# Torque Ripple Reduction of Switched Reluctance Motor with Non-Uniform Air-Gap and a Rotor Hole

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## Abstract

**:**

## 1. Introduction

## 2. Conventional and Non-Uniform Air-Gap Rotors

#### 2.1. Conventional Rotor

#### 2.2. Non-Uniform Air-Gap

## 3. Proposed Rotor with Non-Uniform Air-Gap and One-Hole

#### 3.1. Design of Proposed Rotor

#### 3.2. Simulation Results of Proposed Rotor

- When the hole is located too deep (large ${d}_{h}$) from the rotor-pole face, it has little effect. The change in the other two parameters at this point is unnoticeable.
- The same is applicable for ${r}_{h}$. A greater value of ${r}_{h}$ produces a more noticeable change. However, this still depends on ${d}_{h}.$
- As for ${\beta}_{h}$, the effect is more noticeable when it is closer to the side tip (larger ${\beta}_{h}$), this too depends on ${d}_{h}$.
- It can be supposed that the hole does not affect the average torque by a wide range. The variance of maximum and minimum values from the three sets of figures is less than 3% of the rated torque of 0.24 Nm.
- Torque ripple, however, shows a slightly higher variance of 4.2%.

## 4. Experimental Results

## 5. Discussions

## 6. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 4.**Flux density of conventional 12/8 SRM: (

**a**) Overall motor; (

**b**) Start of overlap re-gion; (

**c**) Turn-off point.

**Figure 7.**Flux density of non-uniform rotor 12/8 SRM (${l}_{g2}=0.15\mathrm{mm}$): (

**a**) Overall motor; (

**b**) Start of overlap region; (

**c**) Turn-off point.

**Figure 9.**Torque characteristic with varying ${d}_{h}$, ${\beta}_{h}$ and ${r}_{h}$: (

**a**) Average torque $\left({d}_{h}=0.05\mathrm{mm}\right)$; (

**b**) Torque ripple $\left({d}_{h}=0.05\mathrm{mm}\right)$; (

**c**) Average torque $\left({d}_{h}=0.30\mathrm{mm}\right)$; (

**d**) Torque ripple $\left({d}_{h}=0.30\mathrm{mm}\right)$; (

**e**) Average torque $\left({d}_{h}=0.55\mathrm{mm}\right)$; (

**f**) Torque ripple $\left({d}_{h}=0.55\mathrm{mm}\right)$.

**Figure 10.**Magnetic characteristic with varying ${d}_{h}$, ${\beta}_{h}$ and ${r}_{h}$: (

**a**) Rotor core loss $\left({d}_{h}=0.05\mathrm{mm}\right)$; (

**b**) Rotor saturation $\left({d}_{h}=0.05\mathrm{mm}\right)$; (

**c**) Rotor core loss $\left({d}_{h}=0.30\mathrm{mm}\right)$; (

**d**) Rotor saturation $\left({d}_{h}=0.30\mathrm{mm}\right)$; (

**e**) Rotor core loss $\left({d}_{h}=0.55\mathrm{mm}\right)$; (

**f**) Rotor saturation$\left({d}_{h}=0.55\mathrm{mm}\right)$.

**Figure 12.**Flux density of proposed 12/8 SRM: (

**a**) Overall motor; (

**b**) Start of overlap region; (

**c**) Turn-off point.

Parameters | Value |
---|---|

Stator outer diameter [mm] | 72 |

Stack length [mm] | 18 |

DC-link voltage [V] | 12 |

Output speed [RPM] | 1800 |

Output torque [Nm] | 0.24 |

Maximum current [A] | 30 |

Parameters | Conventional | ${\mathit{l}}_{\mathit{g}2}$ Value of Non-Uniform Models | ||||
---|---|---|---|---|---|---|

0.05 | 0.10 | 0.15 | 0.20 | 0.25 | ||

Average torque | 1.00 | 1.00 | 1.02 | 1.02 | 1.03 | 1.03 |

Torque ripple | 1.00 | 0.92 | 0.87 | 0.83 | 0.79 | 0.77 |

Parameters | Conventional | Non-Uniform | Proposed |
---|---|---|---|

Average torque [Nm] | 0.24 | 0.25 | 0.25 |

Torque ripple [%] | 114.39 | 95.04 | 92.97 |

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**MDPI and ACS Style**

Lukman, G.F.; Ahn, J.-W.
Torque Ripple Reduction of Switched Reluctance Motor with Non-Uniform Air-Gap and a Rotor Hole. *Machines* **2021**, *9*, 348.
https://doi.org/10.3390/machines9120348

**AMA Style**

Lukman GF, Ahn J-W.
Torque Ripple Reduction of Switched Reluctance Motor with Non-Uniform Air-Gap and a Rotor Hole. *Machines*. 2021; 9(12):348.
https://doi.org/10.3390/machines9120348

**Chicago/Turabian Style**

Lukman, Grace Firsta, and Jin-Woo Ahn.
2021. "Torque Ripple Reduction of Switched Reluctance Motor with Non-Uniform Air-Gap and a Rotor Hole" *Machines* 9, no. 12: 348.
https://doi.org/10.3390/machines9120348