Modeling Simulation And Control Of EMU Three-Level Traction Converter

AC-DC-AC drive system is an important aspect in our railway commute drive. AC-DC-AC converter include four-quadrant rectifier link, DC link and three-phase inverter link. The principle of AC-DC-AC locomotive is that transformer transforms the high single-phase AC voltage from contact system to lower AC voltage first, then rectifier transforms this AC voltage to steady DC voltage, finally converter transforms this DC voltage to three-phase VFVV AC voltage as the voltage source for asynchronous motor.As we known, the theory basis of researching Electric Motive Units (EMU) three-level converter system is mathematical module. Therefore, in this paper it sets up the main circuit mathematic model of single-phase three-level rectifier, switch model of three-level inverter, model of asynchronous motor, mathematic model of three-phase asynchronous motor in static coordinate and synchronous rotation coordinate, unity mathematic model of three-level inverter and asynchronous motor. The establishment of mathematic model laid the foundation for the study of various control strategies and simulation based on this three-level topology. This paper analyses the basic principle of EMU three-level traction converter in detail. Instantaneous current control algorithm and SPWM algorithm are presented to single-phase four-quadrant rectifier, and for the three-level rectifier SPWM principle carried out a detail analysis. Space vector PWM control algorithm and balance control algorithm of neutral point voltage are presented to three-level inverterAt the end of this paper, with the application MATLAB/SIMULINK software, it has established the three-level converter system simulation model. It makes the simulation research on single-phase three-level rectifier simulation model and three-level inverter SVPWM simulation model, has obtained the simulation result and confirmed the accuracy of control algorithms.