Analytical thermal modelling for permanent magnet synchronous motors

Abstract

This paper concentrates on the development and analysis of a new generic steady state thermal model for mapping the heat transfer throughout a permanent magnet synchronous motor by considering its individual components as elements of an overall thermal equivalent circuit. This model includes (a) conduction resistances for the stator laminations and housing, conduction resistances between the copper winding and the stator teeth and yoke, between the housing and the stator, and between the housing and the flange, (b) heat flow in the air-gap for vortex and turbulent flow, (c) natural convection and forced cooling for the housing surface and the mounting flange surface, and (d) radiation resistance for the housing surface and mounting flange. The results obtained from the model are compared with corresponding experimental tests for the stall and rated performance with natural and forced cooling for two different motors, one with a rated speed of 1500 r/min and 130 Nm stall torque having 30 slots and 10 poles, and the other with a rated speed of 3000 r/min, and 15 Nm stall torque having 18 slots and 6 poles. The results achieved demonstrate a good correlation between the experimental results and the theoretical results obtained from the thermal model. The main heat paths and thermal resistances of the motor are: • Convection heat transfer and resistance between the motor housing and the ambient environment • Radiation heat transfer and resistance from the housing • Convection heat transfer and resistance between the motor heat sink plate and the ambient environment • Radiation heat transfer and resistance from the motor heat sink plate • Convection heat transfer and resistance between encoder housing and the ambient environment • Radiation heat transfer and resistance from the encoder housing • Contact resistance between the motor housing and the stator laminations • Contact resistance between the winding and the stator laminations which includes the effect of impregnation and nomax insulation between the winding and stator laminations.• Other conduction resistances such as axial conduction resistances of the motor housing.

Temperature Rise Presentation of Motor of Electric Automobile

“…And the distribution map of temperature field of stator and rotor can be got, finding out temperature of special points and analyzing its cause, which is beneficial to the optimization design of motor. Literature [9] shows how to analyze temperature field of three-phase asynchronous traction motor by this way, and then tells the position of the maximum temperature of motor. Various physical fields of the internal parts of motor are interacted and restricted by each other.…”

An overview of thermal modelling techniques for permanent magnet machines

“…Sometimes, simplifying assumptions are also considered to shorten the simulation time. For instance, it can be assumed that heat sources are uniformly distributed on the surface, the ambient temperature is constant during the study, or some losses are insignificant [41,[43][44][45][46][47][48][49][50][51][52][53][54].…”

Electric Machines and Drives in HEVs

“…Various analytical and numerical methods have been developed for the thermal analysis of various types of electric motors [126][127][128][129][130][131][132][133][134][135][136][137][138]. Time-stepping FEA can provide greater accuracy for the thermal distribution in a motor.…”