DSP based digital controller for high voltage SMPS

Abstract

This work is on Digital Signal Processor (DSP) based digital controller for 2 kW switch mode power supply (SMPS)". The SMPS is based on `LLC type resonant converter'. The SMPS will be used for a DC power source for biasing CW Ion-Source. The Ion-Source requires DC source variable from 10 kV to 20 kV with maximum current rating of 100 mA. The DC source is used in CW Hydrogen Ion source to extract ions. The analog implementation of power controller comes with inherent disadvantage of aging, lack of flexibility etc. those are successfully overcomes by using digital based implementation. Also the choices of digital implementation platform being DSP give it a higher edge over a microcontroller. The main goal of this work is controlling the dc output voltage from 10kV to 20kV of the SMPS by using DSP (TMS320F28035) based digital controller. It has to generate variable frequency gate signals to the semiconductor devices (MOSFETs) used in half bridge configuration of SMPS. It also has to regulate the output DC voltage within ± 1% of set value in control loop. The LLC type resonant converter requires a variable frequency gate signal from 20 kHz to 30 kHz to vary the output DC voltage within specified range. These gate signals are generated by using DSP TMS320F28035 based Digital controller. The DC output of SMPS has been maintained within ± 1% of set value by PID control loop algorithm implemented in DSP. High frequency resonant converter is advantageous for various reasons. Increase in frequency reduces the size of magnetic components, compact light weight; soft switching reduces losses and less EMI generation. The DSP based digital controller has been developed and tested on experimental setup of 2 kW SMPS.