Patent ID: 7911168

Claim:
A device for controlling a motor, comprising: a control unit that controls a drive signal for determining a voltage to be supplied to the motor; and a drive unit that drives the motor by applying a current corresponding to the voltage determined based on the drive signal to the motor, wherein the control unit includes: a velocity detecting unit that detects a rotation velocity of the motor, a calculating unit that calculates a current applied to the motor based on the rotation velocity of the motor; a comparing unit that compares the current calculated by the calculating unit with a current limit; and an output unit that outputs the drive signal that decreases the voltage to a level lower than a voltage at the time of calculating the current when the current calculated by the calculating unit is larger than the current limit, wherein the calculating unit calculates a difference between the voltage determined based on the drive signal and an induced voltage that is proportional to the rotation velocity of the motor detected by the velocity detecting unit, and calculates the current based on the difference and an electric resistance of a coil of the motor.