Novel Back EMF Zero Difference Point Detection Based Sensorless Technique for BLDC Motor

ABSTRACT:

In this paper a novel position sensorless scheme named Back EMF Zero Difference Point (ZDP) detection has been proposed for six-switch VSI converter fed permanent magnet BLDC motor. This technique is based on the comparison of back EMFs and detection of the points in the back EMF waveforms where they cross each other or in other words they are equal. Commutation point is achieved exactly at the same instant when the difference of back EMFs of any two phases becomes zero. The simulation study has been carried out for the proposed sensorless scheme. The proposed sensorless scheme has the excellent performance from zero to the extra high speed. The method needs no additional delay circuit as used for calculation of commutation point from back EMF ZCP and involves less calculation burden. The method is fault tolerant and accurate even in the case of noise in measurement (or estimation) of phase back EMFs. A nonzero threshold value proportional to input voltage (or reference speed) is used for overcoming the problem due to quantization and sampling for digital implementation. This method proves to be excellent substitute of hall sensing scheme as it also senses at zero speed.

KEYWORDS:

  1. BLDC motor
  2. Back EMF ZDP
  3. Commutation
  4. Sensorless control
  5. Zero difference point.

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig.1 VSI fed BLDC motor with indirect Back EMF detection scheme

EXPECTED SIMULATION RESULTS:

Fig.2. Phase Back EMF ZDPs, switching signals, counter output and triggering sequence signals.

Fig.3. Steady state operation at the low speed of 600 rpm.

Fig.4. performance of proposed sensorless scheme at 17000 rpm

Fig.5. Noise immune performance during steady state operation for reference speed of 17000rpm.

Fig.6. sensing fault occurs at 0.5 second in the measurement of phase-B back EMF.

Fig.7. speed increases when sensing fault occurs (here phase-B sensing fault

CONCLUSION:

In the proposed Back EMF Zero Difference Point (ZDP) detection method, the very first commutation signal is achieved at starting itself i.e. one step before the ZCP method, which proves the superiority of the method. The back EMF for the proposed scheme can be applied to various existing back EMF detection or estimation techniques. This technique is insensitive to the inherent noise in measurement (or estimation) of back EMF. This method does not need extra

Circuitry as needed for delay after ZCP for getting commutation point, thereby less computational complexity is involved. The speed (or input voltage) proportional threshold used for avoiding uncertainty in the zero difference of back EMF, sets its scope of wide usability in precise operation from zero to extra high speed. Operation at initial zero back EMF is the main strength of this method and it doesn’t necessitate separate starting techniques. Speed response at transient period is 0.15 ms faster than previous methods for identical motor parameters.

REFERENCES:

[1] M.V.Kesava Rao, Department of Electrical technology, IISc Bangalore, ‘‘Brush Contact Drops in DC machines’’, Accepted 25-6-1934, Bangalore Press.

[2] Y.S. Jeon, H.S. Mok, G.H. Choe, D.K. Kim, J.S. Ryu, “A New Simulation Model of BLDC Motor with Real Back EMF waveform”, 7 th workshop on Computers in power Electronics , 2000 (COMPEL 2000), page 217- 220.

[3] Padmaja yedmale, “Brushless DC (BLDC) Motor Fundamentals”, AN885, 2003 Microchip Technology.

[4] S. Tara , Syfullah Khan Md “Simulation of sensorless operation of BLDC motor based on the zero cross detection from the line voltage” International Journal of Advanced Research in Electrical Electronics and Instrumentation Engineering, vol 2, issue 12 , December 2013, ISSN 2320-3765.

[5] J. R. Frus and B. C. Kuo, “Closed-loop control of step motors using waveform detection,” in Proc. Int. Conf. Stepping Motors and Systems, Leeds, U.K., 1976, pp. 77–84.

 

Sensorless Brushless DC Motor Drive Based on the Zero-Crossing Detection of Back Electromotive Force (EMF) From the Line Voltage Difference  

 

ABSTRACT:

This paper describes a position sensorless operation of permanent magnet brushless direct current (BLDC) motor. The position sensorless BLDC drive proposed, in this paper, is based on detection of back electromotive force (back EMF) zero crossing from the terminal voltages. The proposed method relies on a difference of line voltages measured at the terminals of the motor. It is shown, in the paper, that this difference of line voltages provides an amplified version of an appropriate back EMF at its zero crossings. The commutation signals are obtained without the motor neutral voltage. The effectiveness of the proposed method is demonstrated through simulation and experimental results.

KEYWORDS:

  1. Back electromotive force (EMF) detection
  2. Brushless dc (BLDC) motor
  3. Sensorless control
  4. Zero crossing

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of the experimental setup.

EXPECTED SIMULATION RESULTS:

 

Fig. 2. Phase current and speed waveform on no-load (experimental).

Fig. 3. Phase current and speed waveform on load (experimental).

Fig. 4. Phase current and speed waveform during loading transient (experimental).

Fig. 5. Phase current, virtual Hall, and real Hall sensor signal for 50% duty

ratio PWM switching

CONCLUSION:

A simple technique to detect back EMF zero crossings for a BLDC motor using the line voltages is proposed. It is shown that the method provides an amplified version of the back EMF. Only three motor terminal voltages need to be measured thus eliminating the need for motor neutral voltage. Running the machine in sensorless mode is then proposed, in this paper, making use of the novel zero-crossing detection algorithm. While starting relies on triggering devices at the zero crossings detected using the proposed algorithm, continuous running is achieved by realizing the correct commutation instants 30delay from the zero crossings. The motor is found to start smoothly and run sensorless even with load and load transients. Simulation and experimental results are shown which validate the suitability of the proposed method.

REFERENCES:

[1] D. O. Koval and C. Carter, “Power quality characteristics of computer loads,” IEEE Trans. on Industry Applications, vol. 33, no. 3, pp. 613- 621, May/June1997.

[2] Abraham I. Pressman, Keith Billings and Taylor Morey, “Switching Power Supply Design,” 3rd ed., McGraw Hill, New York, 2009.

[3] B. Singh, B.N. Singh, A. Chandra, K. Al-Haddad, A. Pandey and D.P. Kothari, “A review of single-phase improved power quality AC-DC converters” IEEE Trans. on Industrial Electronics, vol.50, no.5, pp.962- 981, Oct. 2003.

[4] K. Mino, H. Matsumoto, Y. Nemoto, S. Fujita, D. Kawasaki, Ryuji Yamada, and N. Tawada, “A front-end converter with high reliability and high efficiency,” in IEEE Conf. on Energy Conversion Congress and Exposition (ECCE),2010, pp. 3216-3223.

[5] Jih-Sheng Lai, D. Hurst and T. Key, Switch-mode supply power factor improvement via harmonic elimination methods,” in 6th Annual IEEE Proc. on Applied Power Electronics Conference and Exposition, APEC’91, 1991, pp. 415-422.

Unknown Input Observer for a Novel Sensorless Drive of Brushless DC Motors

 

ABSTRACT:

In this paper, a novel motor control method is proposed to improve the performance of sensorless drive of BLDC motors. In the terminal voltage sensing method, which is a great portion of sensorless control, a precise rotor position cannot be obtained when excessive input is applied to the drive during synchronous operation mode. Especially in the transient state, the response characteristic decreases. To cope with this problem, the unknown input (back-EMF) is modeled as the additional state of system in this paper. Taking into account the disturbance adopted by the back-EMF, the observer can be obtained by an equation of the augmented system. An algorithm to detect the back-EMF of a BLDC motor using the state observer is constructed. As a result, a novel sensorless drive of BLDC motors that can strictly estimate rotor position and speed is proposed.

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of BLDC motor drive

EXPECTED SIMULATION RESULTS:

Fig. 2. Speed response for the start and transient state. (a) In the proposed sensorless scheme. (b) In the conventional scheme use sensor.

Fig. 3. Simulation results of the proposed sensorless scheme at 2000 (rpm). (a) Rotor speed. (b) Rotor position. (c) Phase current. (d) Line-to-line back-EMF. (e) Commutation function. (f) Commutation signal.

Fig. 4. Simulation results of the proposed sensorless scheme at 100 (rpm). (a) Rotor speed. (b) Rotor position. (c) Phase current. (d) Line-to-line back-EMF. (e) Commutation function. (f) Commutation signal.

CONCLUSION:

In this paper, the unknown input (back-EMF) is modeled as the additional state of system. Considering disturbance that is adopted by back-EMF, the observer can be obtained effectively using the equation of augmented system and estimating back-EMF. As a result, an effective algorithm to estimate rotor position and speed of motor using the state observer is proposed. Use of sensorless control method can remove problem on manufacture that is happened in circuit to detect rotor position and speed. Moreover the production of inexpensive motor controller may be possible because the additional circuit such as encoder is not necessity. In cases using the proposed sensorless control method, the start-up performance has an almost analogous transient state characteristic after forced alignment, compared with the conventional method. This method also provides useful motor control because it is possible to analyze about transient state as well as steady state unlike various sensorless control methods that have been recently proposed. In addition, it can be easily applied in industry applications requiring the low-cost style drive of BLDC motor because actual realization is very simple.

REFERENCES:

[l] T. J. E Miller, “Brushless Permanent-Magnet and Reluctance Motor Drives,” Clarendon

Press, Oxford 1989.

[2] S. Ogasawara and H. Akagi, “An Approach to Position Sensorless Drive for Brushless DC

Motors,” IEEE Trans. Ind. Appl., vol. 27, no. 5, pp. 928-933, Sep./Oct. 1991.

[3] J. C. Moreira, “Indirect Sensing for Rotor Flux Position of Permanent Magnet AC Motors

Operating Over a Wide Speed Range,” IEEE Trans. Ind. Appl., vol. 32, no. 6, pp. 1392-1401,

Nov./Dec. 1996.

[4] H. R. Andersen and J. K. Pedersen, “Sensorless ELBERFELD Control of Brushless DC Motors for Energy-Optimized Variable-Speed Household Refrigerators,” EPE Conf. Rec., vol. 1,

  1. 314-318, Sep. 1997.

[5] Hyeong-Gee Yee, Chang-Seok Hong, Ji-Yoon Yoo, Hyeon-Gil Jang, Yeong-Don Bae and Yoon-Seo Park, “Sensorless Drive for Interior Permanent Magnet Brushless DC Motors,” Electric Machines and Drives Conf. Record, 1997, IEEE International 18-21 pp. TD1/3.1-

TD1/3.3, May 1997.

 

 

Sensorless Brushless DC Motor Drive Based on the Zero-Crossing Detection of Back Electromotive Force (EMF) From the Line Voltage Difference

ABSTRACT:

This paper describes a position sensorless operation of permanent magnet brushless direct current (BLDC) motor. The position sensorless BLDC drive proposed, in this paper, is based on detection of back electromotive force (back EMF) zero crossing from the terminal voltages. The proposed method relies on a difference of line voltages measured at the terminals of the motor. It is shown, in the paper, that this difference of line voltages provides an amplified version of an appropriate back EMF at its zero crossings. The commutation signals are obtained without the motor neutral voltage. The effectiveness of the proposed method is demonstrated through simulation and experimental results.

KEYWORDS:

  1. Back electromotive force (EMF) detection
  2. Brushless dc (BLDC) motor
  3. Sensorless control
  4. Zero crossing

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

Fig. 1. Block diagram of the experimental setup.

EXPECTED SIMULATION RESULTS:

 

Fig. 2. Phase current and speed waveform on no-load (experimental).

Fig. 3. Phase current and speed waveform on load (experimental).

Fig. 4. Phase current and speed waveform during loading transient (experimental).

Fig. 5. Phase current, virtual Hall, and real Hall sensor signal for 50% duty ratio PWM switching.

CONCLUSION:

A simple technique to detect back EMF zero crossings for a BLDC motor using the line voltages is proposed. It is shown that the method provides an amplified version of the back EMF. Only three motor terminal voltages need to be measured thus eliminating the need for motor neutral voltage. Running the machine in sensorless mode is then proposed, in this paper, making use of the novel zero-crossing detection algorithm. While starting relies on triggering devices at the zero crossings detected using the proposed algorithm, continuous running is achieved by realizing the correct commutation instants 30delay from the zero crossings. The motor is found to start smoothly and run sensorless even with load and load transients. Simulation and experimental results are shown which validate the suitability of the proposed method.

REFERENCES:

[1] K. Iizuka,H.Uzuhashi, M. Kano, T. Endo, and K.Mohri, “Microcomputer control for sensorless brushless motor,” IEEE Trans. Ind. Appl., vol. IA- 21, no. 4, pp. 595–601, May/Jun. 1985.

[2] J. Shao, D. Nolan,M. Teissier, and D. Swanson, “A novel micro controller based sensorless brushless DC (BLDC) motor drive for automotive fuel pumps,” IEEE Trans. Ind. Appl., vol. 39, no. 6, pp. 1734–1740, Nov./Dec. 2003.

[3] T.-H. Kim and M. Ehsani, “Sensorless control of BLDC motors from near-zero to high speeds,” IEEE Trans. Power Electron., vol. 19, no. 6, pp. 1635–1645, Nov. 2004.

[4] S. Ogasawara and H. Akagi, “An approach to position sensorless drive for brushless DC motors,” IEEE Trans. Ind. Appl., vol. 27, no. 5, pp. 928–933, Sep./Oct. 1991.

[5] R. C. Becerra, T. M. Jahns, and M. Ehsani, “Four-quadrant sensorless brushless ECM drive,” in Proc. IEEE APEC, Mar. 1991, pp. 202–209.

A New Approach to Sensorless Control Method for Brushless DC Motors

ABSTRACT:

This paper proposes a new position sensorless drive for brushless DC (BLDC) motors. Typical sensorless control methods such as the scheme with the back-EMF detection method show high performance only at a high speed range because the magnitude of the back-EMF is dependent upon the rotor speed. This paper presents a new solution that estimates the rotor position by using an unknown input observer over a full speed range. In the proposed method, a trapezoidal back-EMF is modelled as an unknown input and the proposed unknown input observer estimating a line-to-line back-EMF in real time makes it possible to detect the rotor position. In particular, this observer has high performance at a low speed range in that the information of a rotor position is calculated independently of the rotor speed without an additional circuit or complicated operation process. Simulations and experiments have been carried out for the verification of the proposed control scheme.

KEYWORDS:

  1. BLDC motor
  2. Full speed range
  3. Sensorless control
  4. Unknown input observer

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Overall structure of the proposed sensorless drive system.

EXPECTED SIMULATION RESULTS:

 Fig. 2. Response waveforms at under step change of load torque. (Speed reference: 50 rpm, Load: 0.2 → 0.5 Nm).

 

Fig. 3. Response waveforms under step change of load torque. (Speed reference: 1650 rpm, Load: 0.75 → 1.5 Nm).

 

Fig. 4. Response waveforms under step change of speed reference. (Load: 0.75 Nm, Speed reference: 50 → 1650 → 50 rpm).

CONCLUSION:

This paper presented a new approach to the sensorless control of the BLDC motor drives using the unknown input observer. This observer can be obtained effectively by using the equation of augmented system and an estimated line-to-line back- EMF that is modelled as an unknown input. As a result, the actual rotor position as well as the machine speed can be estimated strictly even in the transient state from the estimated line-to-line back-EMF.

The novel sensorless method using an unknown input observer can

  • be achieved without additional circuits.
  • estimate a rotor speed in real time for precise control.
  • make a precise commutation pulse even in transient state as well as in steady state.
  • detect the rotor position effectively over a full speed range, especially at a low speed range.
  • calculate commutation function with a noise insensitive.
  • be easily realized for industry application by simple control algorithm.

The simulation and experimental results successfully confirmed the validity of the developed sensorless drive technique using the commutation function.

REFERENCES:

[1] N. Matsui, “Sensorless PM brushless DC motor drives,” IEEE Trans. on Industrial Electronics, vol. 43, no. 2, pp. 300-308, 1996.

[2] K. Xin, Q. Zhan, and J. Luo, “A new simple sensorless control method for switched reluctance motor drives,” KIEE J. Electr. Eng. Technol., vol. 1, no. 1, pp. 52-57, 2006.

[3] S. Ogasawara and H. Akagi, “An approach to position sensorless drive for brushless DC motors,” IEEE Trans. on Industry Applications, vol. 27, no. 5, pp. 928-933, 1991.

[4] J. C. Moreira, “Indirect sensing for rotor flux position of permanent magnet AC motors operating over a wide speed range,” IEEE Trans. on Industry Applications, vol. 32, no. 6, pp. 1394-1401, 1996.

[5] J. X. Shen, Z. Q. Zhu, and D. Howe, “Sensorless flux-weakening control of permanent-magnet brushless machines using third harmonic back EMF,” IEEE Trans. on Industry Applications, vol. 40, no. 6, pp. 1629-1636, 2004.