Electromagnetic Performance Evaluation of an Outer-Rotor Flux-Switching Permanent Magnet Motor Based on Electrical-Thermal Two-Way Coupling Method

Abstract

Flux-switching permanent magnet (FSPM) motors have gained increasing attention in electric vehicles (EVs) applications due to the advantages of high power density and high efficiency. However, the heat sources of both permanent magnet (PM) and armature winding are located on the limited stator space in the FSPM motors, which may result in the PM overheating and irreversible demagnetization caused by temperature rise, and it is often ignored in the conventional thermal analysis. In this paper, a new electrical-thermal two-way coupling design method is proposed to analyze the electromagnetic performances, where the change of PM material characteristics under different temperatures is taken into consideration. First, the motor topology and design equations are introduced. Second, the demagnetization curves of PM materials under different temperatures are modeled due to PM materials are sensitive to the temperature. Based on the electrical-thermal two-way coupling method, the motor performances are evaluated in detail, such as the load PM flux linkage and output torque. The motor is then optimized, and the electromagnetic performances between initial and improved motors are compared. Finally, a prototype motor is manufactured, and the results are validated by experimental measurements.

Design and Implementation of a Low Power Outer-Rotor Line-Start Permanent-Magnet Synchronous Motor for Ultra-Light Electric Vehicles

“…Considering the placements of the magnets in the rotor laminations for the studied models, the core slots are determined according to the slot pitch and number of slots per phase, by Equations (12,13) respectively, as given Table 3. In this table, the S parameter is the number of the slots on the rotor.…”

“…However, the limited stator area causes overheating, flux saturation and demagnetization. Therefore, thermal analysis is required to determine the demagnetization at different temperatures as it was emphasized in Shu et al [12]. Especially, the maximum torque improved, sufficient mechanical power and more efficiency can be obtained by proper alignment of the magnets for an outer rotor PM Synchronous Motor (OR-PMSM) while keeping the minimum value of cogging torque and low torque ripples [13].…”

Multi-Objective Optimization Design and Multi-Physics Analysis a Double-Stator Permanent-Magnet Doubly Salient Machine

“…The heat flow in the optimal DSPM is analyzed based on the electromagnetic-thermal coupling method [20,21]. Initially, internal heat generation in the motor is obtained by the calculation of total losses, which is then imported to steady-state thermal analysis.…”

Quantitative Comparisons of Six-Phase Outer-Rotor Permanent-Magnet Brushless Machines for Electric Vehicles

“…In this way, it is capable of achieving a high electric frequency at low rotation speed [14]. Meanwhile, it always adopts a concentric winding layout in order to have short end windings, which is more suitable for the limited space of EVs., The general advantages and disadvantages of the four different types of machines are summarized in Table 1 [15][16][17]. Moreover, multiphase machines with a higher degree of freedom have fault-tolerant capability, so they are suitable for EVs, and can also be considered a great option [18,19].…”