To provide a motor drive capable of preventing a motor from being stopped due to disturbance such as erroneous detection of overcurrent or a change in power voltage, keeping the duty of a PWM signal constant without changing its setting according to a change in DC voltage from a DC power circuit or conditions such as variance in parts and opposite rotation of the motor, and setting a permissible range sufficient for starting duty.
The electric current passing through a motor 10 is converted into voltage by a resistor 25. The overcurrent passing through the motor from the voltage is detected by an overcurrent detection circuit 4. While the overcurrent detection circuit 4 is detecting the overcurrent, a control circuit 3 gives a command of stopping the output of a PWM signal of preset duty to the MOS transistors 21u to 21w of a driving circuit 2.
OGAWA MASANORI
MATSUSHIRO HIDEO
MAEDA SHIRO
