The Charles Stark Draper Laboratory, Inc.

George A Oberbeck

David B Eisenhaure

James R Downer

Tim E Bliamptis

Susan D Hendrie

William E Stanton

Kenneth Fertig

Andrew W Stewart

An energy storage attitude control and reference system for a craft including at least two flywheels with their angular momenta balanced to produce zero net angular momentum and at least two motor/generator units each including one of the flywheels in its rotor structure. The system further includes one pair of bearings for supporting each of the flywheels, means for measuring the position of each flywheel relative to its bearings, means for resolving current to and from said motor/generator units, means for applying torques to each flywheel through its respective bearings for controlling attitude of the craft about two mutually perpendicular axes, and means for exerting torques to each flywheel through its respective motor/generator to provide attitude control of the craft about a third axis perpendicular to the first two and for controlling the energy storage level of the flywheels.

Energy storage attitude control and reference system

A magnetic suspension system including a first control coil for establishing circumferential current flow, and second and third control coils for establishing axial current flow. A support member of magnetic material has a gap for receiving the coils and there is a magnet for producing a magnetic field in the support member through the gap in the coils for generating Lorentz forces to support the coils in the axial and two mutually perpendicular radial directions.

Magnetic suspension system

A self-regulating energy storage system including: an a.c. motor/generator including a rotor; a flywheel attached to the motor/generator; a device for monitoring the position of the motor/generator rotor; an element for resolving current to and from the motor/generator; a pulse width modulated bidirectional inverter interconnecting the motor/generator with a power supply bus to be regulated; a summing circuit for determining differences between a reference voltage and the voltage in the power supply bus to be regulated; and a pulse width modulation switch control responsive to the comparator circuit, to the device for monitoring, and to the element for resolving, for actuating the inverter to increase pulse width as a function of increase in the difference between the reference voltage and the voltage on the bus, and to increase current to the motor/generator in the motor direction when the bus voltage exceeds the reference voltage and to increase current from the motor/generator in the generator direction when the reference voltage exceeds the bus voltage.

Self-regulating energy storage system

A power conversion system for converting between electrical power at different frequencies, including a rotary electrical machine including a rotor, a stator, first and second independently controllable field windings, and at least one armature winding for each phase; a switching circuit including a plurality of switching devices and having first terminal means interconnected with the armature winding which carries a high frequency signal established by the machine, and a second terminal for interconnection with an impedance establishing a lower frequency signal; the first field control circuit for monitoring the machine to sense phase difference between the optimum zero crossings and actual zero crossings of the higher frequency signal for driving the first field winding to adjust the phase of the higher frequency signal to minimize the phase difference; a second field control circuit for modulating the higher frequency signal carried by the armature winding with the lower frequency signal and for monitoring the second terminal means to sense amplitude difference between a selected one of the voltage and current parameters of the lower frequency signal and a reference level for driving the second field winding to adjust that parameter towards the reference level; and a switch firing circuit responsive to the machine voltage and one of the voltage and current parameters of the lower frequency signal at the second terminal means for selectively triggering to the on state and self-commutating to the off state the switching devices synchronously with the zero crossings of the higher frequency signal for transferring power between the higher and lower frequency signals through the switching circuit.

Rotary electric machine and power conversion system using same

A saturable reactor device for limiting alternating and direct current in an external electric circuit. In one form, the required magneto-motive force (mmf) bias for the saturable reactor is provided by a controllable flux bias element in order to minimize the required bias power. A current sensor provides a control signal representative of the alternating or direct current passing between the source and the load. This signal is used to control the magnitude of the bias so that the mmf provided by the bias element is a function of the current driving the load, permitting a current limiting threshold at a predetermined percentage of the current applied to the load. In an alternate form, the device may be adapted to limit bipolar current in the external circuit. In this form, the device includes an input circuit and an associated direct current saturable reactor limiter. In response to direct current of either positive or negative polarity passing through the external circuit, unidirectional current is driven through the input coil of the direct current limiter. The magnitude of the unidirectional current passing through the input coil is proportional to the magnitude of the current provided by the source. When the unidirectional current exceeds a predetermined threshold, the direct current limiter effectively provides a relatively high current-limiting impedance between the source and load of the external electric circuit. When the unidirectional current is below that threshold, the direct current limiter has minimal effect on the external electric circuit.

Saturable reactor limiter for current

A current limiter to protect circuit elements from excessive current caused by transient load impedance or power supply surges. A multiple branch element magnetic circuit includes at least one saturable branch element inductively coupled by a coil connected in series with the load of an external electric circuit. The magnetic circuit further includes lower permeance bias branch element which biases the saturable branch element in a low permeance, saturated state when current through the coil is below a predetermined threshold value, and which biases at least one saturable branch element in its high permeance, non-saturated state when current through the coil is in a predetermined range above and extending from the threshold value. A relatively high permeance shunt branch element provides a shunt path for magnetic flux. The coil provides a relatively high inductive impedance in series with the external electrical circuit when at least one saturable element is in its non-saturated state and provides a relatively low impedance otherwise.

Saturable reactor current limiter

A device for providing a displacement representative of the magnitude of a signal. The device typically includes a rotor having a plurality of sections of high permeability material separated by areas of high reluctance. A magnetic flux is applied to a section of the rotor to produce an elastic restraint torque varying with angle, while another high permeability section responds to variations in the magnetic flux caused by the signal to produce a torque representative of the signal magnitude. This latter torque moves the rotor to the point where the restraint torque increases sufficiently to balance the signal torque. The resultant angle of rotation represents signal magnitude. The device may also be operated to provide a signal output representative of an input torque or force.

Apparatus for providing a displacement representative of the magnitude

A current limiter to protect circuit elements from excessive current caused by transient load impedance or power supply surges. A multiple branch element magnetic circuit includes at least one saturable branch element inductively coupled by a coil connected in series with the load of an external electric circuit. The magnetic circuit further includes low permeance bias branch element which biases the saturable branch element in a low permeance, saturated state when current through the coil is below a predetermined threshold value, and which biases at least one saturable branch element in its high permeance, non-saturated state when current through the coil is in a predetermined range above and extending from the threshold value. A relatively high permeance shunt branch element provides a shunt path for magnetic flux. The coil provides a relatively high inductive impedance in series with the external electrical circuit when at least one saturable element is in its non-saturated state and provides a relatively low impedance otherwise.

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Belmont, MA, United States of America

George A Oberbeck