Patent ID: 8866427

Claim:
A motor control apparatus for controlling speed of a motor on the basis of a speed command value and a feedback speed value, comprising: a motor rotation-indicative quantity detection means for detecting rotation-indicative quantity of the motor at predetermined intervals, a counting means for counting the number of times that the motor rotation-indicative quantity detection means has detected the rotation-indicative quantity of the motor, a measurement interval determination means for determining whether the number of times counted by the counting means has exceeded a measurement interval or not, a speed calculation means for calculating a feedback speed value when the measurement interval determination means determines that the number of times counted has exceeded the measurement interval, the speed calculation means calculating the feedback speed value from a rotation-indicative quantity detected by the motor rotation-indicative quantity detection means immediately before, a motor rotation-indicative quantity detected by the motor rotation-indicative quantity detection means immediately before the last time the measurement interval determination means determined that the number of times counted had exceeded the measurement interval, and time that has elapsed since the last time the measurement interval determination means determined that the number of times counted had exceeded the measurement interval, and a measurement interval calculation means for setting the measurement interval for the measurement interval determination means to refer to, the measurement interval calculation means: (i) comparing the feedback speed value calculated by the speed calculation means and a speed command value to determine which is greater, (ii) calculating a first length for the measurement interval when the feedback speed value is greater than the speed command value, (iii) calculating a second length, which is less than the first length, for the measurement interval when the speed command value is greater than the feedback speed value, and (iv) setting the measurement interval to have the calculated first length or the calculated second length.