| High speed railway is developing fast in China these years. It has been highly accepted by the people that to going out by taking high speed railway. With the disadvantages such as highly depending on catenary, single power supply mode and the harmonic pollution when regenerative braking, the high speed electric multiple units (EMU) still need improvement. Relying on the key project of National Eleventh Five-Year Plan National Science and technology support program, research on the key technology of hybrid EMU and development of the prototype vehicle, in order to realize that the hybrid EMU can work in place where there is no catenary, this paper designed a LiFePO4battery energy storage system and developed some proper control strategy, eventually achieved making the hybrid EMU traction converter which can meet the design index.Firstly, according to the operation curve and traction characteristic, the maximum power and energy demand for the energy storage system is worked out. With comparison of some often used energy storage element, the LiFePO4battery is chosen as the energy storage storage element. The LiFePO4battery is packed according to the technical index of energy storage system. The charge and discharge characteristic of the LiFePO4is studied to help develop the control strategy.Secondly, the design demand of the energy storage system main circuit is analyzed and the bi-directional buck/boost DC/DC converter is choosed as the main circuit topology of the energy storage system. The key parameter of the main circuit is confirmed and the therminal simulation is processed. The control system with the core of DSP-FPGA is designed.Thirdly, the control strategy of charge control of the LiFePO4battery, the power supply mode of the energy storage system and switch of the operation mode of the energy storage system is researched in this paper. The single current close loop control is chosen when the battery is charged. And the dual close loop with the voltage outter loop and the current inner loop is chosen when the energy storage system is working as the main power of the traction system. A simulation model is set in MATLAB to evaluate the control strategy.Eventually, some experiment and test, containing battery charge experiment in high charge rate and low charge rate, coordination with the traction power supply system when passing neutral section and full power back-to-back motor experiment, are done in the experimental platform based on the hybrid traction converter. The results of the experiment proved that the energy storage system can completely meet the design demand. |
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