| 摘要 |
PURPOSE:To make it possible to detect the rotor position of a brushless motor even under low speed rotation of motor without requiring a pole sensor. CONSTITUTION:Two phases of stator windings of a three-phase brushless motor 1 comprising the stator windings and a rotor having a permanent magnet are excited with an AC power supply 3 in two or more combination and exciting voltages and currents at that time are detected, respectively, through detectors 4, 5. A pole position operating circuit 10 determines an inductance value based on thus detected voltage and current thus detecting the rotor position of the brushless motor even at the time of starting or low speed rotation. Alternatively, the rotor position can be detected based on the variation of inductance when AC excitation is performed at a preset angle using the three-phase windings of stator. |
