Electrical system and current sensing system

Abstract

The invention discloses an electrical system and a current sensing system. The current sensing system includes: a first sensing point mounted on a left side of a width center line; the second sensing point is mounted on the right side of the width center line; and an operational amplifier. The first sensing point and the second sensing point both measure a magnetic field generated by current flowing through the copper bar in the z-axis direction, and the operational amplifier amplifies the difference value between the output of the first sensing point and the output of the second sensing point to generate an amplified signal. The electrical system and the current sensing system do not need a heavy magnetic core, so that the cost is reduced.

Description

Technical Field

[0001] This invention relates to a sensor, and more specifically, to an electrical system and a current sensing system. Background Technology

[0002] Magnetic sensors are used in a variety of applications. One such application is in the field of current sensors. By sensing (inducing and detecting) current using a magnetic sensor, the primary circuit (i.e., the conductor through which the measured current flows) can be electrically decoupled from the secondary circuit that carries the measurement signal and transmits it to the control circuit. In the range of 100 amperes and above, the conductor used is typically a solid metal bar with a rectangular cross-section, usually copper, often referred to as a "busbar". Because busbars optimize conductivity and weight, they are widely used in applications such as electric vehicles to deliver current to the motor.

[0003] The current flowing through the copper busbar is typically sensed by a sensor that measures the magnetic field within the gaps in the soft ferromagnetic elements surrounding the conductor. Figure 1 The sensing system 100 equipped with a magnetic core shown is widely used. For example... Figure 1 As shown, a current-carrying copper busbar 101 is surrounded by a magnetic core 102, which has a gap 103. The magnetic core 102 concentrates the magnetic field generated by the current flowing through the copper busbar into the gap 103. A sensor 104 is placed at the gap 103 to measure the magnetic field, thereby sensing the current flowing through the copper busbar. The sensed signal is amplified by an amplifier 105 before being transmitted to the control circuit.

[0004] However, the large size of this magnetic core increases manufacturing costs and weight, which are critical for electric vehicles. Furthermore, the core limits the bandwidth of current measurement and exhibits hysteresis, introducing errors at low currents.

[0005] Some existing techniques attempt to provide a coreless solution by incorporating notches in the copper busbar. However, these notches increase resistance, thereby increasing Joule heating within the copper busbar. Summary of the Invention

[0006] According to an embodiment of the present invention, an electrical system is provided, comprising: a copper busbar carrying current, the copper busbar having an opening located at the middle position of the copper busbar; a current sensing system installed at the opening of the copper busbar to measure the current flowing through the copper busbar; wherein the current sensing system comprises: a first sensing point installed to the left of a width centerline, the width centerline being defined as the z-axis, the first sensing point measuring a magnetic field generated along the z-axis direction by the current flowing through the copper busbar; a second sensing point installed to the right of the width centerline, the second sensing point measuring a magnetic field along the z-axis direction by the current flowing through the copper busbar; an operational amplifier amplifying the difference between the output of the first sensing point and the output of the second sensing point to generate an amplified signal; wherein the width centerline is a line passing through the center of the copper busbar along the thickness direction of the copper busbar.

[0007] According to an embodiment of the present invention, a current sensing system is also provided, installed at the opening of a copper busbar. The current sensing system includes: a first sensing point installed to the left of the width centerline, the width centerline being set as the z-axis of a coordinate system, the first sensing point measuring the magnetic field generated by the current flowing through the copper busbar along the z-axis; a second sensing point installed to the right of the width centerline, the second sensing point measuring the magnetic field generated by the current flowing through the copper busbar along the z-axis; and an operational amplifier amplifying the difference between the output of the first sensing point and the output of the second sensing point to generate an amplified signal; wherein the distances of the first sensing point and the second sensing point from the width centerline are substantially equal.

[0008] According to an embodiment of the present invention, a current sensing system is also proposed, installed at an opening in a copper busbar, the opening being located in the middle of the copper busbar. The current sensing system includes: at least one row of sensors, each row including at least two sensors distributed along the x-axis, the sensors measuring the magnetic field along the z-axis generated by the current flowing through the copper busbar; and an operational amplifier amplifying the difference between the outputs of all sensors to generate an amplified signal; wherein the x-axis is the thickness centerline passing through the center of the copper busbar along the width direction, and the z-axis is the width centerline passing through the center of the copper busbar along the thickness direction.

[0009] According to the above-described electrical system and current sensing system of various aspects of the present invention, bulky magnetic cores are not required, thus reducing costs. Attached Figure Description

[0010] Figure 1 A conventional sensing system 100 equipped with a magnetic core is shown schematically.

[0011] Figure 2 This is a schematic diagram of a copper busbar carrying a target current according to an embodiment of the present invention;

[0012] Figure 3 A schematic cross-sectional view of a copper busbar cut along the CP line according to an embodiment of the present invention is shown.

[0013] Figure 4 A current sensing system 400 installed at an opening in a copper busbar is schematically shown according to an embodiment of the present invention.

[0014] Figure 5 A current sensing system 500 installed at an opening in a copper busbar is schematically shown according to an embodiment of the present invention.

[0015] Figure 6 The magnetic flux lines are schematically shown when the target current flows through the copper busbar during system operation;

[0016] Figure 7 A current sensing system 700 installed at an opening in a copper busbar is schematically shown according to an embodiment of the present invention.

[0017] Figure 8 The diagram schematically illustrates the outer packaging of a sensor when it is mechanically attached to a copper busbar according to an embodiment of the present invention.

[0018] Figure 9 A current sensing system 900 installed at an opening in a copper busbar is schematically shown according to an embodiment of the present invention.

[0019] Figure 10 A current sensing system 1000 installed at an opening in a copper busbar is schematically shown according to an embodiment of the present invention. Detailed Implementation

[0020] Specific embodiments of the present invention will now be described in detail. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other instances, well-known circuits, materials, or methods have not been specifically described to avoid obscuring the invention.

[0021] Throughout this specification, references to “an embodiment,” “an example,” or “an example” mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases “in an embodiment,” “in an embodiment,” “an example,” or “an example” appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the accompanying drawings provided herein are for illustrative purposes and are not necessarily drawn to scale. It should be understood that when an element is referred to as “coupled to” or “connected to” another element, it can be directly coupled to or coupled to the other element, or there may be intermediate elements. Conversely, when an element is referred to as “directly coupled to” or “directly connected to” another element, there are no intermediate elements. The same reference numerals indicate the same elements. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Figure 2 This is a schematic diagram of a copper busbar carrying a target current according to an embodiment of the present invention. The target current is the current that needs to be measured and transmitted to subsequent stages of the circuit for further electrical control. Figure 2 As shown, a through-hole is located approximately at the center of the copper busbar along its width. The copper busbar includes conductors carrying a target current, which typically has a relatively high current value, such as tens of amperes. In one embodiment of the invention, the copper busbar is made of copper.

[0023] The opening can be circular, slotted, or rectangular. In one embodiment of the invention, the shape and size of the opening depend on the ease of manufacturing, the amplitude of the signal, and the allowable variation due to misalignment. A current sensor can be mounted on the opening with appropriate settings, which will be described in detail below by cross-sectional views along the CP line.

[0024] Figure 3 A schematic cross-sectional view of a copper busbar cut along the CP line according to an embodiment of the present invention is shown. For clarity of description, Figure 3 A coordinate system is established, with its reference point (i.e., the zero point) at the intersection of the thickness centerline (MTL) and the width centerline (MWL). The thickness centerline (MTL) is a line passing through the center of the copper busbar along its width direction, and this line is set as the x-axis of the coordinate system. The width centerline is a line passing through the center of the opening along the thickness direction of the copper busbar, and this line is set as the z-axis of the coordinate system. In one embodiment of the invention, the y-axis is along the length of the copper busbar (i.e., along the length of the opening).

[0025] In one embodiment of the invention, the xz plane is a sensing (detecting and sensing) plane. The x-axis is parallel to the x-direction; the z-axis is parallel to the z-axis direction.

[0026] Figure 4 A current sensing system 400, installed at an opening in a copper busbar according to an embodiment of the present invention, is schematically shown. Figure 4 In the example, the current sensing system includes: a first sensing point 11, mounted to the left of the width midline MWL; a second sensing point 12, mounted to the right of the width midline MWL; and an operational amplifier (also called a differential amplifier) ​​13. The first sensing point 11 and the second sensing point 12 are positioned along the x-direction and have substantially equal distances from the width midline MWL (e.g., as shown in the image). Figure 4 The distances between the first sensing point 11 and the second sensing point 12 and the width midline MWL shown are +r and -r, respectively.

[0027] The first sensing point 11 and the second sensing point 12 respectively measure the magnetic field generated by the target current flowing through the copper busbar in the z-axis direction. Then, the outputs of the first sensing point 11 and the second sensing point 12 are passed to the operational amplifier 13. The operational amplifier 13 is used to amplify the difference between the outputs of the first sensing point 11 and the second sensing point 12 to generate an amplified signal AMP.

[0028] In one embodiment of the invention, each of the first sensing point 11 and the second sensing point 12 may include a half-bridge, such as two sensors connected in series between a power supply and a reference ground, e.g. Figure 4 As shown. In another embodiment of the invention, the first sensing point 11 and the second sensing point 12 may each include a single sensor, such as... Figure 5 As shown. The sensor can include a linear sensor with the sensing direction along the z-axis. The linear sensor can include a vertical Hall effect sensor measuring the field in the sensor plane or a tunneling magnetoresistive (TMR) sensor measuring an in-plane field. If the application has low noise requirements, a TMR sensor may be preferred.

[0029] Figure 6 The diagram schematically illustrates the magnetic flux lines as the target current flows through the copper busbars during system operation. The space within the opening can be considered as the gap between two nearby copper busbars. Therefore, the magnetic flux lines change direction along the z-axis at the center point of the opening. Figure 6 As shown, one direction is downward, represented by B1, while the other direction is upward, represented by B2.

[0030] Since the distance between the two sensing points is much greater than the distance between any sensing point (11 or 12) and the adjacent conductor carrying the current, the magnetic field generated by the adjacent conductor is almost the same at both sensing points and can be considered substantially uniform. The uniform magnetic field has the same effect at both sensing points. Because the output of operational amplifier 13 is the difference between the outputs of the first sensing point 11 and the second sensing point 12, the uniform external magnetic field cancels out, meaning it has no effect on the output of operational amplifier 13.

[0031] For the magnetic field generated by the target current flowing through the copper busbar, since the distances of the first sensing point 11 and the second sensing point 12 along the x-direction to the width midline MWL are approximately equal, the influence of the magnetic field on the first sensing point 11 and the second half-bridge 12 along the x-direction is canceled out. Similarly, the influence of the magnetic field on the first sensing point 11 and the second half-bridge 12 along the y-direction is also canceled out. However, since the magnetic fields along the z-axis are opposite to each other, their influence on the first sensing point 11 and the second sensing point 12 along the z-axis is also opposite to each other. Therefore, the amplified signal AMP, which characterizes the difference between the outputs of the first sensing point 11 and the second sensing point 12, is proportional to the target current flowing through the copper busbar.

[0032] Therefore, the current sensing systems 400 and / or 500 effectively measure the current near the opening; and the output of the operational amplifier (i.e., the output of the current sensing system) is substantially proportional to the current density.

[0033] Therefore, by properly setting an opening on the copper busbar and placing the sensor appropriately, the current flowing through the copper busbar can be measured well without the need for a bulky magnetic core.

[0034] Figure 7 A current sensing system 700 installed at an opening in a copper busbar is schematically shown according to an embodiment of the present invention. Figure 7 The current sensing system 700 in the middle and Figure 4 The current sensing system in the middle is similar to the 400, except that in Figure 7 In the example, both the first sensing point 11 and the second sensing point 12 are placed far away from the thickness midline MTL, and their distances (h) from the thickness midline MTL are approximately equal.

[0035] In the z-axis direction, since the magnetic field is maximum at the thickness midline, the movement of the sensor along the z-axis will increase the magnetic field at one sensing point and decrease it at another. Therefore, the first-order gain change is canceled out.

[0036] When the current sensing system is mechanically attached to the copper busbar, the current sensing system has a cylindrical outer casing (or "probe") for essentially filling the opening, and the current sensing system has a larger head as a stopper, such as... Figure 8As shown. It can be threaded at the other end to securely attach to the copper busbar. In one embodiment of the invention, the sensor's outer casing may be equipped with side pins to ensure that the sensor within the opening is aligned with the current direction. This output enclosure prevents any relative movement of the sensor relative to the copper busbar, ensuring that the amplified signal AMP remains unchanged during product use. In another embodiment of the invention, the probe is inserted into the opening and then overmolded together with the connector to form a copper busbar current sensor module.

[0037] Figure 9 A current sensing system 900, installed at an opening in a copper busbar according to an embodiment of the present invention, is schematically shown. Figure 9 In the example, the current sensing system 900 includes at least one row of sensors 14, each row including at least two sensors distributed along the x-axis. The sensors measure the magnetic field along the z-axis generated by the current flowing through the copper busbar. The current sensing system 900 also includes an operational amplifier 13 for amplifying the difference between the outputs of all the sensors to generate an amplified signal AMP.

[0038] In one embodiment of the invention, all sensors are integrated on the same chip.

[0039] Figure 9 The example shown illustrates a three-row sensor configuration. However, those skilled in the art will recognize that other numbers of rows of sensors are also suitable for measuring the magnetic field along the z-axis and for compensating for misalignments along the z-axis.

[0040] In one embodiment of the invention, the three rows of sensors are placed with the thickness midline MTL as the center.

[0041] In one embodiment of the invention, the sensor includes a vertical Hall effect sensor that measures the in-plane magnetic field generated by the current flowing through the copper busbar. The current sensing system 900 further includes a Hall bias current block 15 that provides a bias current to the sensor such that the vertical Hall effect sensor is properly biased and generates the desired signal to the operational amplifier 13.

[0042] Figure 10 A current sensing system 1000 installed at an opening in a copper busbar is schematically shown according to an embodiment of the present invention. Figure 10 The current sensing system 1000 in Figure 4 The current sensing system in the middle is similar to the 400, except that in Figure 10 In the example, the current sensing system 100 further includes a first small magnetic core (21), a second small magnetic core (22), a third small magnetic core (23) and a fourth small magnetic core (24) located at each corner of the sensing plane, respectively, to concentrate the magnetic flux into the sensing plane.

[0043] In one embodiment of the invention, the magnetic core may be made of a soft ferromagnetic material with high permeability.

[0044] Although the invention has been described with reference to several exemplary embodiments, it should be understood that the terminology used is descriptive and exemplary, and not restrictive. Since the invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. An electrical system comprising: A copper busbar carrying current, the copper busbar having an opening located at the middle position of the copper busbar; A current sensing system is installed at the opening of the copper busbar to measure the current flowing through the copper busbar; The current sensing system includes: A first sensing point is installed to the left of the width centerline, which is set as the z-axis. The first sensing point measures the magnetic field generated by the current flowing through the copper busbar along the z-axis direction. The second sensing point is installed on the right side of the width centerline. The second sensing point measures the magnetic field along the z-axis generated by the current flowing through the copper busbar. An operational amplifier amplifies the difference between the outputs of the first sensing point and the second sensing point to generate an amplified signal; wherein The width centerline is a line that passes through the center of the copper busbar along the thickness direction.

2. The electrical system as claimed in claim 1, wherein: The first and second sensing points are placed along the thickness midline, and the distances of both from the width midline are approximately equal. The thickness centerline is a line passing through the center of the copper busbar along the width direction, and the thickness centerline is set as the x-axis.

3. The electrical system as claimed in claim 1, wherein: The first and second sensing points are placed far from the thickness centerline, and both are approximately equidistant from the thickness centerline. The thickness centerline is a line passing through the center of the copper busbar along the width direction, and the thickness centerline is set as the x-axis.

4. The electrical system as described in claim 2 or 3, further comprising: The first, second, third, and fourth small magnetic cores are located at the four corners of the sensing plane, respectively, and the x-axis and z-axis form the sensing plane.

5. A current sensing system installed at an opening in a copper busbar, the current sensing system comprising: The first sensing point is installed to the left of the width centerline, which is set as the z-axis of the coordinate system. The first sensing point measures the magnetic field along the z-axis generated by the current flowing through the copper busbar. The second sensing point is installed on the right side of the width centerline. The second sensing point measures the magnetic field along the z-axis generated by the current flowing through the copper busbar. An operational amplifier amplifies the difference between the output of the first sensing point and the output of the second sensing point to generate an amplified signal; in The distances between the first sensing point and the second sensing point and the width midline are approximately equal.

6. The current sensing system as claimed in claim 5, wherein: The width centerline is a line that passes through the center of the copper busbar along the thickness direction; The thickness centerline is a line that passes through the center of the copper busbar along the width direction.

7. The current sensing system as claimed in claim 5, wherein: The first sensing point and the second sensing point are placed far away from the thickness centerline, and the distances of the two from the thickness centerline are approximately equal. The thickness centerline is set as the x-axis of the coordinate system, and the intersection of the thickness centerline and the width centerline is the coordinate zero point of the coordinate system.

8. The current sensing system as claimed in claim 5, wherein: The first sensing point and the second sensing point are placed along the thickness centerline, which is set as the x-axis of the coordinate system, and the intersection of the thickness centerline and the width centerline is the coordinate zero point of the coordinate system.

9. The current sensing system as described in claim 7 or 8, further comprising: A first small magnetic core, a second small magnetic core, a third small magnetic core, and a fourth small magnetic core are respectively located at each corner of the sensing plane, and the x-axis and z-axis form the sensing plane.

10. A current sensing system installed at an opening in a copper busbar, the opening being located in the middle of the copper busbar, the current sensing system comprising: At least one row of sensors, each row including at least two sensors distributed along the x-axis, the sensors measuring the magnetic field along the z-axis generated by the current flowing through the copper busbar; Operational amplifiers amplify the difference between the outputs of all sensors to generate an amplified signal; in The x-axis is the thickness centerline passing through the center of the copper busbar along the width direction, and the z-axis is the width centerline passing through the center of the copper busbar along the thickness direction.

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