On The DC-link Voltage Fluctuation Of Permanent Magnet Traction System In High-Speed Train

With high capacity,high speed and high degree of comfort of passengers,the high speed railway transportation has been widely developed and applied around the globe.Meanwhile,high speed train traction system based on permanent magnet synchronous motor(PMSM)have advantageous characteristics such as high power density,high efficiency and easiness to control,and has become the focus of research for manufacturing and technology powers such as Japan,France,Germany and China.Base on this background,this thesis concerns the high speed train traction converter system,and studies the origin,specific characteristics of influences on the PMSM drive and corresponding mitigation methods of dc-link voltage fluctuation.The main contents and contributions of this thesis are:(1)The origin of the dc-link voltage fluctuation with the normal operation of the single-phase pulse width modulated(PWM)rectifier is investigated.Dc-link voltage models with two different types of load,namely constant power load(CPL)and resistive load(RL),are established and compared.A unified expression is summarized to approximate both models.(2)Model of the coupling harmonics,stemming from the dc-link voltage fluctuation,on the ac side of single-phase PWM rectifier is established using multi-dimensional Fourier series.Then the principle of the typical compensation methods of carrier and modulation wave adjustment is accurately analyzed and validity proved using the approximate solution of integration boundary functions with this model.(3)Different types of models of the coupling harmonics,stemming from the dc-link voltage fluctuation,on the output voltage of three-phase traction inverter and on the winding current of PMSM are established with respect to the respective synchronous modulation modes,and corresponding coupling harmonic current and torque suppression methods proposed.For synchronous space vector modulation(SSVM)mode,complex-frequency-domain vector analysis is employed to obtain a generalized model,and the suppression is proposed,based on the equalization of output voltage vector effect in every individual carrier cycle.For selected harmonics elimination pulse width modulation(SHEPWM)method,multi dimensional Fourier series equivalent switching function is used,and the suppression is proposed,based on the equalization of stator flux in evenly distributed sections.(4)Model of the dc-link voltage fluctuation with the uncontrolled operation of the single-phase PWM rectifier is established using resistive load condition approximation.A repetitive dc-link voltage predictor is employed to accommodate the previous suppression methods under this condition.The influence of dc-link voltage fluctuation on the PMSM in square-wave mode is investigated,and a torque ripple suppression and fast dynamic control method for PMSM in this mode is proposed.