CONTROL CIRCUIT OF BRUSHLESS MOTOR, CONTROL CIRCUIT OF SENSORLESS BRUSHLESS MOTOR, BRUSHLESS MOTOR DEVICE, SENSORLESS BRUSHLESS MOTOR DEVICE, AND VACUUM PUMP EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To provide a control circuit of a brushless motor or the like which can control adequately a current of a motor winding by detecting the position of a magnetic pole of a rotor until a rotating frequency of the rotor reaches stationary rotation at a high speed from low speed rotation which a PLL circuit cannot lock. SOLUTION: The position of a magnetic pole is detected from the change of magnetic flux (magnetic flux signal) of the motor winding which is generated by the rotation of a rotor provided with the magnetic pole, thereby forming a synchronous signal (ROT signal) which synchronizes with the rotation of the rotor. When the rotor rotates at a low rotating frequency which the PLL circuit cannot lock, the rotor is driven by using two prescribed driving voltage vectors from among driving voltage vectors which can be outputted. When the rotating frequency reaches a frequency which the PLL circuit can lock, the rotor is driven by outputting driving voltage vectors in sequence synchronously with the position of the magnetic pole where the driving voltage vector which can be outputted is detected. The magnetic signal is obtained by using a voltage between two phases where phases and amplitudes of voltage drops due to inductance of the motor winding become equal.