Digital Controller for Active Clamp based Synchronous Forward Converter for High Power Applications

Abstract

The Digital technology playing vital role in power electronic industry by providing novel method to control the DC-DC converter. In this project closed loop control of the converter is built by using reprogrammable FPGA A3P250- VQ100. This FPGA is programmed to develop the four MOSFET gate pulses with required delay, to drive the Main MOSFET, Active clamp MOSFET circuit and secondary side synchronous MOSFETs. Active clamp reset technique is used to reset the Transformer core, which helps to operate the converter for wide input voltage range and to reduce the Voltage spikes across the Main MOSFET. This circuit allow the main MOSFET to turn on at zero voltage, which reduces its switching loss and helps in improving the overall efficiency of the converter. Due to the low forward voltage drop, the MOSFETs are used as rectifier in the secondary side of Forward topology. Isolated Magnetic Feedback generator is used to sense the output voltage. The 12 bit ADC is used to convert the feedback voltage from Analog to Digital. In this paper, concentrating on designing 150W DC-DC converter by using the Digital control technique. The realization of Digital PID algorithm and over current, input raw under voltage and over voltage protection is discussed.