Development of a Fast Thermal Model for Calculating the Temperature of the Interior PMSM

Abstract

A 40 kW–4000 rpm interior permanent magnet synchronous machine (IPMSM) applied to an electric vehicle (EV) is introduced as the study object in this paper. The main work of this paper is theoretical derivation and validation of the first-order and multi-order transient lumped-parameter thermal network (LPTN) for the development of a fast thermal model. Based on the first-order LPTN built, the study finds that the heat transfer coefficient of fluid and thickness of the air gap layer are the main influencing factors for the final temperature and time of reaching the steady state. The larger the heat transfer coefficient of fluid is, the lower the steady node temperature is. The smaller the air layer thickness is, the lower the steady node temperature is. The multi-order LPTN theory is further deduced based on the extension of the first-order LPTN. For the constant load and rectangular periodic load, transient node temperatures of the IPMSM are obtained by modeling and solving the first order inhomogeneous differential equations. Temperature rise curves and efficiency maps of the IPMSM under load conditions are realized on a dynamometer platform. The FLUKE infrared-thermal imager and the thermocouple PTC100 are used to validate the mentioned method. The experiment shows that the LPTN of the IPMSM can accurately predict the node temperature.

Perspective of Thermal Analysis and Management for Permanent Magnet Machines, with Particular Reference to Hotspot Temperatures

“…The indirect forced liquid cooling system mainly consists of cooling channels, coolants, and pumps. Firstly, the cooling channels can be grooved or installed within the frame [38,46,48,51,[154][155][156], the stator core [157][158][159][160], the slot [161,162], the end-winding [163], and the shaft [164][165][166][167], as presented in Figure 10. Secondly, the liquid coolants could be water, ethylene glycol with water (EGW), or engine oil.…”

“…In terms of conduction heat transfer within a solid, LPTMs are constituted by either "T-type" [34,[60][61][62][63]156] or "I-type" [37,38,65,155] elementary conduction thermal networks, which are used to estimate average ϑ avg and mid-point ϑ mid temperatures, respectively. The one-dimensional (1-D) elementary thermal network in the x-direction is shown in Figure 17, where ϑ x,1 , ϑ x,2 , and P are the boundary conditions and the power loss, respectively.…”

“…In the discrete-time domain, it could be solved directly or approximately by using the well-known Runge-Kutta method [81][82][83][84]. Once the heat fluxes [154] or the temperature rises [155] between two iterative time steps approaches zero, it can be determined that the machine reaches thermal equilibrium.…”