Variable speed drive system of interior permanent magnet synchronous motors for constant power operation

Interior permanent magnet synchronous (IPM) motors can be applied to applications requiring constant power operation by means of the flux weakening control. The current vector control algorithm of IPM motors for constant power operation over the base speed is proposed. As the available voltage controlling the armature current vector is small in the flux weakening constant power region, the current vector sometimes becomes uncontrollable in transient operations because of the current regulator saturation. The high performance current regulator is also proposed to improve the current responses in the flux weakening region, which includes the decoupling current controller and the voltage command compensator. The control performances are confirmed by several drive tests with respect to the prototype IPM motor.<>