Electric energy meter

Abstract

An apparatus is described that includes a DC electric meter (62). The DC electric meter (62) includes a current sensor (1) or the DC electric meter (62) is connected to the current sensor (1). The current sensor (1) includes a busbar connector (2) that includes a first portion (3) connected to a third portion (4) via a second portion (5). The temperature coefficient of electrical resistance of the material forming the second portion (5) is less than the temperature coefficient of electrical resistance of the materials forming the first portion (3) and the third portion (4), respectively. The second portion (5) includes a body (6) integrally formed with a first connecting member (7a) and a second connecting member (7b). Each connection member (7a, 7b) has a proximal end (8a, 8b) mating with the body (6) and a distal end (9a, 9b) electrically coupled to a conductive element (10a, 10b) supported on the substrate (11) and coupled to a circuit (12) configured to measure a voltage between the first connection member (7a) and the second connection member (7b). The current sensor (1) is configured such that when a first temperature difference (δT1) exists between the proximal ends (8a, 8b) of the first connection member (7a) and the second connection member (7b), a second temperature difference (δT2) between the respective distal ends (9a, 9b) is less than or equal to 50% of the first temperature difference (δT1).

Description

[Technical field]

[0001] The present invention relates to a watthour meter, and more particularly to a watthour meter capable of measuring DC power. [Background technology]

[0002] As interest in direct current (DC) power grows, so does the importance of watt-hour meters that can measure DC power, as opposed to alternating current (AC) power. However, DC watt-hour meter technology is not as advanced as AC watt-hour meters and has not yet been widely adopted by the public. Furthermore, existing AC watt-hour meters tend to perform poorly with DC.

[0003] Existing DC meters can be susceptible to measurement errors when the thermal environment of the current-carrying busbar is not uniform or symmetrical, as is often the case in practice.

[0004] US2011 / 0267038A1 describes current shunt sensors and current shunt sensor assembly configurations that can be used in single / split-phase and polyphase energy metering applications. WO2013 / 093714A1 describes methods and circuits for reducing errors in current shunts. WO2020 / 249490A1 describes a DC meter for electric vehicle charging stations. Summary of the Invention

[0005] According to a first aspect of the present invention, there is provided an apparatus including a DC electric meter. The DC electric meter includes a current sensor or the DC electric meter is connected to the current sensor. The current sensor includes a bus bar connector including a first portion connected to a third portion via a second portion. A temperature coefficient of electrical resistance of a material forming the second portion is less than a temperature coefficient of electrical resistance of a material forming the first portion and the third portion, respectively. The second portion includes a body integrally formed with the first and second connecting members. Each connecting member has a proximal end mating with the body and a distal end electrically coupled to a conductive element supported on a substrate and coupled to a circuit configured to measure a voltage between the first and second connecting members. The current sensor is configured such that when a first temperature difference exists between the respective proximal ends of the first and second connecting members, a second temperature difference between the respective distal ends is less than or equal to 50% of the first temperature difference.

[0006] A distal end of the first connecting member may be connected to the first conductive element, and a distal end of the second connecting member may be connected to the second conductive element.

[0007] The first temperature difference may result from one or more of Joule heating in the busbar connector, heat flux between the first portion and the external environment and / or connected portion, and heat flux between the third portion and the external environment and / or connected portion.

[0008] The second temperature difference may be 40% or less than the first temperature difference. The second temperature difference may be 30% or less than the first temperature difference. The second temperature difference may be 20% or less than the first temperature difference. The second temperature difference may be 10% or less than the first temperature difference.

[0009] The first connecting member may extend along a first path between the proximal end and the distal end, the first path having a first length. A first width of the first connecting member at each point along the first path may be a maximum dimension of the first connecting member perpendicular to the first path at that point. The first length may be three times or more than a maximum of the first width along the first path. The second connecting member may extend along a second path between the proximal end and the distal end, the second path having a second length. A second width of the second connecting member at each point along the second path may be a maximum dimension of the second connecting member perpendicular to the second path at that point. The second length may be three times or more than a maximum of the second width along the second path.

[0010] Thus, the elongated nature of the connecting members means that the distal ends of the first and second connecting members are more thermally isolated from the proximal ends and may approach isothermal temperature with each other due to thermal conduction through the substrate, which helps to reduce asymmetry in the thermal electromotive forces (EMFs) generated at the interfaces of the first and second connecting members and their respective conductive elements.

[0011] Furthermore, elongating the first and second members increases the surface heat loss along the respective first and second paths, which may result in the temperature at the distal end approaching equilibrium with the ambient temperature.

[0012] The first path may be straight. The first path may be curved. The first path may include one or more angles. The first path may be serpentine. The second path may be straight. The second path may be curved. The second path may include one or more angles. The second path may be serpentine.

[0013] The first / second length may be 6 times or more than the maximum width of the first / second connection member perpendicular to the first / second path. The first / second length may be 6 times or more than the maximum width of the first / second connection member perpendicular to the first / second path. The first / second length may be 7 times or more than the maximum width of the first / second connection member perpendicular to the first / second path. The first / second length may be 8 times or more than the maximum width of the first / second connection member perpendicular to the first / second path. The first / second length may be 9 times or more than the maximum width of the first / second connection member perpendicular to the first / second path. The first / second length may be 10 times or more than the maximum width of the first / second connection member perpendicular to the first / second path.

[0014] The first and second connecting members are preferably mirror images (equivalently symmetrical) about a centerline of the body between the first and third portions.

[0015] The first connecting member may include one or more protrusions, e.g., fins, spines, or other structures suitable for increasing the surface area to volume ratio of the first connecting member. The second connecting member may include one or more protrusions, e.g., fins, spines, or other structures suitable for increasing the surface area to volume ratio of the second connecting member. Such protrusions of the first connecting member and / or the second connecting member may act to increase heat loss from the respective connecting member.

[0016] The circuit may include or take the form of a suitably programmed microcontroller. The current measurement may be based on a potential difference measured between the first connecting member and the second connecting member.

[0017] The first and third portions may be formed of different materials. The first and third portions may be formed of the same material. The first and third portions may be formed of a copper alloy.

[0018] The conductive elements may include or take the form of conductive traces, which may take the form of copper tracks supported on a substrate in the form of a printed circuit board (PCB).

[0019] The closest spacing between the first and second connecting members may be less than the spacing of the proximal ends of the first and second connecting members. The closest spacing may occur at respective points along the first and second connecting members. The closest spacing may occur along respective lengths of the first and second connecting members. The closest spacing may correspond to respective distal ends and / or respective lengths including the distal ends.

[0020] The nearest neighbor spacing may be 0.75 times or less the spacing between the proximal ends of the first and second connecting members. The nearest neighbor spacing may be 0.6 times or less the spacing between the proximal ends of the first and second connecting members. The nearest neighbor spacing may be 0.5 times or less the spacing between the proximal ends of the first and second connecting members. The nearest neighbor spacing may be 0.4 times or less the spacing between the proximal ends of the first and second connecting members. The nearest neighbor spacing may be 0.3 times or less the spacing between the proximal ends of the first and second connecting members. The nearest neighbor spacing may be 0.25 times or less the spacing between the proximal ends of the first and second connecting members.

[0021] A thermal bypass path having a bypass thermal conductance may couple a region of the first connecting member to a region of the second connecting member without passing through the second portion. A first thermal path having a first thermal conductance may extend between the thermal bypass path and a proximal end of the first connecting member through the first connecting member. A second thermal path having a second thermal conductance may extend between the thermal bypass path and a proximal end of the second connecting member through the second connecting member. The first thermal path, the second thermal path, and the thermal bypass path may be configured such that the thermal bypass path is electrically insulating, the bypass thermal conductance is greater than the first thermal conductance, and the bypass thermal conductance is greater than the second thermal conductance.

[0022] The thermal bypass path preferably corresponds to the closest spacing between the first and second connecting members. The thermal bypass path may connect regions that extend to the distal ends of the first and second connecting members. The thermal bypass path may connect regions that do not extend to the distal ends of the first and second connecting members.

[0023] The thermal bypass path may include heat flow through the substrate and / or the circuitry.

[0024] The substrate may take the form of a power electronics substrate or circuit board, for example a direct bond copper substrate, an active metal brazed substrate, an insulated metal substrate, etc. The circuitry configured to measure the voltage between the first and second connection members may be supported on the same substrate as the conductive elements. Alternatively, the circuitry configured to measure the voltage between the first and second connection members may be supported on a further substrate, for example a less expensive circuit board, mounted to (or having mounted on) the substrate.

[0025] The thermal bypass path may include heat flow through a thermal jumper mounted on the substrate to span the gap between the first and second connection members. The first and second connection members may be soldered, brazed, welded, or otherwise directly connected to metal terminals on either side of the thermal jumper. Additionally or alternatively, thermal grease, thermal compound (or similar products) may be applied to increase thermal conductance through the thermal jumper.

[0026] The apparatus may include a thermal jumper joined to span between distal ends of the first and second connecting members. The thermal jumper may be supported on a substrate. A distal end of each of the first and second connecting members may be sandwiched between the thermal jumper and the substrate.

[0027] The thermal jumper may include a first electrically conductive element and a second electrically conductive element electrically isolated from the first electrically conductive element. A distal end of the first connecting member may be electrically coupled to the first electrically conductive element. A distal end of the second connecting member may be electrically coupled to the second electrically conductive element. A circuit may be coupled between the first electrically conductive element and the second electrically conductive element of the thermal jumper.

[0028] The first portion may be joined to the second portion by a first weld and the second portion may be joined to the third portion by a second weld. A proximal end of the first connecting member may be as close to the first portion as possible without overlapping a weld area of ​​the first weld. A proximal end of the second connecting member may be as close to the third portion as possible without overlapping a weld area of ​​the second weld.

[0029] As used herein, a weld region in the context of a weld refers to any area of ​​a weld that has an observable difference in one or more of the following: material composition, grain size and / or grain orientation, precipitate size, density and / or composition, phase fraction, as compared to the respective bulk material within that area.

[0030] The second part is a mixture of 0 to 10×10 at temperatures ranging from 20°C to 50°C. -6 K -1 or 0~-10×10 -6 K -1 The second portion may include or take the form of a material having a temperature coefficient of electrical resistance of 0 to 20×10 at a temperature in the range of 20° C. to 50° C. -6 K -1 or 0~-20×10 -6 K -1 The electrical resistance may include or take the form of a material having a temperature coefficient of electrical resistance of .gtoreq..gtoreq..times ...

[0031] The second portion may include or take the form of a metal alloy including copper, nickel, and manganese. The metal alloy may take the form of Manganin®. The second portion may be formed of a metal alloy including copper, manganese, and optionally tin. The second portion may be formed of a metal alloy including nickel, chromium, and optionally aluminum. The second portion may be formed of a metal alloy including copper and zinc. The second portion may be formed of a metal alloy including copper and nickel. The second portion may be formed of a metal alloy including iron, chromium, and aluminum. The second portion may be formed of a metal alloy including aluminum, magnesium, and optionally chromium.

[0032] The body of the second portion may have a length along the first direction between the first portion and the third portion, a width along the second direction, and a thickness along the third direction. The first connecting member and the second connecting member may have a thickness along the third direction that is less than the thickness of the body.

[0033] The thickness of a first connecting member may mean, for a point along a first path, a dimension parallel to a third direction in a plane perpendicular to the first path at that point. The thickness of a second connecting member may mean, for a point along a second path, a dimension parallel to a third direction in a plane perpendicular to the second path at that point. The thickness of a first connecting member / second connecting member may mean the maximum thickness at any point along the first path / second path.

[0034] The thickness of the first and second connecting members may be 0.75 times the thickness of the body. The thickness of the first and second connecting members may be 0.6 times the thickness of the body. The thickness of the first and second connecting members may be 0.5 times the thickness of the body. The thickness of the first and second connecting members may be 0.4 times the thickness of the body. The thickness of the first and second connecting members may be 0.3 times the thickness of the body. The thickness of the first and second connecting members may be 0.2 times the thickness of the body. The thickness of the first and second connecting members may be 0.1 times the thickness of the body.

[0035] The body, first connecting member and second connecting member may be formed from a single piece of material by compressively deforming a portion of the single piece of material to form a region of reduced thickness, forming the body of the second portion from an undeformed portion of the single piece of material, and forming the first connecting member and second connecting member from the region of reduced thickness.

[0036] The body, the first connecting member, and the second connecting member may be formed from a single piece of material. The body, the first connecting member, and the second connecting member may be formed from a single piece of material by shearing. Shearing may include or take the form of a stamping process, a die cutting process, a fine blanking process, and the like. Alternatively, the body, the first connecting member, and the second connecting member may be formed from a single piece of material by any suitable process, including, but not limited to, etching, laser cutting, mechanical milling, spark erosion (electrical discharge machining).

[0037] A single piece of material may preferably be pre-connected to the first and / or third portion, for example strips or rolls providing the first, second and third portion material may be welded together and then separated (e.g. by shearing) to form a blank for further processing into a busbar connector.

[0038] The first connecting member and the second connecting member may each include or take the form of at least one section angled relative to the body. The at least one angled section may be at an angle of between 90° and 10° relative to the body. The at least one angled section may be at an angle of between 70° and 30° relative to the body. The first connecting member may take the form of a single straight section between the proximal and distal ends. The second connecting member may take the form of a single straight section between the proximal and distal ends. The first connecting member and the second connecting member may be angled relative to the body such that their respective distal ends are closer to each other than their respective proximal ends.

[0039] The first connecting member and the second connecting member may each include or be in the form of at least one curved section.

[0040] The first connecting member and the second connecting member may each have a serpentine configuration.

[0041] The busbar connector may be U-shaped. The busbar connector may be straight.

[0042] The body of the second portion may have a length along the first direction between the first portion and the third portion, a width along the second direction, and a thickness along the third direction. The extensions of the first and second connecting members from the body may have components parallel to the second direction. The first and third portions may have a maximum width along the second direction, the maximum width being sufficiently large such that neither the first nor the second connecting members protrude beyond the width of the first and third portions.

[0043] When the busbar is projected onto a plane perpendicular to the third direction (parallel to the thickness), neither the first nor the second connecting members can extend beyond the width of the first and third portions. In this manner, the extended widths of the first and third portions provide physical protection to the more delicate first and second connecting members during manufacturing, handling, and / or assembly processes.

[0044] The first and third portions may include a respective full-width section separate from the second portion and a respective reduced-width section coupled to the second portion. Each reduced-width section may be flush with a corresponding full-width section on one side of the respective first and / or third portion. In other words, the reduced-width section may be formed by a cutout from one side (parallel to the first direction) of the first and / or third portion. Alternatively, the reduced-width section may not be flush with the full-width section on one side of the first and / or third portion. In other words, the reduced-width section may be formed by a cutout from both sides (parallel to the first direction) of the first and / or third portion.

[0045] A transition between the reduced width section and the full width section of the first portion and / or the third portion may have a step profile. A transition between the reduced width section and the full width section of the first portion and / or the third portion may have an angled profile. A transition between the reduced width section and the full width section of the first portion and / or the third portion may have a curved profile.

[0046] The full width section of the first portion and / or the second portion may include a protrusion extending in a first direction and separated from the reduced width section by a gap in a second direction. The protrusion of the full width section is not coupled to the second portion and is configured to minimize current density through the protrusion when current flows between the first portion and the third portion. The protrusion of the first portion and / or the second portion may include a through hole used to mechanically secure the bus bar connector to a substrate.

[0047] The length of the reduced width section of each of the first and third portions along the first direction may be configured to minimize sensitivity change of the current sensor with temperature.

[0048] The length of the decay section that minimizes the change in sensitivity of the current sensor with temperature may be determined by increasing the length of the decay section until the percent change in sensitivity over the temperature range of 280K to 340K is less than or equal to a threshold sensitivity change. The threshold sensitivity change may be 0.05%. The threshold sensitivity change may be 0.04%. The threshold sensitivity change may be 0.03%. The threshold sensitivity change may be 0.02%. The threshold sensitivity change may be 0.01%.

[0049] Sensitivity is expressed in units of potential difference (Volts V) per unit current (Amps A) passing through the busbar connector. Determining the length of the attenuation section that minimizes the change in sensitivity of the current sensor with temperature may be determined by extrapolating or interpolating experimental results obtained using attenuation sections of various lengths. Preferably, determining the length of the attenuation section that minimizes the change in sensitivity of the current sensor with temperature may be determined using finite element analysis (FEA) modeling of the current flow in the busbar connector.

[0050] The first portion may include one or more through holes used to mechanically secure the bus bar connector to the substrate. Additionally or alternatively, the third portion may include one or more through holes used to mechanically secure the bus bar connector to the substrate. The size and location of any through holes may be configured to minimize sensitivity changes of the current sensor with temperature.

[0051] If the percent change in sensitivity over the temperature range of 280K to 340K is less than or equal to the threshold sensitivity change, then the size and location of the through-holes may be considered to minimize the sensitivity change.

[0052] The substrate (and / or further substrate supporting the substrate) may be coupled to the busbar connector using one or more through holes. If the first and second portions include a full width section including a protrusion, the through hole for connecting to the substrate (and / or further substrate supporting the substrate) may be arranged in the protrusion.

[0053] The apparatus may also include one or more temperature sensors. The circuitry may be configured to perform a temperature dependent sensitivity correction to the measured current based on the temperature measured by the one or more temperature sensors. The temperature dependent sensitivity correction may be implemented by firmware, for example, when the circuitry is in the form of a microcontroller or the like.

[0054] The one or more temperature sensors may include a first temperature sensor configured to measure a temperature of the first portion. The one or more temperature sensors may include a second temperature sensor configured to measure a temperature of the second portion. The first temperature sensor and / or the second temperature sensor may include or take the form of a thermocouple. The first temperature sensor and / or the second temperature sensor may include or take the form of a thermistor.

[0055] As an alternative, instead of circuits implementing the temperature dependent sensitivity corrections, these may be implemented by a controller of a DC electric meter that contains or is connected to the device.

[0056] The apparatus may also include one or more additional busbar connectors. Each additional busbar connector may be electrically connected in parallel with the busbar connector and may include a first portion, a second portion, and a third portion. A material forming the second portion may have a lower temperature coefficient of electrical resistance than a material forming each of the first portion and the third portion. The second portion of each additional busbar connector may include a body having the same dimensions as the body of the busbar connector.

[0057] In this manner, the total current capacity of the DC current sensor may be increased, or the sensitivity of the DC current sensor may be increased by increasing the resistance of the second portion without decreasing the total current capacity of the DC current sensor.

[0058] The first portion of the busbar connector and the first portion of the further busbar connector may be provided by a single piece folded back onto itself. Additionally and / or alternatively, the second portion of the busbar connector and the second portion of the further busbar connector may be provided by a single piece folded back onto itself.

[0059] One or more additional bus bar connectors may be stacked in parallel with the bus bar connector.

[0060] A second portion of at least one of the one or more additional busbar connectors may be integrally formed with the respective body and may include first and second connecting members configured similarly to the first and second connecting members of the busbar connector. All of the one or more additional busbar connectors may include first and second connecting members configured similarly to the first and second connecting members of the busbar connector.

[0061] The maximum current carrying capacity of the busbar connector may be at least 20 amps. The maximum current carrying capacity of the busbar connector may be at least 50 amps. The maximum current carrying capacity of the busbar connector may be at least 100 amps. The maximum current carrying capacity of the busbar connector may be at least 200 amps. The maximum current carrying capacity of the busbar connector may be at least 600 amps. The maximum current carrying capacity of the busbar connector may be at least 1000 amps.

[0062] The current sensor may be included in a DC electric meter. The DC electric meter may also include one or more additional current sensors, each additional current sensor being the same as the current sensor. The DC electric meter may also include a controller connected to the current sensor and each additional current sensor and configured to record a respective energy consumption corresponding to each current sensor.

[0063] The controller and one or more current sensors may be supported in a single package providing a DC electric meter. As used herein, the term "single package" may mean a single case or the like.

[0064] The DC electric meter may be connected to the current sensor, and the apparatus may further include one or more additional current sensors. Each additional current sensor may be the same as the current sensor. The DC electric meter may be connected to the current sensor and each of the one or more additional current sensors via respective wired or wireless links. The DC electric meter may be configured to record a respective energy consumption corresponding to each current sensor.

[0065] The DC electric meter may be a separate device from the current sensor and / or the one or more further current sensors. Each current sensor and / or the one or more further current sensors may take the form of a single device / single package. Additionally or alternatively, two or more current sensors may be packaged as a single device separate from the DC electric meter.

[0066] According to a second aspect of the invention, there is provided an assembly including a first portion, a second portion and a third portion. The material forming the second portion has a lower temperature coefficient of electrical resistance than the materials forming the first portion and the third portion, respectively. The second portion includes a body integrally formed with a first connecting member and a second connecting member. Each connecting member has a proximal end mated with the body and a distal end. The connecting members are configured such that when a first temperature difference exists between the respective proximal ends of the first connecting member and the second connecting member, a second temperature difference between the respective distal ends is less than or equal to 50% of the first temperature difference.

[0067] The assembly may take the form of a bus bar connector.

[0068] The assembly of the second aspect may include features corresponding to any features of the busbar connector included in the current sensor included in the apparatus according to the first aspect. Definitions (or features thereof) applicable to the busbar connector included in the current sensor of the first aspect may be equally applicable to the assembly of the second aspect.

[0069] The closest spacing between the first and second connecting members may be less than the spacing of the proximal ends of the first and second connecting members. The closest spacing may occur at respective points along the first and second connecting members. The closest spacing may occur along the length of each of the first and second connecting members. The closest spacing may correspond to the distal ends of each of the first and second connecting members.

[0070] The nearest neighbor spacing may be 0.75 times or less the spacing between the proximal ends of the first and second connecting members. The nearest neighbor spacing may be 0.6 times or less the spacing between the proximal ends of the first and second connecting members. The nearest neighbor spacing may be 0.5 times or less the spacing between the proximal ends of the first and second connecting members. The nearest neighbor spacing may be 0.4 times or less the spacing between the proximal ends of the first and second connecting members. The nearest neighbor spacing may be 0.3 times or less the spacing between the proximal ends of the first and second connecting members. The nearest neighbor spacing may be 0.25 times or less the spacing between the proximal ends of the first and second connecting members.

[0071] The first connecting member may extend along a first path between the proximal end and the distal end. The first path may have a first length. A first width of the first connecting member at each point along the first path may be a maximum dimension of the first connecting member perpendicular to the first path at that point. The first length may be three times or more than a maximum of the first width along the first path. The second connecting member may extend along a second path between the proximal end and the distal end. The second path may have a second length. A second width of the second connecting member at each point along the second path may be a maximum dimension of the second connecting member perpendicular to the second path at that point. The second length may be three times or more than a maximum of the second width along the second path.

[0072] The first path may be straight. The first path may be curved. The first path may include one or more angles. The first path may be serpentine. The second path may be straight. The second path may be curved. The second path may include one or more angles. The second path may be serpentine.

[0073] The first / second length may be 6 times or more than the maximum width of the first / second connection member perpendicular to the first / second path. The first / second length may be 6 times or more than the maximum width of the first / second connection member perpendicular to the first / second path. The first / second length may be 7 times or more than the maximum width of the first / second connection member perpendicular to the first / second path. The first / second length may be 8 times or more than the maximum width of the first / second connection member perpendicular to the first / second path. The first / second length may be 9 times or more than the maximum width of the first / second connection member perpendicular to the first / second path. The first / second length may be 10 times or more than the maximum width of the first / second connection member perpendicular to the first / second path.

[0074] According to a third aspect of the invention there is provided a use of an apparatus according to the first aspect for recording energy consumption corresponding to one or more loads.

[0075] According to a fourth aspect of the invention, there is provided a method of manufacturing a busbar connector. The method includes receiving a feedstock material including or in the form of a first region connected to a third region via a second region. The material forming the second region has a temperature coefficient of electrical resistance less than the temperature coefficient of electrical resistance of the materials forming the first and third regions, respectively. The method also includes removing material from the feedstock material to fabricate a busbar connector including a first portion formed from the first region, a second portion formed from the second region and including a body integrally formed with a first connecting member and a second connecting member, each connecting member having a proximal end mating with the body and a distal end projecting from the body, and a third portion formed from the third region. The first connecting member and the second connecting member are configured such that when a first temperature difference exists between the respective proximal ends of the first connecting member and the second connecting member, a second temperature difference between the respective distal ends is less than or equal to 50% of the first temperature difference.

[0076] The method of the fourth aspect may include features corresponding to any features of the busbar connector included in the current sensor included in the apparatus according to the first aspect. Definitions (or features thereof) applicable to the busbar connector included in the current sensor of the first aspect may be equally applicable to the method of the fourth aspect.

[0077] The first connecting member may extend along a first path between the proximal end and the distal end. The first path may have a first length. A first width of the first connecting member at each point along the first path may be a maximum dimension of the first connecting member perpendicular to the first path at that point. The first length may be three times or more than a maximum of the first width along the first path. The second connecting member may extend along a second path between the proximal end and the distal end. The second path may have a second length. A second width of the second connecting member at each point along the second path may be a maximum dimension of the second connecting member perpendicular to the second path at that point. The second length may be three times or more than a maximum of the second width along the second path.

[0078] Material may be removed from the feedstock by a shearing process, which may include or take the form of one or more of stamping, die cutting, and fine blanking.

[0079] Additionally and / or alternatively, material may be removed from the blank by one or more of a laser cutting process, a mechanical milling process, and a spark erosion (electrical discharge machining) process.

[0080] Removing material from the feedstock to produce the second portion may include compressively deforming a portion of the second region to form a reduced thickness region, forming a body of the second portion from the single piece, undeformed portion, and forming the first connecting member and the second connecting member from the reduced thickness region.

[0081] The first region may be welded to the second region, and the second region may be welded to the third region.

[0082] Removing material from the feedstock to fabricate the bus bar connector may include or be performed at a series of stations, where each station may remove material from the feedstock to form one or more features of the bus bar connector.

[0083] The feedstock may be in the form of a roll.

[0084] It is an object of the present disclosure to provide a meter with a shunt (second part) either integrated within the meter or remote to the meter.

[0085] According to a fifth aspect of the present invention, there is provided an energy meter including an input for receiving an output from a current sensor including a current shunt. The current shunt includes or is at least partially formed of a material having a low rate of change of resistivity with respect to temperature. The current shunt also includes legs (connecting members) formed as part of the shunt and made of a material having a low rate of change of resistivity with respect to temperature. The legs have a length or shape and / or cross-section that provides thermal resistance.

[0086] The PCB may be electrically connected to two legs (connecting members). The distance between the two legs (connecting members) on the PCB may be less than 6mm, or less than 4mm, or less than 1mm.

[0087] The legs (connecting members) may be configured to provide a thermal resistance between the shunt and the PCB. The legs (connecting members) may be thinner than the parent material to provide the thermal resistance. The legs (connecting members) may be less than 1 mm thick. Additionally or alternatively, the ratio of total thickness T to press thickness PT may be, for example, 2.5 mm / 0.75 mm. The legs (connecting members) may be less than 1.6 mm thick. The legs (connecting members) may be less than 2.5 mm wide. The legs (connecting members) may be less than 1.6 mm wide. The legs may be more than 2 mm long, and may be more than 4 mm long. The legs (connecting members) may have a ratio of legs separated by dimension x at the shunt and dimension y at the PCB, where y / x is less than 1, less than 0.75, or less than 0.5. The PCB end legs (connectors) can be electrically isolated and thermally shorted using FR4 PCB and / or copper track layers, or thermal jumpers, or thermal tape.

[0088] The energy meter may include a current sensor. A current modulator or chopper (circuit) may be mounted directly on the PCB (Printed Circuit Board).

[0089] The PCB design should preferably be such that the differential signal paths are (thermally) symmetrical, so that all potential EMFs are cancelled. This may require one or more of the following: · The symmetrical track (conductive elements) layout for the positive and negative signals (those provided to the current modulator (or other type of circuit)) may include some protection devices to protect the modulator from surge currents through the shunt, for example using series resistors. Additionally, anti-aliasing capacitors may be incorporated. The effects of thermal EMFs generated by all these devices and their connections may be reduced by the symmetry and by the short distances between the components. Symmetrical use of large ground islands under the circuit. ·The addition of thermally conductive material installed over the circuit to reduce temperature differences caused by convection currents in the air.

[0090] The resulting error may simply be due to a temperature difference between two connection points (electrically conductive elements) of the PCB. The connection lug can be extended to increase the thermal impedance of the connection lug. To minimize the temperature difference here, an isothermal block (thermal jumper) may be connected across the connection point. This block (thermal jumper) must be thermally shorted to the lug, but does not need to be electrically connected to it.

[0091] Insulated Metal Substrate (IMS) PCB technology may be used, which may provide electrical contact with a thin (usually around 100 μm) insulating layer and may provide an isothermal island for placing circuitry. This may reduce the number of separate components in the design, which may result in reduced cost and assembly time. The use of IMS technology may allow avoiding the limited connection area available for connection lugs.

[0092] Typically, the limiting factor in a successful isothermal connection is the insulating layer between the two tabs, and the size of the tabs is relatively small. IMS boards may have electrically large copper planes to spread the heat flow across the insulating layer. The thermal resistance of the isothermal block (and insulating layer) may be significantly less than that of the Manganin tab (connecting member). The tab may be of an appropriate length, for example, due to the relatively high thermal resistance of Manganin.

[0093] The connection tab (connection member) may be 3 mm long and 1×1 mm cross section. -1 The connection tabs soldered onto the IMS have a thermal impedance of 10K.W through the insulating layer. -1 Less than 0.01KW with aluminum base plate -1The IMS may have a thermal resistance of less than 100 μm thick insulation layer and a 1.6 mm thick aluminum layer. This may reduce the temperature difference at the material interface by a factor of 10 or more.

[0094] The connection between the shunt and the PCB may use lugs in the major plane of the busbar and / or bosses perpendicular to the major plane of the busbar. The shunt lugs may be thermally connected at or near the PCB using thermal jumpers.

[0095] Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0096] [Figure 1] 1 shows a prior art current sensor including a first prior art busbar. [Diagram 2] 2 shows a second prior art busbar; [Diagram 3] A and B show a third prior art busbar. [Figure 4] 4 shows a schematic temperature distribution in a second prior art busbar. [Diagram 5] 1 is an equivalent circuit for current sensor measurement. [Figure 6] Plot the results of a simulation of an electric meter compliance test. [Figure 7] FIG. 2 is a schematic plan view of a current sensor for a DC electric meter. [Figure 8] 8 is a simplified thermal equivalent circuit of a portion of the current sensor shown in FIG. 7. [Figure 9] 1 shows a first exemplary configuration of a connection member for a current bus bar. [Figure 10] 4 shows a second exemplary configuration of the connection members of the current bus bars. [Figure 11] 13 shows a third exemplary configuration of the connection members of the current bus bars. [Figure 12] 4 shows a fourth exemplary configuration of the connection members of the current bus bars. [Figure 13] 1 is a schematic plan view of a portion of an improved current sensor for a DC electric meter; [Figure 14] FIG. 4 is a schematic plan view of the second bus bar connector. [Figure 15] Plotting the calculated contours of potential V for the second busbar connector example. [Figure 16] Plotting the calculated contours of potential V for the second busbar connector example. [Figure 17] Plotting the calculated contours of current density j for the second busbar connector example. [Figure 18] Plotting the calculated contours of current density j for the second busbar connector example. [Figure 19] The modeled sensitivity change for the examples shown in Figures 17 and 18 is plotted versus current. [Figure 20] Modeled temperature is plotted versus current for the examples shown in FIGS. [Figure 21] 4 plots the calculated contours of current density j for a further example of a second busbar connector; [Figure 22] 22 is a graph comparing sensitivity change plotted against temperature for the examples shown in FIGS. 17 and 21. [Diagram 23] 4 plots the calculated contours of current density j for a further example of a second busbar connector; [Figure 24] 24 is a graph comparing sensitivity change plotted against temperature for the examples shown in FIGS. 17 and 23. [Diagram 25] 4 plots the calculated contours of current density j for a further example of a second busbar connector; [Figure 26] 26 is a graph comparing sensitivity change plotted against temperature for the examples shown in FIGS. 17, 23 and 25. [Figure 27A] 4 plots the calculated contours of current density j for further examples of second busbar connectors having progressively longer cutouts. [Figure 27B] 4 plots the calculated contours of current density j for further examples of second busbar connectors having progressively longer cutouts. [Figure 27C] 4 plots the calculated contours of current density j for further examples of second busbar connectors having progressively longer cutouts. [Figure 28] 27B is a graph comparing sensitivity change plotted against temperature for the examples shown in FIGS. 17, 27A, 27B and 27C. [Figure 29] 4 plots the calculated contours of current density j for a further example of a second busbar connector; [Diagram 30] For the example shown in FIG. 29, the change in sensitivity with respect to temperature is plotted. [Diagram 31] FIG. 13 is a schematic projection view of a third bus bar connector. [Diagram 32] AC show intermediate steps in fabricating a third busbar connector. [Diagram 33] 1A and 1B are schematic projection views of a first through-hole mounting method. [Diagram 34] 1A is a schematic plan view of the second through-hole mounting method, FIG. 1B is a side view, and FIG. [Diagram 35] 1A is a schematic plan view of a fifth bus bar connector, FIG. 1B is a side view, and FIG. [Diagram 36] 1A is a schematic plan view of a sixth bus bar connector, FIG. 1B is a side view, and FIG. [Figure 37] A is a schematic plan view of the net for the first laminated busbar connector, B is a schematic plan view of the first laminated busbar connector, C is a schematic side view along the width direction, D is a schematic side view along the length direction, and E is a schematic projection view. [Figure 38] A is a schematic plan view of a net for a second laminated busbar connector, B is a schematic plan view of the second laminated busbar connector, C is a schematic side view along the width direction, D is a schematic side view along the length direction, and E is a schematic projection view. [Figure 39] A is a schematic plan view of a net for a third laminated busbar connector, B is a schematic plan view of the third laminated busbar connector, C is a schematic side view along the width direction, D is a schematic side view along the length direction, and E is a schematic projection view. [Diagram 40] 1A is a schematic plan view of a fourth laminated bus bar connector, FIG. 1B is a schematic side view along the width direction, and FIG. 1C is a schematic projection view. [Diagram 41] 13A is a schematic plan view of the fifth laminated bus bar connector, B is a schematic side view along the width direction, and C is a pair of schematic projection views, one with a substrate and one without the substrate. [Diagram 42] FIG. 1 is a schematic block diagram of a DC electric meter. [Diagram 43] 5A to 5D show schematic diagrams of a method for manufacturing a bus bar connector. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0097] The present invention is based on the insight that a connector used to measure potential differences across a measurement area of ​​a current shunt used in a DC electric meter can be configured to reduce its sensitivity to temperature differences that may persist across the current shunt during use.

[0098] In the following, like parts are represented by like reference numerals.

[0099] A typical prior art configuration requires running a series of wires from a connection tab on the shunt of the current busbar to a remote set of electronics. This includes multiple sets of thermocouple junctions (2x shunt to wire, 2x wire to measurement electronics, PCB tracks to the components (further explained in conjunction with FIG. 5)). The above arrangement may, under practical circumstances, result in an offset voltage that appears in series with the shunt measurement voltage (further explained in conjunction with FIG. 5) and thus reduces measurement accuracy, especially at the lower end of the current measurement range.

[0100] For example: I max =200A (maximum rated current), I tr =3A(transition current) 100μΩ shunt - ANSI C12.32 meter with Class D accuracy.

[0101] Current busbar shunts are often made from Manganin® due to its stable resistance over temperature (<20 ppm / K) and low thermal EMF compared to copper. This material produces a power dissipation of 4 W in the shunt (which can cause a temperature rise of up to 40 K). The transition current I tr To maintain 0.2% accuracy, the offset voltage must be less than 600nV.

[0102] Isabellenhutte has estimated the thermal EMF of Manganin® against copper to be 1μV.K. -1 Therefore, for the thermal EMF to not (by itself) exceed the error budget, the two manganin-to-copper junctions must be within 0.6 K.

[0103] In real-world situations, additional challenges may be encountered.

[0104] The thermal environment of a current busbar may not be symmetrical. As an example, if one side of the busbar is connected to a cable of a suitable size (which generates little heat), but there is a DC contactor right next to it, the additional resistance and heat generated by the contactor will cause heat flow along the busbar. This may result in temperature differences between the sample points (as explained further in relation to Figure 4). This situation can also occur if one side of the meter is connected to a common busbar, and therefore the common busbar has different thermal properties than the single connecting cable, resulting in a temperature difference. This can also occur if one side of the meter is connected close to an in-line fuse, which dissipates heat by resistance during normal operation at rated current. Meter qualification testing includes a requirement to measure a maximum current (which generates heat in the shunt) followed by a minimum current (which is susceptible to offsets) in succession (as discussed further in relation to Figure 6).

[0105] To date, the following methods have been proposed to address these issues: Increasing the resistance of the shunt so that the offset voltage is small compared to the requirements, but this will mean a significantly increased heat dissipation, making the shunt physically larger and more expensive. ·Manganin® wire is used for the connections to the shunt. In theory this should mean that there are no dissimilar junctions in the area of ​​heat generation and thermal gradients. However, the Manganin® wire must be connected to the shunt, which can introduce other uncertainties. For example, the Manganin® wire may be of a different grade than the Manganin® in the shunt (processed differently than the sheet material, which may result in a different Seebeck coefficient). Small changes in material composition can have a large effect on the Seebeck coefficient.

[0106] The proposed examples do not use wires, which ensures that the exact location of the conductors can be controlled. Furthermore, the examples described herein do not require the use of welding to attach the busbars to the sensing circuitry. Instead, the substrate (such as a PCB) may be soldered using screen-printed solder, or the connection may be made by an alternative soldering process.

[0107] Referring to FIG. 1, a prior art current sensor is shown.

[0108] The prior art current sensor includes a first prior art busbar 1001 for transferring DC current to a load. The first prior art busbar 1001 includes a first prior art shunt 1002 connecting between a first copper bar 1003a and a second copper bar 1003b. The first prior art shunt 1002 is typically made from an alloy having a relatively high resistivity and a relatively low temperature coefficient of electrical resistance compared to the first copper bar 1003a and the second copper bar 1003b. For example, a copper manganese nickel alloy such as Manganin® (typically about 84.2% copper, about 12.1% manganese, and the remainder nickel), or other resistive alloys. The shunt 1002 is often made from Manganin® due to its stable resistance over temperature at typical operating temperatures (<20 ppm / K) and its low thermal EMF relative to typical conductors such as copper.

[0109] current I load passes through the first prior art busbar 1001, a potential difference ΔV appears across the first prior art shunt 1002.

number

number

[0110] Measuring the complete potential difference ΔV is difficult to achieve without interference due to contact resistance at the junction (usually welding) between the first copper bar 1003a and the second copper bar 1003b and the first prior art shunt 1002. Therefore, in many cases, the first wire 1004a and the second wire 1004b are connected to the first prior art shunt 1002 at a distance δx < L, for example, by welding, soldering, brazing, etc., and in an ideal situation, can be used to probe the potential difference δV. [Number] The other ends of the first wire 1004a and the second wire 1004b are respectively connected to, for example, soldered to the first conductive trace 1005a and the second conductive trace 1005b supported on the PCB 1006. The sensor module 1007 is connected via the first conductive trace and the second conductive traces 1005a, 1005b. For example, in the form of a microcontroller, microchip, field programmable gate array, application specific integrated circuit, etc. The sensor module 1007 is configured to sense the potential difference δV and the current I passing through the first prior art bus bar 1001 load so that it can be inferred. From which the current I load can be inferred. By combining with the measurement of the voltage V load applied to the load, the power and energy supplied to the load can be calculated.

[0111] In practice, additional thermoelectric emf may be generated between the first prior art shunt 1002 and the wires 1004a, 1004b, and / or between the wires 1004a, 1004b and the conductive traces 1005a, 1005b.

[0112] To avoid thermal EMFs at the wire shunt junctions, it has been proposed to use wires 1004a, 1004b having the same material composition as the first prior art shunt 1002 (see, for example, WO2014 / 093714A1). However, plate and wire stocks of the same supposed composition may not be identical and may still generate thermal EMFs. Even if the composition were identical, differences in microstructure due to wire extrusions, heat affected zones of weld joints, etc. may generate undesirable thermal EMFs.

[0113] For example, in American National Standards Institute Class D, ANSI C12.32 meters have a maximum load current of I load =I max =200A, transition current I tr = 3A, and a 100 μOhm shunt 1002. This material produces a power dissipation of 4 W in the shunt 1002. Such a power dissipation can cause a temperature rise of up to 40 K. The transition current I tr To maintain an accuracy of 0.2% at 1000 V, the offset voltage from the thermal EMF, i.e., the error in the potential difference δV, must be less than 600 nV. Assuming that the wires 1004a and 1004b are made of Manganin, and the Seebeck coefficient of Manganin with respect to copper is 1 μV.K, -1 So, for the thermal EMF to not exceed the error budget, the two Manganins need to be within 0.6 K of the copper junctions (between wires 1004a, 1004b and conductive traces 1005a, 1005b), which is discussed further below in relation to Figures 4 and 5.

[0114] Referring also to FIG. 2, a second prior art busbar 1002 is shown.

[0115] The second prior art busbar 1008 is substantially similar to the first prior art busbar 1001, except that a second prior art shunt 1009 is used instead of the first prior art shunt 1002. Instead of using wires 1004a, 1004b to connect to the conductive traces 1005a, 1005b (not shown in FIG. 2 for simplicity), a first protrusion 1010a and a second protrusion 1010b may extend from the second prior art shunt 1009 and be connected (e.g., soldered) to the conductive traces 1005a, 1005b. The first protrusion 1010a and the second protrusion 1010b are center-to-center a distance δx apart and each have a width w (parallel to the x-axis as shown) and a length l (parallel to the y-axis as shown), defining a relatively low aspect ratio, e.g., l / w≦2.

[0116] The unity of the first protrusion 1010a and the second protrusion 1010b may eliminate the pair of thermal EMFs. However, the inventors have realized that the relatively high thermal conductance of the first protrusion 1010a and the second protrusion 1010b may cause a temperature difference to be transferred to the connection of the first protrusion 1010a and the second protrusion 1010b with the respective conductive traces 1005a, 1005b. In effect, this simply transfers the thermal EMF problem to the connection to the conductive traces 1005a, 1005b. This will be explained in more detail in relation to Figures 4 and 5.

[0117] 3A and 3B, there is shown a third prior art busbar 1011. Figure 3A shows a plan view and Figure 3B shows a cross-sectional view along the line labeled A-A' in Figure 3A.

[0118] The third prior art busbar 1011 is substantially similar to the second prior art busbar 1008, except that the second prior art shunt 1009 is replaced with a third prior art shunt 1012 which is identical except for first and second protrusions 1010a, 1010b which extend parallel to the thickness direction (parallel to the z-axis as shown).

[0119] Although the first protrusion 1010a and the second protrusion 1010b in Figure 3B are shown extending from the entire thickness of the third prior art shunt 1012, this may vary depending on the formation mechanism used. For example, if the first protrusion 1010a and the second protrusion 1010b are punched out by a partial shearing process, the underlying third prior art shunt 1012 will deform (e.g., become hollow) due to the displacement of the material forming the first protrusion 1010a and the second protrusion 1010b.

[0120] Referring also to FIG. 4, a source of unwanted thermal EMF is shown in connection with a second prior art busbar 1008.

[0121] Load current I load When the second prior art busbar 1009 is supplied with a junction temperature, Joule heat is generated in the busbar 1009. The resistance R of the copper bars 1003a and 1003b is Cu is the resistance R of the second prior art shunt 1009 (due to the high resistivity of the material). shunt If the environmental and boundary conditions of the copper bars 1003a, 1003b are the same, the temperatures of the protrusions 1010a, 1010b will be symmetrical and the thermal EMFs at the connections to the respective conductive traces 1005a, 1005b will also be symmetrical and will cancel each other out.

[0122] However, in reality, the environmental and boundary conditions of the copper bars 1003a, 1003b are not the same. For example, one side will have a higher temperature if it is connected to an external power cable and the other to an internal connection. Additionally or alternatively, the contact resistances between the copper bars 1003a, 1003b and other connections (power cables, DC contactors, etc.) are generally not the same, which also leads to asymmetric heat fluxes.

[0123] Due to the asymmetry of the environment and boundary conditions of the copper bars 1003a and 1003b, a temperature profile 1013 as schematically shown in FIG. 4 may occur (note that the relative magnitude of the heating of the shunt 1009 is greatly exaggerated for visualization). As a result, a first temperature difference δT1 may be maintained between the ends of the protrusions 1010a and 1010b connected to the second prior art shunt 1009. The low aspect ratio and high thermal conductivity of the protrusions 1010a and 1010b mean that a second temperature difference δT2 between the free ends of the protrusions 1010a and 1010b is substantially the same as the first temperature difference

Number

[0124] Referring also to FIG. 5, equivalent circuit diagrams related to the prior art bus bars 1001, 1008, 10011 and the present invention are shown.

[0125] There is a thermal EMF 1、2 between the first copper bar 1003a and the shunts 1002, 1009, 1012, and there is another thermal EMF 2、3 between the shunts 1002, 1009, 1012 and the second copper bar 1003b. However, the EMF 1,2 and the EMF 2,3 are outside the measurement range, and no error occurs even with the first temperature difference δT1. The measurement of the potential difference δV is performed across the resistance between the wires 1004a, 1004b or the protrusions 1010a, 1010b, and is represented by R shunt to indicate that it is smaller than the total shunt resistance R * shunt where (assuming δx < L).

[0126] The EMF 1,a is generated at the junction between the shunts 1002, 1009, 1012 and the first wire 1004a or the first protrusion 1010a. The EMF 1,a may be negligible in the case of the first protrusion 1010a. The EMF 1,boccurs at the junction between the first wire 1004a or first protrusion 1010a and the first conductive trace 1005a.

[0127] Similarly, the EMF at the junction between the shunt 1002, 1009, 1012 and the second wire 1004b or the second prong 1010b 2,a In the case of the second protrusion 1010b, the EMF 2,a may be negligible. EMF 2,b occurs at the junction between the second wire 1004b or the second protrusion 1010b and the second conductive trace 1005b.

[0128] Next, the sensor module 1007 detects ΔV+EMF 1,a +EMF 1,b -EMF 2,b -EMF 2,a is measured so that the thermal EMF is cancelled when there is no temperature asymmetry along the x-axis. In practice, this situation does not generally occur, and a first error component ERR1=EMF 1,a -EMF 2,a and the second error component ERR2=EMF, which changes depending on the magnitude of the second temperature difference ΔT2. 1,b -EMF 2,b As described herein, the use of the protrusions 1010a, 1010b may minimize (to a negligible extent) the first error component ERR1. However, the inventors recognize that due to the high thermal conductance of the protrusions 1010a, 1010b, the second error component ERR2 may remain large enough to affect current sensing accuracy.

[0129] As an example, for a second prior art busbar 1008 with a Manganin® second prior art shunt 1009, and parameters w=3.8 mm, l=3.6 mm, t=2.5 mm, δx=22 mm (considered to be standard values), assuming the PCB 1006 was a PCB with two top 35 μm copper layers separated by a 0.1 mm thick layer of fiberglass (FR4), the second temperature difference would be

number

[0130] Referring also to FIG. 6, the effect of the unbalanced thermal EMF error ERR2 on the current sensor is shown.

[0131] Meter qualification tests include a maximum current I load =I max This current generates heat in busbars 1001, 1008, and 1011, and mainly in shunts 1002, 1009, and 1012, and then shortly thereafter a minimum current I load =I min The temperature differences δT1 and δT2 cause measurement errors, but these errors are limited to the maximum rated current I max Although it is relatively small, the minimum current required for measurement I min It becomes larger relative to

[0132] The plot shown in Figure 6 is the logarithmic current I load With the axis, I load Starting from 0.1A, gradually increase to I load =200A, then I load =0.1A. Error bars represent Class C (0.5%) maximum permissible error (MPE) bars in accordance with American National Standards Institute standard ANSI C12.32, valid as of December 2021. The circle at the beginning and arrow at the end of each series indicate the direction of the sweep. The first profile 1014 (dashed line) corresponds to a 75 μOhm busbar 1008, simulating a material with a thermal EMF coefficient of 0.6 μV / K relative to copper for conductive traces 1005a, 1005b, with a first temperature difference of δT1=1.25°C,

number

[0133] It can be observed that the first profile 1014 exceeds the desired error range for low currents when the first temperature difference δT1 is present, whereas if the second temperature difference δT2 could be relatively reduced when the first temperature difference δT1 is present, the error could be reduced to an acceptable level.

[0134] This specification outlines approaches that the inventors have discovered, alone or in combination, to reduce errors when there is a temperature difference between measurement locations on a current busbar that contains a shunt for measuring current.

[0135] Improved current sensors for DC electric meters. The current sensor according to the invention is configured to minimize the thermal EMF error that occurs. Wires 1004a, 1004a are not used. Instead, the inventors realized that the temperature difference between the ends could be more easily reduced by making the prongs 1010 significantly longer and thinner. The longer and thinner prongs could be wired to terminate closer together so that the thermal conductance between the ends could be more easily increased or even thermally "short-circuited" using a thermal jumper. Other improvements will be apparent from the description of the embodiments below.

[0136] Referring also to FIG. 7, a current sensor 1 for a DC electric meter is shown.

[0137] The current sensor 1 may be integrated into a DC electric meter 62 (FIG. 42), i.e., the DC electric meter 62 (FIG. 42) and the current sensor 1 are in a single package. Alternatively, the DC electric meter may be separate from the current sensor 1 and coupled to the current sensor 1 via one or more wired or wireless links (not shown in FIG. 7).

[0138] The current sensor 1 includes a busbar connector 2 in the form of a first portion 3 connected via a second portion 5 (or "shunt") to a third portion 4. The temperature coefficient of electrical resistance of the material forming the second portion 5 is less than the temperature coefficient of electrical resistance of the materials forming the first portion 3 and the third portion 4, respectively. For example, the second portion 5 may be formed of a material having a temperature coefficient of electrical resistance of: 0~10×10 -6 K -1 or 0~-10×10 -6 K -1 ,or 0~20×10 -6 K -1 or 0~-20×10 -6 K -1 The temperature range is 20° C. to 50° C. Suitable materials for the second portion 2 include metal alloys containing copper, nickel, and manganese, such as Manganin (registered trademark).

[0139] The second portion 5 includes a body 6 integrally formed with the first and second connection members 7a, 7b. The body 6 may be integrally formed with the first and second connection members 7a, 7b, for example, by cutting, etching, stamping, or milling from a single region of material (see also FIG. 43 for manufacturing methods). Each connection member 7a, 7b has a respective proximal end 8a, 8b that joins with the body 6, and a distal end 9a, 9b. Each of the distal ends 9a, 9b is electrically coupled to a respective conductive element 10a, 10b supported on a substrate 11, and coupled to a circuit 12 configured to measure a voltage δV between the first and second connection members 7a, 7b. In the example shown in FIG. 7, the conductive elements 10a, 10b take the form of conductive copper traces (copper electrical traces on a thin insulating layer on a thermally conductive metal layer) supported on a thermally conductive PCB substrate 11, although in general any conductive elements 10a, 10b and substrate 11 capable of providing a mechanically stable connection to the circuit 12 may be used.

[0140] The current carrying capacity of the busbar 2 is typically, but not limited to, 20 amps to 200 amps or more. For example, the maximum current carrying capacity of the busbar connector 2 may be at least 20 amps, preferably at least 50 amps, and more preferably at least 100 amps. The current carrying capacity of the busbar connector 2 may be 200 amps or more. In some cases, the current carrying capacity of the busbar connector 2 may be 600 amps or more. In some cases, the current carrying capacity of the busbar connector 2 may be 1000 amps or more.

[0141] The current sensor 1, in particular the first and second connection members 7a and 7b and their connections to the conductive elements 10a, 10b supported on the substrate 11, are configured such that when a first temperature difference δT1 exists between the proximal ends 8a, 8b of the first and second connection members 7a and 7b, the second temperature difference δT2 between the respective distal ends 9a, 9b is less than or equal to 50% of the first temperature difference δT1. Preferably, the second temperature difference δT2 is the smallest possible percentage of the first temperature difference δT1, ideally less than 10-20%. In other words, the distal ends 9a, 9b are configured to be as isothermal as possible.

[0142] As mentioned above, the first temperature difference δT1 may result from various sources, such as, for example, Joule heating in the busbar connector 2 (particularly the second part / shunt 5), heat flux between the first part 3 and / or the third part 4 and the external environment and / or connected parts.

[0143] One component that contributes to making the second temperature difference δT2 smaller compared to the first temperature difference δT1 is that the connecting members 7a, 7b are made elongated (high aspect ratio). Specifically, the first connecting member 7a extends along a first path 13a between the proximal end 8a and the distal end 9a.

[0144] The first path 13a has a first length s1, and at each point along the first path 13a, the first width w1 of the first connecting member 7a is the maximum vertical dimension of the first connecting member 7a at that point. By configuring the total length s1 to be three times or more the maximum value max(w1) of the first width w1 occurring along the first path 13a, an elongated and high aspect ratio is achieved even for a complex and non-linear path 13a. Similarly, the second connecting member 7b extends along the second path 13b between the proximal end 8b and the distal end 9b and has a second length s2. At each point along the second path 13b, the second width w2 of the second connecting member 7b is the maximum vertical dimension of the second connecting member 7b at that point. The second connecting member 7b is configured such that the second length s2 is three times or more the maximum value max(w2) of the second width w2 occurring along the second path 13b. As shown in the figure, the first connection member 7a, the second connection member 7b, and the main body 6 are arranged such that the center line of the main body 6 (where the current I load It is preferable that the flow rate is mirror-imaged (symmetrical) around the center (almost perpendicular to the flow of the water).

[0145] Due to the elongated nature of the connection members 7a, 7b, the distal ends 9a, 9b of the first and second connection members 7a, 7b are more thermally isolated from the proximal ends 8a, 8b (due to the higher thermal resistance along the paths 13a, 13b). Considering the thermal conductance between the first and second connection members 7a, 7b through the substrate 11, this allows the distal ends 9a, 9b to be closer to isothermal with each other. Referring again to FIG. 5, this results in a corresponding EMF at the interface between the first and second connection members 7a, 7b and the respective conductive elements 10a, 10b, the EMF 1、b , EMF 2、b As a result, the asymmetry between the current I load The error is reduced.

[0146] The extensions of the first and second members 7A, 7B also result in relatively increased surface heat losses along the first and second paths 13a, 13b, such that even in the absence of thermal conduction through the substrate 11, the temperatures of the distal ends 9a, 9b approach equilibrium with the ambient temperature (and thus with each other).

[0147] The extension of the connection members 7a, 7b does not introduce any significant IR error due to the high electrical impedance of the circuit 12 and the relatively small voltage difference ΔV, i.e., the current I flowing along the connection members 7a, 7b is negligible.

[0148] In general, the first and second paths 13a, 13b may be straight or curved, or may include more complex shapes that are a combination of two or more straight / curved sections (see Figures 9 to 12 for some non-exhaustive examples). In the example shown in Figure 7, the first and second paths 13a, 13b are shaped such that the distance between the distal ends 9a, 9b (parallel to the x-axis as shown) is shorter than the distance δx between the proximal ends 8a, 8b (the length used to measure δV). Specifically, each of the first and second paths 13a, 13b in the example of Figure 7 includes a straight section extending parallel to the y-axis from the body 6 as shown, connects at a 90° bend to a straight section extending parallel to the x-axis as shown, and then connects at a second 90° bend to a final straight section extending parallel to the y-axis from the body 6 as shown, terminating at the respective distal ends 9a, 9b.

[0149] The circuit 12 may be a suitably programmed microcontroller, a field programmable gate array, an application specific integrated circuit or the like, which controls the current I passing through the busbar connector 2 based on the potential difference δV between the first connection member 7a and the second connection member 7b. loadThe circuitry 12 may include or take the form of a similar circuit 12 configured to infer the potential difference δV. In some examples, the circuitry 12 may all be localized and supported on the substrate 11, as shown in FIG. 7. Alternatively, the circuitry 12 may be distributed, with only the elements necessary to measure the potential difference δV supported directly on the substrate 11. An example of a suitable circuit is described in WO2020 / 157477A1, and shown, for example, in FIG. 1 and / or FIG. 6 therein.

[0150] The DC electric meter 62 (FIG. 42) may be attached to the grounded portion of the load being monitored / measured. For example, one end of the bus bar connector 2 may be connected to ground, i.e., zero volt potential. Alternatively, the DC electric meter 62 (FIG. 42) may be connected to the high voltage side of the load being monitored / measured, which may be 200 VDC, 600 VDC, 1,000 VDC, 1,500 VDC, or higher. The DC electric meter 62 (FIG. 42) further measures the voltage difference, which is converted into the current I as described herein. load Combined with the measured value to calculate the power. The voltage V across the load being monitored / measured. load The measurement of is not substantially modified herein and the details thereof will not be described extensively for the sake of brevity.

[0151] The first portion 3 and the third portion 4 may be made of different materials, but are preferably made of the same material. The materials for the first portion 3 and the third portion 4 should have electrical conductivity as a priority, for example a copper alloy, which is known for its use as an electrical conductor.

[0152] Equivalent thermal circuit Viewed from another perspective of the invention, the first connecting member 7a and the second connecting member 7b, in combination with the substrate 11, are configured such that the thermal conductance between the distal ends 9a, 9b (not through the body 6) is equal to or preferably higher than the thermal conductance between each distal end 9a, 9b and the respective proximal end 8a, 8b. In this way, the first temperature difference δT1 may be maintained by heat generation in the body 6 and / or heat flux to / from the first and third parts 3 and 4, while the associated second temperature difference δT2 is reduced to a relatively greater extent.

[0153] Referring also to FIG. 8, a thermal equivalent circuit of the relevant parts of the current sensor 1 is shown.

[0154] The thermal resistances of the first portion 3, the second portion 5, and the third portion 4 are R θpart1 , R θpart2 , and R θpart3 and the heat flux J part1 , J part3 , and Joule heat (mainly the main body 6(I load ) 2 R shunt (but is not limited to) together with these (in the ideal case) determine the first temperature difference ΔT1.

[0155] For the purposes of this discussion, we will ignore surface losses from the connecting members 7a, 7b (and note that such surface losses only reduce the second temperature difference δT2) and define the thermal resistance between the proximal end 8a and the distal end 9a of the first connecting member 7a as R θconnect1 and the thermal resistance between the proximal end 8b and the distal end 9b of the second connecting member 7b is represented as R θconnect2 The thermal resistance between the distal ends of the connection members 7a, 7b via the conductive elements 10a, 10b and the substrate 11 is expressed as R θsub Then, the second temperature difference can be approximated as the product of a constant thermal reduction factor TRF and the first temperature difference ΔT1.

number

[0156] Thermal resistance R through the substrate 11 θsub can be reduced by a relatively small amount by increasing the contact area between the connecting members 7a, 7b and the conductive elements 10a, 10b and / or by enlarging the area of ​​the conductive elements 10a, 10b. The effect of the insulation and its thickness tends to dominate and is not easily controllable.

[0157] Finally, the thermal resistance R through the substrate 11 θsub The thermal resistance R along either of the connecting members 7a, 7b θconnect1 =R θconnect2 The ratio to can also be easily controlled by lengthening and / or reducing the cross-sectional area of ​​the connecting members 7a, 7b (ie, by giving them a long and narrow shape as shown herein).

[0158] Thermal jumper By shortening the path length through the substrate 11, it is also easy to couple the thermal jumper 14 between the first connection member 7a and the second connection member 7b. The thermal jumper 14 reduces the thermal resistance R θsub In parallel with the "short" thermal resistance R θshort and typically provides a thermal resistance R θsubIt may be an order of magnitude lower than that.

[0159] The thermal jumper 14 is an electrically insulating yet highly thermally conductive component, e.g., a block of aluminum nitride or equivalent material. The thermal jumper 14 typically (but not necessarily) has end regions metallized to allow connection to circuit elements (in this case conductive elements 10a, 10b) by soldering, brazing, welding, etc., which may help minimize contact thermal resistance. Additionally or alternatively, thermal grease, thermal compound (or similar product) may be applied to enhance thermal conductivity between the connecting members 7a, 7b through the thermal jumper 14.

[0160] Thermal resistance R of thermal jumper 14 θshort The small size and finite size of the thermal resistance R θconnect1 , R θconnect2 This means that only a portion of R is not shorted by the thermal jumper 14. For example, as shown in FIG. θconnect1 Part of R θ1a The proximal end 8a is connected to the beginning of the thermal jumper 14, and is also connected to the second connecting member 7b. Then, the net thermal resistance is dominated by the thermal jumper 14, i.e., the thermal resistance R θshort is the residual thermal resistance R through the substrate 11. θ1b , R θ2b , and thermal resistance R θsub is connected in parallel with the sum of

[0161] Thermal resistance R θshort As long as the thermal jumper 14 is relatively small, it can be effective even if it is not located at or near the distal ends 9a, 9b. The thermal jumper 14 may be connected to any point along the first and second connecting members 7a, 7b.

[0162] In the general case, a thermal bypass path R 100 connecting the area of ​​the first connecting member 7 a to the area of ​​the second connecting member 7 b without passing through the second portion 5 is provided. θbypass can be approximated by

[0163] In the simplified thermal circuit of Figure 8, the thermal bypass path R θbypass is the thermal resistance R through the board 11 when the thermal jumper 14 is not present and when the thermal jumper 14 is included. θsub become.

number

[0164] First thermal resistance R θ1a The first heat path having the first connecting member 7a is connected to the heat bypass path R θbypass and the proximal end 8a of the first connecting member 7a. Similarly, a second thermal path having a second thermal resistance Rθ2a is 、 Thermal bypass path Rθbypass and second connecting member 7b The thermal bypass path R extends between the proximal end 8b of the thermal bypass tube 1 and the second connecting member 7b. θbypass are electrically isolated. Bypass thermal resistance R θbypass is the first thermal resistance R θ1a and the second thermal resistance R θ2a The second temperature difference ΔT2 can be approximated as:

number

[0165] In the example shown in FIG. 7, using a Manganin® second portion 5, with constant cross-sectional areas of connecting members 7a, 7b set at w1=w2=0.8 mm, t=0.5 mm, s1=s2=9 mm, and a spacing of 1.7 mm (center-to-center) between distal ends 9a, 9b, and assuming substrate 11 is a copper clad thermal PCB covered with 0.1 mm thick fiberglass, the second temperature difference is

number

number

[0166] Thermal jumper configuration If included, the thermal jumper 11 may be positioned relative to the connection members 7a, 7b and the substrate 11 in any manner that allows efficient thermal contact.

[0167] For example, the thermal jumper 14 may be disposed (on the same plane) between the first connection member 7a and the second connection member 7b as shown in FIG.

[0168] Alternatively, the distal ends 9a, 9b of the first connecting member 7a and the second connecting member 7b may be sandwiched (in the thickness direction z) between the thermal jumper 14 and the substrate 11. In other words, the thermal jumper 14 may be placed on the upper surfaces of the first connecting member 7a and the second connecting member 7b.

[0169] In another example, metallization of the ends of the thermal jumper 14 may provide conductive elements 10a, 10b to which the first and second connection members 7a, 7b are attached, and may further be coupled to conductive traces on the substrate 11. In other words, the thermal jumper 14 may be sandwiched (in the thickness direction z) between the first and second connection members 7a, 7b and the substrate 11.

[0170] Avoiding the weld-affected area Referring again to FIG. 7, in the busbar connector 2, the first portion 3 is typically joined to the second portion 5 by a first weld 15a, and the second portion 5 is typically joined to the third portion 4 by a second weld 15b. The width of the welds may be about 0.3 mm, or about 0.5 mm, or about 1 mm. If the welds 15a, 15b are not used, other processes involving increased temperature may occur. In any case, there will be an area on either side of the weld (or other joint) that is affected by the welding process. As used herein, the affected area, for example in relation to the welds 15a, 15b, refers to the area on either side of the welds 15a, 15b, within which there is a visible difference in one or more of material composition, porosity, inclusions, grain size and / or orientation, precipitate size and / or density, phase fraction relative to untreated Manganin® alloy, as compared to the respective bulk material.

[0171] The proximal end 8a of the first connection member 7a is preferably as close as possible to the first portion 3 so as not to overlap with the area affected by the first weld 15a. Similarly, the proximal end 8b of the second connection member 7a is preferably as close as possible to the third portion 4 so as not to overlap with the area affected by the second weld 15b. This allows δx / L to be maximized.

[0172] In general, the shape of the channels 13a, 13b of the connecting members 7a, 7b is not particularly limited.

[0173] First Configuration Example of Connection Member Referring also to FIG. 9, a first configuration example 16 of the connection members 7a, 7b is shown (hereinafter "first configuration").

[0174] A first configuration 16 may be used with the busbar connector 2 and is substantially identical to that shown in FIG. 7, except for the relative lengths of the straight portions.

[0175] Each of the first and second connecting members 7a, 7a (and associated paths 13a, 13b) includes a first straight section 17a, 17b extending parallel to the y-axis from the body 6 as shown, connects at a 90° bend to a second straight section 18a, 18b extending parallel to the x-axis as shown, and then connects at a second 90° bend to a third straight section 19a, 19b extending parallel to the y-axis from the body 6 as shown and terminating at a respective distal end 9a, 9b.

[0176] In the general case, the relative lengths of the first sections 17a, 17b, the second sections 18a, 18b, and the third sections 19a, 19b are such that the overall lengths s1, s2 have a sufficiently large thermal resistance R θ1a and R θ2a There is no need to be particularly limited as long as the above considerations for making it correspond to the above are observed.

[0177] Optionally, a thermal jumper 14 may be included in any of the relative positions described herein.

[0178] Second Configuration Example of Connection Member Referring also to FIG. 10, a second configuration example 20 of the connecting members 7a, 7b is shown (hereinafter "second configuration").

[0179] A second configuration 20 may be used with the busbar connector 2 and is the same as the first configuration 16, except that the second sections 18a, 18b are not at a 90° angle relative to the first sections 17a, 17b and the third sections 19a, 19b.

[0180] In a modification of the second configuration, the first section 17a, 17b and / or the third section 19a, 19b may be omitted. In other words, each connection member 7a, 7b may take the form of a single angled straight section between the proximal end 8a, 8b and the distal end 9a, 9b. The single straight section may form an angle of up to 90° with the edge of the body 6 from which it extends. An angle of less than 90° may be preferred to reduce the length of the thermal path through the substrate 11 and / or to facilitate thermally shorting the connection members 7a, 7b using the thermal jumper 14.

[0181] Optionally, a thermal jumper 14 may be included in any of the relative positions described herein.

[0182] Third Configuration Example of Connection Member Referring also to FIG. 11, a third configuration example 21 of the connection members 7a, 7b is shown (hereinafter, "third configuration").

[0183] A third configuration 21 may be used with the busbar connector 2 and is the same as the third configuration 20, except that instead of having clearly defined sections, each connection member 7a, 7b is formed with a single continuous S-shaped curve. Modifications to use other types of curves are not believed to affect the functionality described herein.

[0184] Optionally, a thermal jumper 14 may be included in any of the relative positions described herein.

[0185] Fourth Configuration Example of Connection Member Referring also to FIG. 12, a fourth configuration example 22 of the connection members 7a, 7b is shown (hereinafter, "fourth configuration").

[0186] A fourth configuration 21 may be used for the busbar connector 2 and is similar to the first to third configurations 16, 20, 21, except for the shape of the connecting members 7a, 7b. In the fourth configuration, each connecting member 7a, 7b has a serpentine configuration. While Figure 12 shows a serpentine configuration made up of multiple straight sections, in other examples the serpentine configuration may take the form of a single continuous curve (e.g., a sinusoidal curve).

[0187] The first to fourth configurations 16, 20, 21, 22 represent non-exhaustive examples, and many further specific configurations of the connecting members 7a, 7b are possible to reduce the relative magnitude of the second temperature difference δT2, which are also consistent with the principles described herein. For example, straight connecting members 7a, 7b extending at a 90° angle may be used in combination with a jumper 14 of sufficiently low thermal resistance.

[0188] Optionally, a thermal jumper 14 may be included in any of the relative positions described herein.

[0189] Thermal jumper in the middle of the connection As previously mentioned, if a thermal jumper 14 is included, it need not be disposed to couple between the distal ends 9a, 9b of the connecting members 7a, 7b.

[0190] For example, and referring also to FIG. 13, there is shown a portion of an improved current sensor 1b highlighting the coupling of connecting members 7a, 7b with conductive elements 10a, 10b.

[0191] The improved current sensor 1b implements a fourth serpentine configuration 22 type. The proximal ends 8a, 8b and distal ends 9a, 9b are equally spaced apart by a distance δx, but the loop segments 23a, 23b of each of the serpentine connecting members 7a, 7b are spaced apart by a distance δx along their respective paths 13a, 13b. min The thermal jumper 14 is disposed over and bonded to the loop segments 23a, 23b, forming a thermal bypass path R θbypass provide (or at least substantially control)

[0192] In this way, the distal ends 9a, 9b are substantially isolated from the first temperature difference δt1 while at the same time being widely spaced apart to provide more space for making connections to the respective conductive elements 10a, 10b.

[0193] Physical protection of connecting members As described herein, the connecting members 7a, 7b according to the present disclosure serve to reduce thermal EMF errors of the current sensor. However, the long and thin connecting members 7a, 7b used may be susceptible to inadvertent mechanical deformation during manufacturing, handling and / or installation of the current busbar connector 2.

[0194] Referring also to FIG. 14, a second bus bar connector 24 is shown.

[0195] The second bus bar connector 24 differs from the first bus bar connector 2 only in the shapes of the first portion 3 and the third portion 4.

[0196] As described above, the body 6 of the second portion 5 has a length L between the first portion 3 and the third portion 4 in a first direction (x-axis in the figure) and a width L in a second direction (y-axis in the figure). W1 , and a thickness t along a third direction (the z-axis out of the plane of the illustration). The first connecting member 7a and the second connecting member 7b extend in a direction away from the body 6 with a component parallel to the second direction (the y-axis as shown). The component parallel to the width W1 is denoted as E in FIG. y It is written as follows.

[0197] To protect the first and second connecting members 7a, 7b from inadvertent mechanical deformation, the first and third portions 3, 4 each have a maximum width W2 along the second direction (the y-axis as shown), which is large enough that neither the first and second connecting members 7a, 7b protrude beyond the width W2 of the first and third portions 3, 4. In other words, W1+E y ≦W2.

[0198] In this manner, the expanded width W2 of the first and third portions 3, 4 provides physical protection to the more delicate first and second connection members 7a, 7b during manufacturing, handling and / or assembly processes. In effect, the connection members 7a, 7b are defined within cutouts in the second busbar connector 24.

[0199] The first portion 3 and the third portion 4 each include a full-width section 25a, 25b separate from the second portion 5 and a reduced-width section 26a, 26b coupled to the second portion 5. The transition between the reduced-width section 26a, 26b and the full-width section 25a, 25b of the first portion 3 and / or the third portion 4 may have a gently curved profile 27a, 27b as shown in FIG.

[0200] Alternatively, the transition between the reduced width sections 26a, 26b and the full width sections 25a, 25b of the first portion 3 and / or third portion 4 may have a stepped profile, an angled profile, or the like.

[0201] 14 , the reduced width sections 26a, 26b may be flush with the full width sections 25a, 25a along a first side 28 of the first portion 3 and / or the third portion 4. In other words, the reduced width sections are cut out from an opposing second side 29 of the first portion 3 and / or the third portion 4.

[0202] Alternatively, the reduced width sections 26a, 26b need not be flush with the full width sections 25a, 25b of either side 28, 29 of the first portion 3 and / or third portion 4. In other words, the reduced width sections 26a, 26b may take the form of cut-outs from both side surfaces 28, 29 of the first portion 3 and / or third portion 4.

[0203] 15 and 16, calculated contours of electric potential V for an example second bus bar connector 24 are shown.

[0204] The contours of the electric potential V were calculated using Finite Element Analysis (FEA) calculations carried out using Comsol Multiphysics (version 5.6.0.341). The thermal conductivity of Manganin® forming the second portion 5 is 2 W.mK. -1 It was.

[0205] The examples of Figures 15 and 16 are both examples of the second configuration 20 in which the first section 17 and the third section 19 are omitted. In the example of Figure 15, the edge 30 of the main portion 6 between the connecting members 7a, 7b is not flush with the outer edges 31a, 31b of the main portion. In Figure 15, the offset is labeled δy. In contrast, in the example of Figure 16, the inner edge 30 is flush with the outer edges 31a, 31b of the main portion 6.

[0206] In each of Figures 15 and 16, the voltage contours extending through the connection members 7a, 7b are used as the endpoints of the distance δx. A first observation, which applies to both the busbar connector 2 and the second busbar connector 24, is that when edge 30 is offset from edges 31a, 31b (i.e., not flush), the voltage contours are distorted and the relative fraction δx / L is reduced. In the example of Figure 15

number

number

[0207] The second observation is specific to the second busbar connector 24. In the busbar connector 2, the current density j flowing into and out of the second portion 5 is approximately uniform due to the constant width W throughout the busbar connector 2. However, as can be observed from Figures 15 and 16, the transition between the full width sections 25a, 25b and the reduced width sections 26a, 26b results in a concentration of voltage contours (and therefore current density j) such that the current density j flowing into and out of the second portion 5 is not uniform.

[0208] The material of second portion 5 (usually Manganin) does not exhibit a large change in resistance with temperature, whereas the material of first portion 3 and third portion 4 (usually copper) does exhibit a large change in resistance with temperature. As a result, in addition to the current density j into and out of second portion 5 being non-uniform, the exact non-uniformity is expected to exhibit a temperature dependence.

[0209] One way to alleviate such problems is to include one or more temperature sensors 29 (FIG. 42) coupled to the circuit 12. One suitable type of temperature sensor is a thermocouple. For example, one temperature sensor 32 (FIG. 42) may be coupled to the first portion 3 and another temperature sensor 32 may be coupled to the second portion 4. The circuit then generates a measured current I based on the temperature measured by the temperature sensor 32 (FIG. 42). load It may be configured to perform a temperature dependent sensitivity correction for

[0210] In addition to or instead of implementing temperature dependent sensitivity compensation in the circuit 12, the shape and configuration of the first portion 3 and the third portion 4 may be optimized to promote uniformity of the current density, thereby minimizing the sensitivity change of the current sensor with temperature. Specifically, the reduced width sections 26a, 26b have a constant width W1 at a relative distance L confor the difference in width W2-W1. Other factors that may affect the temperature dependent sensitivity are discussed below. Sensitivity corresponds to units of potential difference (Volts V) per unit of current (Amps A) passing through the bus bar connector 24.

[0211] Referring also to Figures 17 and 18, there are shown the calculated contours of current density j for the example second busbar connector 24. Figure 18 is an enlarged region of Figure 17. The calculations were the same as in Figures 15 and 16, the only differences being the specific geometry of the parts 3, 4, 5 modelled and the output variable being current density j rather than voltage.

[0212] The example of Figures 17 / 18 is an example of a second busbar connector 24, in which the connection members 7a, 7b generally correspond to the second configuration 20 with the first sections 17a, 17b omitted.

[0213] Although not shown in the preceding examples for visual clarity, the busbar connectors 2, 24 may also include connection through-holes 33 used for electrical connection of the busbar connectors 2, 24, and mounting through-holes 34 used for mechanically fastening the busbar connectors 2, 24 to the substrate 11 and / or the current sensors 1, 1b and / or other structures of the electric meter containing the current sensors 1, 1b. The through-holes 33, 34 also affect the current density and therefore have been included in the simulations to aid in the discussion of temperature dependent sensitivity optimization.

[0214] In the example of Figure 17 / Figure 18, L con The ratio of / (W2-W1) is about 0.24, which indicates that the distance over which the current density regains uniformity is relatively short compared to the change in width.

[0215] Referring also to Figure 19, the modeled sensitivity evolution for the example in Figures 17 / 18 is shown for the current I load is plotted against

[0216] Referring also to FIG. 20, the temperature of the modeled second part 5 (shunt) of the example of FIG. 17 / FIG. 18 varies with the current I load is plotted against

[0217] The overall effect is a sensitivity change of the order of 0.15% between 270K and 350K. Two cases are plotted in Figs. 19 and 20, the first case (solid line) being a symmetrical thermal configuration with a heat sink coupled to both the first part 3 and the third part 4. The second case (dashed line) corresponds to an asymmetrical thermal configuration with a heat sink coupled to only one of the first part 3 and the third part 4. It can be observed that the temperature effect is more pronounced in the asymmetrical case. The asymmetrical case is more reflective of the actual arrangement of the DC electric meter 62 (Fig. 42) and the current sensors 1, 1b.

[0218] Referring also to Figure 21, there is shown the calculated contours of current density j for the example second busbar connector 24. The calculations were the same as in Figures 17 and 18, the only difference being the specific geometry of parts 3, 4, 5 that were modelled.

[0219] The example of Figure 21 is the same as the example of Figures 17 / 18, except that in addition to the cutout 35 from the second side 29 around the connecting members 7a, 7b, the example of Figure 21 also includes a second cutout 36 from the first side 28, the second cutout 36 having a length corresponding to the first cutout 35.

[0220] See also Figure 22, where the change in sensitivity is plotted against temperature for the example of Figures 17 / 18 (solid line - "original design") and the example of Figure 21 (dashed line - "notched"), where the temperature was assumed to be uniform in both cases.

[0221] In the example of Figure 21, it can be observed that the change in sensitivity with temperature is reduced with the inclusion of the second cutout 36. Without wishing to be bound by theory, it is speculated that the inclusion of the side cutouts 35, 36 increases the symmetry of distortion about the centerline of the body 6 (parallel to the x-axis as shown).

[0222] When implementing the second example bus bar connector 24, it may be preferable to include a second notch 36.

[0223] Referring also to Figure 23, there is shown the calculated contours of current density j for the example second busbar connector 24. The calculations were the same as in Figures 17 and 18, the only difference being the specific geometry of parts 3, 4, 5 that were modelled.

[0224] The example of FIG. 23 is the same as the example of FIG. 17 / FIG. 18, but the relative lengths of the reduced width portions 26a, 26b are increased to a ratio L con The difference is that / (W2-W1) has increased to approximately 0.91 (compared to 0.24 for the Fig. 17 / Fig. 18 examples). For visual clarity, the through holes have not been relabeled.

[0225] See also Figure 24, where the change in sensitivity is plotted against temperature for the example of Figures 17 / 18 (solid line - "original design") and the design of Figure 23 (dashed line - "original design, additional notch"), where the temperature was assumed to be uniform in both cases.

[0226] It can be seen that the sensitivity change in the example of Figure 23 is improved over the examples of Figures 17 / 18, but not as much as expected. Without wishing to be bound by theory, it is believed that the close correspondence of the mounting through holes 34 to the transition between the full width sections 25a, 25b and the reduced width sections 26a, 26b creates a distortion that causes the length L to evolve uniformly for the current density j before it reaches the second portion 5. con It is speculated that this is contrary to the increase in

[0227] Referring also to Figure 25, this concept was tested by simulating contours of current density j for an example identical to that of Figure 23, except that the mounting through-hole 34 closest to the second portion 25 has been omitted. Labels identical to those in Figure 23 have been omitted for visual clarity, and for the same reasons the through-holes 33, 34 are not labeled.

[0228] Referring also to Figure 26, the change in sensitivity is plotted against temperature for the example of Figures 17 / 18 (solid line - "original design"), the design of Figure 23 (dotted line - "original design, additional cutout"), and the example of Figure 25 (dashed line - "additional cutout, no hole"). In all cases the temperature was assumed to be uniform.

[0229] The example of Figure 25 was observed to have a smaller sensitivity change than the example of Figure 23, indicating that it is preferable to position the through holes 33, 34 away from the transitions between the full-width sections 25a, 25b and the reduced-width sections 26a, 26b of the first and third parts 3, 4.

[0230] 27A-27C to consider the effect of expansion on the example of FIG. 25 (omitting the mounting through-hole closest to second portion 5). FIG. 27A is a reproduction of FIG. 25 with added annotations. The example of FIG. 27B corresponds to the example of FIG. 25 where cutout 35 has been expanded by a further 4 mm. The example of FIG. 27C corresponds to the example of FIG. 25 where cutout 35 has been expanded by a further 8 mm. The calculations were the same as in FIGS. 17 and 18, the only difference being the specific shape of portions 3, 4, 5 that were modeled. For visual clarity, through-holes 33, 34 have not been labelled.

[0231] In the examples of Figures 27A, 27B, and 27C, the ratio L con / (W2-W1) was approximately 0.91, 1.23, and 1.56, respectively.

[0232] Referring also to Figure 28, the change in sensitivity versus temperature is plotted for the example of Figures 17 / 18 (solid line - "no expansion"), the design of Figures 25 / 27A (dashed line - "no expansion, with notch, no hole"), the example of Figure 27B (dotted line - "no expansion, with medium notch, no hole"), and the example of Figure 27C (dashed line - "no expansion, with large notch, no hole"). In all cases, the temperature was assumed to be uniform.

[0233] The example in FIG. conIt can be observed that with an increase in the ratio / (W2-W1), the sensitivity change is further reduced compared to the example of Figure 25 / Figure 27A. However, with further increases, as in the example of Figure 27C, the sign of the sensitivity change is reversed and the magnitude increases again. The exact reason for this behavior is unclear. It may be related to the transition between the full width sections 25a, 25b and the reduced width sections 26a, 26b that begin to approach the next set of through holes 34, or another factor that is not clear at this time.

[0234] From a practical standpoint, the simulations of FIGS. 27A-27C show that for a given busbar connector 24 geometry, the length of the attenuation sections 26a, 26b that minimizes the sensitivity change with temperature of the current sensor 1, 1b can be determined by gradually increasing the length of the attenuation sections 26a, 26b (ratio L) until the percent change in sensitivity over the temperature range of 280 K to 340 K is below the threshold sensitivity change. con / (W2-W1) (by increasing W2-W1). For example, the threshold sensitivity change can be 0.05%, although lower changes are achievable, as shown in the examples of Figures 27A and 27B.

[0235] Such optimization may be performed experimentally. Additionally or alternatively, the optimization may be performed using finite element analysis (FEA) modeling of the current flow within the bus bar connector 24, as described herein. Preferably, the optimization is performed using FEA modeling, followed by experimental validation and / or fine tuning.

[0236] Referring again to the example of Figure 27B, it can be observed that the sensitivity change associated with the full width portions 25a, 25b may be offset, however this is done by moving the transition between the full width sections 25a, 25b and the reduced width sections 26a, 26b sufficiently far away from the second portion 5 and the connecting members 7a, 7b, thereby sacrificing some of the originally intended mechanical protection.

[0237] Referring also to Figure 29, a modification of the example of Figure 27B is shown. The calculation of the current density j is the same as in Figures 17 and 18, the only difference being the specific shape of the modeled parts 3, 4, 5. For visual clarity, the through holes 33, 34 are not labelled.

[0238] In the example of FIG. 29, the full-width sections 25a, 25b of the first and second parts 3, 4, respectively, include projections 37a, 37b that extend into the cutouts 35 (parallel to the x-axis as shown) and are separated from the corresponding reduced-width sections 26a, 26b by gaps 38 (in the y-direction as shown). The projections 37a, 37b are not connected to the second part 5. In effect, the gaps 38 define slots and are spaced apart by a ratio L con / (W2-W1) can be maintained while allowing protrusions 37a, 37b to extend closer to connecting members 7a, 7b, providing mechanical protection against inadvertent deformation during manufacture, handling, and / or assembly.

[0239] Referring to FIG. 30, the change in sensitivity for the example of FIG. 29 (dashed line--'no magnification, notch, no hole') is plotted against temperature.

[0240] It can be observed that the sensitivity change of the example of FIG. 29 is nearly identical to that of the example of FIG. 27B shown in FIG.

[0241] Furthermore, the arrangement of the protrusions 37a and 37b is such that the current I load This is done so that the current density j flowing through the protrusions 37a, 37b is minimal (or zero) when the protrusions 37a, 37b pass between the first and third portions (the protrusions 37a, 37b are effectively "dead ends"). As a result, the protrusions 37a, 37b may provide suitable locations for mounting the through holes 34 that do not affect the current density j in the bus bar connector 24. For example, the bus bar connector 24 may be mechanically fixed to the substrate 11 (or directly).

[0242] Reduced thickness connection material As described herein, it is desirable to increase the thermal resistance of the first and second connecting members 7a, 7b. One way to do so is to decrease the widths w1, w2 and increase the lengths s1, s2 of the paths 13a, 13b. Thermal resistance is also increased by decreasing the thicknesses t1, t2 of the connecting members 7a, 7b, respectively, relative to the thickness t of the body 6. This is difficult to achieve while forming the first and second connecting members 7a, 7b integrally with the body 6. For example, welding a thinner plate to the body 6 and then cutting, stamping, etc. the shape of the connecting members 7a, 7b would result in the same problems as simply welding wires of conceptually the same composition. Specifically, conceptually identical compositions are often not identical in practice, and even slight changes in the proportions of compositional components or impurities may result in unacceptable thermal EMFs.

[0243] Referring also to Figure 31, there is shown an example of a third busbar connector 39. Referring also to Figures 32A to 32C, steps for manufacturing the third busbar connector 39 are shown.

[0244] The third busbar connector 39 is the same as the second busbar connector 24 (which may include any of the features described in connection therewith), except that the thicknesses t1, t2 (parallel to the z-axis as shown) of the connection members 7a, 7b are relatively thinner than the thickness t (parallel to the z-axis as shown) of the body 6. The third busbar connector 39 shown in Figures 31 and 32 includes cutouts 35, 36 from the first side 28 and the second side 29. Through holes 33, 34 are not shown for visual purposes, but may be included in an actual embodiment for electrical / mechanical connection purposes. As shown in Figure 31, the third busbar connector 39 is connected to conductive elements 10a, 10b supported on the substrate 11, with a thermal jumper 14 connected therebetween. The conductive elements 10a, 10b take the form of conductive traces that terminate at respective landing pads 40a, 40b for connection to the circuit 12.

[0245] 32A , the single piece of material 41 forming the body 6 and connecting members 7a, 7b is welded (or otherwise joined) between the first portion 3 and the third portion 4. The single piece of material 41 has a protrusion 42 that extends beyond the width W1 of the reduced width sections 26a, 26b of the first portion 3 and the third portion 4.

[0246] 32B, the projections 42 are compressively deformed to form areas of reduced thickness 43. The remaining undeformed portion of the single piece 41 forms the body 6.

[0247] 32C, the first connecting member 7a and the second connecting member 7b are formed by removing material from the reduced thickness region 43. Preferably, a shearing process is used, such as a stamping process, a die cutting process, a fine blanking process, etc. Alternatively, the first connecting member 7a and the second connecting member 7b may be formed by any suitable process, including, but not limited to, etching, laser cutting, mechanical milling, spark erosion (electrical discharge machining).

[0248] The thickness of the reduced thickness region 43, which defines the thicknesses t1, t2 of the connecting members 7a, 7b, can be controlled to any fraction of the thickness t of the body 6 by controlling the compressive deformation process (e.g., the stroke depth of a piston). For example, the thickness t=2.5 mm of the body 6 is reduced to t1=t2=0.75 mm, which is a fraction of 0.3.

[0249] In forming the region 43 of reduced thickness by compression, the microstructure of the material changes. First, the typical grain shape is compressed at a rate that is equivalent to the thickness t. Second, the extensive plastic processing increases the dislocation density in the region 43 of reduced thickness. The microstructural discontinuities may generate undesirable thermal EMFs. If undesirable thermal EMF generation does occur, it may be mitigated by compensation using one or more temperature sensors 32 (FIG. 42). Furthermore, residual stresses may remain after the forming process. Therefore, the third busbar connector 39 is preferably subjected to a heat treatment after fabrication. This type of heat treatment is called "artificial aging" and must be performed at a temperature high enough to activate dislocation motion so that residual stresses can be relieved and excess dislocation density can be reabsorbed. However, for practical reasons of avoiding excessive oxidation, the heat treatment is likely not high enough for grain boundary strengthening.

[0250] For second portion 5 formed of Manganin®, the heat treatment may take the form of one or more cycles from ambient temperature to about 100-140°C. Thermal oxides formed during aging may be removed by "pickling" with an acidic solution to destabilize the oxides. Additionally or alternatively, thermal oxidation may be mitigated or avoided by carrying out the heat treatment in a vacuum or in an inert atmosphere such as nitrogen, argon, etc.

[0251] There are two main constraints on how thin the thickness t1, t2 of the connecting members 7a, 7b can be: First, the connecting members 7a, 7b must be mechanically robust enough to be able to connect to the conductive elements 10a, 10b without inadvertent deformation. Second, in case of excessive deformation, artificial aging may not be sufficient to prevent the generation of unwanted thermal EMFs at the proximal ends 8a, 8b.

[0252] Through hole mounting on board In the previous examples, the connection members 7a, 7b were connected to the conductive elements 10a, 10b either by soldering, welding, brazing or similar methods. By fixing the substrate 11 to (or directly against) the first part 3 and / or the third part 4 using the mounting through holes 34, a more robust mechanical support is provided.

[0253] 33A and 33B, a first through-hole mounting method using a fourth bus bar connector 44 is shown.

[0254] With particular reference to FIG. 33A, the fourth bus bar connector 44 is a modification of the third bus bar connector 39 in which each of the connecting members 7a, 7b includes a 90° bent section 45a, 45b with corresponding distal ends 9a, 9b facing downward relative to the z-axis as shown.

[0255] 33B, a substrate 11 in the form of a PCB includes conductive elements 10a, 10b in the form of plated through holes 46a, 46b which receive the distal ends 9a, 9b of the connecting members 7a, 7b, respectively. The distal ends 9a, 9b may be retained within the plated through holes 46a, 46b by friction fit, but for a more secure connection are preferably retained by soldering, brazing or similar methods. The forward connection to the circuitry 12 may be supported on one or both sides of the PCB substrate 11, or through an internal conductive layer if the PCB is multi-layered.

[0256] 34A-34C, there is shown a second through-hole mounting method using a third bus bar connector 39. Fig. 34A is a plan view, Fig. 34B is a side view, and Fig. 34C is a projection view.

[0257] Similar to the first through hole mounting method shown in Figures 33A and 33B, the second through hole mounting method also utilized a substrate 11 including plated through holes 46a, 46b that receive distal ends 9a, 9b of the substrate 11. However, in the second through hole mounting method, the connection members 7a, 7b are not bent to include 90 degree bend sections 45a, 45b; instead, the substrate is oriented perpendicular to the bus bar connector 39. As shown in Figures 34A-34C, the substrate 11 is aligned in the xz plane with the thickness aligned with the y axis as shown.

[0258] Fifth Exemplary Bus Bar Connector 35A-35C, a fifth exemplary bus bar connector 47 (hereinafter, the "fifth bus bar connector") is shown.

[0259] FIG. 35A is a plan view of the fifth bus bar connector 47, FIG. 35B is a side view, and FIG. 35C is a projection view.

[0260] The fifth busbar connector 47 comprises a first portion 3 and a third portion 4 configured according to the example of Fig. 29, combining a cut-out 36 from the first side 28 with a thinning of the connecting members 7a, 7b as described for the fifth busbar connector 39. In this way, the fifth busbar connector 39 combines the aforementioned advantages of using elongated connecting members 7a, 7b to reduce the second temperature difference δT2, while mechanically protecting the connecting members 7a, 7b, as well as compensating for temperature dependent sensitivity changes resulting from the transition from the full width portions 25a, 25b to the reduced width sections 26a, 26b.

[0261] The fifth busbar connector 47 also includes mounting through holes 34 located within protrusions 37a, 37b from the full width portions 25a, 25b. The mounting through holes 34 are for mechanically securing the fifth busbar connector 47 to the substrate 11. As previously described, the location of the protrusions 37a, 37b minimizes (or avoids) sensitivity changes of the current sensors 1, 1b with temperature due to current density j concentration. The remaining mounting through holes 34 are also configured to minimize sensitivity changes by being located away from the transitions between the full width sections 25a, 25b and the reduced width sections 26a, 26b of the first and third portions 3, 4.

[0262] Sixth Exemplary Bus Bar Connector 36A-36C, a sixth exemplary bus bar connector 47 (hereinafter, the "sixth bus bar connector") is shown.

[0263] FIG. 36A is a plan view of the sixth bus bar connector 47, FIG. 36B is a side view, and FIG. 36C is a projection view.

[0264] The sixth bus bar connector 48 is the same as the fifth bus bar connector 47, except that the widths W1 and W2 are both relatively large, and the mounting through holes 34 on the outer sides of the projections 37a and 37b are omitted.

[0265] The sixth busbar connector 48 has a larger maximum current capacity I due to the increased width W 1 of the second portion 5 of the body 6, compared to the fifth busbar connector 47. max In general, the maximum current carrying capacity of busbar connectors is I max can be configured as required by enlarging the width W1 and / or thickness t of the body 6. This can be done without sacrificing the thermal insulation of the distal ends 9a, 9b of the connecting members 7a, 7b by using the thinning methods described in relation to Figures 31 to 32C.

[0266] Stacked Busbar Connectors In addition to or instead of increasing the width W1, adding more busbar connectors in parallel can increase the maximum current carrying capacity I max can be increased.

[0267] In general, the current sensor 1, 1b may include one or more further busbar connectors 49 (FIGS. 37A-37E). Each further busbar connector 49 is electrically connected in parallel with the busbar connector 2, 24, 39, 44, 47, 48 and includes a first portion 3b, a second portion 5b and a third portion 4b (FIGS. 37A-37E). The material forming the second portion 5b of each further busbar connector 49 must be the same as the material forming the second portion 5 of the busbar connector 2, 24, 39, 44, 47, 48. The second portion 5b of each further busbar connector 49 includes a body 6b having the same dimensions as the body 6 of the busbar connector 2, 24, 39, 44, 47, 48.

[0268] In this way, the total current capacity of the DC current sensor I max Alternatively, the resistance R of the second portion 5 used to measure the voltage drop ΔV may be increased. shunt By increasing the total current capacity I max The sensitivity of the DC current sensor 1, 1b can be increased without decreasing

[0269] First Stacked Busbar Connector 37A-37E, a first laminated bus bar connector 50 is shown.

[0270] FIG. 37A is a plan view of the net 51 folded to form the first laminated busbar connector 50, FIG. 37B is a plan view of the first laminated busbar connector 50, FIG. 37C is a side view along the width direction (y-axis as shown), FIG. 37D is a side view along the length direction (x-axis as shown), and FIG. 37E is a projection view.

[0271] As used herein, a "net" may also be referred to as a "flat pattern." A net or flat pattern is the shape of a sheet metal part before it is formed and may be used to create a drawing for manufacturing. The net / flat pattern preferably shows the bend lines, bend areas, punch locations, and the overall shape of the part with all bends flattened and bending factors taken into account.

[0272] The first laminated busbar connector 50 is formed by folding a net 51 about a fold line 52. The net 51 includes a fifth busbar connector 47 along a widthwise edge of the first portion 3 which is joined to a widthwise edge of a first portion 3b of another busbar connector 49 along the fold line 52. The structure of the fifth busbar connector 47 and the further busbar connector 49 are mirrored about the fold line 52, except that the second portion 5b of the further busbar connector 49 does not include the connection members 7a, 7b and the first portion 3b and the third portion 4b of the further busbar connector 49 do not include the protrusions 37a, 37b.

[0273] The reduced width sections 26a, 26b of the fifth busbar connector 47 and the corresponding reduced width sections (not specifically labelled) of the further busbar connector 49 are deformed into an S-shaped region 53, so that the second portions 5, 5b are offset in the same direction (parallel to the z-axis as shown) in the net 51 and in the opposite direction in the folded first laminated busbar connector 50. This may be advantageous as the more resistive second portions 5, 5b are kept apart in the first laminated busbar connector 50, where they can better dissipate Joule heat generated therein. The deformation of the sigmoidal shaped region 53 may be produced using a stamping process, and the particular deformation shape providing the offset should be, but is not limited to, the same in both the fifth busbar connector 47 and the further busbar connector 49. It is preferred that the second portions 5, 5b are protected from deformation.

[0274] The net 51 that is folded to form the first laminated busbar connector 50 may instead have a configuration in which the fifth busbar connector 47 is joined along the widthwise edge of the second part 4, along the fold line 5, to the widthwise edge of the second part 4b of the further busbar connector 49.

[0275] Second Stacked Busbar Connector Referring also to Figures 38A-38E, a second laminated bus bar connector 54 is shown.

[0276] FIG. 38A is a plan view of the net 55 (or "flat pattern") folded to form a second laminated busbar connector 54, FIG. 38B is a plan view of the second laminated busbar connector 54, FIG. 38C is a side view along the width direction (y-axis as shown), FIG. 38D is a side view along the length direction (x-axis as shown), and FIG. 38E is a projection view.

[0277] The second laminated busbar connector 54 is the same as the first laminated busbar connector 50, except that the net 55 that is folded to form the second laminated busbar connector 54 is folded about a fold line 56 that joins the fifth busbar connector 47 to the further busbar connector 49 along the first edge 28.

[0278] 3rd Stacked Busbar Connector 39A-39E, a third stacked bus bar connector 57 is shown.

[0279] FIG. 39A is a plan view of the net 55 (or "flat pattern") folded to form the third laminated bus bar connector 54, FIG. 39B is a plan view of the third laminated bus bar connector 54, FIG. 39C is a side view along the width direction (y-axis as shown), FIG. 39D is a side view along the length direction (x-axis as shown), and FIG. 39E is a projection view.

[0280] The third laminated busbar connector 57 is the same as the second laminated busbar connector 54, except that the thickness t of the main portions 6, 6b, the first portions 3, 3b, and the second portions 4, 4b is equal to the thickness t1=t2 of the connecting members 7a, 7b. This simplifies the manufacture and at the same time reduces the current carrying capacity I of the second portion 5 alone. maxが It will double.

[0281] 4th Stacked Busbar Connector 40A-40C, a fourth laminated bus bar connector 58 is shown.

[0282] FIG. 40A is a plan view, FIG. 40B is a side view along the width direction (the y-axis in the figure), and FIG. 40C is a projection view.

[0283] The fourth stacked busbar connector 58 includes the fifth busbar connector 47 stacked in parallel with a pair of further busbar connectors 49. Each further busbar connector 49 is identical to the fifth busbar connector 47 except that it omits the connecting members 7a, 7b and the protrusions 37a, 37b of the first and third parts 3, 4.

[0284] The busbar connectors 47, 49 are stacked along the thickness direction (z-axis as shown) and separated by washers 59. The washers 59 may be insulating, but do not allow the current I load The fifth busbar connector 47 is preferably electrically conductive to evenly distribute heat. The spacing provided by the washers 59 may help to dissipate heat generated in the second portions 5, 5b. The mounting through holes 34 on the prongs 37a, 37b of the fifth busbar connector 47 are used to mount the substrate 11 using bolts 60. The other through holes 33, 34 are in line with all of the busbar connectors 47, 49.

[0285] Although not formed from a single net 51, 55 (or flat pattern), the fourth stacked busbar connector 58 may be more easily extended to any number of further busbar connectors 49 (limited only by space constraints etc.). In general, the fourth stacked busbar connector 58 includes any number of further busbar connectors 49 stacked in parallel with the busbar connector 47, which may range from one to as many as will fit in the available space. In this way, the maximum current carrying capacity Imax may be extended while maintaining the sensitivity of the measurement of δV across the second portion 5 of the busbar connector 47 and the thermal isolation.

[0286] 5th Stacked Busbar Connector 41A-41C, a fifth laminated bus bar connector 61 is shown.

[0287] FIG. 41A is a plan view, FIG. 41B is a side view along the width direction (the y-axis in the figure), and FIG. 41C shows projections with and without substrates 11, 11b.

[0288] The fifth laminated busbar connector 61 is the same as the fourth laminated busbar connector 58, but each further busbar connector 49 is identical to the fifth busbar connector 47 except for omitting the protrusions 37a, 37b on the first and second parts 3, 4.

[0289] The connection members 7a, 7b of each further busbar connector 49 are coupled to a respective substrate 11b supporting the conductive elements 10a, 10b. In this way, the circuit 12 is connected to a current I passing through each second portion 5, 5b. load The portions 5, 5b may be measured independently. This may be more accurate than assuming that the current I flowing through each second portion 5, 5b is the same, particularly if there are a large number of further busbar connectors 49 (as is the case for the first to fourth stacked busbar connectors 50, 54, 57, 58). The substrates 11, 11b are preferably all identical.

[0290] In a modification, some (but not all) of the further busbar connectors 49 may include connection members 7a, 7b connected to the substrate 11b for monitoring with the circuit 12. For example, in a larger stack, every other busbar connector 47, 49 may be monitored to make current measurements.

[0291] In a modification, all of the further busbar connectors 49 may further include protrusions 37a, 37b.

[0292] Integrated DC Electric Meter Referring to FIG. 42, a DC electric meter 62 is shown.

[0293] The DC electric meter 62 includes the current sensor 1, 1b and a controller 63 connected to the circuit 12 of the current sensor 1, 1b by a link 64. The link 64 can be wired or wireless. Although FIG. 42 shows a seventh busbar connector 65 that generally corresponds to the fifth busbar connector 47, the current sensor 1, 1b may use any of the busbar connectors 2, 24, 39, 44, 47, 48 or the laminated busbar connectors 50, 54, 57, 58, 61 (or variations thereof).

[0294] The seventh busbar connector 65 differs from the fifth busbar connector 47 in that the free ends 66a, 66b of the first and third portions 3, 4 are each curved 90 degrees, resulting in the seventh busbar connector 65 being generally U-shaped in plan view. Any of the busbar connectors described herein may be modified to have the same U-shaped plan view shape as the seventh busbar connector 65.

[0295] Optionally, the DC electric meter 62 may further include one or more current sensors 1, 1b, each connected to a controller 63 via a wired or wireless link 64, respectively.

[0296] The DC electric meter 62 may be attached to a grounded portion of the load being monitored / metered. For example, one end of the bus bar connector 2 may be connected to ground, i.e., zero volt potential. Alternatively, the DC electric meter 62 may be connected to the high voltage side of the load being monitored / metered, which may be 200VDC, 600VDC, 1,000VDC, 1,500VDC, or higher. The DC electric meter 62 further measures the voltage difference, which is converted into a current I as described herein. load Combine with the measurements to calculate power.

[0297] The controller 63 is configured to record the respective energy consumption corresponding to each current sensor 1, 1b. The controller 63 may also record other information including, but not limited to, one or more of the total charge delivered through each current sensor 1, 1b and / or the energy charge consumption as a function of time. The controller 63 also records the voltage V across the load being monitored / measured, whether from the circuit 12 or from another sensor. load , which is used in the power and energy calculations. The controller 63 may take the form of a suitably programmed microcontroller, a field programmable gate array, an application specific integrated circuit, or other similar means.

[0298] The controller 63 and the one or more current sensors 1, 1b are preferably supported within a single package, such as a single case, that provides a DC electric meter 62.

[0299] Optionally, any or all of the current sensors 1, 1b may include one or more temperature sensors 32. The circuit 12 then monitors the temperature(s) and calculates the measured current I based on the measured temperature. loadAlternatively, the circuit 12 may simply report the temperature measurements to the controller 63, which performs the temperature dependent sensitivity correction. The temperature sensor 32 may be located anywhere in the first portion 3, the second portion 4, and / or the third portion 5, but in general it will be sufficient to have a first temperature sensor 32 configured to measure the temperature of the first portion 3 and a second temperature sensor 32 configured to measure the temperature of the second portion 4. The temperature sensor 32 may preferably be located near the second portion 5, since the area of ​​greatest importance is the interface with the second portion 5. The temperature sensor 32 may include or take the form of a thermistor or an isolated thermocouple.

[0300] Distributed DC Electric Meter In a modification of the DC electric meter 62 not shown, some or all of the current sensors 1, 1b may be packaged separately and installed separately from the DC electric meter (which still includes at least the controller 63). Each current sensor 1, 1b remains coupled to the DC electric meter 62 by a respective wired or wireless link 64.

[0301] This option may be useful to move the DC electric meter 62 and its controller 63 away from the seventh busbar connector 65, which may reduce electromagnetic interference. The distributed option may also be preferred when it is desired to monitor a large and / or widely spaced set of current sensors 1, 1b. For example, the current sensors 1, 1b may monitor the energy supplied to a set of electric vehicle charging points, which are necessarily spaced quite far apart.

[0302] Busbar connector manufacturing The bus bar connectors described herein may be manufactured using any known method.

[0303] An exemplary method will be described with reference to Figures 43A-43D.

[0304] Initially, a feedstock 67 is received that includes a first region 68 connected to a third region 69 via a second region 70. For example, the first region 68 may be welded to the second region 70, and the second region 70 may be welded to the third region 69.

[0305] In the diagram of Figure 43A the feedstock 67 is in the form of a roll 71, however, the feedstock 67 may alternatively be in the form of a flat strip or plate, or a pre-cut "blank" that already has a perimeter corresponding to the shape of the final busbar connector. The first region 68 will form one or more first portions 3, 3b, the second region 70 will form one or more second portions 5, 5b, and the third region 69 will form one or more third portions 4, 4b.

[0306] The busbar connector(s) 2, 24, 39, 44, 47, 48, 49 are then formed by removing material from the feedstock 67 to form the first portion 3, 3b and the third portion 4, 4b, and the body 6 and connecting members 7a, 7b of the second portion 5, 5b. The removal of material may be performed in one or more steps, for example at different stations in a production line. If the feedstock 67 is used to define multiple busbar connectors 2, 24, 39, 44, 47, 48, 49, it is necessary to separate the individual busbar connector(s) 2, 24, 39, 44, 47, 48, 49 at at least one station.

[0307] The same process may also be used to manufacture nets 51, 55 for folding into busbar connectors 50, 54, 57, and the production line may further include stations for deforming and folding the nets 51, 55 (or flat patterns). Depending on the layout of the nets 51, 55, modified feedstock 67 may be required. For example, the net 55 for folding into the second laminated busbar connector 54 may be manufactured using the feedstock of FIG. 43A, but the net 51 for folding into the first laminated busbar connector 50 would require modified feedstock.

[0308] Preferably, material is removed from the feedstock 67 by shear processes such as stamping, die cutting, and fine blanking. These techniques are particularly suited to high throughput and may be implemented as a roll-to-roll process using patterned rollers.

[0309] Additionally and / or alternatively, material may be removed from feedstock 67 by one or more of a laser cutting process, a mechanical milling process, and a spark erosion process, or any other suitable method for selective material removal.

[0310] If the method of thinning the connecting members 7a, 7b described in relation to Figures 31 to 32C is used, the production line will also include a station for compressing the protrusions 42 to form the reduced thickness areas 43.

[0311] Intermediate steps of an example four station process production line are also described with reference to Figures 43B-43D.

[0312] 43B in particular, the first stamping station receives stock material 67 in the form of a roll 71 or plate and punches through holes 33, 34 and notches 35, 36 to generally define the shape of the connected first and third portions 3, 4 along edges 28, 29 (formed upon cutting along border region 72), as well as the single piece of material 41 and corresponding protrusions 42. In Figures 43B-43D, border region 72 is shown in dashed lines, although in reality border region 72 has a finite width to account for material loss in the final step of separating the individual bus bar connectors 2, 24, 39, 44, 47, 48, 49.

[0313] Although not shown in FIG. 43B, the first stamping station (and / or subsequent stations) may stamp and / or punch one or more alignment marks (not shown) for use in alignment by subsequent processing stations.

[0314] With particular reference to FIG. 43C, a second stamping station compresses the projections 42 to form the reduced thickness regions 43 and the body 6.

[0315] With particular reference to FIG. 43D, a third stamping station stamps out excess material from reduced thickness region 43 leaving first connecting member 7a and second connecting member 7b.

[0316] Finally, in a fourth station, the individual busbar connectors 2, 24, 39, 44, 47, 48, 49 are sheared, punched, sawed or otherwise cut off by removing the border area 72. As already mentioned, in a practical process, the border area 72 has a finite width.

[0317] It will be apparent how a particular process is illustrated in Figures 43B-43D and may be modified and / or extended to produce any of the bus bar connectors 2, 24, 39, 44, 47, 48, 49 and / or nets 51, 54 (or variations thereof as described) described herein.

[0318] change It will be understood that various modifications may be made to the embodiments described above, including equivalent and other features already known in the design, manufacture, and use of energy meters and their component parts, and which may be used instead of or in addition to features already described herein. Features of one embodiment may be replaced or supplemented by features of another embodiment.

[0319] The first and / or second connecting members 7a, 7b may further include one or more protrusions, e.g., fins, spines, or other structures suitable for increasing the surface area to volume ratio. This may facilitate surface heat loss to the surroundings and help to further equalize the temperature between the distal ends 9a, 9b. If such protrusions are included, it may be difficult to evaluate the condition based on the ratio of the maximum widths max(w1), max(w2) to the path lengths s1, s2. However, such protrusions do not interfere with the condition expressed in terms of relative thermal resistance. Alternatively, protrusions / fins / spines etc. that have an apparently negligible effect on the thermal resistance between the proximal ends 8a, 8b and the distal ends 9a, 9b of the connecting members 7a, 7b may simply be ignored for the purposes of evaluating the maximum widths max(w1), max(w2).

[0320] Although the claims have been described in this application with respect to particular combinations of features, it will be understood that the scope of the present disclosure also includes any novel feature or any novel combination of features or any generalization thereof disclosed herein, either explicitly or implicitly, whether or not they relate to the same invention as currently claimed in any claim, and whether or not they alleviate any or all of the same technical problems that the present invention alleviates. The applicants hereby notify that new claims may be formulated to such features and / or combinations of such features during the prosecution of this application or any further application derived therefrom.

Claims

1. 1. An apparatus including a DC electric meter, the DC electric meter includes a current sensor; or the DC electric meter is connected to the current sensor; The current sensor a busbar connector including a first portion connected to a third portion via a second portion, wherein the second portion is made of a material having a temperature coefficient of electrical resistance that is less than the temperature coefficients of electrical resistance of materials forming the first portion and the third portion, respectively; the second portion includes a body integrally formed with a first connecting member and a second connecting member, each connecting member having a proximal end mating with the body and a distal end electrically coupled to a respective conductive element supported on a substrate and coupled to a circuit configured to measure a voltage between the first connecting member and the second connecting member; The device is configured such that when a first temperature difference exists between the respective proximal ends of the first connecting member and the second connecting member, a second temperature difference between the respective distal ends is less than or equal to 50% of the first temperature difference.

2. the first connecting member extends along a first path between the proximal end and the distal end, the first path having a first length, a first width of the first connecting member at each point along the first path being a maximum dimension of the first connecting member perpendicular to the first path at that point, and the first length being greater than or equal to three times the maximum first width along the first path; 2. The device of claim 1, wherein the second connecting member extends along a second path between the proximal end and the distal end, the second path having a second length, a second width of the second connecting member at each point along the second path being a maximum dimension of the second connecting member perpendicular to the second path at that point, and the second length is greater than or equal to three times the maximum second width along the second path.

3. The device of claim 1 , wherein the closest spacing between the first connecting member and the second connecting member is less than the spacing between the respective proximal ends of the first connecting member and the second connecting member.

4. a thermal bypass path having a bypass thermal conductance couples a region of the first connecting member to a region of the second connecting member without passing through the second portion; a first thermal path having a first thermal conductance extending through the first connecting member between the thermal bypass path and the proximal end of the first connecting member; a second thermal path having a second thermal conductance extending through the second connecting member between the thermal bypass path and the proximal end of the second connecting member; the thermal bypass path is electrically insulating; the bypass thermal conductance is greater than the first thermal conductance; The apparatus of claim 1 , configured such that the bypass thermal conductance is greater than the second thermal conductance.

5. The apparatus of claim 4 , wherein the thermal bypass path includes heat flow through the substrate and / or the circuit.

6. 5. The apparatus of claim 4, wherein the thermal bypass path includes heat flow through a thermal jumper mounted on the substrate to span a gap between the first connection member and the second connection member.

7. The device of claim 1 , further comprising a thermal jumper joined across the distal ends of the first and second connecting members.

8. the first portion is joined to the second portion by a first weld, and the second portion is joined to the third portion by a second weld; the proximal end of the first connecting member is positioned as close as possible to the first portion without overlapping a weld area of ​​the first weld; The apparatus of claim 1 , wherein the proximal end of the second connecting member is brought as close as possible to the third portion without overlapping a weld area of ​​the second weld.

9. The second portion has a temperature coefficient of electrical resistance in a temperature range of 20°C to 50°C: 0 to 10×10−6K−1 or 0 to −10×10−6K−1, or 0 to 20 x 10-6K-1 or 0 to -20 x 10-6K-1 10. The device of claim 1, comprising a material wherein:

10. The apparatus of claim 1 , wherein the second portion comprises a metal alloy including copper, nickel, and manganese.

11. the body of the second portion has a length along a first direction between the first portion and the third portion, a width along a second direction, and a thickness along a third direction; The device of claim 1 , wherein the first connecting member and the second connecting member have a thickness along the third direction that is less than the thickness of the body.

12. The main body, the first connecting member, and the second connecting member are compressively deforming a portion of a single piece of material to form a region of reduced thickness; forming the body of the second portion from the single-piece undeformed portion; forming the first connecting member and the second connecting member from the reduced thickness region; 12. The device of claim 11, formed from said single piece of said material by

13. The device of any preceding claim, wherein the body, the first connecting member and the second connecting member are formed from a single piece of material.

14. The device of any preceding claim, wherein the first connecting member and the second connecting member each include at least one section that is angled relative to the body.

15. The apparatus of any one of claims 1 to 12, wherein the first connecting member and the second connecting member each include at least one curved section.

16. The device of any preceding claim, wherein the first connecting member and the second connecting member each have a serpentine configuration.

17. The apparatus of any preceding claim, wherein the busbar connector is U-shaped.

18. The apparatus of any preceding claim, wherein the busbar connector is straight.

19. the body of the second portion has a length along a first direction between the first portion and the third portion, a width along a second direction, and a thickness along a third direction, and the extensions from the body of the first connecting member and the second connecting member have components parallel to the second direction; 13. The device of claim 1, wherein the first portion and the third portion have a maximum width along the second direction, the maximum width being sufficiently large such that neither the first connecting member nor the second connecting member protrudes beyond the width of the first portion and the third portion.

20. 20. The apparatus of claim 19, wherein the first portion and the third portion include a respective full-width section spaced from the second portion and a respective reduced-width section coupled to the second portion.

21. 21. The apparatus of claim 20, wherein a length of the respective reduced width sections of the first portion and the third portion along the first direction is configured to minimize sensitivity variation of the current sensor with temperature.

22. the first portion includes one or more through holes used to mechanically secure the bus bar connector to the substrate; and / or the third portion includes one or more through holes used to mechanically secure the bus bar connector to the substrate; An apparatus according to any preceding claim, wherein the size and location of any through-holes are configured to minimise change in sensitivity of the current sensor with temperature.

23. further comprising one or more temperature sensors; 13. The apparatus of claim 1, wherein the circuitry is configured to perform a temperature dependent sensitivity correction on the measured current based on the temperature measured by the one or more temperature sensors.

24. one or more further busbar connectors, each further busbar connector electrically connected in parallel with the busbar connector, the one or more further busbar connectors comprising a first portion, a second portion and a third portion, the second portion being formed from a material having a lower temperature coefficient of electrical resistance than the materials forming the first portion and the third portion, respectively; An apparatus according to any preceding claim, wherein the second part of each further busbar connector comprises a body having the same dimensions as the body of the busbar connector.

25. the first portion of the busbar connector and the first portion of the further busbar connector are provided in a single piece folded back on itself; and / or 25. The apparatus of claim 24, wherein the second portion of the busbar connector and the second portion of the further busbar connector are provided by the single piece folded back onto itself.

26. 25. The apparatus of claim 24, wherein the one or more further bus bar connectors are stacked in parallel with the bus bar connector.

27. 25. The apparatus of claim 24, wherein the second portion of at least one bus bar connector of the one or more further bus bar connectors is integrally formed with the respective body and includes first and second connecting members configured similarly to the first and second connecting members of the bus bar connector.

28. 13. The apparatus of any preceding claim, wherein the busbar connector has a maximum current carrying capacity of at least 20 amps.

29. the current sensor is constituted by the DC electric meter; The DC electric meter comprises: one or more further current sensors, each further current sensor being the same as the current sensor; a controller connected to the current sensor and each of the further current sensors and configured to record a respective energy consumption corresponding to each current sensor; The apparatus of any one of claims 1 to 12, further comprising:

30. The DC electric meter is connected to the current sensor, and the device further comprising one or more additional current sensors, each additional current sensor being the same as the current sensor; 13. The apparatus of any one of claims 1 to 12, wherein the DC electricity meter is connected to the current sensor and each of the one or more further current sensors via respective wired or wireless links and is configured to record the respective energy consumption corresponding to each current sensor.

31. an assembly including a first portion, a second portion, and a third portion, wherein the material forming the second portion has a temperature coefficient of electrical resistance that is smaller than the materials forming the first portion and the third portion, respectively; the second portion includes a body integrally formed with a first connecting member and a second connecting member, each connecting member having a proximal end joined to the body and a distal end, the connecting members configured such that when a first temperature difference exists between the respective proximal ends of the first connecting member and the second connecting member, a second temperature difference between the respective distal ends is less than or equal to 50% of the first temperature difference.

32. 32. The assembly of claim 31, wherein a closest spacing between the first connecting member and the second connecting member is less than a spacing between the respective proximal ends of the first connecting member and the second connecting member.

33. the first connecting member extends along a first path between the proximal end and the distal end, the first path having a first length, a first width of the first connecting member at each point along the first path being a maximum dimension of the first connecting member perpendicular to the first path at that point, and the first length being greater than or equal to three times the maximum first width along the first path; 33. The assembly of claim 31 or claim 32, wherein the second connecting member extends along a second path between the proximal end and the distal end, the second path having a second length, a second width of the second connecting member at each point along the second path being a maximum dimension of the second connecting member perpendicular to the second path at that point, and the second length being greater than or equal to three times the maximum second width along the second path.

34. Use of a device according to any one of claims 1 to 12 for recording energy consumption corresponding to one or more loads.

35. 1. A method of manufacturing a bus bar connector, comprising: receiving a feedstock including a first region connected to a third region via a second region, wherein a material forming the second region has a temperature coefficient of electrical resistance that is less than a temperature coefficient of electrical resistance of a material forming each of the first region and the third region; removing material from the feedstock; a first portion formed from the first region; a second portion formed from the second region and including a body integrally formed with a first connecting member and a second connecting member, each connecting member having a proximal end joining the body and a distal end projecting from the body; a third portion formed from the third region; and fabricating a busbar connector comprising: the first connecting member and the second connecting member are configured such that when a first temperature difference exists between the respective proximal ends of the first connecting member and the second connecting member, a second temperature difference between the respective distal ends is less than or equal to 50% of the first temperature difference.

36. the first connecting member extends along a first path between the proximal end and the distal end, the first path having a first length, a first width of the first connecting member at each point along the first path being a maximum dimension of the first connecting member perpendicular to the first path at that point, and the first length being greater than or equal to three times the maximum first width along the first path; 36. The method of claim 35, wherein the second connecting member extends along a second path between the proximal end and the distal end, the second path having a second length, a second width of the second connecting member at each point along the second path being a maximum dimension of the second connecting member perpendicular to the second path at that point, and the second length is greater than or equal to three times the maximum second width along the second path.

37. 36. The method of claim 35, wherein the material is removed from the feedstock by a shearing process.

38. 38. The method of claim 37, wherein the shearing process comprises one or more of stamping, die cutting, and fine blanking.

39. Removing material from the feedstock to fabricate the second portion comprises: compressively deforming a portion of the second region to form a reduced thickness region; forming the body of the second portion from the undeformed portion of the single piece; forming the first connecting member and the second connecting member from the reduced thickness region; 36. The method of claim 35, comprising:

40. 36. The method of claim 35, wherein the first region is welded to the second region and the second region is welded to the third region.

41. 36. The method of claim 35, wherein removing material from the feedstock to fabricate a bus bar connector comprises a series of stations, at each station material is removed from the feedstock to form one or more features of the bus bar connector.

42. 42. The method of any one of claims 35 to 41, wherein the stock material is in the form of a roll.

Images