Losses Minimization of Two Asymmetrical Windings Induction Motor Based on Swarm Intelligence A. M. A. AMIN, M. I. KORFALLY, A. A. SAYED, and O.T. M.HEGAZY Department of Power and Electrical Machines Faculty of Engineering, Helwan University Cairo, EGYPT E- Mail. amrmagic@hotmail.com Abstract In this paper, applying field orientation based on Particle Swarm Optimization (PSO) controls the speed of two- asymmetrical windings induction motor. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point. In addition, the electro- magnetic torque is also improved while maintaining a fast dynamic response. In this research, a novel approach is used to evaluate the optimal rotor flux level. This approach is based on Particle Swarm Optimization (PSO). PSO method is a member of the wide category of Swarm Intelligence methods (SI). This research presents two speed control strategies. These are field- oriented controller (FOC) and FOC based on PSO. The strategies are implemented mathematically and experimental. The simulation and experimental results have demonstrated that the FOC based on PSO method saves more energy than the conventional FOC method. Key Words: mathematical model of the two-phase induction motor; Field-Orientation; motor losses, Particle Swarm Optimization; Inverter Circuits; Loss Minimization Control; Simulation and Experimental Results. 1 Introduction The two asymmetrical windings induction motor is treated as a two-phase induction motor (TPIM). It is used in many low power applications, where three–phase supply is not readily available. This type of motor runs at an efficiency range of 50% to 65% at rated operating conditions [1]. The conventional field-oriented controller normally operates at rated flux at any values with its torque range. When the load is reduced considerably, the core losses become so high causing poor efficiency. If significant energy savings are required, it is necessary to optimize the efficiency of the motor. The optimum efficiency is obtained by the evaluation of the optimal rotor flux level [3]. This flux level is varied according to the torque and the speed of the operating point. In this paper, PSO is applied to evaluate the optimal flux. It has the straightforward goal of minimizing the total losses for a given load and speed. It is shown that the efficiency is reasonably close to optimal. 2 Mathematical Model of the Motor The d-q model of an unsymmetrical windings induction motor in a stationary reference frame can be used for a dynamic analysis. It can take core loss into account. The d-q model as applied to TPIM is described in [4], [5]. The equivalent circuit is shown in fig. 1. The machine model may be expressed by the following voltage and flux linkage equations [4]: Voltage Equations: qs qs m qs p i r v λ + = (1) ds ds a ds p i r v λ + = (2) qr dr r qr r p k i r λ λ ω + - = * ) / 1 ( 0 (3) dr qr r ds R p k i r λ λ ω + + = * 0 (4) ) ( 0 qfe qr qs mq qfe qfe i p i p i p L R i - + + - = (5) ) ( 0 dfe dr ds md dfe dfe i p i p i p L R i - + + - = (6) Flux Linkage Equations: ) ( qfe qr qs mq qs lm qs i i i L i L - + + = λ (7) ) ( dfe dr ds md ds la ds i i i L i L - + + = λ (8) r m L lm L mq L lr + - (1/k)ωrλ dr + - V qs r r i qs i qr R qfe i qfe r a L la L md L lR + - kωrλ qr + - V ds i ds i dr R dfe i dfe r R Fig. 1. The d-q axis two-phase induction motor Equivalent circuit with iron losses. ) i i i ( L i L qfe qr qs mq qr lr qr - + + = λ (9) ) i i i ( L i L dfe dr ds md dr lR dr - + + = λ (10) Electrical torque equation is expressed as: ( ) 11 ) ( 1 ) ( ( 2 qfe dr ds qr md qfe qr qs dr mq i i i i L k i i i i L k P Te - + - - + = Dynamic Equation is given as follows: r m r m l B p j T Te ω ω + = - (12) 3 Field-Oriented Controller [FOC] The stator windings of the motor are unbalanced. The machine parameters differ from the d axis to the q axis. The 1156 1-4244-0136-4/06/$20.00 '2006 IEEE