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Motors PowerPoint Presentation

Motors

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Motors

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  1. Motors

  2. A current in a wire is subject to a magnetic force. Magnetic field out of loop Perpendicular to plane A loop of wire will have a force on each segment. Simplify as rectangle Force directed inward Wire Loop I FM FM FM B

  3. If the loop is feel to turn on one axis there will be a torque. Constant force on wires parallel to axis Varying lever arm depending on rotational position. Net torque to restore loop to 0° angle. Magnetic Torque l FM w FM B

  4. The loop would come to stable equilibrium from the torque. Flip current every half turn. Inertia pushes it past equilibrium Flipped torque from opposite current The field provides torque for the next half-turn. Repeat current flip Current Flips FM2 l FM1 w B

  5. Brushes and commutators provide a mechanical means to flip current. The coil is called the armature. Usually many loops Fixed permanent magnet provides the field. DC Motor Britannica.com

  6. A brushless motor puts the magnet on the rotating shaft. Switches control current flips to the electromagnets. Easier to cool Longer lasting Brushless Motor

  7. A galvanometer measures current with the motor principle. Current in a coil is deflected by a field. A spring provides a counter restoring force. Greater deflection comes from greater current. Galvanometer next