Self-oscillation fluxgate current sensor circuit and working method

Abstract

The invention relates to a self-oscillation fluxgate current sensor circuit and a working method. Relates to the current sensor field. The circuit comprises a nonlinear magnetic core, an excitation winding, a comparator, a sampling resistor, a first resistor and a second resistor, the exciting winding is wound on the nonlinear magnetic core, one end is connected with the sampling resistor and the first input end of the comparator, and the other end is connected with the second resistor; the other end of the sampling resistor is grounded; one end of the first resistor is connected with the other end of the second resistor and the second input end of the comparator, and the other end is grounded; the current to be measured outputs excitation current to the nonlinear magnetic core; the excitation current generates a first voltage signal through the sampling resistor, the first resistor and the second resistor jointly generate a second voltage signal, the first voltage signal and the second voltage signal are input into the comparator, and under the condition that the voltage value of the obtained first voltage signal is larger than the voltage value of the second voltage signal, an output electric signal of the current to be measured is output. By adopting the circuit, the measurement precision of the fluxgate current sensor can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of current sensors, and in particular to a self-excited oscillation fluxgate current sensor circuit and a working method. Background Art

[0002] At present, accurate current measurement mainly converts the magnetic field changes generated by the current to be measured into electrical signals through the fluxgate effect. The magnetic field conversion process is inseparable from the current sensor, so improving the accuracy of the fluxgate current sensor is crucial.

[0003] In the related art, the fluxgate current sensor requires an independent excitation source to generate a magnetic field. Its working principle relies on the excitation current and the measured current acting on the sensor probe to make the annular core alternately in positive and negative saturation states, and then calculate the measured current by the difference between the coercive magnetic field and the measured magnetic field. However, changes in the characteristics of the annular core will lead to large measurement errors. Therefore, there is still a problem of low measurement accuracy of the fluxgate current sensor. Summary of the invention

[0004] Based on this, it is necessary to provide a self-excited oscillation fluxgate current sensor circuit and control method to address the technical problem of low measurement accuracy of the above-mentioned fluxgate current sensor.

[0005] In a first aspect, the present application provides a self-excited oscillation fluxgate current sensor circuit, the circuit comprising a nonlinear magnetic core, an excitation winding, a comparator, a sampling resistor, a first resistor, and a second resistor;

[0006] The excitation winding is wound on the nonlinear magnetic core, one end of the excitation winding is connected to the sampling resistor and the first input end of the comparator, and the other end is connected to the second resistor; the other end of the sampling resistor is grounded; one end of the first resistor is connected to the other end of the second resistor and the second input end of the comparator, and the other end of the first resistor is grounded;

[0007] The current to be measured outputs an excitation current to the nonlinear magnetic core through the excitation winding; the excitation current generates a first voltage signal through the sampling resistor, and the first voltage signal is input into the comparator; the first resistor and the second resistor jointly generate a second voltage signal, and the second voltage signal is input into the comparator; the comparator is used to output an output electrical signal for cutting off or adjusting the current to be measured in the excitation winding through a signal output terminal when the voltage value of the first voltage signal obtained is greater than the voltage value of the second voltage signal.

[0008] In one embodiment, the circuit further includes a winding resistor; one end of the winding resistor is connected to the excitation winding, and the other end of the winding resistor is connected to the first input end of the comparator; and is used to limit the current in the circuit.

[0009] In one of the embodiments, the circuit further comprises a primary winding; the primary winding is wound on the nonlinear magnetic core and is used to generate a magnetic field through the current to be measured; wherein the magnetic field affects the saturation time value of the excitation winding.

[0010] In one of the embodiments, the signal output terminal of the comparator is used to output a square wave signal.

[0011] In one embodiment, the square wave signal is used to excite the nonlinear magnetic core.

[0012] In a second aspect, the present application further provides a self-excited oscillation fluxgate current sensor working method, which is applied to the self-excited oscillation fluxgate current sensor circuit described in any of the above embodiments, wherein the circuit includes a nonlinear magnetic core, an excitation winding, a comparator, a sampling resistor, a first resistor, and a second resistor;

[0013] The excitation winding is wound on the nonlinear magnetic core, one end of the excitation winding is connected to the sampling resistor and the first input end of the comparator, and the other end is connected to the second resistor; the other end of the sampling resistor is grounded; one end of the first resistor is connected to the other end of the second resistor and the second input end of the comparator, and the other end of the first resistor is grounded;

[0014] The method comprises:

[0015] The current to be measured outputs an excitation current to the nonlinear magnetic core through the excitation winding; the excitation current generates a first voltage signal through the sampling resistor, and the first voltage signal is input into the comparator; the first resistor and the second resistor jointly generate a second voltage signal, and the second voltage signal is input into the comparator; the comparator is used to output an output electrical signal for cutting off or adjusting the current to be measured in the excitation winding through a signal output terminal when the voltage value of the first voltage signal obtained is greater than the voltage value of the second voltage signal.

[0016] In one embodiment, the circuit further includes a winding resistor; one end of the winding resistor is connected to the excitation winding, and the other end of the winding resistor is connected to the first input end of the comparator; and is used to limit the current in the circuit.

[0017] In one embodiment, the circuit further comprises a primary winding; the primary winding is wound on a nonlinear magnetic core, and is used for converting electrical energy into electromagnetic energy and transferring electrical energy to the secondary winding.

[0018] In one embodiment, the signal output terminal of the comparator is used to output a square wave signal.

[0019] In one embodiment, a square wave signal is used to excite the nonlinear magnetic core.

[0020] The self-excited oscillation fluxgate current sensor circuit comprises a nonlinear magnetic core, an excitation winding, a comparator, a sampling resistor, a first resistor and a second resistor; wherein the excitation winding is wound on the nonlinear magnetic core, one end of the excitation winding is connected to the sampling resistor and the first input end of the comparator, and the other end is connected to the second resistor; the other end of the sampling resistor is grounded; one end of the first resistor is connected to the other end of the second resistor and the second input end of the comparator, and the other end of the first resistor is grounded; the current to be measured outputs an excitation current to the nonlinear magnetic core through the excitation winding; the excitation current generates a first voltage signal through the sampling resistor, and the first voltage signal is input to the comparator; the first resistor and the second input end are connected to the sampling resistor and the second input end of ... of the comparator are connected to the sampling resistor and the second input end of the comparator; the first resistor and the second input end of the comparator are connected to the sampling resistor and the second input end of the comparator; the first resistor and the second input end of the comparator are connected to the sampling resistor and the second input end of the comparator; the first resistor and the second input end of the comparator are connected to the sampling resistor and the first input end of the compar The two resistors jointly generate a second voltage signal, and input the second voltage signal into a comparator; the comparator is used to output an output electrical signal for cutting off or adjusting the current to be measured in the excitation winding through a signal output terminal when the voltage value of the acquired first voltage signal is greater than the voltage value of the second voltage signal; in the above circuit, the excitation winding, the comparator, the sampling resistor, the first resistor and the second resistor form a circuit through a specific connection method, and the nonlinear magnetic core forms an oscillator through the circuit where the excitation winding is located, so that the output electrical signal of the current to be measured can be output without an external excitation source, thereby improving the measurement accuracy of the fluxgate current sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 is a schematic diagram of a self-oscillating fluxgate current sensor circuit in one embodiment;

[0023] Figure 2 is a schematic diagram of a self-oscillating fluxgate current sensor circuit including a wirewound resistor in one embodiment;

[0024] Figure 3 is a schematic diagram of a self-oscillating fluxgate current sensor circuit including a primary winding in one embodiment;

[0025] Figure 4It is a flowchart of a working method of a self-excited oscillation fluxgate current sensor in one embodiment;

[0026] Figure 5 Detailed step diagram of a working method of a self-excited oscillation fluxgate current sensor in one embodiment. DETAILED DESCRIPTION

[0027] The traditional oscillating fluxgate current sensor is based on the Faraday electromagnetic induction principle and uses a magnetic modulator and feedback control circuit to achieve accurate current measurement. Its core part consists of a high-permeability toroidal core, a measured winding and an excitation winding. The excitation winding receives an excitation signal from an external power supply, which is usually a sinusoidal waveform. The above sinusoidal waveform generates an alternating magnetic field in the core, causing the core to alternately saturate in the positive and negative directions. When the measured current passes through the measured winding, according to Ampere's law, a magnetic field proportional to the measured current will be generated around the core. This magnetic field will be superimposed with the magnetic field generated by the excitation winding and act on the core together. The detection coil senses the change in magnetic flux in the core and converts it into an electrical signal. After amplification, filtering and other processing, the electrical signal is input into the excitation winding as a feedback signal to form a closed-loop control system. Under the combined action of the excitation signal and the measured current, the magnetic permeability of the core will change over time, resulting in a magnetic modulation effect. This effect causes the voltage signal in the detection coil to contain high-frequency and low-frequency components. The low-frequency component is proportional to the magnitude of the measured current. By measuring the amplitude or phase of the low-frequency component, the value of the measured current can be accurately calculated.

[0028] Traditional oscillating fluxgate current sensors require an independent excitation source to generate a magnetic field. Their working principle relies on the excitation current and the measured current acting on the sensor probe to make the annular magnetic core alternately in positive and negative saturation states, and the measured current is calculated by the difference between the coercive force magnetic field and the measured magnetic field. Therefore, the traditional oscillating fluxgate current sensor can reduce the error by selecting a core material whose coercive force changes less with temperature, but in the case of large temperature changes, changes in other characteristics of the core will still lead to large measurement errors, and the stability is poor in high temperature environments; because the structure of the traditional oscillating fluxgate current sensor is relatively complex and is greatly affected by temperature, the application range is relatively limited; in order to ensure accuracy, frequent calibration is required, which increases maintenance costs and complexity, and the complex structure and multi-component design increase the difficulty and cost of maintenance; some fluxgate sensors may require higher energy input during self-excited oscillation, which will lead to overall low energy efficiency. If the signal generated by the sensor requires a complex post-processing circuit to extract effective information, the processing efficiency may be low.

[0029] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0031] It can be understood that the terms "first", "second", etc. used in the present application can be used in this article to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element.

[0032] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intermediate element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is transmission of electrical signals or data between the connected objects.

[0033] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0034] like Figure 1 As shown, a self-excited oscillation fluxgate current sensor circuit is provided, including a nonlinear magnetic core C1, an exciting winding W1, a comparator A1, a sampling resistor Rs, a first resistor R1 and a second resistor R2;

[0035] The excitation winding W1 is wound on the nonlinear magnetic core C1, one end of the excitation winding W1 is connected to the sampling resistor Rs and the first input end of the comparator A1, and the other end is connected to the second resistor R2; the other end of the sampling resistor Rs is grounded; one end of the first resistor R1 is connected to the other end of the second resistor R2 and the second input end of the comparator A1, and the other end of the first resistor R1 is grounded;

[0036] The measured current Ip outputs the excitation current to the nonlinear magnetic core C1 through the excitation winding W1; the excitation current generates a first voltage signal through the sampling resistor Rs, and the first voltage signal is input into the comparator A1; the first resistor R1 and the second resistor R2 jointly generate a second voltage signal, and the second voltage signal is input into the comparator A1; the comparator A1 is used to output an output electrical signal for cutting off or adjusting the measured current Ip in the excitation winding W1 through the signal output terminal when the voltage value of the acquired first voltage signal is greater than the voltage value of the second voltage signal.

[0037] Among them, self-excited oscillation refers to the situation where there is continuous oscillation due to an internal feedback mechanism without external driving; the magnetic permeability of the nonlinear magnetic core C1 changes with the change of magnetic field strength; and the comparator A1 is used to compare the sizes of two voltage signals.

[0038] As an example, by winding the excitation winding W1 on the nonlinear core C1, a closed magnetic flux path can be formed. When the current to be measured passes through the excitation winding W1, a strong magnetic field will be generated in the nonlinear core C1. The material properties of the nonlinear core C1 can enhance this magnetic field; and the excitation winding W1 wound on the nonlinear core C1 can increase the inductive inductance value. The increase in inductance can more effectively store and release energy, thereby improving the performance of the sensor; it can also reduce the occurrence of leakage flux; the high magnetic permeability characteristics of the nonlinear core C1 can make it possible to pass a small amount of current through the excitation winding W1. The current can generate a large magnetic flux in the nonlinear magnetic core C1, and can also work stably under different current and temperature conditions; when the measured current Ip passes through the excitation winding W1, a corresponding excitation current will be generated in the magnetic core, thereby causing a change in the magnetic flux; the first voltage signal is a voltage signal proportional to the excitation current generated by the excitation current passing through the sampling resistor Rs; the second voltage signal is a voltage signal of a threshold voltage provided by a voltage divider network composed of the first resistor R1 and the second resistor R2 for the input end of the comparator A1, wherein the threshold voltage is used to set the upper limit or lower limit of the excitation current.

[0039] The self-excited oscillation fluxgate current sensor circuit comprises a nonlinear magnetic core C1, an excitation winding W1, a comparator A1, a sampling resistor Rs, a first resistor R1 and a second resistor R2; wherein the excitation winding W1 is wound on the nonlinear magnetic core C1, one end of the excitation winding W1 is connected to the sampling resistor Rs and the first input end of the comparator A1, and the other end is connected to the second resistor R2; the other end of the sampling resistor Rs is grounded; one end of the first resistor R1 is connected to the other end of the second resistor R2 and the second input end of the comparator A1, and the other end of the first resistor R1 is grounded; the measured current Ip outputs an excitation current to the nonlinear magnetic core C1 through the excitation winding W1; the excitation current generates a first voltage signal through the sampling resistor Rs, and the first voltage signal is input to the comparator A1. 1; the first resistor R1 and the second resistor R2 jointly generate a second voltage signal, and input the second voltage signal into the comparator A1; the comparator A1 is used to output an output electrical signal for cutting off or adjusting the measured current Ip in the excitation winding W1 through the signal output terminal when the voltage value of the acquired first voltage signal is greater than the voltage value of the second voltage signal; in the above circuit, the excitation winding W1, the comparator A1, the sampling resistor Rs, the first resistor R1 and the second resistor R2 form a circuit through a specific connection method, and the nonlinear magnetic core C1 forms an oscillator through the circuit where the excitation winding W1 is located, so that the output electrical signal of the measured current Ip can be output without an external excitation source, thereby improving the measurement accuracy of the fluxgate current sensor.

[0040] In an exemplary embodiment, Figure 2 As shown, the circuit also includes a winding resistor Rc; one end of the winding resistor Rc is connected to the excitation winding W1, and the other end is connected to the first input end of the comparator A1; it is used to limit the current in the circuit.

[0041] The winding resistor Rc is the internal resistance of the excitation winding W1 or an additional resistor, which is usually manufactured by winding and has good thermal stability and high power carrying capacity. The winding resistor Rc will affect the working state of the circuit, for example, by limiting the current to prevent the excitation winding W1 from overheating.

[0042] As an example, the winding resistor Rc can prevent excessive current from flowing through the excitation winding W1. The main process is that when voltage is input to the excitation winding W1, Rc can provide a barrier so that the current is not too large, thereby protecting the entire circuit from overload damage.

[0043] In this embodiment, the wire-wound resistor Rc limits the current in the circuit, protects other circuit components from damage due to excessive current, and maintains the safety and stability of the circuit.

[0044] In one embodiment, Figure 3As shown, the circuit further includes a primary winding Wp; the primary winding Wp is wound on the nonlinear magnetic core C1 and is used to generate a magnetic field through the current to be measured Ip; wherein the magnetic field affects the saturation time value of the excitation winding W1.

[0045] Among them, the primary winding Wp has the function of converting the input electrical energy into electromagnetic energy, and generates a changing magnetic flux through the interaction between the current and the magnetic field; the saturation time value refers to the time required for the nonlinear magnetic core C1 to reach the saturation state after being affected by the magnetic field. The saturation state means that the magnetic flux density of the nonlinear magnetic core C1 reaches the maximum value, and further increase in current will not significantly increase the magnetic flux. The primary winding Wp transfers electrical energy to the secondary winding. According to the change in current, the secondary winding induces a voltage, which can be provided to the load or other circuit elements to achieve effective energy transfer.

[0046] In this embodiment, the primary winding Wp is responsible for converting electrical energy into electromagnetic energy and transmitting it to the secondary winding. By combining with the nonlinear magnetic core C1, the power conversion efficiency can be effectively improved to ensure the stable and reliable performance of the sensor.

[0047] In one embodiment, the signal output terminal of the comparator A1 is used to output a square wave signal.

[0048] Among them, the square wave signal is a periodic waveform, and its voltage quickly switches between two stable states within a certain period, namely a high level state and a low level state. It has clear rising and falling edges and can produce effective switching actions.

[0049] As an example, the comparator A1 generates a square wave signal with fixed amplitude and frequency. The square wave signal is used to excite the nonlinear magnetic core C1 until it is saturated. When the measured current passes through the primary winding Wp, it generates a bias magnetic field in the nonlinear magnetic core C1. The bias magnetic field destroys the symmetry of the excitation current and the excitation magnetic flux, thereby inducing a fluxgate effect.

[0050] In this embodiment, the signal output end of the comparator A1 can realize signal control and regulation in the current sensor by generating a square wave signal. The above square wave signal provides a high-frequency and stable control method through rapid level changes. Through reasonable design, the comparator A1 can effectively reduce the impact of noise and ensure the efficient operation of the circuit.

[0051] Further, in one embodiment, a square wave signal is used to excite the nonlinear magnetic core C1.

[0052] Here, excitation refers to applying an action on the nonlinear magnetic core C1 through an electrical signal to generate a change in the magnetic field. Correspondingly, it means that the above-mentioned square wave signal applies periodic energy input to the magnetic core through repeated level switching.

[0053] In this embodiment, the square wave signal is used to make the current in the primary winding Wp rise and fall rapidly, driving the magnetic flux in the magnetic core to change between extreme values. Therefore, the alternating magnetic field generated based on Faraday's law of electromagnetic induction can efficiently induce voltage in the secondary winding; and the periodic characteristics of the square wave signal can effectively promote the change of magnetic flux in the magnetic core, thereby improving the power conversion efficiency of the entire circuit.

[0054] Furthermore, the present application provides a self-excited oscillation fluxgate current sensor working method, which is applied to the self-excited oscillation fluxgate current sensor circuit mentioned in any of the above embodiments, the circuit includes a nonlinear magnetic core, an excitation winding, a comparator, a sampling resistor, a first resistor and a second resistor; the excitation winding is wound on the nonlinear magnetic core, one end of the excitation winding is connected to the sampling resistor and the first input end of the comparator, and the other end is connected to the second resistor; the other end of the sampling resistor is grounded; one end of the first resistor is connected to the other end of the second resistor and the second input end of the comparator, and the other end of the first resistor is grounded; the method includes:

[0055] Step S402: the current to be measured outputs an exciting current to the nonlinear magnetic core through the exciting winding.

[0056] Among them, self-excited oscillation refers to the situation where there is continuous oscillation due to the internal feedback mechanism without external driving; the magnetic permeability of the nonlinear magnetic core changes with the change of magnetic field strength.

[0057] Step S404 , the excitation current generates a first voltage signal through the sampling resistor, and the first voltage signal is input into the comparator; the first resistor and the second resistor jointly generate a second voltage signal, and the second voltage signal is input into the comparator.

[0058] Among them, the first voltage signal is a voltage signal proportional to the excitation current generated by the excitation current passing through the sampling resistor; the second voltage signal is a voltage signal of a threshold voltage provided as a reference to the input end of the comparator by a voltage divider network composed of the first resistor and the second resistor, wherein the threshold voltage is used to set the upper or lower limit of the excitation current.

[0059] Step S406: When the voltage value of the acquired first voltage signal is greater than the voltage value of the second voltage signal, the comparator outputs an output electrical signal for cutting off or adjusting the current to be measured in the excitation winding through the signal output terminal.

[0060] Among them, the comparator is used to compare the sizes of two voltage signals; the high magnetic permeability characteristics of the nonlinear magnetic core can generate a larger magnetic flux in the nonlinear magnetic core as long as a smaller current is passed through the excitation winding; when the current to be measured passes through the excitation winding, a corresponding excitation current will be generated in the magnetic core, thereby causing a change in the magnetic flux.

[0061] In one embodiment, the circuit further includes a winding resistor; one end of the winding resistor is connected to the excitation winding, and the other end is connected to the first input end of the comparator; and is used to limit the current in the circuit.

[0062] Furthermore, in one embodiment, the circuit further comprises a primary winding; the primary winding is wound on a nonlinear magnetic core and is used to generate a magnetic field through the current to be measured Ip; wherein the magnetic field affects the saturation time value of the excitation winding W1.

[0063] In one embodiment, the signal output terminal of the comparator is used to output a square wave signal.

[0064] In one exemplary embodiment, a square wave signal is used to excite the nonlinear magnetic core.

[0065] In the above embodiment, first, the current to be measured outputs the excitation current to the nonlinear magnetic core through the excitation winding; then the excitation current generates a first voltage signal through the sampling resistor, and the first voltage signal is input into the comparator; the first resistor and the second resistor jointly generate a second voltage signal, and the second voltage signal is input into the comparator; the comparator is used to output an output electrical signal for cutting off or adjusting the current to be measured in the excitation winding through the signal output terminal when the voltage value of the first voltage signal obtained is greater than the voltage value of the second voltage signal. Therefore, the nonlinear magnetic core forms an oscillator through the circuit where the excitation winding is located, and the output electrical signal of the current to be measured can be output without an external excitation source, thereby improving the measurement accuracy of the fluxgate current sensor.

[0066] Furthermore, in one embodiment, Figure 5 As shown, a specific construction and application steps of a self-excited oscillation fluxgate current sensor circuit are provided, including:

[0067] Step S502, obtaining components constituting the self-oscillation fluxgate current sensor circuit.

[0068] The components may include a nonlinear magnetic core made of a high magnetic permeability material, an excitation winding, a comparator, an excitation current sampling resistor, a threshold voltage setting resistor, a threshold voltage setting resistor, a winding resistor and a primary winding.

[0069] Step S504: the power supply excites the nonlinear magnetic core through the excitation winding.

[0070] The high magnetic permeability of the magnetic core allows a smaller current to be passed through the excitation winding to generate a larger magnetic flux in the magnetic core.

[0071] Step S506 : the excitation current passes through the sampling resistor to generate a voltage signal proportional to the excitation current.

[0072] The voltage signal proportional to the exciting current needs to be input to an input terminal of the comparator.

[0073] Step S508: The first threshold voltage setting resistor and the second threshold voltage setting resistor form a voltage dividing network.

[0074] After the voltage divider network is formed, a reference threshold voltage can be provided for another input terminal of the comparator, and the reference threshold voltage is used to set the upper limit or lower limit of the excitation current.

[0075] In step S510 , the comparator compares the sampled voltage signal with the threshold voltage.

[0076] If the sampled voltage exceeds the threshold voltage, it means that the excitation current exceeds the preset value, and the output of the comparator will change state.

[0077] Step S512, controlling the current in the excitation winding according to the output of the comparator.

[0078] The output of the comparator can be used to control the cutting off or adjusting the current in the exciting winding, so as to avoid core saturation or over-excitation.

[0079] More often, the winding resistance can represent the internal resistance of the excitation winding or an additional resistance that affects the working state of the circuit, for example, by limiting the current to prevent the winding from overheating; the primary winding can be part of the transformer, used to transfer energy to other windings, such as the secondary winding, under the control of the excitation current.

[0080] In the above embodiment, an oscillator is formed by the circuit where the nonlinear magnetic core and the excitation winding are located, and there is no need to connect an external excitation source. Therefore, the sensor works in a self-excited oscillation mode and does not require an external excitation signal. The self-excited oscillation fluxgate current sensor does not require an independent excitation source, thereby reducing the coercive force offset error caused by temperature changes. By establishing a relationship between the time difference between the front and rear half cycles of the excitation current and the measured current, the drive delay and power amplifier drift error are effectively offset, thereby improving the temperature stability of the sensor. The accuracy, response speed and anti-interference ability are also improved, thereby enabling the self-excited oscillation fluxgate current sensor to accurately monitor and control the current in the energy conversion process.

[0081] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0082] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A self-oscillating fluxgate current sensor circuit, characterized in that: The circuit includes a nonlinear magnetic core, an excitation winding, a comparator, a sampling resistor, a first resistor and a second resistor; The excitation winding is wound on the nonlinear magnetic core, one end of the excitation winding is connected to the sampling resistor and the first input end of the comparator, and the other end is connected to the second resistor; the other end of the sampling resistor is grounded; one end of the first resistor is connected to the other end of the second resistor and the second input end of the comparator, and the other end of the first resistor is grounded; The current to be measured outputs an excitation current to the nonlinear magnetic core through the excitation winding; The excitation current generates a first voltage signal through the sampling resistor, and the first voltage signal is input into the comparator; the first resistor and the second resistor jointly generate a second voltage signal, and the second voltage signal is input into the comparator; the comparator is used to output an output electrical signal for cutting off or adjusting the current to be measured in the excitation winding through a signal output terminal when the voltage value of the first voltage signal obtained is greater than the voltage value of the second voltage signal.

2. The circuit according to claim 1, characterized in that The circuit also includes a wirewound resistor; One end of the winding resistor is connected to the excitation winding, and the other end is connected to the first input end of the comparator; and it is used to limit the current in the circuit.

3. The circuit according to claim 1, characterized in that The circuit also includes a primary winding; The primary winding is wound on the nonlinear magnetic core and is used to generate a magnetic field through the current to be measured; wherein the magnetic field affects the saturation time value of the excitation winding.

4. The circuit according to claim 1, characterized in that The signal output terminal of the comparator is used to output a square wave signal.

5. The circuit according to claim 4, characterized in that The square wave signal is used to excite the nonlinear magnetic core.

6. A method for operating a self-oscillating fluxgate current sensor circuit, characterized in that: The self-excited oscillation fluxgate current sensor circuit applied to any one of claims 1 to 5, the circuit comprising a nonlinear magnetic core, an excitation winding, a comparator, a sampling resistor, a first resistor and a second resistor; The excitation winding is wound on the nonlinear magnetic core, one end of the excitation winding is connected to the sampling resistor and the first input end of the comparator, and the other end is connected to the second resistor; the other end of the sampling resistor is grounded; One end of the first resistor is connected to the other end of the second resistor and the second input end of the comparator, and the other end of the first resistor is grounded; The method comprises: The current to be measured outputs an excitation current to the nonlinear magnetic core through the excitation winding; The excitation current generates a first voltage signal through the sampling resistor, and the first voltage signal is input into the comparator; the first resistor and the second resistor jointly generate a second voltage signal, and the second voltage signal is input into the comparator; the comparator is used to output an output electrical signal for cutting off or adjusting the current to be measured in the excitation winding through a signal output terminal when the voltage value of the first voltage signal obtained is greater than the voltage value of the second voltage signal.

7. The method according to claim 6, characterized in that The circuit also includes a wirewound resistor; One end of the winding resistor is connected to the excitation winding, and the other end is connected to the first input end of the comparator; and it is used to limit the current in the circuit.

8. The method according to claim 6, characterized in that The circuit also includes a primary winding; The primary winding is wound on the nonlinear magnetic core and is used for converting electrical energy into electromagnetic energy and transferring electrical energy to the secondary winding.

9. The method according to claim 6, characterized in that The signal output terminal of the comparator is used to output a square wave signal.

10. The method according to claim 9, characterized in that The square wave signal is used to excite the nonlinear magnetic core.

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