Abstract:

At present, the electro-pneumatic combined braking method is generally adopted in the traction drive system in China, which has disadvantages such as the passenger’s comfort decline caused by the switching of electric braking and pneumatic braking at low speed, weak controllability of pneumatic braking and serious wear of brake shoes. In order to solve this problem, an electric braking control technology of the train based on regenerative braking and plug braking is proposed, which can realize the electric braking in the whole speed range. Firstly, according to the relationship between torque and slip frequency under vector control, the torque output capacity of different braking methods at low speed is analyzed. The controllability of braking torque of regenerative braking when stator frequency is greater than zero and plug braking when stator frequency is less than zero is determined. Secondly, through the field orientation of indirect vector control and the flux observation of direct vector control, the realization principle and feasibility of plug braking are proved. Furthermore, a pure electric braking scheme in which regenerative braking is naturally commutated to plug braking in the low-speed range is proposed. Finally, a low power motor towing experiment test is carried out, the experimental results verify that the proposed braking strategy can achieve stable and controllable output of braking torque in low-speed range and the torque is smooth without impact, which improves the electric braking ability of the train in low-speed range.

Key words: Asynchronous traction motor, field orientated control, regenerative braking, plug braking, pure electric braking