초록 ▼

Electric power is stored in a flywheel system, from a DC power buss, and supplied to the buss, through power electronics associated with a motor/generator, its rotor integral with a flywheel supported by magnetic bearings. The power is reciprocally converted by the motor/generator, controlled by cur

Electric power is stored in a flywheel system, from a DC power buss, and supplied to the buss, through power electronics associated with a motor/generator, its rotor integral with a flywheel supported by magnetic bearings. The power is reciprocally converted by the motor/generator, controlled by current in its polyphase stator windings, between electricity and kinetic energy. The rotor contains radial-field permanent magnets attached to supporting outer annular high-permeability steel, attached to inner annular steel. This completes a path through the stator windings, for the rotor field, which interacts with current in the windings, to produce torque between the rotor and the stator. Polyphase sinusoidal currents in the stator windings are controlled by the associated electronics, responsive to respective rotation angle sensors and the DC power buss voltage, plus other commands. During normal operation, the rotor assembly is supported by axial attraction of its annular high-permeability axial poles near its top and bottom, to fixed juxtaposed annular magnetic poles above and beneath it. The axial magnetic field also provides passive radial centering. The rotor assembly is released by mechanical backup bearings as magnetic bearings are activated at power-up, and then normally remain disengaged until the last event of a power-down sequence. Axial position stability is provided by axial electromagnets at each end of the rotor assembly. A coil current time-integral is combined with axial position and rate feedback, so that average coil current is continuously adjusted to zero, by axial position adjustment. Radial electromagnets damp flywheel swirling at resonant vibration frequencies, and constrain radial position during possible earth tremors. Affixed to orbital satellites, arrayed 2, 3, or 4 flywheel systems can provide power storage and regeneration as needed. Their radial servos can also provide spin axis precession torques to control satellite attitude.

대표청구항 ▼

1. A flywheel system intended for terrestrial use, for storing electric power from a DC power buss as kinetic energy and returning power to said buss with minimal losses, comprising:motor/generator means, including polyphase stator windings for conducting polyphase sinusoidal currents, which are for

1. A flywheel system intended for terrestrial use, for storing electric power from a DC power buss as kinetic energy and returning power to said buss with minimal losses, comprising:motor/generator means, including polyphase stator windings for conducting polyphase sinusoidal currents, which are formed from multi-strand insulated conductors for eddy blocking and bucking, a permanent-magnet rotor for providing radial flux that interacts with said currents, and rotor angle sensors, for providing polyphase feedback signals which vary essentially sinusoidally with rotor angle;power interface electronics, connected to the DC power buss and to the polyphase stator windings of the motor/generator, said electronics responsive to the rotor angle sensors and to the DC buss voltage, for controlling polyphase current through the stator windings so its resultant magnetic field rotates synchronously with the rotor, and also responsive to power-up and power-down algorithms, and to other commands;a vacuum enclosure, containing mounting therein for the motor/generator, a rim affixed to its rotor, the rotor angle sensors, magnetic bearings, EMI shielding means, and hermetic connections to power interface electronics outside the enclosure;a flywheel rim, attached to and surrounding the rotor and coaxial therewith, the combination having a vertical spin axis, to provide rotary inertia for storing kinetic energy;axial servo means, including axial position sensors, an annular permanent-magnet and coil with concentric magnetic materials above the rotor to lift and passively center it, plus a coil and concentric magnetic materials below the rotor to alternately apply a downward force, and servo electronics that includes an integrator to adjust axial rotor position for zero coil currents at steady-state;radial servo means, having electronics responsive to radial position sensors at the rotor top and bottom, including radial electromagnets aligned thereto, for radially centering the rotor by forces from magnetic fields with flux paths substantially radial and axial in the rotor, plus dead-band means wherein steady-state centering is maintained by passive axial magnetics and gravity;vibration discriminator means, responsive to signals from the axial and radial servos, for initiating a power-down algorithm;mechanical backup bearings, near the top and bottom of the rotor, and normally not in contact with it, for supporting the rotor when the axial and radial servos are not operating. 2. A flywheel system intended for use onboard orbital satellites, for storing electric power from a DC power buss as kinetic energy and returning power to said buss with minimal losses, and for controlling the satellite angular attitude, comprising:motor/generator means, including polyphase stator windings for conducting polyphase sinusoidal currents, which are formed from multi-strand insulated conductors for eddy blocking and bucking, a permanent-magnet rotor for providing radial flux that interacts with said currents, and rotor angle sensors, for providing polyphase feedback signals which vary essentially sinusoidally with rotor angle;power interface electronics, connected to the DC power buss and to the polyphase stator windings of the motor/generator, said electronics responsive to the rotor angle sensors and to the buss voltage, for controlling polyphase current through the stator windings so its resultant magnetic field rotates synchronously with the rotor, and also responsive to power-up and power-down algorithms, and to other commands;a flywheel assembly housing, containing mounting therein for the motor/generator, a rim affixed to its rotor, the rotor angle sensors, magnetic bearings, EMI shielding means, and connections to power interface electronics;a flywheel rim, attached to and surrounding the rotor and coaxial therewith, for providing rotary inertia,axial servo means, including axial position sensors, an annular permanent-magnet and coil with concentric magne tic materials above the rotor to lift and passively center it at the top, plus a like magnet and coil and concentric magnetic materials below the rotor, to provide alternately opposing axial force and passive centering at the bottom, and servo electronics that includes an integrator to adjust axial rotor position for zero coil currents at steady-state;radial servo means, including electronics responsive to radial position sensors at the rotor top and bottom, including radial electromagnets aligned thereto, for radially centering the rotor by forces from magnetic fields with flux paths substantially radial and axial in the rotor, plus dead-band means wherein steady-state centering is maintained by passive axial magnetics, plus means to apply equal opposing radial forces at opposite ends, for producing precession torques;vibration discriminator means, responsive to signals from the axial and radial servos, for initiating a power-down algorithm;mechanical backup bearings, near the top and bottom of the rotor, and normally not in contact with it, for supporting the rotor when the axial and radial servos are not operating. 3. The power interface electronics in claim 1, comprising:signal processing means, responsive to the rotor angle sensors, the DC power buss voltage, to the vibration discriminator, and to input commands, for controlling PWM H-bridges;PWM H-bridges, responsive to the signal processing means, connected, with parallel capacitors, across the DC power buss, and through series output inductors to respective stator windings, including diagonal pairs of switch-mode transistors wherein one transistor of each pair has turn-off delay in drive mode, for controlling sinusoidal polyphase currents through the stator windings, and for exchanging DC current with the DC power buss;a vibration discriminator, responsive to signals from the axial and radial servos, including comparators which monitor amplitudes and durations above prescribed levels of said signals, and provide an output signal when said amplitudes and durations exceed prescribed levels;power-up algorithm means, initiated by an operator command signal, to control a sequence of coordinated actions by the flywheel system, that include disengaging the mechanical backup bearings and enabling drive to the regenerative motor;power-down algorithm means, initiated externally by an operator command signal and internally by a signal from the vibration discriminator, to control a sequence of coordinated actions by the flywheel system, that include inhibiting drive to the regenerative motor, decelerating the rotor assembly, and engaging the mechanical backup bearings. 4. The motor/generator in claim 1, comprising:polyphase stator windings, formed from multi-strand conductors that provide means for blocking and bucking eddy currents therein, embedded in a non-magnetic cylinder affixed to the enclosure, to conduct polyphase currents varying sinusoidally with rotor angle so the resulting stator field is synchronized to rotor angle, for producing torque between the rotor and the stator, and for exchanging electric power with the power interface electronics without incurring hysteresis and eddy losses,rotor angle sensor means, for providing polyphase feedback signals which vary sinusoidally with rotor angle;at least one pair of rotor magnets, with one magnet of the pair magnetized radially outward and the other magnetized radially inward, to provide flux, which varies substantially sinusoidally with rotor angle, through the stator windings;an outer cylinder of high-permeability steel, for supporting the magnets attached therein and for providing an outer flux return path;an inner cylinder of high-permeability steel, attached to the outer cylinder, for providing an inner flux return path, and for completing through the stator windings a flux pattern which rotates synchronously with the rotor;cylindrical high-permeability steel, attached therewith, for completing peripheral magnetic pat hs for the rotor field through the rotor angle sensors, to shield the rotor angle sensors from magnetic fields caused by stator current, and to prevent magnetic cycling in stator materials from the rotating peripheral rotor field. 5. The axial servo means in claim 1, comprising:a fixed annular permanent-magnet, with high-permeability annular steel poles, above the rotor assembly, within and supported by the vacuum enclosure, to provide an axial magnetic field uniform with rotor angle in an annular gap region above the rotor assembly;an annular, concentric coil, affixed to the permanent-magnet and steel poles above the rotor assembly, for adjusting and stabilizing the magnetic field in the upper annular gap region;a second annular, concentric coil, affixed to annular steel poles below the rotor assembly, for alternately adjusting and stabilizing the magnetic field in the lower annular gap region;rotatable annular high-permeability steel poles, attached to the rotor assembly near its top, and juxtaposed beneath the fixed permanent-magnet, poles, and concentric coil, to provide axial lift and radial centering forces, for the rotor assembly;rotatable annular high-permeability steel poles, attached to the rotor assembly near its bottom, and juxtaposed above the lower fixed poles and concentric coil, to alternately provide downward force, to cooperate in axially positioning and stabilizing the rotor assembly;axial position sensors, for detecting the rotor assembly axial position;axial servo loops, responsive to the axial position sensors, for controlling current through the concentric coils, to stabilize and adjust axial position of the rotor assembly;integrator means, responsive to the concentric coil current, for adjusting axial position of the rotor and flywheel, so that long-term coil current is reduced to nearly zero. 6. The radial servo means in claim 1, comprising:four radial electromagnets at each end of the rotor assembly, positioned as opposing pairs 90° apart, each including a coil around high-permeability steel, its two poles in juxtaposition with the rotor to conduct a magnetic field having a substantially radial and axial path in the rotor, for providing radial attraction forces between the electromagnets and cooperating cylindrical high-permeability steel attached to and coaxial with the rotor assembly, with minimal flux cycling and no flux reversal in the cooperating magnetic materials;four radial position sensors, each aligned with a corresponding radial electromagnet;four radial servos, responsive to the radial position sensors, for controlling current through the coils of the radial electromagnets, including dead-band means, for inhibiting said current when the flywheel assembly spin-axis is centered within tolerance and rate of radial motion is less than a prescribed level, to maintain spin-axis centering and verticality during normal operation, by passive magnetics and gravity. 7. The polyphase stator windings in claim 4, each comprising:a group of conductor strands, each insulated from the other, formed in their inactive region between their two straight axial active segments, so as to interchange strands about the group center, to equalize, between winding terminal connections, back-EMF of each strand. 8. The polyphase stator windings in claim 4, each comprising:a group of conductor strands, each insulated from the others between winding terminal connections, the group spiraled, to equalize, between winding terminal connections, back-EMF of each strand. 9. Mechanical backup bearings as in claim 1, for axially and radially supporting the rotor assembly when the axial and radial servo means are not operating, comprising:a fixed surface contact pad, not normally in contact with any rotor assembly part during system operation, near the top of the rotor assembly;an axially movable surface contact pad near the bottom of the rotor assembly, that can be moved and supported by a motor-driven jackscrew mechanism re sponsive to power-up and power-down algorithms, which can lift the pad to engage a bottom surface contact pad affixed to the rotor assembly, and can alternately lower the pad to disengage;a surface contact pad, affixed to the rotor assembly near its top, in juxtaposition with the fixed surface contact pad near the top of the rotor assembly;a surface contact pad, affixed to the rotor assembly near its bottom, in juxtaposition with the axially movable pad. 10. The axial position sensor in claim 1, comprising:high-frequency oscillator means, to supply an excitation voltage,a pair of fixed and opposing conductive exciter rings, connected to the excitation voltage;a pair of rotatable conductive rings, attached to the rotor assembly by means of an insulating annular member and having surfaces capacitively coupled to the exciter rings;a pair of fixed conductive sensor rings, capacitively coupled to the rotatable rings, for providing opposing signals responsive to capacitance between the sensor rings and rotatable rings in series with capacitance between the exciter rings and rotatable rings. 11. The radial position sensors in claim 1, at each end of the rotor assembly, each comprising:high-frequency oscillator means, to supply an excitation voltage;a fixed conductive exciter cylinder, connected to the excitation voltage;a rotatable conductive cylinder, attached to the rotor assembly by means of an insulating annular member, and having a surface capacitively coupled to the exciter cylinder;four fixed sensor electrodes, 90° apart, capacitively coupled to the rotatable cylinder, for providing two signal pairs, each pair responsive to capacitance difference between opposing sensor electrodes and the rotatable cylinder. 12. The power interface electronics in claim 2, comprising:signal processing means, responsive to the rotor angle sensors, the DC power buss voltage, to the vibration discriminator, and to input commands, for controlling PWM H-bridges;PWM H-bridges, responsive to the signal processing means, connected, with parallel capacitors, across the DC power buss, and through series output inductors to respective stator windings, including diagonal pairs of switch-mode transistors wherein one transistor of each pair has turn-off delay in drive mode, for controlling sinusoidal polyphase currents through the stator windings, and for exchanging DC current with the DC power buss;a vibration discriminator, responsive to signals from the axial and radial servos, including comparators which monitor amplitudes and durations above prescribed levels of said signals, and provide an output signal when said amplitudes and durations exceed prescribed levels;power-up algorithm means, initiated by an operator command signal, to control a sequence of coordinated actions by the flywheel system, that include disengaging the mechanical backup bearings and enabling drive to the regenerative motor;power-down algorithm means, initiated externally by an operator command signal and internally by a signal from the vibration discriminator, to control a sequence of coordinated actions by the flywheel system, that include inhibiting drive to the regenerative motor, decelerating the rotor assembly, and engaging the mechanical backup bearings;means for linking the power interface of each flywheel system, in combinations of systems aboard a satellite, to match regenerative motor torques and speeds of each system. 13. The motor/generator in claim 2, comprising:polyphase stator windings, formed from multi-strand conductors that provide means for blocking and bucking eddy currents therein, embedded in a non-magnetic cylinder affixed to the enclosure, to conduct polyphase currents varying sinusoidally with rotor angle so the resulting stator field is synchronized to rotor angle, for producing torque between the rotor and the stator, and for exchanging electric power with the power interface electronics without incurring hysteresis and eddy losses;rotor angle senso r means, for providing polyphase feedback signals which vary substantially sinusoidally with rotor angle;at least one pair of rotor magnets, with one magnet of the pair magnetized radially outward and the other magnetized radially inward, to provide flux, which varies sinusoidally with rotor angle, through the stator windings;an outer cylinder of high-permeability steel, for supporting the magnets attached therein and for providing an outer flux return path;an inner cylinder of high-permeability steel, attached to the outer cylinder, for providing an inner flux return path, and for completing through the stator windings a flux pattern which rotates synchronously with the rotor;cylindrical high-permeability steel, attached therewith, for completing peripheral magnetic paths for the rotor field through the rotor angle sensors, to shield the rotor angle sensors from magnetic fields caused by stator current, and to prevent magnetic cycling in stator materials from the peripheral rotor field. 14. The axial servo means in claim 2, comprising:a fixed annular permanent-magnet, with high-permeability annular steel poles, above the rotor assembly, within and supported by the flywheel assembly housing, to provide an axial magnetic field uniform with rotor angle in an annular gap region above the rotor assembly;an annular, concentric coil, affixed to the permanent-magnet and steel poles above the rotor assembly, for adjusting and stabilizing the magnetic field in the upper annular gap region;a like magnet and concentric coil, affixed to annular steel poles below the rotor assembly, for alternately adjusting and stabilizing the magnetic field in the lower annular gap region;rotatable annular high-permeability steel poles, attached to the rotor assembly near its top, and juxtaposed beneath the upper fixed permanent-magnet, poles, and concentric coil, to cooperatively provide upward magnetic force and passive radial centering forces there, for the rotor assembly;rotatable annular high-permeability steel poles, attached to the rotor assembly near its bottom, and juxtaposed above the lower fixed poles, magnet, and concentric coil, to alternately cooperatively provide downward force, for axially positioning and stabilizing the rotor assembly, and passively centering it there;axial position sensors, for detecting the rotor assembly axial position;axial servo loops, responsive to the axial position sensors, for controlling current through the concentric coils, to stabilize and adjust axial position of the rotor assembly;integrator means, responsive to the concentric coil current, for adjusting axial position of the rotor and flywheel, so that long-term coil current is reduced to nearly zero. 15. The radial servo means in claim 2, comprising:four radial electromagnets at each end of the rotor assembly, positioned as opposing pairs 90° apart, each including a coil around high-permeability steel, its two poles in juxtaposition with the rotor to conduct a magnetic field having a substantially radial and axial path in the rotor, for providing radial attraction forces between the electromagnets and cooperating cylindrical high-permeability steel attached to and coaxial with the rotor assembly, with minimal flux cycling and no flux reversal in the cooperating magnetic materials;four radial position sensors, each aligned with a corresponding radial electromagnet;four radial servos, responsive to the radial position sensors, for controlling current through the coils of the radial electromagnets, to maintain spin-axis centering and alignment;a force sensor between each electromagnet core and its support, each said sensor to provide a signal proportional to the radial force therebetween;a precession torque command loop associated with each servo, to selectively apply equal opposing radial forces at opposite ends of the rotor assembly, for applying precession torque to the rotor assembly. 16. The polyphase stator windings in claim 13, each comprising:a group of conductor strands, each insulated from the other, formed in their inactive region between their two straight axial active segments, so as to interchange strands about the group center, to equalize, between winding terminal connections, back-EMF of each strand. 17. The polyphase stator windings in claim 13, each comprising:a group of conductor strands, each insulated from the others between winding terminal connections, the group spiraled, to equalize, between winding terminal connections, back-EMF of each strand. 18. Mechanical backup bearings as in claim 2, for axially and radially supporting the rotor assembly when the axial and radial servo means are not operating, comprising:a fixed surface contact pad, not normally in contact with any rotor assembly part during system operation, near the top of the rotor assembly;an axially movable surface contact pad near the bottom of the rotor assembly, that can be moved and supported by a motor-driven jackscrew mechanism responsive to power-up and power-down algorithms, which can lift the pad to engage a bottom surface contact pad affixed to the rotor assembly, and can alternately lower the pad to disengage;a surface contact pad, affixed to the rotor assembly near its top, in juxtaposition with the fixed surface contact pad near the top of the rotor assembly;a surface contact pad, affixed to the rotor assembly near its bottom, in juxtaposition with the axially movable pad. 19. Mechanical backup bearings as in claim 2, for axially and radially supporting the rotor assembly when the axial and radial servo means are not operating, so that both axial support magnets have closed magnetic paths, comprising:a fixed surface contact pad, not normally in contact with any rotor assembly part during system operation, near the top of the rotor assembly;a surface contact pad, affixed to the rotor assembly near its top, in juxtaposition with the fixed surface contact pad near the top of the rotor assembly;a component group, including the lower axial magnet, associated steel poles, and concentric electromagnet coil, including a surface contact pad attached therewith, near the bottom of the rotor assembly, where the group can be moved axially and supported by a motor-driven jackscrew mechanism responsive to the power-up and power-down algorithms, so that the jackscrew can lift the group whereby the attached pad engages a bottom surface contact pad affixed to the rotor assembly, and whereby the jackscrew can alternately lower the group to disengage the pads;a surface contact pad, affixed to the rotor assembly near its bottom, in juxtaposition with the axially movable pad. 20. The axial position sensor in claim 2, comprising:high-frequency oscillator means, to supply an excitation voltage;a pair of fixed and opposing conductive exciter rings, connected to the excitation voltage;a pair of rotatable conductive rings, attached to the rotor assembly by means of an insulating annular member and having surfaces capacitively coupled to the exciter rings;a pair of fixed conductive sensor rings, capacitively coupled to the rotatable rings, for providing opposing signals responsive to capacitance between the sensor rings and rotatable rings in series with capacitance between the exciter rings and rotatable rings. 21. The radial position sensors in claim 2, at each end of the rotor assembly, each comprising:high-frequency oscillator means, to supply an excitation voltage;a fixed conductive exciter cylinder, connected to the excitation voltage;a rotatable conductive cylinder, attached to the rotor assembly by means of an insulating annular member, and having a surface capacitively coupled to the exciter cylinder;four fixed sensor electrodes, 90° apart, capacitively coupled to the rotatable cylinder, for providing two signal pairs, each pair responsive to capacitance difference between opposing sensor electrodes and the rotatable cylinder. 22. Mechanical backup bearings as in claim 1, near each end of the rotor assembly, each bearing also including:a ball bearing having a fixed outer race and a rotatable inner race, and a plurality of load-bearing balls therebetween, which roll in contact with the inner and outer race;separators between each of the balls, formed from thin-wall tubing of a spring material, each having a neck at its center to maintain rolling contact with two balls, and having necks near both of its ends for maintaining rolling contact with idler races;outer idler races at both sides of the bearing, to provide outer raceways for the necks of each separator near their respective ends;inner idler races at both sides of the bearing, to provide inner raceways for the necks of each separator near their respective ends;axial grooves along the inner circumference of the inner idler race, to increase its radial compliance during assembly;a cover at each side of the bearing, each having a radially rigid inner shoulder to stiffen the adjoining inner idler race;means for affixing the covers to the outer race of the ball bearing. 23. Axial servo electronics as in claim 1, including:current rectifier and filter means, connected to respective sensor electrodes, for removing the high-frequency component from the signals provided by the sensor rings;differential amplifier means, for providing two amplified signal pairs, responsive to the rotor assembly radial position and excursion rate;operational amplifier means, for providing pairs of outputs to respective axial servo PWM electromagnet coil drives, proportional to the difference between the amplified opposing signals and excursion rate, and the output of an integrator;said integrator, responsive to the difference of current in the two coils. 24. Radial servo electronics as in claim 1, including:current rectifier and filter means, connected to respective sensor electrodes, for removing the high-frequency component from signals provided by the sensor electrodes;differential amplifier means, for providing two amplified signal pairs, responsive to the rotor assembly radial position;operational amplifier means, for providing pairs of outputs to respective radial servo PWM electromagnet coil drives, proportional to the difference between the amplified opposing signals and excursion rate, having a prescribed dead-band. 25. Three of the flywheel systems recited in claim 2, arrayed in combination, affixed to a satellite so that the spin vectors of their respective rotor assemblies are parallel to a common plane and separated 120° from each other, and each having radial servos responsive to precession torque commands, wherein:a pair of the flywheel systems, each having a radial electromagnet of one in the pair with means to apply a radial force parallel to the plane at the arrow-head end of its rotor assembly spin axis, while the electromagnet at its opposite end applies an opposite force, and having a like radial electromagnet of the second flywheel system in the pair to apply a like but opposite, radial force at a similarly disposed end, while the electromagnet at its opposite end applies an opposite radial force, so that opposing precession torques parallel to the plane are applied to the two rotor assemblies of that flywheel system pair, for causing satellite precession around the third flywheel system spin axis;the three flywheel systems, each having a like disposed radial electromagnet with means to apply radial force to its rotor assembly at the arrow-bead end of its spin axis, perpendicular to the plane, while the three electromagnets at the other ends of the three rotor assemblies apply opposite forces perpendicular to the plane, for causing satellite precession around an axis perpendicular to the plane. 26. Two of the flywheel systems recited in claim 2, arrayed in combination, affixed to a satellite so that the spin vectors of their respective rotor assemblies are in a common plane and 180° from each other, each having radial servos responsive to precession tor que commands, wherein:one of the two flywheel systems, having a radial electromagnet at one end of its rotor assembly with means to apply a radial force to it, perpendicular to the plane, while the radial electromagnet at its other end applies an opposite radial force, and the radial electromagnets of the second flywheel system apply like opposite radial forces, so that opposing precession torques parallel to the plane are applied to the two rotor assemblies, for causing satellite precession around an axis perpendicular to the plane;one of the two flywheel systems, having a radial electromagnet at one end of its rotor assembly with means to apply a radial force to it, parallel to the plane, while the radial electromagnet at its other end applies an opposite radial force, and the radial electromagnets of the second flywheel system apply like opposite radial forces, so that opposing precession torques perpendicular to the plane are applied to the two rotor assemblies, for causing satellite precession around an axis perpendicular to the spin axes and parallel to the plane;the regenerative motor of one flywheel system, with means to apply torque to accelerate its rotor assembly around its spin axis, while the regenerative motor of the second flywheel system applies torque to decelerate its rotor assembly, so that their combined reaction torques rotate the satellite around an axis parallel to the flywheel system spin axes. 27. Four of the flywheel systems recited in claim 2, arrayed in combination, affixed to a satellite so that the spin vectors of their respective rotor assemblies are in a plane, with a first pair 180° from each other, and a like second pair disposed 90° from the first pair, and each having radial servos responsive to precession torque commands, wherein:the four flywheel systems, each having a radial electromagnet at the arrow-head end of each rotor assembly spin vector, with means to apply a radial force perpendicular to the plane, while the radial electromagnet at the opposite end applies an opposite force of equal magnitude, for causing satellite precession around an axis perpendicular to the plane;the radial electromagnet at the arrow-head of a first rotor assembly spin vector, with means to apply a force parallel to the plane, while the radial electromagnetic at its opposite end applies an opposite radial force of equal magnitude, while like but opposite radial forces are applied to a second rotor assembly whose spin vector is disposed 180° from the first, so that opposing precession torques parallel to the plane are applied to the two rotor assemblies, for causing satellite precession around the spin axes of the other two rotor assemblies. 28. The EMI shielding means in claim 1, comprising:high-magnetic-permeability annular steel, for providing closed magnetic flux paths for the rotor magnets, through the rotor angle sensors, for preventing this rotating peripheral flux from cycling stator material, and for suppressing magnetic fields from current in the stator conductors from reaching the rotor angle sensors. 29. The EMI shielding means in claim 1, comprising:high-current-conductivity segments between and connected to grounded annular axial magnetics poles, including small radial spaces between the segments, for intercepting EMI from PWM voltage applied to the axial electromagnet coils. 30. The EMI shielding means in claim 1, comprising:high-current-conductivity segments around each radial electromagnet coil, connected to ground and to respective radial electromagnet cores, including small insulating spaces between the segments, for intercepting EMI from high-frequency components of PWM voltage applied to the radial electromagnet coils. 31. The EMI shielding means in claim 1, comprising:a high-current-conductivity annular member affixed to and concentric with the rotor assembly, and connected to other concentric conductors affixed to the rotor assembly, juxtaposed with two fixedly positioned high-conductivity annular members, one connected to the negative signal input of a high-bandwidth amplifier, whose positive signal input is connected to signal ground, and whose output is connected to the second annular member, for suppressing EMI in the rotor assembly by capacitive EMI detection and rejection. 32. The EMI shielding means in claim 2, comprising:high-magnetic-permeability annular steel, for providing closed magnetic flux paths for the rotor magnets, through the rotor angle sensors, for preventing this rotating peripheral flux from cycling stator material, and for suppressing magnetic fields from current in the stator conductors from reaching the rotor angle sensors. 33. The EMI shielding means in claim 2, comprising:high-current-conductivity segments between and connected to grounded annular axial magnetics poles, including small radial spaces between the segments, for intercepting EMI from PWM voltage applied to the axial electromagnet coils. 34. The EMI shielding means in claim 2, comprising:high-current-conductivity segments around each radial electromagnet coil, connected to ground and to respective radial electromagnet cores, including small insulating spaces between the segments, for intercepting EMI emanating from high-frequency components of PWM voltage applied to the radial electromagnet coils. 35. The EMI shielding means in claim 2, comprising:a high-current-conductivity annular member affixed to and concentric with the rotor assembly, and connected to other concentric conductors affixed to the rotor assembly, juxtaposed with two fixedly positioned high-conductivity annular members, one connected to the negative signal input of a high-bandwidth amplifier whose positive signal input is connected to signal ground, and whose output is connected to the second annular member, for suppressing EMI in the rotor assembly by capacitive EMI detection and rejection. 36. Axial servo electronics as in claim 2, including:current rectifier and filter means, connected to respective sensor electrodes, for removing the high-frequency component from the signals provided by the sensor rings;differential amplifier means, for providing two amplified signal pairs, responsive to the rotor assembly radial position and excursion rate;operational amplifier means, for providing pairs of outputs to respective axial servo PWM electromagnet coil drives, proportional to the difference between the amplified opposing signals and excursion rate, and the output of an integrator;said integrator, responsive to the difference of current in the two coils. 37. Radial servo electronics as in claim 2, including:current rectifier and filter means, connected to respective sensor electrodes, for removing the high-frequency component from signals provided by the sensor electrodes;differential amplifier means, for providing two amplified signal pairs, responsive to the rotor assembly radial position;operational amplifier means, for providing pairs of outputs to respective radial servo PWM electromagnet coil drives, proportional to the difference between the amplified opposing signals and excursion rate, having a prescribed dead-band;differential amplifier means, responsive to a force command signal and to output from an associated force sensor, for driving one of two associated radial electromagnets, to apply a radial force at one end of the rotor assembly, while an equal and opposite radial force is applied to the other end of the rotor assembly by a like radial servo, to cause precession torque. 38. Mechanical backup bearings as in claim 2, near each end of the rotor assembly, each bearing also including:a ball bearing having a fixed outer race and a rotatable inner race, and a plurality of load-bearing balls therebetween, which roll in contact with the inner and outer race;separators between each of the balls, formed from thin-wall tubing of a spring material, each having a neck at its center to maintain rolling contact with two balls, and having necks near both of its ends for maintaining rolling contact with idler races;outer idler races at both sides of the bearing, to provide outer raceways for the necks of each separator near their respective ends;inner idler races at both sides of the bearing, to provide inner raceways for the necks of each separator near their respective ends;axial grooves along the inner circumference of the inner idler race, to increase its radial compliance during assembly;a cover at each side of the bearing, each having a radially rigid inner shoulder to stiffen the adjoining inner idler race;means for affixing the covers to the outer race of the ball bearing. 39. A combination of the flywheel systems recited in claim 1, each having power interface electronics connected in parallel with like systems to a DC power buss, for providing a combined system having total power and energy capacity equal to the sum of the power and energy capacities of the connected systems. 40. A combination of the flywheel systems recited in claim 2, each having power interface electronics connected in parallel with like systems to a DC power buss, for providing a combined system having total power and energy capacity equal to the sum of the power and energy capacities of the connected systems, and for exchanging power between the connected systems.