Design And Realization Of Medium Frequency Switched Mode Power Supply

Medium frequency power supply is widely used in aircraft, communication, metal smelting, electrostatic precipitator which require high quality of power. Conventional 50Hz thyristor based power supply suffers some drawbacks, such as insufficient power factor, large volume, large weight, high voltage ripple of the precipitator voltage, low average value of the voltage, slow recovery after flashing, single output waveform. While the structure and control strategy of high frequency switched mode power supply are more complicated. There is more conducted electromagnetic interference of high frequency transformer. The IGBT medium frequency power supply improves the frequency of the output voltage relative to 50Hz, solves the problems above. And medium frequency power supply also provides an advantage of easy reform from conventional 50Hz power supply. It is a high performance and high reliability power supply for ESP. So a medium frequency power supply based on DSP for ESP is studied and designed in this paper.In this paper, the topology of main power circuit and the pre-charge method of 3-phase mains input rectifier are studied. The power electronic components in the main power circuit are chosen from calculation. The power structure of the control circuits and signal conditioning circuits are designed. And the minimum system and peripheral circuit of DSP are designed. IGBT driver circuit is also designed. An over-current protection circuit based on FPGA and a temperature measurement circuit is designed to improve the reliability of the power supply. In aspect of software, two kinds of SPWM modulation methods are realized and compared with simulation. The method of flashing detection and flashing control algorithm are studied. And the communication of Modbus protocol is realized.