Design Of Power Inverter For The Train Air-conditioning Of CRH2 EMU Based On STM32

When the quantity,the speed and the safety of railway trains meet the needs of people,people turn to put forward higher requirements for the comfort of railway trains.In order to make the ventilation system work properly,and ensure the health and the safety of the passengers,it’s really important for control system of train’s air-conditioner to have the optimization design.In this paper,we design a power inverter for the train air-conditioning of CRH2 EMU based on STM32.Unlike other train air-conditioning in China,CRH2 EMU trains use air-conditioning unit under the carriage with variable frequency control,which put forward higher requirements for the power inverter.In this paper,it firstly introduces the refrigeration system and the control system of the train’s air-conditioner to determine the power inverter’s role in the system of the train’s air-conditioner.At the same time,cooling mode of the train’s air-conditioner was introduced in this paper to provide the basis for the control mode and the parameters of the power inverter.Real-time temperature is compared to expect temperature by the main controller of the air-conditioning.Then the operation mode is set and control information such as start,stop and frequency are sent to power inverter by the main controller of the air-conditioning.According to the information sent by the main controller,the power inverter transforms the single-Phase AC into the suitable three-phase AC to make the fan and the compressor work well.In order to achieve this function,the single-Phase AC is transformed into the steady DC voltage by single-phase half-controlled rectifier bridge circuit and buck circuit.The steady DC is then transformed into the suitable three-phase AC by three-phase rectifier bridge circuit.And the V/F control principle and three harmonic injection method are applied to realize the control of the variable frequency and improve the DC BUS voltage utilization.According to the demand,the hardware design of the power inverter is divided into the rectifier step-down circuit unit,inverter unit and control unit.The control program of the power inverter is composed of main program,interrupt program,communication program and so on.In addition to the realization of the basic control function,the power inverter can observe the run status and give feedback.After completing the selection of main circuit topology and control mode,the design of hardware and software,the experimental platform was built.By comparing the simulation results and experimental results,it shows that the performance of the power inverter meets the demand and which is appropriate for the train air-conditioning of CRH2 EMU.