CPC H02P 3/18 (2013.01) [H02P 21/18 (2016.02); H02P 21/22 (2016.02)] | 4 Claims |
1. A controller for an electric motor comprising:
a torque controller configured to calculate a torque command value by using a difference between a rotational speed of the electric motor and a rotational speed command value;
a first converter configured to convert the torque command value into a d-axis current command value and a q-axis current command value;
a second converter configured to convert a current flowing in the electric motor into a d-axis current and a q-axis current by using a position of a rotor of the electric motor;
a current controller configured to calculate a d-axis voltage command value such that a difference between the d-axis current and the d-axis current command value is reduced, and calculate a q-axis voltage command value such that a difference between the q-axis current and the q-axis current command value is reduced;
an estimator configured to estimate the position by using the d-axis current, the q-axis current, the d-axis voltage command value, and the q-axis voltage command value from which a noise is removed by a filter having a first time constant when the torque command value is equal to or greater than zero, and estimate the rotational speed and the position by using the d-axis current, the q-axis current, the d-axis voltage command value, and the q-axis voltage command value from which the noise is removed by the filter, which has a second time constant smaller than the first time constant when the torque command value is less than zero;
a third converter configured to convert the d-axis voltage command value and the q-axis voltage command value into voltage command values respectively corresponding to phases of the electric motor by using the position; and
a drive circuit configured to drive the electric motor by a result of a comparison between a carrier wave and the voltage command values respectively corresponding to the phases of the electric motor.
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