Research On Speed Sensor-Less Indirect Stator Quantities Control Of Traction Motor

As the key of mass transit vehicles, traction system determines the vehicle’s performance and safety directly. With the development of Power Electronic Devices and Digital Signal Processing Technology, the AC drive control technique for high-power traction also obtained rapied developing, Direct Torque Control which resort unique design idea and simple control structure showing itself in many motor control strategies, however this control technique has a torque ripple, stator current distortion and other shortcomings in Lower switching frequency. In addition, the speed sensor often failure due to the bad operation environment, therefore, studying the Speed Sensor-less Technology have important academic value and project significance.Firstly reviewed the development of AC driver control technique, which include power electronic devices, motor control strategy, and Speed Sensor-less Technology, then summarized the influence of Digital Signal Processing on this development. Mathematical model of inverter, the concept of voltage space vector, and the theory of voltage space vector modulation (SVPWM) are clarified based on mathematical model of asynchronous motor.According to the problem of torque ripple in Direct Torque Control system, Indirect Stator-Quantities Control (ISC) of full range of speed traction motor is studied. Considering that traction motor work at rated speed or above frequently, a dynamic Flux-weakening scheme which based on ISC control was finally chosen, after the comparative analysis of two Flux-weakening method. Aiming at the PWM inverter dead-time will influence the calculation of the inverter output voltage inevitable, one method of dead-time compensation strategy was introduced, and have been verified by simulation results.A accurate real-time stator flux is need in DTC control, but traditional stator flux observer has problems such as integration error and poor robustness for the motor parameters, therefore two stator flux observer methods which based on Modern Control Theory was studied in this paper to solve system instability caused by observation error. Moreover, based on Model Reference Adaptive System (MRAS) theory and Sliding Mode theory, Popov ultra-stability rules and Lyapunov second stability principle are applied to derive each speed adaptive algorithm which correctness has been verified by simulation platform. In traction driver system, inverter pulses will block owning to transient overcurrent or overvoltage, passing over of neutral section, inertia operation and other reasons, speed sensor-less algorithm will failure simultaneous, in order to avoid torque shock and overcurrent when the inverter pulses was connected at unknown speed, a restarting strategy was discussed and verified by simulation.With TMS320F2812 DSP of TI Company as the main control chip, three-phase asynchronous motor control board is designed to complete the three-phase asynchronous motor control platform with the existing rectifier bridge, inverter Bridge and traction motors on the foundation of Peripheral Hardware Circuit design of motor control.The feasibility of speed identification algorithm has been proved in the experiment platform at last.