# A Review of Torque Ripple Reduction Design Methods for Radial Flux PM Motors

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## Abstract

**:**

## 1. Introduction

## 2. Torque Ripple Reduction Design Methods

#### 2.1. General Classification

#### 2.2. Slot/Pole Number Combination

#### 2.2.1. Fractional Slot/Pole Number Design

#### 2.2.2. Similar Number of Slots and Poles Design

#### 2.3. Stator Winding Type

#### 2.3.1. Use of Distributed Winding

#### 2.3.2. Use of Non-Overlapping Windings

#### 2.3.3. Coil Distribution and Turn Ratio Variation

#### 2.4. Geometry Optimization

#### 2.4.1. Asymmetric Rotor Design

#### 2.4.2. Special Permanent Magnets Magnetization Direction

#### 2.4.3. Magnet Skewing

#### 2.4.4. Unequal Teeth Widths Design

#### 2.4.5. Stator Teeth and Magnets Surfaces Notching

#### 2.4.6. Magnets Shaping

#### 2.4.7. Staggered Rotor Design

#### 2.4.8. Eccentric Structure of Stator Teeth Design

## 3. Discussion

## 4. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

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Reference | Machine Topology | Design Technique | Torque Ripple Reduction Ratio (%) | Slot/Pole Number | Rated Power (W) | Average Torque (Nm) | Rated Speed (rpm) |
---|---|---|---|---|---|---|---|

High Torque Density and Low Torque Ripple-Shaped Magnet Machines Using Sinusoidal Plus Third Harmonic-Shaped Magnets [12] | Radial flux, surface permanent magnets | Magnets shaping | 88.50 | 24/8 | 54 | 184 | 2800 |

A Dual Notched Design of Radial-Flux Permanent Magnet Motors with Low Cogging Torque and Rare Earth Material [13] | Radial flux, surface permanent magnets | Gear-shaping the surfaces of magnets and teeth | 62.8 | 18/12 | 80 | − | 10,000 |

Torque Ripple Reduction of Saliency-Based Sensorless Drive Concentrated Winding IPMSM Using Novel Flux Barrier [14] | Saliency-based, interior permanent magnets | Flux barrier design | 28 | 9/6 | 5500 | 45 | 1750 |

Reduction of Torque Ripple in Consequent Pole Permanent Magnet Machines Using Staggered Rotor [15] | Consequent-Pole permanent magnet motor | Staggered rotor design | 60 | 9/6 | − | 2.13 | 1500 |

Optimal Design to Reduce Torque Ripple of IPM Motor with Radial-Based Function Meta-Model Considering Design Sensitivity Analysis [16] | Radial flux, interior permanent magnets | Slots, teeth, and magnet size optimization | 58 | 48/8 | 50,000 | 400 | 1200 |

Permanent Magnet Motor Design for Satellite Attitude Control With High Torque Density and Low Torque Ripple [17] | Radial flux, dual rotor | Slotless windings and Halbach array magnets | 67 | 9/8 | 11.5 | 32.15 m | 6000 |

Optimization of Torque Ripples in an Interior Permanent Magnet Synchronous Motor Based on the Orthogonal Experimental Method and MIGA and RBF Neural Networks [18] | Radial flux, interior permanent magnets | Stator, rotor, and magnets sizes optimization | 84 | 24/8 | 5010 | 4.2 | − |

Asymmetric Rotor Design of IPMSM for Vibration Reduction Under Certain Load Condition [19] | Radial flux, interior permanent magnets | Asymmetric rotor shape | 33.10 | 12/8 | 5000 | 24 | 2000 |

Ferrite PM Optimization of SPM BLDC Motor for Oil-Pump Applications, According to Magnetization Direction [20] | Brushless DC | Parallel magnetization direction of permanent magnets | 69.20 | 12/8 | 126 | 0.33 | 3200 |

Design and Analysis of Halbach Ironless Flywheel BLDC Motor/Generators [21] | Brushless DC, outer rotor | Halbach array magnets | 20 | 6/8 | − | 800 m | 40,000 |

Design Optimisation of an Outer Rotor Permanent Magnet Synchronous Hub Motor for a Low-Speed Campus Patrol EV [22] | Radial flux, outer rotor | Similar number of slots and poles | 29 | 51/50 | − | 94.5 | 600 |

Effect Comparison of Zigzag Skew PM Pole and Straight Skew Slot for Vibration Mitigation of PM Brush DC Motors [23] | Brush DC | Zigzag skewed magnets | 37.5 | 24/4 | 800 | 2.147 | 2700 |

Analytical Prediction and Optimization of Cogging Torque in Surface-Mounted Permanent Magnet Machines With Modified Particle Swarm Optimization [24] | Radial flux, surface permanent magnets | Air-gap length and magnet thickness optimization, fractional slot-pole number, and parallel magnetization of permanent magnets | 92.48 | 12/8 | − | − | − |

Material-Efficient Permanent Magnet Shape for Torque Pulsation Minimization in SPM Motors for Automotive Applications [25] | Radial flux, surface permanent magnets | Magnets shaping and skewing | 86.1 | 6/4 | 264.4 | 0.5053 | 1000 |

Modeling of Novel Permanent Magnet Pole Shape SPM Motor for Reducing Torque Pulsation [26] | Radial flux, surface permanent magnets | Magnets shaping | 72.08 | 6/4 | 340.48 | 0.6503 | 5000 |

Reduction of Torque Ripple Caused by Slot Harmonics in FSCW Spoke-Type FPM Motors by Assisted Poles [27] | Spoke-type | Fractional slot concentrated winding and assisted poles | 40 | 12/10 | − | 6.5 | 1500 |

Torque Ripple Reduction in Five-Phase IPM Motors by Lowering Interactional MMF [28] | Radial flux, interior permanent magnets | Asymmetrical rotor poles shifting | − | 40/8 | − | 10.45 | 1500 |

Torque Ripple Reduction of a Salient Pole Permanent Magnet Synchronous Machine, with an Advanced Step-Skewed Rotor Design [29] | Salient-pole, surface permanent magnets | Eccentric airgap, advanced step-skewed rotor, and pole shoes skewing | 91 | 36/4 | 1500 | 10.52 | 1500 |

Efficient Utilization of Rare Earth Permanent-Magnet Materials and Torque Ripple Reduction in Interior Permanent-Magnet Machines [30] | Radial flux, interior permanent magnets | Rotor made by segments arranged in the axial direction, and pole shaping | 50 | 48/8 | 68,000 | 210 | 3080 |

Investigation of Short Permanent Magnet and Stator Flux Bridge Effects on Cogging Torque Mitigation in FSPM Machines [31] | Flux-switching | Short magnet and stator flux bridge | 32.70 | 12/10 | 500 | 3.05 | 1500 |

Reduction of Torque Ripple in Inset Permanent Magnet Synchronous Motor by Magnets Shifting [32] | Radial flux, interior permanent magnets | Magnets shifting | 28 | 48/8 | − | 244 | − |

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## Share and Cite

**MDPI and ACS Style**

Suriano-Sánchez, S.I.; Ponce-Silva, M.; Olivares-Peregrino, V.H.; De León-Aldaco, S.E.
A Review of Torque Ripple Reduction Design Methods for Radial Flux PM Motors. *Eng* **2022**, *3*, 646-661.
https://doi.org/10.3390/eng3040044

**AMA Style**

Suriano-Sánchez SI, Ponce-Silva M, Olivares-Peregrino VH, De León-Aldaco SE.
A Review of Torque Ripple Reduction Design Methods for Radial Flux PM Motors. *Eng*. 2022; 3(4):646-661.
https://doi.org/10.3390/eng3040044

**Chicago/Turabian Style**

Suriano-Sánchez, Sergio I., Mario Ponce-Silva, Víctor H. Olivares-Peregrino, and Susana E. De León-Aldaco.
2022. "A Review of Torque Ripple Reduction Design Methods for Radial Flux PM Motors" *Eng* 3, no. 4: 646-661.
https://doi.org/10.3390/eng3040044