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Robot and Servo Drive Lab. Sinusoidal Current Drive System of Permanent Magnet Synchronous Motor with Low Resolution Position Sensor Shigeo Morimoto, Masayulu Sanada, Yoji Takeda Osaka Prefecture University 1-1 Gakuen-cho, Sakai, Osaka 593 JAPAN Adviser:Ming-Shyan Wang Student:Wei-Cheng Huang Student ID:MA020107 Department of Electrical Engineering Southern Taiwan University 2016/7/14 Outline 1.Abstract 2.Introduction 3.PM Motor Drive System 4.Principle of Position Estimation 5.Error of Estimated Position 6.Experimental results 7.Conclusions 8.References 2016/7/14 2 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Abstract The high performance drives of the sinusoidal back-EMF type permanent magnet synchronous motor can be achieved by the current vector control, where the sinusoidal currents flow according to the rotor position and the current phase is suitably controlled according to the operating condition. In such high performance drive system, a high resolution position sensor is desired. In this paper, a sinusoidal current drive system with a low resolution position sensor is proposed. The steady-state and transient characteristics are examined by the several experiments, then it is confirmed that the sinusoidal current drive and the high performance current vector control can be achieved by the proposed drive system. 2016/7/14 3 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Introduction This paper proposes a sinusoidal current drive system of the sinusoidal-wave PM motor using a low resolution position sensor, which has accuracy of only 60 electrical degrees. The proposed system will have advantage of the low-cost and the simple composition compared with the drive system with a high resolution sensor and the problems included in the sensorless system will be solved. The high resolution position information, which has enough resolution to produce the sinusoidal current commands and achieve a high-performance current vector control, is obtained by the proposed position estimating circuit. 2016/7/14 4 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. PM Motor Drive System * I The commanded value of an amplitude of phase current I * P * P The phase shifting angle are generated from the current vector controller. * The electrical angle c is calculated as c = r + by the digital adder. * i I sin r * * u p * iv I p sin r * * * 2 3 (1) 2016/7/14 5 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. PM Motor Drive System 2016/7/14 6 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Principle of Position Estimation Fig. 3 shows the block diagram of the proposed position estimating circuit, which consists of all digital ICs. Fig. 4 shows the time chart of the signals in Fig. 3. The signals M and P H represent the signals from the low resolution position sensor. 360 electrical degress Hall sensor period(60 electrical degress) clear clk C ( f /K ) 1/K 1 2 c n1 counter1 Latch c clk C (f clk counter2 n2 comparator ) clear clk P clear counter3 clk counter4 n3 n4 2016/7/14 Fig. 3 Block diagram of the proposed position estimating circuit 7 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Principle of Position Estimation 360 electrical degress counter4 counter1 clk:hall sensor counter value : n4 0 clk: f / K ( H ) counted value : n1 1 2 3 4 60 electrical degress 5 6 Z c N1(K) 0 N1(K+1) 1 0 Latch counter2 clk: f ( H ) counted value : n2 c counter3 2016/7/14 Z clk: P counted value : n3 N1(K-1) 1 2 N1(K) 1 2 N1(K) 0 0 0 0 1 0 Fig. 4 Time chart of the signals in Fig. 3. Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. 8 Error of Estimated Position m t Position : /3 1 At m0 ma T Time t : m0 t 1 / 2 T H (1) 0 0 The estimated position D may agree with the actual position if the motor speed is constant, where N 1 remains constant ( N 1( K 1) N 1( K ) N 1( K 1) ...) H ( 0) t 1 /3 Fig.5 Relationship between speed and position in acceleration But, the error between D and exists in accelerating or decelerating operation ( for example, ( N 1( K 1) N 1( K ) N 1( K 1)) in acceleration). The estimated position error ( D) can be derived as follows (see Fig. 5). 2016/7/14 9 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Error of Estimated Position 2 When the angular acceleration A (rad / s ) is constant, the motor speed is expressed by m 0 A t (2) m m Where m0 is an angular velocity of motor at t=0 If the actual rotor position (electrical) is zero at t=0, is given by (t ) Pn mdt Pn ( m 0 t t 0 1 2 2 At) (3) P n is a number of pole pairs From(3), t 1 and t 1 are given by 1 t 1 A m0 2 m0 2 3P A n (4) 1 t1 A m0 2016/7/14 2 m0 2 3P A n (5) 10 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Error of Estimated Position As the estimated position D , is given based on the average speed ma of the last period T H ( 1) (: t 0 ~ t1) , D is expressed by (t ) Pn madt Pn ma t t D 0 The average speed which is given bv 1 A t 2 ma m0 m0 (6) corresponds to the instantaneous speed at t t 1 / 2 , 1 (7) 2016/7/14 11 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Error of Estimated Position From(4),(6)and(7), 1 D (t ) 2 Pn m0 D is given by 2 m 0 3 2 P A n t (8) The estimated position error ( ) becomes maximum at t t1 in the period of T H (0) because the estimated position D is adjusted to the actual position by the signal PH D Therefore, the maximum value of the estimated position error (t1) D (t1) From (3), (5) and (8), 1 P n m 0 3 2 max 2 m 0 3 2 P A n 1 A m 0 2016/7/14 max is given by 2 m0 2 3P A n (9) 12 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Error of Estimated Position 2016/7/14 13 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Experimental results 2016/7/14 14 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Experimental results 2016/7/14 15 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Experimental results 2016/7/14 16 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Experimental results 2016/7/14 17 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Experimental results 2016/7/14 18 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Experimental results 2016/7/14 19 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Conclusions In this paper, a sinusoidal current drive system of sinusoidal-wave PM motor with low resolution position sensor has been proposed. The high resolution position information is obtained by the position estimating circuit from the low resolution position signal having the accuracy of only 60 electrical degrees. From the experimental results, it has been confirmed that the proposed drive system can achieve the sinusoidal current drive and the high performance current vector control similarly to the general drive system with a high resolution position sensor except for the accelerating and decelerating operation in low speed range. 2016/7/14 20 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. References [l] T. M. Jahns, “Flux-weakening regime operation of an interior permanent-magnet synchronous motor drive,“ ZEEE Trans. Znd. [2] S. Morimoto, K. Hatanaka, Y. Tong, Y. Takeda and T. Hirasa, “Servo Drive System and Control Characteristics of Salient Pole Permanent Magnet Synchronous Motor,“ IEEE Trans. Znd. Appl., vol. 29, pp. 338-343, MarchiApril 1993. [3] S. Morimoto, M. Sanada and Y. Takeda, “Effects and compensation of magnetic saturation in Flux-Weakening Controlled Permanent Magnet Synchronous Motor Drives,” IEEE Trans. Ind. Appl., vol. 30, pp. 1632-1637, Nov./Dec. 1994. [4] S. Ogasawara and H. Akagi, “An Approach to Position Sensorless Drive for Brushless dc Motors,” ZEEE Trans. Ind. Appl., vol. 27, pp. 928-933, Sep./Oct. 1991. [5] R. Wu and G. R. Slemon, “A Permanent Magnet Motor Drive Without a Shaft Sensor,” IEEE Trans. Ind. Appl., vol. 27, pp. 1005-1011, Sep./Oct. 1991. [6] A. B. Kulkarni and M. Ehsani, “A Novel Position Sensor Elimination Technique for the Interior Permanent-Magnet Synchronous Motor Drive,”ZEEE Trans. Ind. Appl., vol. 28, pp. 144150, Jan./Feb. 1992. [7] N. Matsui and T. Takeshita, “A Novel Starting Method of Sensorless Salient-Pole Brushless Moror,” Proc. I994 IEEE ZASAnn. Meet., pp. 386-392, 1994. [8] S. Kondo, A. Takahashi and T. Nishida, “Armature Current Locus Based Estimation Method of Rotor Position of Permanent Magnet Synchronous Motor without Mechanical Sensor,” Proc. 1995 IEEEZASAnn. Meet., pp. 55-60, 1995. Appl., vol. 23, pp. 681-689, JUly/Aug. 1987. 2016/7/14 21 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab. Thanks for your listening! 2016/7/14 22 Department of Electrical Engineering Southern Taiwan University Robot and Servo Drive Lab.