IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 21, NO. 4, DECEMBER 2006 855 Adaptive Self-Tuning Speed Control for Permanent-Magnet Synchronous Motor Drive With Dead Time Yasser Abdel-Rady Ibrahim Mohamed, Member, IEEE Abstract—In this paper, an adaptive self-tuning speed control for a permanent-magnet synchronous motor (PMSM) drive with dead time is proposed. Firstly, to equivalently place the dead time element outside the closed-loop speed control, a dead time com- pensator (DTC), based on the Smith predictor and a self-tuning proportional-integral model-following controller (ST-PI-MFC) is proposed. The model-following error is used to adaptively update the gains of the ST-PI-MFC via the affine projection algorithm (APA). Secondly, a disturbance observer, based on the time delay control (TDC) approach is used for torque feed forward control. The system’s model is greatly simplified when the disturbance ob- server is combined with the motor. Relying on the simplified model, a natural adaptive observer is used to estimate the motor speed. Unknown motor parameters are estimated by minimizing the state estimation error using an iterative gradient algorithm offered by the affine projection. The estimated parameters are used to update the gains of the integral-proportional (IP) servo loop con- troller, the disturbance observer and the Smith model. The validity and usefulness of the proposed control scheme are verified through simulation and experimental results. Index Terms—Adaptive control, dead time, permanent-magnet synchronous motor. NOMENCLATURE APA Affine projection algorithm. DTC Dead time compensator. IP Integral-proportional. MFC Model-following controller. PI Proportional-integral. PMSM Permanent-magnet synchronous motor. ST Self-tuning. TDC Time-delay control. I. INTRODUCTION H IGH-PERFORMANCE drive systems are essential in many applications in the field of mechatronics such as robotics, computer numerically controlled (CNC) machine tools, elevators and other applications in a variety of automated industrial plants. In such applications, the motion controller may need to respond relatively swiftly to command changes and to offer enough robustness against the uncertainties of the Manuscript received October 27, 2004; revised February 26, 2005. Paper no. TEC-00306-2004. The author is with the Aircraft Electric Network Laboratory, Aerospace Re- search Center, Cairo, Egypt. He is also with the Department of Electrical and Computer Engineering, University of Waterloo, ON N2L 3G1, Canada (e-mail: yasser rady@ieee.org). Digital Object Identifier 10.1109/TEC.2005.853739 drive system [1]. Among ac and dc drives, PMSM has re- ceived widespread appeal in motion control applications. The complicated coupled nonlinear dynamic performance of PMSM can be significantly improved using vector control theory [2] where torque and flux can be controlled separately. Under perfect field orientation and with constant flux operation, a simple linear relation can characterize the torque production in the motor when the magnetic circuit is linear. However, the control performance of PMSM drive is still influenced by uncertainties, which usually are composed of unpredictable plant parameter variations, external load distur- bances, and unmodeled and nonlinear dynamics of the plant. The ways to achieve robustness against load torque disturbance and parameter variations include: robust control [3], variable struc- ture control [4], nonlinear control [5], model-reference adaptive control [6], adaptive self-tuning control [7], and other modern control theories. However, an inherent system dead time might exist in a practical drive system. The presence of system dead time reduces the closed-loop stability, particularly when high feedback gains are used. Moreover, the abovementioned design techniques and other conventional control algorithms cannot be directly applied to a plant with a dominant dead time, especially when the dead time and other plant parameters are unknown and vary with time. A DTC using the Smith predictor [8], [9] is an effective method to control a plant with a known and fixed dead time, however, its control performance is sensitive to mismatch- ing errors between the plant model and the plant dynamics, especially to dead time. In [10]–[11], a robust controller based on torque feed-forward control and a DTC is proposed. The DTC is based on the Smith predictor and a fixed-gain PI-MFC. How- ever, the control parameters are fixed, and for an unpredicted change in drive parameters, stability is not verifiably guaranteed. To guarantee stable and robust performance of a PMSM drive with dead time, under different operating conditions, a self- tuning approach is proposed in this work. Self-tuning control is a powerful adaptive control technique, which is based on an adaptive estimation algorithm. Recently, the APA [12] has been developed as a powerful estimation algorithm that offers less computational complexity than the recursive least squares (RLS), and the Kalman filter algorithms and faster convergence than the normalized least-mean-square (NLMS) algorithm. In this paper, an adaptive self-tuning control for a PMSM drive with dead time is proposed. First, to equivalently place the dead time element outside the closed-loop speed control, a DTC based on the Smith predictor and a ST-PI-MFC is proposed. The model-following error is used to adaptively update the gains of 0885-8969/$20.00 © 2006 IEEE