# Design and Analysis of Partitioned-Stator Switched-Flux Dual-Excitation Machine for Hybrid Electric Vehicles

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## Abstract

**:**

## 1. Introduction

- High efficiency
- High power and torque densities
- High controllability
- Wide operating range
- Maintenance-free

## 2. Partitioned-Stator Machines

## 3. Principle of Operations

_{peak}are the corresponding armature currents and the maximum value of the armature currents, respectively.

## 4. Numerical Approach

_{s}is sum of the cross-sectional area of conductor. The final equation set is the motion equation as:

_{m}is moment of inertia, ω is operating speed, T

_{L}is load torque, and λ is damping coefficient. To analyze the machine performances, a well-defined finite element method (FEM) software is employed. With the iterative approaches, the optimization of the key machine parameters can be achieved. To make a fair comparison, the key machine parameters, namely outer-stator outside diameters, airgap lengths, stack lengths, winding fill factors, and current densities are set as equal. Consequently, all three proposed machines can be compared quantitatively in a fair environment. The Prius HEV machine is also included for illustration purposes, while their key design data is listed in Table 1.

## 5. Machine Performance Analysis

#### 5.1. Machine Performance at No-Load Conditions

#### 5.2. Torque Performance Analysis

_{DC}= 0 A/mm

^{2}, I

_{DC}= −15 A/mm

^{2}, and I

_{DC}= −30 A/mm

^{2}, are about 351 Nm, 309 Nm, and 293 Nm, respectively.

_{ripple}can be calculated based on the following relationship:

_{avg}, T

_{max}, and T

_{min}are the average, maximum, and minimum torque values, respectively. It is shown that the torque pulsation of the PS-SFPM machine is about 5.3%. The torque pulsation of the FA-PS-SFPM machine under corresponding situations are about 6.2%, 9.8%, and 13.4%, while those of the PS-SFDE machine are about 6.1%, 9.6%, and 12.8%.

#### 5.3. Flux-Weakening Performance Analysis

_{DC}= −30 A/mm

^{2}, the PS-SFDE machine can only weaken its no-load EMF values by about 18%. As a result, it can be shown that the proposed FA-PS-SFPM machine can provide greater flux-weakening capability than the PS-SFDE machine does.

## 6. Evaluations on Key Criteria

## 7. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**Proposed machines: (

**a**) The partitioned-stator switched-flux permanent-magnet (PS-SFPM); (

**b**) flux adjuster (FA)-PS-SFPM; (

**c**) partitioned-stator switched-flux dual-excitation (PS-SFDE). PM–permanent magnet.

**Figure 2.**Field paths of PS-SFPM machine, (

**a**) Rotor on right hand side; (

**b**) rotor on left hand side. Figures are modified with permission from [19], published by IEEE, 2017.

**Figure 4.**Flux-weakening principles: (

**a**) FA-PS-SFPM; (

**b**) PS-SFDE. Figures are modified with permission from [19], published by IEEE, 2017.

**Figure 6.**Flux-linkages (Red: phase-A, blue: phase-B and black: phase-C): (

**a**) PS-SFPM; (

**b**) FA-PS-SFPM; (

**c**) PS-SFDE.

**Table 1.**Major Machine Parameters, machine dimensions are reproduced from [19].

Item | Prius | PS-SFPM | FA-PS-SFPM | PS-SFDE |
---|---|---|---|---|

Outer-stator outside diameter (mm) | 269 | 269 | 269 | 269 |

Outer-stator inside diameter (mm) | 161.9 | 194.9 | 194.9 | 194.9 |

Rotor outside diameter (mm) | 160.4 | 193.4 | 193.4 | 193.4 |

Rotor inside diameter (mm) | 110.6 | 155.9 | 155.9 | 155.9 |

Inner-stator outside diameter (mm) | N/A | 154.4 | 154.4 | 154.4 |

Inner-stator inside diameter (mm) | N/A | 110 | 80 | 80 |

Airgap length (mm) | 0.7 | 0.7 | 0.7 | 0.7 |

Stack length (mm) | 84 | 84 | 84 | 84 |

Number of stator slots | 48 | 12 | 12 | 12 |

Number of rotor poles | 8 | 13 | 13 | 13 |

Number of phases | 3 | 3 | 3 | 3 |

Number of armature turns | 13 | 33 | 33 | 18 |

**Table 2.**Key Machine Performance Comparisons, data of Prius are reproduced from [19].

Item | Prius | PS-SFPM | FA-PS-SFPM | PS-SFDE |
---|---|---|---|---|

Efficiency (%) | 86 | 88 | 87 | 87 |

Power (W) | 46,200 | 48,000 | 47,000 | 44,000 |

Base speed (rpm) | 1200 | 1200 | 1200 | 1200 |

Output torque (Nm) | 368 | 385 | 376 | 351 |

Torque ripple (%) | 20.7 | 5.3 | 6.2 | 6.1 |

Cogging torque (Nm) | N/A | 16.2 | 14.5 | 13.8 |

Total mass (kg) | 32.9 | 31.6 | 32.5 | 32.1 |

Power density (W/kg) | 1404 | 1519 | 1446 | 1370 |

Torque density (Nm/kg) | 11.2 | 12.2 | 11.6 | 10.9 |

Material cost (USD) | 95.4 | 119.1 | 121.3 | 126.2 |

Power/cost (W/USD) | 484 | 403 | 387 | 349 |

Torque/cost (Nm/USD) | 3.9 | 3.2 | 3.1 | 2.8 |

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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**MDPI and ACS Style**

Lee, C.H.T.; Chau, K.T.; Ching, T.W.; Chan, C.C.
Design and Analysis of Partitioned-Stator Switched-Flux Dual-Excitation Machine for Hybrid Electric Vehicles. *World Electr. Veh. J.* **2018**, *9*, 40.
https://doi.org/10.3390/wevj9030040

**AMA Style**

Lee CHT, Chau KT, Ching TW, Chan CC.
Design and Analysis of Partitioned-Stator Switched-Flux Dual-Excitation Machine for Hybrid Electric Vehicles. *World Electric Vehicle Journal*. 2018; 9(3):40.
https://doi.org/10.3390/wevj9030040

**Chicago/Turabian Style**

Lee, Christopher Ho Tin, Kwok Tong Chau, Tze Wood Ching, and Ching Chuen Chan.
2018. "Design and Analysis of Partitioned-Stator Switched-Flux Dual-Excitation Machine for Hybrid Electric Vehicles" *World Electric Vehicle Journal* 9, no. 3: 40.
https://doi.org/10.3390/wevj9030040