| 摘要 |
PURPOSE: A rotation velocity control circuit for a DC hood motor of an OTR(over the range) is provided to reduce the manufacturing cost and improve productivity by employing a DC motor instead of an AC motor as a hood motor and controlling the rotation velocity of the motor with the circuit instead of a temperature sensor, and prevent overload from being applied to the motor by opening a fuse in case of abnormal operation of the motor. CONSTITUTION: A rotation velocity control circuit for a DC hood motor of an OTR includes a rectifying circuit part(402) for outputting DC power from input AC voltage, an AC voltage blocking part(401) connected between the AC voltage and the rectifying circuit part for turning on/off the AC voltage with relation to the rectifying circuit part, a first control part(404) for outputting a first control signal according to a rotation velocity selection for the DC motor, a second control part(406) for outputting a second control signal according to the first control signal, a third control part for outputting a third control signal according to the second control signal, the third control signal having a higher frequency than the second control signal, a fourth control part to be turned on/off by the third control part for controlling the rotation velocity of the DC motor, a DC motor operation state monitoring part for sensing a change of current according to the normal and abnormal operation of the DC motor and outputting a voltage according to the current change, and an overload preventing part(408) to be turned on/off by the output voltage of the monitoring part for applying a part of the output voltage of the monitoring part to the output of the third control part to turn off the AC voltage by the AC voltage blocking part.
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