Miniaturization Design Method and Performance Evaluation of Prototype Permanent-Magnet Synchronous Motor Optimally Designed by Thermomagnetic Field Coupling Analysis

Abstract

This paper reports the results of the miniaturization design of a permanent-magnet synchronous motor, for which an optimal design technique based on thermomagnetic field coupling analysis is used. We derived the optimal solutions for various motor flatness ratios and determined the relationship between the motor size and the flatness ratio. For motors with different flatness ratios, we calculated the speed-torque characteristics by considering the voltage, temperature rise, and demagnetization limits and compared them. Moreover, we manufactured and tested the smallest designed motor. The measured temperature rises demonstrated the high accuracy of the proposed miniaturization design.

Optimal Design of Permanent Magnet Motor with Magnetic Gear and Prototype Verification

“…Table 1 lists the specifications of the motor designed and prototyped using coupled thermomagnetic field optimization [3]. Table 1 lists the specifications of the motor designed and prototyped using coupled thermomagnetic field optimization [3].…”

“…The material properties are reconsidered in terms of the temperature results and the cross-sectional shape of the magnetic circuit is optimized so that the output density is at a maximum [3,4]. First, the output characteristics and losses are calculated by magnetic field analysis, thermal analysis is performed on the basis of the losses thus obtained, and the temperatures of the components are calculated.…”

“…Thus, the cross-sectional shape of the motor is determined by solving the optimization problem for objective function (1) [3,4]. Because the rotational speed of the output shaft is constant, increasing the output density (output vs. motor configuration) is equivalent to maximizing the torque density.…”

“…During the optimization calculations, components subject to degradation are taken into consideration, and the following three constraints are set [3,4]:…”

Extension of Mathematical Models Taking Temperature Variation in Permanent Magnet Synchronous Motors into Consideration

“…This results in deterioration of material properties such as decline of residual flux density B r of permanent magnets and growth of winding resistance, thus impairing motor's torque characteristics. In this context, motor design was proposed with regard to balance (trade-off) between frame size and temperature rise [5].…”