| 摘要 |
PURPOSE:To enhance reliability in protective operation by automatically interrupting operation of motor upon temperature rise of a brushless motor and sustaining the stopped state. CONSTITUTION:When air flow rate drops from steady state, temperature of the stator of a brushless motor 10 increases. Consequently, resistance and output voltage of a negative characteristic thermister 53 decrease and when the output voltage drops below a reference voltage set by a comparator 82, output of the comparator 82 goes high to turn transistors 83, 91 ON. Since a control terminal 83a goes low to close respective AND gates 70-75, switching transistors 63-68 are entirely turned OFF to interrupt DC current supply to driving coils 17a-17c thus stopping operation of the brushless motor 10. According to the constitution, positive protective operation is ensured. |
