Sensorless brushless motor control circuit, sensorless brushless motor device, and vacuum pump device

摘要

PPROBLEM TO BE SOLVED: To provide a control circuit or the like of a brushless motor capable of properly controlling current of motor windings by detecting positions of magnetic poles of a rotor at a rotational frequency of the rotor from low-speed rotation which cannot lock a PLL circuit to high-speed steady-state rotation. PSOLUTION: The positions of the magnetic poles are detected from a change in a magnetic flux (magnetic flux signal) of the motor windings caused by rotating the rotor equipped with the magnetic poles, and by this, a synchronizing signal (ROT signal) in synchronism with rotation of the rotor is generated. When the rotor is rotated at a low rotational frequency which cannot lock the PLL circuit, the rotor is driven by using predetermined two of the output-enabled driving voltage vectors, and when the rotational frequency capable of locking the PLL circuit is reached, the rotor is driven by successively outputting the output-enabled driving voltage vectors in synchronism with the positions of the magnetic poles detecting the output-enabled driving voltage vectors. Moreover, the magnetic flux signal is obtained by using the voltage between two phases at which phases and magnitudes of voltage drop caused by inductances of the motor windings are equal to each other. PCOPYRIGHT: (C)2008,JPO&INPIT