Ελαχιστοποίηση απωλειών σύγχρονων κινητήρων με δρομέα έκτυπων πόλων

Abstract

The controllable electromagnetic losses in Synchronous Motor Drives (SMD) in general and in wound-field, salient pole, SMD in particular, consist of the copper losses, the iron losses and the stray losses. From the theoretical analysis and experimental verification, two loss minimization conditions are derived for the optimal values of the field current and the direct axis armature current, respectively. These values depend on the operating speed and the load torque. The proposed method is easily implemented on inverter fed, adjustable speed, motor drives. The efficiency improvement and the energy saving are considerable when the motor operates at light load. The Loss Model Control (LMC) algorithm is a real time discrete algorithm. It calculates the present value of the field current from the previous values of the direct and quadrate axis armature current. It then calculates the present value of the direct axis current from the present value of the field current and the previous value of the quadrate axis armature current. The present value of the quadrate axis armature current is then calculated from the present values of the field current and the direct axis armature current. All values are functions of the operating speed and the load conditions. The method does not take into account the variation of the machine’s parameters due to saturation (operating conditions). It considers steady state function of the machine. The proposed method is compared, using simulation, to two classical loss minimization methods. The =0 method and the maximum Torque per Ampere method. The efficiency of the motor when the proposed Loss Model Control algorithm is adopted is higher than the efficiency resulting from the other methods. Their difference increases with the operating speed and the load torque. The proposed LMC method can be applied to any wound-field, salient pole, synchronous motor drive. It can also be applied to other types of synchronous motor drives, such as the wound-field, cylindrical rotor, synchronous motor drives, the permanent magnet motor drives and the reluctance motor drives.