基于多频对极磁场耦合的直驱型双馈电机电磁耦合特性分析

Analysis of electromagnetic coupling characteristics for doubly-fed induction generator based on multi-frequency pole pairs’magnetic field coupling

常规双馈电机难以通过增加极对数实现直驱。分析分数槽集中绕组的磁场极对数频谱,利用极对数主导分量实现电磁耦合,提出一种基于多频对极磁场耦合的直驱型双馈电机传动方案。针对分数槽集中绕组电机绕组系数在不同极槽比条件下缺乏通用数学解析方法的问题,通过激励磁动势合成,推导3类极槽比的绕组系数一般表达式;对定转子匝数和绕组函数进行傅里叶级数变换,推导各次谐波磁场对应的电感、磁链和感应电压表达式,分析谐波磁场对电机参数的影响;提出一种以特定极对数互感值为指标判据的双转子电机极槽设计方法。通过数学解析和有限元计算结果对比,验证了所提出的多频对极磁场耦合理论和直驱型双馈电机传动原理的正确性。

The direct-drive cannot be realized by increasing pole-pairs for traditional DFIG(Doubly-Fed Induction Generator).The pole pairs’magnetic field spectrum of FSCW(Fractional-Slot Concentrated Windings)is analyzed,and a kind of transmission scheme of multi-frequency pole pairs’magnetic field coupling based direct-driving type DFIG are proposed,which realizes electromagnetic coupling by pole pairs’dominant component.Aiming at the problem that there is no general mathematical calculation method for winding factor of FSCW under different pole-slot ratio,the general winding factor calculation method of three categories of pole-slot ratios are deduced through the synthesis of excitation magneto-motive force.The expressions of inductance,flux linkage and induced voltage corresponding to each harmonic magnetic field are derived based on Fourier series of the number of stator and rotor turns and winding functions,the influence of magnetic field on generator parameters is analyzed.A design method of double rotor motor pole slot based on the specific pole pairs’mutual inductance value is proposed.By comparing the results of mathematical analysis and finite element calculation,the correctness of the coupling theory of the proposed multi-frequency pole pairs’magnetic field and the drive principle of direct-driving type DFIG is verified.