GB2431294A

GB2431294A - Generator

Info

Publication number: GB2431294A
Application number: GB0520725A
Authority: GB
Inventors: Trevor David Smith
Original assignee: SUXE INTERNAT Ltd
Current assignee: SUXE INTERNAT Ltd
Priority date: 2005-10-12
Filing date: 2005-10-12
Publication date: 2007-04-18
Anticipated expiration: 2025-10-12
Also published as: GB2431294B; GB0520725D0

Abstract

A generator has a stator part 11 and rotor part 12 and a controller. The stator part comprises a plurality of stator nodes 13, each node comprising a core 18 extending generally radially, the core being surrounded by a coil 19 and the rotor part comprising a plurality of rotor nodes 22 mounted on a support part 20, the support part being mounted for rotation relative to the stator part. The rotor part further comprising a conductor 25, which may be tubular or formed of copper rods (85 fig 4), disposed between the rotor node(s) and the stator part. An angular position detector detects the position of the rotor relative to the stator, the controller calculating the position of the rotor and controlling the supply of electrical current to one or more stator nodes to as a rotor node passes the stator nodes. The rotor core may carry coils 24 which are supplied via a contactless rotary transformer arrangement 30 comprising stator cores and coils 32,33 connected to the controller and rotor cores and coils 36,37 connected to coils 24. A similar arrangement 40 removes the generated power from the conductor 25. Three phase current may be obtained by using 3 generators or alternatively three arrangements 40 relating to separate equiangular sections of the rotor. The specification also indicates that the generator can be operated as a motor.

Description

Title: Generator

Description of Invention

This invention relates to an electrical generator.

In general, electrical generators operate by rotating a conducting rotor through a magnetic field. This induces an electric current in the conductor.

It is known to refine such generators by providing multiple poles, windings and so forth to provide an electrical current with greater efficiency and with frequency or voltage characteristics as desired. However, a common feature to all generators is that the electrical power generated will inevitably be less than the mechanical power supplied to rotate the rotor due to losses in magnetic and mechanical systems.

An aim of the invention is to reduce or overcome the above problem.

According to a first aspect of the invention, we provide a generator comprising a stator part and rotor part and a controller, the stator part comprising a plurality of stator nodes, each node comprising a core extending generally radially, the core being surrounded by a coil, the rotor part comprising a plurality of rotor nodes mounted on a support part, the support part being mounted for rotation relative to the stator part, the rotor part further comprising a conductor disposed between the rotor node and the stator part, an angular position detector being provided to detect the position of the rotor relative to the stator, and wherein the controller is operable to receive a signal from the angular position detector to calculate the position of the rotor and to control the supply of electrical current to one or more stator nodes as a rotor node passes the stator nodes.

The controller may be operable to supply an electrical current to a coil of a stator node to magnetise the node when a rotor node is opposite the node, and to de-magnetise the stator node as the rotor node passes the stator node.

The controller may be operable to control a supply of electrical current to a stator node such that the stator node is magnetised with a first polarity when the rotor node is opposite the stator node, and to supply currents to the stator node such that it is magnetised with an opposite polarity as the rotor node passes the stator node.

Each stator node may comprise a plurality of cores, each core having a coil surrounding each core.

The rotor node may comprise a radially extending core and a coil surrounding the core.

The rotor node coils may be connected to the conductor to generate a magnetic field with the opposite polarity to the stator nodes when the rotor part is rotated relative to the stator part.

The rotor node coils may alternatively be connected to a rotor node coil supply connection to supply an electrical current to the rotor node to generate a magnetic field with the opposite polarity to the stator nodes.

An end cap may be disposed at each end of the stator part and extend between the stator part and the rotor part.

The end caps may comprise discs mounted fixed relative to the stator part and having an aperture in to which an end part of the rotor part extends.

The stator part may comprise a shell to support the stator nodes.

The stator shell may comprise a material having a relatively high permeability.

The stator shell may alternatively comprise a plurality of longitudinally extending bars of high permeability material.

The conductor may comprise a solid element.

Alternatively, the conductor may comprise a plurality of separately extending elements.

Each of the stator nodes may further comprise an end cap of a high permeability material.

Each of the rotor nodes may comprise an end cap of high resistivity material.

Each rotor node may comprise a plurality of cores.

According to a second aspect of the invention, we provide a generator system comprising a generator according to the first aspect of the invention and a driving element operable to rotate the rotor part relative to the stator part.

The generator system may comprise three generators and a output control to provide a three-phase supply.

The present invention will now be described by way of example only with reference to the accompanying drawings wherein: Figure 1 is a longitudinal sectional view through a generator embodying the present invention, Figure 2 is a section on line 2-2 of Figure 1, Figure 3 is a section on line 3-3 of Figure 1, Figure 4 is a view similar to Figure 2 but through an alternative embodiment of the generator of Figure 1, Figure 5 is a diagrammatic illustration of a controller for the generator of Figure 1, Figure 6 is a diagrammatic illustration of the magnetic field lines in the generator of Figure 1, and Figures 7a and 7 are an illustration of the operation of the rotor nodes of the generator of Figure 1, and Figure 8 is a diagrammatic illustration of a generating system for generating a three-phase electrical output.

Referring now to Figure 1 a generator embodying the present invention is generally shown at 10, comprising a stator part 11 and a rotor part 12. The stator part 11 comprises a plurality of nodes 13, successive nodes being separated by an insulator 14 of appropriate type. The nodes 13 are supported on a stator shell 15 of longitudinally extending shell bars 1 5a which preferably comprise a material having a high permeability. At the other end of the stator nodes 13 is a stator end bar 16, again made of some appropriate high (Q-fvt') permeability material such as Nilomagfr7 Alloy. The stator part 11 is fixed relative to an outer casing 17 of the generator 10.

As in Figure 2, each stator node 13 comprises a core 18 with a coil 19 surrounding the core. A longitudinal extending row of cores 18 are held in a common stator shell bar, comprising for example Nilomag(77 Alloy. In the example of Figures 1 and 2, the cores 18 extend radially of the generator 10 and are disposed at equi-angular distances around the circumference of the stator shell and equidistantly longitudinally of the generator 10.

The rotor part 12 comprises a support part generally shown at 20. The support part 20 has a central part 21 to support a plurality of rotor nodes 22 which preferably comprises a monolithic cast body with high permeability, and two end parts 41, comprising an appropriate low permeability material, which act as axles journalled in bearings 42 fixed relative to the outer case 17 of the generator 10 to allow the rotor part 12 to rotate relative to the stator part 11.

As shown in Figures 1 and 2, each rotor node 22 comprises a rotor core 23 which extends radially outwardly of and is supported on the support part 20.

Each radially extending core has a surrounding coil 24. Disposed between the rotor nodes 22 and the stator part 12 is a conductor 25, in this example comprising a solid copper tube. The conductor 25 is supported by end brackets 26 which are fixedly mounted by bolts 27 on the support part 20 such that the conductor 25 rotates with the support part 20. A rotable end part end cap 28 extends around the rotor nodes 22, comprising an appropriate high resistivity material such as a plastics material. The air gap between the conductor 25 and the stator end bar 16 is as small as is feasible, in the present example 0.3mm, to optimise the permeability of the magnetic circuit and reduce magnetic fringing.

To supply power to the rotor coils 24, a power input magnetic interface (PIMI) is shown at 30. To extract power from the conductor 25, a power output magnetic interface (POMI) is generally shown at 40. The PIMI 30 and the POMI 40 have the same general structure except that the PIMI is electrically connected to the coils 23, whereas the POMI is electronically connected to the conductor 25. Referring now to Figure 3, the PIMI 30 is generally illustrated.

The PIMI 30 comprises an outer ring 31 having a plurality of outer ring cores 32 attached thereto and extending radially inwardly therefrom. Each of the outer ring cores 32 has a coil 33 surrounding it, and a cap 34. The outer shell 31 is fixed relative to the outer case 17. The PIMI 30 further comprises an inner part 35 which supports inner part cores 36 which extend radially outwardly therefrom. Each inner part core 36 has a corresponding coil 37 surrounding the core, and an appropriate cap 38. The inner part 35 is mounted on the axle 41 of the support part 20 for rotation therewith. The caps 34, 38 are shaped such that the caps 34 have a concave surface and the caps 38 have a complementary convex surface such that the end caps 34, 38 are able to pass over one another when the inner part 35 is rotated relative to the outer part 31, with an air gap of about 0.3mm.

The effect of the PlMl/POMI structure shown in Figure 3 is that when electrical current is supplied to one set of coils 33, 37, an electrical current will be induced in the other set of coils 33, 37 and thus the PlMl 30 or POMI 40 will act as an interface to permit electrical power to be supplied to or removed from the generator 10. Thus, for the PIMI 30 the coils 37 are connected to the rotor coils 24 and the outer coils 33 are connected to a form of electrical power to cause the appropriate energisation of the rotor nodes 22, whilst the inner coils 37 of the POMI 40 are connected to the conductor 35 and the coils 33 of the outer part 31 are connected to a power output to supply the electrical current from a generator to an appropriate load. This is advantageous in that there is no resistance due to the physical interaction of components such as a commutator or carbon brushes. Eddy currents being induced within the system are minimised and operating temperatures are relatively low.

Advantageously, the PIMI and POMI structures are magnetically closed, unlike other generally known energy transfer systems.

At one end of the rotor part 12, an angular position detector is provided to detect the rotational position of the rotor part 12. This may comprise a rotary encoder of known type.

To provide for low torque operation of the generator, the stator nodes 13 are each operable by a controller generally shown at 60 in Figure 5. The control nodes in this example comprise three cores 18 and three coils 19, but may comprise any other number of cores as desired. In general, the nodes 13 are connected to a control output board 61 such that each node 13 is controllable independently, that is the polarity, voltage and the power of electrical current supplied to that node can be controlled independently of the status of the other nodes 13. All cores 18 and coils 19 of the node are controlled as a group, but it might be envisaged that independent coils 19 could be energised or de-energised separately if appropriate controls are provided. As shown in Figure 5, the controller 60 is operable to receive instructions from and supply information to an operator interface generally shown at 62, and is operable to receive status from the data encoder 50. Other sensors, such as a temperature sensor 63 may be connected to the controller 60. The controller 60 controls the electrical current supplied to the stator and rotor coils through the coil output board 61 in accordance with information received from the rotary encoder 50 as will be described in more detail below.

The stator part 11 is further provided with end plates shown at 70 which are fixedly attached relative to the stator shell 15. In this example the end plates are generally circular, and have an aperture 71 at the centres thereof through which the axles 41 of the rotor support part 20 are passed. The end plates 70 comprise a high permeability material, and provide a return path for the magnetic field lines. As illustrated in Figure 6, the field lines extend generally radially through the stator 11 and rotor part 12, and then extend axially from the rotor part 12 to the end cap where they are directed radially through the end plates 70 and then longitudinally through the stator shell 15 to close the circuit. This is advantageous in that the field lines will extend perpendicularly to the conductor as the rotor part 12 rotates, and also cause a lower rotational torque on the rotor axle 41. The reduction or elimination of air gaps in the magnetic field line path reduces the reluctance of the system, reduces magnetic fringing and reduces the excitation power needed to span the air gap.

The operation of the generator will now be described with reference to Figure 7a and Figure 7b. In operation, a torque is applied to the rotor part 12, for example from an internal combustion engine or other source of power such that the rotor part 12 is rotated relative to the stator part 11. Where a PIMI is provided to energise the rotor nodes 22, an appropriate electrical current is supplied through the PIMI 30. The controller 60 will control the supplied electrical current to the stator nodes 13 through the output board 61 such that the opposed ends of the stator nodes 13 and rotor node 22 have the opposite polarity.

Using the angular position information from the rotary encoder 50, the controller 60 is operable to energise and de-energise the stator nodes 13 as the rotor node 22 passes each stator node 13. In particular, the controller 60 is operable to energise a stator node 13 when the rotor node 22 is opposite or approaching that rotor node 13, as illustrated by movement of the rotor node 22 in the direction A of Figures 7a and 7b. To reduce opposing torque on the rotor part 12 however, the controller 60 is operable to de-energise the node 13 opposite the trailing edge of the rotor node 22 as illustrated in Figure 7b. This will reduce the force acting on the rotor node 22 in the opposite direction to direction A by virtue of the reduced magnetic attractive forces between the rotor node 22 and the stator node 13. It may be considered that, instead of simply de-energising the stator node 13, the polarity may be reversed such that the stator node 13 located at the trailing edge of the rotor node 22 actually provides a repulsive force acting to urge the rotor node 22 in the direction of rotation A. Further energising the group of three cores and the adjacent nodes ensures that the field lines will extend radially and hence perpendicular to the conductor.

The generator 10 produces a single phase, but as shown in Figure 8, a group of three such generators 10 may be operated to provide a threephase electrical output. In Figure 8, three generators 10 are shown, each driven by an appropriate motor 80. The output from each generator 10 can be combined at an appropriate control panel 81 to provide a three phase electrical output 82.

Alternatively a single generator 10 may be provided with three or more POMIs each relating to separate equi-angular sections of the rotor part 12 and generating electrical outputs having the required phase difference.

The conductor 25 need not necessarily comprise a solid conductor as discussed herein, but as shown in Figure 4 may comprise a plurality of individual elements 85, for example longitudinally extending copper rods or bars or other such discrete element as may be desired.

Advantageously, the generator 10 can provide an output current at a desired frequency, that is irrespective of the rotational speed of the rotor part 12. If the rotational speed of the rotor part 12 varies, the controller 60 adjusts the sequence of energising the stator nodes 13 to maintain the required frequency.

The generator 10 may be operated as a motor by reversing the operation processes described above. In this second mode of operation, the rotor nodes 22 are energised via the PIMI 30 or otherwise. The controller 60 will control the supplied electrical current to the stator nodes 13 through the output board 61 such that the opposed ends of the stator nodes 13 and rotor nodes 22 have the same polarity.

The repulsion force acting between the rotor nodes 22 and the stator nodes 13 will cause the rotor part 12 to rotate relative to the stator part 11. Using the angular position information from the rotary encoder 50, the controller 60 is operable to control the polarity of the stator nodes 13 such that the repulsive force will produce a substantially constant turning motion of the rotor part 12.

The controller 60 can be operated to energise and de-energise the stator nodes 13 and rotor nodes 22 such that the electrical output can exhibit any required waveform, such as sinusoidal, square, or D.C.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A generator having a stator part and rotor part and a controller, the stator part comprising a plurality of stator nodes, each node comprising a core extending generally radially, the core being surrounded by a coil, the rotor part comprising a plurality of rotor nodes mounted on a support part, the support part being mounted for rotation relative to the stator part, the rotor part further comprising a conductor disposed between the rotor node and the stator part, an angular position detector being provided to detect the position of the rotor relative to the stator, and wherein the controller is operable to receive a signal from the angular position detector to calculate the position of the rotor and to control the supply of electrical current to one or more stator nodes as a rotor node passes the stator nodes.

2. A generator according to claim 1 where the controller is operable to supply an electrical current to a coil of a stator node to magnetise the node when a rotor node is opposite the node, and to de-magnetise the stator node as rotor node passes the stator node.

3. A generator according to claim 1 wherein the controller is operable to control a supply of electrical current to a stator node such that the stator node is magnetised with a first polarity when the rotor node is opposite the stator node, and to supply electrical current to the stator node such that it is magnetised with an opposite polarity as the rotor node passes the stator node.

4. A generator according to any one of claims 1 to 3 wherein each stator node comprises a plurality of cores, each core having a coil surrounding the core.

5. A generator according to any one of the preceding claims wherein each rotor node comprises a radially extending core and a coil surrounding the core.

6. A generator according to claim 5 wherein the rotor node coils are electrically connected to the conductor to generate a magnetic field with the opposite polarity to the stator nodes when the rotor part is rotated relative to the stator part.

7. A generator according to claim 6 wherein the rotor node coils are connected to a rotor node coil supply connection to supply an electrical current to the rotor node to generate a magnetic field with the opposite polarity to the stator nodes.

8. A generator according to any one of the preceding claims further comprising an end cap disposed at each end of the stator part and extending between the stator part and the rotor part.

9. A generator according to claim 8 wherein the end caps comprise discs mounted fixed relative to the stator part and having an aperture through which an end part of the rotor part extends.

10. A generator according to any one of the preceding claims wherein the stator part comprises a shell to support the stator nodes.

11. A generator according to claim 10 wherein the stator shell comprises a material having a relatively high permeability.

12. A generator according to claim 11 wherein the stator shell comprises a plurality of longitudinally extending bars of high permeability material.

13. A generator according to any one of the preceding claims wherein the conductor comprises a solid element.

14. A generator according to any one of claims 1 to 12 wherein the conductor comprises a plurality of separately extending elements.

15. A generator according to any one of the preceding claims wherein each of the stator nodes further comprises an end cap of a high permeability material.

16. A generator according to any one of the preceding claims wherein each of the rotor nodes comprises an end cap of high resistivity material.

17. A generator according to any one of the preceding claims wherein each rotor node comprises a plurality of cores.

18. A generator substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

19. A generator system comprising a generator according to any one of claims 1 to 18 and a driving element operable to rotate the rotor part relative to the stator part.

20. A generator system according to claim 19 comprising three generators and a output control to provide three-phase supply.

21. A generating system substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

22. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.