Abstract—This paper presents a comparative study on two most popular control strategies for Permanent Magnet Synchronous Motor (PMSM) drives: field-oriented control (FOC) and direct torque control (DTC). The comparison is based on various criteria including basic control characteristics, dynamic performance, and implementation complexity. The study is done by simulation using the Simulink Power System Blockset that allows a complete representation of the power section (inverter and PMSM) and the control system. The simulation and evaluation of both control strategies are performed using actual parameters of Permanent Magnet Synchronous Motor fed by an IGBT PWM inverter. Keywords—PMSM, FOC, DTC, hysteresis, PWM. I. INTRODUCTION ERMANENT magnet (PM) synchronous motors have attracted increasing interest in recent years for industrial drive application. The high efficiency, high steady state torque density and simple controller of the PM motor drives compared with the induction motor drives make them a good alternative in certain applications. Moreover, the availability of low-cost power electronic devices and the improvement of PM characteristics enable the use of PM motors even in some more demanding applications [1]. It is now recognized that the two high-performance control strategies for PMSM are field-oriented control (FOC) and direct torque control (DTC). They have been invented respectively in the 70’s and in the 80’s. These control strategies are different on the operation principle but their objectives are the same. They aim both to control effectively the motor torque and flux in order to force the motor to accurately track the command trajectory regardless of the machine and load parameter variation or any extraneous disturbances. Both control strategies have been successfully implemented in industrial products. The supporters of field-oriented control and direct torque control claim the superiority of their strategy versus the other. Up to now, the question has not been clearly answered. The purpose of this paper is to present a comparative study on these two control strategies in order to clarify the “myth”. The comparison is based on various criteria including basic control characteristics, static and dynamic performance, and implementation complexity [2]. II. THE MODEL OF PMSM The electrical and mechanical equations of the PMSM in the rotor reference (d-q ) frame are as follows [7]: 1 q s d d r q d d d s d q q r d f r q q q q L R d I I I V dt L L R L d I I I V dt L L L ω ω ϕω ⎧ =− + + ⎪ ⎪ ⎨ ⎪ = − − − + ⎪ ⎩ (1) f d d d I L ϕ ϕ + = (2) q q q I L = ϕ (3) And the electromagnetic torque e C is given by: )] ) [( 2 3 f q q d q d e I I I L L P C ϕ + − = (4) The equation for the motor dynamics, on the other hand, is e r f d C C C J dt Ω − − = (5) Ω = P ω (6) Fig. 1 presents the model of PMSM in d-q axis: Fig. 1 Functional schema of the Park model III. DESCRIPTION OF FIELD-ORIENTED CONTROL AND DIRECT TORQUE CONTROLS SCHEMES A. Field-Oriented Control System The primary principle in controlling a PMSM drive is based on field orientation. Since the magnetic flux generated from Comparison of Field-Oriented Control and Direct Torque Control for Permanent Magnet Synchronous Motor (PMSM) M. S. Merzoug, and F. Naceri P World Academy of Science, Engineering and Technology International Journal of Electrical and Computer Engineering Vol:2, No:9, 2008 1797 International Scholarly and Scientific Research & Innovation 2(9) 2008 scholar.waset.org/1307-6892/3658 International Science Index, Electrical and Computer Engineering Vol:2, No:9, 2008 waset.org/Publication/3658