V型游标永磁电机功率因数内在机理及其提升方法

Production Mechanism of Power Factor of V-Type Vernier Permanent Magnet Machine and Improvement Method

基于功率因数内在机理的研究,提出一种提升游标永磁电机(VPM)功率因数的设计方法,该方法采用分层优化,对影响电机功率因数的主要因素,即永磁磁链和同步电感,分别进行了理论推导和优化分析。该文首先对永磁磁链进行了优化设计,利用气隙谐波作为电机结构设计与电机电磁性能之间的中间桥梁,一方面,气隙谐波作为电机参数的设计目标,另一方面,也作为电机功率因数和其他相关电磁性能的设计变量。基于永磁磁链的分析,进一步优化相关参数对同步电感的影响,从而最终确定了VPM电机的优化设计方案。此外,为了验证该方法的有效性,对优化前后电机的电磁性能进行了分析评估。最后对优化后的电机进行了加工和实验测试,理论分析和实验结果表明所提出的VPM电机功率因数优化设计方法的有效性和合理性,提升了VPM电机在轮毂电机直接转矩驱动系统中的应用潜力。

In recent years,Vernier permanent magnet(VPM)machines have attracted increasing attention due to the advantages of high power density at low speed in the research field of electric vehicles(EVs),aerospace actuation,and ship propulsion.However,compared with traditional PM machines,VPM machines generally suffer from a low power factor due to increased PM pole number and flux leakage.Various methods have been proposed from the perspective of machine design to enhance the power factor of VPM machines.However,current research often focuses on the design and optimization of VPM,while the power factor improvement from the theory perspective needs to be addressed.Consequently,in this paper,the power factor mechanism of the magnetic field modulation machine is investigated based on the principle of magnetic field modulation,and a power factor improvement method is proposed for VPM.Taking the V-type Vernier permanent magnet machine(VTVPM)as an example,the inherent mechanism of the power factor of the VTVPM is theoretically studied,and the formulas are derived from the permanent magnet flux linkage layer and synchronous inductance layer using the hierarchical optimization strategy.Firstly,according to the classical power factor formula of the machine,the power factor of the machine is mainly related to the permanent magnet flux linkage and synchronous inductance.Therefore,this paper,from the perspective of optimizing the permanent magnet flux linkage and synchronous inductance,taking harmonics as a bridge,derives and establishes the internal relationship between the permanent magnet flux linkage and synchronous inductance with the design parameters.By the scanning analysis of the parametersθtr andθv of the permanent magnet flux layer motor,it can be concluded thatθtr andθv obtain extreme values at 1.5°and 56°,which is the optimal design of the VTVPM motor,and the amplitude of the fundamental wave of the permanent magnet flux linkage is increased from 135.4 mWb to 149.2 mWb.The synchronous inductance layer combines the sensitivity analysis and response surface methods to reduce the synchronous inductance from 11.1 mH to 9.59 mH.Finally,the power factor is increased from 0.54 to 0.67.In addition,the fundamental amplitude of the back EMF is increased from 65 V to 97 V,and the optimized machine load torque is close to 76.94 N·m,increased by 18.07%.Moreover,the torque ripple is reduced from 2.60%to 1.73%.The simulation results verify the feasibility of the optimization design method.Based on the study of power factor production mechanism of the field modulated machine,this paper presents an optimal design method for the power factor of the VPM machine.The proposed design method adopts hierarchical optimization to theoretically deduce and optimize the permanent magnet flux linkage and synchronous inductor layers,respectively.The power factor and other electromagnetic performance of the machine before and after optimization are compared.Finally,the prototype machine is built,and the basic experiments are carried out.Both the theoretical analysis and experimental results verify the effectiveness and rationality of the proposed optimization design method.