The Research About Traction Inverter In Main Driver System Of Metro Vehicles

The devices of the main driver system in subway mainly consist of traction inverter driver equipment with micro-computer control and traction motor . The project meaning localization of device for main driver system is huge , not only can reduce the investment of main drive system, but is useful for carrying out the goal of assure the localization ratio of total railway vehicle and machine-electric device not below 70%. localization of device for main driver system can also accelerate the process of localization of device in metro, boost the development of subway industry too.Firstly, this paper reports the development and actuality of main driver system in metro, indicates the traction inverter in Chinese metro is two-level inverter of VVVF, The control methods, including control of frequency slope , rotor field-oriented vector control and direct torque control, is applied to main driver system. Aim at the stator field-oriented DTC, the big fluctuation of torque wave and bad effect of voltage wave is pointed out in this paper.Secondly, in order to ameliorate disadvantages of traditional direct torque control applied to main driver system in subway, both three-level inverter and direct torque control technology is applied to the main drive system in metro, this method improves the capability of the main drive system in subway. Compared to two-level inverter, three-level inverter has a lot of advantages, such as better output wave, lower frequency of the switch pulse , lower demands for resistant voltage of devices , lower output harmonic component. Three-level traction inverter has been applied to metro vehicles in Japan and Germany. For its simple structure, quick response of motor torque and better robustness of system parameter, direct torque control have been extensively applied to speed regulation system of asynchronous motors. This paper bring forward a new theory which is the induction motor direct torque control system based on three-level inverter, in the theory flux is partitioned to twelve intervals, we can derive eighteen voltage space vectors which make flux round by the observation of flux and calculation of torque. The induction motor direct torque control system based on three-level inverter in this paper have been implemented effectively for its eighteen voltage space vectors, and the harmonic component from inverter is also ameliorated. Finally, the simulation model of the induction motor direct torque control system based on three-level inverter in this paper is built up by using of the SIMULINK toolbox of MATLAB software. Viewing of the simulation result, the induction motor direct torque control system based on three-level inverter in this paper have been implemented effectively for its eighteen voltage space vectors , what's more, the system's control capability is very good .Through the research in this paper , it indicates that both three-level inverter and direct torque control technology is applied to the main drive system in metro, it reduced the harmonic component from inverter and fluctuation of torque wave. The future of the induction motor direct torque control system based on three-level inverter in this paper will be bright.