The Improvement Of 8K Type Electric Locomotive's Auxiliary Inverter System

The auxiliary inverter system of electric locomotive is used to cool down the main circuit and offer wind regime for the air brake system. Its normal working is critical for the stability and safe operation of the locomotives. The control panel of 8K type electric locomotive's auxiliary inverter system is composed of discrete device. This device is out of date, hard to maintain and has low operational efficiency. According to this, this paper provides some improvements of the auxiliary inverter system of 8K type electric locomotive.First, we improve the power supply circuit of the auxiliary inverter system. We replace the electric mechanical relay of the original circuit with solid state relay which is more advanced and has a high cost performance, and design the driver and protective circuit of the solid state relay.Secondary, we improve the power supply of the auxiliary inverter system. We integrate the control of inverter and rectifier in one DSP (Digital Signal Processor) control panel. Phase-controlled rectifier technique is adopted to control the rectifier. We introduce the principles of Phase-controlled rectifier briefly, compile corresponding software and show the results and waveform of our experiments. As for the control of the inverter, we supply two control strategies. Strategy 1: Keep the original control principles of the inverter unchanged. The inverter operates in 6-step voltage mode and starts up the same as the original mode. Strategy 2: Adopt SVPWM (Space Vector Pulse Width Modulation) technique to improve the operating principles of the inverter thoroughly. Firstly, the thesis analyzes the operating principles of traditional SVPWM control technique in detail. And the modulation wave functions are deduced. At the same time, to simplify the calculation, an optimized simpler method is used to realize the digital algorithm, and C programs are written.As for the hardware, the inverter module, protection module and control module based on the TMS320LF2407 are designed. This thesis project has finished the debugging of the system, and the result shows that hardware and software of the designed system is in reason.