Shift range control device

A shift range control device for controlling switching of a shift range by controlling drive of a motor having a three-phase motor winding, the shift range control device comprising:

• a signal receiver configured to acquire an encoder signal from an encoder capable of outputting three or more phase encoder signals having different phases;
• an abnormality monitor configured to monitor an abnormality of the encoder;
• and
• a drive controller configured to control the drive of the motor by switching an energized phase of the motor winding so that a rotation position of the motor becomes a target rotation position according to a target shift range, wherein
• when the abnormality monitor detects the abnormality of the encoder, the drive controller drives the motor by a faulty phase identification control to identify a faulty phase that is a phase in which an abnormality of the encoder signal occurs and a normal phase in which the encoder signal is normal,
• when the encoder is normal, the drive controller controls the drive of the motor by a normal time feedback control in which the energized phase is switched based on the encoder signals of all the phases,
• when the drive controller has identified the faulty phase, the drive controller controls the drive of the motor by a fault time feedback control in which the energized phase is switched based on the encoder signal of the normal phase, and
• when the drive controller performs the fault time feedback control from a start of switching of the shift range, the drive controller performs a first time energization control for maintaining energization to any two or one phase.