| 摘要 |
A brushless motor operating apparatus includes a DC power source 1, a group 2 of semiconductor switching elements for passing/interrupting a current to an armature winding 4 of a brushless motor 3, a plurality of filter circuits 6 for waveform-processing induced voltages induced in the armature winding 4, a comparison circuit 7 for comparing outputs of the plurality of filter circuits 6 and a composite wave thereof, a control circuit 8 for making ON/OFF control of the semiconductor switching element group 2 in accordance with an output of the comparison circuit 7, the filter circuit 6 having a construction in which condensers 6c and 6e are connected behind and in series with a voltage divider circuit composed of a plurality of resistors 6a and 6b and an integrating circuit 6d is connected behind the condensers 6c and 6e, whereby the condensers 6c and 6e in the filter circuit 6 can be provided with ones having a low withstanding voltage, thereby making it possible to reduce the size and cost of the apparatus.
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