Sensorless Direct Torque and Indirect Flux Control of Brushless DC Motor with Non-Sinusoidal Back-EMF

ABSTRACT:

In this paper, the position sensorless direct torque and indirect flux control (DTIFC) of BLDC motor with nonsinusoidal (non-ideal trapezoidal) back-EMF has been extensively investigated using three-phase conduction scheme with six-switch inverter. In the literature, several methods have been proposed to eliminate the low-frequency torque pulsations for BLDC motor drives such as Fourier series analysis of current waveforms and either iterative or least-mean-square minimization techniques. Most methods do not consider the stator flux linkage control, therefore possible high-speed operations are not feasible. In this work, a novel and simple approach to achieve a low-frequency torque ripple-free direct torque control with maximum efficiency based on dq reference frame similar to permanent magnet synchronous motor (PMSM) drives is presented. The electrical rotor position is estimated using winding inductance, and the stationary reference frame stator flux linkages and currents. The proposed sensorless DTC method controls the torque directly and stator flux amplitude indirectly using d–axis current. Since stator flux is controllable, flux-weakening operation is possible. Moreover, this method also permits to regulate the varying signals. Simple voltage vector selection look-up table is designed to obtain fast torque and flux control. Furthermore, to eliminate the low-frequency torque oscillations, two actual and easily available line-to-line back- EMF constants (kba and kca) according to electrical rotor position are obtained offline and converted to the dq frame equivalents using the new Line-to-Line Park Transformation. Then, they are set up in the look-up table for torque estimation. The validity and practical applications of the proposed three-phase conduction DTC of BLDC motor drive scheme are verified through simulations and experimental results.

KEYWORDS:

  1. Brushless dc (BLDC) motor
  2. Position sensorless control
  3. Direct torque control (DTC)
  4. Stator flux control
  5. Fast torque response
  6. Non-sinusoidal back-EMF
  7. Low frequency torque ripples

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

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Fig. 1. Overall block diagram of the position sensorless direct torque and indirect flux control (DTIFC) of BLDC motor drive using three-phase conduction mode.

EXPECTED SIMULATION RESULTS:

  image002                                          

Fig. 2. Simulated indirectly controlled stator flux linkage trajectory under the sensorless three-phase conduction DTC of a BLDC motor drive when  is changed from 0 A to -5 A under 0.5 N·m load torque.

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Fig. 3. Actual q– and d–axis rotor reference frame back-EMF constants versus electrical rotor position  and

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Fig.4. Steady-state and transient behavior of the experimental (a) q–axis stator current, (b) d–axis stator current, (c) estimated electromagnetic torque and (d) baca frame currents when  under 0.5 N·m load torque.

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Fig. 5. Experimental indirectly controlled stator flux linkage trajectory under the sensorless three-phase conduction DTC of a BLDC motor drive when  at 0.5 N·m load torque.

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Fig. 6. Steady-state and transient behavior of the actual and estimated electrical rotor positions from top to bottom, respectively under 0.5 N·m load torque.

CONCLUSION:

This study has successfully demonstrated application of the proposed position sensorless three-phase conduction direct torque control (DTC) scheme for BLDC motor drives. It is shown that the BLDC motor could also operate in the field weakening field weakening region by properly selecting the d–axis current reference in the proposed DTC scheme. First, practically available actual two line-to-line back-EMF constants (%”# and %$#) versus electrical rotor position are obtained using generator test and converted to the dq frame equivalents usingthe new Line-to-Line Park Transformation in which only two input variables are required. Then, they are used in the torque estimation algorithm. Electrical rotor position required in the torque estimation is obtained using winding inductance, stationary reference frame currents and stator flux linkages. Since the actual back-EMF waveforms are used in the torque estimation, low-frequency torque oscillations can be reduced convincingly compared to the one with the ideal trapezoidal waveforms having 120 electrical degree flat top. A look-up table for the three-phase voltage vector selection is designed similar to a DTC of PMSM drive to provide fast torque and flux control. Because the actual rotor flux linkage is not sinusoidal, stator flux control with constant reference is not viable anymore. Therefore, indirect stator flux control is performed by controlling the flux related d–axis current using bang-bang (hysteresis) control which provides acceptable control of time-varying signals (reference and/or feedback) quite well. Since the proposed DTC scheme does not involve any PWM strategies, PI controllers as well as inverse Park and Clarke Transformations to drive the motor, much simpler overall control is achieved.

REFERENCES:

[1] I. Takahashi and T. Noguchi, “A new quick-response and high efficiency control strategies of an induction motor,” IEEE Trans. Ind. Appl., vol. 22, no. 5, pp. 820–827, Sep./Oct. 1986.

[2] M. Depenbrock, “Direct self-control of inverter-fed induction machine,” IEEE Trans. Power Electron., vol. 3, no. 4, pp. 420–429, Oct. 1988.

[3] L. Zhong, M. F. Rahman, W. Y. Hu, and K. W. Lim, “Analysis of direct torque control in permanent magnet synchronous motor drives,” IEEE Trans. Power Electron., vol. 12, no. 3, pp. 528–536, May 1997.

[4] Y. Liu, Z. Q. Zhu, and D. Howe, “Direct torque control of brushless dc drives with reduced torque ripple,” IEEE Trans. Ind. Appl., vol. 41, no. 2, pp. 599–608, Mar./Apr. 2005.

 

[5] S. B. Ozturk and H. A. Toliyat, “Direct torque control of brushless dc motor with non-sinusoidal back-EMF,” in Proc. IEEE-IEMDC Biennial Meeting, Antalya, Turkey, May 3-5, 2007.

Sensor Less Speed Control of permanent magnet synchronous motor (PMSM) using SVPWM Technique Based on MRAS Method for Various Speed and Load Variations

ABSTRACT:

The permanent magnet synchronous motor (PMSM) has emerged as an alternative to the induction motor because of the reduced size, high torque to current ratio, higher efficiency and power factor in many applications. Space Vector Pulse Width Modulation (SVPWM) technique is applied to the PMSM to obtain speed and current responses with the variation in load. This paper analysis the structure and equations of PMSM, SVPWM and voltage space vector process. The Model Reference Adaptive System (MRAS) is also studied. The PI controller uses from estimated speed feedback for the speed senseless control of PMSM based on SVPWM with MRAS. The control scheme is simulated in the MATLAB/Simulink software environment. The simulation result shows that the speed of rotor is estimated with high precision and response is considerable fast. The whole control system is effective, feasible and simple.

KEYWORDS:

  1. PMSM
  2. Space vector pulse width modulation
  3. Model reference adaptive system

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Schematic Block of MRAS scheme                      

Fig. 1. Schematic Block of MRAS scheme

Sensor less control block diagram with MRAS system

Fig. 2. Sensor less control block diagram with MRAS system

EXPECTED SIMULATION RESULTS:

Reference and real speed of PMSM

Fig. 3. Reference and real speed of PMSM

Electromagnetic torque of PMSM

Fig. 4. Electromagnetic torque of PMSM

Reference and real speed of PMS

Fig. 5. Reference and real speed of PMS

Electromagnetic torque of PMSM

Fig. 6. Electromagnetic torque of PMSM

 Reference and real speed of PMSM

Fig. 7. Reference and real speed of PMSM

Electromagnetic torque of PMSM

Fig. 8. Electromagnetic torque of PMSM

Reference and real speed of PMSM

Fig. 9. Reference and real speed of PMSM

Electromagnetic torque of PMSM

Fig. 10. Electromagnetic torque of PMSM

CONCLUSION:

A detailed Simulink model for a PMSM drive system with SVPWM based on model reference adaptive system has being developed. Mathematical model can be easily incorporated in the simulation and the presence of numerous toll boxes and support guides simplifies the simulation. The space vector pulse width modulation technique (SVPWM) control technique is used in PMSM drive which has its potential advantages, such as lower current waveform distortion, high utilization of DC voltage, low switching and noise losses, constant switching frequency and reduced torque pulsations provides a fast response and superior dynamic performance. Matlab/Simulink based computer simulation results shows that the adaptive algorithm improve dynamic response, reduces torque ripple, and extended speed range. Although this control algorithm does not require any integration of sensed variables.

REFERENCES:

[1] Young Sam Kim, Sang Kyoon Kim, Young Ahn Kwon, “MRAS Based Sensorless vontrol of permanent magnet synchronous motor”, SICE Annual conference in Fukui, August 4-6,2003.

[2] Xiao Xi, LI Yongdong, Zhang Meng, Liang Yan, “A Sensorless Control Based on MRAS Method in Interior Pernanent-Magnet Machine Drive”, pp734-738, PEDS 2005.

[3] Zhang Bingy, Cen Xiangjun et al. “A pposition sensor less vector control system based on MRAS for low speeds and high torque PMSM drive”, Railway technology avalanche, vol.1, no.1, pp.6, 2003.

[4] P. Vas, “Sensorless Vector and Direct Torque Control”, Oxford University Press, 1988.

[5] A. K. Gupta and A. M. Khambadkone, “A Space Vector PWM Scheme for Multilevel Inverters Based on Two-Level Space Vector PWM,” IEEE Transactions on Industrial Electronics, vol. 53, no 5, pp. 1631-1639, Oct. 2006.

Mtech EEE Projects-Power Electronics and Power Systems

Electrical and Electronics Engineering (EEE)

BTech and MTech EEE projects  can be done in different domains. They are power electronics and drives,  power systems, electrical machines and drives etc. Each of these domains use many technologies and areas.

We understand the importance of IEEE papers for BTech and M.Tech EEE projects. Hence we hand pick IEEE projects for BTech and M.Tech EEE. We ensure that the IEEE papers and projects have enough scope for a two semister project work or for a final year project work. If needed an improvement over the simulated results by newer and better techniques for MTech EEE can also be done. The Matlab / Simulink software is used for doing EEE projects. We do give guidance for paper writing and suggest journals.

Research Paper Writing-MTech EEE

BTech and MTech EEE projects of various domains are available at Asoka Technologies. We also develop your own ideas. We deliver the projects within the time frame given by the students. Visit our website and blogspot for more papers.

BTECH IEEE Projects-Electrical Engineering

BTech IEEE Projects in Electrical and Electronics Engineering (EEE)

BTech IEEE projects  can be done in different domains. They are power electronics and drives,  power systems, electrical machines and drives etc. Each of these domains use many technologies and areas.

We understand the importance of IEEE papers for BTech projects. Hence we hand pick IEEE projects for BTech and M.Tech EEE. We ensure that the IEEE papers and projects have enough scope for a final year project work. The Matlab / Simulink software is used for doing EEE projects. We do give guidance for paper writing and suggest journals.

Research paper writing-BTech IEEE Projects

BTech and MTech EEE projects of various domains are available at Asoka Technologies. We also develop your own ideas. We deliver the projects within the time frame given by the students. Visit our website and blogspot for more papers.

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