Rotating machinery controller

A rotating machinery controller for controlling a rotation-related physical quantity of a rotating machinery by operating switching devices of an inverter to supply electric power to the rotating machinery, the rotating machinery controller comprising:

• rectangular wave control means for controlling an output torque of the rotating machinery toward a desired torque by operating the switching devices such that an on-state and an off-state occur one time for one cycle period in electrical angle of the rotating machinery;
• instantaneous current value control means for, in order to control an actual current of the rotating machinery within a predetermined hysteresis region which is determined by a command current to the rotating machinery, operating the switching devices on the basis of a magnitude relation between upper and lower limits of the hysteresis region and the actual current, wherein the instantaneous current value control means operates the switching devices based on the magnitude relation between the upper and lower limits of the hysteresis region determined by the command current and the actual current of the rotating machinery, so as to feedback-control the actual current of the rotating machinery toward a current required to generate the desired torque;
• switching means for, when a current flowing through the rotating machinery deviates from the hysteresis region while the control by the rectangular wave control means is undertaken, switching the control by the rectangular wave control means to the control by the instantaneous current value control means;
• setting means for setting the command current to be a large-amplitude command current which is the same in period as, and larger in amplitude than, the required current;
• intersection estimation means for estimating an intersection time at which the large-amplitude command current intersects the required current;
• forcing means for, if at the intersection time, the operation state of the switching devices has not been changed by the instantaneous current value control means, forcibly changing the operation state of the switching devices and
• inhibiting means for inhibiting the change in operation state of the switching devices by the instantaneous current value control means from occurring for a predetermined period of time after the forced changing by the forcing means has taken place.