Control device and control method for variable valve timing mechanism

A control device for a variable valve timing mechanism configured to detect a phase angle of a cam based on a cam signal and control the phase angle of the cam by using an electric motor, wherein

• the control device comprises a controller,
• the controller comprising:
• a motor torque estimation unit configured to receive a motor current, a power supply voltage, a driving duty, and a motor temperature and to estimate and output a motor torque according to at least one of the motor current, the power supply voltage, the driving duty, and the motor temperature based on characteristics of a DC motor;
• a motor rotation-angle estimation unit configured to receive the motor torque output from the motor torque estimation unit and influencing factors for an engine and to estimate and output a motor rotation angle by using the motor torque, an engine speed, an engine rotation angle, and an oil temperature based on an equation of motion of a motor rotation;
• a conversion unit configured to receive the motor rotation angle output from the motor rotation-angle estimation unit and to convert a unit of the motor rotation angle to a VTC conversion angle and output the VTC conversion angle;
• and
• a feedback control unit configured to receive the VTC conversion angle output from the conversion unit and the cam signal and to, when a VTC phase angle is detected based on the cam signal, calibrate a phase angle interpolated value to a detected value and output a calibrated VTC phase angle, wherein
• the controller is further configured to use the calibrated VTC phase angle to control the variable valve timing mechanism.