Research And Simulation On Traction And Drive System Of High-speed EMU

High speed EMU and high power locomotive are powered by Electrical Traction and Drive System, which features large power, light weight, small volume, high reliability and low cost. And that accounts for why the system adopts the advanced AC drive system. There are three segments in the Electrical Traction and Drive System:No.1, single-phase PWM rectifier can be regulated by the power; No.2, the frequency of the three-level inverter can be adjusted; No.3, energy conversion can be achieved between asynchronous motor and the mechanical drive system.This thesis focuses on the operation principle of the traction converter, the technique of vector control of asynchronous motors and the traction and braking strategy of EMU. By constructing the Matlab simulation model of the traction and drive system and emulating the operation of the high speed EMU under various conditions (traction or brake), parameters of its performance such as the speed of the EMU, the voltage, the current, the power factor of AC side and the torque, rotating speed and stator current of the traction motor can be obtained, which is of great significance to the design and running of the high speed EMU.Single-phase PWM rectifier simulation system makes the DC voltage in permissible deviation and the AC side power factor close to 1.0 or-1.0. Traction motor vector control simulation system can decouple the excited current and torque current dynamically and thus wins an ideal effect in vector control. Constant speed control system can achieve smooth switching among traction, constant speed and regenerative braking operation, thus avoiding the impulsion of the torque and the current during the switching process.Via the change of the gear ratio and the characteristic line for traction of the EMU, the traction motor speed can be altered, so that the problem of leakage in the gear box of EMU can be resolved. Matlab/Simulink simulation results show that the decrease of the gear ratio can lower the speed of the traction motor; but the output torque and the current of the traction motor can also meet the demand of the high-speed EMU in its running.