# Analysis of Torque Ripple and Cogging Torque Reduction in Electric Vehicle Traction Platform Applying Rotor Notched Design

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## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

#### 2.1. Relevant Equations for Cogging Torque and Torque Ripple

#### 2.1.1. Cogging Torque Equation

_{1}is the inner radius of rotor, and R

_{2}is the outer radius of rotor.

#### 2.1.2. Torque Ripple Equation

_{max}, and it is determined in conditions that satisfy the thermal rating of the inverter. The equations for current and voltage are as follows:

_{ds}and I

_{qs}are the d- and q-axis currents, respectively. V

_{ds}and V

_{qs}denote the d and q-axis terminal voltages, respectively.

#### 2.2. Analysis Model and Specifications

#### 2.3. Test Method

## 3. Comparative Analysis and Results

#### 3.1. Comparative Analysis of Cogging Torque and Torque Ripple According to Notch Position

#### 3.2. Comparative Analysis of Cogging Torque and Torque Ripple According to Notch Shape

#### 3.2.1. Comparative Analysis of Cogging Torque and Torque Ripple According to Changes in Notched Shape

#### 3.2.2. Comparative Analysis of Notch Dimensions for Optimal Design

## 4. Discussion

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 2.**Motor rotor notch design positions: (

**a**) magnet’s inner notches; (

**b**) magnet’s outer notches; (

**c**) magnet’s central notches; (

**d**) magnet’s additional central notches; (

**e**) no notches (basic form).

**Figure 3.**Back electromotive force voltage, cogging torque, and torque ripple according to notch position: (

**a**) back electromotive force voltage; (

**b**) cogging torque; (

**c**) comparative analysis of torque ripple.

**Figure 4.**Notch shape optimization: (

**a**) notch optimization position; (

**b**) notch optimization diagram.

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

Number of Slots | EA | 48 |

Number of poles | EA | 8 |

Capacity | kW | 35 |

Rated Speed | rpm | 10,000–11,000 |

Outside Diameter | mm | 200 |

Inside Diameter | mm | 122 |

Stack Length | mm | 50 |

Air Gap | mm | 0.7 |

Characteristic | V-Shape (a) | V-Shape (b) | V-Shape (c) | V-Shape (d) | V-Shape (e) |
---|---|---|---|---|---|

B-EMF Voltage [V_rms] | 20.68 | 20.87 | 23.03 | 26.45 | 24.08 |

Cogging Torque [Nm] | 1.7 | 1.73 | 2.6 | 1.21 | 1.882 |

Torque [Nm] | 88 | 87 | 93 | 87.66 | 87.62 |

Torque Ripple [%] | 15.9 | 8.04 | 22.58 | 12.9 | 24.41 |

Power [kW] | 36.86 | 36.44 | 38.95 | 36.71 | 36.70 |

Analysis Case | Width [mm] | Radius(2) [mm] |
---|---|---|

1 | 0.75 | 5 |

2 | 0.82 | 6 |

3 | 0.9 | 7 |

4 | 0.93 | 7.61 |

5 | 0.94 | 8 |

6 | 0.96 | 9 |

7 | 0.98 | 10 |

Distance (2) [mm] | Radius (3) [mm] | |
---|---|---|

1 | 0.5 | 2.1 |

2 | 0.78 | 2.5 |

3 | 0.93 | 3.1 |

4 | 1 | 3.5 |

5 | 1 | 4 |

6 | 1.05 | 4.451 |

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**MDPI and ACS Style**

Hwang, M.-H.; Lee, H.-S.; Cha, H.-R.
Analysis of Torque Ripple and Cogging Torque Reduction in Electric Vehicle Traction Platform Applying Rotor Notched Design. *Energies* **2018**, *11*, 3053.
https://doi.org/10.3390/en11113053

**AMA Style**

Hwang M-H, Lee H-S, Cha H-R.
Analysis of Torque Ripple and Cogging Torque Reduction in Electric Vehicle Traction Platform Applying Rotor Notched Design. *Energies*. 2018; 11(11):3053.
https://doi.org/10.3390/en11113053

**Chicago/Turabian Style**

Hwang, Myeong-Hwan, Hae-Sol Lee, and Hyun-Rok Cha.
2018. "Analysis of Torque Ripple and Cogging Torque Reduction in Electric Vehicle Traction Platform Applying Rotor Notched Design" *Energies* 11, no. 11: 3053.
https://doi.org/10.3390/en11113053