Loading field analysis on PMAC servo motor

The permanent magnet AC (PMAC) servo motor is widely used in the fields requiring the ultimately high performance. Such as good dynamics, low torque pulsation and noise, etc. Hence, how to get the assured output torque plays a dominant role in servo motor design. In PMAC servo motor using i_d = Q control strategy, the electromagnetic power is only related to current and back emf. Back emf is taken by the flux produced by PM. But, because of the armature reaction´s effect, the flux produced by PM is different from that in the open-circuit condition. In this paper, a method has been developed for separating the fields produced by PM and winding current under any specified load condition. The technique is based on a 2-dimensional finite element analysis. Then a 10-pole/9-slot PMAC servo motor´s field is analyzed using this method. This method is applicable to other PM motors.