| 摘要 |
PURPOSE:To prevent a phase-lag, which is caused through a hysteresis means for removing noises and through the decreases of the time width of a spike voltage generated on the voltage across the terminals of a coil, by attenuating with resistors the negative input of a comparator in a circuit for sensing a position, and by advancing the phase of a comparison timing. CONSTITUTION:Resistors 82a, 83a produces hysteresis in a comparator 81a. A hysteresis voltage width VH is determined by a positive input voltage VI+ of the comparator 81a, its output voltage value VC, and the ratio of a resistance value R1 of the resistor 82a to a resistance value R2 of the resistor 83a. By a hysteresis means, a comparison timing is delayed. Therefore, by correcting the hysteresis voltage width VH through dividing a negative input voltage VI-of the comparator 81a with resistors 84a, 85a, the comparison timing is normalized. That is, the negative input voltage of the comparator 81a is made small, and as a result, the comparison timing is brought into a phase-lead. Thereby, a phase-lag, which is caused by a hysteresis means for removing noises and by the decrease of time width of a spike voltage, is eliminated, and the normal driving of a brushless motor can be performed. |
