Determination of parameters of a synchronous motor with radial permanent magnets and rotor damper bar cage

Abstract – The paper describes the determination of the parameters of a permanent magnet synchronous motor with radial magnets (RPMSM) as functions of power supply conditions and load. The description presents analysis of some steady state and transient performances together with limitations.

Two methods are presented in the determination of the values of synchronous reactance for “d-axis” Xsd, respectively “q-axis” Xsq together with the evaluation of the core loss equivalent resistance Rc. The two methods described are a load test performed at the nominal frequency and Finite Element Analysis (FEA). The load tests results, including the direct determination of the internal load angle d, represent the input of the calculation process for Xsd and Xsq. The synchronous reactance along each of the axes is then used to calculate the developed torque and compared with the torque values from direct measurements.

Comparative results have been extracted using FEA and both methods illustrate a good agreement. In addition, FEA provided important indications in terms of maximum allowable current during operation, indicating the starting performance conditions also. The paper ends with an indication of the direction for future development.

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