| With global climate warming and energy issue becoming increasingly severe, a globalupsurge of new energy vehicles development has emerged. Because of the high efficiency,good speed control performance and other advantages, the permanent magnet synchronousmotors (PMSM) is concerned widespread. As the key component of the power of newenergy vehicles, the PMSM directly determines the vehicle performance. The researchwork of this thesis is supported by the Liaoning province Engineering Research Centerfunded projects permanent magnet AC traction motor common key technologies andproduct development. Through theoretical analysis and experiment test, the no load ironloss, stray load loss, thermal management, motor design and calculation technologies andsome other key technical issues of high efficiency, high power density PMSM for electricvehicles(EVs) application are analyzed in-depth.Firstly, the magnetic field characteristics of PMSM when fed from sine voltage andconverters are analyzed in details. On this basis, the finite element method (FEM) isadopted to calculate and analyze the no load iron loss when fed from sinusoidal voltageand converters, and then the experimental test is carried out. The iron loss correction factorof FEM calculation result is presented. The relationship between the no load iron lossincremental ratio and supply voltage modulation ratio is obtained by experiment. Based onthe calculation and test results, an optimization criterion which minimize the no load ironloss named ironloss_index and comprehensive consider the harmonic amplitude of air-gapflux density, pole slot combinations is proposed. Using this optimization criterion, the pole arc factor and rotor cylindrical of different pole slot combination is analyzed in details, andthen the optimal pole arc factor of different pole slot combination and the optimal groovesposition on rotor cylindrical of 8 poles 48 slots structure is given.Secondly, because of distribution complexand difficult to accurately calculation, thetheoretical analysis and FEM calculation of the stray load loss of the PMSM for EVsapplication is presented from the stator, rotor and magnets. The correction factor of thecalculated results is obtained based on the test results. Commence from the stator magneticmotive force (MMF), the analytical expression of stator stray load loss and rotor eddycurrent loss is presented. The influence of the time and spatial harmonics of stator MMF onrotor loss are mainly analyzed. An magnets eddy current loss analytical expression isderived directly from the basic equation of electromagnetic field,and it provides thetheoretical basis for loss reduction. Through the stray load loss test results, the correctionfactor of stray load loss FEM calculation results is obtained, the proportional relationshipof stray load loss to motor input power and the relationship between the stray load lossgenerated by current time harmonics and load torque are also given. Combination with theanalytical expression and FEM, The magnet eddy current loss suppression technology ---magnet segmentation is investigated, and then a common segmentation law is obtained. Atest device is designed for magnet eddy current loss test, the eddy current loss test resultsof different size magnets verified the validity of the results.Thirdly, based on the iron loss calculated results, the cooling system and thermalmanagement are analyzed in details combination the fluid field and temperature field.According to motor installation environment and size characteristics, the spiral structure isdetermined as the suitable cooling structure. The relationship between the thermalcoefficient of water channel and water speed is obtained through the fluid calculation. Theair flow characteristic in the motor is analyzed through the fluid field analysis, and the airflow speed distribution is obtained. On this basis, the steady-state and transient temperature field of 20kW prototype is analyzed; a real-time correction flow chart of motor losses intransient temperature and their correction formulation are given. The temperature testresults verified the correctness of the calculation results. According to the experimentresults, the permitted time of short-time overload with the thermal-load is obtained.Finally, combination the control method of PMSM for EVs application and motordesign technology, the electromagnetic design and calculated method is analyzed. Theinfluence of parameter coordination to efficiency and field weakening performance are alsopresented. Then, the rotor structure, pole slot combination and no load back-EMF arestudied. At last,two PMSM prototypes for EVs which rotor structure is "V一" type and"V" type are designed, manufactured and comprehensive tested. The rated data of thesetwo prototypes is rated power 20kW, rated speed 4500r/min, peak power 40kW, powerdensity greater than 1.5kW/kg, high efficiency area ratio greater than 80%. The gapbetween the test results and analysis results is small, and the correctness of analysis andcalculation method is verified.
|
PDF Full Text Request