Patent ID: 8115429

Claim:
A motor control apparatus that drives a brushless motor, comprising: a current command value setting portion that sets a d-axis current command value and a q-axis current command value that are indicative of currents to be supplied to the brushless motor; a voltage command value calculating portion that calculates a d-axis voltage command value and a q-axis voltage command value that are indicative of voltages to be applied to the brushless motor in order to supply the current indicated by the d-axis current command value and the q-axis current command value to the brushless motor; a determining portion that determines whether a magnitude of a command voltage vector, formed by the d-axis voltage command value as a d-axis voltage component and the q-axis voltage command value as a q-axis voltage component, is greater than a predetermined voltage value; a voltage vector adjusting portion that adjusts the magnitude of a voltage vector that corresponds to a q-axis current and that forms the command voltage vector in order to adjust the magnitude of the command voltage vector to be equal to or less than the predetermined voltage value when the determining portion determines the magnitude of the command voltage vector is greater than the predetermined voltage value; and a current estimating portion that estimates a q-axis current estimated value based on i) a ratio of the magnitude of the voltage vector after adjustment divided by the magnitude of the voltage vector before adjustment, and ii) the q-axis current command value.