Current sensor system

Abstract

The present disclosure relates to a current sensor system for measuring an electrical measured object dependent on a current in a current-carrying conductor. In one example, a current sensor system includes a first measurement coil and a second measurement coil, where the first measurement coil and the second measurement coil are configured to be positioned relative to each other and the current carrying conductor so as to at least partially surround the current carrying conductor. The system also includes first and second electronic circuitry for actively processing the sensor signals output from the first and second measurement coils such that an electrical measured object may be measured based on a combination of the first and second actively processed signals.

Description

Technical Field

[0001] The present disclosure relates to a system for measuring current in a conductor, and more particularly, to a system for measuring current in a conductor using at least two measuring coils. Background Art

[0002] Current sensors detect and measure the current flowing through a conductor. They are used in many different applications, for example, providing accurate current measurement in utility meters.

[0003] One type of current sensor uses a shunt resistor connected in series with the current-carrying conductor. The voltage drop across the resistor can be measured, and by knowing the resistance of the shunt, the current through the resistor can be calculated. However, at higher currents, the shunt's temperature may increase, changing its resistance and providing an inaccurate current measurement. Furthermore, because the shunt is directly in the path of the measured current, isolation circuitry may be required between the shunt and the sensitive measurement and processing electronics.

[0004] Another type of current sensor uses an electromagnetic transducer to detect changes in the magnetic field generated by a current-carrying conductor. These rate of change field current sensors (sometimes called di / dt current sensors), such as Rogowski coils, do not require any physical connection to the current-carrying conductor and therefore can be isolated from the current-carrying conductor without any further isolation components.

[0005] The rate-of-change current sensor can be implemented on a printed circuit board (PCB), for example, using metal tracks and vias on two layers of the PCB to form a coil. The metal tracks and vias can together form a spiral conductor that is formed into a ring shape to surround an opening in the PCB, through which the current-carrying conductor can pass.

[0006] One category of rate-of-change current sensors is the clamp-on sensor. This category is designed to enable the sensor to be mounted to a live current-carrying conductor so that the current-carrying conductor can be positioned within the center opening of the current sensor. This clamp-on sensor typically splits the sensor coil into two parts such that there is a gap in the coil that allows the current-carrying conductor to pass through the center opening of the sensor. Typically, the current sensor is designed so that when the conductor passes through the gap in the sensor and is positioned in the center opening of the sensor, the two parts of the coil can be brought together and clamped together so that the two parts of the coil effectively form a single coil around (or encircle) the conductor. In the example of a PCB-implemented rate of change current sensor, each of the two parts of the coil can be formed on a separate PCB and then brought together around the current-carrying conductor.

[0007] The individual parts of a clip-on sensor are typically electrically connected passively, for example, via wires and / or connectors, so that the two coil halves can be electrically formed into a single coil. The signal from one part is summed with the other to form a combined signal representing the rate of change of current in the conductor the coil is intended to measure. Alternatively, the current can be determined by integrating the rate-of-change signal. However, these wires and connectors can introduce asymmetries and irregularities, creating unwanted loops in the effectively combined coil, leading to poor electromagnetic field rejection, poor electrostatic coupling, and / or crosstalk with adjacent current sensors or other devices. Consequently, the performance of such clip-on sensors can be poor. Summary of the Invention

[0008] In a first aspect of the present disclosure, a current sensor system for measuring an electrical measurand that depends on a current in a current-carrying conductor is provided, the current sensor system comprising: a first measuring coil; a second measuring coil, wherein the first measuring coil and the second measuring coil are configured to be positioned relative to each other and the current-carrying conductor so as to at least partially surround the current-carrying conductor; a first electronic circuit comprising a first input coupled to the first measuring coil and a first output for coupling to the measuring circuit, the first electronic circuit being configured to generate a first active processing signal based on a first sensor signal received from the first measuring coil and to output the first active processing signal from the first output; and a second electronic circuit comprising a second input coupled to the second measuring coil and a first output for coupling to the measuring circuit, the first electronic circuit being configured to generate a second active processing signal based on a second sensor signal received from the second measuring coil and to output the second active processing signal from the second output, wherein the first active processing signal and the second active processing signal are used to be combined to measure the electrical measurand that depends on the current in the current-carrying conductor.

[0009] In a second aspect of the present disclosure, a measurement system for measuring an electrical object under test that depends on current in a current-carrying conductor is provided, the measurement system comprising: a combination circuit for coupling to a first measuring coil and a second measuring coil arranged to at least partially surround the current-carrying conductor, wherein the combination circuit is configured to generate a combination signal by combining: a first actively processed signal that depends on a first sensor signal output by the first measuring coil; and a second actively processed signal that depends on a second sensor signal output by the second measuring coil; and a measurement circuit coupled to the combination circuit, wherein the measurement circuit is configured to measure the electrical object under test based on the combination signal.

[0010] In a third aspect of the present disclosure, a utility meter for measuring electrical energy supplied by a current-carrying conductor is provided, the utility meter comprising: a first measuring coil; a second measuring coil, wherein the first measuring coil and the second measuring coil are configured to be positioned relative to each other and the current-carrying conductor so as to at least partially surround the current-carrying conductor; a measuring circuit; a first electronic circuit comprising a first input coupled to the first measuring coil and a first output coupled to the measuring circuit, the first electronic circuit being configured to generate a first active processing signal based on a first sensor signal received from the first measuring coil and to output the first active processing signal from the first output; and a second electronic circuit comprising a second input coupled to the second measuring coil and a first output coupled to the measuring circuit, the first electronic circuit being configured to generate a second active processing signal based on a second sensor signal received from the second measuring coil and to output the second active processing signal from the second output, wherein the measuring circuit is configured to measure the electrical energy based on a combination of the first active processing signal and the second active processing signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Aspects of the present disclosure are described, by way of example only, with reference to the following drawings, in which:

[0012] Figure 1 is a schematic diagram of a known Rogowski coil;

[0013] Figure 2A shows the first example of a PCB-implemented clamp-on current sensor;

[0014] Figure 2B Shown from different angles Figure 2A Clamp-on current sensor;

[0015] Figure 2C Shows Figure 2A and 2B Another implementation of the clamp-on current sensor;

[0016] Figure 2D Shows Figure 2A Example circuit diagram of a clamp-on current sensor;

[0017] Figure 3 An example schematic diagram of a system according to one aspect of the present disclosure is shown;

[0018] Figure 4 Shows Figure 3 A schematic diagram of another implementation of the system;

[0019] Figure 5 Shows Figure 3 An example circuit schematic of the system;

[0020] Figure 6 An example circuit schematic is shown, showing Figure 5 details of an example implementation of the circuit;

[0021] Figure 7 An example circuit schematic is shown, showing Figure 5 details of an alternative example implementation of the circuit;

[0022] Figure 8 An example implementation of a utility meter according to one aspect of the present disclosure is shown;

[0023] Figure 9 An example schematic diagram illustrating a system according to another aspect of the present disclosure is shown;

[0024] Figure 10 An example schematic diagram illustrating a system according to another aspect of the present disclosure is shown;

[0025] Figure 11 An example schematic diagram illustrating a system according to another aspect of the present disclosure is shown;

[0026] Figure 12 An example schematic diagram of a system according to another aspect of the present disclosure is shown. DETAILED DESCRIPTION

[0027] Split or clamp-on current sensors allow the current sensor to be mounted around a conductor that might not receive current with a non-split current sensor, but they present a number of disadvantages. The primary disadvantage is reduced measurement accuracy caused by imperfections / asymmetries in the assembled coil and electromagnetic noise induced in the electrical interconnections between the two parts of the current sensor coil, as well as between the two parts of the current sensor winding and the current measurement circuitry that uses the signal output by the current sensor coil to determine the current measurement. Furthermore, it increases the cost and complexity of manufacturing and installation because the two parts of the coil need to be electrically connected together, which requires additional components and reduced manufacturing tolerances to ensure they are electrically connected with positional accuracy, and introduces minimal additional loops that can pick up unwanted magnet areas.

[0028] To address these issues, the inventors developed a split or clamp-on current sensor in which each section of the current sensor has an active electronic circuit to process the signal output from that section. For example, if the sensor is split into two measuring coils, the first measuring coil has a first electronic circuit that processes the sensor signal output by the first measuring coil before sending it to the current measurement circuit. This processing can include at least one of the following: signal amplification; analog-to-digital conversion; or voltage-to-current conversion.

[0029] As a result, the signal is less susceptible to interference from electromagnetic noise (e.g., stray electromagnetic fields from adjacent, unrelated conductors), which should improve the signal-to-noise ratio (SNR) and integrity of the signal received by the current measurement circuit, thereby improving the accuracy of the current measurement. This can be particularly effective when the first electronic circuit is located close to the first measurement coil, so that minimal EM noise pickup occurs in the conductor between the measurement coil and the electronic circuit. The second measurement coil can also have a similar second electronic circuit. The outputs of the two electronic circuits can then be combined to effectively form a virtual larger coil for measuring current in the conductor, with the two coils at least partially encircled together, each coil contributing to the measurement of current in the conductor. This virtual larger coil is created because the two coils are not passively connected together to form a single conductive coil, whose output is measured to measure the current in the current-carrying conductor, as in the previous design. Instead, the independent signal outputs of the active circuits are combined so that the combined signal substantially corresponds to the signal output of the larger coil formed by the two separate coils.

[0030] Before transmitting the signals to where they will be combined (e.g., at the measurement circuit), the amplification performed by the active circuit reduces the input-referred noise of any subsequent EM pickup in the wires and connectors carrying the signals to where they will be combined. For example, if the gain in the active circuit is 30, the same interconnect loop will pick up the same EM noise as in a passively coupled design, but the signal will be 30 times larger, and the relative signal-to-noise ratio will be 30 times better. The analog-to-digital conversion performed by the active circuit before transmitting the signals to the combining location means that when they are transmitted, their form should be virtually immune to electromagnetic pickup. The voltage-to-current conversion performed by the active circuit before transmitting the signals to the combining location (e.g., at the measurement circuit) means that any subsequent EMF voltages picked up in the wires and connectors carrying the signals to the combining location should not first affect the transmitted current signal. These are just some examples of active processing that can be performed to reduce noise sensitivity. Other methods of actively processing the signals picked up by the coils may exist that can reduce sensitivity to noise pickup in the conductors carrying the signals to the combining location.

[0031] The actively processed signals from each coil can be combined at a number of different locations. For example, the actively processed signals from one coil can be transmitted via conductors to the location of the active circuitry of the other coil and combined there. Alternatively, the actively processed signals from both coils can be carried by respective conductors to a third location, such as a processor containing circuitry to receive and combine the signals, somewhere upstream of signal measurement circuitry configured to measure the combined signal.

[0032] The signals can be combined by summing, with or without weighting (i.e., with or without different amounts of gain applied to the coil signals by their respective active circuits). For example, weighting can be applied to at least partially correct for differences in the signal strength of each coil and / or processing path. Applying weighting can allow the coils to be intentionally different (e.g., different sizes), or can be used to correct for inconsistencies that may cause undesirable errors. For example, if the coils are intended to be matched, but are not, in older techniques that passively connect the two coils to form one coil, one part of the coil will be more sensitive than the other, meaning that if the position of the current-carrying conductor relative to each part of the coil changes, the measurement result will be erroneous.

[0033] In the present disclosure, combining the actively processed signals from each coil can occur in the analog or digital domain. Combining in the analog domain can be accomplished by combining the actively processed signals through a passive circuit, for example, using two resistors or through an amplifier, such as an inverting amplifier with two input resistors and a feedback resistor.

[0034] Alternatively, the combined signal can occur in the interconnection between the outputs of the two active circuits. For example, if the active circuit for each coil has an amplifier or voltage-to-current converter with an output impedance, then connecting the outputs of the active circuits together should produce the sum of the two actively processed signals.

[0035] According to the present invention, the active processing signals from two or more coils can be combined (in the analog or digital domain). The individual coils do not have to be identical; they can be of any suitable shape, such as a partial circle (e.g., an arc), a straight line, or any other shape. When the active processing signals from the coils are combined, the resulting virtual combined coil contains or surrounds more current-carrying conductors than each individual coil.

[0036] The location where the combining occurs can be shared with measurements from multiple conductors. For example, there could be a single processor that takes signal streams from multiple coils for each conductor in a three-phase system.

[0037] Each coil outputs a signal representing the di / dt of the current in the current-carrying conductor. To determine the measured value of the current, the signals can be integrated before or after they are combined. Optionally, additional processing, such as high-pass filtering, low-pass filtering, delay, offset, or gain compensation, can be performed in the active circuitry before combining the signals or in other circuitry after combining the signals.

[0038] As a result of the design disclosed herein, not only can measurement accuracy be improved by allowing independent weighting and correction to be applied to each measurement coil contributing to the final current measurement, but sensitivity to EM noise pickup in the interconnections between the measurement coils can also be significantly improved. Consequently, the effects of imperfections / asymmetries in the active combined coils can be reduced, and the integrity of the sensor signal output by the measurement coils can be improved by virtually eliminating EM noise pickup that typically occurs in the inter-coil electrical connections. This further improves the accuracy of current measurements. Furthermore, reducing the requirements for inter-coil electrical connections can reduce manufacturing and installation complexity and cost.

[0039] Figure 1 Figure 1 is a schematic diagram of a known Rogowski coil, an example of a rate of change field current sensor (sometimes called a dI / dt current sensor). To measure the current I(t) flowing through a current-carrying conductor 100, a measuring coil 102 is arranged so that the current-carrying conductor 100 passes through the measuring coil. The measuring coil 102 is wound into a spiral, with the loops or turns of the spiral enclosing a cross-sectional area 104, A. The current-carrying conductor 100 can be, for example, a busbar.

[0040] As the current I(t) in current-carrying conductor 100 changes, the field generated by the current also changes. The positioning of the measuring coil induces a voltage in measuring coil 102 that is proportional to the rate of change of the current dI / dt. Therefore, integrating the output v(t) of the measuring coil provides a value proportional to the current. Each turn or loop of the coil forms a measurement region 104 in a plane perpendicular to the direction of travel of the current-carrying conductor.

[0041] Figure 2A and 2B A first example of a PCB-implemented clamp-on current sensor 200 is shown. The current sensor 200 includes a first PCB 210 on which a first measurement coil 220 is formed (e.g., using conductive traces on two layers of the first PCB 210, such as conductive traces on the upper and lower surfaces of the PCB 210, and conductive vias extending through the first PCB 210 between the upper and lower surfaces, as will be well understood by those skilled in the art). The current sensor 200 also includes a second PCB 230 on which a second measurement coil 240 is formed (e.g., using conductive traces on two layers of the second PCB 230, such as conductive traces on the upper and lower surfaces of the second PCB 230, and conductive vias extending through the second PCB 230 between the upper and lower surfaces, as will be well understood by those skilled in the art). If available, more PCB layers can be used to form the coil, or the layer used for the coil can be internal to other PCB layers (e.g., sandwiched between them).

[0042] Figure 2AThe current sensor 200 is shown from a direction perpendicular or normal to the surfaces of the first PCB 210 and the second PCB 230 (eg, a top view). Figure 2B The current sensor 200 is shown from a direction parallel to the surfaces of the first PCB 210 and the second PCB 230 (eg, a side view).

[0043] Figure 2A and 2B The current sensor 200 is shown positioned around a current carrying conductor 250, such as a wire or busbar. The first PCB 210 and the second PCB 230 can be configured to be positioned relative to each other and the current carrying conductor 250 to surround the current carrying conductor and then clamped in position (e.g., using a clamping mechanism on the first PCB 210 and a clamping mechanism on the second PCB 230 that engage each other to hold the first PCB 210 and the second PCB 230 together). Figure 2A and 2B relative positions as shown, or using some external clamping mechanism such as a frame or housing).

[0044] exist Figure 2B In the example shown, the first PCB 210 and the second PCB 230 are configured to be positioned relative to each other such that the planes of the two PCBs are substantially aligned.

[0045] Figure 2C Another arrangement of the first PCB 210 and the second PCB 220 is shown. Figure 2C The current sensor 200 is shown from a direction parallel to the surfaces of the first PCB 210 and the second PCB 230 (eg, a side view). Figure 2B 2 , except that the first PCB 210 and the second PCB 220 are configured to be positioned relative to each other so as to surround the current carrying conductor 250 and partially overlap each other when viewed from a top-down direction.

[0046] exist Figures 2A to 2C In the example, first measurement coil 220 and second measurement coil 240 are configured to be passively electrically connected to each other, thereby electrically forming a single combined coil. For example, each measurement coil has two ends—one at the beginning of the coil and one at the end. The first end of each coil can be passively electrically connected to the other end, such as via a wire or lead. In one specific example, they can be connected to each other using "pogo pins." In this way, the two measurement coils can electrically form a single coil, such as a single Rogowski coil, surrounding or enclosing the current-carrying conductor 250.

[0047] Figure 2DAn example circuit schematic is shown in which a first measuring coil 220 and a second measuring coil 240 are connected together. A first end 222 of the first measuring coil 220 is connected to a first end 242 of the second measuring coil 240 via a conductor, such as a pogo pin or wire. A second end 224 of the first measuring coil 220 and a second end 244 of the second measuring coil 240 can be connected to a current measurement circuit 270. Current measurement circuit 270 is a circuit configured to determine a measured value of the current in current-carrying conductor 250 based on an analog signal from the first measuring coil 220 (e.g., the signal at the second end 224 of the first measuring coil 220) and an analog signal from the second measuring coil 240 (e.g., the signal at the second end 244 of the second measuring coil 240). In one example, the two analog signals can be combined to form a differential signal. In another example, the second end of one of the measuring coils can be grounded or held at a reference voltage, and the other analog signal received from the other measuring coil can effectively be a single-ended signal. Those skilled in the art will readily appreciate the variety of components and devices that can form part of current measurement circuit 270, and therefore will not be described further herein.

[0048] The inventors have recognized that connecting the first and second measurement coils 220 and 240 as described above has several drawbacks. In many cases, such as using pogo pins, the passive connection between the two coils requires very precise alignment at specific locations. For example, both sides of the pogo pins must be precisely positioned on the first and second PCBs 210 and 230 so that when they are brought together, the first and second coils 220 and 240 are correctly positioned relative to each other. If these are misaligned, this can lead to an imbalance in the signals output by the two coils, thereby affecting the accuracy of the current measurement. Furthermore, the coils comprising the first and second measurement coils 220 and 240 are typically spaced closer together than the conductive connector 260. For example, the minimum dimensions of the PCBs 210 and 230 are typically used to maximize the density of the first and second coils 220 and 240 (e.g., by minimizing the spacing between each coil comprising the first and second coils 220 and 240). However, the conductive connector 260 does not typically match this spacing. As a result, the conductive connector 260 may introduce some asymmetry, non-ideality, and / or irregularities in the coil formed by the first and second measurement coils 220 and 240. This may again affect the accuracy of the current measurement.

[0049] Especially considering that spring pins are the most commonly used form of connection, they typically increase the height of the coil (e.g., in the z-direction, perpendicular to the surface plane of the PCB) and / or the x and / or y displacement. Other connectors with male and female components can be used, but these connectors tend to increase the height and are not consistent with the required coil shape. This increases the overall asymmetry of the coil structure and may also make the coil susceptible to interference (e.g., electromagnetic interfaces), which reduces the current measurement accuracy in the presence of external extraneous magnetic fields (e.g., from currents in adjacent conductors). In addition, spring pins (and other types of interconnects) tend to increase the complexity of the overall manufacturing and assembly of the device. In addition, their positional accuracy can be difficult to control and unpredictable, and can be unreliable.

[0050] Furthermore, the connection between the second ends 224 and 244 of the first and second measurement coils 220 and 240 and the current measurement circuit 270 may be susceptible to interference. For example, due to size (or other) limitations, the current measurement circuit 270 may need to be located relatively far from the first and second measurement coils 220 and 240, perhaps on a third PCB (not shown in the figures). This means that a relatively long electrical connection is required to connect the second ends 224 and 244 to the current measurement circuit 270. This electrical connection is susceptible to signal noise, such as from electromagnetic (EM) interference. Because the signals from the first and second measurement coils 220 and 240 are typically very small (for example, for a 100 ARMS signal at 50 Hz, even if the additional loop associated with the electrical interconnection is only a few millimeters in size), this interference can significantly reduce the signal-to-noise ratio (SNR). Even if the current measurement circuit 270 can be located on either the first PCB 210 or the second PCB 230, relatively close to the second end of the first or second measurement coil 220 or 240, a connection is still required between the second end of the other measurement coil and the current measurement circuit 270, which may be susceptible to signal noise.

[0051] Figure 3 An example schematic diagram of a system 300 according to one aspect of the present disclosure is shown, which the inventors developed to address the above-mentioned shortcomings. The system includes a first PCB 310 on which a first measuring coil 320 is formed and a second PCB 340 on which a second measuring coil 350 is formed. Figures 2A to 2D As in the example described above, the first measurement coil 320 and the second measurement coil 350 are configured to be positioned relative to each other and the current-carrying conductor 380 so as to at least partially surround (or encircle) the current-carrying conductor. The system 300 can be configured such that when positioned around the conductor 380, the first PCB 310 and the second PCB 340 are substantially aligned, similar to Figure 2B, or such that the first and second PCBs 310 and 340 partially overlap each other when viewed from a top-down direction, similar to the attached Figure 2C .

[0052] System 300 also includes a first electronic circuit 330, which includes a first input coupled to first measuring coil 320 and a first output for coupling to measurement circuit 370 (in this example, via combining circuit 390, as described later). For example, a first end of first measuring coil 320 can be coupled to first electronic circuit 330, and a second end of first measuring coil 320 can be coupled to a reference voltage, such as ground. In this case, first electronic circuit 330 receives the first sensor signal from first measuring coil 320 as a single-ended signal. In an alternative embodiment, both the first and second ends of first measuring coil 320 can be coupled to first electronic circuit 330, for example, where first measuring coil 320 includes multiple turns or loops and a loop extending from one end of the coil through the center of the coil to the other end, such that the first and second ends of first measuring coil 320 terminate close to each other (e.g., a well-known feature of a Rogowski coil). In this case, first electronic circuit 330 receives the first sensor signal from first measuring coil 320 as a differential signal. Therefore, it can be seen that first electronic circuit 330 can be very close to the end of first measuring coil 320 to which it is coupled. This should keep to a minimum any signal interference that might be picked up by the conductors coupling the ends of the first measurement coil 320 to the first measurement circuit 330. As a result, even though the signal received by the first electronic circuit 330 may be relatively small (e.g., less than 1 mV RMS for a 100 A RMS signal at 50 Hz), it should still have a good signal-to-noise ratio because the noise pickup from the interference should be very small or zero.

[0053] System 300 also includes a second electronic circuit 360, which includes a second input coupled to second measuring coil 350 and a second output for coupling to measurement circuit 370 (in this example, via combining circuit 390, as described later). For example, the first end of second measuring coil 350 can be coupled to second electronic circuit 360, and the second end of second measuring coil 350 can be coupled to a reference voltage, such as ground. In this case, second electronic circuit 360 receives the second sensor signal from second measuring coil 350 as a single-ended signal. Alternatively, both the first and second ends of second measuring coil 350 can be coupled to second electronic circuit 360, for example, where second measuring coil 350 includes multiple turns or loops and a return line extending from one end of the coil through the center of the coil to the other end, such that the second and first ends of second measuring coil 350 terminate close to each other (e.g., a well-known feature of Rogowski coils). In this case, second electronic circuit 360 receives the second sensor signal from second measuring coil 350 as a differential signal. Therefore, it can be seen that second electronic circuit 330 can be very close to the end of second measuring coil 350 to which it is coupled. This should keep to a minimum any signal interference that might be picked up by the conductors coupling the ends of the second measurement coil 350 to the second measurement circuit 360. As a result, even though the signal received by the second electronic circuit 360 may be relatively small (e.g., less than 1 mVRMS for a 100 A RMS signal at 50 Hz), it should still have a good signal-to-noise ratio because the noise pickup from the interference should be very small or zero.

[0054] The first electronic circuit 330 and the second electronic circuit 360 may each include any one or more of the following circuits / devices: one or more amplifiers; an analog-to-digital converter (ADC); a voltage-to-current (V-2-I) converter. The first electronic circuit 330 and the second electronic circuit 360 may be referred to as "active" circuits because they include one or more powered devices / circuits, rather than circuits consisting solely of passive components / devices (such as wires / traces, resistors, and capacitors).

[0055] In one example, the first electronic circuit 330 and the second electronic circuit 360 can each include one or more amplifiers configured to generate amplified versions of the first sensor signal received from the first measuring coil 320 and the second sensor signal received from the second measuring coil 350. Any suitable type of amplifier circuit can be used. In this case, the first electronic circuit 330 generates and outputs a first active processing signal that is an amplified version of the first sensor signal, and the second electronic circuit 360 generates and outputs a second active processing signal. The combining circuit 390 and / or the current measurement circuit 370 can be located near one of the first electronic circuit 330 or the second electronic circuit 360 (e.g., mounted on the first PCB 310 or the second PCB 370), or can be located relatively far away, such as on a third PCB. Regardless, noise is likely to be picked up in the electrical connections between the first electronic circuit 330 and the combining circuit 390 and / or the current measurement circuit 370, as well as between the second electronic circuit 360 and the combining circuit 390 and / or the circuit 370. However, since the active processing signals transmitted from the first and second electronic circuits 330 and 360 are amplified versions of the first and second sensor signals, the active processing signals transmitted from the first and second electronic circuits 330 and 360 are amplified versions of the first and second sensor signals. Figure 2A and 2D This should improve the integrity and signal-to-noise ratio of the signal received by measurement circuit 370 compared to the example shown. This is because, for the same additional loop of the interconnect, the signal is at an amplified level, and therefore the pickup level is reduced relative to the amplified signal level. Consequently, regardless of where combining circuit 390 and / or current measurement circuit 370 are located, or the conductive routing between the different circuits, improved integrity and signal-to-noise ratio should be achieved, which should improve the accuracy of measurements performed by measurement circuit 370. Combining circuit 390 and current measurement circuit 370 can be implemented separately, such as in separate packages or ICs mounted on the same or different PCBs, or together, such as within the same package or IC. Alternatively, the circuits can be combined within the same IC, such as with one coil locally coupled to a first IC that includes active processing circuitry (e.g., amplification circuitry) and combining circuit 390, and another coil locally coupled to a second IC that includes only active processing circuitry (e.g., amplification circuitry), with its signal then sent to the first IC via the interconnect.

[0056] In another example, the first electronic circuit 330 may include a first ADC to generate a first digital conversion of the first sensor signal, and the second electronic circuit 360 may include a second ADC to generate a second digital conversion of the second sensor signal. In an alternative embodiment, the first electronic circuit 330 and the second electronic circuit 360 may each include an amplifier configured to amplify the first sensor signal and the second sensor signal, respectively, wherein the first ADC and the second ADC are configured to convert amplified versions of the first and second sensor signals, respectively. In either case, the first and second ADCs are configured to generate and output first and second digital signals that are dependent on the first and second sensor signals. Any suitable type of ADC may be used, such as SAR, flash, Σ-Δ, etc.

[0057] By communicating the first and second actively processed signals as digital signals, the signals should be substantially or completely immune to EM noise pickup (e.g., as long as the EM interference level is not so great as to corrupt the logic levels used to transmit the digital signals). Thus, a good SNR should be maintained regardless of where the combining circuit 390 and / or the measurement circuit 370 are located, or the conductive wiring between the circuits.

[0058] In another example, first electronic circuit 330 may include a first V-2-I converter to generate a first current dependent on the voltage of the first sensor signal, and second electronic circuit 360 may include a second V-2-I converter to generate a second current dependent on the voltage of the second sensor signal. Alternatively, first electronic circuit 330 and second electronic circuit 360 may include amplifiers to amplify the first and second sensor signals before they are converted by the first and second V-2-I converters. Current signals are more immune to magnetic noise pickup than voltage signals because the EM effect of the additional interconnecting loop is to generate a voltage that only slightly alters the current due to the output impedance of the V-2-I converter's current source. Therefore, by converting the signals to this form before outputting them from first and second electronic circuits 330 and 360, EM noise immunity should be improved. Consequently, good signal-to-noise ratios (SNRs) should be maintained regardless of where combining circuit 390 and / or current measurement circuit 370 are located, or the conductive routing between the circuits.

[0059] In all of these examples, the term "actively processed signal" is intended to refer to a signal generated by some form of active electronic circuitry (including, but not limited to, amplification and / or digital conversion and / or V-2-I conversion) from the sensor signal output by the measuring coil. It should be noted that multiple types of active processing may occur; for example, amplification may precede the ADC or V-2-I converter. Furthermore, the electronic circuitry may optionally perform one or more additional signal processing functions, either passively or actively, such as signal filtering (high-pass and / or low-pass), integration, signal delay, signal offset, gain compensation, and the like.

[0060] If the combined signal is an analog signal, the measurement circuit 370 may measure the electrical measurand in the analog domain, or may digitally convert the combined signal and measure the electrical measurand in the digital domain.

[0061] In summary, it can be seen that in all examples of first and second electronic circuits 330 and 360, significantly greater flexibility in positioning the measurement circuit 370 is achieved, while also improving (or at least not sacrificing) the signal-to-noise ratio of the signal received at the measurement circuit 370. Furthermore, no electrical coupling is required between the first measurement coil 320 and the second measurement coil 350. Instead, the signals based on the coil outputs are combined elsewhere via the combining circuit 390, which can further reduce signal interference, improve coil symmetry and regularity, and mean that components such as pogo pins are not required. Thus, improved flexibility in positioning the current measurement circuit 370 can be achieved, which can simplify the manufacture and / or installation of the system 300, while maintaining or improving the accuracy of the current measurement due to the good signal-to-noise ratio and good measurement coil symmetry.

[0062] Figure 4 A schematic diagram shows another embodiment of system 300, in which the first and second electronic circuits 330 and 360 are positioned differently relative to the first and second measurement coils 320 and 350. The first and second electronic circuits 330 and 360 can be located anywhere on the first and second PCBs 310 and 340, typically depending on the specific design of the first and second measurement coils 320 and 350, such as near the ends of the measurement coils to which the electronic circuits are coupled. In this example, coils 320 and 350 can be differential in nature, with the balanced pos (positive) coil carried counterclockwise from the electronic circuits and the minus (negative) coil carried clockwise therefrom to produce differential pickup. A potential advantage of this arrangement is that the electronic circuits can be positioned away from each board edge, thereby allowing the boards to be abutted against each other in a closer, more symmetrical manner for virtual coils.

[0063] Figure 5A schematic circuit diagram of system 300 is shown. In this example, both ends of first measurement coil 320 are coupled to first electronic circuit 330, and both ends of second measurement coil 350 are connected to second electronic circuit 360. The measurement coils can be made from multiple parts (for example, using loop wire, as is well known in Rogowski coils). A bias voltage or ground connection can be present in the middle of each coil, so that the signals received at first electronic circuit 330 and second electronic circuit 360 are differential with respect to the bias voltage or ground. As a result, first electronic circuit 330 and second electronic circuit 360 receive the first sensor signal and the second sensor signal as differential signals. Alternatively, system 300 can be configured so that the first and second sensor signals are single-ended, as described above. Furthermore, while the outputs of the first and second electronic circuits are shown as single-ended, they can also be differential. Furthermore, while the output of combination circuit 390 is shown as single-ended, it can also be differential.

[0064] The combining circuit 390 is arranged to generate a combined signal by combining the first and second actively processed signals and output the combined signal to the measurement circuit 370, thereby coupling the output of the first electronic circuit 330 to the measurement circuit 330 and coupling the output of the second electronic circuit 360 to the measurement circuit 370. For example, the combined signal may be the sum or average of the first and second actively processed signals, and the combining circuit 390 may include any suitable passive and / or active circuitry configured for this purpose.

[0065] Figure 6 An example implementation of a combination circuit 390 is shown, comprising an inverting amplifier formed by an operational amplifier A and resistors R1, R2, and Rf. Thus, the combined signal output by combination circuit 390 is a weighted average of the simulated first active processing signal and the simulated second active processing signal, with the weighting determined by the relative sizes of R1 and R2. It will be appreciated that any other suitable amplifier circuit, such as an inverting or non-inverting amplifier, or one or more transistors appropriately biased with resistors, may be used. In this example, combination circuit 390 is an active circuit.

[0066] In this example, Vcm is the common-mode voltage of the first and second coils 320, 350, for example, where one end (e.g., the return end) of each coil is coupled to a reference voltage or ground, such that the analog signals output by the first and third coils 320, 350 are differential with respect to Vcm. In this example, the gain applied to the first actively processed signal is determined by the relative sizes of R1 and Rf, while the gain applied to the second actively processed signal is determined by the respective sizes of R2 and Rf. The amplified output is a weighted average of the two actively processed signals, where the weighting is determined by the relative gains applied to each signal.

[0067] Figure 7 Another example implementation of a combining circuit 390 is shown, comprising two resistors R3 and R4 formed as a voltage divider. If R3 and R4 are matched (i.e., have the same resistance), the combined signal is the average of the simulated first active process signal and the simulated second active process signal. Alternatively, R3 and R4 may not be matched, but may have different resistances, such that the combined signal is effectively a weighted average of the first and second active process signals. This may be done, for example, to correct for an imbalance inherent in the relative design of the first and second coils 320 and 350 (e.g., one coil is larger than the other), or to correct for imbalances caused by imperfections in the manufacturing of the coils 320, 350 and / or the electronic circuits 330, 360. To this end, one or both resistors may be variable so that the weighting can be adjusted during system calibration. In this example, combining circuit 390 is a passive circuit.

[0068] In the alternative, if the first and second electronic circuits 330, 360 have high output impedance (e.g., if they have V-2-I converters or high output impedance amplifiers), the combining circuit 390 may simply connect the outputs of the first and third electronic circuits 330 and 360 together to produce a combined signal that is the sum of the first and fourth active processing circuits.

[0069] In another alternative, if both the first and second active processing signals are analog, the combining circuit 390 may include one or more analog-to-digital circuits, ADCs (e.g., one ADC shared between the first and second active processing signals using a multiplexer, or one ADC for each of the first and second active processing signals), and digital circuits to combine the two digital signals, such as by averaging or summing them. Alternatively, if the first and second active processing signals received by the combining circuit 390 are digital signals, the combining circuit 390 may simply include digital circuits to combine the two digital signals, such as by averaging or summing them. In both cases, the combined signal is a digital signal, and the combining circuit 390 is an active circuit.

[0070] The measurement circuit 370 may be configured to measure any one or more electrical measurands that depend on the current in the current-carrying conductor 380. For example, it may be configured to measure any one or more of the following:

[0071] Calculating the rate of change of current in the current-carrying conductor 380 using the received combined signal;

[0072] Determining the magnitude (and optionally the polarity) of the current in the current-carrying conductor 380 by integrating the received combined signal;

[0073] Determining the electrical energy associated with the current in the current carrying conductor 380 , for example, by determining the magnitude of the current in the current carrying conductor 380 and multiplying it by the voltage measurement;

[0074] • Determine the power associated with the current in the current carrying conductor 380, for example, by determining the energy per unit time.

[0075] Thus, it can be seen that the system 300 of the present disclosure can be used as part of a utility meter configured to measure electrical energy consumption for billing purposes.

[0076] Figure 8 An example implementation of a utility meter 800 is shown. Current-carrying conductor 380 is not part of utility meter 800, but rather is a conductor that carries the current measured by utility meter 800. For example, it may be a "live" conductor that supplies power to a residence or industrial building. Measurement circuit 370 is also configured to receive a voltage signal 810 indicative of the voltage associated with the current in conductor 380, allowing measurement circuit 810 to measure the energy and / or power provided by the current in conductor 380. In this example, utility meter 800 measures the current in only one conductor, but it will be appreciated that it can be configured to measure current in multiple conductors, such as the live and neutral conductors supplying power to a residence or industrial building, or in each phase conductor of a multi-phase power supply (in which case, the signals for each phase can be combined at the same location to generate a combined signal for each phase, or the combined signal for each phase can be generated by a separate combining circuit at a separate location). In these examples, first and second measurement coils can be mounted on each conductor to be measured, and each pair of measurement coils can have an associated combining circuit 390. In this way, the measurement circuit 370 can receive a combined signal from each pair of measurement coils and can thus measure the current in each conductor.

[0077] Additional or alternative uses of electrical measurements include, for example, any one or more of motor control, condition-based monitoring, fault detection, etc. Thus, measurement circuit 370 may form part of a wider system, or other systems may use measurements output by measurement circuit 370 .

[0078] It will be readily apparent to those skilled in the art that various changes or modifications may be made to the above-described aspects of the present disclosure without departing from the scope of the present disclosure.

[0079] Figure 9 An example schematic diagram of a system 900 according to an alternative implementation is shown. Figure 3 and Figure 4The example in [ 1 ] is very similar, but does not include a dedicated second electronic circuit 360. Instead, the second measurement coil 350 is coupled to a measurement circuit 970, ideally as close as possible to the coil end of the second measurement winding 350. In this example, the measurement circuit 970 is mounted on the second PCB 340 and effectively comprises the second electronic circuit 360, the combining circuit 390, and the measurement circuit 370. It includes circuitry equivalent to the second electronic circuit 360, allowing the first and second sensor signals to be processed in an equivalent manner (e.g., converted to digital or current signals) before being combined. As described above, the electrical coupling between the first electronic circuit 330 and the measurement circuit 970 should be largely or completely immune to noise pickup, and by positioning the measurement circuit 970 close to the second measurement coil 350, the signal-to-noise ratio of the second sensor signal should also be good. Furthermore, as described above, no electrical coupling is required between the first measurement coil 320 and the second measurement coil 350, which further reduces signal interference, improves coil symmetry and regularity, and eliminates the need for components such as pogo pins. Thus, the measurement accuracy of the electrical measurand should be improved due to a good signal-to-noise ratio and good measurement coil symmetry, while reducing complexity and cost by not requiring an electrical connection between the first and second measurement coils 320 and 350 .

[0080] In each of the above examples, the signals from each of the measurement coils 320 and 350 are combined. As a result, the combined signal effectively represents the signal from a virtual coil corresponding to the combination of the two measurement coils 320 and 360, while in reality, two electrically separate measurement coils each partially surround the current-carrying conductor 380. As previously described, an electrical connection between the two measurement coils 320 and 350 is therefore not required, which can reduce the cost and complexity of manufacturing and installation and improve the accuracy of current measurement.

[0081] Furthermore, it is possible to apply different weightings to the measurement signals corresponding to each measurement coil, which can have a number of benefits. In one example, it can be used to correct for imperfections in the first and second measurement coils 320 and 350. For example, the first PCB 310 and the second PCB 340 may be manufactured with slightly different thicknesses, meaning that the coil sizes of the first measurement coil 320 and the second measurement coil 350 will be different, resulting in different levels of induced signals in the coils. This can be detected during device calibration and corrected by changing the relative weighting of the two signals combined by the current measurement circuit 370, 970 to measure current (e.g., to 49:51 or 52:48, etc.). The relative weighting can be adjusted by any one or more of: adjusting the relative amplifier gains of the first and second electronic circuits 330, 360; adjusting the digital conversion performed by the first and second electronic circuits 330, 360 (e.g., by changing a converter reference value or by applying a multiplication after the conversion); and / or by adjusting the V-2-I conversion performed by the first and second electronic circuits 330, 360 (e.g., by changing a current reference value) and / or adjusting the relative weights of the active processing signals at the combining circuit 390 prior to combining, either digitally or in analog fashion.

[0082] Another benefit of the flexibility provided by electrically combining the signals in this manner is that the first and second measurement coils 320, 350 can be intentionally sized differently. The first measurement coil 320 is designed to align with or encompass a first perimeter or circumferential portion (or first arc) of the current-carrying conductor 380, and the second measurement coil 350 is designed to align with or encompass a second perimeter or circumferential portion (or second arc) of the current-carrying conductor 380. In the example described above, the first and second perimeter portions are of equal size (e.g., each perimeter portion is 180 degrees). However, in alternative embodiments, the first and second perimeter portions can be sized differently.

[0083] Figure 10An example schematic diagram of a system 1000 according to one aspect of the present disclosure is shown, in which the first and second perimeter portions have different sizes. In this example, each of the first measurement coil 320 and the second measurement coil 350 partially surrounds a current-carrying conductor 380. However, the first measurement coil 320 partially surrounds more of the current-carrying conductor 380 than the second measurement coil 350. In other words, the first perimeter or circumferential portion (or first arc) of the current-carrying conductor 380 surrounded by the first measurement coil 320 is larger than the second perimeter or circumferential portion (or second arc) of the current-carrying conductor 380 partially surrounded by the second measurement coil 350. In other words, the angle enclosed by the first measurement coil 320 is larger than the angle enclosed by the second measurement coil 350. The sensor signals output by the first and second measurement coils 320 and 350 can then be appropriately weighted (e.g., 75:25) by the first and second electronic circuits 330 and 360 and / or the combining circuit 390. This allows for greater flexibility in measuring coil design, for example allowing a design to be created that fits a particular space, such that a measuring coil can be mounted around a current carrying conductor 370 where previously it would not have been possible due to physical space limitations.

[0084] For example, in each of the above examples, the current measurement system is configured so that when the first and second measurement coils 320 and 350 are in position relative to the current carrying conductor 380, they together completely surround or encircle the current carrying conductor 380 (i.e., 360 degrees around the current carrying conductor). Figure 2B As shown), the two measuring coils can be aligned 360 degrees together. In the case of overlapping PCBs (as Figure 2C As shown, the two measuring coils may be directed together over 360 degrees. However, in an alternative embodiment, they may only partially surround the current-carrying conductor 380, for example, they may be directed together over less than 360 degrees. For example, they may be directed together over 300 degrees, 350 degrees, etc.

[0085] Figure 11 An example system 1100 according to one aspect of the present disclosure is shown, wherein two measurement coils are each configured to partially surround a conductor 380 and partially, but not completely, surround the conductor 380. Furthermore, in this example, each coil is not annular in shape but rather oriented linearly. System 1100 includes a first coil 1120 formed on a first PCB 1110 and a second coil 1150 formed on a second PCB 1140.

[0086] In each of the above examples, the first and second measurement coils are configured and positioned so that they each subtend or partially surround a corresponding perimeter portion of the current-carrying conductor and, together, subtend a combined perimeter portion of the current-carrying conductor 380 that is larger than the perimeter portion subtended by each measurement coil. This is regardless of whether the perimeter portions subtended by each measurement coil are the same or different, or whether the combined perimeter portion completely or only partially surrounds the current-carrying conductor 380.

[0087] Additionally or alternatively, the current measurement system may include more than two measurement coils. For example, it may include three or more measurement coils, each implemented on its own PCB and configured to be positioned relative to each other and the current-carrying conductor 380 so as to at least partially surround the current-carrying conductor 380. In this case, each measurement coil may have corresponding electronic circuitry as described above.

[0088] In each of the above examples, there is a single current sensor coil comprised of two or more individual measuring coils 320 and 350. Alternatively, the current measurement system can include two or more current sensor coils, each comprised of two or more individual measuring coils 320 and 350 implemented on a respective PCB. As described above, each measuring coil can have corresponding electronic circuitry (or all but one measuring coil can have corresponding electronic circuitry), the output of which can be used by the measurement circuitry 370, 570 to determine a measurement value of the object under test. An example of this would be one current measuring coil that spirals around a current-carrying conductor 380 in a clockwise spiral, and another current measuring coil that spirals around the current-carrying conductor 380 in a counterclockwise spiral.

[0089] For example, Figure 12An implementation of a system 1200 according to one aspect of the present disclosure is shown. In this example, four measurement coils are arranged around a current-carrying conductor 380: a first measurement coil on a first PCB 310, a second measurement coil on a second PCB 340, a third measurement coil on a third PCB 1240 (essentially a replica of the second measurement winding, but with the turns rotated in the opposite direction), and a fourth measurement coil on a fourth PCB 1210 (essentially a replica of the first measurement winding, but with the turns rotated in a different direction). The third electronic circuit 1260 is essentially a replica of the second electronic circuit 360, and the fourth electronic circuit 1230 is essentially a replica of the first electronic circuit 330. Combining circuit 390 combines the active processing signals from all four electronic circuits to generate a combined signal, or combines the first and second active processing signals to generate a first combined signal and combines the third and fourth active processing signals (output by the third and first electronic circuits 1260 and 1230) to generate a second combined signal. In the latter case, measurement circuit 370 can use the first and second combined signals to measure the electrical device under test.

[0090] In each of the above examples, the measuring coil is implemented on a PCB. However, the principles of the present disclosure can be applied to current measuring coils implemented in any other manner.

[0091] Furthermore, in most of the examples described above, combining circuit 390 and measurement circuit 370 are separate circuits. However, they can be implemented within the same package or IC, in which case they can be considered a single circuit. Furthermore, in some cases, the function of combining the first and second active processing signals can be performed by measurement circuit 370, for example, where the first and second active processing signals are digital signals and measurement circuit 370 combines them as part of its measurement function.

[0092] In the examples above, the measurement coils are located within the PCB substrate. Alternatively, they can be formed on or within other types of substrates, or using other types of windings. For example, the windings can be formed in a flexible manner, or implemented using different substrate materials, or manufactured by wrapping wires around a mechanical structure.

[0093] The term "coupled" as used above includes a direct electrical connection between two components as well as an indirect electrical connection in which two components are electrically connected to each other through one or more intermediate components.

[0094] aspect

[0095] Non-limiting aspects of the disclosure are listed in the following numbered clauses.

[0096] 1. A current sensor system for measuring an electrical measurand that is dependent on a current in a current-carrying conductor, the current sensor system comprising:

[0097] a first measuring coil;

[0098] a second measuring coil, wherein the first measuring coil and the second measuring coil are configured to be positioned relative to each other and the current-carrying conductor so as to at least partially surround the current-carrying conductor;

[0099] a first electronic circuit comprising a first input coupled to the first measuring coil and a first output for coupling to a measuring circuit, the first electronic circuit being configured to generate a first active processing signal based on a first sensor signal received from the first measuring coil and to output the first active processing signal from the first output;

[0100] a second electronic circuit comprising a second input coupled to the second measuring coil and a first output for coupling to the measuring circuit, the first electronic circuit being configured to generate a second active processing signal based on a second sensor signal received from the second measuring coil and to output the second active processing signal from the second output,

[0101] The first actively processed signal and the second actively processed signal are used in combination to measure an electrical object under test that depends on the current in the current-carrying conductor.

[0102] 2. The current sensor system of clause 1, wherein the first electronic circuit comprises a first amplifier configured to generate an amplified version of the first sensor signal;

[0103] The second electronic circuit includes a second amplifier configured to generate an amplified version of the second sensor signal.

[0104] 3. The current sensor system of clause 2, wherein a gain of the first amplifier is the same as a gain of the second amplifier.

[0105] 4. The current sensor system of clause 2, wherein a gain of the first amplifier is different from a gain of the second amplifier.

[0106] 5. A current sensor system according to any preceding clause, wherein the first electronic circuit comprises a first analog-to-digital converter ADC arranged to generate a first digital signal dependent on the first sensor signal;

[0107] The second electronic circuit comprises a second analog-to-digital converter ADC arranged to generate a second digital signal dependent on the second sensor signal.

[0108] 6. A current sensor system according to any preceding clause, wherein the first electronic circuit comprises a first voltage-to-current converter, wherein the first sensor signal is a voltage signal, and wherein the first voltage-to-current converter is configured to generate a first current signal that is dependent on the first sensor signal;

[0109] The second electronic circuit includes a second voltage-to-current converter, wherein the second sensor signal is a voltage signal, and the second voltage-to-current converter is configured to generate a second current signal that is dependent on the second sensor signal.

[0110] 7. A current sensor system according to any preceding clause, further comprising:

[0111] a combining circuit for coupling a first output of the first electronic circuit to the measurement circuit and coupling a second output of the second electronic circuit to the measurement circuit,

[0112] The combining circuit is configured to generate a combined signal for output to the measurement circuit by combining the first active processing signal and the second active processing signal.

[0113] 8. The current sensor system of clause 7, wherein the combining circuit is a passive circuit configured to passively combine the first actively processed signal and the second actively processed signal.

[0114] 9. The current sensor system of clause 7, wherein the combining circuit is an active circuit configured to actively combine the first actively processed signal and the second actively processed signal.

[0115] 10. The current sensor system of clause 9, wherein the combined circuit comprises an amplifier comprising:

[0116] an input for receiving the first actively processed signal and the second actively processed signal;

[0117] output, used to output the first combined signal.

[0118] 11. The current sensor system of clause 7, wherein the combining circuit comprises a digital circuit for digitally combining the first actively processed signal and the second actively processed signal.

[0119] 12. A current sensor system according to any of the preceding clauses, wherein the first measuring coil is formed on a first printed circuit board PCB, and

[0120] The second measuring coil is formed on a second PCB.

[0121] 13. The current sensor system of clause 12, wherein the first electronic circuit is on the first PCB and the second electronic circuit is on the second PCB.

[0122] 14. A current sensor system according to clause 12 or 13, wherein the first PCB comprises a first clamping mechanism and the second PCB comprises a second clamping mechanism,

[0123] The first clamping mechanism and the second clamping mechanism are adapted to engage with each other so as to hold the first measuring coil and the second measuring coil in place.

[0124] 15. A current sensor system according to any preceding clause, further comprising:

[0125] The measurement circuit is coupled to the first electronic circuit and the second electronic circuit and is configured to measure an electrical measurand that is dependent on a current in the current-carrying conductor based on a combination of the first active processing signal and the second active processing signal.

[0126] 16. A current sensor system according to any preceding clause, wherein the electrical measurand that is dependent on the current in the current-carrying conductor comprises any one or more of:

[0127] the rate of change of current in the current-carrying conductor;

[0128] the amplitude of the current in the current-carrying conductor;

[0129] electrical energy associated with the current in said current-carrying conductor;

[0130] The electrical force associated with the current in the current-carrying conductor.

[0131] 17. A current sensor system according to any preceding clause, wherein said first measuring coil is arranged opposite a first peripheral portion of said current carrying conductor;

[0132] The second measuring coil is configured to be opposite to a second peripheral portion of the current-carrying conductor.

[0133] 18. A current sensor system according to clause 17, wherein the first measuring coil and the second measuring coil are configured so that when they are positioned relative to the current-carrying conductor in use, they are together opposite a combined peripheral portion of the current-carrying conductor, the combined peripheral portion being larger than each of the first peripheral portion and the second peripheral portion.

[0134] 19. The current sensor system according to clause 17 or 18, wherein the size of the first peripheral portion is equal to the size of the second peripheral portion.

[0135] 20. A measurement system for measuring an electrical measurand that is dependent on current in a current-carrying conductor, the measurement system comprising:

[0136] a combining circuit for coupling to a first measuring coil and a second measuring coil arranged to at least partially surround the current-carrying conductor, wherein the combining circuit is configured to generate a combined signal by combining:

[0137] a first actively processed signal, dependent on a first sensor signal output by the first measuring coil;

[0138] a second actively processed signal, dependent on a second sensor signal output by the second measuring coil;

[0139] A measurement circuit is coupled to the combining circuit, wherein the measurement circuit is configured to measure the electrical measurand based on the combined signal.

[0140] 21. A utility meter for measuring electrical energy supplied by a current-carrying conductor, the utility meter comprising:

[0141] a first measuring coil;

[0142] a second measuring coil, wherein the first measuring coil and the second measuring coil are configured to be positioned relative to each other and the current-carrying conductor so as to at least partially surround the current-carrying conductor;

[0143] Measuring circuit;

[0144] a first electronic circuit comprising a first input coupled to the first measuring coil and a first output coupled to the measuring circuit, the first electronic circuit being configured to generate a first active processing signal based on a first sensor signal received from the first measuring coil and to output the first active processing signal from the first output;

[0145] a second electronic circuit comprising a second input coupled to the second measuring coil and a first output coupled to the measuring circuit, the first electronic circuit being configured to generate a second active processing signal based on a second sensor signal received from the second measuring coil and to output the second active processing signal from the second output,

[0146] Wherein the measurement circuit is configured to measure the electrical energy based on a combination of the first actively processed signal and the second actively processed signal.

[0147] 22. The utility meter of clause 21, further comprising a combination circuit arranged to couple the first electronic circuit to the measurement circuit and to couple the second electronic circuit to the measurement circuit, wherein the combination circuit is configured to:

[0148] A combined signal is generated for output to the measurement circuit by combining the first actively processed signal and the second actively processed signal.

Claims

1. A current sensor system for measuring an electrical measurand that is dependent on a current in a current-carrying conductor, the current sensor system comprising: a first measuring coil; a second measuring coil, wherein the first measuring coil and the second measuring coil are configured to be positioned relative to each other and the current-carrying conductor so as to at least partially surround the current-carrying conductor; a first electronic circuit comprising a first input coupled to the first measuring coil and a first output for coupling to a measuring circuit, the first electronic circuit being configured to generate a first active processing signal based on a first sensor signal received from the first measuring coil and to output the first active processing signal from the first output; and a second electronic circuit comprising a second input coupled to the second measuring coil and a first output for coupling to the measuring circuit, the first electronic circuit being configured to generate a second active processing signal based on a second sensor signal received from the second measuring coil and to output the second active processing signal from the second output, The first actively processed signal and the second actively processed signal are used in combination to measure an electrical object under test that depends on the current in the current-carrying conductor.

2. The current sensor system of claim 1 , wherein the first electronic circuit comprises a first amplifier configured to generate an amplified version of the first sensor signal, and The second electronic circuit includes a second amplifier configured to generate an amplified version of the second sensor signal. 3 . The current sensor system of claim 2 , wherein a gain of the first amplifier is the same as a gain of the second amplifier. The current sensor system of claim 2 , wherein a gain of the first amplifier is different from a gain of the second amplifier.

5. The current sensor system according to claim 1 , wherein the first electronic circuit comprises a first analog-to-digital converter (ADC) arranged to generate a first digital signal dependent on the first sensor signal, and The second electronic circuit comprises a second analog-to-digital converter ADC arranged to generate a second digital signal dependent on the second sensor signal.

6. The current sensor system according to claim 1 , wherein the first electronic circuit comprises a first voltage-to-current converter, wherein the first sensor signal is a voltage signal, and the first voltage-to-current converter is configured to generate a first current signal that is dependent on the first sensor signal, and The second electronic circuit includes a second voltage-to-current converter, wherein the second sensor signal is a voltage signal, and the second voltage-to-current converter is configured to generate a second current signal that is dependent on the second sensor signal.

7. The current sensor system according to claim 1 , further comprising: a combining circuit for coupling a first output of the first electronic circuit to the measurement circuit and coupling a second output of the second electronic circuit to the measurement circuit, The combining circuit is configured to generate a combined signal for output to the measurement circuit by combining the first active processing signal and the second active processing signal. 8 . The current sensor system of claim 7 , wherein the combining circuit is a passive circuit configured to passively combine the first actively processed signal and the second actively processed signal. 9 . The current sensor system of claim 7 , wherein the combining circuit is an active circuit configured to actively combine the first actively processed signal and the second actively processed signal.

10. The current sensor system of claim 9, wherein the combination circuit comprises an amplifier, the amplifier comprising: an input for receiving the first actively processed signal and the second actively processed signal; as well as output, used to output the first combined signal.

11. The current sensor system of claim 7, wherein the combining circuit comprises digital circuitry for digitally combining the first and second actively processed signals.

12. The current sensor system according to claim 1, wherein the first measuring coil is formed on a first printed circuit board PCB, and The second measuring coil is formed on a second PCB. 13 . The current sensor system of claim 12 , wherein the first electronic circuit is on the first PCB and the second electronic circuit is on the second PCB.

14. The current sensor system of claim 1 , further comprising: The measurement circuit is coupled to the first electronic circuit and the second electronic circuit and is configured to measure an electrical measurand that is dependent on a current in the current-carrying conductor based on a combination of the first active processing signal and the second active processing signal.

15. The current sensor system of claim 1, wherein the electrical measurand that is dependent on the current in the current-carrying conductor comprises any one or more of the following: the rate of change of current in the current-carrying conductor; the amplitude of the current in the current-carrying conductor; electrical energy associated with the current in said current-carrying conductor; The electrical force associated with the current in the current-carrying conductor.

16. The current sensor system of claim 1, wherein the first measuring coil is configured to oppose a first peripheral portion of the current-carrying conductor; and The second measuring coil is configured to be opposite to a second peripheral portion of the current-carrying conductor.

17. A current sensor system according to claim 16, wherein the first measuring coil and the second measuring coil are configured so that when they are positioned relative to the current carrying conductor in use, they together oppose a combined peripheral portion of the current carrying conductor, the combined peripheral portion being larger than each of the first peripheral portion and the second peripheral portion.

18. A measurement system for measuring an electrical measurand that is dependent on current in a current-carrying conductor, the measurement system comprising: a combining circuit for coupling to a first measuring coil and a second measuring coil arranged to at least partially surround the current-carrying conductor, wherein the combining circuit is configured to generate a combined signal by combining: a first actively processed signal, dependent on a first sensor signal output by the first measuring coil; as well as a second actively processed signal, dependent on a second sensor signal output by the second measuring coil; and A measurement circuit is coupled to the combining circuit, wherein the measurement circuit is configured to measure the electrical measurand based on the combined signal.

19. A utility meter for measuring electrical energy supplied by a current-carrying conductor, the utility meter comprising: a first measuring coil; a second measuring coil, wherein the first measuring coil and the second measuring coil are configured to be positioned relative to each other and the current-carrying conductor so as to at least partially surround the current-carrying conductor; Measuring circuit; a first electronic circuit comprising a first input coupled to the first measuring coil and a first output coupled to the measuring circuit, the first electronic circuit being configured to generate a first active processing signal based on a first sensor signal received from the first measuring coil and to output the first active processing signal from the first output; and a second electronic circuit comprising a second input coupled to the second measuring coil and a first output coupled to the measuring circuit, the first electronic circuit being configured to generate a second active processing signal based on a second sensor signal received from the second measuring coil and to output the second active processing signal from the second output, Wherein the measurement circuit is configured to measure the electrical energy based on a combination of the first actively processed signal and the second actively processed signal.

20. The utility meter of claim 19, further comprising a combination circuit arranged to couple the first electronic circuit to the measurement circuit and to couple the second electronic circuit to the measurement circuit, wherein the combination circuit is configured to: A combined signal is generated for output to the measurement circuit by combining the first actively processed signal and the second actively processed signal.

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