A modified single-current-regulator control scheme for deep flux-weakening operation of interior permanent magnet synchronous motors

摘要

Traditionally, current vector controlled interior permanent magnet synchronous motors use two independent current regulators for flux-weakening operation. A novel flux-weakening control scheme which uses a single current regulator has been proposed recently. This paper compares the flux-weakening performance of an interior permanent magnet synchronous motor while running with the control schemes based on single-current-regulator and traditional two-current-regulator. As the characteristic current of the interior permanent magnet synchronous motor is less than the rated current, maximum torque per voltage control is included in both single- and two-current-regulator control schemes for deep flux-weakening operation. It was observed that the existing single-current-regulator based method does not deliver satisfactory performance at higher speeds due to the q-axis voltage limitation. Therefore, this paper proposes a modified single-current-regulator control scheme which is specifically useful in controlling interior permanent magnet synchronous motors with characteristic current less than the rated current. The experimental results prove that the proposed method can improve the flux-weakening speed range of the motor.