GB2224398A - Generator/motor combination with high density magnetic fields - Google Patents

Abstract

The invention is for rotating electric machine including a means driven by the principal apparatus and coupled directly or indirectly, for example by a Simms coupling or a belt drive, thereto, specifically for supplying the requisite electrical energy to the driving portion of the machine. High density magnetic fields are provided, in most cases there being a critical such field flux density level requirement to enable the machine to function effectively. In for instance the generator mode, the output current is electrical energy generated surplus to the input requirement of the machine.

Description

Electric motors and generators.

According to conventional electrical theory concerning electric motors a back e.m.f. (electromotive force) is generated in the windings of such machines during their working. This e.m.f.

varies as the speed of their rotors and opposes the current supply to the windings, so that when running under no load conditions at a higher speed a reduced electical input is used.

When working under load the motores slow down, the back e.m.f.

generated is lowered and the current input increases to cope with the load.

Considering a D.C. motor example having a permanent magnet stator and an iron cored rotor and armature, the action of the armature coils rotating in the flux field of the stator magnet induces, after the manner of a dynamo generating current, a back e.m.f. in said coils. This back e.m.f. increases with the speed of the rotor and its armature coils. Obviously the back e.m.f.

generated in the armature windings depends also on the strength of the magnetic field produced by the stator magnet, and the required current supply to the armature windings rotating in a high energy magnetic field might be expected to be less than that necessary to supply the armature windings where the magnetic field of the stator magnet is of lower power.

Furthermore, it seems reasonable to suppose that even under full load working conditions this may apply.

In consequence of the lower current consumption of an electric motor of the D.C. kind envisaged having a more powerful stator magnet, theoretically, by increasing the magnetic field density of said stator magnet sufficiently it should be possible to obtain a higher mechanical power output from said motor than the electrical energy input needed to drive it, and by coupling the motor to a (D.C.) generator it could generate its own current supply and power for external utilization.

The theoretical hypothesis outlined above is not necessarily contrary to accepted physical laws since a change, such as a fall in temperature or a modification of the physical state/structure of the motor's stator magnet or/and armature core, either of a transient or a permanent nature, may occur during the running of such a motor and explain the difference in its energy input and output. A fall in the temperature of the stator magnet for example would result in the conduction of heat (energy) to it from the ambient atmosphere.

An excess of electrical energy might be produced by the D.C.

generator and utilized remotely, or the unit could function exclusively as a D.C. gernator.

This invention is for an electric motor, generator or a combined such motor and generator including a means driven by the principal apparatus and coupled directly or indirectly, eg. by a Simms coupling or a belt drive, thereto, specifically for supplying the requisite electrical energy to the driving portion of the machine.

If a stator magnet off the trapped fieldsupercond'ucting kind is- used (which:is contemplated) a much greater power. output-could ba-a-chieved.-- It:-i;s Further intended to replace the stator magnets .desribed by 'a high - power electromagnet system or-a combined such 'magnet arrangement, prefereably of superconducting design, but-the efficiency-obtainable may or may not then -be--so high.

In another arrangement the current supply to the armature windings is alternating. In this way the usual commutator may be dispensed with and slip-ring contacts provided.

Alternatively, an intermittent direct current supply to the armature windings is provided, after the manner disclosed in my U.K. patent application No. 52263/1976.

Then invention is moreover applicable to embodiments incorporating a rotary magnet and a stationary armature, either an A.C. or a D.C. supply to the windings of said stationary armature in this case being featured, although a means to effect the rythmic reversal of said D.C. supply to said windings may be required.

A means to rotate the rotor of the apparatus during the starting phase is usually required and could comprise a coupled electric separate starting motor (similar to an ordinary motor vehicle starter device) or the generator supplying current to the armature windings could be supplied with electric current derived from any suitable source, such as a battery, and function as a motor rotating said rotor during said phase.

Relating to the attractive and repulsive forces exerted by eg. a permanent magnet on another magnetic object in its vicinity, these forces do not in themselves constitute energy, however if motion between said objects is induced by said forces energy is generated and this energy must derive from some source viz. it is not created, (in conformity with the law of the conservation of energy), as I have in the foregoing description defined.

All magnets and magnetic objects may thus act directly or indirectly as an energy source, to a more or less extent.

A final arrangement obtains the current supply to its armature windings, ie. of the driving portion of the apparatus, internally as is disclosed in my U.K. patent specification number GB 2132420 A.

This last arrangement includes a provision to reduce the specific electrical energy consumption of the magnet, which is an electromagnet or a combined unit, and the increase in the strength of said magnet's flux is basically relative or partly so to the electrical energy consumed.

Control of the power output is effected by regulation of the current supply to the driving apparatus.

The modification of the physical state or structure, eg. of a permanent magnet stator or rotor, accounting for the apparent difference in the power input and output of embodiments might also be atomic or molecular, crystalline, or an alteration of the domain pattern of said magnet.

The factors relating to permanent magnets and magnetic objects could equally apply to ordinary or superconducting electromagnets and to stored field superconducting magnets employed.

Stored (trapped) field superconductors are preferably energized by pulse generator means. Their flux levels may also be varied by similar means, thus varying the power output. Likewise, a such means could energize or vary the magnetism of a permanent magnet stator or rotor, through a pattern coil.

Manual rotation of the rotor during the starting phase is practical, as is automatic control of the power output by a governor of any chosen design, such as an ordinary mechanical or magnetic unit, acting to operate a rheostat, for example, placed in the current supply circuit.

No reduction in the total energy output of embodiments would be experienced due to the use of a more powerful magnet and the lower current input, on the contrary, the total energy produced would not diminish but would increase owing to the greater magnetic field strength.

For convenience, either the stator or the rotor assemblies will hereafter be referred to as the magnet incorporating devices, or as said magnet.

According to one aspect of the invention there is provided a rotating electrical machine comprising a rotor and a stator, either of these assemblies forming a magnet incorporator, and constructed to allow the rotation of said rotor, magnetic means to induce said rotor rotation, a provision, ie. a comparatively high magnetic field density, to ensure a greater mechanical power output from said rotor than the electrical energy input to induce its rotation, and a means driven or actuated by said apparatus to generate said electrical energy input.

According to another aspect of the invention, the electrical energy input is D.C., A.C. or an intermittent D.C. supply.

According to a further aspect of the invention, a mechanical or/and electrical power output is derived from the apparatus.

According to a fourth aspect of the invention, the magnet is either a permanent or trapped field superconducting unit, an electromagnet of ordinary or ordinary superconducting kind or a combined permanent and electromagnet.

A reduced current consumption is achieved in electromagnets by methods such as the use of magnet cores of a higher permeability, viz. easily magnetized:, thus producing an effective increase in the magnetic field strength of said magnets relatis to;; to-said current:consumpvion.Alternatively, the winding density-of such magnets is increased with low temperature operation (to -maintain- a'- costnt--eIectrica1 resistance in the windings) or- superconductive working or the employment of a more conductive winding material, to obtain a greater magnet field strength, combined: such: methods also being used.

Combined electric motors and generators include generators or generator systems of a greater power output than that needed to supply the motor side of the apparatus with electric current, such plants in accordance with the present invention producing a surplus of either D.C. or A.C. electricity, depending on their manner of working.

The invention may be applied to a variety of kinds of electric motors and motor/generators, not merely to such machines of particular design, the essential factor being to employ a configuration in which the mechanical power output of the plant exceeds the electrical energy input by the generator or generator system or, conversely, wherein the electrical energy input by said generator or system is less than said mechanical power output. Motor/generator embodiments are of two kinds, those which function exclusively as current generators and those which produce both mechanical power and electric current for external utilization.Superconductive working is clearly preferable where practical, but ordinary permanent magnets, electromagnets or combined such magnets may be used, providing the magnetic field produced (in relation to the overall internal current consumption in eg. electromagnet using machines) is sufficiently intense. Examples receiving an intermittent D.C.

to energize their motor windings reduce their internal current consumption further by this novel means. Whatever the kind of plant, it may be utilized in fixed or portable form in any stationary or mobile installation.

The invention will now be described with reference to the figures of the accompanying drawings, which are purely diagrammatic representations of specific electrical machine embodiments and systems.

Referring to these drawings: The dipole permanent magnet electric motor illustrated comprises a permanent magnet stator 1 (Fig. 1), a rotor 2, a commutator 3 and a D.C. generator 4. The rotor 2 has a soft iron core around which said rotor's energizing coils are wound in series connected fashion, the two ends of these coils being electrically connected to the contact shoes, two in number, of the commutator 3 whereon two brushes 5, connected electrically to the generator 4, bear. The generator 4 is driven by the rotor 2 via its, said rotor's, spindle, said rotor revolving in a clockwise direction.

The poles of the magnet 1 and the rotor 2 are aligned in the drawing and, when in this position, generator 4 passes current momentarily by way of brushes 5 and commutator 3 to the windings of said rotor, the poles of which are then repelled by the poles of said magnet, ie. by their magnetism which is of the appropriate polarity, and said rotor is induced to revolve in the direction indicated.The current supply to the windings of rotor 2 is interrupted by commutator 3 before said rotor revolves through an angle of 90 degrees, however the current flow through said windings still tends to continue due to self induction and this tendency is encouraged by the provision of a short circuit (not shown) connecting, through a condenser which absorbs said current, the ends of said windings, so that said rotor is induced, despite said current supply interuption, to rotate further until its poles pass said angle, whereupon said rotor poles are attracted by the poles of magnet 1 towards which they are moving and said rotor and magnet poles again align, after which the working cycle described is repeated, no current being passed to said rotor windings during said attraction period.

The short circuit provided in the windings of rotor 2 is a desirable but optional inclusion.

The magnet 1 is of U profile, but the use of a permanent magnet of some other kind, such as a cylindrical ring dipole unit (shown by the broken line 6) is practical, as is the substitution of a combined permanent and electromagnet, an electomagnet having a high winding density and working at a subatmospheric temperature (to obtain a high magnetic field strength), or a trapped field superconducting cylindrical magnet for said magnet 1.

A combined on-off switch and rheostat 7 regulates the power output of the motor and also acts, breaking the current supply circuit, wherein it is interposed, of rotor 2, to stop said motor's working cycle. The automatic control of the device 7 eg. by a mechanical or magnetic governor, with a manual override, is proposed.

The motor is started, for example , by supplying current (D.C.) to the brushes 5 from a battery.

Because of the intermittent nature of the current supply to the rotor windings and the back e.m.f. generated in them, little current is used and the generator 4 requires only a minimum of power to drive it.

To help obtain an even torque from the rotor 2 a flywheel may be incorporated on its spindle, although devices, such as fans and airscrews driven thereby, can act as said flywheel provision.

to compliment tha: attraction- of- th-e rotor poles by the:- magnet poles, in a refinement, current is also conducted"fr'om' -gnerator 4 momentarily to the rotor w1ndxngs at ox a'fte"' the 'beginnig- of: the, attraction period of the rotation of rotor 2 by additional commutator contact shoes 8 Fig. 6. - - Instead of the 'permanent' magnet stator" 1- Fig. l-a wound stator may be embodied, the rotor 2 incorporating the permanent magnet for example in this modificaiton.To obtain rotation of the magnet rotor, in this instance, the windings of the stator may require to be supplied with A.C. electricity by generator 4 and a means to interrupt this current flow during said rotor's rotation would be necessary, or at least preferential.

Referring to Fig. 2, in one such mode of working the generator 4 is an A.C. unit supplying current intermittently to stator windings 9 via side placed brushes 5 and commutator 3, the circuit through said brushes being periodically made and broken during the rotation of the rotor by said commutator's contact shoes, thus interrupting said current and providing the intermittent supply to said windings. The motor constitutes an A.C. unit, of course.

A short circuit through a condenser 10 across the ends of the stator windings 9 Fig. 2 is an optional provision designed to help damp current voltage fluctuations caused in said windings by the making and breaking of their circuit by the commutator 3, which is of the same construction as the like device 3 Fig. 1 and reduces the current consumption by said windings in a similar manner to that, broadly speaking, used by the first example to obtain the further reduction in current usage by its rotor, that is by energizing said windings briefly only during the repulsion phase of the rotor poles by the stator poles.

A dipole rotor magnet and stator is also employed by this second example and is the more simple and effective arrangement.

Surplus electric current may be conducted from the generators 4 Figs. 1 and 2 for external utilization. Alternatively, said surplus current is stored in eg. a battery, such as the battery used to supply D.C. electricity to the rotor windings of the first example when starting this example's working cycle, a.hd supplies the windings of the main apparatus during their momentary periods of current usage. With this design it is practical to reduce the size of the generators 4 and the energy consumed in driving them.

A battery equipped circuit giving a constant surplus current output (which surplus current would otherwise be intermittent in character) is additionally projected.

A resistor replaces condenser (capacitor) 10 Fig. 2 (or the like) in chosen Fig. 1 and Fig. 2 embodiments.

The generator 4 desirably should be capable of starting automatically and delivering current to the rotor or stator windings under the load or no load working conditions prevailing, and to this end I suggest that a hybrid permanent-cum-wound (electro) magnet such generator is the most suitable unit.

A third example (Fig. 3) comprises a trapped field superconducting cylindrical stator magnet 1 having pattern coil electromagnets 11 disposed each side of it and energized by a pulse generator 12, a dipole rotor 2, a commutator 3 and its brushes 5, and a D.C. generator (not shown) coupled directly to the spindle of said rotor.

When starting the working cycle of this third example a very strong pulse of D.C. electricity is passed by the generator 12 to the winding coils of the electromagnets 11. This current magnetizes the soft iron cores, the inner ends of which are located close to but not contacting the periphery of cylinder 1, of said electromagnets 11 and thus also imparts a dipole magnetism to said cylinder 1, which is first cooled to a superconductive state and is of a suitable material and arranged to allow this cooling. The magnetism imparted to the cylinder 1, due to said cylinder's superconductivity, is trapped therein and persists even after the period of the current pulse passed to the electromagnets 11.

Thereafter, current is conducted to the windings of rotor 2 via brushes 5 and commutator 3 intermittently, ie. only during the repulsion phases of said rotor's poles by the poles of magnet 1 (actually eg. during 90 degrees of said rotor's clockwise rotation to its position shown in the drawing), from the D.C.

generator driven by said rotor through its coupling to the spindle thereof and from a storage battery incorporated in said rotor's supply circuit conducting the current to said windings, and the continuous rotation of said rotor in said direction is effected by the alternate repulsion and attraction of its poles by the poles of magnet 1.

If desired, the rotor 2 may act as the trapped field superconductive magnet; in this instance, the stator system described with reference to Fig. 2 and the second example is embodied.

Various methods of cooling the stator cylinder 1 and, in the relevant instance, the rotor (2) magnet, which may also be cylindrical, such as the use of a hollow construction or an internal spiral passageway or a jacket fed with a circulating or vaporizing cooling liquid, are considere practical.

The gap provided between the inner ends of the cores of the electromagnets 11 and the periphery of cylinder 1 reduces heat conduction to said cylinder from said electromagnets.

The-magmetic field trapped in cylinder '1 is varied in intensity, qu:enched. or- -revrsed jn polarity (hence reversing the direction of; rotation-or rotorz2), in selected instances, by passing a -current: pulse - in ,.the K reverse- .di'recio,n, relative to the direction of. the first current pulse, through- the windings of the electromagnets 11, the generator 12 having this capability and being so .used..

Since no current is passed by commutator 3 to the rotor winding.

during the attraction periods of the poles of said rotor, the current consumption, compared with that of a D.C. electric motor of conventional design, of this example is halved without indcurring a corresponding equal fall in the power available from said rotor, and the use of a lower output rotor (2) driven D.C. generator, as a consequence of said decreased current requirement by said rotor windings, being possible, any actual torgue loss at the rotor shaft due to the intermittent current use stated probably thereby is also compensated for. The use of the superconductive magnet (1) ensures a very high back e.m.f.

in the rotor windings and, even during the "current off" attraction periods of the rotor poles by said magnet constant high rotor torque.

The electromagnets 11 are positioned diametrically opposite each other and may need to be pulsed by generator 12 several times to establish the magnetic field pattern in cylinder 1. Once however cylinder 1 is fully magnetized, the pulse generator 12 is switched off and uses no further current, except perhaps when later required to quench or alter the intensity of said magnetism, for example.

Surplus current can be passed from the rotor windings' supply circuit for external utilization, a rotor driven D.C. generator having an increased current output being necessary, in this case.

Another method of reversing the direction of rotation of the rotor 2 consists in the reversal of the current flow through the windings of said rotor by means of an ordinary reversing switch optionally interposed in the current supply circuit of said windings. The action of the apparatus in either instance during the said reversal of rotor 2 would be different, in that current would be passed to said rotor's windings by commutator 3 during the attraction periods of its, said rotor's poles.

The reversal of rotor 2 is avoided in a preferred method, by the inclusion of a drive from said rotor through a coupled reversing gearbox, which might also be adopted to give a variable speed drive.

The pulse generator, in practice, derives its current supply from any convenient source, such as the mains or the storage battery, current from which is supplied to the windings of rotor 2 to start said rotor's rotation and steady the load on the D.C.

generator also supplying said windings, during continuous working conditions (and which battery is continuously recharged by said D.C. generator during the intermittent off periods of said rotor windings' current-supply) referred to previously, and at 12 Fig. 3 is an electronic unit bascially comprising a high voltage generator and a condenser store.

Arrangments in which the rotor 2 is modified to include a three pole construction or, conversely, in which said rotor incorporates the dipole superconducting trapped field cylindrical magnet and the stator embodies three or any greater odd number of poles energized by windings alternately fed with current by the rotor driven D.C. generator, via an electronic timer and distributor for example, so as to induce said magnet equipped rotor's rotation, would give a more even rotor output torque. The said rotor magnet could include an internal pattern field coil or an external such coil system, eg. said stator pole where large in number, supplied with current by pulse windings 12 may magnetize the rotor magnet.

generator The superconducting A.C. electric motor or generator illustrated in Fig. 4 includes a permanent magnet dipole rotor 2, a cylindrical laminated soft iron stator 1 energized by two superconducting electromagnets 13 placed on diametrically opposite sides of said stator, and an A.C. generator 4 driven by a belt 14 from a pulley fixed on one end of the spindle of said rotor. The electromagnets 13 have high density coil windings supplied with A.C. electricity by generator 4 and induce an alternating dipole mangnetism in stator 1, which is thermally insulated from the inner ends of said magnets 13 by air spaces; hence inducing the rotation of the dipole rotor 2. If desired, the rotor 2 may comprise a trapped field superconducting dipole magnet or/and have a large number, such as four, six or eight, magnets poles.The electromagnets 13 are cooled by liquid coolant circulating through or vaporizing in the hollow interiors of their cores. The high back e.m.f. induced in the windings of magnets 13 during continuous working, by the rotor 2, decreases the current requirement of said magnets and thus the power required to drive generator 4 under either load or no load conditions.

Alternating current is best supplied to the electromagnets 13 from a convenient source, such as the A.C. mains, when starting the plant's working cycle, but alternator 4 might be driven by a battery fed D.C. auxiliary electric motor during said period to supply said current, said alternator's main drive by belt 14 being through a freewheel device to allow this latter method of starting the motor/generator. Rotor 2 is driven, possibly through a speed reducing gearbox or/and a freewheel assembly, by an auxiliary electric motor during said starting period, in another starting method.

The release of energy from the very powerful amperian current loops known to exist in all magnetic matter could, theoretically, provide the energy quantity in excess of that requisite to energize magnets 13.

An increase in--the prmeabii;jty ot th'e material of, for example stator 1,. may furtlier -'reduce' *he specific current nonsumption, ie. relative to the' magnetism produced in- said stator, of magnet's , '13 and give an enhanced 'u"se'ful 'power, output.

With reference to the electric motor-cum-generator shown in Fig.

5, a thin walled cylindrical stator 1 is alternately given a dipole magnetism of one kind and then the opposite polarity at regular intervals by two electromagnets 15, thus inducing the continuous rotation of a rotor 2 which is permanently magnetized in dipole fashion and also is of cylindrical profile. The magnets 15 are energized intermittently by an electronic pulse generator 12 supplied with D.C. electricity by a dynamo-generator 4 driven directly by the spindle of rotor 2, the permeability of the stator cylinder 1 being designed for optimum retention of magnetism between each current pulse, which is of very brief duration, to the magnets 15 giving said cylinder its dipole alternating magnetism.Before starting the machine a pattern field coil (not shown) enclosed in rotor 2 is pulsed with direct current, to magnetize said rotor, by the device 12, which also has this ability, and said rotor retains this magnetism indefinately.

In one mode of working the rotor 2 Fig. 5 is an ordinary permanent magnet. In higher powered working mode said rotor 2 is a superconducting trapped field magnetic assembly.

The thinness of the stator 1 Fig. 5 lowers said stator's resistance to the intermittent reversal of its magnetic polarity, and thus the current usage, in this process, by the electromagnets 15.

The stator 1 Fig. 5 is supported by an outer cylinder of laminated soft iron construction, in a refined arrangement, or is attached thereto, eg. by brazing, or is merely a coating or plating on the inner surface of said supporting cylinder, which is hollow in actual form. The rotor magnet 2 optionally is also a similar basic assembly, but with its supporting cylinder placed internally in the composite structure.

The various features of the particular examples described may be interchangeable; for example, the embodiement shown in Fig. 3 can incorporate a permanent magnet stator instead of the superconducting unit 1.

A typical construction practical for the superconducting stored field magnets is disclosed in U.K. patent specification No.

1586031.

The embodiments described with reference to the drawings are non-limitative examples of electrical machines in accord with the invention and including constant polarity magnets of permanent or stored field kind.

From the foregoing dissertation it will be appreciated that the invention concerns not only the use of high field magnetics but also a variety of methods of otherwise reducing the internal electrical consumption of the several basic mechanisms, largely based on the electrical energy usage of their individual parts, either actual or relative to the produced power at the rotor shaft and economy therein.

The generator 4 Fig. 1 also passes current to the windings(s) of magnet 1 of said figure, in the appropriate examples, viz.

having a modified stator.

Claims (7)

Claims"

1. A rotating electr-ical:machine comprising a rotor-and a stator, either of. these assemb1ies,:fopin -a magnet incorporator, and constructed to allow-the rotation of said rotor within the pole t'nnel M'f or at, Least in close working proximity to the poles of sa~ d stator, magnetic means to induce said.rotor rotation, a provision, ie. the use of a comparatively high::magnetic field density, to ensure a greater mechanical power output ;from said roter than the electrical energy input manifesto to 'induce its rotation, and a means driven or actuated by said apparatus to generate said electical energy input.

2. An electrical machine in accord with Claim 1, wherein the electrical energy input is A.C., D.C. or an intermittent D.C.

supply, said machine being designed to accept such current.

3. An electrical machine in accord with Claims 1 and 2, wherein a mechanical or/and an electrical power output is derived from the apparatus.

4. an electrical machine in accord with Claims 1, 2 and 3, wherein a magnet assembly consisting of either a permanent or a trapped field superconducting unit, an electromagnet of ordinary or ordinary superconducting kind or a combined permanent and electromagnet is embodied, said magnet assembly providing magnetic flux reacting, during said machine's working cycle, with the magnetic field of an incorporated wound armature, to effect the rotor rotation.

5. An electrical machine in accord with Claims 1 to 4, specifically as described with reference to the accompanying drawings.

6. A rotating electrical machine designed, constructed and working substantially as hereinbefore described with or without particular reference to the several figures of the drawings.

7. The method of power generation employed by electrical machines in accord with the preceding Claims.