Current sensor

Abstract

The present disclosure describes an electric vehicle comprising: an electrical conductor arranged to carry a drive current driving movement of the vehicle; and a current sensor arranged to measure a drive current in the electrical conductor, the current sensor comprising: a carrier extending around the conductor so as to face an opposite face of the electrical conductor; first and second Hall sensor packages mounted on the carrier at opposite sides of the conductor, each Hall sensor package being arranged to output a signal representative of a magnetic field at the package; and a differential amplifier mounted on the carrier, receiving the signals from the first and second Hall sensor packages, and combining the signals to provide at least one amplifier output representative of the drive current. The carrier may include a flexible PCB. The present disclosure also describes a method of measuring current.

Description

Technical Field

[0001] The present invention relates to the measurement of current in a conductor, such as the measurement of drive current within the powertrain of an electric vehicle. Background Art

[0002] Electric vehicles typically use multiple electrical conductors to carry drive current through the powertrain from a battery unit composed of one or more batteries or another power source, such as a fuel cell, to one or more electric motors, which are used to drive the wheels or other drive elements of the vehicle. The peak current can be very large, for example, typically in the range of about 10 to 1000 amperes, and the cross-sectional area of the electrical conductor may also be correspondingly large, for example, typically in the range of about 10 mm 2 to about 2000 mm 2 range. Precise control of the powertrain may require precise measurement of the drive current within these electrical conductors.

[0003] Precise measurement of large currents in conductors is also required in various other situations, such as in industrial facilities like factory production lines, chemical plants, and mining equipment; in power generation facilities like solar cell arrays, wind turbines, gas turbine power plants, and other power generation facilities, as well as in power grid transmission arrangements; and in various different types of vehicles, such as road vehicles, industrial vehicles, railway engines, ships, and aircraft.

[0004] There are various prior art arrangements for such current measurements. The HFTS series current sensors manufactured by LEM Holding SA use a ferrite ring flux concentrator surrounding the electrical conductor and a Hall effect sensor located at the gap within the flux concentrator ring, but they are large in size, difficult to install on in-situ conductors, and sensitive to background magnetic fields. The IMC-Hall current sensors manufactured by Melexis N.V. can be more easily installed on in-situ conductors, but they require the use of bulky magnetic shielding to reduce sensitivity to background magnetic fields and concentrate the magnetic field to be measured.

[0005] It is desirable to address the limitations of the relevant prior art. Summary of the Invention

[0006] The present invention provides a current sensor arranged to measure a current in an electrical conductor, the current sensor comprising: a carrier extending around the conductor so as to face two opposite faces or opposite points around the conductor; separate first and second Hall effect sensors or first and second Hall sensor packages or first and second Hall sensor components, mounted on the carrier at opposite faces or opposite points of the conductor or around the conductor, each Hall sensor being arranged to output a signal representative of the magnetic field at the respective sensor; and an amplifier or comparator, or more specifically a differential amplifier, also preferably mounted on the carrier, the amplifier or comparator being arranged to receive signals from the first and second Hall sensor packages and combine the signals to provide at least one amplifier output representative of the current in the conductor, the current being compensated to remove any background magnetic field common to the two Hall effect sensors.

[0007] More specifically, the current sensor may comprise: a flexible carrier having first and second regions, the flexible carrier being arranged to extend around the electrical conductor such that the first and second regions face respective opposite faces of the conductor; first and second Hall sensor packages or components mounted on the carrier in the respective first and second regions, each Hall sensor package being arranged to output a signal representative of the magnetic field at the Hall sensor package; and a differential amplifier mounted on the carrier, the differential amplifier being arranged to receive signals from the first and second Hall sensor packages and differentially combine the signals to provide at least one amplifier output representative of the current in the conductor.

[0008] The present invention can in particular be applied to measuring the drive current in an electric vehicle and can thus be applied to an electric vehicle which comprises: an electrical conductor arranged to carry the drive current for driving the vehicle, the electrical conductor having opposite faces; and a current sensor arranged to measure the drive current in the electrical conductor. The current sensor then comprises: a carrier extending around the conductor so as to face two opposite faces; first and second Hall sensor packages mounted on the carrier at opposite faces of the conductor, each Hall sensor package being arranged to output a signal representative of the magnetic field at the package; and a differential amplifier preferably also mounted on the carrier, the differential amplifier being arranged to receive signals from the first and second Hall sensor packages and differentially combine the signals to provide at least one amplifier output representative of the drive current.

[0009] The present invention also provides such an electric vehicle arranged to control the drive current in response to at least one amplifier output.

[0010] The carrier may comprise a flexible PCB, and the first and second Hall sensor packages and the differential amplifier may be mounted on the flexible PCB and be in electrical communication with each other via conductive wiring traces of the flexible PCB.

[0011] The carrier may also include at least first and second reinforcing elements, each reinforcing element being disposed between a respective face of the conductor and an adjacent portion of the flexible PCB. Such reinforcing elements can help to hold the Hall sensor package in a stable position relative to the conductor and close to the conductor.

[0012] Each Hall sensor package can be arranged to detect a magnetic field parallel to an adjacent face of the conductor, the magnetic field being caused by a drive current flowing in the conductor. By using a differential amplifier to vectorially add the output signals of the Hall sensors, the magnetic field caused by the current in the conductor will be added and any background magnetic field common to the two packages will be subtracted and thus removed from the amplifier output.

[0013] The first and second Hall sensor packages can be mounted on respective first and second planar regions of the carrier, and the first and second planar regions can be coupled by a curved region of the carrier such that each planar region can be located near an opposite face of the conductor.

[0014] The carrier may also include a connection region extending from one of the first and second planar regions, and an electrical connector mounted on the distal end of the connection region, the connection region carrying at least one amplifier output to the electrical connector for output from the sensor.

[0015] The electrical conductor can have a cross-sectional area of from about 10 mm 2 to about 2000 mm 2 more specifically from about 50 mm 2 to about 1000 mm 2 . The cross-sectional aspect ratio of the electrical conductor can be between 2 and 20 at least at the location of the current sensor, i.e., the lengths of the opposite faces are 2 to 20 times the spacing between these opposite faces.

[0016] An advantage of the sensor is that there is no need to provide any holes through the electrical conductor at the location of the sensor, such as between portions of the carrier extending around the conductor, or between the first and second Hall sensor packages, and the current in the conductor can be measured without providing them. Thus, the sensor can be used for any unmodified, reasonably accessible portion of the conductor.

[0017] Another advantage of the sensor is that there is no need for, and in fact no provision of, any flux concentrator assembly (e.g., a ferrite structure) adjacent to the electrical conductor near the Hall sensor package, e.g., within 2 cm of each Hall sensor package.

[0018] In other words, the present invention can also be described as providing a current sensor for measuring the current in an electrical conductor having opposite faces, the current sensor comprising: a flexible carrier having first and second regions, the flexible carrier being arranged to extend around the conductor such that the first and second regions face the respective opposite faces; first and second Hall sensor packages or components mounted on the carrier in the respective first and second regions, each Hall sensor package being arranged to output a signal representative of the magnetic field at that Hall sensor package; and a differential amplifier mounted on the carrier, the differential amplifier being arranged to receive the signals from the first and second Hall sensor packages and combine the signals to provide at least one amplifier output representative of the current.

[0019] The flexible carrier may further include one or more curved regions connecting the first and second planar regions, and connection regions connecting the first or second planar region to an electrical connector. The electrical connector is then arranged to output from the sensor at least one amplifier output representative of the current in the conductor.

[0020] The flexible carrier may include a flexible printed circuit board, referred to as a flexible PCB, and then the first and second Hall sensor packages, the differential amplifier, and the electrical connector can all be mounted on the flexible PCB and communicate electrically via the wiring traces of the flexible PCB as required.

[0021] The flexible carrier may include reinforcement elements coupled to the flexible PCB in each of the first and second planar regions.

[0022] The present invention also provides a method of constructing or manufacturing the sensor, and a method of using the sensor described herein, including mounting the sensor on a conductor and / or using the sensor to measure current. For example, the present invention provides a method of measuring the current in an electrical conductor having opposite faces, the method comprising: bending or winding the flexible carrier, mounting separate first and second Hall sensor packages or components on the flexible carrier around the conductor such that each Hall sensor package is adjacent to one of the opposite faces and provides an output signal representative of the local magnetic field caused by the current; receiving the output signals at a differential amplifier mounted on the carrier, the differential amplifier being arranged to combine the output signals to generate at least one amplifier output, the amplifier output representing the current compensated to remove the influence of the background magnetic field common to the two Hall sensor packages; and outputting the amplifier output from the sensor.

[0023] As described above, the flexible carrier may include a flexible PCB on which the Hall sensor packages and optionally also the differential amplifier are mounted. For such a device, the electrical conductor may be a conductor carrying drive current within the powertrain of an electric vehicle. Description of the Drawings

[0024] Embodiments of the present invention will now be described with reference to the accompanying drawings by way of example only:

[0025] Figure 1 An electric vehicle is shown in which one or more current sensors embodying the present invention are deployed and operated;

[0026] Figure 2 A current sensor for measuring current in a conductor is shown in a schematic cross-sectional view, for example in the context of an electric vehicle; Figure 1 of an electric vehicle;

[0027] Figure 3 An electronic circuit is provided that can be used as part of or is external to a current sensor; Figure 1 or Figure 2 of a current sensor;

[0028] Figure 4 An embodiment of a current sensor is shown in a side view / cross-sectional view; Figure 2 or Figure 3 before it is deployed on a conductor for current measurement;

[0029] Figure 5 A detailed embodiment of a current sensor is shown in a perspective view; and Figures 2 to 4 of any one of;

[0030] Figure 6 Steps of a method for deploying and / or operating a current sensor are shown; Figures 2 to 5 of any one of; Detailed Description

[0031] Figure 1 A plan view of an electric vehicle 10 is schematically shown. The electric vehicle 10 includes a powertrain 12 that includes one or more electric motors 14 for driving wheels 16 or other drive elements of the vehicle, optionally via a mechanical transmission 18, and includes one or more batteries 20 for providing drive current used by the electric motors 14. To regulate the drive current to be delivered to the one or more electric motors 14 in the correct form, the powertrain 12 also includes power electronics 22, which itself may include one or more DC-DC converters, DC-AC inverters, and other elements.

[0032] A variety of electronic systems can be provided within the electric vehicle 10 and, optionally, at least partially outside the electric vehicle 10 to provide appropriate monitoring and / or control of the powertrain, such as the battery management system 24 and the powertrain electronic control unit 26. Such electronic systems can benefit from accurately measuring the drive current at various points within the powertrain, which can be anywhere from within one or more batteries 20 to within one or more electric motors 14. To this end, the electric vehicle 10 includes one or more current sensors 30 that are arranged to measure the drive current flowing in an electrical conductor that forms part of the powertrain 12, and these current sensors 30 can then provide the measured value of the drive current to any or all of the electronic systems, such as the battery management system 24 and the powertrain electronic control unit 26.

[0033] Note that other embodiments may relate to the current sensor 30, whether it is mounted near or not near the electrical conductor, or to current sensors in various other application areas that have been used or are used to measure current within an electrical conductor, such as the current sensor within the electrical conductor described in more detail below. These other application areas may include factory production lines, chemical plants, and mining equipment; power generation facilities, such as solar cell arrays, wind turbines, gas turbine power plants, and other power generation facilities, as well as power grid transmission arrangements; and various different types of vehicles, such as road vehicles, industrial vehicles, railway engines, ships, and aircraft.

[0034] Figure 2 The current sensor 30 is shown in a schematic and quasi-cross-sectional view and can be used in Figure 1 electric vehicles, or in fact in various other situations where it is desired to measure the current within an electrical conductor. The current sensor 30 is used to measure the current flowing within the electrical conductor 26, which, in the Figure 1 context, is the drive current within an electrical conductor that forms part of the powertrain 12. At least at the location where the current sensor 30 is located, the electrical conductor has opposite and generally parallel, generally planar main faces 28’, 28”. The electrical conductor can, for example, have a generally rectangular cross-section, or it can have opposite planar main faces and opposite curved secondary faces, or some other structure or cross-section. The present invention can also be used with conductors having other cross-sectional shapes, such as circular, elliptical, or other more complex shapes, in which case, when we refer to opposite faces, it is understood to mean opposite points around the conductor.

[0035] In a typical vehicle powertrain 12, at least at the location where the current sensor is located, the cross-sectional area of the electrical conductor 26 may typically be about 10 mm 2 to 2000 mm 2 , or about 50 mm 2 to 1000 mm 2。Typical cross-sectional aspect ratios, such as Figure 2 the ratio of width to height as shown in the cross-section of Figure 2 can be from about 2 to about 20, or from about 4 to about 10, such that with this aspect ratio,

[0036] the cross-section of the main faces 28’, 28” shown is longer than the cross-section of the secondary faces 29’, 29”.

[0037] As Figure 2 shown, the current sensor 30 includes a carrier 32 that extends around the conductor 26, thereby including a first region 34’ (described hereinafter as a first planar region because it is generally substantially flat to conform to the lower surface of the conductor), which at least partially faces one of the opposing main faces 28’ of the conductor, and including a second region 34” (for the same reason, described hereinafter as a second planar region), which at least partially faces the other opposing main face 28”. For example, the first and second planar regions of the carrier 32 may each extend over at least 60% and more preferably 80% of the width of their respective main faces. In Figure 2 it, the first and second planar regions each extend over approximately 100% of their respective main faces.

[0038] Thus, it can be said that the carrier 32 wraps around the conductor 26, although typically as Figure 2 shown, the carrier will extend or wrap around one of the secondary faces 29” of the conductor, but not around the other secondary face 29’. In this way, the cross-section of the carrier 32 can be described as having a U-shape, with the electrical conductor at least partially located within the U-shape. The first and second planar regions 34’, 34” of the carrier 32 face opposing faces of the conductor and are then coupled by a curved region 46 of the carrier, where the carrier has an appropriate radius of curvature.

[0039] The carrier may also include a connection region 48 that, when installed as Figure 2 shown, extends away from the conductor, for example, away from one of the first and second planar regions 34’, 34” (shown in Figure 2 as extending away from the second planar region 34”) to provide a connection between the sensor 30 and an external electronic device, such as via an electrical connector 42 or a plug.

[0040] When as Figure 2When installed as shown, either or both of the first and second planar regions 34', 34'' of the carrier 32 can be in direct contact with the respective major faces 28', 28'' of the conductor, or can be separated thereat, e.g., by one or more air gaps, spacer structures or materials, or reinforcement elements 35', 35'', as further described below.

[0041] The carrier 32 can be provided as an integral rigid structure, constructed in its final rigid form and arranged to fit around the conductor, as Figure 2 shown. However, for more flexible and convenient installation, the carrier can be constructed as a single and / or continuous and / or planar flexible component. Such a component preferably has sufficient flexibility to be constructed or fabricated in a flat, open configuration (see Figure 4 ), so as to be subsequently bent or wound around the conductor, as Figure 2 shown. To this end, the carrier can have a thickness of less than 2 mm or less than 1 mm. Specifically, as described below, if provided as a flexible, continuous component, the carrier can be implemented using a flexible printed circuit board (PCB) or the carrier can include a flexible printed circuit board (PCB).

[0042] Especially if the carrier is implemented as a flexible, continuous component, the carrier can be fixed to the conductor using a suitable clip (not shown in the figures), e.g., a clip that holds the first and second planar regions on opposite major faces of the conductor, by bundling the entire first and second planar regions and the included portion of the conductor with a bundling means such as shrink wrap, or by various other means.

[0043] To measure the drive current flowing in the conductor 26, the current sensor 30 includes separate first and second Hall sensor packages or components 36', 36'', which are mounted on the carrier, at the first and second planar regions 34', 34'', and thus close to or adjacent to the respective opposite major faces 28', 28'', as Figure 2 shown. Each Hall sensor package 36', 36'' can preferably be located at the center with respect to the respective adjacent face of the conductor, e.g., the center point or Hall effect region 37 of each sensor package is located between 40% and 60% of the conductor width. Each Hall sensor package 36', 36'' can preferably be located very close to the adjacent face of the conductor, e.g., the center point or Hall effect region 37 of each sensor package is located between 1 mm and 10 mm or between 1 mm and 20 mm from the conductor surface.

[0044] Each Hall sensor package 36’, 36” measures the magnetic field at the respective package using the Hall effect, thus providing an electrical output signal representative of the magnetic field near or adjacent to the respective opposite faces of the conductor. Each Hall sensor package is a separate semiconductor package and can typically be implemented as a dual in-line package (DIL or DIP). The MLX 91216 Hall sensor package produced by Melexis N.V. is an example of a Hall sensor package suitable for this purpose.

[0045] The electrical outputs of the two Hall sensor packages 36’, 36” are received at a differential amplifier 38, which is preferably also mounted on the carrier (although it can also be mounted elsewhere, such as Figure 3 in the external electronics shown). The differential amplifier 38 is partially visible Figure 2 in, and is mounted in the second planar region 34” of the carrier 32 near the Hall sensor package 36”. The differential amplifier is typically provided as another separate semiconductor package, mounted separately from the two Hall sensor packages on the carrier, and can be provided as a fully differential operational amplifier, such as the Analog Devices LTC6363 amplifier. Other electronic components can also be mounted on the carrier, as described below in connection with Figure 3 the description.

[0046] The differential amplifier 38 is arranged to combine the output signals of the two Hall sensor packages 36’, 36” to provide an amplifier output 40, which represents the magnetic field near the conductor, but is affected by the longer range background magnetic fields common to the two Hall sensor packages, which are not caused by currents that have been removed by the differential action of the amplifier 38. Thus, the amplifier output 40 can be used as an accurate measurement or representation of the current flowing in the conductor.

[0047] When current flows in a particular direction along the conductor, the magnetic field lines generated encircle the conductor, and thus the vector magnetic field B at one Hall sensor package due to the current to be measured is in the opposite direction to the vector magnetic field -B at the other Hall sensor package (if both magnetic fields are represented in the same Cartesian coordinate system). If both also contain the same, common background or noise magnetic field vector element N, then the signals measured at each Hall sensor package are B + N and -B + N, and thus the two measurements are subtracted at the differential amplifier to provide a differential output, which, with the common background N removed, gives a measured magnetic field of ±2B. Since the measured magnetic field ±2B represented by the amplifier output 40 is proportional to the current in the conductor, the current can be derived as a simple linear multiple of this magnetic field.

[0048] The amplifier output 40 can be transmitted along the carrier 32, for example along the connection area 48 of the carrier to the electrical connector 42, from where it can be transmitted to the vehicle's electronic systems, such as the battery management system 24 and the powertrain electronic control unit 26, for further use as described above, for example to control aspects of the powertrain 12, such as providing control of the current in the conductor 26. In fact, the amplifier output 40 itself can be provided by a differential amplifier as two output signals, commonly referred to as differential outputs. Such differential outputs are essentially two versions of the same signal, having equal amplitudes but opposite polarities, and can be easily provided by a fully differential operational amplifier, such as the Analog Devices LTC6363 amplifier described above. Combining these differential outputs together at a remote point, such as Figure 3 at the analog-to-digital converter 66 in can reduce or remove the common-mode noise affecting the signal during transmission to that point.

[0049] Generally, the amplifier output 40 can be digitized using an analog-to-digital converter. This can be done within the sensor 30, as Figure 2 shown, but more typically, it is done elsewhere after the differential outputs 40 are output via the connector 42. Other signals and electrical connections can be provided via the electrical connector 42, such as a power supply 44 for the operation of other aspects of the Hall sensor package, differential amplifier, and current sensor 30.

[0050] Figure 3 Schematically shows how the amplifier output 40 is formed from the output signals of two Hall sensor packages mounted on the carrier 32 (the carrier is not shown in the figure for ease of illustration), and how the amplifier output is subsequently processed and passed on to other electronic systems. Two Hall sensor packages 36’, 36” are depicted as being located near the respective opposite faces 28’, 28” of the electrical conductor 26, where the current to be measured is depicted as flowing into the plane of the figure. The output signals from each Hall sensor package are transmitted to conditioning electronics also mounted on the carrier 32 (not shown), such as respective noise reduction filters 52’, 52”, from where the conditioned output signals are transmitted as differential inputs + and - to a differential amplifier 38, typically provided by an operational amplifier package. The amplifier output 40 then represents the voltage difference between the signals from the Hall sensor package signals, and as Figure 3 shown, this can be provided as differential outputs 40’, 40” (also labeled + and -) and transmitted to the electrical connector 42 (where they are shown as S+ and S-).

[0051] The sensor may also include a local power supply 54, which includes one or more electronic components mounted on the carrier and receives power from the electrical connector 42 (shown here as the ground G and power P connections, e.g., +10V relative to ground), and delivers regulated power 56 to each Hall sensor package and differential amplifier. Although Figure 3 not shown in Figure 3 , the local power supply 54 may also deliver positive and negative reference voltages to the electrical connector 42 for more stable measurement of the current in the conductor 26 through the connection electronics 60 described below.

[0052] Figure 3 The connection electronics 60 shown in

[0052] is connected to the sensor 30 via a cable 62 coupled to the electrical connector 42 and includes an external power supply 64 for delivering the ground G and power P connections to the sensor 30 and for receiving the differential amplifier outputs 40', 40", and also optionally the positive and negative reference voltages if provided by the local power supply 54 of the sensor. These outputs are forwarded to an analog-to-digital converter 66, which provides a digital output I c representing the current in the conductor 26, and is forwarded to a separate overcurrent detector 68, which is arranged separately to detect whether the current in the conductor 26 exceeds a threshold, and if so, outputs an overcurrent flag F. The overcurrent flag F can be used by other electronic systems in various ways, e.g., to cut off the current in the conductor if the current in the conductor exceeds a safe level.

[0053] As described above, the carrier 32 may specifically include or be provided by a flexible PCB, and then the Hall sensor packages, the optional differential amplifier, and the optional other components may be mounted on the flexible PCB and electrically communicate with each other and with the electrical connector 42 via the conductive wiring traces of the flexible PCB as needed. The other components are, for example, components forming the local power supply 54 and the noise reduction filters 52', 52".

[0054] In particular, if provided as a flexible and continuous element, the carrier may also include separate reinforcing elements 35', 35" in first and second planar regions 34', 34" of the carrier that are opposite the major faces 28', 28" of the conductor, respectively. Specifically, if the carrier includes a flexible PCB, each such reinforcing element may be coupled or adhered to respective first and second planar regions 34', 34" of the flexible PCB that are opposite the major faces of the conductor. These reinforcing elements 35', 35" may be formed of an insulator, such as polyimide, and are used both to provide enhanced electrical insulation between the flexible PCB and the conductor and to increase the stiffness of the flexible carrier in the relative regions, such that the carrier in these regions remains in more stable contact with the conductor in these regions. Such reinforcing elements 35', 35" are provided only at positions on the opposite faces of the carrier facing the conductor, and optionally in a limited number of other regions where increased stiffness is desired, such as near the electrical connector 42, such that the carrier can be more easily bent in the bending regions 46 and the connection regions 48.

[0055] Figure 4 A schematic and cross-sectional view (not to scale in terms of dimensions and sizes) shows how the carrier 32 provided in the above flexible, planar, and continuous form can be used to provide Figure 2 the sensor 30 therein, such as using a flexible PCB 50 having suitable reinforcing elements 35', 35", 35'" as described above. In Figure 4 the figure, the carrier 32 is shown in an open planar form and then deployed by bending or winding around the conductor, as Figure 2 shown. The flexible PCB 50 can generally be formed of polyimide or other suitable materials and have conductive wiring traces, further insulating layers, etc., as are typical features of a flexible PCB, i.e., having a thickness of about 0.1 - 1.0 mm, or more typically about 0.2 mm. The Hall sensor packages 36', 36" are then mounted to the flexible PCB 50 at appropriate positions within the planar regions 34', 34" such that once the sensor is wound around the conductor, these Hall sensor packages 36', 36" are close to the two opposite faces of the conductor, as described above in connection with 2.

[0056] The reinforcing elements 35', 35" can also be formed of polyimide or other suitable materials, having a thickness of about 0.1 - 1.0 mm or more typically about 0.25 mm, and are also provided on the flexible PCB 50, adjacent to and on opposite sides of the Hall sensor packages 36', 36", and are provided in the first and second planar regions 34', 34", wherein the first and second planar regions are intended to be adjacent to the first and second main faces 28', 28" of the conductor. These reinforcing elements 35', 35" help to hold the Hall sensor packages in a stable position relative to the conductor, and can also help to ensure that adjacent circuit components are stably and reliably fixed in place, as well as provide additional electrical insulation between the conductor and the electronic components of the sensor provided on the carrier.

[0057] The bent region 46 of the flexible PCB 50 does not include any reinforcing elements in order to better allow the carrier 32 to be wrapped from one face of the conductor to the other. Similarly, most of the connection region 48 does not include any reinforcing elements in order to maintain the flexibility of the connection region 48 for flexible and easy installation of the sensor, but another reinforcing element 35'" can be provided near the electrical connector 42 at the end of the connection region 48 to improve the reliability of this connection.

[0058] Other electronic components, such as the differential amplifier 38, the local power supply 54, and the noise reduction filters 52', 52", are also mounted on the flexible PCB, preferably in regions of the flexible PCB where reinforcing elements are also provided.

[0059] Figure 5 A version of the sensor 30 from the previous figures is depicted in perspective, and in particular shows how the first planar region 34', the bent region 46, the second planar region 34", and the connection region 48 can be geometrically related and arranged when the sensor is in a deployed configuration around the electrical conductor to measure the current flowing in the sensor. For clarity, the electrical conductor is omitted from this figure, but two long arrows labeled I show the current in such a conductor, which can be measured by the sensor. Also shown are the second Hall sensor package 36", the differential amplifier 38, and other electronic components.

[0060] The present invention also provides various methods for manufacturing and using the sensor as described above. For example, Figure 6 A method of measuring the current in an electrical conductor having the properties as described above is shown, and uses the sensor as described above.

[0061] In step 110 of the method, the carrier of the sensor is deployed by being mounted on a conductor. If the carrier is a flexible carrier, such as including the flexible PCB as described above, with or without the reinforcing element, this may involve bending or winding the carrier into a U-shape around the conductor such that each Hall sensor package mounted on the carrier is adjacent to one of the opposing major faces of the conductor surface or is located at opposing points on the conductor surface.

[0062] The method continues in step 120 to operate the sensors such that each Hall sensor package provides an output signal representative of the local magnetic field at the package, which in turn represents the current in the conductor affected by any background magnetic field from other sources. This step may involve, for example, ensuring that the sensors are connected to a suitable power source, such as Figure 3 the external power supply 64 in

[0063] via cable 62 and electrical connector 42, and providing any control signals as required.

[0064] At step 130, the output signals of two Hall sensor packages are received at a differential amplifier mounted on the carrier, and the differential amplifier vectorially combines these output signals to generate at least one amplifier output that represents the current in the conductor but is compensated to remove the effect of any background magnetic field common to the two Hall sensor packages. It should be noted that since the magnetic field generated by the current to be measured is in opposite directions at each Hall sensor package because they are located at opposing points or on opposing faces of the conductor, while any background field can be assumed to be in approximately the same direction and of approximately the same magnitude at the two points, vectorially subtracting the two measured fields produces an output proportional to the current to be measured that has been compensated to remove the background magnetic field.

[0064] At step 140, the amplifier output is output from the sensor, for example via an electrical connector, for further use, which may involve further conditioning or compensation steps as well as analog-to-digital conversion.

[0065] At step 150, the conditioned and digitized amplifier output is then used as a measurement of the current in the conductor, for example to provide control of the current or for other purposes. In Figure 1 the context of an electric vehicle application of

[0066] Although specific embodiments have been described in detail, those skilled in the art will recognize that various modifications and changes can be made to these embodiments without departing from the scope of the invention. For example, although the sensor 30 has been primarily described in the context of measuring the drive current in the powertrain of an electric vehicle, it can be used in a variety of other contexts and applications for measuring current in a conductor.

[0067] For example, sensors have been described as being suitable for measuring current in a conductor having opposing faces, such as a rectangular or similar shaped conductor, where the opposing faces are, for example, parallel and flat opposing faces. However, the present invention can also be applied to measuring current in a conductor having other cross-sectional shapes, such as circular, oval or more complex cross-sections, where two Hall effect packages are disposed at opposing sides, opposing faces or opposing points of the conductor, or indeed three or more such packages are used and disposed such that a suitable vector combination of the detected fields tends to cancel any background field common to all the Hall effect packages.

[0068] Although the sensor 30 has been described as being deployed on an electrical conductor through which the current to be measured flows, embodiments of the present invention also relate to the sensor itself, such as the sensor before any such installation or deployment.

Claims

1. An electric vehicle comprising: an electrical conductor arranged to carry a drive current for driving the vehicle in motion, the electrical conductor having opposing faces; as well as a current sensor arranged to measure a drive current in the electrical conductor, the current sensor comprising: a carrier extending around the conductor so as to face the two opposing surfaces; first and second Hall sensor packages mounted on said carrier at opposite sides of said conductor, each Hall sensor package being arranged to output a signal representative of a magnetic field at said package; A differential amplifier is mounted on the carrier, the differential amplifier being arranged to receive signals from the first and second Hall sensor packages and to combine the signals to provide at least one amplifier output representative of the drive current.

2. The electric vehicle according to claim 1, wherein: The carrier includes a flexible printed circuit board (flexible PCB), and the first and second Hall sensor packages and the differential amplifier are mounted on the flexible PCB and are in electrical communication with each other via the flexible PCB.

3. The electric vehicle according to claim 2, wherein: The carrier further comprises at least first and second reinforcement elements, each reinforcement element being disposed between a respective one of the faces of the conductor and an adjacent portion of the flexible PCB.

4. An electric vehicle according to any one of the preceding claims, wherein: Each Hall sensor package is arranged to detect a magnetic field parallel to an adjacent face of the conductor, the magnetic field being caused by a drive current flowing in the conductor.

5. An electric vehicle according to any one of the preceding claims, wherein: The first and second Hall sensor packages are mounted on first and second planar regions of the carrier, respectively, and the first and second planar regions are coupled through a bent region of the carrier.

6. The electric vehicle according to claim 5, wherein: The carrier further includes a connection region extending from one of the first and second planar regions, and an electrical connector mounted on a distal end of the connection region, the connection region carrying the at least one amplifier output to the electrical connector for output from the sensor.

7. An electric vehicle according to any one of the preceding claims, wherein: The electrical conductor has one or more of the following: a position from 50 mm to 100 mm at the current sensor; 2 To about 1000mm 2 and a cross-sectional aspect ratio of the length of the opposing faces to the spacing between the opposing faces of between 2 to 20.

8. An electric vehicle according to any one of the preceding claims, wherein: There are no holes through the electrical conductor between portions of the carrier extending around the conductor, or there are no holes through the electrical conductor between the first and second Hall sensor packages.

9. An electric vehicle according to any one of the preceding claims, wherein: The sensor does not include any magnetic flux concentrator components adjacent to the electrical conductor.

10. An electric vehicle according to any one of the preceding claims, wherein: The vehicle is arranged to control the drive current in response to the at least one amplifier output.

11. A current sensor for measuring current in an electrical conductor having opposing faces, the current sensor comprising: a flexible carrier having first and second planar regions, the flexible carrier being arranged to extend around the conductor such that the first and second planar regions face respective opposite faces; first and second Hall sensor packages mounted on the carrier, located in the first and second planar regions, respectively, each Hall sensor package being arranged to output a signal representative of a magnetic field at the Hall sensor package; as well as A differential amplifier is mounted on the carrier, the differential amplifier being arranged to receive signals from the first and second Hall sensor packages and to combine the signals to provide at least one amplifier output representative of the current.

12. The current sensor according to claim 11, wherein: The flexible carrier further comprises a curved region connecting the first and second planar regions.

13. The current sensor according to claim 11 or 12, wherein: The flexible carrier further comprises a connection area connecting one of the first or second planar areas to an electrical connector arranged to output the at least one amplifier output representing the electrical current.

14. The current sensor according to claim 13, wherein: The flexible carrier comprises a flexible printed circuit board (PCB), and wherein the first and second Hall sensor packages, the differential amplifier and the electrical connector are in electrical communication via routing traces of the flexible PCB.

15. The current sensor according to any one of claims 11 to 14, further comprising a reinforcement element coupled to the flexible PCB in each of the first and second planar regions.

16. An electric vehicle, comprising: an electrical conductor arranged to carry an electric current within a powertrain of the electric vehicle; as well as A current sensor as claimed in any one of claims 11 to 15, arranged to measure the current in the electrical conductor.

17. A method of measuring current in an electrical conductor having opposing faces, the method comprising: bending or wrapping a flexible carrier on which first and second Hall sensor packages are mounted around the conductor so that each Hall sensor package is adjacent to a respective one of the opposing faces and provides an output signal representative of a local magnetic field caused by the current; receiving the output signals at a differential amplifier mounted on the carrier, the differential amplifier being arranged to combine the output signals to generate at least one amplifier output representing a current compensated to remove the effects of a background magnetic field common to the two Hall sensor packages; and The amplifier output is output from the sensor.

18. The method according to claim 17, wherein: The flexible carrier includes a flexible PCB, and the Hall sensor package and the differential amplifier are mounted on the flexible PCB.

19. The method according to claim 17 or 18, wherein: The electrical conductor is arranged to carry a drive current within a powertrain of an electric vehicle.

20. The method according to any one of claims 17 to 19, wherein: One or more of the following exists: there is no hole through the electrical conductor adjacent to the first and second Hall sensor packages; and there is no magnetic flux concentrator assembly adjacent to the first and second Hall sensor packages.

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