Research On Test Method Of Permanent Magnet Synchronous Traction Motor

Permanent magnet synchronous motor(PMSM)is becoming the next generation of traction motor for high-speed trains because of its excellent performance and significant energy saving effect.Motor test is the key to the motor performance evaluation,and the effective acquisition of the parameters is crucial to the improvement of the early design and the optimization of the later control strategy.As the development process of PMSM in the field of rail transit is short,study on test method for this type motor is not perfect.Thus,this research has important theoretical significance and engineering application value.Firstly,the mathematical model of interior PMSM is established.The existing load angle calculation method is introduced.And the influence of short circuit current,back electromotive force(EMF),permanent magnet flux linkage and dq-axis inductances change on the motor performance is also analyzed.All of these lay the theoretical foundation for test method research.Secondly,in order to study the feasibility of three-phase steady-state short-circuit current test under non-rated speed,the condition in which the three-phase steady-state short-circuit current is approximated to speed-independent is analyzed with simulations carried out in Maxwell.A new dq-axis inductances test method with phases B and C power supplied is proposed to solve the problem of inaccuracy of rotor positioning by galvanometers.Based on contrasting analysis,it is concluded that the line-to-line method is suitable for the verification of cold inductance parameters,while the proposed method is suitable for studying the influence of dq-axis current variation on the inductances.Thirdly,in order to separate the parameters effectively in iron loss equivalent circuit models of the single-phase and the DQ-axis,the existing load angle calculation method is improved,and the influence of the traditional iron loss equivalent resistance(Rv)is eliminated.Aiming at solving the difficulty of computing Rc caused by the complicated measurements of load angle and the strong coupled parameters,the load angle iteration method and the Rc indirect calculation method is studied,which enhances the convenience of electrical losses analysis from the perspective of equivalent circuits.Comparing the analysis methods for the two kinds of models,it is concluded that the DQ-axis iron loss equivalent circuit model is more accurate and practical.Finally,the convenience and effectiveness of the line-to-line method in direct verification of cold inductance parameters are proved.And based on the motor load test,the effectiveness of the load angle iteration method and the R,calculation method including the superiority of DQ-axis iron equivalent circuit model are verified.