Patent ID: 8760092

Claim:
A motor control system comprising: an electric motor for driving a controlled object; an encoder for outputting pulse signals at predetermined angular positions in synchronism with rotation of the electric motor; and a motor control unit having an encoder counter for counting the pulse signals from the encoder to calculate an encoder count value, wherein the motor control unit carries out an initial operation after a start-up of the motor control unit, so that current-supply phase of the electric motor is changed in an open-loop control, wherein the motor control unit carries out a learning process in the initial operation in order to learn a correction value of a phase difference between the current-supply phase and the encoder count value, wherein, in a normal motor operation after the initial operation, the motor control unit corrects the encoder count value by the correction value of the phase difference, wherein the motor control unit controls power supply to the electric motor so that the current-supply phase is sequentially changed depending on corrected encoder count value, in order to rotate the electric motor to a target position, wherein the motor control unit determines whether the electric motor is being rotated or not, after the start-up of the motor control unit but before the initial operation, and wherein the motor control unit carries out a motor-stop control, when the motor control unit determines that the electric motor is still being rotated, so as to stop rotation of a rotor of the electric motor before the initial operation.