Control of Switch-mode Power Supplies A digital approach for half-bridge converters

Abstract

In this master thesis a digital controller for a switch-mode power supply (SMPS) based on a half-bridge topology has been implemented. The SMPS originally has an analog control board. This original control board has been removed and replaced by a digital controller. Hardware for output voltage and current measurement was constructed as well as gate driving circuitry. Control design was performed based on an average model for the half-bridge. Two different controllers were designed where one regulates the output voltage and the other regulates the output current. The controllers have been implemented digitally using a STM32 microcontroller from STMicroelectronics. The developed digital controllers has been tested to investigate the performance of the system. The thesis work also contains theoretical studies on paralleled SMPS in system. Test results show that the SMPS, controlled by the digital controller, can deliver constant voltage and constant current. When combining the two modes, a voltage source with current limiting or a current source with voltage limiting is obtained. However, the noisy environment due to the switching signals makes measurements questionable and further investigations of the performance of the controllers should be done.