DSP Power Electronics IC Design DSP Control Lab

國立交通大學電力電子晶片設計與DSP控制實驗室 Power Electronics IC Design & DSP Control Lab. , NCTU, Taiwan http: //powerlab. cn. nctu. edu. tw/ J. S. Kim and S. K. Sul, “New Approach for High-Performance PMSM Drives without Rotational Position Sensors, ” IEEE Trans. Power Electron. , vol. 12, no. 5, pp. 904 -911, Sep. 1997. Sensorless PMSM Drives 賴逸軒 國立交通大學 電機與控制 程研究所 2004年 10月13日 電力電子晶片設計與DSP控制實驗室 Power Electronics IC Design & DSP Control Lab. POWERLAB NCTU 台灣新竹交通大學 • 電機與控制 程研究所 Filename: PMSM-01：Hall-Sensor Control【論文選讀翻譯】1997. New approach for high-performance sensorless PMSM drives (插圖). ppt page 1

Power Electronics IC Design and DSP Control Lab. , NCTU, Taiwan New Approach for High-Performance PMSM Drives without Rotational Position Sensors IEEE Trans. Power Electron. , vol. 12, no. 5, pp. 904 -911, Sep. 1997. 電力電子晶片設計與DSP控制實驗室 Power Electronics IC Design & DSP Control Lab. 國立交通大學 • 電機與控制 程研究所 page 2

Fig. 1. Space-vector diagram of the PMSM B Phase Equivalent 2 -phase motor model S Model on the synchronous reference frame A Phase N C Phase The exact actual rotor angle Δθr is NOT available in the drives without position sensors!!! The estimation angle Δθe in adopted. page 3

Fig. 2. Timing diagram of the electrical steady-State operation The main idea of Electrical Steady-State operation concept is to remove the current dynamics within certain period to find out the back-EMF information. Estimation Interval (n = 1) Estimation Speed Sampling Control Current Sampling k=1 i*[n] 2 3 (n = 2) Estimation Speed Control 12 k=1 i*[2] i*[1] Current 0 0 Time page 4

Fig. 3. Back-EMF constant compensator Idea: The long-term average value of actual rotor speed in steady state. has the same value as the PI (setting) (estimation) page 5

Fig. 4. Overall control structure of the proposed sensorless algorithm L. F. Compensator L. F. 0 Hz 1 50 Hz 2 Eq. (17) 1 Speed Controller 200 2 L. F. 20 Hz Z 1 Current Controller (PI+SVPWM) page 6

Fig. 5. Experimental system setup PMSM Dynamo meter Vdc IGBT inverter Ib Ia TMS 320 C 30 DSP Controller Oscilloscope page 7

Fig. 6. Angle-estimation performance of the proposed scheme The d-axis current is not perfect zero because of the nonlinearity of the control scheme: the control angel is fixed to constant value in one estimation interval while the actual rotor angle slightly moves during that period. page 8

Fig. 7. Step response of the proposed scheme 1. The machine is initially running at constant speed of 50 rpm under full load condition. 2. The speed command is changed instantaneously from 50 rpm to 2000 rpm and back to 50. page 9

Fig. 8. Speed-reversing response of the proposed PMSM sensorless drives High-Speed Case Low-Speed Case page 10

Fig. 9. Starting capability of the proposed algorithm different initial angular difference § If the initial angular difference is less than electrical 80°, the stable starting performance can be obtained in the case of half-load condition. § If the load tends to increase according to the machine speed, a special start-up algorithm is not necessary. § When the machine is under full-load condition at a standstill, the initial rotor angel should be detected through certain algorithm for stable starting. page 11

Fig. 10. Parameter dependency Ls is detuned to 50% Rs is detuned to 50% As described, the angle estimation is not affected by the parameter uncertainties. However, in the case of the detuned resistance, steady-state error of about 100 rpm occurs in the loaded operating condition with 1000 rpm reference. Small speed estimation error due to slight in accuracy of the parameter can be automatically neutralized by action of the back-EMF constant compensator. page 12

Fig. 11. Back-EMF compensation performance Compensation ON When the compensating action starts at 1 sec. This error in gradually removed by the proposed algorithm and the actual speed follows the speed command accurately after several seconds. page 13