Design On Auxiliary Inverter Of HXN3 Locomotive

The auxiliary inverter is an important part of auxiliary power supply system in the electric locomotive, and it is not only used to provide power for the auxiliary equipment, but its performance helps determine the operation of the locomotive. A research to the auxiliary inverter that drives the air compressor and cooling fan of the type HXN3 locomotive is proposed, and we can realize the localization of technology by replacing the original imported inverter with that presented in this paper.Firstly, according to the requirements of the auxiliary inverter, the project of hardware circuit is composed of the design of drive circuit, main control circuit, sampling circuit, protect circuit and the type of IGBT. This paper introduces the working principle of the hardware circuit in detail. Besides, the correspondence between sampling value and actual value and the trigger conditions for hardware protection are deduced.Secondly, this paper describes the principle and the implementation method of the SVPWM that is employed in the auxiliary inverter of type HXN3 locomotive. Based on the low voltage of the DC bus in the running process of locomotive, dual mode over modulation strategy of SVPWM is presented and elaborated, which improves the utilization of DC bus voltage.Thirdly, the output characteristic of inverter with the conventional modulation and dual mode over modulation strategies meets the requirements by simulation analysis and experimental results. Finally, the experiment of auxiliary inverter and loading alignment is carried out and the results indicate that the auxiliary inverter has an excellent performance and air compressor can be driven by inverter with order. Therefore, it’s proved that the auxiliary inverter can be a substitute for original imported inverter and the technical performance of inverter is up to standard.