# Improvement on Flux Weakening Control Strategy for Electric Vehicle Applications

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## Abstract

**:**

## 1. Introduction

## 2. PM Vector Control Equations

## 3. Flux Weakening Implementation

## 4. Traditional Flux Weakening Control Scheme in Vehicle Applications

## 5. Optimized Control Strategy for Flux Weakening Operation

## 6. Experimental Setup and Performance Comparison

## 7. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Conflicts of Interest

## Abbreviations

IPM | Interior Permanent-Magnet |

MTPA | Maximum Torque Per Ampere |

FW | Flux Weakening |

MTPV | Maximum Torque per Volt |

PM | Permanent-Magnet |

B-EMF | Back—ElectroMotive Force |

FF | Feed Forward |

LUT | Look-Up Tables |

DPS | Digital Signal Processor |

FOC | Field Oriented Control |

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**Figure 3.**Current vector position at high-speed operations where: 1. motor operating region, 2. generator operating region.

**Figure 5.**Traditional FW control scheme proposed in [17] based on outer voltage.

**Figure 6.**Feed forward results under two different battery voltage estimation. Red line actual battery voltage, blue line voltage underestimated of 5%.

**Figure 9.**Experimental results of Jahns’ control [16]. Angular mechanical speed profile (blue solid line) and $d-q$ currents signals: ${i}_{sd}$ setpoint (yellow solid line), motor ${i}_{sd}$ (light blue solid line), ${i}_{sq}$ setpoint (orange solid line) and motor ${i}_{sq}$ (grey solid line).

**Figure 10.**Experimental results of outer voltage control [17]. Angular mechanical speed profile (blue solid line) and $d-q$ currents signals: ${i}_{sd}$ setpoint (yellow solid line), motor ${i}_{sd}$ (light blue solid line), ${i}_{sq}$ setpoint (orange solid line) and motor ${i}_{sq}$ (grey solid line).

**Figure 11.**Experimental results of outer voltage control [17]. Current angle (orange solid line) and angular mechanical speed (blue solid line).

**Figure 12.**Experimental results of Jahns’ control [16]. Current angle (orange solid line) and angular mechanical speed (blue solid line).

**Figure 13.**Control scheme of outer voltage method of [17] with the proposed ${i}_{sd-safe}$ strategy.

**Figure 14.**Experimental results of outer voltage method of [17] with proposed FW control. Speed profile and ${i}_{sd},{i}_{sq}$ currents.

**Figure 15.**Experimental results of outer voltage method of [17] with proposed FW control: current angle (orange solid line) and angular mechanical speed (blue solid line).

**Figure 17.**Experimental results of the improved Jahns’ control scheme [16]: speed profile and ${i}_{d}$, ${i}_{q}$ currents signals.

**Figure 19.**Comparison between the basic FF method and the proposed ones. FF (red line), enhanced outer voltage (blue line) and enhanced Jahns’ method (black line). Experimental results.

Description | Value | Unit of Measure |
---|---|---|

Motor External Diameter | 140 | mm |

Motor Stack Length | 120 | mm |

Motor Nominal Current | 160 | mm |

Motor Nominal Torque | 15.8 | Nm |

Motor base speed | 3000 | rpm |

Motor Phase Resistance | 1.65 | m$\Omega $ |

Motor Direct axis Inductance | 0.055 | mH |

Motor Quadrature axis Inductance | 0.075 | mH |

Motor Permanent magnet flux Linkage | 0.0128 | Wb |

System Moment of inertia | 3 | kgm${}^{2}$ |

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**MDPI and ACS Style**

Bianchini, C.; Franceschini, G.; Torreggiani, A.
Improvement on Flux Weakening Control Strategy for Electric Vehicle Applications. *Appl. Sci.* **2021**, *11*, 2422.
https://doi.org/10.3390/app11052422

**AMA Style**

Bianchini C, Franceschini G, Torreggiani A.
Improvement on Flux Weakening Control Strategy for Electric Vehicle Applications. *Applied Sciences*. 2021; 11(5):2422.
https://doi.org/10.3390/app11052422

**Chicago/Turabian Style**

Bianchini, Claudio, Giovanni Franceschini, and Ambra Torreggiani.
2021. "Improvement on Flux Weakening Control Strategy for Electric Vehicle Applications" *Applied Sciences* 11, no. 5: 2422.
https://doi.org/10.3390/app11052422