Research And Design Of Parallel Low-Voltage High-Current DC Power Supply

In terms of the means of transportation people take,the subway light rail high-speed train has been favored by more and more people.According to relevant data statistics,DC power supply mode is the main mode of metro traction power supply system in China.In this traction power supply system,the breaking element is extremely single,only low-voltage DC circuit breaker.The importance of this instrument in the process of power supply system protection and other equipment safety protection can be imagined.After the subway is put into use,in order to ensure the safe operation of the subway,the working performance of the low-voltage DC circuit breaker must be tested regularly,and the tripping test is usually used.The tripping test to detect the performance of the circuit breaker is mainly through the analysis of the tripping time.In the process of the experiment,a large current is added in a very short time,which is similar to the short circuit of rail transit.The capacity of power supply and the rising rate of output current are two important concerns in trip test.Through the analysis of the current development trend of power supply,a single module full bridge converter test prototype is developed,which is 5000A/5V.This test prototype is based on phase shifted full bridge converter and DSP28335 controller.The parameters are calculated in detail in the research process,and the device is completed Model selection,software design and hardware design.On the basis of single module experiment,parallel sub modules with the same structure are studied,in order to achieve the purpose of flexible capacity allocation through modular design.In order to solve the problem of unbalanced output current caused by the difference of external characteristics of DC power supply,two current sharing methods,namely three loop current sharing control strategy and fuzzy adaptive PID control algorithm,are proposed,and the two control methods are designed and analyzed in detail.Through comparative study,no matter the power supply is in full load,sudden load increase or sudden load decrease,the current sharing accuracy of parallel system using fuzzy adaptive PID control algorithm is higher than that of three loop control mode,which achieves the current sharing operation of the system and meets the requirements of the current sharing accuracy of this design.Experiments show that the prototype can meet the requirements of power supply for DC circuit breaker tripping test,which has important guiding significance for the design of DC circuit breaker tripping test power supply in rail transit industry.