Abstract — In this paper a new loss minimization control algorithm for inverter-fed permanent-magnet synchronous motors (PMSM), which allows to reduce the power losses of the electric drive without penalty on its dynamic performances, is analyzed, experimentally realized and validated. In particular, after a brief recall of two loss minimization control strategies (the “search control” and the “loss-model control”), both a modified dynamic model of the PMSM, which takes into account the iron losses, and a “loss-model” control strategy, are treated. Experimental tests on a specific PMSM drive employing the proposed loss minimization algorithm were performed aiming to validate the actual implementation. The main results of these tests confirm that the dynamic performances of the drive are maintained, and enhancement up to 3.5% of the efficiency can be reached in comparison to the PMSM drive equipped with a more traditional control strategy. Index Terms —Permanent magnet synchronous motor, motor drives, variable speed drives, control systems, efficiency improvement. I.INTRODUCTION Today particular emphasis is addressed towards environmental pollution. In this respect, the link between any wasted energy and the consequent negative fall-down as increase of the environmental pollution has been well demonstrated. In particular, this applies to electrical consumption, which involves complicated industrial processes for the electric energy development. Thus long-term operations of electrical drives, which are a noticeable load- consuming equipment, like those for electric vehicle propulsion or industrial apparatuses (compressors, fans, pumps, machine tools, etc.), are expected to have high efficiency as one of the most important figures. The whole efficiency depends on the single efficiency of the different components of the electric drives. It is worth noting that by using optimal control strategies it is possible to reduce the losses of the electric drives, without loss of the dynamic performances of the drive. Permanent magnet synchronous motors (PMSMs) are widely used in industrial drive applications for their high performances. The main reasons rely on their optimal characteristics, which are, for example, higher efficiency and higher power-weight ratio than dc and induction motors. PMSMs are convenient because they have a loss-free rotor, and power losses are mainly related to the stator windings and the stator core. The ratio of the copper and iron power losses is a key issue in determining the maximum efficiency point as function of the mechanical load on the motor shaft. In the case of constant-speed motors fed by the main, the motor designer performs a trade-off in order to obtain a maximum efficiency at given load conditions, according to the user requirements. Unfortunately, this advantageous condition is no longer true as long as the motors operate at variable-torque and variable-speed. This paper deals with a control algorithm, which is able to reduce the losses (copper and iron losses) of interior permanent magnet synchronous motor drives, through an optimal management of the current space vector in the stator winding, in the case of variable speed and variable torque applications. In particular, after a brief recall of two loss minimization control strategies [1], [2], [3] (the “search control” and the “loss-model control”), both a modified dynamic model of the PMSM that takes into account also the iron losses and a “loss-model” control strategy, implemented by the authors [4] are treated. The control algorithm allows determining the optimal current space vector according to the operating speed and the load conditions. The exploited approach can be applied to machines with both salient and non-salient rotor types, but the best results are reached with the latter ones. Experimental tests on a specific PMSM drive employing the proposed loss minimization algorithm have shown that its dynamic performances are maintained, and enhancement up to 3.5% of the efficiency can be reached in comparison to the PMSM drive equipped with a more traditional control strategy (i d=0). II.LOSS MINIMIZATION CONTROL STRATEGIES Loss minimization control strategies have been extensively investigated in literature [5], [6], [7], [8], and [9]. They can fundamentally be summarized into two main categories: “loss model control” strategies and “search control” ones. The “loss model control” technique is based on the development of a mathematical model, which allows estimating the energy losses of the motor. By expressing the losses as a function of the control variables of the electrical drive, then it is possible Analysis a DSP Implementation and Experimental Validation of a Loss Minimization Algorithm Applied to Permanent Magnet Synchronous Motor Drives C. Cavallaro (*) , A. O. Di Tommaso (**) , R. Miceli (**) , A. Raciti (*) , G. Ricco Galluzzo (**) , M. Trapanese (**) (*) Dept. of Electrical, Electronic and Systems Engineering, University of Catania Viale A. Doria, 6 - 95125 Catania, Italy, Tel. +39 095 7382323 Fax +39 095 339535 E-mail: ccavalla@diees.unict.it - araciti@diees.unict.it (**) Department of Electrical Engineering, University of Palermo Viale delle Scienze - 90128 Palermo, Italy, Tel. +39 091 6615 285 Fax +39 091 488452 E-mail: ditommaso@diepa.unipa.it - miceli@diepa.unipa.it - ricco@diepa.unipa.it - trapanese@diepa.unipa.it 1