Ripple detection device and seat device

A seat device, comprising:

• a seat mounted on a vehicle, a position or an angle of the seat being adjustable by a motor;
• a drive controller configured to control drive of the motor;
• and
• a ripple detection device configured to detect a ripple current of the motor and output the ripple current to the drive controller,
• wherein the ripple detection device includes:
• a ripple current detector configured to detect the ripple current generated when the motor is driven;
• a motor voltage detector configured to detect a terminal-to-terminal voltage of the motor;
• a variable filter configured to pass a component of the ripple current detected by the ripple current detector, the component being in a predetermined frequency band;
• and
• a frequency adjuster configured to adjust the predetermined frequency band of the variable filter so as to include a frequency of the ripple current derived by using a linear relational expression for deriving the frequency of the ripple current based on the ripple current detected by the ripple current detector and the terminal-to-terminal voltage detected by the motor voltage detector.