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					An Accurate Automatic Phase Advance
 Adjustment of Brushless DC Motor
 IEEE TRANSACTIONS ON MAGNETICS, VOL. 45,
 NO. 1,p.120~126,JANUARY 2009
 Chun-Lung Chiu, Yie-Tone Chen, Yu-Hsiang Shen, and Ruey-Hsun Liang




        Adviser : Ming-Shyan Wang

        Student :Yu-Ming Liao
                  Outline
   Abstract
   Introduction
   Theoretical analysis
   System setup
   Experimental results
   Conclusion
   References
                           Abstract
   For improved efficiency and torque performance, brushless DC
    (BLDC) motors require a phase advance circuit.

   Performance curves of phase advance angle versus frequency for
    a conventional circuit do not work well when the harmonic
    components are considered.

   We therefore propose an improved circuit in which the phase
    advance angle is more accurate than that of a conventional circuit
    when the harmonic components are considered.
                   Introduction(1/3)
   The phase advance concept has been proposed to increase the
    efficiency of the motor in former research works[1]–[4].

   The purpose of phase advance is to let the current climb first
    before the corresponding back electromotive force (EMF) goes
    into the smooth field.

   As for the methods to realize the phase advance, the hardware
    circuit or software of single chip can be used to achieve the
    purpose.
                    Introduction(2/3)
   In the general application in
    industry, the direct phase
    advance method is usually
    used to put the Hall sensor at
    a leading position to obtain
    better performance while the
    rotor runs at high speed.
   However, it will cause a start-
    up problem if the Hall sensor
    is put too far in advance, and
    the Hall sensor only can be
    put at a fixed position.
                    Introduction(3/3)
   For the conventional phase
    advance circuit shown in Fig. 2,
    it only considers the
    fundamental sinusoidal
    component in the analysis of
    phase lead [2], [3].
   The phase advance angle of a
    conventional circuit is not
    satisfactory, so an improved
    circuit is proposed in this
    paper.
             Theoretical analysis(1/9)
   The difference between H
    and H  phases of the induced
    signal of Hall sensor in Fig. 2
    is 180 , as shown in Fig. 3.
   Then, the induced signal of the
    Hall sensor can be further
    approximated as a standard
    symmetric trapezoidal wave as
    shown in Fig. 4.
             Theoretical analysis(2/9)
   To obtain the exact analysis
    for this trapezoidal wave, the
    method of Fourier series is
    used.
           Theoretical analysis(3/9)
                                                       n=1
0.6                                                    n=3
                                                       n=5
                                                       n=7
                                                       n=9
0.4                                                    n=11




0.2
                  Theoretical analysis
  0




-0.2




-0.4




-0.6


       0   0.01   0.02       0.03        0.04   0.05
                         Theoretical analysis(4/9)
0.6                                            Fifth   0.6                                       Eleventh
0.4                                                    0.4




0.2                                                    0.2




  0                                                      0




-0.2                                                   -0.2




-0.4                                                   -0.4




-0.6                                                   -0.6


       0   0.01   0.02    0.03   0.04   0.05                  0   0.01   0.02   0.03   0.04     0.05




0.6                                      Fifteenth     0.6                                    Twenty-first
0.4                                                    0.4




0.2                                                    0.2




  0                                                      0




-0.2                                                   -0.2




-0.4                                                   -0.4




-0.6                                                   -0.6


       0   0.01   0.02    0.03   0.04   0.05                  0   0.01   0.02   0.03   0.04     0.05
             Theoretical analysis(5/9)
   The transfer function of the                R
    conventional phase advance                  1
                                         R1 //     R
    circuit can be derived as                  sC1
    presented in (2).
             Theoretical analysis(6/9)
   The phase advance angle of
    conventional circuit does not
    work well when the harmonic
    component response is
    considered.
             Theoretical analysis(7/9)
   So an improved circuit as                     1
                                           R3 //       R4
                                                 sC 3
    shown in Fig. 6 is proposed in
                                            1            1
    this paper.                      R2 //       R3 //       R4
                                           sC 2         sC 3
   The transfer function of this
    improved circuit can be
    proved as (3).
              Theoretical analysis(8/9)
   After the Fourier series in
    Table I are substituted into
    (3) to calculate the solution,
    the phase advance angle of
    the proposed circuit can be
    obtained as shown in the
    curve of Fig. 7.
             Theoretical analysis(9/9)
   The output waveform
    becomes undiscerning when
    the phase advance circuit is
    used; so the commutative
    phase point will be hard to
    decide.
   In Figs. 8 and 9, the
    comparators are used to
    generate a rectangular
    waveform in order to decide
    the more correct
    commutative phase point.
System setup
            Experimental results(1/7)
   A single-phase BLDC motor with outer rotor of four poles is used
    for the experiments and the related Hall sensor type is HW300B.
Experimental results(2/7)
Experimental waveforms of the conventional circuit
Experimental results(3/7)
Experimental waveforms of the proposed circuit
Experimental results(4/7)
          n=120*f/P
          n:轉速
          f:頻率
          P:極數
          3000(rpm)=120*100(Hz)/4


          計算超前角度
          T          260s
              360         360  9.36
          T             1
                      100Hz
            Experimental results(5/7)
   The theoretical analysis and experimental results are compared to
    each other, and the problem which the phase advance angle of the
    conventional circuit does not work well is solved now.
             Experimental results(6/7)
   For the same output power,
    the proportion of the reduced
    power consumption by the
    proposed method to the input
    power consumption of the
    conventional circuit is shown
    in Fig. 19.
   It explains the advantage with
    the proposed circuit. Because
    the phase advance angle of
    the conventional circuit is
    already over 6 deg in 1000
    rpm, its efficiency is therefore
    the worst in this speed.
            Experimental results(7/7)
   The current waveforms have been improved at 1000 rpm and
    5000 rpm but are similarly the same at 3000 rpm. It is due to the
    reason that the phase angles are nearly equal at 3000 rpm for the
    direct phase advance and proposed circuits.
                         Conclusion
   The phase advance angle of the conventional circuit is found not
    to work well when the harmonic components are also considered.
   An improved phase advance circuit has been proposed in this
    paper.
   In 33.33 Hz–166.67 Hz, the phase advance angle of the proposed
    circuit can climb around to 12.38 deg , but the conventional
    circuit climbs only to 3.89 deg when the harmonic component
    analysis is conducted for both circuits.
   The proposed circuit still appears its attraction when compared
    with the results using the direct phase advance method.
                             References(1/2)
   [1] S.-I. Park, T.-S. Kim, S.-C. Ahn, and D.-S. Hyun, “An improved current control method for
    torque improvement of high-speed BLDC motor,” in Proc. IEEE APEC, 2003, pp. 294–299.
   [2] C. M. Chao, C. P. Liao, D. R. Huang, and T. F. Ying, “A new automatic phase adjustment of
    optical drive signal,” IEEE Trans. Magn., vol. 34, no. 2, pp. 417–419, Mar. 1998.
   [3] D. R. Huang, C. Y. Fan, S. J.Wang, H. P. Pan, T. F. Ying, C. M. Chao, and E. G. Lean, “A new
    type single-phase spindle motor for HDD and DVD,” IEEE Trans. Magn., vol. 35, pp. 839–844,
    Mar. 1999.
   [4] A. Lelkes and M. Bufe, “BLDC motor for fan application with automatically optimized
    commutation angle,” in IEEE Power Electronics Specialists Conf., Aug. 2004, pp. 2277–2281.
   [5] A. Karwath, M. Moini, and E. Wunsch, “Driver circuit for brushless DC motors,” U.S. Patent 5
    583 404, Dec. 1996.
   [6] A. Karwath, M. Moini, and E. Wunsch, “Driver circuit for brushless DC motors,” U.S. Patent 5
    717 297, Feb. 1998.
   [7] A. Karwath, M. Moini, and E. Wunsch, “Driver circuit for brushless DC motors,” U.S. Patent 6
    384 554 B1, May 2002.
                              References(2/2)
   [8] A. Karwath, M. Moini, and E. Wunsch, “Driver circuit for brushless DC motors,” U.S. Patent 7
    067 998 B2, Jun. 2006.
   [9] R. Carlson, M. Lajoie-Mazenc, and J. C. dos S. Fagundes, “Analysis of torque ripple due to
    phase commutation in brushless dc machines,” IEEE Trans. Ind. Appl., vol. 28, no. 3, pp. 632–638,
    May/Jun. 1992.
   [10] B.-H. Kang, C.-J. Kim, H.-S. Mok, and G.-H. Choe, “Analysis of torque ripple in BLDC motor
    with commutation time,” in IEEE Industrial Electronic Conf., Jun. 2001, vol. 2, pp. 1044–1048.
   [11] H. Zeroug, B. Boukais, and H. Sahraoui, “Analysis of torque ripple in a BDCM,” IEEE Trans.
    Magn., vol. 38, no. 1, pp. 1293–1296, Mar. 2002.
   [12] C.-L. Chiu, Y.-T. Chen, and W.-S. Jhang, “Properties of cogging torque, starting torque, and
    electrical circuits for the single-phase brushless DC motor,” IEEE Trans. Magn., vol. 44, no. 10, pp.
    2317–2323, Oct. 2008.
   [13] J. Ni, L.Wu, B. Zhang, W. Jin, and J. Ying, “A novel adaptive commutation angle method for
    single phase BLDC motor,” in IEEE ICEMS Int. Conf., Oct. 2007, pp. 446–449.
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