Current detection device, battery management system, and electric device

Abstract

The embodiment of the present application provides a current detection device, a battery management system and a power utilization device, which can improve the precision of current detection. The current detection device comprises: a magnetic core configured to pass through a magnetic field generated by a detection current; a first coil; a second coil, the second coil and the first coil are both arranged on the magnetic core; an excitation circuit connected with the first coil and configured to provide an excitation signal to the first coil to drive the magnetic core to be magnetized alternately, and to induce the magnetic field generated by the detection current in the magnetic core through the first coil to generate an induced voltage signal on the first coil; a feedback circuit comprising an input end and an output end, the input end is connected with the excitation circuit, the output end is connected with the second coil, and the feedback circuit is configured to output a feedback current to the second coil based on the induced voltage signal, and to offset the magnetic field generated by the detection current through the feedback current to determine the current value of the detection current.

Description

Technical Field

[0001] This application relates to the field of current detection technology, and in particular to a current detection device, a battery management system, and an electrical device. Background Technology

[0002] Accurate current detection is one of the core issues in battery management. For example, inaccurate dark current detection during electric vehicle standby can lead to increased deviations in the battery's state of charge (SOC), thus affecting the assessment of the vehicle's range. Furthermore, inaccurate milliampere (mA) level trickle charging and discharging monitoring in energy storage systems can cause overcharging or over-discharging of the battery, thereby shortening its cycle life.

[0003] Therefore, improving the accuracy of current detection is an urgent problem to be solved. Utility Model Content

[0004] This application provides a current detection device, a battery management system, and an electrical device that can improve the accuracy of current detection.

[0005] In a first aspect, a current detection device is provided, comprising: a magnetic core configured to allow a magnetic field generated by a detection current to pass through; a first coil; a second coil, both the second coil and the first coil being wound on the magnetic core; an excitation circuit connected to the first coil, configured to provide an excitation signal to the first coil to drive the magnetic core to be alternately magnetized, and to sense the magnetic field generated by the detection current in the magnetic core through the first coil to generate an induced voltage signal on the first coil; and a feedback circuit including an input terminal and an output terminal, the input terminal being connected to the excitation circuit and the output terminal being connected to the second coil, configured to output a feedback current to the second coil based on the induced voltage signal, and to cancel the magnetic field generated by the detection current through the feedback current to determine the current value of the detection current.

[0006] In this embodiment, by setting a feedback circuit in the current detection device, i.e. introducing a closed-loop feedback compensation mechanism, the magnetic field generated by the feedback current actively cancels the bias magnetic field brought by the detection current. Compared with traditional current detection, this can significantly reduce detection error and thus improve the accuracy of current detection.

[0007] Furthermore, by setting up independent first and second coils connected to the excitation circuit and feedback circuit respectively, the decoupling and separation of AC excitation and DC feedback are achieved in the physical architecture. The first coil is used to process the AC waveform to extract the magnetic field deviation, while the second coil is used to input DC current to perform the magnetic field cancellation task. Both operate independently on the same magnetic core without interfering with each other. This structure effectively reduces noise interference caused by the coupling of AC and DC currents, and improves the overall device's anti-interference capability and operational stability.

[0008] In some possible implementations, the excitation circuit is configured to provide the excitation signal to the first coil to drive the magnetic core to be alternately magnetized in a non-saturated linear region.

[0009] By controlling the magnetization process within the non-saturated linear range, the first coil can be in a stable inductive state, resulting in a more stable response to changes in the excitation signal. This ensures that all acquired waveform data are valid and can be directly used in subsequent waveform calculations, reducing the interference of peak data in the invalid flip region on the algorithm and improving the reliability of the data processing logic and the accuracy of calculating minute currents.

[0010] In some possible implementations, the excitation circuit further includes a comparator circuit, the input of which is connected to the first coil, the comparator circuit being configured to acquire the induced voltage signal and detect the rate of change of the induced voltage signal; wherein the excitation circuit is configured to stop providing the current excitation signal to the first coil when the rate of change of the induced voltage signal is greater than or equal to a first rate of change threshold.

[0011] The above technical solution includes a comparison circuit connected to the first coil. This comparison circuit can detect the rate of change of the induced voltage signal. When the rate of change of the induced voltage signal is greater than a first rate of change threshold, the excitation circuit stops providing the current excitation signal to the first coil, so that the magnetic core can be alternately magnetized in the unsaturated linear range, thus protecting the linear characteristics of the signal acquisition range.

[0012] In some possible implementations, the excitation circuit further includes a drive control circuit and a commutation drive circuit. The input terminal of the drive control circuit is connected to the output terminal of the comparator circuit, the output terminal of the drive control circuit is connected to the input terminal of the commutation drive circuit, and the output terminal of the commutation drive circuit is connected to the first coil. The drive control circuit is configured to control the commutation drive circuit to switch the excitation signal when the rate of change of the induced voltage signal is greater than or equal to a first rate of change threshold, causing the magnetic core to perform a current storage process. During the current storage process, when the rate of change of the induced voltage signal decreases to a second rate of change threshold, the drive control circuit provides an excitation signal of opposite polarity to the first coil. The second rate of change threshold is less than the first rate of change threshold.

[0013] The above technical solution constructs a smooth transition cycle of "chopping cut-current storage buffer-reverse excitation". It uses the physical characteristics of inductor's natural current storage to smoothly introduce reverse excitation. This not only enables the magnetic core to avoid the ineffective saturation reversal region as much as possible, forming an extremely stable alternating magnetization cycle, but also provides highly symmetrical basic data support for the subsequent accurate extraction of the positive and negative period integration time of the waveform.

[0014] In some possible implementations, the feedback circuit further includes: a signal processing circuit, the input of which is connected to the output of the excitation circuit, configured to receive the induced voltage signal output by the excitation circuit and output a control voltage signal for canceling the magnetic field generated by the detection current in the magnetic core; and a conditioning circuit, the input of which is connected to the output of the signal processing circuit and the output of which is connected to the second coil, configured to convert the received control voltage signal into the feedback current and input the feedback current into the second coil.

[0015] This technical solution, by setting a signal processing circuit and a conditioning circuit in the feedback circuit, can not only effectively output a control voltage signal to cancel the magnetic field generated by the detection current in the magnetic core, but also solve the hardware limitation that the signal processing circuit cannot directly output current to drive the second coil by introducing a conditioning circuit. This makes the DC driving force that is finally fed back into the second coil for magnetic field cancellation stable, accurate and reliable.

[0016] In some possible implementations, the signal processing circuit is configured to calculate the integral of the induced voltage signal in both positive and negative periods, extract the integral difference, and output the control voltage signal based on the integral difference.

[0017] The above technical solution uses a signal processing circuit to extract the difference between the waveform's ampere-hour integrals, transforming the minute time distortion caused by magnetic field changes into a precisely quantifiable area difference. This not only makes full use of all the sampled data in the non-saturated linear range, but also provides a relatively accurate target for the subsequent dynamic approximation of the zero flux state of the system, namely, pursuing an integral difference of 0, thereby improving the calculation accuracy in the small current range.

[0018] In some possible implementations, the feedback circuit further includes: a sampling circuit connected to the excitation circuit and configured to acquire and output the induced voltage signal; an amplification circuit, the input of which is connected to the sampling circuit and configured to amplify the acquired induced voltage signal; and a signal conversion circuit, the input of which is connected to the output of the amplification circuit and configured to convert the amplified induced voltage signal into a digital signal; wherein the feedback circuit is configured to output a feedback current based on the digital signal.

[0019] The above technical solution, by setting up a sampling circuit, an amplification circuit, and a signal conversion circuit in the feedback circuit, improves the signal-to-noise ratio of weak electrical signals and the overall anti-interference capability of the system through a three-stage structure of "sampling-amplification-conversion". It also improves the quality and accuracy of the feedback current used to cancel the detection current, laying the foundation for high-precision measurement of current detection.

[0020] In some possible implementations, the current detection device further includes a storage circuit connected to the output of the feedback circuit for storing the current value of the received detected current. The above technical solution, by incorporating a storage circuit into the current detection device, endows the device with long-term local storage of high-precision current data and the ability to trace back historical states. By securely storing high-precision current values, it provides direct and reliable underlying data support for the BMS to perform accurate SOC estimation, SOH assessment, and extend battery cycle life, effectively preventing the risks of battery depletion, overcharging, or over-discharging caused by long-term unrecorded small current losses.

[0021] In some possible implementations, the magnetic core is made of a soft magnetic material with a permeability greater than a permeability threshold.

[0022] In this technical solution, the magnetic core is made of a soft magnetic material with high permeability. In this way, even if a very weak bias magnetic field is generated by a weak current in the outside, the magnetic core can sensitively sense the change in magnetic flux, which improves the sensitivity of the magnetic component to small magnetic fields, thereby further improving the overall detection accuracy of the current detection device.

[0023] In some possible implementations, the excitation circuit is configured to continuously sense the magnetic field that is not canceled by the detection current and generate a new induced voltage signal based on the uncancelled magnetic field until the feedback current output by the feedback circuit cancels out the magnetic field generated by the detection current, so that the current detection device is in a zero flux state.

[0024] The above technical solution achieves a dynamic approximation cyclic detection process by continuously sensing and detecting the magnetic field that has not been canceled by the current through the excitation circuit. This effectively reduces the residual error caused by incomplete compensation in a single operation and further improves the accuracy of current detection.

[0025] In some possible implementations, the feedback circuit is configured to: when the current detection device reaches a zero flux state, determine the sum of the cumulative output feedback currents as the total feedback current, and determine the current value of the detection current based on the total feedback current.

[0026] The above technical solution obtains the current value of the detection current by summing up multiple small compensation currents, thereby improving the accuracy of the detection current and realizing high-precision measurement within a small current range.

[0027] In a second aspect, a battery management system is provided, comprising: the current detection device described in the first aspect, configured to detect the current of a battery.

[0028] Thirdly, an electrical device is provided, comprising: a battery for storing or providing electrical energy; and a battery management system as described in the second aspect for managing the battery. Attached Figure Description

[0029] Figure 1 A schematic diagram of a current detection device according to an embodiment of this application is shown.

[0030] Figure 2 A schematic diagram of the magnetization characteristics of a magnetic core when the detection current is zero is shown.

[0031] Figure 3 It shows Figure 2 The corresponding core drive voltage sampling waveform when the detection current is zero.

[0032] Figure 4 A schematic diagram of the magnetization characteristics of a magnetic core when the detection current is not zero is shown.

[0033] Figure 5 It shows Figure 4 The corresponding core drive voltage sampling waveform when the detection current is not zero.

[0034] Figure 6A schematic diagram of another current detection device according to an embodiment of this application is shown.

[0035] Figure 7 A schematic diagram of the core drive voltage sampling waveform corresponding to a conventional scheme is shown.

[0036] Figure 8 A schematic diagram of another current detection device according to an embodiment of this application is shown.

[0037] Figure 9 A schematic diagram of another current detection device according to an embodiment of this application is shown.

[0038] Figure 10 A schematic diagram of another current detection device according to an embodiment of this application is shown.

[0039] Figure 11 A schematic diagram of another current detection device according to an embodiment of this application is shown.

[0040] Figure 12 A schematic diagram of another current detection device according to an embodiment of this application is shown.

[0041] Figure 13 A schematic diagram of another current detection device according to an embodiment of this application is shown.

[0042] Figure 14 A schematic diagram of an electrical device according to an embodiment of this application is shown.

[0043] Figure label: 100 - Current detection device; 110 - Excitation circuit; 112 - Comparison circuit; 113 - Drive control circuit; 114 - Commutation drive circuit; 120 - Feedback circuit; 122 - Signal processing circuit; 123 - Conditioning circuit; 124 - Sampling circuit; 125 - Amplification circuit; 126 - Signal conversion circuit; 130 - Magnetic core; 140 - Coil; 141 - First coil; 142 - Second coil; 150 - Storage circuit; 200 - Electrical device; 210 - Battery; 220 - Battery management system. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, rather than to describe a specific order or hierarchy.

[0046] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0047] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0048] In this application, "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0049] With the increasing energy shortage in modern society, electric vehicles, as a new energy vehicle, have received widespread attention since their introduction. Electric vehicles typically support Sentinel Mode, a function that allows them to monitor their surroundings while parked, identify potential threats (such as collisions or theft), and ensure vehicle safety by recording video, triggering alarms, or sending notifications.

[0050] Sentry mode typically relies on battery power. However, current detection in EVs using Sentry mode is often inaccurate. For example, non-contact electromagnetic sensors have an accuracy of approximately 100 mA when detecting small currents. For EVs with Sentry mode active for extended periods, this inaccuracy can lead to increased battery SOC deviation, resulting in battery depletion. This can affect the assessment of the EV's range and may even cause the EV to break down.

[0051] In addition, inaccurate milliampere-level trickle charge / discharge monitoring in energy storage systems may cause overcharging or over-discharging of the battery, thereby shortening the battery's cycle life.

[0052] Therefore, improving the accuracy of current detection is an urgent problem to be solved.

[0053] Therefore, this application provides a current detection device, which includes a magnetic core, a coil, an excitation circuit, and a feedback circuit. The magnetic core is configured to allow the magnetic field generated by the detection current to pass through it. The coil is wound around the magnetic core. The excitation circuit is connected to the coil and configured to sense the magnetic field generated by the detection current in the magnetic core through the coil, and output an induced voltage signal. The feedback circuit includes an input terminal and an output terminal. The input terminal is connected to the excitation circuit, and the output terminal is connected to the coil. It is configured to output a feedback current based on the induced voltage signal, and the feedback current cancels out the magnetic field generated by the detection current to determine the current value of the detection current. By setting a feedback circuit in the current detection device, i.e., introducing a closed-loop feedback compensation mechanism, the magnetic field generated by the feedback current actively cancels the bias magnetic field caused by the detection current. Compared with traditional current detection, this significantly reduces detection errors, thereby improving the accuracy of current detection.

[0054] The technical solutions described in the embodiments of this application are applicable to various battery-powered devices, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, electric cars, ships, and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0055] It should be understood that the technical solutions described in the embodiments of this application are not limited to the devices described above, but can also be applied to all devices that use batteries. However, for the sake of brevity, the following embodiments are all illustrated using electric vehicles as an example.

[0056] Regarding the type of battery, the battery in this application embodiment can be any type of battery, including but not limited to: lithium-ion batteries, lithium metal batteries, lithium-sulfur batteries, lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, lithium-air batteries, sodium batteries, etc. For example, a lithium-ion battery can be a ternary lithium battery, a lithium iron phosphate battery, etc. Regarding the size of the battery, the battery in this application embodiment can be a battery module or a battery pack, etc. In this application embodiment, the specific type and size of the battery are not specifically limited.

[0057] Figure 1An embodiment of this application illustrates a current detection device 100, which includes an excitation circuit 110, a feedback circuit 120, a magnetic core 130, and a coil 140. The magnetic core 130 is configured to allow a magnetic field generated by the detection current to pass through it. The coil 140 is wound around the magnetic core 130. The excitation circuit 110 is connected to the coil 140 and is configured to sense the magnetic field generated by the detection current in the magnetic core 130 through the coil 140, and output an induced voltage signal. The feedback circuit 120 includes an input terminal and an output terminal. The input terminal is connected to the excitation circuit 110, and the output terminal is connected to the coil 140. It is configured to output a feedback current based on the induced voltage signal, and the feedback current cancels out the magnetic field generated by the detection current to determine the current value of the detection current.

[0058] The current detection device 100 can be a current sensor, such as a fluxgate current sensor. During operation, an excitation signal is applied to the excitation coil of the fluxgate current sensor, causing the magnetic core to be alternately magnetized in both positive and negative directions. When there is no current in the conductor being measured, the magnetization of the magnetic core is symmetrical in both positive and negative half-cycles, resulting in a symmetrical voltage waveform induced by the coil and an average output of zero. When current is present in the conductor, this current generates an external magnetic field, superimposed on the magnetic core, causing the magnetization of the core to become asymmetrical in both directions. This leads to a distortion in the voltage waveform induced by the coil, generating even-order harmonic components proportional to the measured magnetic field. By processing these harmonic components, an electrical signal proportional to the magnitude of the measured current can be obtained, thereby achieving high-precision current detection. The fluxgate current sensor features high sensitivity, low temperature drift, and strong anti-interference capability.

[0059] like Figures 2-5 As shown, where, Figure 2 and Figure 4 In this context, H represents the magnetic field strength, generated by the detection current, and B is the magnetic flux density inside the magnetic core. B increases linearly with the increase of the external magnetic field generated by the detection current, eventually reaching saturation. In a fluxgate current sensor, when the direction of the bias magnetic field generated by the detection current is consistent with the positive excitation direction of the coil, the time for the core to reach saturation through positive magnetization is shortened, while the time for it to reach saturation through reverse magnetization is increased. Figure 3 It can be seen that the voltage waveform is symmetrical when the detected current is zero. Figure 5 It can be seen that the voltage waveform is asymmetrical when the detected current is not zero.

[0060] The detection current can be the external target current that the current detection device 100 needs to measure, such as the main circuit current of the battery in an electric vehicle. The detection current can also be referred to as the primary current.

[0061] In this embodiment, by setting a feedback circuit 120 in the current detection device 100, a closed-loop feedback compensation mechanism is introduced. The magnetic field generated by the feedback current actively cancels the bias magnetic field brought by the detection current. Compared with traditional current detection, the detection error can be greatly reduced, thereby improving the accuracy of current detection.

[0062] Optionally, the feedback circuit 120 may output a feedback current only once, and at the same time, the feedback current may only cancel the magnetic field generated by the detection current once.

[0063] Optionally, considering that the accuracy improvement of a single feedback compensation is usually limited, the embodiments of this application may perform multiple feedback compensations.

[0064] Specifically, the excitation circuit 110 can be configured to continuously sense the magnetic field that is not canceled by the detection current and generate a new induced voltage signal based on the uncancelled magnetic field until the feedback current output by the feedback circuit 120 cancels the magnetic field generated by the detection current, so that the current detection device 100 is in a zero flux state.

[0065] The phrase "until the feedback current output by the feedback circuit 120 cancels out the magnetic field generated by the detection current" can be understood as: the feedback current output by the feedback circuit 120 completely cancels out the magnetic field generated by the detection current, or, after the feedback current output by the feedback circuit 120 cancels out the magnetic field generated by the detection current, the remaining magnetic field is within a preset range.

[0066] The zero flux state can refer to a dynamic equilibrium state in which the positive bias magnetic field generated by the detection current and the reverse compensation magnetic field generated by the feedback current in the current detection device 100 are exactly equal in magnitude or within a preset range but opposite in direction.

[0067] For example, suppose the actual detected current is 10A. During the initial detection and feedback, the current detection device 100 may have errors. The feedback current calculated and output by the feedback circuit 120, after conversion, only cancels 9A of the magnetic field. At this time, the current detection device 100 is not in a zero-flux state, but still has 1A of uncancelled magnetic field. The excitation circuit 110 continues to sense the remaining 1A magnetic field and generates a new small deviation signal. After receiving the new signal, the feedback circuit 120 outputs a supplementary current to cancel the 0.9A magnetic field. At this time, 0.1A remains uncancelled. The current detection device 100 continues to cycle through this process, repeatedly and dynamically adjusting, until the uncancelled magnetic field is reduced to zero, so that the current detection device 100 reaches a dynamic zero-flux state.

[0068] The above technical solution, the excitation circuit 110 realizes a dynamic approximation cyclic detection process by continuously sensing and detecting the magnetic field that is not canceled by the current, which can effectively reduce the residual error caused by incomplete compensation in a single operation and further improve the accuracy of current detection.

[0069] In this case, the feedback circuit 120 can be configured to: when the current detection device 100 reaches a zero magnetic flux state, determine the sum of the cumulative output feedback currents as the total feedback current, and determine the current value of the detection current based on the total feedback current.

[0070] The sum of the cumulative output feedback currents can be the sum of the cumulative output feedback currents during each cycle, that is, the cumulative value of all the gradually approaching small compensation currents from the start of detection by the current detection device 100 to the point of reaching the dynamic zero magnetic flux state. For example, continuing the previous example, after the current detection device 100 reaches the zero magnetic flux state after multiple cycles, the feedback circuit 120 will accumulate the compensation currents given in each cycle, i.e., 9A + 0.9A + 0.1A = 10A.

[0071] After obtaining the total feedback current, the feedback circuit 120 can determine the current value of the detection current, i.e. the primary current, based on the total feedback current and the number of coil turns in the feedback circuit 120.

[0072] Alternatively, the feedback circuit 120 can determine the current value of the detected current according to the following formula: Ip=N Is Where Ip is the current value of the detected current, N is the number of coil turns in the feedback circuit 120, and Is is the total feedback current.

[0073] The above technical solution obtains the current value of the detection current by summing up multiple small compensation currents, thereby improving the accuracy of the detection current and realizing high-precision measurement within a small current range.

[0074] Optionally, the magnetic core 130 can be made of a soft magnetic material. The permeability of the soft magnetic material can be greater than a permeability threshold. A permeability greater than the permeability threshold can be understood as a high-permeability soft magnetic material. For example, the permeability threshold can be greater than or equal to 10,000, such as 15,000, 20,000, etc. The soft magnetic material can include, but is not limited to, iron-nickel alloys, amorphous alloys, nanocrystalline alloys, ferrites, iron-silicon alloys, iron-based nanocrystalline soft magnetic materials, etc.

[0075] The magnetic core 130 is made of a soft magnetic material with high permeability. In this way, even if a very weak bias magnetic field is generated by a weak current in the outside, the magnetic core 130 can sensitively sense the change in magnetic flux, which improves the sensitivity of the magnetic component to small magnetic fields, thereby further improving the overall detection accuracy of the current detection device 100.

[0076] In addition to soft magnetic materials, the magnetic core 130 can also be made of other materials.

[0077] It should be noted that different materials have different magnetic permeability, saturation magnetic induction intensity, and temperature characteristics. In this embodiment, a suitable magnetic core material can be selected according to the operating temperature range and accuracy requirements. It should also be noted that the current detection device 100 mentioned above being in a zero magnetic flux state actually means that the magnetic core 130 is in a dynamic zero magnetic flux state.

[0078] The magnetic core 130 can be a ring structure, and its geometric dimensions can be determined according to the magnitude of the detection current and the installation space. For example, the outer diameter of the magnetic core 130 can be 20 mm, the inner diameter can be 15 mm, and the height can be 10 mm.

[0079] In some embodiments, the excitation circuit 110 and the feedback circuit 120 may share a single coil.

[0080] In other embodiments, such as Figure 6 As shown, coil 140 may include a first coil 141 and a second coil 142. Both the first coil 141 and the second coil 142 are wound on the magnetic core 130. Excitation circuit 110 is connected to the first coil 141 and is configured to provide an excitation signal to the first coil 141 to drive the magnetic core 130 to be alternately magnetized and generate an induced voltage signal on the first coil 141. Feedback circuit 120 is connected to the second coil 142 and is configured to output a feedback current to the second coil 142.

[0081] The first coil 141 and the second coil 142 can be made of conductive materials, such as copper, copper alloy, aluminum, gold-plated copper, etc.

[0082] The first coil 141 and the second coil 142 can be two independent closed winding paths uniformly wound around the outside of the magnetic core 130, together forming a complete magnetic component. The first coil 141 carries a fixed, periodic excitation signal, i.e., an AC signal, which drives the magnetic core 130 to perform alternating magnetization, thereby generating regular waveform characteristics inside. The second coil 142 carries a DC signal output from the feedback circuit 120.

[0083] After receiving the DC feedback current, the second coil 142 generates a DC magnetic field with a fixed direction inside the magnetic core 130, which is then superimposed on and cancels out the bias magnetic field generated by the detection current. During this cancellation process, the first coil 141 continues to sense the remaining uncancelled magnetic field changes inside the magnetic core 130 through its internal excitation signal.

[0084] It should be noted that N mentioned above refers to the number of turns of the coil in the feedback circuit 120, which is actually the number of turns of the second coil 142.

[0085] Optionally, the excitation signal can be a sine wave, square wave, triangular wave, or other periodic waveform signal. Different waveform signals have different spectral characteristics, and the embodiments of this application can select the waveform signal according to the specific application scenario. The excitation signal in the embodiments of this application can also be called an alternating signal.

[0086] This technical solution achieves decoupling of AC excitation and DC feedback in its physical architecture by setting up independent first coil 141 and second coil 142 connected to the excitation circuit and feedback circuit respectively. The first coil 141 processes the AC waveform to extract magnetic field deviation, while the second coil 142 inputs DC current to perform magnetic field cancellation. Both operate independently on the same magnetic core 130 without interfering with each other. This structure effectively reduces noise interference caused by AC-DC coupling, improving the overall device's anti-interference capability and operational stability.

[0087] In some embodiments, the first coil 141 can be configured to drive the magnetic core 130 to periodically enter a deep saturation state in both positive and negative directions based on an excitation signal.

[0088] In other embodiments, the first coil 141 may be configured to drive the magnetic core 130 to be alternately magnetized in a non-saturated linear region based on an excitation signal.

[0089] Unsaturated linear intervals can be combined Figures 2-5 To understand this, as the applied magnetic field H increases, the magnetic flux density B inside the magnetic core 130 initially increases linearly. This stable upward trend is the unsaturated linear region (or plateau region). However, when the magnetic field continues to increase and reaches an inflection point, the magnetization capability of the magnetic core 130 reaches its upper limit, and the signal will surge and distort, entering the saturated flip region. The unsaturated linear region does not include the saturated flip region where the signal surges or distorts after reaching the inflection point.

[0090] In traditional methods, the magnetic core 130 typically needs to be fully saturated to detect the current. Figure 7As shown, this will inevitably generate spike signal data in the flip region. However, the data in the flip region usually does not have a good linear correspondence and cannot be effectively used in subsequent accurate calculations.

[0091] Therefore, in this embodiment, the first coil 141 is configured to immediately switch the power supply or chop the magnetic core 130 before it reaches the saturation inflection point and enters the flip region. In other words, this embodiment discards useless data in the flip region and only retains data from the plateau region (i.e., the non-saturated linear region) for acquisition and processing.

[0092] Alternating magnetization refers to the physical process in which, during operation, the excitation circuit of the current detection device supplies a periodic excitation signal to the first coil 141, driving the magnetic core 130 to be repeatedly magnetized in both positive and negative directions. During this process, the magnetic induction intensity inside the magnetic core 130 periodically increases and decreases with the external magnetic field generated by the first coil 141.

[0093] The above technical solution controls the magnetization process within the non-saturated linear range, enabling the first coil 141 to be in a stable inductive state and respond relatively stably to changes in the excitation signal. This ensures that the acquired waveform data are all valid data and can be directly used in subsequent waveform calculations, reducing the interference of peak data in the invalid flip region on the algorithm, and improving the reliability of the data processing logic and the calculation accuracy of minute currents.

[0094] As an example, the excitation can be stopped by calculating the time, thereby achieving the purpose of alternating magnetization of the core 130 in the unsaturated linear range.

[0095] As another example, such as Figure 8 As shown, the excitation circuit 110 may further include a comparator circuit 112, the input of which is connected to the first coil 141 and configured to acquire an induced voltage signal and detect the rate of change of the induced voltage signal. The excitation circuit 110 is configured to stop providing the current excitation signal to the first coil 141 when the rate of change of the induced voltage signal is greater than or equal to a first rate of change threshold.

[0096] The comparator circuit 112 can be a high-speed comparator capable of rapidly responding to and capturing transient changes in analog signals. Alternatively, the comparator circuit 112 can be analog detection hardware composed of a differentiating circuit and a threshold trigger circuit, or it can be a digital logic processing unit in a digital signal processor (DSP) or field-programmable gate array (FPGA) used to perform rate-of-change calculations. It should be understood that any circuit capable of monitoring the slope change of the induced voltage signal in real time can serve as the comparator circuit 112 in this embodiment.

[0097] The rate of change of the induced voltage signal can refer to the slope of the induced voltage signal as it changes over time. As the excitation signal drives the magnetization process, when the magnetic core 130 gradually approaches the inflection point of magnetization saturation, the winding inductance inside the first coil 141 gradually decreases, causing the first coil 141 to approach a conducting state, resulting in a sharp increase in current. At this time, the induced voltage waveform obtained from the sampling terminal will show a sharp upward "surge" trend, i.e., a steep increase in slope.

[0098] The first rate of change threshold can be greater than or equal to 50%, such as 55%, 60%, 65%, 70%, 75%, or 80%.

[0099] A rate of change of the induced voltage signal greater than or equal to the first rate of change threshold can be interpreted as: the rate of change of the induced voltage signal is relatively large, and the magnetic core 130 is about to enter the nonlinear saturation region. (Continue to refer to...) Figure 3 and Figure 5 When the magnetic core 130 is magnetized smoothly (i.e., in the plateau region), the waveform has only a small, stable slope. However, when it approaches saturation, the waveform suddenly rises like a spike. At this point, the rate of change of the induced voltage signal is greater than or equal to the first rate of change threshold.

[0100] The excitation circuit 110 stops providing the current excitation signal to the first coil 141, which means that the excitation circuit 110 stops the forward or reverse power excitation output. This is equivalent to performing a chopping action, that is, interrupting the channel for injecting active alternating energy into the first coil 141, thereby preventing the magnetic core 130 from being forcibly magnetized in the current direction, that is, preventing the magnetic core 130 from entering a fully saturated state.

[0101] The above technical solution includes a comparison circuit 112 connected to the first coil 141. The comparison circuit 112 can detect the rate of change of the induced voltage signal. When the rate of change of the induced voltage signal is greater than a first rate of change threshold, the excitation circuit 110 switches the excitation signal, so that the magnetic core 130 can be alternately magnetized in the non-saturated linear range, thus protecting the linear characteristics of the signal acquisition range.

[0102] In some embodiments, such as Figure 9 As shown, the excitation circuit 110 may further include a drive control circuit 113 and a commutation drive circuit 114. The input terminal of the drive control circuit 113 is connected to the output terminal of the comparator circuit 112, the output terminal of the drive control circuit 113 is connected to the input terminal of the commutation drive circuit 114, and the output terminal of the commutation drive circuit 114 is connected to the first coil 141.

[0103] Optionally, the drive control circuit 113 can be a logic judgment and control circuit, and the commutation drive circuit 114 can be, for example, an H-bridge drive circuit, a full-bridge drive circuit, a push-pull drive circuit, etc. When the drive circuit is an H-bridge drive circuit, it can optionally consist of four power switching transistors, which can be at least one of MOSFETs, IGBTs, or transistors. By controlling the periodic switching of the H-bridge drive circuit's switching state, the current direction in the first coil 141 changes alternately, driving the magnetic core 130 to be alternately magnetized within the non-saturated linear range.

[0104] Optionally, the drive control circuit 113 and the comparator circuit 112 can be integrated into the same chip, for example, in a microcontroller unit (MCU) or a DSP. Alternatively, the drive control circuit 113 and the comparator circuit 112 can be implemented separately.

[0105] As an example, the drive control circuit 113 can be configured to control the commutation drive circuit 114 to switch the excitation signal when the rate of change of the induced voltage signal is greater than or equal to a first rate of change threshold, so that the magnetic core 130 performs a current storage process, and during the current storage process, when the rate of change of the induced voltage signal drops to a second rate of change threshold, control the commutation drive circuit 114 to provide an excitation signal of opposite polarity to the first coil 141, wherein the second rate of change threshold is less than the first rate of change threshold.

[0106] The second rate of change threshold can be less than or equal to 10%, such as 0%, 2%, 5%, 7%, 8%, etc.

[0107] The current storage process can be understood as follows: after the commutation drive circuit 114 switches the alternating power supply, due to the physical characteristic of the inductance of the winding of the first coil 141, the current inside the first coil 141 cannot change abruptly, thus maintaining the original direction and continuing to discharge energy naturally.

[0108] Specifically, combined Figure 5Taking a complete alternating magnetization cycle as an example, when there is a positive excitation signal U+ inside the first coil 141, the magnetic core 130 is in the positive magnetization stage. Due to the presence of winding inductance, the current in the coil slowly increases. As the magnetization process proceeds, when the magnetic core 130 approaches saturation, the inductance gradually decreases, and the first coil 141 approaches conduction, causing the current to increase. The comparator circuit 112 detects the rate of change of the induced voltage signal. When the rate of change of the induced voltage signal is greater than or equal to the first rate of change threshold, the drive control circuit 113 regulates the commutation drive circuit 114 to cut off the excitation signal, that is, the positive excitation stops before the magnetic core 130 reaches magnetization saturation. At this time, since the current in the inductor coil cannot change abruptly, the positive current storage process will continue. When the rate of change of the induced voltage signal drops to the second rate of change threshold, the drive control circuit 113 regulates the commutation drive circuit 114 to provide a reverse excitation signal U-, that is, the magnetic core 130 begins reverse magnetization and stops excitation before reverse magnetization saturation, and continues the negative current storage process. Positive excitation magnetization, positive current storage, negative excitation magnetization, and negative current storage together form a complete and symmetrical alternating magnetization cycle.

[0109] The above technical solution constructs a smooth transition cycle of "chopping cut-current storage buffer-reverse excitation". It uses the physical characteristics of inductor natural current storage to smoothly introduce reverse excitation. This not only enables the magnetic core 130 to avoid the ineffective saturation reversal region as much as possible, forming an extremely stable alternating magnetization cycle, but also provides highly symmetrical basic data support for the subsequent accurate extraction of the positive and negative period integration time of the waveform.

[0110] In some embodiments, such as Figure 10 As shown, the feedback circuit 120 may further include a signal processing circuit 122 and a conditioning circuit 123. The input terminal of the signal processing circuit 122 is connected to the output terminal of the excitation circuit 110, and is configured to receive the induced voltage signal output by the excitation circuit 110, and output a control voltage signal to counteract the magnetic field generated by the detection current in the magnetic core 130. The input terminal of the conditioning circuit 123 is connected to the output terminal of the signal processing circuit 122, and the output terminal of the conditioning circuit 123 is connected to the second coil 142, and is configured to convert the received control voltage signal into a feedback current, and input the feedback current to the second coil 142.

[0111] Optionally, the signal processing circuit 122 can perform integration on the received induced voltage signal. Of course, besides integration, the signal processing circuit can also perform other operations, such as summation, which sums the accumulated feedback currents from each cycle to obtain the total feedback current. Another example is ampere-turn ratio conversion, which calculates the detected current value using the aforementioned ampere-turn ratio formula.

[0112] In the case where the excitation circuit 110 includes the drive control circuit 113 and the comparator circuit 112, the signal processing circuit 122 may optionally be integrated with the drive control circuit 113 and the comparator circuit 112 in the same chip, for example, in an MCU or a DSP.

[0113] Alternatively, the conditioning circuit may be a conversion circuit composed of devices such as operational amplifiers and power switching transistors.

[0114] In practical operation, after processing the induced voltage signal, the signal processing circuit 122 typically outputs a low-voltage logic signal. However, because the second coil 142 requires an actual physical current to generate a magnetic field, the control voltage signal output by the signal processing circuit 122 cannot be directly supplied to the second coil 142. Instead, the conditioning circuit 123 needs to convert the received control voltage signal into a feedback current capable of driving the coil.

[0115] For example, suppose the current detection device 100 detects a 1A uncompensated magnetic field deviation. After a series of calculations, the signal processing circuit 122 outputs a corresponding weak control voltage signal (e.g., a few volts) to the conditioning circuit 123. Upon receiving this control voltage signal, the conditioning circuit 123 converts it according to the set circuit conversion ratio and outputs a 1A feedback current. Finally, this 1A feedback current is input to the second coil 142, thereby generating a reverse magnetic field inside the magnetic core 130 to perform the cancellation action.

[0116] This technical solution, by setting a signal processing circuit 122 and a conditioning circuit 123 in the feedback circuit 120, can not only effectively output a control voltage signal to cancel the magnetic field generated by the detection current in the magnetic core 130, but also solve the hardware limitation that the signal processing circuit 122 cannot directly output current to drive the second coil 142 by introducing the conditioning circuit 123, so that the DC driving force that is finally fed back into the second coil 142 for magnetic field cancellation is stable, accurate and reliable.

[0117] In one implementation, the signal processing circuit 122 can be specifically configured to calculate the integral of the induced voltage signal in the positive and negative periods respectively, extract the integral difference, and output a control voltage signal based on the integral difference.

[0118] Calculating the integral over both positive and negative periods can refer to the signal processing circuit 122 performing ampere-hour integration on the acquired induced voltage signal. Specifically, the positive sampling period is denoted as... The corresponding induced voltage signal is The negative period time of sampling is denoted as . The corresponding induced voltage signal is The signal processing circuit 122 will calculate the integral of the positive period. Integral quantity with negative period .

[0119] Extracting the integral difference means comparing the calculated positive and negative period integral values ​​and taking the difference, the magnitude of which is proportional to the magnitude of the bias generated by the detection current.

[0120] When there is no detected current, the forward magnetization / current storage process of the magnetic core 130 is symmetrical with the reverse magnetization / current storage process. That is, the positive cycle time... and negative period time The signals are equal in magnitude, and the positive and negative periods are also the same (only their directions differ). At this point, they cancel each other out, and the calculated integral difference is 0.

[0121] When a detection current is present, it generates a bias magnetic field with a fixed direction within the magnetic core 130. Assuming the direction of this bias magnetic field is consistent with the positive excitation magnetization direction of the first coil 141, the magnetic core 130, during positive magnetization, effectively has a "lead time," thus shortening the time it takes to reach the first rate of change threshold. The size decreases. Conversely, when reverse magnetized, the core 130 not only undergoes the normal magnetization process but also needs to overcome and cancel out the positive bias magnetic field. Therefore, the time required to reach the first rate of change threshold during reverse magnetization increases, i.e. The time distortion causes the results of integrating the positive and negative periods to be unequal, resulting in a non-zero integral difference.

[0122] The control voltage signal used for cancellation based on the integral difference output means that there is a fixed proportional relationship between the integral difference and the magnitude of the detected current. Therefore, the signal processing circuit 122 will perform calibration based on this fixed ratio and calculate the required deviation correction value.

[0123] After completing the calibration described above, the signal processing circuit 122, since its pins can typically only process and output weak electrical signals and cannot directly supply physical current to the second coil 142, will convert the calculated correction value into a control voltage signal and output it to the conditioning circuit 123. Upon receiving this control voltage signal, the conditioning circuit 123 can convert it into a DC feedback current (e.g., a 1A current) to drive the second coil 142.

[0124] In the above technical solution, the signal processing circuit 122 extracts the difference in the waveform's ampere-hour integral, transforming the minute time distortion caused by the magnetic field change into an area difference that can be accurately quantified. This not only makes full use of all the sampled data in the non-saturated linear interval, but also provides a relatively accurate judgment target for the subsequent dynamic approximation of the zero magnetic flux state of the system, that is, pursuing an integral difference of 0, thereby improving the calculation accuracy in the small current range.

[0125] Of course, in addition to performing integration on the induced voltage signal, the signal processing circuit 122 can also be configured to process the induced voltage signal in other ways to extract a bias amount characterizing the magnitude of the detection current.

[0126] For example, the signal processing circuit 122 can be configured to determine the current value of the detected current by even-order harmonic extraction. Specifically, when there is current in the conductor being measured, the bias magnetic field generated by the detected current is superimposed on the magnetic core 130, causing an asymmetrical distortion of the voltage waveform induced by the first coil 141 and generating even-order harmonic components proportional to the measured bias magnetic field. The signal processing circuit 122 can be configured to extract and process the even-order harmonic components in the induced voltage signal using a filtering algorithm, thereby obtaining a difference signal proportional to the magnitude of the detected current.

[0127] For example, the signal processing circuit 122 can determine the current value of the detected current by measuring the time difference between forward and reverse directions. Specifically, when a bias magnetic field generated by the detected current exists, the time taken for the magnetic core 130 to reach the first rate of change threshold in the forward and reverse magnetization directions will be distorted by one being longer and the other shorter. The signal processing circuit 122 can be configured to measure the durations t1 and t2 of the induced voltage signal in the forward and reverse excitation directions, respectively, and calculate the deviation signal generated by the detected current based on the time difference between t1 and t2.

[0128] Furthermore, such as Figure 11 As shown, the feedback circuit 120 may further include a sampling circuit 124, an amplification circuit 125, and a signal conversion circuit 126. The sampling circuit 124 is connected to the excitation circuit 110 and is configured to acquire and output an induced voltage signal. The input terminal of the amplification circuit 125 is connected to the output terminal of the sampling circuit 124 and is configured to amplify the acquired induced voltage signal. The input terminal of the signal conversion circuit 126 is connected to the output terminal of the amplification circuit 125 and is configured to convert the amplified induced voltage into a digital signal. The feedback circuit 120 is configured to output a feedback current based on this digital signal.

[0129] The sampling circuit 124 may be, for example, a sampling resistor. When the excitation circuit 110 includes a commutation drive circuit 114, the sampling circuit 124 may be connected to the commutation drive circuit 114 to extract and convert the magnetization physical characteristics inside the first coil 141 into a continuous, periodic analog voltage signal. When the excitation circuit 110 includes a comparator circuit 112, the comparator circuit 112 is also connected to the sampling circuit 124 and configured to detect the rate of change of the induced voltage signal at the sampling circuit 124.

[0130] The amplifier circuit 125 can be, for example, an operational amplifier, and optionally, a programmable gain amplifier. Since the waveform distortion signal is extremely weak in scenarios involving minute currents (such as mA-level dark current), direct reading is easily affected by external noise. Therefore, amplifying the induced voltage signal using the amplifier circuit 125 can reduce the impact of external noise on current detection. Furthermore, the amplification of the induced voltage signal by the amplifier circuit 125 ensures that the amplitude of the amplified induced voltage signal matches the acquisition range of the signal conversion circuit 126.

[0131] Alternatively, the amplification factor of the amplifier circuit 125 can be the same regardless of the value of the induced voltage signal. For example, if the voltage value of the induced voltage signal is 1V, the amplifier circuit 125 can amplify it by 10 times; if the voltage value of the induced voltage signal is 5V, the amplifier circuit 125 will still amplify it by 10 times.

[0132] Optionally, the amplification factor of amplifier circuit 125 can be different for different induced voltage signals.

[0133] The signal conversion circuit 126 may be an analog-to-digital converter (ADC). For example, the signal conversion circuit 126 may be an ADC peripheral circuit directly integrated into the MCU, or it may be a separate high-precision ADC chip used to discretize continuous analog signals.

[0134] When the feedback circuit 120 includes the signal processing circuit 122, the output terminal of the signal conversion circuit 126 can be connected to the input terminal of the signal processing circuit 122.

[0135] The above technical solution, by setting up a sampling circuit 124, an amplification circuit 125, and a signal conversion circuit 126 in the feedback circuit 120, improves the signal-to-noise ratio of weak electrical signals and the overall anti-interference capability of the system through a three-stage structure of "sampling-amplification-conversion". This improves the quality and accuracy of the feedback current used to cancel the detection current, laying the foundation for high-precision measurement of current detection.

[0136] Furthermore, such as Figure 12As shown, the current detection device 100 may further include a storage circuit 150, which is connected to the output terminal of the feedback circuit 120 and is used to store the current value of the received detection current.

[0137] The storage circuit 150 can be random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), etc.

[0138] When the feedback circuit 120 includes the signal processing circuit 122, the input terminal of the storage circuit 150 is connected to the output terminal of the signal processing circuit 122.

[0139] In the case where the current detection device 100 includes a signal processing circuit 122, an amplifier circuit 125, a signal conversion circuit 126, a comparator circuit 112, and a drive control circuit 113, the storage circuit 150 can be integrated into the MCU or other controller along with these circuits. Alternatively, the storage circuit 150 can also be an independently configured external high-reliability storage chip.

[0140] The output of the storage circuit 150 can be connected to an external device of the current detection device 100 to output the stored current value of the detected current to the external device. Optionally, the storage circuit 150 can randomly output the stored current value of the detected current to the external device, or it can periodically output the current value of the detected current to the external device.

[0141] During continuous operation, the current detection device 100 continuously calculates relatively accurate current values, such as extremely small currents with an error of less than 5mA. This high-precision data is not only useful for instantaneous monitoring but also has long-term analytical value. Therefore, through the storage circuit 150, this historical current data with time attributes can be securely recorded locally. For example, when an electric vehicle is parked for an extended period and in "Sentry Mode," the vehicle primarily relies on a small, milliampere (mA) level dark current from the battery for power. The storage circuit 150 continuously accumulates and stores the high-precision dark current values ​​detected over this extended period. When the vehicle restarts or the external battery management system (BMS) needs to perform a charge / discharge calculation, it can directly read the complete historical current consumption log from the storage circuit 150, thus accurately deducting the accumulated charge / discharge from this period. Similarly, in energy storage system applications, long-term trickle-current data during charging and discharging can also be recorded.

[0142] The above technical solution, by incorporating a storage circuit 150 into the current detection device 100, endows the current detection device 100 with long-term local storage of high-precision current data and the ability to trace back historical states. By securely storing high-precision current values, it provides direct and reliable underlying data support for the BMS to perform accurate SOC estimation, state of health (SOH) assessment, and extend battery cycle life, effectively preventing the risks of battery depletion, overcharging, or over-discharging caused by long-term unrecorded small current losses.

[0143] Figure 13 A schematic diagram of a specific current detection device according to an embodiment of this application is shown. The current detection device is a fluxgate current sensor, which includes a magnetic core, a first coil, a second coil, a commutation drive circuit, a sampling resistor, an amplification circuit, a conditioning circuit, and an MCU. The MCU integrates a high-speed comparator, a drive control circuit, an ADC, an integration calibration circuit, and a storage circuit. The magnetic core is made of a soft magnetic material with high permeability. Two sets of coils (i.e., the first coil and the second coil) are uniformly wound around the outside of the magnetic core to form a complete magnetic component. The sampling resistor, high-speed comparator, ADC, and integration calibration circuit are respectively the sampling circuit 124, the comparison circuit 112, the signal conversion circuit 126, and the signal processing circuit 122 in the aforementioned embodiment. The first rate of change threshold is 50%, and the second rate of change threshold is 0%.

[0144] in, Figure 13 The corresponding core drive voltage sampling waveform diagram can be referenced. Figure 5 .

[0145] When a positive excitation signal U+ is applied to the first coil, the magnetic core is in the positive magnetization stage. Due to the inductance of the winding, the current in the first coil slowly increases. The high-speed comparator inside the MCU monitors the rate of change of the induced voltage signal across the sampling resistor in real time. When the magnetic core approaches saturation, the inductance gradually decreases, and the first coil approaches conduction, causing a surge in current. That is, when the high-speed comparator detects a signal change rate at the sampling resistor that is greater than or equal to 50%, the drive control circuit immediately regulates the commutation drive circuit to cut off the excitation signal, thus stopping the positive excitation before the magnetic core reaches magnetization saturation. At this time, since the current in the inductor coil cannot change abruptly, the magnetization process will continue into the positive current storage stage. When the current storage causes the signal change rate at the sampling resistor to drop to 0%, the drive control circuit again regulates the commutation drive circuit to provide a reverse excitation signal U- to the first coil. The magnetic core then begins reverse magnetization and stops excitation before reverse magnetization saturation, continuing the negative current storage process. Thus, positive excitation magnetization, positive current storage, negative excitation magnetization, and negative current storage together form a complete alternating magnetization cycle that is always in the non-saturated linear range.

[0146] After the sampling resistor extracts the periodic induced voltage signal, its weak amplitude is first amplified by the amplifier circuit, and then the ADC inside the MCU acquires and converts it into a digital signal, which is then input to the integration calibration circuit.

[0147] The integration calibration circuit combines the cut-off and flip-off cycles of the excitation signal to perform ampere-hour integration of the digital signal waveform within the positive and negative cycles. When the value of the detected current is not equal to 0, the bias magnetic field generated by the detected current in the magnetic core will cause a distortion in the forward and reverse magnetization times, with one being longer and the other shorter. At this time, the difference between the integrals of the positive and negative cycles is no longer zero, and this difference is proportional to the magnitude of the bias generated by the detected current.

[0148] The integral calibration circuit uses the aforementioned integral difference as the calibration basis, performs calibration according to a fixed ratio, and outputs a corresponding voltage signal to the conditioning circuit. The conditioning circuit converts this into a physical DC feedback current and injects it into the second coil. The reverse magnetic field generated by this feedback current in the second coil works together with the bias magnetic field generated by the detection current. The current detection device continuously cycles through the above "integration-comparison-output-compensation" steps, causing the magnetic core to continuously approach and eventually reach a dynamic zero flux state. At this time, the positive and negative periods of the sampling signal regain symmetry, and the integral difference is zero. At this point, the integral calibration circuit calculates the total feedback current accumulated when this state is reached, obtains a high-precision detection current according to the ampere-turns ratio formula, and stores it in the storage circuit.

[0149] This application also provides a battery management system, which includes a current detection device that can be configured to detect the current of the battery.

[0150] Optionally, the current detection device can be configured to detect the charging and discharging current of the battery main circuit, the milliampere-level trickle current of energy storage, or the dark current when the electrical device is parked for a long time.

[0151] Optionally, the current detection device may be the current detection device described in the foregoing embodiments.

[0152] like Figure 14 As shown in the figure, this application embodiment also provides an electrical device 200, which includes a battery 210 and a battery management system 220. The battery 210 is used to store or provide electrical energy, and the battery management system 220 is used to manage the battery 210.

[0153] Optionally, the battery management system 220 may be the battery management system described in the foregoing embodiments. The battery management system 220 manages the battery 210, and may perform at least one of the following functions: state monitoring, state analysis, charge / discharge control, safety protection, thermal management, high-voltage power distribution, and information management. In addition, the battery management system 220 may also implement the functions of the controller in the electrical device 200, such as implementing the functions of a vehicle control unit (VCU) or a motor control unit (MCU), etc., which is not limited in this application.

[0154] Alternatively, the electrical device 200 may be an electric vehicle, a ship, or a spacecraft, etc.

[0155] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A current detection device, characterized in that, include: The magnetic core is configured to allow the magnetic field generated by the detection current to pass through it; First coil; A second coil, both the second coil and the first coil are wound on the magnetic core; An excitation circuit, connected to the first coil, is configured to provide an excitation signal to the first coil to drive the magnetic core to be magnetized alternately, and to sense the magnetic field generated in the magnetic core by the detection current through the first coil to generate an induced voltage signal on the first coil. The feedback circuit includes an input terminal and an output terminal. The input terminal is connected to the excitation circuit, and the output terminal is connected to the second coil. It is configured to output a feedback current to the second coil based on the induced voltage signal, and to cancel the magnetic field generated by the detection current through the feedback current to determine the current value of the detection current.

2. The current detection device according to claim 1, characterized in that, The excitation circuit is configured to provide the excitation signal to the first coil to drive the magnetic core to be alternately magnetized in a non-saturated linear region.

3. The current detection device according to claim 2, characterized in that, The excitation circuit further includes: A comparator circuit, the input of which is connected to the first coil, is configured to acquire the induced voltage signal and detect the rate of change of the induced voltage signal; The excitation circuit is configured to stop providing the current excitation signal to the first coil when the rate of change of the induced voltage signal is greater than or equal to a first rate of change threshold.

4. The current detection device according to claim 3, characterized in that, The excitation circuit further includes a drive control circuit and a commutation drive circuit. The input terminal of the drive control circuit is connected to the output terminal of the comparator circuit, the output terminal of the drive control circuit is connected to the input terminal of the commutation drive circuit, and the output terminal of the commutation drive circuit is connected to the first coil. The drive control circuit is configured to control the commutation drive circuit to switch the excitation signal when the rate of change of the induced voltage signal is greater than or equal to the first rate of change threshold, so that the magnetic core can perform a current storage process. During the current storage process, when the rate of change of the induced voltage signal drops to the second rate of change threshold, the commutation drive circuit is configured to provide an excitation signal of opposite polarity to the first coil. The second rate of change threshold is less than the first rate of change threshold.

5. The current detection device according to any one of claims 1 to 4, characterized in that, The feedback circuit also includes: A signal processing circuit, wherein the input terminal of the signal processing circuit is connected to the output terminal of the excitation circuit, is configured to receive the induced voltage signal output by the excitation circuit, and output a control voltage signal for canceling the magnetic field generated by the detection current in the magnetic core; A conditioning circuit, the input of which is connected to the output of the signal processing circuit, and the output of which is connected to the second coil, is configured to convert the received control voltage signal into the feedback current and input the feedback current into the second coil.

6. The current detection device according to claim 5, characterized in that, The signal processing circuit is configured to calculate the integral of the induced voltage signal in the positive and negative periods respectively, extract the integral difference, and output the control voltage signal based on the integral difference.

7. The current detection device according to any one of claims 1 to 4, characterized in that, The feedback circuit also includes: A sampling circuit, connected to the excitation circuit, is configured to acquire and output the induced voltage signal; An amplifier circuit, the input of which is connected to the output of the sampling circuit, is configured to amplify the acquired induced voltage signal; A signal conversion circuit, wherein the input terminal of the signal conversion circuit is connected to the output terminal of the amplifier circuit, is configured to convert the amplified induced voltage signal into a digital signal; The feedback circuit is configured to output a feedback current based on the digital signal.

8. The current detection device according to any one of claims 1 to 4, characterized in that, The current detection device further includes: A storage circuit, connected to the output of the feedback circuit, is used to store the current value of the received detection current.

9. The current detection device according to any one of claims 1 to 4, characterized in that, The magnetic core is made of a soft magnetic material, the permeability of which is greater than a permeability threshold.

10. The current detection device according to any one of claims 1 to 4, characterized in that, The excitation circuit is configured to continuously sense the magnetic field that is not canceled by the detection current, and generate a new induced voltage signal based on the uncancelled magnetic field, until the feedback current output by the feedback circuit cancels out the magnetic field generated by the detection current, so that the current detection device is in a zero flux state.

11. The current detection device according to claim 10, characterized in that, The feedback circuit is configured to: when the current detection device reaches a zero magnetic flux state, determine the sum of the cumulative output feedback currents as the total feedback current, and determine the current value of the detection current based on the total feedback current.

12. A battery management system, characterized in that, include: The current detection device according to any one of claims 1 to 11 is configured to detect the current of a battery.

13. An electrical appliance, characterized in that, include: Batteries are used to store or provide electrical energy; The battery management system according to claim 12 is used to manage the battery.

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