Industry Application of ZeroSpeed Sensorless Control Techniques for PM Synchronous Motors

1
Industry Application of Zero-Speed Sensorless
Control Techniques for PM Synchronous Motors
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL.
37, NO. 2, MARCH/APRIL 2001
Alfio Consoli, Fellow, IEEE, Giuseppe Scarcella,
Member, IEEE, and Antonio Testa, Member, IEEE

• Student Jia-Je Tsai
• Adviser Ming-Shyan Wang
• Date 10th-Dec-2008

2
Outline

• Abstract
• I. INTRODUCTION
• II. SENSORLESS CONTROL OF PMSM DRIVES
• III. A SIMPLE SENSORLESS TECHNIQUE
• IV. ROTOR POSITION DETECTION AT STANDSTILL
• V. EXPERIMENTAL RESULTS
• VI. CONCLUSIONS
• VII. REFERENCES

3
Abstract

• This paper presents the state of the art in the
  area of industrial applications of sensorless
  control for permanent-magnet synchronous motor
  (PMSM) drives.
• Based on high-frequency signal injection, it is
  possible to achieve zero-speed operation
  without increasing the complexity and the cost of
  the system.
• The paper focuses on the practical implementation
  of one of the previously described
  high-frequency injection techniques in both
  salient and nonsalient PM machines.

4
INTRODUCTION

• PMSM drives are today gradually replacing classic
  dc drives in a large number of industrial
  applications, taking full advantage of key
  features of PM motors, such as compactness,
  efficiency, robustness, reliability, and shape
  adaptation to working environment.
• PMSM drives need a relatively expensive position
  transducer to correctly align the current vector.
• Sensorless techniques generally estimate the
  rotor position by processing electrical motor
  variables, such as phase currents or stator
  voltages.

5
INTRODUCTION

• The simplest PMSM sensorless techniques are based
  on rotor-flux-position estimation, by
  integration of the back EMF, but it fails at low
  and zero speed.
• A simple sensorless technique following such an
  approach is presented in this paper. It properly
  works at any speed, ranging from zero to the
  rated value, and can be applied to both salient
  and nonsalient machines.
• It does not require the knowledge of any motor
  parameter, while it allows low-cost
  implementation, requiring only current sensors
  already included in standard drives.

6
SENSORLESS CONTROL OF PMSM DRIVES

• By neglecting hysteresis and eddy-current losses,
  the model of a cageless interior PMSM
  (IPMSM),written in a d-q rotor reference frame,
  with the d axis aligned with the direction of the
  PM flux , as shown in Fig. 1, is

7
SENSORLESS CONTROL OF PMSM DRIVES
Fig. 1. Vector diagram of a PMSM.
8
SENSORLESS CONTROL OF PMSM DRIVES

• It is assumed that in an IPMSM owning
  a salient magnetic structure, while
  in a surface-mounted PMSM (SPMSM) owning a
  nonsalient magnetic structure.
• As it is possible to observe from (6), in a PMSM
  the torque depends on both the amplitude of the
  stator current vector and by the torque
  angle, defined as the angular displacement
  of the current vector from the d axis.

9
A SIMPLE SENSORLESS TECHNIQUE

• In this paper, a simple but effective zero-speed
  sensorless technique for PMSM drives is
  presented. Compared with other techniques based
  on high-frequency signal injection, the
  proposed sensing shows lower sensitivity to
  noise, higher resolution.
• A high-frequency stator
  voltage component and on a suitable
  demodulation of the generated stator current
  component .
• In IPMSMs a maximum of the current amplitude
  occurs when the voltage vector is aligned with
  the maximum inductance axis and a minimum occurs
  when the voltage vector is aligned with the
  minimum inductance axis.

10
A SIMPLE SENSORLESS TECHNIQUE

• Assuming an IPMSM supplied only with the 600-Hz
  additional voltage component , the mathematical
  model of the machine gives
• where
• expressed in electrical radians are
  respectively, the angular position of the d
  axis and of the additional 600-Hz voltage vector.

11
A SIMPLE SENSORLESS TECHNIQUE

• From the previous equations at zero rotor speed
  it is possible to obtain the following
  steady-state expression
• where

12
A SIMPLE SENSORLESS TECHNIQUE

• Substituting in (9) the parameters of an actual
  IPMSM, as reported in Table I.
• At frequencies higher than 400 Hz, (9) can be
  reduced to

TABLE I PMSM PARAMETERS
13
A SIMPLE SENSORLESS TECHNIQUE

• According to such an hypothesis, as shown in Fig.
  2, minimum points of occur at
  and maximum
  points at
  
• 
  
• The position of the d axis can be easily
  obtained from , which is known.
• The sampling time

Fig. 2. Proposed rotor position estimation
technique in a IPMSM
14
A SIMPLE SENSORLESS TECHNIQUE
TABLE II ROTOR POSITION SAMPLING TIME
15
A SIMPLE SENSORLESS TECHNIQUE

• has been settled to 15 V by trials,
  obtaining an experimentally evaluated efficiency
  reduction of less than 1 at rated power.

Fig. 3. Implementation of the proposed technique
16
A SIMPLE SENSORLESS TECHNIQUE

• The approximation introduced in (10) causes a
  small constant phase error
  between and

17
ROTOR POSITION DETECTION AT STANDSTILL

• According to the proposed technique, the
  estimated position shows an
  uncertainty of electric degrees.
• In order to solve such uncertainty, the rotor can
  be initially placed in a known position by
  injecting a dc current.
• A dc current pulse is injected along the d axis,
  zero torque is generated, avoiding any shaft
  motion.

18
ROTOR POSITION DETECTION AT STANDSTILL

• The injected current and the magnet flux own the
  same sign, the saturation level will
  increase, as well as the saliency and the
  amplitude of the high- frequency current
  component as the Fig. 5.

19
ROTOR POSITION DETECTION AT STANDSTILL

• Fig. 6. and 7. show the envelope of
  experimentally recorded when a current test
  signal is injected, having, respectively, the
  same and the opposite sign of the rotor flux.

20
ROTOR POSITION DETECTION AT STANDSTILL
21
EXPERIMENTAL RESULTS

• The first is based on a 0.75-kW six-pole IPMSM,
  whose parameters are reported in Table
  I. (Figs. 8-13)
• The second prototype is based on a 0.69-kW
  six-pole SPMSM, whose parameters are
  also reported in Table I.

22
EXPERIMENTAL RESULTS

• the output of a 1024-pulses-per-round encoder.

23
EXPERIMENTAL RESULTS
24
EXPERIMENTAL RESULTS
25
EXPERIMENTAL RESULTS
26
EXPERIMENTAL RESULTS
27
EXPERIMENTAL RESULTS

• According to Table II, at zero speed in Fig. 13
  we have a rotor position sampling time
  of 416 , thus allowing good accuracy.

28
EXPERIMENTAL RESULTS

• Fig. 14 shows a shaft position control test in
  which the reference is changed from 0 to 2
  rad and back to 0.

29
EXPERIMENTAL RESULTS
30
EXPERIMENTAL RESULTS
31
EXPERIMENTAL RESULTS
32
EXPERIMENTAL RESULTS
33
CONCLUSIONS

• It has been shown that the proposed technique can
  be used either in IPMSMs, owning a salient
  magnetic structure, or in SPMSMs and dc brushless
  motors, that own a nonsalient structure.
• The proposed technique features wide speed
  operating range, from zero up to the rated
  speed, wide position estimation bandwidth, that
  allows for either speed and position control, and
  good accuracy.
• Although sufficient for vector and speed control,
  the resolution obtained at the present is not
  sufficient for servo applications.
• However, no theoretical limits prevent to reach
  higher resolutions by improving the practical
  implementation of the proposed sensorless
  technique, which, in this paper, has been mainly
  oriented to low-cost applications.

34
REFERENCES

• 1 E. K. Kenneth, A. C. Liew, and T. A. Lipo,
  New observer-based DFO scheme for speed
  sensorless field-oriented drives for
  low-zero-speed operation, IEEE Trans. Power
  Electron., vol. 13, pp. 959968, Sept. 1998.
• 2 A. Consoli, A. Musumeci, S. Raciti, and A.
  Testa, Sensorless vector and speed control of
  brushless motor drive, IEEE Trans. Ind.
  Electron., vol. 41, pp. 9196, Feb. 1994.
• 3 R. Dhaouadi, N. Mohan, and L. Norum, Design
  and implementation of an extended Kalman filter
  for the state estimation of a permanent magnet
  synchronous motor, IEEE Trans. Power Electron.,
  vol. 6, pp. 491497, Sept./Oct. 1994.
• 4 M. Schroedl and T. Stefan, New rotor
  position detector for permanent magnet
  synchronous machines using the INFORM method,
  Eur. Trans. Elect. Power Eng., vol. 1, no. 1, pp.
  4753, 1991.

35
Thanks for your attention