Abstract— This paper presents experimental study whose objective is to show the dynamic performance of a variable gain PI controller (VGPI). Indeed, the PI, although very popular and mainly used in industry, present overshoots in the tracking trajectory mode. This major disadvantage can be eliminated by maintaining the traditional PI structure and introducing the variable proportional and integrator gains. The proposed regulator is used as speed control organ in vector control to an induction motor. The practical implementation is done on a hardware experimental platform equipped with a dSpace-DSP 1104 with Matlab-Simulink-DSpace system and Control-Desk software plugged in a standard personnel computer. The various tests demonstrate the great ability of the controller to remove the overshoots and also a precise trajectory tracking. I. INTRODUCTION The induction machine associated with a static converter is a variable speed drive system whose industrial use is increasing important. This interest was partly because of its characteristics: low cost, easy maintenance and mechanical robustness. The vector control theory is nowadays mature and is usually applied in controlled drives systems with induction machines where high dynamic speed or position control performances are required [1]. In the classical structure of vector control by rotor flux orientation, PI regulators are used for controlling the rotor speed, rotor flux and the two-phase stator currents. These organs are characterized by a simple design and easy tuning of its parameters, which justifies its use in many applications [2]. However, the PI controllers have problems to remove the overshoots in the tracking trajectory mode and load disturbance rejection at the same time. This problem is had to the fact that the controller parameters are constant, hence the idea of designing a variable gain regulator to resolve this tradeoff. A (VGPI) controller is a generalization of a classical PI controller where the proportional and integrator gains vary along a tuning curve [3]. Some authors have chosen to solve this problem with modern approaches such as intelligent controllers based on A. Mechernene is with Electrical and Electronic Department, University Abou-Bekr Belkaïd, Tlemcen, Algeria, (corresponding author: e-mail: mechernene_aek@hotmail.com). L. Chrifi-Alaoui is with Laboratory of Innovative Technology, University of Picardie Jules Verne, France, (e-mail: larbi.alaoui@u- picardie.fr). M. Zerikat and N. Benharir are with Electrical Engineering Department, ENP of Oran, Algeria. (e-mails: mokhtar.zerikat@enset-oran.dz; benharir@yahoo.fr). H. Benderradji, Electrical and Engineering Department, University Mohamed Boudiaf, M’sila, Algeria, (e-mail: H_benderradji@yahoo.fr). Fuzzy Logic [4], [5] and Artificial Neural Networks [6], [7], or with non-linear approaches such as Sliding Mode [8], or Backstepping Control [9], ... But these solutions are complex and not appreciated by the industrials. In this work, a variable gain PI regulator is proposed to replace the conventional PI regulator for controlling the speed of an induction motor. In order to show the behavior and performance of the proposed controller, some experimental tests were performed in real time after implementing the control algorithm on a testing platform equipped with a hardware environment dSpace DSP-1104. The paper is organized as follows: the dynamical model of induction motor and the principle of direct field oriented control are presented in section 2. In Section 3, the structure of the VGPI controller and tuning of its parameters are described. In section 4, experimental results are presented and the obtained performance of the VGPI controllers PI and conventional fixed-gain are discussed and compared. Finally, in section 5, we give some comments and conclusions. II. INDUCTION MOTOR MODEL A. Dynamic model of Induction Motor in (d-q) reference frame The induction motor can be described by an equivalent two-phase mathematical model established in an arbitrary synchronously rotating reference frame (d-q) as [10]: . . . . . . sd sd sd s sq rd r rq r s di v K i i K dt T L           (1) . . . . . . sq sq s sd sq r rd rq r s di v K i i K dt T L           (2)   1 . . . rd m sd rd s r rq r r d L i dt T T          (3)   1 . . . rq m sq s r rd rq r r d L i dt T T          (4) , K,  and T r are positive constants defined as: 2 2 . . . . . . s r m m s s r s r R RL L K L LL LL        2 =1- . m r r s r r L L T LL R   VGPI Controller for High Performance Speed Tracking of Induction Motor Drive A. Mechernene, L. Chrifi Alaoui, M. Zerikat, N. Benharir and Hadda Benderradji Proceedings of the 3rd International Conference on Systems and Control, Algiers, Algeria, October 29-31, 2013 WeAB.5 978-1-4799-0275-0/13/$31.00 ©2013 IEEE