| 摘要 |
PURPOSE:To obtain an expected revolution when a forced rotation is finished and realize the stability of the generation of a counter electromotive force when a sensorless motor(SM) is started by a method wherein the excited phase switching control of the SM is performed in accordance with a predetermined constant accelera tion curve to make the SM rotate forcibly. CONSTITUTION:A motor control part 2 puts a phase number counter A into an initial state and outputs an excited phase control signal 5 of an Ath phase and, further, calculates a phase time of the Ath phase in accordance with a predetermined constant acceleration curve and waits for a period of one phase time. Then the motor control part 2 gives an increment to the phase number counter A and outputs the excited phase control signal 5 of the next phase. The motor control part 2 compares the value of the phase number counter A with a phase number B which is predetermined by the characteristics of the motor. If the predetermined number of phases of a forced rotation are finished, the start of the steady rotation of the rotor is judged in accordance with a rotor position signal 7 given by a rotor position detector 4. If the rotor is made to rotate and a stable counter electromotive force is generated, the rotor position signal 7 is changed to an expected output, so that the start of the steady rotation of the rotor can be judged. |
