Research On Beat-less Control Strategy For EMUs

With the rapid development of nationwide urbanization, there is a growing demand for intercity transportation. EMU becomes the preferred intercity transport with its flexible marshalling approach and excellent speed performance. Beat phenomenon in EMU traction converters can lead to system loss, severe fever and mechanical shaking. Supported by National Key Technologies R&D Program for the "12th Five-year Plan"—"Research on Hybrid EMU Key Technology and Typical Equipment Development", this thesis proposes a beat-less control scheme. Beat phenomenon in EMU traction drive system is studied to realize weight reduction and lower cost of the train. And the feasibility and effectiveness of the strategy is verified through the simulation and experiment.The vector control system of asynchronous motor is studied, the basic method of coordinate transformation is introduced, the mathematical model of asynchronous motor in synchronous rotating coordinate system is established, different vector control schemes of asynchronous motor are studied, and equivalent circuit is given, basic principle of vector control system based on rotor field oriented is obtained. The theoretical basis of beat phenomenon modeling is established.Beat phenomenon is comprehensively analyzed, DC ripple voltage of single phase four quadrant rectifier is derived based on instantaneous power balance characteristics. The output voltage of inverter is analyzed according to switch function, beat current of asynchronous motor is obtained based on impedance characteristic. The suppression methods of beat phenomenon are studied.The advantages and disadvantages of a variety of control modes are compared.The small signal model of asynchronous motor is set up based on dynamic model. The relationship between beat current, ripple voltage and slip frequency increment is analyzed. The quantitative analysis of beat phenomenon is obtained in frequency domain. In this way, beat current model and beat torque model are established. With beat-less control scheme, the parameters in beat controller are designed. Beat phenomenon is suppressed through the correction of motor slip frequency. In the process of digital implementation in control strategy, the DC ripple voltage is accurately sampled through the design of digital filter and the analysis of discretization method. The beat-less control scheme is applied in rotor field oriented vector control system.The simulation study of beat-less control scheme is carried out with the help of matlab. The EMU traction drive system experimental platform is set up. The beat-less control scheme is experimentally verified. The simulation results and experimental results are consistent with theoretical analysis, through which the effectiveness of the proposed beat-less control scheme in this paper is verified. Figures:62, Tables:2, References:66.