Analysis, Modeling And Optimization Of Metro Traction System

Metro traction system is the core of motor car, which is the key point of the vehicle localization. The adhesion characteristics between wheel and track and the traction motor load characteristics were analyzed in the paper, and the metro traction system model was built accurately. Based on the model, the re-adhesion optimization control and the traction motor connected in parallel were studied. At the same time, the core technology for traction system design were studied, including train characteristics curves design, traction converter and induction motor matching, nominal slip ratio design of traction motor, etc. The following achievements were obtained.The double axle's model in bogie-control mode was built to study the adhesion control, and a re-adhesion optimization control method based on full state observer for traction drive was raised. To perform the maximum utilization of adhesion, a full state observer was built to obtain the motor load torque. Then the adhesion coefficient was calculated to find the adhesion peak zone. A searching algorithm was used to get the optimal slip velocity reference automatically. Then combined the line voltage, train velocity and the master-controller instruction, obtained the torque reference for traction motor control. To study the wheel-track adhesion characteristics, traction drive and the train kinetics performance, the metro traction drive system model was built in Matlab. Simulation and experiment were done.The dissertation deeply analyzed the torque-unbalanced reasons for parallel-connected motor in one bogie and the severe aftereffect. The mathematical relations among torque-unbalance, wheel diameter difference and motor slip ratio were get by formula derivation. An optimal parallel-connected motor control strategy based on re-adhesion optimization utilization and magnetizing compensation was presented. The former generated the torque reference, and the latter regulated the magnetizing reference for motor control according to wheel diameter difference, line voltage and train speed. The slip frequency (i.e. slip ratio) was increased and the torque-unbalanced level was decreased. Simulation and experimental waveforms were given.Considering the macro designing of metro traction drive system, an engineering design method for train traction/braking characteristics curves was presented. In the prerequisite of meeting available adhesion checking, the regeneration feedback energy was full used by traction control, and the loss between brake and wheel were reduced. Analysis showed that the presented train braking characteristics curve achieved energy saving and noise reduction, low-carbon environmental protection objectives.According to characteristics of metro train load intermittent and short-term overload, a suitable traction converter and traction motor "system matching" approach was proposed. Namely, based on train characteristics curves, the capacity of converter designing referred to motor braking peak power, while the traction motor was in accordance with "small motor match" method to select the maximum torque multiplier (subversion torque) at the nominal point, more emphasized on the safety margin of converter capacity and the motor utilization capacity. The successful trial operation of homemade metro traction system verified the proposed "system match" method. Comprehensive consideration the metro traction system macro-design, motor parallel control, and the easy maintenance for subway operators, put forward the designing method for traction motor rated slip ratio and other rated electrical parameters. The motor characteristic curves by experiments meet the requirements of train operating and traction control.A metro traction inverter was developed for type B train. The main circuit, control system, supervision interface and traction calculation software were detailed designed. The effect of the traction motor vector control and traction characteristics was tested, and test results were analyzed.