Desigh And Temperature Analysis Of Permanaent Magnet Synchronous Motor For Electric Vehicles

Permanent magnet synchronous motors for electric vehicles are different from the traditionalones, which work only in the rated conditions.they work in the whole operating range of speed.Thekey technologies of them,that is, fundamental characteristics,losses and temperature rise,must beresearched in the whole operating field of the motors.Firstly, in this dissertation, the motor desigh principle and basic structure of an8kW tangentialstructure permanent magnet synchronous motor for electric vehicle has been studied. A multi-slicetechnique based on the2-D finite element method is described to study the operation of skewed motor.The advantages and disadvantages of skewed motor and the Straight slot ones are simulated andcompared.Secondly, the research mainly focuses on losses, which resulte in thermal problem in themachine, include core loss, winding copper loss, rotor eddy current loss and mechanical loss. In orderto analysis the core loss, flux density distribution and loss desity at the typical positions of stator toothand yoke is investigated. Core loss of differente conditions and operating states is analysed. Copperloss of different stator slot structures and different power supply mode is analysed and compared bothin simulation and experiment. Besides, rotor eddy current loss and mechanical loss are discussed inthis part. To find out the pattens in the losses inside the motor is the key to optimize a better motor.Thirdly, the thesis analyses the thermal field according to heating, electromagnetics and so on. A3-D model of this motor is set up to analyse the thermal field inside in it.Several mesures ofequivalent is adapted to simplify the calculation and simulation. The effective heat transfercoeddicient of rotational air is determined and the heat transfer coefficients of each surface arecalculated according to those empirical equations. On that base, the thermal field is analysed and thedistribution maps of different cases are provided.Finally, the permanent magnet prototype for electric vehicle with rated speed of2400r/min hasbeen tested. The losses and temperature rise of the machine are measured at different speed in no loadand load condition. The results of both simulation and experiment are contrasted.Several usefulconclusions are obtained, which may be meaningful for the design of permanent magnet synchronousmotor for electric vehicle.