To provide a motor control device that can prevent reduction in circuit scale and the breakage of a motor by detecting an overload of the motor by the change of a temperature caused by an increase in a drive current flowing to the motor.
In this motor control device 1, when the overload is applied to the motor 3 and the drive current I is increased to be an overcurrent, the temperature of an FET 4 is raised, a temperature detection diode 5 detects the rise of the temperature, and a voltage V1 is lowered. A differential amplifier 9 differential-amplifies the voltage V1 and a voltage V2 of a diode 7, and a differentiating circuit 10 generates the change rate of the amplification, and a comparator 11 compares the change rate with a threshold V3. When the change rate exceeds the threshold V3, a control circuit 12 turns off the FET 4, and stops the overcurrent.
Iwa Saki Kokuni
Akira Kurihara
Kawamata Sumio
Masakazu Ito
Shunichi Takahashi
Toshio Takamatsu