| 摘要 |
PURPOSE:To prevent a circuit from damaging due to an overload if a fan is externally forcibly driven by turning OFF all semiconductor switches when an outer air speed exceeds a reference value. CONSTITUTION:An outer air speed is detected by an outer air speed detecting means 7, compared with a reference value by outer air speed judging means 8, and, when it exceeds a reference value, all elements of semiconductor switch group 2 are turned OFF through driving means 6. Thus, an excess currents flowing to the windings of a brushless motor and the group 2 are prevented, and a hunting is also prevented. |
