| Abstract |
A simple method to enlarge the operation limit of a field-weakening speed control system for a self-controlled synchronous motor is proposed. It is shown that in the case of a constant set value for the de input
current limiter the angle of overlap of armature currents increases greatly when speed reference is increased, and maximum allowable change in speed reference is restricted to a relatively small value. A variable current limiter, in which the set value for the de input current limiter is changed in such a way that it is proportional to the field
current of the motor, is useful for limiting an excessive increase in the angle of overlap in transients, and it is shown that the change in speed reference without commutation failure can be widened greatly with this limiter, The effects of magnetic saturation on the steady-state speed region in which commutation failure does not occur during transients are also clarified. |
