. The 15 kW High Frequency Transformer is designed and prepared.