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US 5,294,874 AGranted
Dynamic brake circuit for an electric motor
AssigneeMilwaukee Electric Tool Corporation
InventorsJeffrey C. Hessenberger, Michael R. West
Life of this patent
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AssigneeMilwaukee Electric Tool Corporation
InventorsJeffrey C. Hessenberger, Michael R. West
Estimating the term…
A universal electric motor having an arbor mounted on a rotating armature with a run winding for generating a magnetic field having a polarity relative to the armature and for rotating the arbor, a first switch for connecting the run winding to a power source, and a brake winding for generating a counter magnetic field opposed with respect to the armature winding to that generated by the run winding. The brake winding operates when energized, to stop rotation of the arbor by generating a counter magnetic field which interacts with the magnetic field of the armature Also included is an electrical circuit for providing a residual magnetism in the stator iron to help stop the arbor rotation The circuit includes an energy storage capacitor for providing current to the brake winding thereby helping to begin generation of the counter magnetic field, a second switch for connecting the energy storage to the brake winding when the first switch disconnects the run winding from the power source, a biasing diode for biasing the energy storage capacitor to a predetermined polarity, a rectifying resistor and diode for coupling the energy storage capacitor to the power source and an alternate discharge path for discharging the energy stored in the event that the normal discharge path is inoperative.
An electric motor including an arbor mounted on a rotating armature means, a stator iron, run winding means mounted on the stator iron for generating a magnetic field for rotating the arbor, first switching means for connecting the run winding means to a power source, brake winding means which is separate from said run winding means and which generates a counter magnetic field opposed, with respect to the armature, to that field generated by the run winding means, the brake winding means operating when energized to stop rotation of the arbor, and a control circuit for generating residual magnetism in the stator iron, the circuit comprising:
An electric motor having a rotating arbor, a stator iron, run field winding means mounted on the stator iron and brake field winding means which is separate from and which is connected to said run field winding means, and an electrical circuit for generating residual magnetism in the stator iron, the circuit comprising:
Dependencies are inferred from the claim text.