Field-weakening method for v/f -controlled hoist drive

This paper presents a field-weakening control method for V/f-controlled hoist drives. The method is based on the power limitation, which enables a load-dependent maximum speed without load measurement. In order to avoid the pull-out point of the hoist motor, the acceleration is halted if the motor input power exceeds a predefined limit. In addition, an integral (I) controller is used to reduce the steady-state error of the power limiter. The advantage of the proposed method is that a load sensor is not needed. Simulation and experimental results show that power limitation is suitable field-weakening method for V/f-controlled hoist drives.