Research On Speed Sensorless Vector Control Strategy For Metro Vehicle

As a new type vehicle in modern city rail traffic, the metro has the characteristics of fast and convenient. The traction control system is the key technology of the metro vehicle. The speed sensorless vector control contributes to improve the stability of the metro vehicle traction control system and reduce the cost. Under the background of the metro vehicle, the thesis has done some research on the speed sensorless vector control. The main work is as follows.To meet the demands of wide speed range and rapid torque response for the metro vehicle, the speed sensorless control is based on the rotor field oriented vector control. The thesis proposes an improvement scheme of vector control at high speed region and a control strategy in the field-weakening region. For the characteristics of low switching frequency on the metro vehicle, the multi-mode PWM modulation control strategy is proposed, which meets the requirement of good harmonic performance at the different frequency modulation ratio in the whole speed region.The key of speed sensorless control is the speed estimation. The thesis studies three schemes of speed sensorless control. The three schemes are the speed estimation based on the rotor back EMF, the full order adaptive state observer and the stator current MRAS. The thesis presents the basic principle of these three speed estimation schemes and analyses the stability of traction control system. Meanwhile, some researches about motor parameters sensitivity have been finished and a method of stator resistance identification has been proposed which can reduce the influence of the change of motor parameters to speed estimation.The thesis has a simulation analysis based on the dspace semi physical simulation platform. The thesis does some researches to simulate different operation of the metro vehicle to verify the accuracy of the speed estimation and the stability of the traction control system. Then the simulation has been finished to study the sensitivity of motor parameters changing to speed estimation and the stability of the traction system. The method of the stator resistance identification has been verified through simulation. Finally three speed estimation schemes have been compared.According to the previous theoretical analysis and simulation, experiments have been operated on the180kW metro vehicle traction control experimental platform. The validity and the stability of the speed sensorless control have been verified. At last the conclusion has been achieved that the full order adaptive state observer is the best control strategy for the metro vehicle.