Design and implementation of quad-output flyback converter for space applications

This work is focused on design, analysis and implementation of current mode controlled, quad-output flyback converter. The design of proposed converter illustrates the achievement of tight line, load and cross regulation by using post regulators. The proposed converter is operated at a switching frequency of 100 KHz. The UC1846 PWM controller is used which has features of pulse by pulse current limiting and soft start capability and under voltage lockout with current mode control technique. A separate bias winding is used for converter loop feedback and also start-up circuit is used to enhance soft start in converter. Primary side current mode control scheme is achieved by comparing input inductor current with bias winding output to modulate the width of pulses generated from PWM controller. The proposed converter is implemented on a hardware prototype with a quad-output using the input voltage range from 65-75V with an efficiency greater than 50%. This converter has protection circuits such as under voltage protection as well as over current protection and current fold back circuit and inbuilt EMI filters.