Calculation And Research Of Reactance For Permanent Magnet Synchronous Motor With Multi-Pole And Few-Slot

Reactance parameter of permanent magnet synchronous motor (PMSM) with multi- pole and few-slot is one of the key parameters in motor design, whose accuracy of calcu- lation 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 with multi-pole and few-slot. Specific work can be divided to the following parts: Firstly, the existing calculation methods for reactance parameter of PMSM are summarized and studied. The calculation method of reactance parameter for PMSM with multi-pole and few-slot is detailed researched. 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 regarded in calculation process. This paper provided two calculation methods of reactance parameter that taking cross saturation into account, permeability frozen method and load method.Calculations of quadrature and direct axis reactance parameters for many sets of surface-mounted and interior PMSMs are carried out using these two methods. Plenty magnetomotive space harmonic emerged in PMSM with multi-pole and few-slot.Secondary, the testing method for reactance parameter of permanent magnet motor with multi-pole and few-slot 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 PMSMs with multi-pole and few-slot is voltage integral method considering the cross saturation. Its calculation method adopts the load method. With the error between the calculation value and test result less than 10 percentages, the calculation method is valid. In the end, through the calculation of reactance parameter for many sets of PMSMs with multi-pole and few-slot, 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.