ACTUATOR DRIVE DEVICE AND STEERING SYSTEM PROVIDED WITH SAME

When the DC power supply fails, the control unit (40) performs the following control in a power supply failure recovery process for determining the restart of normal control, which is control for the normal time of the DC power supply. [1] When the inverter input voltage has recovered from the time of a power supply failure until a standby period has elapsed, the normal control is resumed. When a standby period has elapsed in a state in which the holding voltage is not recovered, the power supply relay (31) is turned off. [2] The power supply relay (31) is turned on again when a power supply relay turn-off period has elapsed from the turn-off time. When the inverter input voltage is recovered at the time of turning on, the normal control is restarted. [3] When the inverter input voltage has recovered from the ON time until the power supply relay has passed the ON time, the normal control is resumed. When a power supply relay ON period has elapsed in a state in which the holding voltage is not recovered, the p