Study Of Reactance Parameter Of Permanent Magnet Synchronous Motor

Reactance parameter of permanent magnet synchronous motor (PMSM) is one of the key parameters in motor design, whose accuracy of calculation and testing related to the performances of the motor. As the magnetic circuit structure of rotor in PMSM is various and has great difference with ordinary synchronous motor, the accurate calculation and testing of motor’s reactance parameters are difficult. In view of this situation, this paper studied the calculation and test method of reactance parameters for PMSM. Specific work can be divided to the following parts:Firstly, the existing calculation methods for reactance parameter of PMSM are summarized and studied. Without considering that the quadrature and direct axis of.stator and rotor in PMSM, the equivalent d-axis state and the equivalent q-axis state method can be used to calculate the reactance parameter. Considering that the quadrature and direct axis of stator and rotor in PMSM have common magnetic circuit which cannot completely decouple, the influence of cross saturation on reactance parameter should be considered in calculation process. This paper provided one calculation method of reactance parameter that taking cross saturation into account--permeability frozen method. Calculations of quadrature and direct axis reactance parameters for many sets of surface-mounted and interior PMSMs are carried out using the method. Plenty magnetomotive space harmonic emerged in PMSM.Secondary, the testing method for reactance parameter of permanent magnet motor is studied. Experiments are carried out using volt-ampere method and voltage integral method on many sets of motors. Through the comparative analysis of calculation and test results, the testing method suits for Surface-mounted PMSMs can be tested by volt-ampere method. Interior PMSMs can be tested by voltage integral method. In order to consider that the quadrature and direct axis of stator and rotor in PMSM, We can change the special wiring. With the error between the calculation value and test result less than10percentages, the calculation method is valid.In the end, through the calculation of reactance parameter for many sets of PMSMs, the key factors that influence the quadrature and direct axis reactance parameters are analyzed. With the cross saturation taking into account, the variation rule of the quadrature and direct axis reactance parameters with various rotor structure, airgap length, magnetic bridge size, slot open width and magnetization length are summed. Variation range of saliency ratio is given. And the variation rule of saliency ratio changing with air gap and magnetization length is summed.