Permanent magnet machines have many advantages such as high efficiency,high power density and so on,it have been widely used in the fields of aerospace,wind power generation and electric vehicles. However,permanent magnet machines have the disadvantage that the air-gap magnetic field is difficult to be adjusted.To effectively solve this problem,many scholars have proposed a hybrid excitation machine ,in which the electrically excited magnetic potential plays an auxiliary role in adjusting the air-gap magnetic field 1.The hybrid pole permanent magnet machine was proposed2 ,which has a simple structure and high electric excitation efficiency.It has a permanent magnet and ferromagnetic pole structure on the rotor,but it has brush structure.A new hybrid excited consequent pole brushless Doubly Fed Machine (HE-CPBDFM) is proposed in this paper,and the performance of the machine is studied.
Fig.1 gives the structure of the HE-CPBDFM.There are two sets of windings on the stator of the machine,a power winding with 3 pole pairs and a control winding with 1 pole pair;the number of permanent magnets on the rotor is the same as the number of poles of the control winding,and the polarity is the same,and the mechanical angle of the ferromagnetic pole with a smaller circumference between the two permanent magnets is 60°.The direction of the magnetic field synthesized by the control winding is facing the axis of the ferromagnetic pole,and the air gap magnetic field is adjusted by changing the magnitude of the excitation of the control winding.
Keeping the external 220Ω load on the power winding side unchanged,the relationship curves between the power winding output voltage and the control winding excitation current under different excitation are shown in Fig.2. From Fig.2,it can be seen that the power winding output voltage increases with the increase of excitation current,and when the excitation current increases to 4A,the voltage growth rate slows down with the increase of machine saturation.
1 Ullah S, McDonald S P, Martin R, et al. “A permanent magnet assist, segmented rotor, switched reluctance drive for fault tolerant aerospace applications,”. IEEE Trans. on Ind. Appl., vol. 55, no. 1, pp. 298-305,Jan./Feb.2018.
2 Q. Zhang, S. R.Huang, G. D. Xie. “Design and experimental verification of hybrid excitation machine with isolated magnetic paths,”. IEEE Trans. Energy Conversion, vol. 25, no. 4, pp. 993-1000, Dec.2010.
3Ayub M, Jawad G, Kwon B. “Consequent-pole hybrid excitation brushless wound field synchronous machine with fractional slot concentrated winding,”. IEEE Trans. Magn., DOI: 10.1109/TMAG.2018.2890509,2019.
Fig.1.Machine structure diagram
Fig.2.The relationship between the output voltage of the power winding and the excitation current of the control winding under different excitations