WO1993015929A1

WO1993015929A1 - Electrical current pick-up from a surface conductor array

Info

Publication number: WO1993015929A1
Application number: PCT/AU1993/000064
Authority: WO
Inventors: Ernest Dennis Workman
Original assignee: Ernest Dennis Workman
Priority date: 1992-02-14
Filing date: 1993-02-15
Publication date: 1993-08-19

Abstract

A stationary array of conductors (10) is arranged to constitute a contact surface. A mobile object or vehicle such as a trolley bus is fitted with a pick-up shoe (18). The pick-up shoe (18) is adapted for sliding, rolling or stationary contact with the conductors (10). The pick-up shoe (18) comprises a number of contact segments (12). Each contact segment (12) can only contact one stationary conductor (10) at any given time. The contact segments (12) shall be sufficient in number and arranged so that at least one contact segment shall be in contact with a stationary conductor of one polarity and at least one contact segment shall be in contact with a stationary conductor of the other polarity. A pair of rectifiers (19) is connected to each contact segment (12) to conduct from the respective segment (12) to positive and negative busbars (16) and (17).

Description

ELECTRICAL CURRENT PICK-UP FROM A SURFACE CONDUCTOR ARRAY FIELD OF THE INVENTION The following invention relates to an electrical current pick-up. More particularly, though not exclusively, the invention relates to a device to provide continuous electrical supply and return circuits through a sliding or rolling interface, so that a mobile object may collect electrical energy from anywhere on the contact face of a stationary object.

PRIOR ART Electrical energy is often utilised to drive vehicles. For example, trains and trams receive electrical energy from overhead lines and are grounded by wheels to tracks upon which the train or tram is guided. Clearly, trains and trams are limited to motion along the line of the track. Trolley buses on the other hand, although not grounded by wheels to a track have limited lateral transfer capability determined by the length of the poles connecting the trolley bus to overhead wires. As an additional disadvantage, since the trolley bus is physically connected to the overhead lines, it is not possible for one trolley bus to pass another whilst connected to the same line.

Amusement park bumper cars receive electrical current from an overhead net and are grounded to a metal surface over which the bumper cars ride. Clearly, the provision of a metallic surface over a substantial distance of a roadway for example would be expensive and impractical.

OBJECT OF THE INVENTION It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages.

DISCLOSURE OF THE INVENTION There is disclosed herein an apparatus for conducting electrical energy from a stationary array of conductors to an object which may move relative to said conductors, comprising: pick-up means comprising a plurality of contact segments, each adapted to contact one of said conductors at a given time, a pair of terminals at each contact segment, current output means, and circuit means interposed between said terminals and said current output means to provide a selected form of electrical energy at- said current output means.

Preferably, the circuit means comprises a rectification means or a controlled rectification means.

There is further disclosed herein an apparatus for conducting electrical energy from stationary conductors to an object which may move relative to said conductors, comprising: a pick-up shoe comprising a plurality of contact segment assemblies, each contact segment assembly comprising a main contact segment and an auxiliary contact segment electrically insulated from the main contact segment, each contact segment assembly being adapted to contact one of said stationary conductors at a given time, current output means, control means interposed between said auxiliary contact segment and said current output means, and circuit means interposed between said main contact segment and said current output means being controlled by said control means to provide a selected form of electrical energy at said current output means. There is further disclosed herein an apparatus for conducting electrical energy from an array of conductors, each of said conductors being energised at a different potential from adjacent conductors, the apparatus comprising: pick-up means comprising: an array of contact segments, each contact segment being adapted to contact one, and only one, of the energized conductors at a given time, each contact segment comprising one or more terminals, the quantity of segments and the location of each of said contact segments in the array of contact segments being such that, at any given time, and for each different conductor potential, there shall be at least one contact segment conducting from the conductor, a current output means, and a circuit means interposed between said contact segment terminals and said current output means to provide a selected form of electrical energy at the current output means for a given form of electrical current input.

Preferably, said circuit means comprises controlled rectification means. Preferably, each contact segment comprises a single plate of electrically conductive material. Such a preferred configuration would be suitable for an installation wherein said stationary conductors comprises an AC or DC input. Typically, providing that continuous electrical contact is maintained, arcing should not occur since the contact segments successively make and break contact with the stationary conductors because an alternative path of low resistance is available.

Alternatively, each contact segment may comprise a main contact segment being connected to one of said pair of electrical connections, and an auxiliary contact segment connected to the other of said pair of electrical connections. Such a configuration would be suitable for an installation wherein said stationary conductors comprise an alternating current input. Typically, the stationary conductors would comprise a plurality of uniformly spaced parallel conductors suspended above a roadway or factor floor for example. Adjacent conductors would typically be of alternate polarity. A vehicle to which the above disclosed apparatus is attached may traverse a ground surface below the suspended conductors and move in a direction along the path of said conductors, across the path of the conductors, or indeed in any direction below the conductors. It should be appreciated in this regard that such a vehicle may ride upon a non-conductive surface as no grounding electrical contact is required between the vehicle and the surface upon which it rides. All manner of road vehicles for example may be powered by electrical energy from an external source.

There is further disclosed herein a system comprising a plurality of stationary conductors in combination with the apparatus described above. As an advantage of the apparatus disclosed above, it will not be necessary for a vehicle to carry large energy storage means such as batteries. Accordingly, the vehicle's mass may be reduced. Energy storage may then be situated in a suitable static location within the electricity generating/distribution system where it can be shared economically amongst many users, and where economy and efficiency of siz will enable load fluctuations to be minimised. DEFINITIONS As used herein, the following terms have the following meanings: "RECTIFIER" equipment for transforming AC to DC.

"INVERTER" equipment for transforming DC to AC. "CONVERTER" equipment for transforming AC to AC.

"DC CONVERTER" equipment for transforming DC to DC.

"CYCLOCONVERTER" equipment for transforming a higher frequency to a lower frequency AC without a DC link. "CHOPPER" a "single ended" inverter for transforming DC to DC or DC to AC. The term "rectifier" is defined in the broader sense as any device which presents a different resistance to the flow of an electrical current when the direction of the current is reversed. BRIEF DESCRIPTION OF THE DRAWINGS

Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings wherein:

Fig. 1 is a schematic view of stationary conductors and a pick-up shoe including a circuit diagram, Fig. 2 is a further schematic elevational view of the conductors and pick-up shoe of Fig. 1,

Fig. 3 is a schematic plan view of a pick-up shoe, Fig. 4 is a schematic elevational view of a further embodiment of the invention comprising stationary conductors, and an alternative pick-up shoe employing SCR's connected to the main contact and controlled by an auxiliary contact,

Fig. 5 is a schematic plan view of an arrangement of contact segments on the pick-up shoe depicted in Fig. 4,

Fig. 6 is a schematic plan view of an alternative arrangement of contact segments on a pick-up shoe, being a refinement of Fig. 3, Fig. 7 is a schematic plan view of an arrangement of contact segments on a pick-up shoe intended for attachment to a vehicle which travels along a fixed path, more or less along the line of the stationery conductors, Fig. 8 is a schematic elevational view of stationary conductors and a pick-up shoe including an alternative circuit diagram, Fig. 9 is a schematic elevational view of stationary conductors an a pick-up shoe including yet a further alternative circuit diagram, and Fig. 10 is a schematic perspective view of a plurality of overhead conductors suspended by a support network. The apparatus shown in Fig. 1 may operate in the following modes:-

(a) As a rectifier by transforming an AC input to a DC output.

(b) As a DC converter by transforming a DC input to a DC output. The apparatus shown in Fig. 4 is intended to operate primarily as rectifier by transforming AC input to DC output. The apparatus shown in Fig. 8 may operate in the following odes:-

(a) Primarily as a converter transforming an AC input to an AC output without a DC link using the trigger circuit shown.

(b) Using a different trigger circuit, as a cycloconverter transforming an AC input to an AC output of lower frequency without a DC link.

(c) Using a different trigger circuit, as a rectifier transformin an AC input to a DC output.

(d) As a DC converter transforming a DC input to a DC output usin the trigger circuit shown. (e) As an inverter transforming a chopped DC input to an AC outpu using the trigger circuit shown.

The apparatus shown in Fig. 9 may operate as a single phase AC converter operating on two phases of a three phase supply and transforming a three phase AC input to a three phase AC output. One of the phases is unchanged.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning initially to Figs. 1 and 2 of the accompanying drawings, there is schematically depicted a stationary array of conductors 10 arranged so as to constitute a contact surface. The mobile object or vehicle (not shown) comprises a pick-up shoe 18. The pick-up shoe 18 is adapted for sliding, rolling or stationary contact with the stationary conductors 10. The pick-up shoe 18 comprises a plurality of contact segments 12 arranged so that at least one segment 12 may be in contact with a particular stationary conductor 10 at any given time. There are sufficient segments 12 to enable some segments to always remain in contact with a stationary conductor 10. A pair of rectifiers 19 is connected to each contact segment 12. The pair of rectifiers 19 in an array 13 conduct from the respective segment 12 to positive and negative busbars 16 and 17. More than one set of rectifiers may be connected to a single set of contact segments, but special precautions may be required to prevent unwanted interaction as would be appreciated by the skilled addressee.

The stationary conductors 10 may be energised with either direct current or alternating current. The output of the rectifier is rectified direct current.

The apparatus herein is capable of maintaining continuous supply and return circuits from the stationary supply conductors 10 to the mobile load via the combination of moving pick-up shoe 18 and rectifier array 13 in the following circumstances:-

(a) With the pick-up shoe 18 stationary, and in contact with the stationary supply conductors 10, and in any location on the stationary supply conductors, and in any orientation about an axis perpendicular to the contact surface, at the point of contact, between the pick-up shoe 18 and the stationary supply conductors 10.

(b) During linear motion of the pick-up shoe 18, along or across the stationary supply conductors 10, in any direction. (c) During rotation of the pick-up shoe 18, on the stationary conductors, about an axis perpendicular to the contact surface, at the point of contact, between the pick-up shoe 18 and the stationary conductors 10.

It should be appreciated that the invention herein may continuously transmit electrical energy, by contact, from a stationary object to one or more mobile objects, or in modified form from one or more mobile objects to a stationary object, in a way which provides freedom of movement to the mobile objects so that the mobile objects in any combination may independently traverse the entire contact surface of the stationary object in any direction, or rotate about an axis perpendicular to the plane of contact which the mobile object makes with the stationary object (conductors 10) at the point of contact or a combination of rotation or traversal .

The stationary conductors 10 may be wires, studs, strips or plates spaced at a set minimum pitch from one another. Such minimum pitch, that is the distance or air gap between adjacent conductors or studs or plates, is always to be greater than the maximum dimension or diameter of contact segments 12 on the pick-up shoe 18, so that short-circuiting between adjacent conductors will not occur.

All stationary conductors 10 shall be energised from a direct current source or from an alternating current source. The direct current source may be continuous, pulsating or chopped whereas an alternating current source may be single phase or polyphase. Adjacent stationary conductors 10 shall be of different polarity from one another.

Electrical contact between the pick-up segment 12 and stationary conductor 10 must cease before contact with any other stationary conductor 10 occurs. Each contact segment is connected to a corresponding one of rectifier pairs 19. It is possible however to have more than one rectifier set connected to a single set of segments.

In order that a circuit, from the stationary conductors 10 through a moving pick-up shoe 18 may continuously exist irrespective of the position or rotation of the pick-up shoe 18 on the stationary conductors 10, a sufficient number of contact segments 12 is to be provided so that at least two contact segments will be in contact with two respective stationary conductors 10, the two conductors 10 being of different polarity.

The rectifier array 13 will comprise at least one pair of rectifier devices 19 for each contact segment 12. Each pair of rectifier devices 19 is to be connected to one contact segment 12. Each rectifier device 19 of the pair shall exhibit a rectifier action. The rectifier action may be achieved by use of a diode, an SCR, a transistor or a switch and control circuitry to achieve the same result. The rectifier devices 19 of the pair, shall be connected so that one member of the pair conducts a current from the contact segment 12 to the positive rectified current busbar 16 and the other member of the pair 19 conducts from the negative rectified current busbar 17 to another contact segment 12.

In use, a contact segment 12 of pick-up shoe 18 slides or is otherwise positioned into contact with a positively energised stationary conductor 10. The segment becomes positively energised to me potential of the stationary conductor 10. The positively energised contact segment 12 conducts a current through one semi-conductor device 19 of the semi-conductor device pair connected to the segment 12, to the positive busbar 16 while the other semi-conejctor device 19 of the pair blocks the flow of electric current. At the same time at least one other contact segment 12 is in contact with a negatively energised stationary conductor 10. One semi-conductor device 19 of the semi-conductor pair attached to the segment 12 in question conducts forward from the load via the negative busbar 17 while the other semi-conductor device 19 of the pair, blocks the flow of electric current. The supply circuit is completed from positive stationary conductor 10 to contact segment 12, through the forward conducting semi-conductor device 19 to another contact shoe segment 12, to the negative stationary conductor 10. This process is repeated as successive contact segments slide, roll or otherwise make contact into and out of contact with the stationary conductors 10 energised at alternate polarities. Continuity of the electrical circuit is maintained by having a sufficient number of contact shoe segments 12 so that contact with the stationary conductors 10 of differing polarity is always maintained.

Turning now more particularly to Figs. 4 and 5, an alternative embodiment of the present invention is shown. In this instance, the pick-up shoe 18 comprises a main contact segment 20 and an auxiliary contact segment 21. The apparatus is suitable for particular applications. It should be appreciated that alternative types of pick-up shoe are required because of current, inductive load and motion constraints. The auxiliary segment 21 is introduced as a sensor to enable an SCR 23 to be turned off at zero crossing voltage if alternating current. For example switching the controlled rectifier 23 on while the main segment is in contact and off at zero voltage is provided for where the stationary conductors 10 are provided with an alternating current input. Accordingly, a minimisation of arcing between contact segments 20 and stationary conductors 10 is achieved when a segment 20 breaks contact. The pick-up shoe 18 in an alternating current system provides a plurality of auxiliary contact segments 21 within the boundary of the main contact segment 20 so that the controlled rectifier 23 can be triggered into a conducting state when the main contact 20 is energised by a stationary conductor 10, or out of a conducting state by providing the main contact 20 with a tail 22 of sufficient length so that the length of the tail 22 exceeds the distance travelled by the segment during a half wave of alternating current in the stationary conductors 10. The controlled rectifier 23 may be triggered into or out of a conducting state. A triggering control circuit is provided which senses the correct time to switch the pick-up shoe segment rectifier into and out of conduction. In Fig. 4, it should be appreciated that reference numeral 23 represents a silicon controlled rectifier and reference numeral 24 indicates a triac and a diode. The triggering control circui may be adapted to trigger the semi-conductor devices at a specific time and polarity so that rectified direct current is obtained at the output busbars. In Fig. 5 of the accompanying drawings, the distance A, representing the length of an auxiliary contact segment 21 is to be greater than the length travelled by the device in a half wave AC input. The length B is the distance travelled by the device (shoe) in a full AC wave. The distance C also corresponds to a length travelled by the device in an alternating current wave.

In Fig. 6 of the accompanying drawings, an alternative arrangement of contact segments is depicted. In this instance, each contact segment 21 is in the form of a three pointed star having an overall diameter "D" corresponding to something less than the minimum pitch of the stationary conductors 10.

Fig. 7 shows an alternative arrangement of contact segments 20 for application with vehicles which travel along a fixed path such as for example a train or tram. Each contact segment 20 being in the form of a angular strip is of a length "E" corresponding to something less than th minimum pitch of the stationary conductors 10.

Referring now to Fig. 8, a more elaborate embodiment of the electrical current pick-up is depicted. Such an arrangement has the capability of giving an AC output synchronised to the AC supply.

Four SCR's 23 are connected between each contact segment 12 and th output busbars 14. The gate of each SCR 23 is supplied from the supply to its cathode via a diode 81 and a triac 82 in series. The gate of eac triac 82 is supplied with a pulsating signal in synchronism with the supply frequency and delivered from the supply via a trigger circuit as shown. There are two trigger signals namely A and B. B is 180 electrical degrees out of phase with A. In each segment group triacs 82, and 82,_v are triggered into conduction by a positive A trigger pulse signal. Similarly triacs 82,, and 82,,, are triggered into conduction by a positive B pulse trigger signal . Group 1 contact segment is shown in contact with a phase A conductor 10. During the first 180 electrical degrees the gates of triacs 82, and 82,_v will be energised by A trigger but only triac 82, can pass a trigger signal to the gate of SCR 23,. Similarly, during the second 180 electrical degrees the gates of triacs 82,, and ^2,,, will be energised but only triac 82,,, can conduct a trigger signal to the gate of SCR 23^. SCR's 23,, and 23_JV do not conduct at any stage while phase A is available at the contact segment.

Group 2 contact segment 12 is shown in contact with a phase B conductor. During the first 180 electrical degrees the gates of triacs 82, and 82,_v will be energised by B trigger but only triac 82,_v can pass a trigger signal to the gate of the SCR 23,.,. Similarly, during the second 180 electrical degrees the gates of triacs 82,, and 82,,, will be energised but only triac 82,, can conduct a trigger signal to the gate of SCR 32,_j. SCR's 32, and 32,,, do not conduct at any stage while phase B is available at the contact segment.

Therefore, during the first 180 electrical degrees, a circuit exists from stationary conductor phase A to group 1 contact segment 12, through group 1, SCR 32,, to the output busbar "a" to the load, and from the load, to output busbar "b", through group 2 SCR 32,_v to the group 2 contact segment 12 and to stationary conductor phase B and, during the second 180 electrical degrees, a circuit exists from stationary conductor phase B to group 2 contact segment 12, through group 2, SCR 32,,, to the output busbar "b", to the load, and from the load to output busbar "a", through group 1, SCR 32,,,, to the group 1, contact segment and to stationary conductor 10 phase A.

When more than one segment group is in contact with phase A the load will be shared between the segment groups. Similar sharing will occur when more than one segment is in contact with phase B.

The circuit means for providing the trigger signals is as shown on Fig. 8.

This circuit derives a synchronous trigger signal from the rectified output of the auxiliary rectifiers. The ripple at twice the supply frequency is clipped by ∑ener diode 83 and squared by an inverter 4069a. The 2 x supply frequency of the inverted signal is then halved b means of flip-flop 4013a to correspond to the supply frequency. The signal from the frequency divider is inverted in an inverter 4069b and supplied to the base of an npn transistor 84. The emitter of transistor 84 enables the group 'A' triacs 82. The output of 4069b is inverted again in an inverter 4069c and supplied to npn transistor 85. The emitter of transistor 85 enables the group 'B' triacs.

A current or control means which performs a similar function may b substituted. An additional enhancement of Fig. 8 is shown in Fig. 9.

This circuit would be suitable in supplying 3 phase AC to rail guided vehicles such as trains/trams. The third phase is supplied to th running rails and is collected by the running wheels of the rail vehicle With reference to Fig. 10, a preferred support network for overhea conductors 10 is shown. In order to suspend the conductors 10 in a common plane, alternative conductors 10 are attached at 101 to support bridges 100. Support bridges 100 are formed in a stepped configuration to bridge alternative conductors 10 as shown. As an alternative, conductors 10 may be moulded or otherwise set into a continuous non-conductive sheet of plastics material or the like.

INDUSTRIAL APPLICABILITY The invention herein may be used as a means of transmitting electrical energy from a surface to appliances without using a flexible cord. This may be achieved from a surface, consisting of energised conductors separated by insulation to an appliance fitted with a pick-up shoe in contact with the surface stationary conductors. The appliance may be placed anywhere on the surface of energised conductors. Examples of such appliances would be electric irons, jugs, fans with universal motors, lamps or toasters, such appliances would have to operate at low voltage for safety reasons (typically 12V).

The invention herein may also be used as a means of supplying single phase AC or DC electrical energy to a street car, rapid transit car, electric locomotive, electric train without the need for the rails to be used in the return circuit. Alternatively, three phase AC may be supplied if the rails are used to supply the third phase.

The invention may also be used as a means of supplying electric energy to vehicles such as bicycles, motorcycles, cars, trucks, buses, semi-trailers, independently of the road surface and in some instances farm tractors. The invention may also be used to power toy and model representations of the above.

The use of the invention described herein would allow vehicles fitted with the pick-up shoe to freely traverse, anywhere within the limits of an overhead wiring system and overtake any other electric vehicle, similarly equipped, without being bound to a fixed route.

The use of the invention by road vehicles would permit vehicles so fitted to be powered from an energy source external to the vehicle, such as the electricity grid of power utilities. The invention provides a practical alternative means of powering vehicles with electric motors instead of internal combustion engines.

Furthermore, the invention herein may serve as a means of continuously supplying electrical energy to electrically powered vehicles such as forklifts, wheelchairs, hospital stretchers which have heretofore been battery powered.

The invention may also be used as a means of supplying electrical energy to vehicles involved in underground mining and haulage, as a means of supplying electrical energy to vehicular ferries traversing across rivers, to fun park "dodgem" cars and "scooter" boats, to mobile electrically powered lawn mowers, garden tools and appliances, as a means of supplying electrical energy to hand held tools by a person equipped with a harness carrying a pick-up shoe in contact with stationary supply conductors, and as a means of supplying electrical energy continuously to electrically heated or refrigerated apparel worn by a person equipped with a harness carrying a pick-up shoe and in contact with stationary conductors.

It should be appreciated that modifications and alterations obvious to those skilled in the art are not to be considered as beyond the scope of the present invention. For example, it may be desirable to vary the output voltage of the device for speed control for example, using the SCR's or transistors. This could be achieved by turning on the SCR or transistor partway through a cycle or for some particular cycles only. It should also be appreciated that any combination of alternating current or direct current input and alternating current or direct current output is envisaged.

Claims

Cl ai ms

1. An apparatus for conducting electrical energy from a stationary array of conductors to an object which may move relative to said conductors, comprising: pick-up means comprising a plurality of contact segments, each adapted to contact one of said conductors at a given time, a pair of terminals at each contact segment, current output means, and circuit means interposed between said terminals and said current output means to provide a selected form of electrical energy at said current output means.

2. An apparatus for conducting electrical energy from stationary conductors to an object which may move relative to said conductors, comprising: a pick-up shoe comprising a plurality of contact segment assemblies, each contact segment assembly comprising a main contact segment and an auxiliary contact segment electrically insulated from the main contact segment, each contact segment assembly being adapted to contact one of said stationary conductors at a given time, current output means, control means interposed between said auxiliary contact segment and said current output means, and circuit means interposed between said main contact segment and said current output means being controlled by said control means to provide a selected form of electrical energy at said current output means.

3. The apparatus of claim 1 wherein each contact segment comprises a single plate of electrically conductive material.

4. The apparatus of any one of the preceding claims wherein said circuit means comprises rectification or conversion means.

5. The apparatus of claim 2 wherein said control means comprises rectification control means and/or conversion control means.

6. In combination with the apparatus of any one of the preceding claims, at least two spaced parallel conductors suspended above a roadway or factory floor for example.

7 : The combination of claim 6 wherein adjacent conductors are of alternate polarity.

8. The combination of claim 6 or claim 7 wherein said parallel conductors are suspended by a support network comprising a plurality of support bridges extending across the parallel conductors and configured to step over alternate conductors whilst being connected to other alternate conductors.

9. An apparatus for conducting electrical energy from an array of conductors, each of said conductors being energised at a different potential from adjacent conductors, the apparatus comprising: pick-up means comprising: an array of contact segments, each contact segment being adapted to contact one, and only one, of the energized conductors at a given time, each contact segment comprising one or more terminals, the quantity of segments and the location of each of said contact segments in the array of contact segments being such that, at any given time, and for each different conductor potential, there shall be at least one contact segment conducting from the conductor, a current output means, and a circuit means interposed between said contact segment terminals and said current output means to provide a selected form of electrical energy at the current output means for a given form of electrical current input.

10. An apparatus substantially as hereinbefore described with reference to the accompanying drawings.

11. A system comprising in combination, the apparatus of claim 8 and a plurality of uniformly spaced parallel conductors.