# Sensorless Control Strategy of a Permanent Magnet Synchronous Motor Based on an Improved Sliding Mode Observer

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## Abstract

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## 1. Introduction

## 2. Analysis of the SPMSM Sensorless Control System

## 3. Analysis of Traditional SMO

#### 3.1. Traditional SMO Observer Design

#### 3.2. Traditional SMO Control Simulation Analysis

## 4. New and Improved SMO Control Strategy

#### 4.1. Improvement of Switching Function

#### 4.2. Filter Improvements

## 5. System Simulation Result Analysis

## 6. Experimental Verification

## 7. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**Block diagram of sensor-less control of the surface mounted permanent magnet synchronous motor based on improved SMO.

**Figure 3.**SMO Comparison diagram of the motor rotor position of the traditional SMO observer at high speed.

**Figure 15.**The variation curve of the rotor position estimation error of the traditional SMO at low speed.

**Figure 16.**Variation curve of the rotor position estimation error of the new improved SMO at low speed.

**Figure 17.**The variation curve of the estimated value of two opposite electromotive forces at low speed of the traditional SMO.

**Figure 18.**The curve of the estimated value of the two opposite electromotive forces of the new and improved SMO at low speed.

**Figure 22.**Comparison of motor speed and rotor position with the traditional SMO observer at 50 rad/s.

**Figure 23.**The comparison chart of the motor speed and rotor position of the new and improved SMO observer at 50 rad/s.

**Figure 24.**The comparison chart of the motor speed and rotor position of the new and improved SMO observer at 100 rad/s.

**Figure 25.**The comparison chart of the motor speed and rotor position of the new and improved SMO observer at 200 rad/s.

Parameter | Unit | Value |
---|---|---|

Stator resistance | $R/\mathsf{\Omega}$ | 2.875 |

Flux linkage | $\Psi /Wb$ | 0.175 |

Moment of inertia | $\mathrm{J}/\mathrm{kg}\xb7{\mathrm{m}}^{2}$ | 0.001 |

Number of pole pairs | ${P}_{n}$ | 4 |

Stator inductance | ${\mathrm{L}}_{\mathrm{s}}/\mathrm{mH}$ | 8.5 |

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**MDPI and ACS Style**

Gao, W.; Zhang, G.; Hang, M.; Cheng, S.; Li, P.
Sensorless Control Strategy of a Permanent Magnet Synchronous Motor Based on an Improved Sliding Mode Observer. *World Electr. Veh. J.* **2021**, *12*, 74.
https://doi.org/10.3390/wevj12020074

**AMA Style**

Gao W, Zhang G, Hang M, Cheng S, Li P.
Sensorless Control Strategy of a Permanent Magnet Synchronous Motor Based on an Improved Sliding Mode Observer. *World Electric Vehicle Journal*. 2021; 12(2):74.
https://doi.org/10.3390/wevj12020074

**Chicago/Turabian Style**

Gao, Wengen, Gang Zhang, Mengxun Hang, Sirui Cheng, and Pengfei Li.
2021. "Sensorless Control Strategy of a Permanent Magnet Synchronous Motor Based on an Improved Sliding Mode Observer" *World Electric Vehicle Journal* 12, no. 2: 74.
https://doi.org/10.3390/wevj12020074