Crh3 Type Emu Power Traction Control System

The traditional direct torque control through direct control of torque and flux to indirectly control the current, without complex rotation coordinate transformation, which have advantages of simple structure, fast response and good robustness, but the direct torque control system is difficult to obtain a wide speed range as vector control, Its roots mainly in the poor characteristics of torque in its low-speed, the decline in load capacity and the existence of steady-state torque ripple.This paper analyzes the high-power traction system of the type CRH3 EMU and established a mathematical model of three-phase asynchronous motor, in-depth study of the working principle of the traditional direct torque control, describes the implementation process of the traditional direct torque control algorithm in detail, carried out with the system simulation. And analyses the reasons for relatively large torque ripple exist in DTC algorithm.With problems of the traditional direct torque control system, uses different control strategies in the whole speed range in this paper. In the start-up and low-speed range, using circular flux-oriented manner, to achieve indirect torque control; in constant flux region, high-speed range, using hexagonal flux-oriented direct torque control; in weak magnetic range, using hexagonal flux-oriented, carry out constant power adjustment. And real-time observation of changes in the value of stator resistance with fuzzy observer, get an accurate value of stator resistance, and then according to the U-I model of motor, and a low-pass filter with amplitude and phase compensation, calculate the value of stator flux, thereby reducing the stator flux estimation error due to changes of the stator resistance. Also proposed using fuzzy controller instead of the traditional Band-Band stator flux and torque controller, switch state of inverter control is more precise, reducing the torque ripple, expand the speed adjustable range of the direct torque control system.Apply a specifically control chip for motor control TMS320F2407 DSP, set up a digital direct torque fuzzy control experimental system with the control chip as a core of the device, through the Matlab software simulation results and experimental analysis, the control system is designed improve the stability performance of the running state of the motor, reducing the motor's steady-state torque ripple, expanding the speed scope of the motor.