Modular Charging Power Supply Based On Phase-Shifted Full Bridge DC-DC Converter

As rail vehicle transportation equipment, Electric locomotive has been widelyused in many industries. In recent years in the mining industry, as productionsecurity needs, the replacement of trolley locomotive by battery locomotive hasbecome a hot technological transformation, and the charger is necessary to configurethe battery locomotive. Currently, the charger which is mainly used is controlledrectifier charger; It has large volume, high harmonic content, low power factor. Toovercome these shortcomings, the development of high-performance charger whichis based on high-frequency switching technology is essential.Mining electric locomotive charger operating voltage is660V three-phasevoltage and it is prone to explode, so the charger must be completely sealed, and gasisolated. This put forward new demands for the charger: not only to meethigh-voltage standards, but also to meet the requirements of high efficiency. Tosolve this problem multiple DC/DC converter modules which have series input andparallel output structure is introduced. To improve its efficiency, the articlecompares and analyses a variety of DC/DC converter topologies. And finallychooses an efficient phase shift control full-bridge PWM soft-switching convertercircuit which has auxiliary inductor and clamping diodes. Through calculation andsimulation designs main circuit.In order to ensure the input voltage of each module is equal. Equalizingfeedforward circuit is introduced. Design the Equalizing feedforward control circuitwhich includes two control methods: one is based on PI ring the other is based onMCU, and compares the two control methods. To achieve constant output circuit andlimited out pressure characteristics, designs independent current loop and commonvoltage loop. through analyzing the amplitude-frequency and phase-frequencycharacteristics of the control circuit, design the PI parameters.In order to achieve intelligent control, use PIC to control the output current andoutput voltage to achieve the three-stage charging.Develop a two rechargeable power unit, carried out laboratory tests. Theexperimental results showed that: the input voltage between converter monomerscan achieve the equalizing; full load efficiency of not less than96%, conducive tothe sealed condition; Output voltage and output current fluctuations is not more than10%, in line with the charger on the relevant requirements.