Current Sensors for Printed Circuit Boards

Abstract

A current sensor (100) is incorporated into a printed circuit board (PCB) (102) for sensing a current (104) flowing through a first conductive path (106). The current sensor (100) comprises a first conductive winding (110) forming an open shape (112) in the plane of the PCB (102), the open shape (112) having a first end (114a) and a second end (114b) and defining a sensing area (116) in the plane of the PCB (102) for sensing a current (104) flowing through the first conductive path (106) disposed within the sensing area (116). The first conductive winding (110) is formed from a conductive portion having multiple turns extending across the thickness (d) of the PCB (102), and the first conductive winding (110) is spaced from an obstacle (108) in the PCB (102) by at least an insulation distance (118) from the first end (114a) to the obstacle (108).

Description

[Technical field]

[0001] The present invention relates to a sensor for sensing or measuring electric current, also called a current sensor, and in particular to a current sensor for incorporation into a printed circuit board (PCB). [Background technology]

[0002] Current sensors are used in a variety of electronic situations where it is desirable to measure the current flowing through a conductive path. Desirable characteristics for the current may include high sensitivity and accuracy, a wide range of operating frequencies (also called "wide bandwidth"), and high resistance to environmental interference, to name a few.

[0003] There are two prior art techniques for sensing current: shunt resistors and magnetic field sensors.

[0004] A shunt resistor sensor includes a resistor of known resistance, commonly referred to as a "shunt," that is electrically connected to a portion of an electrical circuit where a current measurement is desired. Using Ohm's law, the voltage drop measured across the shunt can be used as an indication of the current flowing through it. However, at high currents, high power consumption can result in significant heating of the shunt, reducing the accuracy of the current sensor. Additionally, power consumption is itself a loss and is therefore undesirable.

[0005] Magnetic field sensors can be used as current sensors because a current flowing through a conductive path generates a magnetic field proportional to the current. Such sensors can use Faraday's law or the Hall effect to detect an induced magnetic field. Unlike shunt resistors, magnetic-based current sensors do not need to be electrically connected to the component whose current is being measured. They are therefore desirable, for example, in situations where electrical isolation between components is required or in high current applications.

[0006] Electronic components mounted in dense or crowded environments may not generally have the space required to mount a conventional current sensor around them. Obstructions such as electrical terminals, screws in the PCB, and / or other components may make it difficult to mount a current sensor to components near these obstructions. This is especially true for situations where the current sensor is embedded into a PCB.

[0007] There have been some attempts to incorporate current sensors into printed circuit boards (PCBs). PCBs are generally small in size, but as technology advances and human efforts towards functional density increase, they are becoming smaller and smaller, so component miniaturization needs to be considered when incorporating components into a PCB.

[0008] The physical characteristics of some components may change as the components are miniaturized, so miniaturization may not be as simple as making each element of the component smaller. Furthermore, certain applications that require the use of PCBs with miniaturized components may not result in proper functioning of these components throughout their operating range. One example is the increasing demand for high bandwidth current sensing when using silicon carbide based semiconductors and taking advantage of the fast switching characteristics of this type of material. Thus, further changes in current sensors will be required to ensure proper functioning of miniaturized components when implemented in a wide range of applications.

[0009] Techniques such as "trace resistance sensing" are used as a space-saving construction of current sensors, whereby the shunt resistor is replaced by a trace (e.g., copper) in a PCB that has a known inherent resistance. The operation of such sensors can be enhanced through the use of isolation amplifiers or other post-processing techniques. Summary of the Invention

[0010] The present disclosure provides a current sensor for sensing current flowing through conductive paths in a PCB with improved accuracy and high bandwidth.

[0011] According to a first aspect, there is provided a current sensor incorporated into a printed circuit board (PCB) for sensing a current through a first conductive path, the current sensor comprising a first conductive winding forming an open shape in a plane of the PCB, the open shape having a first end and a second end and defining a sensing area in the plane of the PCB for sensing a current through a first conductive path disposed within the sensing area, the first conductive winding formed from a conductive portion having a plurality of turns extending across a thickness of the PCB, the first conductive winding being spaced from an obstacle in the PCB by at least an insulation distance from the first end to the obstacle.

[0012] The conductive path may be a connecting wire, a conductive portion of an electrical component in a PCB, or a similar component that carries a current that is desired to be sensed. For example, the first conductive path may be a pin or terminal of an electronic device, such as a semiconductor transistor (i.e., a silicon transistor, a silicon carbide transistor, or a high power semiconductor transistor, etc.).

[0013] The first conductive winding is formed from a conductive portion as a meandering wire (copper, aluminum or some other conductive material) having multiple turns extending across the thickness of the PCB. The multiple turns may comprise between 4 and 100 turns, or preferably between 8 and 32 turns, to further increase the bandwidth and frequency response of the current sensor.

[0014] Since the conductive path will have circular (or nearly circular) magnetic field lines radiating therefrom, the turns of the conductive winding are arranged within the PCB to surround at least a portion of these magnetic field lines, i.e., when viewed from a cross section perpendicular to the length of the conductive winding (i.e., extending between the two ends of the open shape of the winding), the turns of the conductive winding are arranged to collect magnetic flux such that an electromotive force (EMF) is generated in the first conductive winding by the current in the first conductive path (i.e., by Faraday's law of electromagnetic induction).

[0015] The electromotive force generated in the conductive winding then appears as a voltage signal across the conductive portion on which the conductive winding is formed. In some examples, the first conductive winding is electrically connected to an integrating circuit that generates an output voltage signal indicative of the current in the first conductive path. The electrical connection of the integrating circuit may be across an electrical terminal at one end of the conductive portion on which the conductive winding is formed, for example. Additionally or alternatively, the voltage signal from the conductive winding may be provided to a processing module that may perform the integration by software means. Since the integrated voltage is proportional to the current, i.e. a measure of the current value of the current flowing through the conductive path, the integral value of the voltage signal allows the current value to be determined.

[0016] According to some examples, the conductive part on which the conductive winding is formed may comprise a first electrical terminal and a second electrical terminal, for example at either end of the length of the conductive part. These two electrical terminals may advantageously be located together at the first end or the second end of the open shape of the conductive winding (in a plan view of the PCB), so that the electrical terminals can be easily electrically connected to other components (for example an integrated circuit as described above).

[0017] To achieve this, the second electrical terminal may be returned to the same end as the first terminal along the shape of the conductive winding, allowing the current sensor to remain closely packed in its structure and avoid obstacles when electrical connection between the terminals is required while still cancelling magnetic fields (i.e. interference) in the Z direction.

[0018] The first conductive winding forms an open shape in the plane of the PCB having a first end and a second end. The open shape may be any open shape suitable to allow an insulating distance from at least the first end to an obstacle in the PCB while defining a sensing area surrounding the conductive path. For example, the open shape may be an arc such as an elliptical arc, a circular arc (i.e., any portion of a circle or ellipse taken from a complete circle or ellipse), or a U-shape (with a curved or flat bottom), or an open polygon such as an open square or octagon (which may be referred to as a piecewise rectilinear shape). The open shape is formed in the plane of the PCB at least in the sense that the first conductive winding has an axis (e.g., along its length) that is arranged to form an open shape when viewed from above or below the PCB. The open shape may also be formed through its extension in the plane of the PCB (e.g., as a width or thickness of the shape) to form a region of a ring when viewed from above or below, for example in the case of an arc. That is, the open shape is formed in the plane of the PCB independent of the internal structure of the first conductive winding, e.g., independent of turns extending across the thickness of the PCB. The open shape may be optimized for maximum magnetic flux collection, ease of assembly, obstacle avoidance, and / or other desirable characteristics.

[0019] The sensing area defined by the open shape of the first conductive winding is the area through which current can pass and generate an electromotive force, i.e., the area through which the current flowing in the conductive path can be sensed. The current sensor is positioned close enough to the conductive path so that the current flowing therethrough can be sensed. Preferably, the conductive winding of the current sensor is shaped to maximize collection of magnetic flux generated by the current.

[0020] The current sensor advantageously has an open shape such that it can space away from (i.e., avoid) obstacles in the PCB. According to some examples, the obstacles may be mechanical obstacles such as fixed or bonded points on the PCB (screws, nails, fasteners, etc.) or edges or openings in the PCB (e.g., gaps or through-holes machined into the PCB, or simply the boundaries of its edges).

[0021] According to some examples, the obstacle may be a second conductive path having a different potential than the potential of the first conductive path. In these examples, the insulation distance may correspond to the distance from the first end to the second conductive path to suppress electrical interference between the second conductive path and the first conductive winding. Since the accuracy of the current sensor depends on the ability of the conductive winding to collect the magnetic flux generated by the current, it is preferable that the magnetic flux or other electromagnetic signals do not cause electrical interference in the conductive winding, as this may affect the output voltage signal and therefore the accuracy of the measured current. Furthermore, if the second conductive path has a different potential than the first conductive path, a potential risk of electrical arcing exists. Other forms of electrical interference include leakage current and / or material degradation over the life of the current sensor.

[0022] In the example where the obstacle is a second conductive path, the current sensor may be positioned such that magnetic flux emanating from a current flowing through the second conductive path does not substantially affect the amount of current measured from the current sensor. For example, the first end and the second end may define an axis of the opening passing through the first end and the second end, and a midpoint on that axis between the first end and the second end. The axis of the opening may be considered as a line spanning the open portion of the open shape of the conductive winding. The first end and the second end of the open shape may be positioned relative to the second conductive path such that an axis perpendicular to the axis of the opening and passing through the midpoint coincides with the location of the second conductive path. In this way, all (or most) of the magnetic field lines passing through the turns of the conductive winding in one direction (thereby generating an electromotive force) will substantially pass through the turns of the conductive winding in (approximately) the opposite direction, generating another electromotive force that substantially cancels the first electromotive force. However, it will be understood that "strictly perpendicular" is also ideal, and thus some deviation from strictly perpendicular is acceptable without substantially compromising the accuracy of the amount of current measured.

[0023] In some examples, a further technique for reducing interference in the conductive winding is to protect the conductive winding with shielding. For example, a shielding material may be positioned to at least partially shield the first conductive winding from sources of electromagnetic radiation other than the current in the first conductive path. This can further improve the accuracy of the current sensor.

[0024] Further, according to some examples, the shielding material may form at least a portion of the electrical return from the first electrical terminal to the second electrical terminal, i.e., the shielding material may be a conductive material and form a portion of the conductive path between the first and second electrical terminals of the conductive winding to help enable the first and second electrical terminals to be positioned together.

[0025] The insulation distance from the obstacle is the minimum distance from the first end of the conductive winding (i.e., the first end of the shape formed by the conductive winding) to the obstacle. By locating the ends of the conductive winding in this manner, maximum magnetic flux and closest access to the current are achieved without being impeded by the obstacle, thereby improving the accuracy of the current sensor. The insulation distance from the first end to the obstacle may be equal to or different from the insulation distance from the second end to the obstacle.

[0026] The insulation distance can be used to isolate the conductive winding from an obstacle, for example, when the obstacle is a conductive part that may or may not have an electrical potential. Along the insulation distance, insulation that provides sufficient clearance and creepage distance is provided by at least one of the PCB material (i.e., the material from which the PCB is formed), air, and an insulating material (such as a conformal coating, plastic, rubber, or other insulator) disposed between the first conductive winding and the obstacle.

[0027] According to a second aspect, there is provided a method of incorporating a current sensor in a PCB for sensing a current through a first conductive path, the method comprising disposing a first conductive winding in an open configuration in a plane of the PCB, the open configuration having a first end and a second end and defining a sensing area in the plane of the PCB for sensing a current through the first conductive path disposed within the sensing area, the first conductive winding formed from a conductive portion having a plurality of turns extending across a thickness of the PCB, the first conductive winding being spaced from an obstacle by at least an insulation distance from the first end to the obstacle.

[0028] In some examples, the method further includes, prior to the placing, determining an insulation distance based at least in part on the magnitude of the current flowing through the first conductive path, the size of the obstacle, the potential difference between the first conductive winding and the obstacle, the potential difference between the first conductive winding and the first conductive path, the potential difference between the first conductive path and the obstacle, and / or the material that constitutes the insulating material (as described above).

[0029] In some examples, the current sensor may include an electronic integrator circuit or a signal processing module may be used instead, in which case the method may further comprise receiving a sensor signal from the current sensor and determining, by the signal processing module, a current measurement of the current based at least in part on the sensor signal.

[0030] According to a third aspect, a system is provided that includes a first current sensor, a second current sensor, and a signal processing module. The first current sensor is integrated into a first PCB and senses a first current flowing through a first conductive path, and the second current sensor is integrated into a second PCB and senses a second current flowing through a second conductive path. The current sensors are the same as or similar to those described above for the first or second aspects of the disclosure. A signal processing module is provided for processing sensor signals from the first and second current sensors. The signal processing module is configured to generate a current measurement of the first current based at least in part on the sensor signal from the second current sensor.

[0031] According to some examples, a first sensing area of ​​the first current sensor is arranged to collect a first magnetic flux induced by the first current, and a second sensing area of ​​the second current sensor is arranged to collect a second magnetic flux induced by the second current. Some of the magnetic flux originating from the second current may be collected by the first conductive winding and contribute to the total electromotive force (i.e., it may not cancel). In such examples, to improve the measurement accuracy, the signal output from the second current sensor may be taken into account when measuring the magnitude of the first current. The same applies to the effect of the first current on the second current sensor. In some examples, taking into account the signal output from the second sensor may comprise further considerations such as a known distance between the first and second currents, or an error in the first or second sensor signal.

[0032] Additionally or alternatively, the second current through the second conductive path may be controlled (i.e., included in the sensor signal) by a control signal, and the signal processing module may be further configured to generate a current measurement of the first current based at least in part on the control signal. The control signal may also be used when the second conductive path does not have a current sensor attached.

[0033] The two system concepts described in the above two paragraphs can be used independently or together to improve the accuracy of a current sensor.

[0034] Instead of attempting to shield the first current sensor from electromagnetic interference caused by the second current, the voltage signal induced therefrom may be factored in by a signal processing module to allow the current sensor to accurately compensate for the magnetic flux induced by the other current. This processing may factor in known characteristics of one or both currents, or signal processing methods may be applied to the voltage signal to remove contributions from currents other than those associated with a given current sensor.

[0035] However, although the terms "first" and "second" are used, the first obstacle and the second obstacle may be the same obstacle and / or the first PCB and the second PCB may be part of the same PCB.

[0036] As mentioned above, the conductive paths may be pins of an electronic device. For example, the first conductive path may be a pin of a first electronic device, and the second conductive path may be a pin of a second electronic device. And, if the first PCB and the second PCB are part of the same PCB, the first electronic device and the second electronic device may be electrically connected through the PCB.

[0037] In some examples, the first and second current sensors are arranged symmetrically. For example, the first and second PCBs may be arranged in parallel planes, and the first and second current sensors may be arranged symmetrically with respect to a plane parallel to the first and second PCBs. Alternatively, the first and second PCBs may be part of the same PCB, and the first and second current sensors may be arranged symmetrically with respect to a plane perpendicular to the PCB.

[0038] According to a fourth aspect, there is provided a motor converter for a drivetrain of a railway vehicle comprising one or more transistors, each having at least one pin, and at least one current sensor, the same as or similar to the current sensor described above, for sensing current through at least one pin of the one or more transistors.

[0039] One or more embodiments will now be described, by way of example only, with reference to the following drawings, which should not be understood as being to scale. [Brief description of the drawings]

[0040] [Figure 1A] FIG. 1A is a schematic perspective view of a current sensor integrated into a PCB, according to one embodiment of the present disclosure. [Figure 1B]FIG. 1B is a plan view of a PCB that illustrates the current sensor of FIG. 1A. [Figure 1C] FIG. 1C is a cross-sectional view of a PCB that illustrates a schematic configuration of the conductive windings of the current sensor of FIG. 1A. [Figure 1D] FIG. 1D is a cross-sectional view of a PCB that illustrates a schematic of another configuration of the conductive windings of the current sensor of FIG. 1A. [Diagram 2] FIG. 2 is a plan view of a PCB showing various open shapes (including arc shapes) in an example implementation. [Diagram 3] FIG. 3 is a plan view of a PCB showing the placement of various current sensors and obstacles in an exemplary implementation. [Figure 4] FIG. 4 is a plan view of a PCB showing the placement of various conductive paths and current sensors in an exemplary implementation. [Diagram 5] FIG. 5 is a schematic diagram illustrating a method for incorporating a current sensor into a PCB, according to one embodiment of the present disclosure. [Figure 6] FIG. 6 is a schematic diagram of a system including a current sensor and a signal processing module according to one embodiment of the present disclosure. [Figure 7] FIG. 7 is a schematic diagram of a motor converter for an electric railway drivetrain, according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] While the invention is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings detailed herein. It should be understood, however, that the detailed description herein and the drawings accompanying this specification are not intended to limit the invention to the particular forms disclosed. Rather, the intent is to cover all modifications, equivalents, and alternatives falling within the scope of the appended claims.

[0042] Any reference in this specification to prior art documents or comparative examples should not be considered as an admission that such prior art is widely known or forms part of the general knowledge common to the art.

[0043] As used herein, the words "comprises," "comprising," and similar words should not be construed in an exclusive or exhaustive sense. In other words, they are intended to mean "including, but not limited to."

[0044] The present invention will be described by a number of illustrated examples below. These examples are provided for illustration and illustration only and will not be construed as being intended to limit the scope of the present invention. Instead, the scope of the present invention should be defined by the appended claims. Furthermore, although examples are provided in the form of each embodiment, it will be recognized that the present invention also encompasses combinations of the embodiments described herein.

[0045] FIG. 1A is a schematic perspective view of a current sensor integrated into a printed circuit board (PCB) according to one embodiment.

[0046] 1A, a current sensor (generally designated 100) is shown incorporated into a PCB 102 having a thickness d. The current sensor 100 is positioned to sense a current 104 flowing through a conductive path 106. For ease of illustration, the conductive path 106 is shown as extending on both sides of the PCB 102, although the conductive path 106 may alternatively extend only across the thickness d of the PCB 102 or a portion thereof.

[0047] A conductive path 106 is shown proximate an obstacle 108 in the PCB 102. Like the conductive path 106, the obstacle 108 is shown as extending on both sides of the PCB 102, but instead, the obstacle 108 may extend only through a thickness d of the PCB 102 or a portion thereof. In essence, the obstacle 108 (which may be thought of as an obstruction, a hindrance, a blockage, etc.) constrains the spatial placement of the current sensor. However, the shape of the current sensor 100, and in particular its conductive winding 110, allows for measurement of the current flowing through the conductive path 106 despite the presence of the obstacle 108.

[0048] The obstruction 108 may be an inert or benign obstruction, such as a plastic mating screw in the PCB 102 or a mechanical obstruction such as a through hole in the PCB 102, thereby limiting the ability to mount the current sensor 100 in the vicinity of the obstruction 108.

[0049] The obstacle 108 may also be an additional conductive path (eg, an adjacent pin of an electronic device, or a connection or trace within the PCB 102 that may or may not carry current, etc.).

[0050] The current sensor 100 includes a conductive winding 110 that is visible in the drawings for illustrative purposes but may be obscured by one or more layers, shielding material, and / or certain other components or elements included in the PCB 102 above and / or below the current sensor. As described further below, the conductive winding is formed from a conductive portion having multiple turns that extend across the thickness d of the PCB (i.e., all or a portion of the thickness d).

[0051] As shown in FIG. 1A, the conductive windings 110 form an open shape 112 in the plane of the PCB 102 (i.e., the XY plane in the illustrated coordinate axes). The open shape 112 is shown as a solid line bounding the conductive windings 110, but this is purely for illustrative purposes and the outline may not be visible. That is, the open shape 112 is formed by the arrangement of the conductive windings 110. The open shape 112 in the example of FIG. 1A is an elliptical arc because the conductive windings 110 are arranged to form an elliptical arc around the conductive path 106. However, the open shape 112 may be any open shape, such as an arc, a circular arc, a U-shape (e.g., with a curved or flat bottom), a straight line, an open polygon such as an open square or octagon, or some other open shape, as described in more detail below. The open shape 112 may further be defined by an extension in the plane of the PCB 102 (ie, providing a width or thickness), such as in the case of an arc, to form a region of a ring when viewed from above or below.

[0052] The open shape 112 has a first end 114a and a second end 114b (the term "end" has no relation to the electrical terminals of the conductive portions that form the conductive winding 110). The open shape 112 does not have any intersecting line segments, and the open shape 112 does not begin and end at the same point. Thus, the first end 114a of the open shape 112 is in a different physical location on the PCB 102 than the second end 114b of the open shape 112, which is separated by the obstruction 108.

[0053] Advantageously, the conductive winding 110 forms an open shape 112 having an opening (defined by a spacing between a first end 114a and a second end 114b) that can be positioned to conform to an obstacle 108. As shown in FIG. 1A, the current sensor 100 (and in particular its conductive winding 110) is spaced from the obstacle 108 in the PCB 102 by at least an insulation distance 118 from the first end 114a to the obstacle 108.

[0054] This arrangement allows the conductive winding 110 of the current sensor 100 to be shaped for optimal magnetic flux collection, ease of assembly, minimal use of material, etc., while taking into account the spatial limitations imposed by the obstacle 108.

[0055] The open shape 112 formed by the conductive windings 110 defines a sensing region 116. The sensing region 116 is an area where magnetic flux generated by a current (e.g., current 104) flowing through the conductive path 106 can be reliably sensed to produce a measurement of the current flowing through the conductive path 106. Thus, the sensor is positioned in the PCB with the conductive path 106 located within the sensing region 116 such that the current 104 can be sensed by the current sensor 100.

[0056] Although the discussion herein is in the context of a plane (i.e., the XY plane) of the PCB 102, the sensing region 116 may be three-dimensional (3D). Thus, the sensing region 116 illustrated in FIG. 1A may be thought of as a cross-sectional view of this 3D shape projected onto the illustrated surface of the PCB 102. This is the same abstraction used when discussing the open shape 112 of the conductive winding 110. That is, the illustrated open shape 112 is a projection of the boundary of the conductive winding 110 (which may be thought of as an illustration of a shape along which an axis extending through the conductive winding 110 is located). However, the actual shape of the conductive winding 110 may be 3D in that it extends through the thickness d of the PCB 102.

[0057] Although the discussion herein is of an orthogonal arrangement (e.g., the conductive paths and obstacles are aligned with the Z-axis), it will be understood that the techniques disclosed herein are equally applicable to arrangements in which, for example, the conductive paths 106 or the obstacles 108 are not aligned with the Z-axis. In such cases, the insulation distance 118 may be determined from the closest approach of, for example, the obstacles 108 and the conductive windings 110 along the other direction.

[0058] 1B is a schematic diagram of the current sensor of FIG. 1A from above (i.e., the Z axis faces into the page), showing a plan view of the PCB. PCB 102 is not shown.

[0059] 1B, the insulation distance 118a between the first end 114a and the obstacle 108 is less than the insulation distance 118b from the second end 114b to the obstacle 108. However, the insulation distance 118a may be greater than or equal to the insulation distance 118b.

[0060] If there is some minimum spacing from obstacle 108 required for proper operation of current sensor 100, it may be advantageous to make insulation distance 118a equal to insulation distance 118b. In this manner, maximum proximity of conductive path 106 within open shape 112 of conductive winding 110 can be achieved, thus increasing the sensitivity, accuracy, and / or resistance of current sensor 100 to external interference.

[0061] Figure 1C is a cross-sectional view of a PCB that illustrates the current sensor of Figure 1A, taken through a portion of conductive winding 110 aligned in the Y direction (e.g., the rightmost portion in Figure 1B).

[0062] As mentioned above, the conductive winding 110 is formed from a conductive portion having a number of turns 120 that extend across the thickness d of the PCB 102. For illustration purposes, approximately five turns 120 are shown. However, the number of turns 120 may be in the range of 4 to 100 turns. Fewer turns 120 in the conductive winding 110 may enable a larger bandwidth and / or better frequency response of the current sensor 100, but there is less magnetic flux collection capability. An advantageous tradeoff of these factors may be achieved by using a number of turns 120 in the range of 8 to 32.

[0063] As mentioned above, turns 120 of conductive winding 110 surround a location (ie, a location in the XZ plane) to allow the passage of magnetic field lines therethrough.

[0064] 1C has four layers (each shown diagrammatically by a dotted line), although PCB 102 may have more or fewer layers. Turns 120 of conductive winding 110 extend from the second layer to the third layer of PCB 102 in this illustrated example (counting from the bottom up), and the conductive portion on which conductive winding 110 is formed has first electrical terminal 122a and second electrical terminal 122b.

[0065] Additionally, in the illustrated example, there is an electrical return loop 124 provided between the first and fourth layers of the PCB 102 such that the return to the second electrical terminal 122b is co-located with the first electrical terminal 122a. In some examples, these terminals 122a and 122b may be co-located at the first end 114a or the second end 114b of the conductive winding 110.

[0066] Also shown in FIG. 1C is a shielding material (shown as upper and lower shielding portions 126a and 126b, but generally referred to as shielding material 126 in the following text). The shielding material is provided to at least partially shield the conductive winding 110 from sources of electromagnetic radiation other than the current 104 in the conductive path 106. In the illustrated example, the shielding material 126 is disposed on the first and fourth layers of the PCB 102, i.e., the top and bottom layers of the PCB 102 as shown. However, it will be understood that other layers may be used. Furthermore, it will be understood that the shielding material 126 may additionally or alternatively be disposed to extend through a thickness d of the PCB 102 to provide shielding of the conductive winding 110 from other directions (e.g., along the X-axis).

[0067] The shielding material 126 may be a conductive material and may be thought of as a "screen" that blocks electromagnetic interference that may otherwise cause fluctuations in the conductive winding 110, for example resulting in inaccuracies in current measurements from the current sensor 100. To aid in the shielding / screening capabilities of the shielding material 126, portions 126a and 126b of the shielding material 126 may be electrically connected to each other and / or to a ground connection 128.

[0068] In some examples, as shown, the shielding material 126 may form at least a portion of the electrical return from the first electrical terminal 122a to the second electrical terminal 122b. This can advantageously allow the current sensor to be mounted on a PCB 102 having fewer layers while retaining improved resistance to external electromagnetic interference. In such examples, the shielding material 126 may advantageously be electrically conductive and formed from the same conductive portion as the conductive winding 110.

[0069] Figure 1D illustrates an alternative configuration of the conductive winding 110 of Figure 1A, where a return loop 124 is formed along a similar path as the initial loop of the conductive winding 110. The return loop 124 illustrated in Figures 1C and 1D cancels the magnetic field (interference) in the Z direction, and the configuration illustrated in Figure 1D may achieve further reduction in spatial footprint (e.g., layers and / or thickness) in the PCB 102.

[0070] FIG. 2 is a plan view of a PCB 102 showing various open shapes 112 in an example implementation.

[0071] As mentioned above, the open shape 112 of the conductive winding 110 may be thought of as a spatial boundary of its arrangement on the PCB 102, when viewed from a projection onto the plane of the PCB 102 (i.e., from above the PCB or from below the PCB). Thus, the open shape 112 illustrated in FIG. 2 may not be a component, but instead may represent a general arrangement of the conductive winding 110 in the plane of the PCB 102.

[0072] A first example of an open shape 112 is arc 112a, which is an elliptical arc. Arc 112a may alternatively be a circular arc. Ideal magnetic field lines emanating from a current-carrying conductive path have a circular path. Thus, a circular arc can advantageously collect a larger amount of magnetic flux, for example from a concentrically arranged conductive path (such as conductive path 106) having a current (such as current 104) flowing therethrough.

[0073] A further example of an open shape 112 is an L-shape 112b, which can be thought of as two straight lines joined at an angle (i.e., a right angle or some other angle). Alternatively, the open shape 112 can be a U-shape 112c, which can be thought of as three straight lines joined at an angle, for example with a flat bottom. An extension of this concept can be a rectangular box shape (i.e., an open rectangle, which is an example of an open polygon) with portions removed from it to form the open shape 112. Alternatively, some or all of these lines can be curved.

[0074] The open shape 112 may alternatively be formed from a line 112d or two lines 112d (which, when placed in parallel, form an "equals" arrangement). The lines 112d may be individually connected to an integrating circuit and / or electrically connected to each other by connecting lines or wires (shown by dotted lines) to form a single current sensor.

[0075] Arranging the conductive windings 110 in a shape that includes straight lines can substantially simplify the construction of the current sensor 110. It can also simplify the construction of right angles coupling angles between the straight lines.

[0076] Although conductive winding 110 is shown to be of generally uniform width, space constraints, construction considerations, or other motivations may dictate a need to vary the width (i.e., vary the size of the turns along the length of conductive winding 110).

[0077] FIG. 3 is a plan view of a PCB 102 showing various arrangements of current sensors 100a-g, conductive paths 106 and obstacles 108 in an example implementation.

[0078] For purposes of illustration, current sensors 100a-g are represented by open shapes defined by their conductive windings in an arc in this example.

[0079] The current sensor 100a is positioned to at least partially surround or encircle the conductive path 106, although the size or shape of the sensing area defined by the shape of the conductive windings may not require this, as long as the conductive path 106 is positioned such that the magnetic field lines originating from the current 104 pass through it. The current sensor 100a is in close proximity to an obstacle 108. The opening of the current sensor 100a is positioned such that the first and second ends of the open shape have equal insulation distances from the obstacle 108 to which they are adjacent. It can be seen in FIG. 3 that the open shape advantageously avoids the obstacle 108.

[0080] The current sensors 100b and 100c are arranged symmetrically in the plane of the PCB 102. Additionally, the current sensors 100a and 100d are arranged symmetrically in the plane of the PCB 102.

[0081] Additionally, current sensors 100d and 100e are positioned symmetrically in the plane of PCB 102 and are arranged to measure currents flowing through different conductive paths 106, while having identical obstacles 108 in close proximity thereto.

[0082] Additionally, current sensors 100f and 100g are symmetrically positioned in the plane of PCB 102 and are positioned to measure current flowing through the same conductive path 106 while being mutually adjacent to two obstacles 108. Thus, although the obstacles 108 adjacent to current sensors 100f and 100g prevent the mounting of a current sensor 100 having a complete or surrounding shape, multiple current sensors (e.g., 100f and 100g) can be positioned to individually measure the same current flowing through conductive path 106.

[0083] Symmetry in the plane of the PCB 102 may be interpreted to include planes of symmetry along any of the X, Y, and Z directions, for example, as defined in the previous figures. Additionally, although the current sensors 100a-g are shown as all mounted / located on the same PCB 102, the current sensors 100a-g may instead be mounted / located on separate PCBs, for example, that are at least spatially fixed relative to one another.

[0084] A symmetrical arrangement of current sensors (i.e., the shape of the conductive windings is substantially symmetrical in a plane parallel or perpendicular to the plane of the PCB) allows for a predictable or balanced effect of magnetic flux from a conductive path passing through one current sensor on the magnetic flux from a conductive path passing through another current sensor, so that interference from other currents can be easily added to or subtracted from the measured current signal / magnitude.

[0085] In some examples, a first sensing area of ​​a first current sensor (e.g., 100a) is positioned to collect a first magnetic flux induced by a first current, and a second sensing area of ​​a second current sensor (e.g., 100d) is positioned to collect the first magnetic flux, and a signal processing module may be used to process signals from both current sensors 100a and 100d to generate a quantity / signal value of the current flowing through the conductive path associated with current sensor 100a, and vice versa.

[0086] According to a further example, the first current flowing through the first conductive path 106 may be controlled according to a control signal. For example, the first conductive path may be a pin of a semiconductor transistor. This represents an exemplary situation in which a semiconductor transistor is used as a switch controlled by a voltage on a gate pin. In such a case, it is advantageous to measure the current flowing through the main current carrying pin of the transistor (drain, source, collector, emitter, or the like depending on the type of transistor) so that the resulting current from the switching of the semiconductor transistor can be measured.

[0087] In this example, a control signal may be provided to the signal processing module such that the signal processing module is further configured to generate a current measurement of a second current (e.g., a pin of an adjacent transistor switch) based at least in part on the control signal for the first current. For example, magnetic interference of nearby currents may be estimated based at least on the control signal, or taking a current measurement of the second current may be timed when the control signal indicates that the first current is off (i.e., no current is flowing in the first conductive path), such that the current measurement is expected to be free of electromagnetic interference.

[0088] Also, the current sensor can be placed close to the conductive path 106 in the hopes of generating an interfering magnetic field that will reduce interference therefrom, thereby reducing the need for shielding materials or other techniques to reduce interference (e.g., signal processing).

[0089] FIG. 4 is a plan view of a PCB (not shown) showing the placement of various AC conductive paths and current sensors (again represented as arc shapes) in an exemplary implementation.

[0090] The open (arc) shape of the current sensor has a first end and a second end as described above. The first and second ends define an axis of opening 130a passing through the first and second ends and a midpoint on axis 130a between the first and second ends. Also shown is axis 130b perpendicular to axis of opening 130a and passing through the midpoint.

[0091] Three exemplary conductive paths A, B, and C (into the page) are shown, with the dotted lines being their resulting magnetic fields. Path A is substantially aligned with axis 130b, path B is substantially aligned with axis 130a, and path C is somewhere in between.

[0092] As shown in FIG. 4, all of the magnetic field lines from A (labeled A) enter the conductive winding (i.e., from below) and exit the conductive winding (i.e., at the top), so the electromotive force contribution from conductive path A is cancelled.

[0093] The majority of the magnetic field lines from B (labeled B) cross the conductive winding only once and therefore do not cancel the contribution from conductive path B.

[0094] Path C is somewhere between A and B, but some magnetic field lines (e.g., C1) appear to cancel while others (e.g., C2) do not. Thus, an advantageous placement of the current sensor aperture relative to a vicinity of a current-carrying path is along an axis located approximately halfway between the ends of the aperture, i.e., the first and second ends are located relative to the vicinity of path A such that axis 130b, perpendicular to the axis 130a of the aperture and passing through the midpoint, coincides with the location of path A.

[0095] FIG. 5 is a schematic diagram illustrating a method 500 for incorporating a current sensor into a PCB, in accordance with an embodiment of the present invention.

[0096] The method 500 includes placing a first conductive winding in an open configuration in a plane of a PCB, as represented by block 510 .

[0097] According to the method 500, the open shape has a first end and a second end and defines a sensing area in a plane of the PCB for sensing current through a first conductive path disposed within the sensing area, and a first conductive winding is formed from a conductive portion having a plurality of turns extending across a thickness of the PCB, the first conductive winding being spaced from an obstacle within the PCB by at least an insulation distance from the first end to the obstacle.

[0098] Method 500 may further include determining an insulation distance prior to the placing, for example with a view to minimizing the insulation distance and / or maximizing the ability of the current sensor to collect magnetic flux emanating from the current.

[0099] The decision may be based on the magnitude of the current flowing in the conductive path, since, for example, this may affect how far from the conductive path the conductive winding can still sense the magnetic field emanating therefrom (i.e., the overlap of the sensing area with the conductive path).

[0100] The determination of the insulation distance may be based on the size of the obstacle, which may affect the mechanical limitations of the installation (mounting / embedding) of the conductive winding in, for example, a PCB, and further, if the obstacle is a conductive path, the size (i.e., size or shape) may affect its electromagnetic properties.

[0101] The determination may additionally or alternatively be based on a potential difference between the first conductive winding and the obstacle, as this may affect, for example, the tendency for electrical arcing between the conductive winding and the obstacle.

[0102] The determination may additionally or alternatively be based on a potential difference between the first conductive winding and the first conductive path, since this may affect, for example, the tendency for electrical arcing between the conductive winding and the conductive path.

[0103] The determination may additionally or alternatively be based on a potential difference between the first conductive path and the obstacle, as this may affect, for example, the tendency for electrical arcing between the conductive path and the obstacle.

[0104] Additionally or alternatively, the determination of the insulation may be based on the material that constitutes the insulation material. For example, if the insulation material (i.e., the material that provides the insulation along the insulation distance) has good insulating properties, the insulation distance can be reduced. This allows the current sensors to be even more closely packed in their configuration.

[0105] FIG. 6 is a schematic diagram of a system 600 including current sensors 100L and 100R and a signal processing module 134, according to one embodiment.

[0106] As shown in Fig. 6, there is a first current sensor 100L integrated into the first PCB 102a and detecting a first current through the first conductive path 106a located adjacent to the first obstacle 108a. This current sensor 100L may be the same or similar as described above. The system 600 further comprises a second current sensor 100R integrated into the second PCB 102b and detecting a second current through the second conductive path 106b located adjacent to the second obstacle 108b. Fig. 6 is not intended to show the physical layout of the PCBs 102a and 102b, as the physical layout may be general as described above with reference to Fig. 3.

[0107] The first current sensor 100L outputs a first sensor signal represented by block 132a, and the second current sensor 100R outputs a second sensor signal represented by block 132b.

[0108] The illustrated system further includes a signal processing module 134 that processes the sensor signals 132a and 132b from the first and second current sensors 100L and 100R.

[0109] The signal processing module 134 is configured to generate a current measurement of the first current (i.e., the current through the conductive path 106a) based at least in part on the sensor signal from the second current sensor 100R. Thus, magnetic flux emanating from the first conductive path 106a may be collected by the conductive windings of the first current sensor 100L and the second current sensor 100R and used to contribute to the current measurement of the current through the first conductive path 106a generated by the signal processing module 134. In general, the current sensor 100R may be one or more current sensors, all controlled according to a known control signal. The first current (i.e., the current through the first conductive path 106a) may be based at least in part on the sensor signal from one or more of these current sensors exemplified by the current sensor 100R.

[0110] In some examples, a known control signal may be used in generating the current measurement of the first current. That is, the control signal of the second current flowing through the second conductive path 106b may indicate that the second current has paused, which may be used to ensure that the current in the first conductive path 106a measured from the first current sensor 100L is not unduly influenced by the contribution from the current flowing through the adjacent 106b. In a similar manner, the contribution from the second current may be estimated based on the control signal and therefore taken into account by the signal processing module 134 in generating the current measurement of the first current.

[0111] FIG. 7 is a schematic diagram of a motor converter 136 for an electric railway driveline, according to one embodiment.

[0112] Motor converter 136 may, for example, have a transistor 138 that controls the operation of motor converter 136. Transistor 138 has a pin 140 with a current sensor 100 that is the same as or similar to the current sensor described in the above description and that is positioned to sense the current flowing through pin 140 of transistor 138.

[0113] The transistor 138 may have pins such as a drain or source pin (or collector, emitter, or the like depending on the type of transistor). As an example, the current sensor 100 may measure the current flowing through the drain pin (and as described above is a conductive path), and thus the source pin may be considered as an obstacle in the sense of the obstacle 108 described in the above description. Thus, the current sensor 100 may be positioned to measure the current flowing through the drain pin 140 (which carries the main current of the transistor 138), as well as being spaced apart from the other pins of the transistor 138.

[0114] As transistors are packed closer together as technology advances, the present invention can advantageously provide measurement of current in increasingly dense electronic environments while maintaining the advantages of high accuracy, high bandwidth, and immunity to interference discussed above.

[0115] Unless expressly stated, it will be understood that examples shown in different drawings may be combined and that elements having like reference numbers in different drawings may be identical or similar to each other. In no event shall the above description be construed as limiting the scope of the invention, which is intended to be defined solely by the scope of the following claims.

Claims

1. A current sensor incorporated in a printed circuit board (PCB) for detecting a current flowing through a first conductive path, comprising a first conductive winding forming an open shape in a plane of the PCB, the open shape having a first end and a second end, defining a detection region in the plane of the PCB for detecting the current flowing through the first conductive path disposed within the detection region, the first conductive winding being formed from a conductive portion having a plurality of turns extending across the thickness of the PCB, the first conductive winding being spaced apart from an obstacle within the PCB by at least a distance from the first end to the obstacle, a current sensor.

2. The current sensor according to claim 1, wherein the open shape is an elliptical arc, an arc, an arc having a U-shape, or an open polygon.

3. The current sensor according to claim 1, wherein the distance from the first end to the obstacle is equal to the distance from the second end to the obstacle.

4. An insulating portion along the distance from the first end to the obstacle is disposed between the first conductive winding and the obstacle of a PCB material, air, and an insulating material provided by at least one of, the current sensor according to claim 1.

5. The current sensor according to claim 1, wherein the plurality of turns comprises turns within a range of 4 to 100.

6. The current sensor according to claim 1, wherein the plurality of turns comprises turns within a range of 8 to 32.

7. The current sensor according to claim 1, wherein the first conductive winding is electrically connected to an integrating circuit that generates an output voltage signal indicative of the current within the first conductive path.

8. The obstacle is a second conductive path having a potential different from that of the first conductive path, The distance from the first end to the obstacle corresponds to the distance from the second conductive path in order to suppress electrical interference between the second conductive path and the first conductive winding. The current sensor according to claim 1.

9. The first end and the second end define an axis of opening passing through the first end and the second end, and a midpoint on the axis between the first end and the second end, The first end and the second end are arranged with respect to the second conductive path such that an axis perpendicular to the axis of opening and passing through the midpoint coincides with the position of the second conductive path. The current sensor according to claim 8.

10. The conductive part includes a first electrical terminal and a second electrical terminal, The first electrical terminal and the second electrical terminal are arranged together at the first end or the second end. The current sensor according to claim 1.

11. The current sensor according to claim 1, further comprising a shielding material arranged to at least partially shield the first conductive winding from electromagnetic radiation sources other than the current in the first conductive path.

12. The shielding material forms at least a part of an electrical return from the first electrical terminal to the second electrical terminal. The current sensor according to claims 10 and 11.

13. The first conductive path consists of a pin of an electronic device. The current sensor according to claim 1.

14. The electronic device is a semiconductor transistor, The semiconductor transistor is any one of a silicon transistor, a silicon carbide transistor, or a high-power semiconductor transistor. The current sensor according to claim 13.

15. A method of incorporating a current sensor for detecting a current flowing through a first conductive path into a printed circuit board (PCB), comprising: arranging a first conductive winding in an open shape on a plane of the PCB; The open shape has a first end and a second end, and is a detection region on the plane of the PCB for detecting the current flowing through the first conductive path arranged in the detection region, defining a detection region; The first conductive winding is formed of a conductive portion having a plurality of turns extending over the thickness of the PCB; The first conductive winding is spaced apart from an obstacle in the PCB by at least a distance from the first end to the obstacle.

16. Before the arranging, the magnitude of the current flowing through the first conductive path, the size of the obstacle, the potential difference between the first conductive winding and the obstacle, the potential difference between the first conductive winding and the first conductive path, the potential difference between the first conductive path and the obstacle, and / or the material constituting the insulating material The method according to claim 15, further comprising determining an insulation distance based on at least a part of the above.

17. receiving a sensor signal from the current sensor; measuring a current measurement value of the current based on at least a part of the sensor signal by a signal processing module; The method according to claim 15 or 16, further comprising the above.

18. A first current sensor incorporated in a first printed circuit board (PCB) for detecting a first current flowing through a first conductive path; A second current sensor incorporated in a second PCB for detecting a second current flowing through a second conductive path; A signal processing module that processes sensor signals from the first current sensor and the second current sensor; and is provided with; Each of the first current sensor and the second current sensor is the current sensor according to claim 1; The signal processing module is a system configured to generate a current measurement value of the first current based on at least a part of the sensor signal from the second current sensor.

19. The first detection region of the first current sensor is arranged to collect a first magnetic flux induced by the first current and a second magnetic flux induced by the second current, according to the system of claim 18.

20. The second current flowing through the second conductive path is controlled by a control signal; The signal processing module is further configured to generate a current measurement value of the first current based on at least a part of the control signal, according to the system of claim 19.

21. The first obstacle and the second obstacle are the same obstacle, according to the system of claim 18.

22. The first PCB and the second PCB are parts of the same PCB, according to the system of claim 18.

23. The first conductive path is a pin of a first electronic device; The second conductive path is a pin of a second electronic device; The first electronic device and the second electronic device are parts of the same electrical circuit on the PCB, according to the system of claim 22.

24. The first current sensor and the second current sensor are arranged symmetrically, according to the system of claim 18.

25. The first PCB and the second PCB are arranged in parallel planes, and the first current sensor and the second current sensor are arranged symmetrically with respect to a plane parallel to the first PCB and the second PCB, or the first PCB and the second PCB are part of the same PCB, and the first current sensor and the second current sensor are arranged symmetrically with respect to a plane perpendicular to the PCB, the system according to claim 24.

26. A motor converter for a drive system of a railway vehicle, one or more transistors each having at least one pin, at least one current sensor according to claim 1 for detecting a current flowing through the at least one pin of the one or more transistors, A motor converter comprising.

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