Design and Implementation of Isolated Multi-Output DC-DC Power Supply with Fixed and Programmable Voltage Levels

Currently, most of the day-to-day electrical and electronic appliances require DC inputs of different voltage levels. Therefore, to use them in a DC micro-grid, DC-DC converters with multiple voltage levels are required. Standardization in DC micro-grid is not yet done. Hence, every micro-grid has to use specially designed converters. Switched mode power supplies, now-a-days, are having high efficiency (70- 80%), small size and light weight. Hence, these switching regulators are replacing the conventional linear regulators in many applications. In early days, the control circuitry is made up of discrete transistor stages or controlling the duty cycle of switching transistors. Now, control circuitry consisting integrated circuit and microcontrollers. This paper presents the design of isolated multi-output DC-DC power supply where input is taken from batteries or ultra-capacitors. Multiple voltage levels are obtained by designing the multi-winding transformer and further converting them into DC. Fixed output voltage levels are obtained as 5 V and 20 V, while programmable output voltage level is designed (50 V-140 V) by using DC-DC boost converter controlled with PI controller. This power supply is designed and simulated in MATLAB Simulink.