WO2020154760A1

WO2020154760A1 - System and method for reducing power consumption in a power supply circuit

Info

Publication number: WO2020154760A1
Application number: PCT/AU2020/050032
Authority: WO
Inventors: Laurence Gonano
Original assignee: Beovista Trading Pty Ltd
Priority date: 2019-01-31
Filing date: 2020-01-22
Publication date: 2020-08-06

Abstract

A system for reducing power consumption in a power supply circuit enables reducing the voltage supplied to a load and thus the electrical energy consumed by the load. The system includes a magnetic core defining and at least partially surrounding a passage; a primary conductor connected between an electrical supply and a load, wherein the primary conductor passes through the passage; a switch having a first state and a second state; and a controller connected to: the primary conductor for measuring a load voltage at the load, and the switch, wherein the controller switches the switch between the first state and the second state based on the load voltage to effect a voltage change along the primary conductor as it passes through the passage defined by the magnetic core.

Description

TITLE

SYSTEM AND METHOD FOR REDUCING POWER CONSUMPTION IN A

POWER SUPPLY CIRCUIT

FIELD OF THE INVENTION

[0001 ] This invention relates generally to a system and method for reducing power consumption in a power supply circuit, and in particular for substantially adjusting a supply voltage, and consequently supply power, relative to an internal load and an external voltage.

BACKGROUND TO THE INVENTION

[0002] Reference to background art herein is not to be construed as an admission that such art constitutes common general knowledge in Australia or elsewhere.

[0003] Alternating current (AC) power supply systems used to generate, distribute and deliver energy to commercial, industrial, and residential properties are only semi-regulated in that voltage supplied to electrical loads can vary up and down. As an example, in an electrical supply system with a nominal phase to neutral voltage of 230VAC, the actual voltage delivered to the electrical load can vary between 216VAC and 253VAC, and the phase to neutral voltage can also be unbalanced between the three electrical supply phases. This variation is typically considered acceptable; however, the efficiency, life expectancy and power consumption of electrical loads will change depending on the supply voltage and phase voltage balance. [0004] Many products have been developed offering the capability to regulate voltage to commercial electrical loads with a view to reducing overall power consumption. However, designs used to date are typically constructed from tapped power transformers with the addition of switching and control elements. These tapped transformer implementations tend to be large, heavy, and expensive to manufacture, which restricts their usefulness.

[0005] Typical transformer construction will have a primary winding and a secondary winding, and these windings are wrapped around a magnetic core in many turns or layers, thus increasing the transformer size and further restricting the shape options for the final product, and inhibiting cooling.

[0006] In another approach, a variable transformer (also known as a VARIAC) may be used to regulate the voltage supplied to a load. Variable transformers or combinations of variable transformers and fixed transformers have been used to smoothly vary or regulate the voltage supplied to a load. However, this approach is difficult to scale up to the very large currents typically found in commercial applications, and this solution usually requires significant floor area in locations where this is scarce and commercially valuable. Thus, the use of VARIACs can present a large and expensive solution.

[0007] There is therefore a need for an improved system and method for reducing power consumption in a power supply circuit.

OBJECT OF THE INVENTION

[0008] It is an object, of some embodiments of the present invention, to provide consumers with improvements and advantages over the above described prior art, and/or overcome and alleviate one or more of the above described disadvantages of the prior art, and/or provide a useful commercial choice.

SUMMARY OF THE INVENTION

[0009] In one form, although not necessarily the only or broadest form, the invention resides in a system for reducing power consumption in a power supply circuit comprising: a magnetic core defining and at least partially surrounding a passage; a primary conductor connected between an electrical supply and a load, wherein the primary conductor passes through the passage; a switch having a first state and a second state; and a controller connected to: the primary conductor for measuring a load voltage at the load; and the switch, wherein the controller switches the switch between the first state and the second state based on the load voltage to effect a voltage change along the primary conductor as it passes through the passage defined by the magnetic core.

[0010] Preferably the switch has a first pole, a second pole, and a common pole.

[0011 ] Preferably the magnetic core comprises a winding. Preferably the winding comprises a wire. Preferably the winding comprises a first end and a second end wound onto the magnetic core. [0012] Preferably the primary conductor comprises a first end and a second end. More preferably the first end is connected to the electrical supply. Even more preferably the second end is connected to the load.

[0013] Preferably the first end of the winding is connected to the first end of the primary conductor, and to the first pole of the switch. More preferably the second end of the winding is connected to the common pole of the switch.

[0014] Preferably the winding is formed such that the passage of the winding, in a direction from the first end to the second end of the winding, passes firstly through the centre of the magnetic core in the same direction as that of the primary conductor as the primary conductor passes through the centre of the magnetic core in a direction from the first end to the second end.

[0015] The system preferably comprises a supply neutral conductor. Preferably the second pole of the switch is connected to the supply neutral conductor.

[0016] Preferably the switch comprises thyristor pairs.

[0017] Preferably the controller comprises a voltage measurement unit for measuring the load voltage.

[0018] Preferably the controller comprises a comparator for comparing the load voltage to a voltage set point.

[0019] Preferably the controller comprises a cell switch driver unit for switching the switch between the first state and the second state.

[0020] Preferably, in the first state, the switch connects the common pole to the first pole allowing current of the electrical supply to pass through the primary conductor without any voltage change. [0021 ] Preferably, in the second state, the switch connects the common pole to the second pole whereby the voltage of the electrical supply is dropped to the voltage set point.

[0022] The system preferably comprises a plurality of magnetic cores. The system preferably comprises a plurality of switches.

[0023] Preferably the primary conductor has a continuous cross section.

[0024] Preferably the magnetic core comprises a single magnetic path.

[0025] Preferably the magnetic core forms a magnetic loop.

[0026] Preferably the primary conductor passes through the magnetic loop.

[0027] Preferably the winding wire has a uniform cross section.

[0028] Preferably a cross section of the winding is smaller than a cross section of the primary conductor.

[0029] Preferably the magnetic core is a toroidal core. Alternatively the magnetic core is a C core. Further alternatively the magnetic core is an R core.

[0030] Preferably the magnetic core comprises laminated electrical steel.

[0031 ] Preferably, the primary conductor includes no electrical taps.

[0032] Preferably, the winding includes no electrical taps.

[0033] In another form, the invention resides in a method for reducing power consumption in a power supply circuit comprising: connecting a magnetic core to a primary conductor; connecting the primary conductor to an electrical supply and a load; connecting a controller to the primary conductor to measure a load voltage; controlling the voltage on the primary conductor, such that the voltage on the primary conductor is maintained at a set point.

[0034] Further features and advantages of the present invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] By way of example only, preferred embodiments of the invention will be described more fully hereinafter with reference to the accompanying figures, wherein:

[0036] FIG. 1 is a block diagram illustrating a system for reducing power consumption in a power supply circuit according to an embodiment of the present invention;

[0037] FIG. 2 is an electrical schematic of a voltage control cell and block diagram of a control system according to an embodiment of the present invention;

[0038] FIG. 3 is an electrical schematic of a system for reducing power consumption in a power supply circuit according to an second embodiment of the present invention;

[0039] FIG. 4 is a block diagram of a three phase voltage regulator implementation according to a further embodiment of the present invention;

[0040] FIG. 5 is an electrical schematic illustrating a further embodiment of a system for reducing power consumption in a power supply circuit according to the present invention; [0041 ] FIG. 6 is an electrical schematic illustrating a further embodiment of the present invention whereby multiple voltage control cells of differing voltage control capacity are used;

[0042] FIG. 7 is an electrical schematic illustrating a further embodiment whereby an additional pole is added to the switch of the voltage control cell;

[0043] FIG. 8 illustrates an embodiment of a magnetic core in accordance with the present invention;

[0044] FIG. 9 illustrates a further embodiment of the present invention whereby the control system feedback voltage can be derived from a remote point in the electrical distribution system;

[0045] FIG. 10 illustrates a further embodiment of the present invention whereby the excitation source for the winding on the voltage control cell can alternatively be derived from the second end of the primary conductor.

DETAILED DESCRIPTION OF THE DRAWINGS

[0046] FIG. 1 is a block diagram showing a system 100 for reducing power consumption in a power supply circuit according to some embodiments of the present invention. The voltage regulation system 100 includes an AC power supply 110, a voltage control cell 120, a control system 130 and a load 140. An input of the voltage control cell 120 is connected to the AC power supply 110 which, for example, can be a 230VAC 50Hz power supply. On an output side, the voltage control cell 120 is connected to the control system 130 and the load 140. The control system 130 monitors the output voltage supplied to the load 140 and controls the state of the voltage control cell 120 in order to adjust the output voltage supplied to the load within an upper and lower limit. As an example, for a 230VAC power supply, the lower limit can be 219V and the upper limit can be 230VAC.

[0047] Advantageously, reducing the voltage supplied to the load 140 reduces the electrical energy consumed by the load 140.

[0048] FIG. 2 is a system 200 for reducing power consumption in a power supply circuit according to some embodiments of the present invention. Similar to the system 100 of FIG. 1 , the system 200 includes a power supply 210, a voltage control cell 220, a control system 230 and a load 240. As shown in this particular embodiment, the voltage control cell 220 is constructed such that there is a primary conductor 250 which is of uniform cross sectional area.

[0049] In some preferred embodiments of the present invention, the primary conductor 250 may be a single straight conductor, such as an electrical power bus bar. The primary conductor 250 has a first end 251 connected to the power supply 210 and a second end 252 connected to the load 240.

[0050] In the instance of a single phase implementation, such as the embodiment illustrated in FIG. 2, the first end 251 of the primary conductor 250 is connected to an active terminal 211 of the AC power supply system 210. The second end 252 is connected to an active terminal 241 of the load 240.

[0051 ] There is also a second electrical connection defining a common neutral connection 253 between the power supply 210 and the load 240. The common neutral connection 253 connects a neutral terminal 212 of the AC power supply 210 and to a neutral terminal 242 of the load 240. [0052] The voltage control cell 220 includes a magnetic core 221 . The magnetic core 221 can be made from a suitable laminated electrical steel typically used in the manufacture of transformers, motors and other AC electromagnetic devices. The required magnetic and electrical properties of the steel used to make the magnetic core 221 will be apparent to one skilled in the art and should be selected to minimise electrical and magnetic losses at the operating frequency of the power supply 210.

[0053] The magnetic core 221 has a single magnetic path, such as a toroidal core, Ό’ core, ‘R’ core or other core shape that has a single, continuous magnetic path, and uniform cross section of magnetic material along the magnetic path.

[0054] In some preferred embodiments, the magnetic core 221 has a rectangular cross section however other cross sections, for example a circular or square cross-section, with or without rounded corners would be suitable.

[0055] The cross sectional area of the magnetic core 221 is a function of the required voltage change on the primary conductor 250 as it passes from the first end 251 , through the magnetic core 221 , to the second end 252, and of the operating frequency of the power supply 210, and the desired maximum magnetic flux density in the magnetic core 221. The following formula describes this relationship

[0056] Where Core Area is in mm² , and V is an AC voltage representing the voltage changing capacity of the voltage control cell 220, and / is a frequency of the power supply 210 in Hz, and B is the maximum desired magnetic flux density in Tesla in the magnetic core 221. As an example, if the voltage control cell 220 is required to have an ability to change the voltage by 5 volts AC RMS maximum at 50Hz and maximum flux density of 1.5 Tesla, then the required cross sectional area of the magnetic core 221 shall be determined by:

5 x 2

Core Area = 1,000,000 x - - - -—

(2 x 7G x 50 x 1.5)

Core Area = 15,005.27 mm²

[0057] The voltage control cell 220 also comprises a winding 222 which has a first end 223 and a second end 224. The winding 222 can be made from enamelled winding wire such as solid copper or aluminium with a coating of insulating enamel of suitable temperature rating. However, those of ordinary skill in the art will recognise that the winding 222 can also comprise multiple strands of a smaller conductor in parallel to form the desired equivalent cross sectional area, or any other form that achieves the required number of electrical turn around the magnetic core. This may be done for the purpose of improving conductor flexibility, reducing losses, improving short circuit withstand strength, improving heat transfer, or other manufacturing and performance advantages.

[0058] In some preferred embodiments, the winding 222 should be of a uniform cross sectional area between the first end 223 and the second end

224. [0059] In some further preferred embodiments, the winding 222 can be wound onto a bobbin (not shown) or similar winding container or forming technique and then fitted to the magnetic core 221.

[0060] In some alternative embodiments, the winding 222 can be wound directly onto the magnetic core 221 with suitable mechanical protection and electrical insulation in place between the winding 222 and the magnetic core 221.

[0061 ] The required number of turns of the winding 222 can be written as a function of the maximum voltage changing capacity of the cell for the primary conductor 250 and the AC voltage of the power supply 210 as follows:

_ Vs

N winding ^~ y

_ 230

N Winding ^~ ^

[0062] Where N_winding is the number of turns required for winding 222, Vs is the nominal voltage of the power supply 210, and Vc is the maximum voltage changing capacity of the voltage control cell 220. As an example, if the voltage control cell is required to have an ability to change the voltage by 5 volts AC RMS maximum in the primary conductor 250, and the AC voltage of the power supply is 230 volts AC RMS, then:

_ 230

N Winding ^~ ^

N winding — 46 TUTTIS

[0063] The required cross sectional area of the winding 222 is a function of the current it must carry, and this current is a function of both the current flowing through the primary conductor 250 and the turns used in the winding 222 as follows:

[0064] Where l_Winding is the AC RMS current in Amperes in the winding 222, Ip is the AC RMS current in Amperes in the primary conductor 250, and N winding is the turns of the winding 222. To progress the current example, if the current in the primary conductor is 1000 Amperes AC RMS then the current in the winding 222 can be determined as:

1000

/ Winding = 21.74 Amperes

[0065] The desired cross sectional area of the winding 222 can now be determined by the following formula:

[0066] Where Area_winding is the cross sectional area of the winding 222, I winding is the AC RMS current in Amperes in the winding 222, and / is the desired current density in the winding 222 expressed in Amperes per mm². To further progress the current example above, if the desired current density on the winding 222 was 3 Amperes /mm² then the required cross sectional area of the winding 222 is determined as:

21.74

Area_winding = 7.24 mm² [0067] One of ordinary skill in the art will appreciate that a particular design may dictate that some parameters, such as current density /, will need to be varied depending on the material used to make the winding 222, the geometry of the magnetic core 221 and the winding 222, the required operating temperature etc., and that some of these design parameters may need to be optimised through empirical testing techniques.

[0068] The voltage control cell 220 also includes a switch 260 with a common pole 261 connected to the second end 224 of the winding 222. The switch 260 also has a first pole 262 connected to the first end 223 of the winding 222 and also to the first end 251 of the primary conductor 250.

[0069] Additionally, the switch 260 includes a second pole 263 connected to the common neutral connection 253 which in turn connects to the neutral terminal 212 of power supply 210 and to neutral terminal 242 of the load 240.

[0070] In the illustrated embodiment, the voltage control cell 220 can be operated in either one of two possible states which are described below.

[0071 ] In a first state the switch 260 will make a connection between the common pole 261 and the first pole 262 leaving no connection between the common pole 261 and the second pole 263. In this state the magnetic flux in the magnetic core 221 is forced effectively to zero eliminating any induced voltage from winding 222 through the magnetic core 221 and into the primary conductor 250.

[0072] In this first state the voltage change on the primary conductor 250 is zero and current passes from the first end 251 , through the magnetic core 221 , to the second end 252 and the load 240, which receives the full and unchanged voltage from the supply 210. [0073] In a second state the switch 260 will make a connection between the common pole 261 and the second pole 263 of the switch 260, leaving no connection in the switch 260 between the common pole 261 and the first pole 262.

[0074] In this second state the active terminal 211 of the power supply 210 is connected to the first end 223 of winding 222, and the neutral terminal 212 of the power supply 210 is connected to the second end 224 of winding 222.

[0075] In the above described second state, the full design magnetic flux density is developed in the magnetic core 221. Through electro-magnetic induction the primary conductor 250 develops the full voltage change on the primary conductor 250 as current passes from the first end 251 , through the magnetic core 221 , to the second end 252.

[0076] In this state, and using the examples outlined previously, a voltage change of 5 volts AC RMS is dropped along the primary conductor 250 as the primary conductor 250 passes through the passage in the magnetic core 221 , and the load 240 receives a voltage of 5 volts AC RMS below that of the voltage at the terminals 211 , 212 of the power supply 210.

[0077] A control circuit 230 employs a measurement circuit 231 to measure the voltage supplied to the load at terminals 241 , 242 and operates on the voltage signal such that it can be compared to a required set point value of a set point indicator 232.

[0078] A comparator 233 determines if the output voltage is significantly above the set point value, and if so commands a cell switch driver 234 to set the state of the cell switch 260 to the second state. In this second state, as described above, the common pole 261 is connected to the second pole 263 thereby forcing the voltage control cell to drop the voltage to the load 240 and maintain the required set point value.

[0079] If the output voltage as measured by the voltage measurement unit 231 falls significantly below the set point value then the comparator 233 will control via the cell driver 234 the state of the cell switch 260, and will return the state to the first state wherein the common pole 261 is connected to the first pole 262, thereby shorting the cell winding 222 and allowing the full voltage of the power supply 210 to pass through the primary conductor 250 to the load 240 without any voltage drop or change as it passes through the passage defined by and in the centre of the magnetic core 221.

[0080] An ordinary person skilled in the art will recognise that the simple mechanical switch 260 described in FIG. 2 could alternatively be implemented using solid state techniques such as thyristor pairs which will now be described.

[0081 ] Turning to FIG. 3, a further embodiment of a system for reducing power consumption 300 is shown. The system 300 is substantially similar to the system 200 as described in FIG. 2 and includes a power supply 310, a voltage control cell 320, a control system 330 and a load 340. The system 300 also includes a switch 360 with a common pole 361 , a first pole 362 and a second pole 363.

[0082] The first state of the of the voltage control cell 320 is achieved when a thyristor pair 364 conducts, connecting the common pole 361 with the first pole 362 and effectively shorting the winding 322 and preventing any induced voltage change on the primary conductor 350 as it passes through the passage of the magnetic core 321. [0083] Alternatively, the second state is achieved when a thyristor pair 365 conducts and while the thyristor pair 364 does not conduct, and the common pole 361 is connected to the second pole 363.

[0084] In this second state the voltage from the supply 310 is connected to the winding 322 and the full voltage changing capability is induced into the primary conductor 350 as it passes through the passage of the magnetic core 321. In this case the load 340 receives a voltage less than the supply voltage 310 by an amount equalling the cell voltage changing capacity. The control system 330 monitors the voltage at the input to the load 340, compares it to the desired voltage set point and controls the state of the switch 360 accordingly.

[0085] FIG. 4 illustrates a system 400 for reducing power consumption in a three phase configuration according to another embodiment of the present invention. Similar to the system 200, the system 400 includes a power supply 410, a control system 430 and a load 440. The present system further includes three voltage control cells 420. These voltage control cells 420 are substantially similar to the voltage control cell 220 described in FIG. 2.

[0086] In the illustrated system 400, each of the three electrical phases has a dedicated voltage control cell 420 to control the voltage being supplied to each phase of the load 440. The control system 430 monitors all three electrical phases supplying the load 440 and individually controls the state of the voltage control cells 420, such that each phase is independently regulated.

[0087] It will be apparent to an ordinary person skilled in the art that more than one voltage control cell 420 could be used along the primary conductor, effectively summing the voltage changes along the primary conductor as it passes thorough each voltage control cell, as described in detail below.

[0088] FIG. 5 shows a system 500 as another embodiment of the present invention including a power supply 510, three voltage control cells 520a, 520b, 520n, a control system 530 and a load 540. Each of the voltage control cells 520a, 520b, 520n is substantially similar to the voltage control cell 220 in FIG. 2.

[0089] A primary conductor 550 passes through the magnetic core 521 a of the first voltage control cell 520a, then subsequently through the magnetic core 521 b of the second voltage control cell 520b and so on, with each voltage control cell having the capability of either changing the voltage on the primary conductor 550 as it passes through each core, or leaving it unchanged depending on the state of the switch in each cell.

[0090] FIG 5 shows a number of identical voltage control cells 520a, 520b, 520n are employed. When the cell switches 560a, 560b, 560n are all set to state one and the windings 522a, 522b, 522n of the cells 520a, 520b, 520n are effectively shorted, the voltage on the primary conductor 550 is unchanged as it passes through the cells 520a, 520b, 520n, and the voltage supplied to the load 540 will be the same as the voltage at the supply 510.

[0091 ] Under the command of the control system 530, the state of each cell 520a, 520b, 520n can be changed progressively from all cell switches 560a, 560b, 560n in state one to all switches in state two to develop a voltage change between the supply 510 and the load 540 varying between zero volts change and, at a maximum, the sum of the voltage changes across all the cells in series. [0092] As an example, if there are 10 cells and each cell has a maximum voltage changing capacity of 1 Volt then the voltage can be changed between the supply 510 and the load 540 between zero volts and 10 volts in a minimum voltage step of 1 volt.

[0093] FIG. 6 shows a system 600, which is another alternative embodiment of the present invention, including a power supply 610, three voltage control cells 620a, 620b, 620n, a control system 630 and a load 640. Each voltage control cell 620a, 620b, 620n further includes a respective switch 660a, 660b, 660n which are substantially similar to switches 260 and 560 described herein.

[0094] In the illustrated embodiment, the voltage changing capacity of each cell 620a, 620b, 620n is different. This varying voltage changing capacity is achieved by varying the characteristics of the magnetic cores 621 a, 621 b, 621 n. For example, voltage changing cell 620a may have a voltage changing capacity of 1 volt, while voltage changing cell 620b may have a voltage changing capacity of 2 volts and so on.

[0095] In this way the number of cells need not have a linear relationship to the total voltage dropping capability of the overall system. This enables the cell with the lowest voltage dropping capacity to determine the minimum adjustment increment, while allowing cells with larger voltage changing capacity to be used to extend the total voltage changing range of the regulating system. In the case of the system 600 described here, the control system 630 regulates the voltage supplied to the load 640 by controlling the switch states in combinations of different voltage changing characteristics in order to achieve the desired voltage to be supplied to the load 640. The truth table below demonstrates this:

[0096] In a further embodiment of the present invention, FIG. 7 shows a system 700 substantially as described above including a power supply 710, a voltage control cell 720, a control system 730 and a load 740.

[0097] In this illustrated embodiment, the winding 722 of the voltage control cell 720 connects to a switch which has two independently controlled contact arrangements 760, 770.

[0098] The first end 723 of the winding 722 is connected to a common pole 761 which connects to either the first pole 762, or alternatively to the second pole 763 under the command of the control system 730 via the control line 731. Additionally, there is a second common pole 771 connected to the second end 724 of the winding 721 , which under the command of the control system 730 via the control line 732 can connect to either the third pole 772, or to the fourth pole 773. The operation of the contact arrangements 760, 770 can be configured to achieve three possible states as follows:

[0099] In another embodiment of the present invention, FIG. 8 shows a construction for a voltage control cell 820 wherein a magnetic core 821 can be mechanically split. In the split state a substantial and significant air gap 822 is introduced into the magnetic path of the core 821. This serves to substantially reduce the coupling between a primary conductor 850 and a winding 823.

[00100] Advantageously, this allows for the system to bypass the effect of the voltage control cell 820 such that the primary conductor 850 has a negligible effect on the magnetic induction in the magnetic core 821 and thereby renders the voltage control cell 820 inoperative.

[00101 ] Further advantageously, this provides electrical protection in the case where there may be a fault in the winding 823 of the voltage control cell 820. This effectively limits the energy that can be made available to the fault and isolates the cell in a safe state that does not rely on the winding 821 or and associated circuit that is connected to it.

[00102] Often in large commercial facilities the internal electrical distribution system may be relatively long with electrical loads located far from the incoming supply. The degree to which the power supply can be reduced and regulated is limited by the voltage drop in the internal distribution network, and this voltage drop is often highest at the most distant locations from the power supply.

[00103] In a further embodiment of the present invention FIG. 9 shows a system 900. The system 900, similar to previously described embodiments, includes a power supply 910, a voltage control cell 920, a control system 930 and a load 940.

[00104] The system 900 further comprises monitoring equipment 970 at a location 980 which may be remotely located from the regulating system and power supply 910. In use, the control system 930 of the system 900 acts on a voltage measurement value taken by a voltage measurement unit 971 , which measurement value is transmitted by a transmitter 972 allowing the voltage drop of the distribution network to be automatically compensated for.

[00105] The voltage information is subsequently received at the receiver 931 in the local control system 930, decoded to a voltage signal 932, which is then compared to the set point value stored in set point value unit 933 by a comparator 934, and subsequently used by a cell switch driver 935 to control the state of a switch 960 in the voltage control cell 920.

[00106] One of ordinary skill in the art will recognise that many communications mediums can be used to transfer this information including wirelessly, or over wires and using any one of many established data communication protocols deemed suitable for the task and distance required.

[00107] In a further embodiment of the present invention, FIG. 10 shows a system 1000 including a power supply 1010, a voltage control cell 1020, a control system 1030 and a load 1040.

[00108] The voltage supply for a winding 1022 in the voltage control cell 1020 is derived from the output side of the voltage control cell 1020. When a switch 1060 is in the first state such that a common pole 1061 is connected to a first pole 1062, the winding 1022 is effectively shorted holding the magnetic flux density in the magnetic core 1021 to zero and preventing an induced voltage change in the primary conductor 1050.

[00109] In this state there is effectively no change in voltage in the primary conductor 1050 as it passes through the magnetic core 1021 to the load 1040.

[00110] When the switch 1060 is in the second state the common pole 1061 is connected to the second pole 1063 thereby connecting the first end 1023 of the winding 1022 to the second end 1052 of the primary conductor 1050, and the second end 1024 of winding 1022 is connected to the common neutral connection 1053 of AC power supply 1010.

[00111 ] In this second state the output voltage of the voltage control cell 1020 is used as the excitation source for the winding 1022, inducing a magnetic flux density in the magnetic core 1021 , which in-turn induces a voltage change in the primary conductor 1050 as it passes through the magnetic core 1021. The action of the control system 1030 remains unchanged in that it varies the state of the switch 1060 in order to influence the voltage delivered to the load 1040.

[00112] In addition, a capacitor (not shown) can also be connected across the supply 1010 or the load 1040 in order to improve the load power factor that is presented to the supply 1010. Physically the capacitors can be either separate from the voltage control cell 1020 or combined into the construction of the voltage control cell 1020.

[00113] Advantageously, according to various embodiments of the present invention as described herein, reducing the voltage supplied to a load reduces the electrical energy consumed by the load.

[00114] Advantageously, in some embodiments, the system can bypass the effect of the voltage control cell such that the primary conductor has a negligible effect on the magnetic induction in the magnetic core and thereby renders the voltage control cell inoperative.

[00115] Further advantageously, in some embodiments, the system provides electrical protection in the case where there may be a fault in the winding of the voltage control cell. This effectively limits the energy that can be made available to the fault and isolates the cell in a safe state that does not rely on the winding or an associated circuit.

[00116] In another particular advantage of the present invention, using a magnetic core instead of a transformer or VARIAC decreases the physical size and complexity of the system.

[00117] In this specification, adjectives such as first and second, left and right, top and bottom, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step etc.

[00118] The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.

[00119] In this specification, the terms ‘comprises’, ‘comprising’, ‘includes’,‘including’, or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.

Claims

CLAIMS:

1. A system for reducing power consumption in a power supply circuit comprising: a magnetic core defining and at least partially surrounding a passage; a primary conductor connected between an electrical supply and a load, wherein the primary conductor passes through the passage; a switch having a first state and a second state; and a controller connected to: the primary conductor for measuring a load voltage at the load; and the switch, wherein the controller switches the switch between the first state and the second state based on the load voltage to effect a voltage change along the primary conductor as it passes through the passage defined by the magnetic core.

2. The system of claim 1 , wherein the switch has a first pole, a second pole, and a common pole.

3. The system of claim 1 , wherein the magnetic core comprises a winding.

4. The system of claim 3, wherein the winding comprises a wire.

5. The system of claim 3, wherein the winding comprises a first end and a second end wound onto the magnetic core.

6. The system of claim 1 , wherein the primary conductor comprises a first end and a second end.

7. The system of claim 6, wherein the first end of the primary conductor is connected to the electrical supply.

8. The system of claim 6, wherein the second end of the primary conductor is connected to the load.

9. The system of claim 5, wherein the first end of the winding is connected to the first end of the primary conductor, and to the first pole of the switch.

10. The system of claim 9, wherein the second end of the winding is connected to the common pole of the switch.

11. The system of claim 5, wherein the winding is formed such that the passage of the winding, in a direction from the first end to the second end of the winding, passes firstly through the centre of the magnetic core in the same direction as that of the primary conductor as the primary conductor passes through the centre of the magnetic core in a direction from the first end to the second end.

12. The system of claim 2, further comprising a supply neutral conductor.

13. The system of claim 12, wherein the second pole of the switch is connected to the supply neutral conductor.

14. The system of claim 1 , wherein the switch comprises thyristor pairs.

15. The system of claim 1 , wherein the controller comprises a voltage measurement unit for measuring the load voltage.

16. The system of claim 2, wherein the controller comprises a comparator for comparing the load voltage to a voltage set point.

17. The system of claim 1 , wherein the controller comprises a cell switch driver unit for switching the switch between the first state and the second state.

18. The system of claim 1 , wherein, in the first state, the switch connects the common pole to the first pole allowing current of the electrical supply to pass through the primary conductor without any voltage change.

19. The system of claim 16, wherein, in the second state, the switch connects the common pole to the second pole whereby the voltage of the electrical supply is dropped to the voltage set point.

20. The system of claim 1 , further comprising a plurality of magnetic cores.

21. The system of claim 1 , further comprising a plurality of switches.

22. The system of claim 1 , wherein the primary conductor has a continuous cross section.

23. The system of claim 1 , wherein the magnetic core comprises a single magnetic path.

24. The system of claim 1 , wherein the magnetic core forms a magnetic loop.

25. The system of claim 24, wherein the primary conductor passes through the magnetic loop.

26. The system of claim 4, wherein the winding wire has a uniform cross section.

27. The system of claim 3, wherein a cross section of the winding is smaller than a cross section of the primary conductor.

28. The system of claim 1 , wherein the magnetic core is a toroidal core.

29. The system of claim 1 , wherein the magnetic core is a C core.

30. The system of claim 1 , wherein the magnetic core is an R core.

31. The system of claim 1 , wherein the magnetic core comprises laminated electrical steel.

32. The system of claim 1 , wherein the primary conductor includes no electrical taps.

33. The system of claim 3, wherein the winding includes no electrical taps.

34. A method for reducing power consumption in a power supply circuit comprising: connecting a magnetic core to a primary conductor; connecting the primary conductor to an electrical supply and a load; connecting a controller to the primary conductor to measure a load voltage; controlling the voltage on the primary conductor, such that the voltage on the primary conductor is maintained at a set point.