| 摘要 |
PROBLEM TO BE SOLVED: To protect a power element that supplies current to an armature coil against destruction from heat, when the revolution of a rotor is locked. SOLUTION: A lock protection control means 12a receives sensor signals from Hall ICs 1-3, calculates the rotational speed of a motor from the cycle of the detected directional change of its magnetic field, and decides that the rotation is locked to give an instruction to stop the motor, when the rotational speed of a rotor is lower than preset revolutions, and when the revolutions indicated by a revolutions-indicating signal from a device for controlling air- conditioning are larger than a fixed number. A drive current control means 12b receives sensor signals and revolutions-indicating signal to control the revolutions. If instructions for stopping the motor is given, it also controls MOSFETs (switching elements) Q1 to Q6 to states of high impedance via a motor drive circuit 13.
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