Inductance Characteristic Analysis of Consequent-Pole Permanent Magnet In-Wheel Motor

Abstract

This paper presents inductance characteristics analysis of the consequent-pole permanent magnet in-wheel motor (CPM). Considering the specialty of consequent-pole structure, this paper analyzes the change rule of the winding self-inductance via equivalent magnetic circuit method (EMCM). The corresponding equivalent resistance is directly given when the rotor is in different positions. Based on this, equivalent magnetic circuit (EMC) that reflects the inductance of the CPM is summarized in this paper. In order to analyze the difference and connection of the inductance among the CPM, two models with 36 slots 32 poles and 48 slots 40 poles are established and compared. Moreover, the Fourier analysis expression of winding self-inductance is deduced to prove the different periodicities of winding self-inductance between two motors. The experimental result is consistent with the theoretical analysis, and the conclusion effectively proves the close relationship between the inductance characteristics and its internal structure of the motor. INDEX TERMS Consequent-pole, equivalent magnetic circuit method (EMCM), self-inductance, periodicity.

Influence of slot/pole number combinations and pole shaping on electromagnetic performance of permanent magnet machines with unbalanced north and south poles

“…The different electromagnetic characteristics found in specific CPPM machines in Refs. [7, 12, 18, 19, 27] underpin the above theoretic analysis and the general conclusions.…”

“…The features of north and south poles in CPPM machines are unequal even if the PM and iron pole widths are the same and it will inevitably result in even order harmonics in air-gap flux density [18] and odd order harmonics in the inductance of a coil [27]. However, additional harmonics do not always exist -3 in winding flux linkage and winding inductance.…”

“…The inductance harmonics can also be derived similarly. It has been found that the inductance in one coil consists of all orders of harmonics in CPPM machines due to only one salient pole in an electrical cycle for a CPPM rotor [27]. However, when the coil number for one phase in a submachine is an even number, namely the second group CPPM machines, the odd order harmonics in inductances of the ith and jth coils will be eliminated since…”

“…The inductance harmonics can also be derived similarly. It has been found that the inductance in one coil consists of all orders of harmonics in CPPM machines due to only one salient pole in an electrical cycle for a CPPM rotor [27]. However, when the coil number for one phase in a submachine is an even number, namely the second group CPPM machines, the odd order harmonics in inductances of the i th and j th coils will be eliminated since $$${L}_{2n-1}^{i}+{L}_{2n-1}^{j}={L}_{2n-1}\left[\mathrm{sin}\left((2n-1)ip\frac{2\pi }{{N}_{s}}+{\theta }_{2n}^{L}\right)\right.+\mathrm{sin}\left((2n-1)ip\frac{2\pi }{{N}_{s}}+(2n-1)\pi \frac{p}{\mathrm{GCD}\left({N}_{s},p\right)}+{\theta }_{2n}^{L}\right)]=0$$$ where $${L}_{2n-1}^{i},{L}_{2n-1}^{j}$$ are the 2 n ‐order harmonics in inductances of the i th and the j th coils, respectively, $${L}_{2n-1}$$ and $${\theta }_{2n}^{L}$$ are the amplitude and the initial position angle of 2 n ‐order harmonic.…”