US 4,303,871 AGranted

Nutating motor current control

AssigneeMorgan Actuators, Inc.

InventorEddie T. Berry

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Abstract

A current sensing circuit monitors the currents flowing through the stator windings of a nutating motor. The current drive circuits for the windings are capable of delivering large currents with a fast rise time so that the magnetic circuits of the nutating motor quickly saturate, providing precise operation of the motor. Steering diodes quickly discharge the windings into the power supply. When a predetermined winding current level is exceeded, the current sensing circuit produces an output signal which momentarily disables the current drive circuits for the windings so that the stator winding currents are limited to levels sufficient to precisely operate the nutating rotor. The sensing circuit has a hysteresis characteristic which in conjunction with the energy stored in a winding causes the current in a winding to be maintained between certain maximum and minimum levels.

Claims12

Dependent claims

A system for controlling the current in an inductive winding of a motor, said motor operated from a power supply, comprising:

a first switch means coupled between a first terminal of the power supply and a first terminal of the winding;
a second switch means coupled between a second terminal of the power supply and a second terminal of the winding;
means for sensing the current in the winding;
comparator means coupled to the sensing means and providing an output signal indicative of the winding current exceeding a predetermined maximum level;
means for controlling the first and second switch means, said control means turning off the first and second switches in response to the indicative signal so that the winding current is limited to the predetermined maximum level;
and
steering means for allowing the winding current to flow from the second terminal of the winding to the first terminal of the power supply and from the first terminal of the winding to the second terminal of the power supply while limiting the reverse emf to approximately the power supply voltage when the first and second switch means are turned off so that energy stored in the winding is returned to the power supply.

4 more elements

Dependencies are inferred from the claim text.