MOTOR CONTROLLER AND METHOD FOR CONTROLLING MOTOR

摘要

A motor controller includes an evaluation value calculator and an evaluation value searcher. The evaluation value calculator calculates an evaluation value represented by a function including a q-axis current value of a torque current component of a current through an induction motor. The evaluation value has a first sign among a positive sign and a negative sign when a rotational speed of the induction motor is greater than a frequency of a voltage applied to the induction motor by a predetermined amount, and has a second sign when the rotational speed is smaller than the frequency by the predetermined amount. The evaluation value searcher performs an evaluation value search to increase or decrease the frequency based on whether the evaluation value has the positive or negative sign so as to make the frequency close to the rotational speed of the induction motor in a free run state.

主权项

1. A motor controller comprising:
an evaluation value calculator configured to calculate an evaluation value represented by a function comprising a q-axis current value of a torque current component of a current through an induction motor, the evaluation value having a first sign among a positive sign and a negative sign when a rotational speed of the induction motor is greater than a frequency of a voltage applied to the induction motor by a predetermined amount, the evaluation value having a second sign different from the first sign among the positive sign and the negative sign when the rotational speed is smaller than the frequency by the predetermined amount; and an evaluation value searcher configured to perform an evaluation value search to increase or decrease the frequency based on whether the evaluation value has the positive sign or the negative sign so as to make the frequency close to the rotational speed of the induction motor in a free run state.