Deep flux weakening control of a segmented interior permanent magnet synchronous motor with maximum torque per voltage control

Recent research suggest many flux weakening control techniques for interior permanent magnet synchronous motors. The most established one is the use of two current controllers to control the direct and quadrature axis current components such that the total flux linkage is reduced. If the characteristic current of the motor is less than the rated current of the system, maximum torque per voltage control should be carried out in the flux weakening operation in order to minimize the flux further for a maximum torque. In this paper, the performance of a prototype segmented interior permanent magnet synchronous motor under the flux weakening control with two current controllers are discussed. Because the motor has a characteristic current less than the rated current, maximum torque per voltage control is studied. It is observed from the experimental results that the constant power range can be improved approximately to 3:1 when the maximum torque per voltage control is used, whereas it is 2.3:1 with the conventional flux weakening operation.