# Novel Multi-Physics Computational Simulation of a 10 kW Permanent Magnet Motor for Podded Propulsion

^{1}

^{2}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Specifications and Design Results of a 10 kW SPMSM for Podded Propulsion

^{3}is appropriate. Therefore, an electric motor for a podded propulsor operated in water can be designed with such a TRV value. Although the TRV is an important variable to determine the rotor volume, SR is also important from the mechanical point of view. Generally, an SR between 0.5 and 2.0 is selected considering the inertia and the mechanical stresses of the rotor [20]. An electric motor with a small outer diameter is preferred for the design of a podded propulsor because, with an increase in the motor diameter, the hydraulic efficiency decreases. Therefore, SR above 2.0 was considered appropriate for the proposed models.

_{rms}/mm

^{2}is considered for liquid-cooled electric motors [19]. Although high current density is possible when making a compact electric motor, a lower value than that is considered in relation to unexpected thermal instability events. Therefore, for thermal stability, a value the same as the current density was used instead of the rated current.

## 3. Mechanical Analysis of the 10 kW SPMSMs for Podded Propulsion

#### 3.1. Podded Propulsor for Mechanical Analysis

#### 3.2. Modal Acoustic Analysis Considering Fluid-Structure Interaction (FSI)

#### 3.3. Forced Vibration and Underwater Radiated Noise Analysis

## 4. Conclusions

^{st}natural frequency, and thus a higher vibration response and radiated noise is generated than with the other models. In the future, validation tests of the simulation and experimental results for one of the proposed 10 kW SPMSMs for a podded propulsor will be conducted. Moreover, the comparison of natural frequencies in air and water will be also conducted for the fabricated propulsor.

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 1.**Schematic of electric propulsion drive systems: (

**a**) inboard drive, (

**b**) outboard drive, and (

**c**) podded drive.

Description | Model A * | Model B * | Model C * | |
---|---|---|---|---|

Rated output power [kW] | 10 | |||

Rated rotational speed [rpm] | 600 | 1200 | 1800 | |

Rated torque [Nm] | 159.15 | 79.57 | 53.05 | |

Supply voltage [V_{dc}] | 48 | |||

Current density [A_{rms}/mm^{2}] | 7.6 | |||

Power factor | 0.93 | |||

TRV [kNm/m^{3}] | 68 | |||

Air-gap length [mm] | 0.8 | |||

Fill-factor [%] | 41 | |||

Torque ripple [%] | ≤1.0 | |||

Material | Core | 35PN360 (0.35 mm) | ||

PM | NdFe–N42UH (1.247 T at 60 °C) | |||

Winding | Copper–AWG 18 (ϕ 1.08 mm) |

Description | Model A | Model B | Model C | |
---|---|---|---|---|

Rated output power [kW] | 10.01 | 10.15 | 10.03 | |

Rated rotational speed [rpm] | 600 | 1200 | 1800 | |

Rated torque [Nm] | 159.35 | 80.81 | 53.22 | |

Current density [A_{rms}/mm^{2}] | 7.66 | 7.59 | 7.63 | |

Power factor | 0.931 | 0.930 | 0.930 | |

TRV [kNm/m^{3}] | 68.67 | 68.87 | 68.21 | |

Torque ripple [%] | 0.90 | 0.54 | 0.94 | |

SR | 2.57 | 2.42 | 2.26 | |

Rated current [A_{rms}] | 227 | 225 | 201 | |

Efficiency [%] | 90.20 | 93.17 | 94.37 | |

Total loss [%] | 1081.84 | 744.4 | 598.6 | |

Losses [W] | Copper | 969.5 | 610.3 | 443.3 |

PM | 9.34 | 14.8 | 12.4 | |

Iron | 53.0 | 69.3 | 92.9 | |

Mechanical * | 50 | 50 | 50 | |

Outer diameter of stator [mm] | 173.6 | 150.6 | 135 | |

Inner diameter of stator [mm] | 106.6 | 87.6 | 77.6 | |

Outer diameter of rotor [mm] | 105 | 86 | 76 | |

Thickness of stator yoke [mm] | 8 | 7.5 | 6.5 | |

Stack length [mm] | 268 | 202 | 172 | |

The number of turns per slot | 6 | 5 | 5 | |

The number of strands per turn | 18 | 18 | 16 | |

Parallel branch | 2 | 2 | 2 | |

Resistance per phase [ohm] | 0.006271 | 0.004018 | 0.003657 | |

Active volume of motor [m^{3}] | 0.00639 | 0.00363 | 0.00246 | |

Active weight of motor [kg] | 41.40 | 23.43 | 15.85 |

Description | Structure | |||

Housing | Motor | |||

Core | PM | Shaft | ||

Material | Aluminum | 35PN360 | N42UH | SUS304 |

Density [kg/m^{3}] | 2810 | 7600 | 7650 | 8000 |

Young’s modulus [GPa] | 71.7 | 195 | 153 | 193 |

Poisson’s ratio | 0.33 | 0.25 | 0.24 | 0.285 |

Description | Fluid | |||

Material | Air | Water | ||

Density [kg/m^{3}] | 1.225 | 998.2 | ||

Speed of sound [m/s] | 346.2 | 1482.1 |

Description | Model A | Model B | Model C | |
---|---|---|---|---|

1st natural frequency [Hz] (bending mode) | in air | 172.17 | 213.43 | 239.52 |

in water | 154.98 | 189.18 | 212.58 | |

2nd natural frequency [Hz] (bending mode) | in air | 494.06 | 590.71 | 629.18 |

in water | 475.93 | 558.86 | 601.80 | |

3rd natural frequency [Hz] (bending mode) | in air | 925.53 | 1097.40 | 1209.10 |

in water | 823.67 | 981.53 | 1092.90 |

Description | Model A | Model B | Model C | |
---|---|---|---|---|

Rated rotational speed [rpm] | 600 | 1200 | 1800 | |

Electrical frequency, ${f}_{e}$ [Hz] | 50 | 100 | 150 | |

Pole-passing frequency, ${f}_{pp}$ [Hz] | 100 | 200 | 300 | |

Max. vibration response displacement [μm] | 7.40 | 22.89 | 4.14 | |

Max. radiated noise at 1 m [dB] | in air | 54.49 | 78.40 | 70.80 |

in water (URN) | 132.22 | 159.66 | 140.35 |

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**MDPI and ACS Style**

Park, J.-H.; Lee, T.-W.; Jeong, Y.-H.; Hong, D.-K.
Novel Multi-Physics Computational Simulation of a 10 kW Permanent Magnet Motor for Podded Propulsion. *Energies* **2022**, *15*, 6607.
https://doi.org/10.3390/en15186607

**AMA Style**

Park J-H, Lee T-W, Jeong Y-H, Hong D-K.
Novel Multi-Physics Computational Simulation of a 10 kW Permanent Magnet Motor for Podded Propulsion. *Energies*. 2022; 15(18):6607.
https://doi.org/10.3390/en15186607

**Chicago/Turabian Style**

Park, Jang-Hyun, Tae-Woo Lee, Yeon-Ho Jeong, and Do-Kwan Hong.
2022. "Novel Multi-Physics Computational Simulation of a 10 kW Permanent Magnet Motor for Podded Propulsion" *Energies* 15, no. 18: 6607.
https://doi.org/10.3390/en15186607