| Title |
Identification of Motor Parameters and Improvement of Voltage Error for Improvement of Back-emf Estimation in Sensorless Control of Low Speed Operation |
| Authors |
김경훈(Kyung-Hoon Kim) ; 윤철(Chul Yun) ; 조내수(Nae-Soo Cho) ; 장민호(Min-Ho Jang) ; 권우현(Woo-Hyen Kwon) |
| DOI |
http://doi.org/10.5370/KIEE.2018.67.5.635 |
| Keywords |
Permanent magnet synchronous motor ; Motor parameter identification ; Voltage error ; Sensorless control ; 2-point calculation |
| Abstract |
This paper propose a method to identify the motor parameters and improve input voltage error which affect the low speed position error of the back-emf(back electromotive force) based sensorless algorithm and to secure the operation reliability and stability even in the case where the load fluctuation is severe and the start and low speed operation frequently occurs. In the model-based observer used in this paper, stator resistance, inductance, and input voltage are particularly influential factors on low speed performance. Stator resistance can cause resistance value fluctuation which may occur in mass production process, and fluctuation of resistance value due to heat generated during operation. The inductance is influenced by the fluctuation due to the manufacturing dispersion and at a low speed where the change of the current is severe. In order to find stator resistance and inductance which have different initial values ??and fluctuate during operation and have a large influence on sensorless performance at low speed, they are commonly measured through 2-point calculation method by 2-step align current injection. The effect of voltage error is minimized by offsetting the voltage error. In addition, when the command voltage is used, it is difficult to estimate the back-emf due to the relatively large distortion voltage due to the dead time and the voltage drop of the power device. In this paper, we propose a simple circuit and method to detect the voltage by measuring the PWM(Pulse Width Modulation) pulse width and compensate the voltage drop of the power device with the table, thereby minimizing the position error due to the exact estimation of the back-emf at low speed. The suitability of the proposed algorithm is verified through experiment. |