Robust Control of Encoderless Synchronous Reluctance Motor Drives Based on Adaptive Backstepping and Input-Output Feedback Linearization Techniques

Document Type : Research Article


1 Jafar Soltani is with the Faculty of Engineering, Islamic Azad University, Khomeini-shahr Branch, Esfahan, Iran (e-mail:

2 Corresponding Author, Hossein Abootorabi Zarchi is with the Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran (e-mail:


In this paper, the design and implementation of adaptive speed controller for a sensorless synchronous reluctance motor (SynRM) drive system is proposed. A combination of well-known adaptive input-output feedback linearization (AIOFL) and adaptive backstepping (ABS) techniques are used for speed tracking control of SynRM. The AIOFL controller is capable of estimating motor two-axis inductances (Ld, Lq), simultaneously. The overall stability of the proposed control and Persistency of Excitation (PE) condition are proved based on Lyapunov theory. In the proposed control drive system, the maximum torque control (MTC) scheme and constant current in inductive axis control (CCIAC) are applied to generate the motor d and q axis reference currents which are needed for the AIOFL controller. In addition, an ABS speed controller is designed to compensate for the machine parameter uncertainties and load torque disturbances. Another contribution of this paper is to estimate the rotor speed and position in very low speed by using 1) a simple technique for eliminating the voltage sensors, 2) a simple method for online estimation of the stator resistance, and 3) modeling the voltage drop of the inverter power switches. Finally, the validity and capability of the proposed method are verified through simulation and experimental studies.


[1]     R. Morales Caporal and M. Pacas, “A Predictive Torque Control for the Synchronous Reluctance Machine taking into account the magnetic cross saturation”, IEEE Trans. On Ind. Electronics, vol. 54, No. 2, pp. 1161-1167, Apr. 2007.
[2]     T. H. Liu and H. H. Hsu, “Adaptive Controller Design for a Synchronous Reluctance Motor Drive System with Direct Torque Control”, IET Electric Power Appl., vol. 1, No.5, pp. 815–824 815, 2007.
[3]     H.F. Hofmann, S.R. Sanders, and A. EL-Antably, “Stator-flux-oriented vector control of synchronous reluctance Machines with maximized efficiency”, IEEE Trans. On Industrial Electronics, vol. 51, Issue 5, pp. 1066-1072, Oct. 2004.
[4]     H. D. Lee, S. J. Kang, and S. K. Sul, “Efficiency-Optimized DTC of Synchronous Reluctance Motor using Feedback Linearization”, IEEE Trans. On Ind. Elec., vol.46, No.1, pp. 192-198, 1999.
[5]     P. Guglielmi, M. Pastorelli and A. Vagati, ”Impact of cross-saturation in sensorless control of transverse-laminated synchronous reluctance motors”, IEEE Trans. On Ind. Elect., vol. 53, Issue 2, , pp. 429-439, 2006.
[6]     A. Vagati, M. Pastorelli, and G. Franceschini, “High-performance control of synchronous reluctance motors”, IEEE Trans. on Industry Appl., vol. 33,  Issue 4,  July-Aug. 1997, .  pp. 983-991, 2004.
[7]     E. M. Rashad, T. S. Radwan, and M. A. Rahman, “A MTPA Vector Control Strategy for Synchronous Reluctance Motors Considering Saturation and Iron Losses”,  IEEE IAS, pp. 2411-2417, 2005.
[8]     M. G. Jovanovic, and R. E. Betz, “Optimal Torque Controller for Synchronous Reluctance Motors”, IEEE Transactions on Energy Conversion, vol. 14, No. 4, pp. 1088-1093, December 1999.
[9]     R. E. Betz, R. Lagerquist, and M. Jovanovic, "Control of Synchronous Reluctance Machies", IEEE Trans. On Industry Application, vol. 29, No. 6, pp. 1110-1122, Nov. 1993.
[10]  S. Ichikawa, M. Tomita, S. Doki, and S. Okuma, "Sensorless Control of Synchronous Reluctance Motors Based on Extended EMF Models Considering Magnetic Saturation with Online Parameter Identification", IEEE Trans. On Industry Applications, vol. 42, No. 5, pp. 1264-1274, Sept./Oct. 2006.
[11]  R. Marino, and P. Tomei, Nonlinear Control Design, Prentice Hall, Inc, 1995.
[12]  R. Morales Caporal and M. Pacas, “Encoderless Predictive DTC for SynRM at Very Low and Zero Speed”, IEEE Trans. Ind. Elect., vol. 55, No. 12, pp. 4408-4416, Dec. 2008.
[13]  C. A. M. D. Ferraz, and C. R. de Souza, ''Considering Iron Losses in Modeling the Reluctance Synchronous Motor'', 7th International workshop on Advance Motion Control (AMC), pp. 251-256, July 2002. 
[14]  H. Abootorabi Zarchi, J. Soltani and Gh. R. Arab Markadeh, ''Adaptive IOFL Based Torque Control of SynRM without Mechanical Sensor'', IEEE Trans. On Industrial Electronics, vol. 57, No. 1, pp. 375-384, January 2010.
[15]  H. Abootorabi Zarchi, Gh. R. Arab Markadeh, and J. Soltani, ''Direct torque and flux regulation of synchronous reluctance motor drives based on input–output feedback linearization'', Elsevier  Journal, Energy Conversion and Management , vol. 51, pp. 71–80, January 2010. 
[16]  H. Abootorabi Zarchi, Gh. R. Arab Markadeh, and J. Soltani, ''Direct Torque Control of  Synchronous Reluctance Motor using Feedback Linearization Including Saturation  and Iron Losses', European Power Electronics and Drives (EPE) Journal, vol. 19,No.3, pp. 50-62, September 2009.
[17]   L. Tang, and M. F Rahman, “Investigation of an Improved Flux Estimator of a Direct Torque Controlled Interior Permanent Magnet Synchronous Machine Drive”, 35th Annual IEEE Power Electronics Specialists Conf., Aachen, Germany, pp. 451-457, 2004.
[18]  S. Mir, M.E Elbuluk, and D.S. Zinger, “PI and Fuzzy Estimators for Tuning the Stator Resistance in Indirect Torque Control of Induction Machines”, IEEE Tran. On Power Electronics, vol. 13, No. 2, pp. 279-287, March 1998.
[19]  R. E. Betz, ''Theoretical Aspects of the Control of Synchronous Reluctance Machines'', IEE Proceeding B, vol. 139, No. 4, pp. 355-364, July 1992.
[20]  R. E. Betz, and T. J. E., Miller, ''Aspects of the Control of Synchronous Reluctance Machines", Proceedings European Power Elect. Conf., pp. 456-463, EPE 1991. 
[21]  A. Chiba, and T. Fukao, ''A Closed-loop Operation of Super High-Speed Reluctance Motor for Quick Torque Response'', IEEE Trans. On Industry Applications, vol. 28, No. 3, pp. 600-606, 1992.
[22]  T. A. Lipo, ''Synchronous Reluctance Machines- A viable alternative for ac drives'', Electric Machines and Power Systems, vol. 19, pp. 659-671, 1991.
[23]  J. Holtz, and J. Quan, “Drift- and Parameter-Compensated Flux Estimator for Persistent Zero-Stator-Frequency Operation of Sensorless-Controlled Induction Motors”, IEEE Trans. On Ind. Appl., vol. 39, No. 4, pp. 1052-1060 , July/Aug. 2003.
[24]  V. d. Broeck, H. C. Skudelny, and G. V. Stanke, “Analysis and Realization of a Pulse Width Modulator Based on Voltage Space Vectors”, IEEE Trans. On Ind. Appl., vol. 24, No. 11, pp. 142-150, 1988.
[25]  J. Holtz, “Sensorless Control of Induction Machines -With or Without Signal Injection?”, IEEE Trans. On Ind. Elect. , vol.  53, No. 1, pp. 7-30, Feb. 2006.
[26]  M. Jafarboland,  and  H. Abootorabi Zarchi,  Efficiency-Optimized Variable Structure Direct Torque Control for Synchronous Reluctance Motor Drives', Journal of Electrical Systems,  vol. 8, No. 1, pp. 95-107, 2012.