Equivalent stator slot model of temperature field for high torque-density permanent magnet synchronous in-wheel motors accounting for winding type

Abstract

Purpose – For high torque-density permanent magnet synchronous in-wheel motor, service life and electromagnetic performance are related directly to winding temperature. The purpose of this paper is to investigate the equivalent stator slot model to calculate the temperature of winding accurately. Design/methodology/approach – This paper analyzes the the law of heat flux transfer in slot, which points the main influence factors of equivalent stator slot model. Thermal network model is used to investigate the drawbacks of conventional equivalent model. Based on the law of heat transfer in stator slot, a new layered winding model is put forward. According to winding type and property of impregnations, detailed method and equivalent principle of the new model are presented. The accuracy of this new method has been verified experimentally. Findings – An accurate equivalent stator slot model should be built according to the low of heat transfer. According to theory analysis, the drawbacks of conventional equivalent stator slot model are pointed: it cannot reflect the temperature gradient of winding; the maximum and the average temperature of winding are much higher than actual value. For the new layered model, equivalent principle is related to winding type and property of impregnations, which makes the new model widely used. Originality/value – This paper presents a new layered model, and shows detailed method, which is more meaningful for designers. The new layered model takes winding type and property of impregnations into account, which makes the new model widely used. It is verified experimentally that layered model is applicable to not only steady-state temperature field but also transient temperature field.

Temperature Field Accurate Modeling and Cooling Performance Evaluation of Direct-Drive Outer-Rotor Air-Cooling In-Wheel Motor

“…The layer insulations and the air inside the slot are disregarded. The remainders in the slot are divided into equivalent insulations and pure copper [21]. (2) The end windings are equivalent to annular bodies because the end windings are substantially short for the motor.…”

End‐winding wire‐insulation heat conduction model for precise thermal predictions of permanent magnet synchronous machines

“…Currently, many research works have been conducted to balance the accuracy and the complicity of wire-insulation equivalent models. Among those models, four approaches are most usually used: the anisotropic equivalent model [7,8], uniform insulation layer model [9][10][11], multi-layer wireinsulation model [12,13] and thin guided strip model [14,15]. The anisotropic model, as shown in Figure 1(b), bunches the copper wires and insulation layers into anisotropic bars and the thermal conductivity of the bars in different directions differ [7].…”

“…The equivalent insulation layer model equates all the insulation sheets, painting coats and fillings to uniform insulation layers that fit snugly against the slot wall, and all the copper wires to copper conductors covered by the equivalent insulation layers, as shown in Figure 1(c) [10]. Alternatively, to improve the accuracy of the calculations, multi-layer structures were proposed, as shown in Figure 1(d), with finely divided insulation layers and copper layers [12,13]. Moreover, the fine-guided bar model also evolved from the insulation layer model by taking into account the distribution characteristics of the windings.…”

Iron loss research of amorphous alloy motor by considering the influences of solidifying and annealing on stator core

“…People's pursuit of permanent magnet motors with higher efficiency, torque density and power density never stops (Kruchinina et al, 2017;Liang et al, 2016;Liu et al, 2016). With the development of material science and technology, one effective way to achieve this goal is to replace the silicon steel (SS) cores with higher-grade materials (Shim et al, 2016), such as amorphous alloy (AA) material (Silveyra et al, 2016;Hong et al, 2013).…”