A Sensorless Commutation Error Correction Method for High-speed BLDC Motors Based on Phase Current Integration

ABSTRACT:

 Inaccurate commutation in brushless dc motor (BLDCM) will induce current harmonic and increase motor loss, which reduce motor efficiency. Meanwhile, for the sensorless BLDCM, the motor commutation is seriously affected by detection errors and calculation errors, which are caused by the nonideal conditions and the parameters variation. In this paper, a novel commutation error correction method is proposed to determine optimal commutation instant for the sensorless high-speed BLDCM. First, the relationship between commutation error and motor phase current is analyzed. According to this relationship, an initial commutation error can be calculated and compensated in one conduction interval. Then, on-line commutation corrections are  performed to compensate for the residual error in following conduction intervals. The correction accuracy of commutation instant is determined by the phase current integral difference. This method is insensitive to motor parameters and back electromotive force (BEMF) waveform. Therefore, the commutation error is effectively eliminated in the whole speed range. Finally, the feasibility and effectiveness of the proposed method are evaluated by experimental results.

KEYWORDS:

1.      Brushless dc motor

2.      High-speed

3.      Commutation error

4.      Phase current

5.      On-line optimizing

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

It is analyzed that the changes of phase voltage and phase current are caused by commutation error in BLDCM. Based on the above analysis and analytical expressions, a novel commutation error correction method is proposed. The proposed method has three characteristics as follow. 1) It decomposes the correction process into step-by-step compensation. Through the initial estimation of commutation error, the speed of correction is greatly improved for more accurate determining optimal commutation instant. The proposed method has good real-time performance without complicated parameters identification algorithms. 2) The rolling process is not sensitive for motor parameters and BEMF waveform. The variable width hysteresis controller implements an optimal control between correction accuracy and correction speed. From the experiment results, it can be shown that commutation error is effectively eliminated in the low-speed range and high-speed range. 3)  Besides, the current sensor exists in the motor speed-current control loop and it does not add new sensor. So the system reliability is improved and the cost is reduced

 

REFERENCES:

[1] T. Chun, Q. Tran, H. Lee, and H. Kim, “Sensorless control of BLDC motor drive for an automotive fuel pump using a hysteresis comparator,” IEEE Trans. Power Electron, vol. 29, no. 3, pp. 1382- 1391, Mar. 2014.

[2] Kai Liu , Ming Yin , Wei Hua , Ziqi Ma , Mingyao Lin , Yong Kong, “Design and Optimization of an External Rotor Ironless BLDCM Used in a Flywheel Energy Storage System,” IEEE Trans. Magnetics, vol.54, pp:2797 – 2801, Nov. 2018.

[3] Shaohua Chen, Gang Liu, Shiqiang Zheng, “Sensorless Control of BLDCM Drive for a High-Speed Maglev Blower Using Low Pass Filter,” IEEE Trans. Power Electron, vol. 32, no. 11, pp. 8845-8856, Nov. 2017.

[4] Christof Zwyssig, Simon D. Round, Johann W. Kolar, “An Ultrahigh- Speed, Low Power Electrical Drive System,” IEEE Trans. Industrial Electron, vol. 55, no. 2, Feb. 2008

[5] P. Alaeinovin, S. Chiniforoosh, and J. Jatskevich, “Evaluating misalignment of Hall sensors in brushless dc motors,” in Proc. IEEE Electron. Power Energy Conf. (EPEC), pp. 1–6, 2008.