Current sensor and zero drift compensation method

Abstract

This disclosure provides a current sensor and a zero-drift compensation method, applicable to the field of power electronics. The current sensor includes a current measurement circuit, a voltage amplification circuit, and a zero-drift compensation circuit. The current measurement circuit measures the current, and the voltage amplification circuit, connected to the current measurement circuit, amplifies the weak voltage output by the current measurement circuit into an output voltage. The zero-drift compensation circuit, connected to the voltage amplification circuit, outputs a reference voltage to compensate for zero drift in the output voltage. The reference voltage is determined by the output voltage fed back from the voltage amplification circuit. The zero-drift compensation circuit generates a real-time adjusted reference voltage to compensate for zero drift in the output voltage during current measurement and to correct other errors introduced during the current measurement process. Furthermore, the zero-drift compensation method provided in this disclosure reduces manual intervention and lowers costs.

Description

Technical Field

[0001] This disclosure relates to the field of power electronics technology, and in particular to a current sensor and a zero-drift compensation method. Background Technology

[0002] A smart grid is a new type of modern power grid that highly integrates advanced sensing and measurement technologies, information and communication technologies, analysis and decision-making technologies, and automatic control technologies with energy and power technologies and power grid infrastructure. Current is one of the key state variables that needs to be monitored during the operation of a smart grid. By monitoring current, it is possible to achieve real-time monitoring of the smart grid's operating status, rational allocation of power resources, and troubleshooting of transmission line faults. Therefore, current measurement technology is crucial to the development of smart grids.

[0003] Commonly used current measurement techniques primarily utilize tunnel magnetoresistive (TMR) current sensors, which offer advantages such as small size, high sensitivity, and high accuracy. However, TMR current sensors often suffer from zero drift in their output voltage due to errors introduced during manufacturing and operational deviations. Related techniques typically address this issue by pre-sampling and storing the zero drift in the output voltage before the TMR current sensor is put into use, and then subtracting the offset from the output signal.

[0004] In the process of realizing the concept disclosed herein, the inventors discovered at least the following problems in the related technology: the zero drift compensation of this method is performed before the TMR current sensor is put into use, the compensation amount is fixed, the zero drift compensation lacks real-time performance, it cannot immediately correct other errors introduced during the current measurement process, and the method is complicated to operate, requires manual intervention, and is costly. Summary of the Invention

[0005] In view of the above problems, this disclosure provides a current sensor and a zero-drift compensation method.

[0006] According to a first aspect of this disclosure, a current sensor is provided, comprising a current measuring circuit, a voltage amplification circuit, and a zero-drift compensation circuit. The input terminal of the current measuring circuit is connected to a first positive power supply; the positive voltage output terminal of the current measuring circuit is connected to the positive input terminal of the voltage amplification circuit; the negative voltage output terminal of the current measuring circuit is connected to the negative input terminal of the voltage amplification circuit; the compensation input terminal of the voltage amplification circuit is connected to the output terminal of the zero-drift compensation circuit, and the output terminal of the voltage amplification circuit is used to output an output voltage; the positive power supply input terminal of the zero-drift compensation circuit is connected to a second positive power supply; the negative power supply input terminal of the zero-drift compensation circuit is connected to the negative power supply; and the output terminal of the zero-drift compensation circuit is used to output a reference voltage to compensate for zero drift in the output voltage. The reference voltage is determined by the output voltage fed back from the voltage amplification circuit.

[0007] According to an embodiment of this disclosure, the zero-drift compensation circuit includes a voltage divider circuit and a voltage follower circuit. The voltage divider circuit is connected to the voltage follower circuit. The voltage divider circuit is used to obtain the reference voltage, and the voltage follower circuit is used to transmit the reference voltage to the compensation input terminal of the voltage amplifier circuit.

[0008] According to an embodiment of this disclosure, the voltage divider circuit includes a resistor array and a switching system. By controlling the switching system, the resistance value of the resistor array is adjusted, thereby regulating the reference voltage.

[0009] According to an embodiment of this disclosure, the voltage divider circuit has a symmetrical structure, including a first voltage divider circuit and a second voltage divider circuit. The voltage divider circuit includes an intermediate terminal. The first terminal of the first voltage divider circuit is connected to the second positive power supply, and the second terminal of the first voltage divider circuit is connected to the intermediate terminal. The first terminal of the second voltage divider circuit is connected to the negative power supply, and the second terminal of the second voltage divider circuit is connected to the intermediate terminal.

[0010] According to embodiments of this disclosure, the voltage divider circuit is a multiplexed structure. The first voltage divider circuit includes a first resistor array and a first switching system, and the second voltage divider circuit includes a second resistor array and a second switching system. The resistors in the first resistor array are connected in series, and the first switching system is used to control the conduction and disconnection of the resistors in the first resistor array. The resistors in the second resistor array are connected in series, and the second switching system is used to control the conduction and disconnection of the resistors in the second resistor array.

[0011] According to an embodiment of this disclosure, the non-inverting input terminal of the voltage follower circuit is connected to the intermediate terminal, the inverting input terminal of the voltage follower circuit is connected to the output terminal of the voltage follower circuit, and the output terminal of the voltage follower circuit is connected to the compensation input terminal of the voltage amplifier circuit.

[0012] According to an embodiment of this disclosure, the current sensor is a TMR current sensor, which includes four magnetoresistors.

[0013] According to an embodiment of this disclosure, the current sensor further includes a voltage detection circuit, the input terminal of which is connected to the output terminal of the voltage amplification circuit, and the voltage detection circuit is used to detect the output voltage fed back by the voltage amplification circuit.

[0014] According to an embodiment of this disclosure, the current sensor further includes a control circuit, the input terminal of which is connected to the output terminal of the voltage detection circuit, and the output terminal of which is connected to the zero drift compensation circuit.

[0015] A second aspect of this disclosure provides a zero-drift compensation method. The zero-drift compensation method includes: measuring a current through a current measuring circuit and outputting a weak voltage linearly related to the current; amplifying the weak voltage into an output voltage through a voltage amplification circuit; determining whether zero drift exists in the output voltage through a voltage detection circuit; if zero drift exists in the output voltage, a control circuit generates a compensation signal, and a zero-drift compensation circuit outputs a reference voltage based on the compensation signal, the reference voltage being used to compensate for zero drift in the output voltage; if zero drift does not exist in the output voltage, the control circuit generates an output signal to output the output voltage.

[0016] According to the current sensor and zero-drift compensation method provided in this disclosure, a current measuring circuit measures the current and outputs a weak voltage linearly related to the current; a voltage amplification circuit amplifies this weak voltage into an output voltage; and a zero-drift compensation circuit outputs a reference voltage to compensate for zero drift in the output voltage. This reference voltage is determined by the output voltage fed back from the voltage amplification circuit. Therefore, the zero-drift compensation circuit can generate a real-time adjusted reference voltage to compensate for zero drift in the output voltage during current measurement by the current sensor, and can also correct other errors introduced during current measurement in real time. Furthermore, the zero-drift compensation method provided in this disclosure reduces manual intervention, lowers costs, and improves the operating efficiency and reliability of the smart grid. Attached Figure Description

[0017] The foregoing contents, as well as other objects, features, and advantages of this disclosure, will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0018] Figure 1 A schematic diagram of the equivalent Wheatstone full-bridge circuit for a single TMR magnetic sensing unit is shown.

[0019] Figure 2 A current sensor provided according to an embodiment of the present disclosure is illustrated schematically;

[0020] Figure 3 A schematic diagram of a zero-drift compensation circuit provided according to an embodiment of the present disclosure is shown.

[0021] Figure 4 A schematic diagram of a voltage divider circuit provided according to an embodiment of the present disclosure is shown.

[0022] Figure 5 The schematic diagram illustrates a workflow of a current sensor provided according to embodiments of the present disclosure; and

[0023] Figure 6 A flowchart illustrating a zero-drift compensation method according to an embodiment of the present disclosure is shown. Detailed Implementation

[0024] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0026] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0027] With the continuous advancement of the information age, the power grid sector has ushered in a time of comprehensive upgrading, giving rise to the concept of smart grids. Smart grids are built upon integrated, high-speed, two-way communication networks, and through the application of advanced sensing and measurement technologies, equipment technologies, control methods, and decision support system technologies, aim to achieve multiple goals for the power grid, including reliability, safety, economy, efficiency, environmental friendliness, and operational safety.

[0028] Power systems generate a wide variety of data, making sensors indispensable as key technological tools for collecting and transmitting this data. Advanced sensing technology is also a crucial technological foundation for smart grids. In power systems, current is one of the most important state variables, making real-time and accurate measurement of current of great significance. Real-time current monitoring helps maintain the stability of the power system, ensuring that the current remains within safe limits, thereby improving the stability and security of the power system.

[0029] To achieve accurate current measurement, various current sensors are widely used in power systems, such as current transformers, Rogowski coils, shunts, fluxgate current sensors, Hall effect current sensors, and magnetoresistive current sensors. Magnetoresistive sensors are a new type of current sensor, primarily measuring current through the giant magnetoresistance (GMR) or TMR effect. Compared to traditional current transformers, magnetoresistive sensors can measure a wider range of magnetic field frequencies. Compared to Hall effect current sensors, magnetoresistive sensors are smaller, more sensitive, and exhibit better temperature stability. Compared to fiber optic current sensors and fluxgate current sensors, magnetoresistive sensors are simpler in structure, lower in cost, and easier to deploy on a large scale. With in-depth research into the magnetoresistive effect, magnetoresistive sensors have demonstrated strong competitiveness and profound application potential in power systems, especially TMR-based current sensors, which have become a focus of current power grid applications.

[0030] According to the Biot-Savart law, the magnetic field generated by a long, straight current-carrying conductor at a fixed point in space is directly proportional to the current flowing through the conductor. A TMR (Transient Magnetic Resonance) sensing element is essentially a resistive device whose resistance changes with the magnetic field. Within a certain magnetic field range, the resistance of a TMR sensor is linearly related to the magnitude of the magnetic field. Based on this characteristic, a TMR current sensor can be constructed. By keeping the position of the TMR sensor chip relative to the long, straight current-carrying conductor constant, the output voltage of the TMR sensor maintains a linear relationship with the current in the conductor, thus achieving accurate current measurement.

[0031] The core sensing element of a TMR current sensor is one or more multilayer TMR magnetic sensing units based on thin-film resistor technology. The equivalent Wheatstone full-bridge circuit structure of a single TMR magnetic sensing unit is as follows: Figure 1 As shown. This equivalent Wheatstone full-bridge circuit includes four magnetoresistors; more specifically, the magnetoresistors of the TMR sensing element include a first magnetoresistor R1, a second magnetoresistor R2, a third magnetoresistor R3, and a fourth magnetoresistor R4. By setting the magnetization directions of the reference layers for the different magnetoresistors to be offset by 180°, the pinning directions of the first magnetoresistor R1 and the fourth magnetoresistor R4 are the same, and opposite to the pinning directions of the second magnetoresistor R2 and the third magnetoresistor R3.

[0032] When an external magnetic field is applied, the resistances of the first magnetoresistor R1, the fourth magnetoresistor R4, the second magnetoresistor R2, and the third magnetoresistor R3 will change under the influence of the magnetic field. The resistances of the first magnetoresistor R1 and the fourth magnetoresistor R4 will increase, while the resistances of the second magnetoresistor R2 and the third magnetoresistor R3 will decrease. Therefore, when the external magnetic field changes,

[0033] Positive pressure output V O+ It can be represented as:

[0034]

[0035] Among them, V O+ This is the positive voltage output of the equivalent Wheatstone full-bridge circuit; V DD R1 is the input power supply for the equivalent Wheatstone full-bridge circuit; R2 is the second magnetoresistive resistor; R4 is the fourth magnetoresistive resistor; ΔR2 is the resistance change of the second magnetoresistive resistor R2; ΔR4 is the resistance change of the fourth magnetoresistive resistor R4.

[0036] Negative voltage output V O- It can be represented as:

[0037]

[0038] Among them, V O- This is the negative voltage output of the equivalent Wheatstone full-bridge circuit; R3 is the third magnetoresistive resistor; R1 is the first magnetoresistive resistor; ΔR3 is the resistance change of the third magnetoresistive resistor R3; ΔR1 is the resistance change of the first magnetoresistive resistor R1.

[0039] Ideally, disregarding deviations in the manufacturing process and structure of the magnetoresistive resistors, the basic resistance values ​​of the first magnetoresistive resistor R1, the second magnetoresistive resistor R2, the third magnetoresistive resistor R3, and the fourth magnetoresistive resistor R4 are all equal, i.e.:

[0040] R1=R2=R3=R4=R (3)

[0041] Furthermore, under ideal conditions, when an external magnetic field is applied, the magnitudes of the changes in resistance values ​​of the first magnetoresistance R1, the fourth magnetoresistance R4, the second magnetoresistance R2, and the third magnetoresistance R3 are equal, that is:

[0042] ΔR1=ΔR2=ΔR3=ΔR4=ΔR (4)

[0043] Therefore:

[0044] R1+ΔR1=R4+ΔR4=R+ΔR (5)

[0045] R2-ΔR2=R3-ΔR3=R-ΔR (6)

[0046] The differential output signal can be represented as:

[0047]

[0048] Among them, V O This is the differential output signal of the equivalent Wheatstone full-bridge circuit.

[0049] The above differential output signal V O While exhibiting good linearity and high sensitivity, in practice, due to errors introduced during the manufacturing process and deviations during operation, the resistance values ​​of the magnetoresistors in the four bridge circuits are not entirely equal when the external magnetic field is zero (i.e., no current input). Therefore, the TMR current sensor output will experience zero-point drift, or zero drift for short, meaning that the output voltage is not zero when the input current is zero.

[0050] Related technologies often address zero drift by sampling the output voltage multiple times before the TMR current sensor is put into use, obtaining the offset based on the sampling results, storing the offset, and subtracting the offset from the output signal. However, this method of zero drift compensation is performed before the TMR current sensor is put into use, the compensation amount is fixed, and the zero drift compensation lacks real-time capability, failing to immediately correct for other errors introduced during current measurement. Moreover, this method is complex to operate, requires manual intervention, and is costly.

[0051] In order to at least partially solve the technical problems existing in the related art, embodiments of this disclosure provide a current sensor and a zero-drift compensation method that can be applied to the field of power electronics technology.

[0052] Figure 2 A current sensor provided according to an embodiment of this disclosure is illustrated schematically. For example... Figure 2 As shown, the current sensor 100 includes a current measurement circuit 10, a voltage amplification circuit 20, and a zero-drift compensation circuit 30. The input terminal of the current measurement circuit 10 is connected to the first positive power supply V. DD1 The positive voltage output terminal of the current measuring circuit 10 is connected to the positive input terminal of the voltage amplification circuit 20, so as to amplify the positive voltage output V. O+The signal is transmitted to the voltage amplifier circuit 20. The negative voltage output terminal of the current measuring circuit 10 is connected to the negative input terminal of the voltage amplifier circuit 20 to output the negative voltage V. O- The signal is transmitted to voltage amplifier circuit 20. The compensation input terminal of voltage amplifier circuit 20 is connected to the output terminal of zero-drift compensation circuit 30. The output terminal of voltage amplifier circuit 20 is used to output voltage V. out Output. The positive power supply input terminal of the zero-drift compensation circuit 30 is connected to the second positive power supply V. DD2 Connected, the negative power supply input terminal of the zero-drift compensation circuit 30 is connected to the negative power supply V. Ss The output terminal of the zero-drift compensation circuit 30, connected in series, is used to output the output voltage V. out The reference voltage V used for zero drift compensation ref Reference voltage V ref The output voltage V is fed back through the voltage amplifier circuit 20. out It's confirmed.

[0053] Current sensors in smart grids are mostly used for detecting weak currents, which are mostly in the mA range, and their output voltages are mostly in the mV range. A current measurement circuit measures the weak current and outputs a weak voltage that is linearly related to the weak current. Therefore, to facilitate the detection of weak voltages, the current measurement circuit 10 provided in this disclosure has a positive voltage output V. O+ and negative voltage output V O- Typically, the voltage is amplified by voltage amplifier circuit 20 to increase the weak voltage to an output voltage V. out And will include positive pressure output V O+ and negative voltage output V O- The differential signal is converted into a single-ended signal. The output voltage V of voltage amplifier circuit 20 is... out According to the reference voltage V ref The change, namely the output voltage V of the voltage amplifier circuit 20 out The formula is:

[0054] V out =G*(V o+ -V o- )+V ref (8)

[0055] Among them, V oUt V is the output voltage of voltage amplifier circuit 20; G is the gain of voltage amplifier circuit 20; V O+ This is the positive voltage output of the current measurement circuit 10; V O- This is the negative voltage output of the current measuring circuit 10; V ref This is the reference voltage output by the zero-drift compensation circuit 30.

[0056] In practice, due to errors introduced during the manufacturing process of magnetoresistive sensors and deviations during operation, the output voltage V of the current sensor will vary during current measurement. out Zero drift exists. In this case of zero drift, the output voltage V of voltage amplifier circuit 20... out The formula is:

[0057] V out =G*(V o+ -V o- )+V DC +V ref (9)

[0058] Among them, V DC The DC component introduced by zero drift.

[0059] The current sensor 100 provided in this embodiment of the present disclosure, based on the above formula, uses a zero-drift compensation circuit 30 to adjust the reference voltage V. ref Adjust the reference voltage V. ref The output is fed into voltage amplifier circuit 20 to amplify the output voltage V. out Zero drift is compensated so that when the input current is zero, the output voltage V out It is also zero. The reference voltage V is also zero. ref The output voltage V is fed back through the voltage amplifier circuit 20. out It is certain. Therefore, the zero-drift compensation circuit 30 can adjust the output voltage V fed back by the voltage amplifier circuit 20. out Generates a reference voltage V that can be adjusted in real time. ref During the current measurement process by the current sensor 100, the output voltage V is adjusted. out This method provides real-time compensation for zero drift and real-time correction for other errors introduced during current measurement. Furthermore, the zero drift compensation method disclosed herein reduces manual intervention and improves the operational efficiency and reliability of the smart grid.

[0060] Figure 3 A schematic diagram of a zero-drift compensation circuit provided according to an embodiment of the present disclosure is shown. Figure 3 As shown, the zero-drift compensation circuit 30 includes a voltage divider circuit 31 and a voltage follower circuit 32. The voltage divider circuit 31 is connected to the voltage follower circuit 32. The voltage divider circuit 31 is used to obtain an adjustable reference voltage V. ref The voltage follower circuit 32 is used to convert the reference voltage V ref The signal is transmitted to the compensation input terminal of the voltage amplifier circuit 20 to adjust the output voltage V. out The zero drift is compensated.

[0061] Figure 4A schematic diagram of a voltage divider circuit provided according to an embodiment of the present disclosure is shown. The voltage divider circuit 31 includes a resistor array and a switching system. By controlling the switching system, the resistance value of the resistor array is adjusted, thereby regulating the reference voltage V. ref The voltage value. For example, the reference voltage V is adjusted by controlling the closing and opening of the switching system to adjust the resistance value of the resistor array. ref The voltage value.

[0062] According to embodiments of this disclosure, the voltage divider circuit 31 has a symmetrical structure. The symmetrical structure of the voltage divider circuit 31 can reduce measurement errors, ensure circuit matching, and thus ensure better stability and reliability of the circuit under different conditions.

[0063] The voltage divider circuit 31 includes a first voltage divider circuit 311, a second voltage divider circuit 312, and an intermediate terminal MID. The first terminal of the first voltage divider circuit 311 is connected to the second positive power supply V. DD2 The first voltage divider circuit 311 is connected to the second terminal MID, and the second voltage divider circuit 312 is connected to the negative power supply V. SS The second terminal of the second voltage divider circuit 312 is connected to the middle terminal MID.

[0064] According to embodiments of this disclosure, the voltage divider circuit 31 is a multiplexed structure. The multiplexed structure of the voltage divider circuit 31 can effectively reduce the circuit area, which is beneficial for achieving a more compact and space-saving layout in integrated circuit design. Furthermore, the multiplexed structure of the voltage divider circuit 31 can improve the utilization efficiency of the resistors, allowing adjustment of the entire resistor array by changing a single switching state. The first voltage divider circuit 311 includes a first resistor array R. a and the first switching system SW a The second voltage divider circuit 312 includes a second resistor array Rb and a second switching system SW. b The first resistor array R a The resistors in the first switching system SW are connected in series. a Used to control the first resistor array R a The switching of the resistors in the second resistor array involves their on / off states. The resistors Rb in the second resistor array are connected in series. The second switching system SW... b Used to control the switching on and off of resistors in the second resistor array Rb.

[0065] Reference voltage V ref The formula can be expressed as:

[0066]

[0067] Among them, V ref R is the reference voltage; a This is the first resistor array; R bFor the second resistor array; V DD2 For the second power supply; V SS It is a negative power source.

[0068] Therefore, through the first switching system SW a Adjust the first resistor array R a The resistance value is determined by the second switching system SW. b Adjust the second resistor array R b The resistance value is then used to adjust the reference voltage V. ref The voltage value. And the reference voltage V ref The voltage value can be achieved at the second power supply V DD2 The voltage value and negative power supply V SS The voltage value is adjusted within a certain range to fully meet the voltage range used for zero drift compensation, thereby enabling the zero drift compensation circuit 30 to achieve the desired output voltage V. out The real-time complete zero-drift compensation ensures that when the input current is zero, the output voltage V... out It stabilizes at 0V.

[0069] For example, the first resistor array R a It can include a first resistor 'R1', a second resistor 'R2', ..., an Nth resistor 'R' N ', First switch system SW a Including the first switch 'SW1', the second switch 'SW2', ..., the Nth switch 'SW' N The second resistor array Rb may include a first resistor "R1", a second resistor "R2", ..., an Nth resistor "R". N "Second switch system SW" b Including the first switch "SW1", the second switch "SW2", ..., the Nth switch "SW N ".

[0070] First resistor array R a The first resistor 'R1', the second resistor 'R2', ..., and the Nth resistor 'R' in the diagram N The connection method is series, and the first terminal of the first resistor 'R1' is connected to the second positive power supply V. DD2 Connected, the Nth resistor'R N The second terminal is connected to the middle terminal MID. The second resistor array R... b The first resistor "R1", the second resistor "R2", ..., and the Nth resistor "R" in the diagram. N The connection method is series, and the first terminal of the first resistor "R1" is connected to the negative power supply V. SS Connected, the Nth resistor "R" NThe second end of the symbol is connected to the middle end MID.

[0071] First switching system SW a The first terminal of the first switch 'SW1' in the first resistor array R is connected to the first resistor array R. a The first terminal of the first resistor 'R1' is connected to the first switch system SW. a The second terminal of the first switch 'SW1' is connected to the middle terminal MID, and the first switch system SW a The first terminal of the second switch 'SW2' in the first resistor array R a The first terminal of the second resistor 'R2' is connected to the first switching system SW. a The second terminal of the second switch 'SW2' is connected to the middle terminal MID, ..., the first switch system SW a The Nth switch 'SW' in N The first end of ' is connected to the first resistor array R a The Nth resistor 'R N The first end is connected, the first switch system SW a The Nth switch 'SW' in N The second end is connected to the middle end MID.

[0072] Second switching system SW b The first terminal of the first switch "SW1" in the second resistor array R is connected to the first terminal of the second resistor array R. b The first terminal of the first resistor "R1" is connected to the second switch system SW. b The second terminal of the first switch "SW1" is connected to the middle terminal MID, and the second switch system SW b The first terminal of the second switch "SW2" is connected to the second resistor array R. b The first terminal of the second resistor "R2" is connected to the second switching system SW. b The second terminal of the second switch "SW2" is connected to the middle terminal MID, ..., the second switch system SW b The Nth switch in the "SW" N The first terminal of “RN” is connected to the first terminal of the Nth resistor “RN” in the second resistor array Rb, and the second switching system SW b The Nth switch in the "SW" N The second end of the symbol is connected to the middle end MID.

[0073] According to an embodiment of this disclosure, the non-inverting input terminal of the voltage follower circuit 32 is connected to the intermediate terminal MID, the inverting input terminal of the voltage follower circuit 32 is connected to the output terminal of the voltage follower circuit 32, and the output terminal of the voltage follower circuit 32 is connected to the compensation input terminal of the voltage amplifier circuit 20.

[0074] According to an embodiment of this disclosure, the current sensor 100 is a TMR current sensor, which includes four magnetoresistors.

[0075] Figure 5 A schematic diagram illustrating the operation of a current sensor provided according to embodiments of the present disclosure is shown. Figure 5 As shown, the current sensor 100 may include a current measurement circuit 10, a voltage amplifier circuit 20, and a zero-drift compensation circuit 30, as well as a voltage detection circuit 40. The input terminal of the voltage detection circuit 40 is connected to the output terminal of the voltage amplifier circuit 20, and the voltage detection circuit 40 is used to detect the output voltage V fed back by the voltage amplifier circuit 20. out .

[0076] According to embodiments of this disclosure, such as Figure 5 As shown, the current sensor 100 may also include a control circuit 50, the input terminal of which is connected to the output terminal of the voltage detection circuit 40, and the output terminal of the control circuit 50 is connected to the zero drift compensation circuit 30.

[0077] Therefore, the current in the long DC conductor is measured by the current measuring circuit 10. This long DC conductor will generate a magnetic field at a fixed point in space that is proportional to the current passing through the conductor. The resistance value of the magnetoresistive resistor in the current measuring circuit 10 is linearly related to the magnitude of the magnetic field, and thus the output voltage V of the current measuring circuit 10 is... out A linear relationship is maintained between the current and the current in a long, straight current-carrying conductor, thus enabling accurate current measurement. It is important to note that the output voltage V of the current measurement circuit 10... out This is typically a weak voltage, which needs to be amplified by the voltage amplifier circuit 20, and the amplified output voltage V is... out Output.

[0078] Voltage detection circuit 40 can detect the output voltage V fed back by voltage amplifier circuit 20. out When the voltage detection circuit 40 detects the output voltage V out In the case of zero drift, that is, when the input current is zero, the output voltage V out When the voltage is not zero, the voltage detection circuit 40 sends a control signal to the control circuit 50, causing the control circuit 50 to generate a compensation signal. The zero-drift compensation circuit 30 can then output a reference voltage V for zero-drift compensation based on the compensation signal. ref More specifically, the zero-drift compensation circuit 30, based on a compensation signal, adjusts the resistance value of the resistor array by controlling the closing and opening of the switching system, thereby adjusting the reference voltage V. ref The voltage value is adjusted so that the adjusted reference voltage V ref It can be used to measure the output voltage V outZero drift is compensated so that when the input current is zero, the output voltage V out It is also zero.

[0079] When the voltage detection circuit 40 detects the output voltage V out In the absence of zero drift, i.e., when the input current is zero, the output voltage V out When the voltage is also zero, the voltage detection circuit 40 sends an output signal to the control circuit 50, causing the output voltage V to... out It can be output.

[0080] Figure 6 A flowchart illustrating a zero-drift compensation method according to an embodiment of the present disclosure is shown schematically. Figure 6 As shown, the zero drift compensation method 600 includes operations S601 to S605.

[0081] When operating the S601, the current is measured by the current measurement circuit, and a weak voltage that is linearly related to the current is output.

[0082] When operating the S602, the weak voltage is amplified into an output voltage through a voltage amplifier circuit.

[0083] When operating the S603, the voltage detection circuit determines whether the output voltage has zero drift.

[0084] In the event of zero drift in the output voltage, operation S604 is executed, the control circuit generates a compensation signal, and the zero drift compensation circuit outputs a reference voltage based on the compensation signal. The reference voltage is used to compensate for the zero drift in the output voltage.

[0085] If there is no zero drift in the output voltage, operation S605 is executed, and the control circuit generates an output signal to output the output voltage.

[0086] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0087] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A current sensor, comprising a current measuring circuit, a voltage amplification circuit, and a zero-drift compensation circuit, wherein, The input terminal of the current measuring circuit is connected to the first positive power supply, the positive voltage output terminal of the current measuring circuit is connected to the positive input terminal of the voltage amplification circuit, and the negative voltage output terminal of the current measuring circuit is connected to the negative input terminal of the voltage amplification circuit. The compensation input terminal of the voltage amplifier circuit is connected to the output terminal of the zero drift compensation circuit, and the output terminal of the voltage amplifier circuit is used to output the output voltage. The positive power input terminal of the zero drift compensation circuit is connected to the second positive power supply, the negative power input terminal of the zero drift compensation circuit is connected to the negative power supply, and the output terminal of the zero drift compensation circuit is used to output a reference voltage to compensate for the zero drift in the output voltage. The reference voltage is determined by the output voltage fed back by the voltage amplifier circuit. The zero-drift compensation circuit includes a voltage divider circuit and a voltage follower circuit. The voltage divider circuit is connected to the voltage follower circuit. The voltage divider circuit is used to obtain the reference voltage, and the voltage follower circuit is used to transmit the reference voltage to the compensation input terminal of the voltage amplifier circuit. The voltage divider circuit has a symmetrical structure and includes a first voltage divider circuit and a second voltage divider circuit. The voltage divider circuit includes a middle terminal. The first terminal of the first voltage divider circuit is connected to the second positive power supply, and the second terminal of the first voltage divider circuit is connected to the middle terminal. The first terminal of the second voltage divider circuit is connected to the negative power supply, and the second terminal of the second voltage divider circuit is connected to the middle terminal. The voltage divider circuit is a multiplexed structure. The first voltage divider circuit includes a first resistor array and a first switching system, and the second voltage divider circuit includes a second resistor array and a second switching system. The resistors in the first resistor array are connected in series, and the first switching system is used to control the conduction and disconnection of the resistors in the first resistor array. The resistors in the second resistor array are connected in series, and the second switching system is used to control the conduction and disconnection of the resistors in the second resistor array; The formula for the reference voltage Vref is expressed as: ; Among them, R a This is the first resistor array; R b For the second resistor array; V DD2 For the second power supply; V SS It is a negative power source; The non-inverting input terminal of the voltage follower circuit is connected to the intermediate terminal, the inverting input terminal of the voltage follower circuit is connected to the output terminal of the voltage follower circuit, and the output terminal of the voltage follower circuit is connected to the compensation input terminal of the voltage amplifier circuit.

2. The current sensor according to claim 1, wherein, The voltage divider circuit includes a resistor array and a switching system. By controlling the switching system, the resistance value of the resistor array is adjusted, thereby regulating the reference voltage.

3. The current sensor according to claim 1, wherein, The current sensor is a TMR current sensor, which includes four magnetoresistors.

4. The current sensor according to claim 1, wherein the current sensor further comprises a voltage detection circuit; the input terminal of the voltage detection circuit is connected to the output terminal of the voltage amplification circuit, and the voltage detection circuit is used to detect the output voltage fed back by the voltage amplification circuit.

5. The current sensor according to claim 4, wherein the current sensor further comprises a control circuit; the input terminal of the control circuit is connected to the output terminal of the voltage detection circuit, and the output terminal of the control circuit is connected to the zero drift compensation circuit.

6. A zero-drift compensation method, applied to the current sensor according to any one of claims 1 to 5, comprising: The current is measured by a current measuring circuit, and a weak voltage that is linearly related to the current is output. The weak voltage is amplified into an output voltage using a voltage amplification circuit; The voltage detection circuit determines whether zero drift exists in the output voltage. In the event of zero drift in the output voltage, the control circuit generates a compensation signal, and the zero drift compensation circuit outputs a reference voltage based on the compensation signal. The reference voltage is used to compensate for the zero drift in the output voltage. If there is no zero drift in the output voltage, the control circuit generates an output signal to output the output voltage.

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