Flux-weakening control of constant power of stator-doubly-fed doubly salient motor for electric vehicles

The stator-doubly-fed doubly salient (SDFDS) motor for electric vehicles rotates with constant torque below basic speed, whereas with constant power by weakening flux over basic speed. The EMF of SDFDS motor can be controlled for the constant power control by the flux-weakening in theory as the controllable of flux. But the nonlinear characteristics of SDFDS motor cause the EMF to be anomalous square-wave. It is difficult to control the field current by the close-loop of the EMF as DC motor. In this paper, the flux-weakening control method with the feed back of armature resistance voltage is presented at the operation of constant power in order to obtain the maximal output of the SDFDS motor and extend the speed range. Simulation and experimental results confirm the theory of the flux-weakening method.