### Abstract

In this paper, switched flux permanent magnet (SFPM) machines are analyzed from the perspective of the air-gap field harmonics. It is found that the modulation of the salient rotor to PM and armature reaction fields in SFPM machines is similar to that of the iron pieces to those fields in the magnetic gear and magnetically geared machine. The magnetic gearing effect is analyzed in SFPM machines with different stator/rotor pole combinations, winding configurations, and stator lamination segment types by a simple magnetomotive force-permeance model, and validated by finite-element (FE) analysis. Different from fractional-slot surface-mounted PM machines in which the working air-gap field harmonic generates >95% of the average electromagnetic torque, >95% of the average electromagnetic torque in SFPM machines having \boldsymbol {p}-{\boldsymbol {s}} stator pole pairs and n-{r} rotor poles are contributed by several dominating field harmonics, i.e., rotating ones with \vert kn-{\boldsymbol {r}}\,\pm \, (\textbf {2}\boldsymbol {i}-\textbf {1})\boldsymbol {p}-{\boldsymbol {s}}\vert pole pair ( \boldsymbol {k}=\textbf {1}, \boldsymbol {i}=\textbf {1, 2, 3} ) and static ones with (2\boldsymbol {i}-\textbf {1})\boldsymbol {p}-{\boldsymbol {s}} pole pair ( \boldsymbol {i}=\textbf {1, 2, 3} ). The FE predicted average static torques in SFPM machines are validated by measurements on prototype machines.

Original language | English |
---|---|

Article number | 7038147 |

Pages (from-to) | 1-12 |

Number of pages | 12 |

Journal | IEEE Transactions on Magnetics |

Volume | 51 |

Issue number | 5 |

Early online date | 10 Feb 2015 |

DOIs | |

Publication status | Published - 1 May 2015 |

### Keywords

- Flux switching
- harmonic analysis
- magnetic gear
- magnetic gearing effect
- magnetically geared machine
- modulation
- permanent magnet machines
- switched flux

### ASJC Scopus subject areas

- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering

### Cite this

**Analysis of air-gap field modulation and magnetic gearing effects in switched flux permanent magnet machines.** / Wu, Z. Z.; Zhu, Z. Q.

Research output: Contribution to journal › Article

*IEEE Transactions on Magnetics*, vol. 51, no. 5, 7038147, pp. 1-12. https://doi.org/10.1109/TMAG.2015.2402201

}

TY - JOUR

T1 - Analysis of air-gap field modulation and magnetic gearing effects in switched flux permanent magnet machines

AU - Wu, Z. Z.

AU - Zhu, Z. Q.

PY - 2015/5/1

Y1 - 2015/5/1

N2 - In this paper, switched flux permanent magnet (SFPM) machines are analyzed from the perspective of the air-gap field harmonics. It is found that the modulation of the salient rotor to PM and armature reaction fields in SFPM machines is similar to that of the iron pieces to those fields in the magnetic gear and magnetically geared machine. The magnetic gearing effect is analyzed in SFPM machines with different stator/rotor pole combinations, winding configurations, and stator lamination segment types by a simple magnetomotive force-permeance model, and validated by finite-element (FE) analysis. Different from fractional-slot surface-mounted PM machines in which the working air-gap field harmonic generates >95% of the average electromagnetic torque, >95% of the average electromagnetic torque in SFPM machines having \boldsymbol {p}-{\boldsymbol {s}} stator pole pairs and n-{r} rotor poles are contributed by several dominating field harmonics, i.e., rotating ones with \vert kn-{\boldsymbol {r}}\,\pm \, (\textbf {2}\boldsymbol {i}-\textbf {1})\boldsymbol {p}-{\boldsymbol {s}}\vert pole pair ( \boldsymbol {k}=\textbf {1}, \boldsymbol {i}=\textbf {1, 2, 3} ) and static ones with (2\boldsymbol {i}-\textbf {1})\boldsymbol {p}-{\boldsymbol {s}} pole pair ( \boldsymbol {i}=\textbf {1, 2, 3} ). The FE predicted average static torques in SFPM machines are validated by measurements on prototype machines.

AB - In this paper, switched flux permanent magnet (SFPM) machines are analyzed from the perspective of the air-gap field harmonics. It is found that the modulation of the salient rotor to PM and armature reaction fields in SFPM machines is similar to that of the iron pieces to those fields in the magnetic gear and magnetically geared machine. The magnetic gearing effect is analyzed in SFPM machines with different stator/rotor pole combinations, winding configurations, and stator lamination segment types by a simple magnetomotive force-permeance model, and validated by finite-element (FE) analysis. Different from fractional-slot surface-mounted PM machines in which the working air-gap field harmonic generates >95% of the average electromagnetic torque, >95% of the average electromagnetic torque in SFPM machines having \boldsymbol {p}-{\boldsymbol {s}} stator pole pairs and n-{r} rotor poles are contributed by several dominating field harmonics, i.e., rotating ones with \vert kn-{\boldsymbol {r}}\,\pm \, (\textbf {2}\boldsymbol {i}-\textbf {1})\boldsymbol {p}-{\boldsymbol {s}}\vert pole pair ( \boldsymbol {k}=\textbf {1}, \boldsymbol {i}=\textbf {1, 2, 3} ) and static ones with (2\boldsymbol {i}-\textbf {1})\boldsymbol {p}-{\boldsymbol {s}} pole pair ( \boldsymbol {i}=\textbf {1, 2, 3} ). The FE predicted average static torques in SFPM machines are validated by measurements on prototype machines.

KW - Flux switching

KW - harmonic analysis

KW - magnetic gear

KW - magnetic gearing effect

KW - magnetically geared machine

KW - modulation

KW - permanent magnet machines

KW - switched flux

U2 - 10.1109/TMAG.2015.2402201

DO - 10.1109/TMAG.2015.2402201

M3 - Article

VL - 51

SP - 1

EP - 12

JO - IEEE Transactions on Magnetics

JF - IEEE Transactions on Magnetics

SN - 0018-9464

IS - 5

M1 - 7038147

ER -