Implementation method of high-performance current detection device

Abstract

The invention relates to an implementation method of a high-performance current detection device, the structure of the device comprises a Hall current sensor, the Hall current sensor comprises a magnetic core, a primary coil and a feedback coil are wound on the magnetic core, the magnetic core is provided with an air gap, a Hall element is placed in the air gap, and the Hall element is arranged in the magnetic core. The output end of the Hall element is coupled with one end of the feedback coil, the Hall element is used for sensing magnetic flux generated when current to be measured flows through the primary coil and outputting generated compensation current through the other end of the feedback coil, and the compensation current excites the feedback coil to generate reverse magnetic flux so as to offset the magnetic flux generated by the current to be measured; the primary coil is connected with a shunt module, and the shunt module and the input impedance of the primary coil form a shunt circuit which is used for reducing the current to be measured flowing through the primary coil. According to the Hall current sensor, the high-frequency response capability of the Hall current sensor can be improved while high measurement precision is kept.

Description

Technical Field

[0001] The invention relates to the technical field of power electronic measurement, and in particular to a method for realizing a high-performance current detection device. Background Art

[0002] Current measurement is a basic and important measurement task in power electronic systems. At present, the closed-loop Hall current sensor has attracted much attention as a commonly used current measurement method. It uses the magnetic flux generated by the feedback coil to offset the magnetic flux generated by the measured current on the iron core, so that the Hall sensor element always works in a zero flux state, thereby improving the measurement accuracy.

[0003] Traditional closed-loop Hall current sensors usually consist of an iron core, a primary coil, a Hall sensor element, an operational amplifier circuit, a power amplifier circuit, and a feedback coil. The measured current generates a magnetic flux on the iron core through the primary coil, and the Hall element senses the magnetic flux and outputs a voltage signal. After amplification, the voltage drives the feedback coil, so that the magnetic flux generated by the feedback coil offsets the magnetic flux of the primary coil, completing the current measurement.

[0004] This closed-loop design enables the traditional Hall current sensor to achieve high measurement accuracy and linearity. However, due to the existence of the feedback control link, the response speed of the Hall current sensor will be limited by the closed-loop bandwidth. When the frequency of the measured current is high, the closed loop cannot track quickly, which will lead to increased measurement errors. This has become an important factor limiting the application of traditional closed-loop Hall current sensors in high-frequency current measurement situations. Therefore, how to improve the high-frequency response capability of the Hall current sensor while maintaining high measurement accuracy is a technical problem that needs to be solved in this field. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for realizing a high-performance current detection device, which can improve the high-frequency response capability of a Hall current sensor while maintaining high measurement accuracy.

[0006] The technical solution adopted by the present invention to solve its technical problem is: to provide an implementation method of a high-performance current detection device, the structure of which includes a Hall current sensor, the Hall current sensor includes a magnetic core, a primary coil and a feedback coil are wound around the magnetic core, the magnetic core is provided with an air gap, a Hall element is placed in the air gap, the output end of the Hall element is coupled to one end of the feedback coil, used to sense the magnetic flux generated by the current to be measured flowing through the primary coil, and output the generated compensation current through the other end of the feedback coil, the compensation current excites the feedback coil to generate a reverse magnetic flux to offset the magnetic flux generated by the current to be measured; the primary coil is connected to a shunt module, the shunt module and the input impedance of the primary coil form a shunt circuit, used to reduce the current to be measured flowing through the primary coil.

[0007] Furthermore, the shunt module includes a shunt impedance, and the shunt impedance is connected in parallel at both ends of the primary coil.

[0008] Furthermore, the shunt impedance is set to enable the magnitude of the current to be measured after shunting to be within a set range.

[0009] Furthermore, the structure also includes an amplifier circuit, and the output end of the Hall element is coupled to one end of the feedback coil through the amplifier circuit.

[0010] Furthermore, the amplifying circuit includes a first amplifier and a power amplifier which are connected in sequence.

[0011] Furthermore, the first amplifier is an operational amplifier, whose input end is respectively connected to the output end of the Hall element, and whose output end is connected to the input end of the power amplifier.

[0012] Furthermore, the structure also includes a readout module, which includes a feedback output resistor, one end of which is connected to the compensation current and the other end is grounded, so as to convert the compensation current into a detection voltage.

[0013] Furthermore, the readout module also includes a second amplifier connected in parallel across the feedback output resistor, and the second amplifier is used to adjust the detection voltage so that the adjusted detection voltage and the current to be measured before shunting satisfy a set linear relationship.

[0014] Furthermore, the second amplifier is an operational amplifier, and its input terminals are respectively connected to both ends of the feedback output resistor.

[0015] Beneficial Effects

[0016] Due to the adoption of the above technical scheme, the present invention has the following advantages and positive effects compared with the prior art: the present invention introduces a shunt circuit in the measured current loop, so that the current actually passing through the Hall coil is reduced to a small part of the original measured current, thereby reducing the feedback current required by the feedback coil, shortening the response time of the feedback circuit when the number of coil turns remains unchanged, and improving the high-frequency response capability of the entire sensor; the introduced shunt circuit also helps to achieve the derating design of the sensing range of the Hall chip, improve the actual response speed of the Hall chip itself, and the two together can greatly improve the response characteristics of the Hall current sensor; further, by connecting a shunt impedance in parallel at both ends of the primary coil, the shunt impedance and the input impedance of the primary coil form a shunt circuit, ensuring the linear proportional relationship between the measured current after shunting and before shunting, thereby ensuring the measurement accuracy, and the circuit is simple and easy to implement; by adjusting the amplification factor of the amplifier in the feedback loop, the linear relationship between the final measured voltage and the original measured current can be guaranteed, without changing the hardware structure of the traditional Hall current sensor, it can be achieved through software algorithm and circuit adjustment, low cost and easy to implement, suitable for various occasions of measuring high-frequency current, and helpful to improve the high-frequency measurement and control capability of power electronic systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of a high-performance current detection device according to an embodiment of the present invention;

[0018] Figure 2 It is a comparison diagram of the response curves of the high-performance current detection device according to the embodiment of the present invention and the original Hall current sensor;

[0019] Figure 3 It is a circuit equivalent model diagram of a high-performance current detection device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0021] The embodiment of the present invention relates to a method for realizing a high-performance current detection device, the structure of which includes a Hall current sensor, the Hall current sensor including a magnetic core, a primary coil and a feedback coil are wound on the magnetic core, the primary coil and the feedback coil are wound on the same magnetic core and do not overlap each other. An air gap is provided on the magnetic core, a Hall element is placed in the air gap, the output end of the Hall element is coupled to one end of the feedback coil through an amplifier circuit, and is used to sense the magnetic flux generated by the current to be measured flowing through the primary coil, and output the generated compensation current through the other end of the feedback coil, the compensation current can excite the feedback coil to generate a reverse magnetic flux to offset the magnetic flux generated by the current to be measured. The primary coil is connected to a shunt module, and the shunt module and the input impedance of the primary coil form a shunt circuit, which is used to reduce the current to be measured flowing through the primary coil.

[0022] The amplification circuit includes a first amplifier and a power amplifier connected in sequence, which are used to amplify the feedback current and increase its driving capability. The shunt module includes a shunt impedance connected in parallel at both ends of the primary coil, and the shunt impedance can be set to reduce the measured current after shunting to a set interval. In this way, by reducing the current that finally flows through the primary coil, the feedback current amplitude required by the feedback loop can be reduced, and the response speed of the feedback link can be improved without changing the number of coil turns, and ultimately the measurement response capability of the entire sensor to high-frequency current can be improved.

[0023] The output feedback current is converted into a detection voltage through a readout module and can be read out by a measuring instrument. The readout module includes a feedback output resistor and a second amplifier, one end of the feedback output resistor is connected to the compensation current, and the other end is grounded, which is used to convert the compensation current into a detection voltage. The input end of the second amplifier is respectively connected to the two ends of the feedback output resistor, and the detection voltage is adjusted by adjusting the amplification factor of the second amplifier so that it satisfies a set linear relationship with the current to be measured before shunting.

[0024] Specific as Figure 1 As shown, the current detection device in the embodiment is composed of an iron core 1, a primary coil 2, a shunt impedance 3, a Hall current constant current source 4, a Hall element 5, a first operational amplifier circuit 6, a power amplifier circuit 7, a feedback coil 8, a second operational amplifier circuit 9, and a feedback output resistor 10. The input impedance of the primary coil 2 is Z a , the shunt impedance is Z b , it can be in the form of inductance and resistance in series.

[0025] The primary coil 2 and the feedback coil 8 are wound on the annular core 1 without overlapping each other. The current I1 to be measured passes through the parallel Z a and Z b After the shunt circuit performs shunting, the small current I aThe Hall sensor element is installed in the air gap of the iron core 1 to detect the magnetic flux Φ1 generated by the primary coil 2 on the iron core 1 and output the corresponding Hall voltage U according to the magnitude of the induced magnetic flux. H The input end of the operational amplifier circuit 6 is connected to the Hall element 5, receiving the Hall voltage U outputted by the Hall element 5. H After internal operational amplification, the amplified voltage signal is output. The power amplifier circuit 7 is connected to the output end of the operational amplifier circuit 6, and performs power amplification on the voltage signal output by the operational amplifier circuit 6 to generate a feedback current I2 to drive the feedback coil 8. The direction of the magnetic flux φ2 generated by the feedback coil 8 on the iron core is opposite to the direction of the magnetic flux generated by the primary coil 2, and finally cancels the magnetic flux φ1 generated by the primary coil 2 so that the magnetic flux in the magnetic circuit is zero, thereby realizing automatic correction of the Hall element 5.

[0026] By adding Z a and Z b The resistance ratio is adjusted to a smaller ratio, such as Z a :Z b =9:1, which means that the actual current passing through the primary coil is I a Much smaller than the measured current I1, such as only 10% of I1.

[0027] Because I a It is much smaller than I1, so in order to offset the magnetic flux generated by I1 on the iron core, the feedback current I2 required by the feedback coil is also greatly reduced accordingly. When the number of turns of the primary coil and the feedback coil remains unchanged, the amplitude of the feedback current I2 is reduced, and the response time of the feedback circuit will be shortened accordingly, thereby improving the high-frequency response capability of the entire sensor. On the other hand, the input current I a The reduction reduces the air gap working magnetic flux density range and indirectly improves the response speed of the Hall sensor itself.

[0028] The working process of the high-speed Hall current sensor can be Figure 2 Further explanation: Figure 2 The response time curves of the sensor to high-frequency current before and after current adjustment are compared. Before adjustment, the larger feedback current I2 makes the response time longer; after adjustment, the amplitude of I2 is reduced and the response time is significantly shortened, so that the changes of the measured high-frequency current can be tracked more efficiently.

[0029] By measuring the output voltage U' on the feedback output resistor 10 R The feedback current I2 can be obtained, so in order to be able to measure the output voltage U' R The magnitude of the measured current I1 before shunting is obtained, and the two ends of the measurement feedback output resistor 10 are connected to the input end of the second operational amplifier circuit 9 to adjust the amplification factor of the output voltage so that the final measured voltage UR It satisfies the set linear relationship with the measured current I1.

[0030] like Figure 3 The circuit equivalent model shown in the figure is as follows: r1 is the resistance of the primary coil, l1 is the leakage inductance of the primary coil, and the shunt impedance Z b It can be expressed as r3+jωl3, r m is the excitation resistance, l is the excitation inductance, r′2 is the equivalent resistance of the secondary circuit equivalent to the primary circuit, l′2 is the equivalent leakage inductance of the secondary circuit equivalent to the primary circuit, and R′ is the equivalent resistance of the feedback output resistance from the secondary circuit to the primary circuit.

[0031] According to the circuit equivalent model, the input impedance Z of the primary coil is a for,

[0032]

[0033] And there is,

[0034]

[0035] Calculate the current obtained by shunting With the measured current The ratio is,

[0036]

[0037] Where KH is the Hall potential and the excitation current i m The ratio of U H =KH·i m , PID is the first operational amplifier, U′2 is U H PID i m The value is converted to the voltage of the primary circuit (KH·PID·i m )′, C1 is the excitation impedance r m +jωl m and output loop impedance (KH·PID)′+r m +jωl m +R′+r′2+jωl′2 ratio

[0038]

[0039] Formula (3) can be transformed into

[0040]

[0041] Detection output current of the secondary circuit equivalent to the primary circuit for

[0042]

[0043] By adjusting parameters such as (KH·PID)′ and equivalent impedance R′, the real and imaginary parts in equation (4) can satisfy a certain proportional relationship, thereby calculating the constant C1. Substituting the known parameters into equation (5), by adjusting the primary coil resistance r1, the primary coil leakage inductance l1, and the shunt impedance Z b , the real part and the imaginary part in the formula can satisfy a certain proportional relationship, so that the ratio of the measured voltage to the measured current before shunting is calculated to be a constant C2.

[0044] The method ensures a linear proportional relationship between the current obtained after shunting and the current to be measured before shunting, ensures the detection accuracy of the sensor when detecting high-frequency current, and eliminates the influence of excitation impedance on the detection accuracy.

Claims

1. A method for implementing a high-performance current detection device, characterized in that: Its structure includes a Hall current sensor, which includes a magnetic core, a primary coil and a feedback coil are wound around the magnetic core, an air gap is provided on the magnetic core, a Hall element is placed in the air gap, an output end of the Hall element is coupled to one end of the feedback coil, and is used to sense the magnetic flux generated by the current to be measured flowing through the primary coil, and output the generated compensation current through the other end of the feedback coil, and the compensation current excites the feedback coil to generate a reverse magnetic flux to offset the magnetic flux generated by the current to be measured; the primary coil is connected to a shunt module, and the shunt module and the input impedance of the primary coil form a shunt circuit, which is used to reduce the current to be measured flowing through the primary coil.

2. The method according to claim 1, characterized in that The shunt module includes a shunt resistor, and the shunt resistor is connected in parallel at two ends of the primary coil.

3. The method according to claim 2, characterized in that The shunt impedance is set to enable the magnitude of the current to be measured after shunting to be within a set range.

4. The method according to claim 2, characterized in that Its structure also includes an amplifier circuit, and the output end of the Hall element is coupled to one end of the feedback coil through the amplifier circuit.

5. The method according to claim 4, characterized in that The amplifying circuit includes a first amplifier and a power amplifier which are connected in sequence.

6. The method according to claim 5, characterized in that The first amplifier is an operational amplifier, the input end of which is respectively connected to the output end of the Hall element, and the output end of which is connected to the input end of the power amplifier.

7. The method according to claim 1, characterized in that Its structure also includes a readout module, which includes a feedback output resistor, one end of which is connected to the compensation current and the other end is grounded, so as to convert the compensation current into a detection voltage.

8. The method according to claim 7, characterized in that The readout module also includes a second amplifier connected in parallel at both ends of the feedback output resistor, and the second amplifier is used to adjust the detection voltage so that the adjusted detection voltage and the current to be measured before shunting meet a set linear relationship.

9. The method according to claim 8, characterized in that The second amplifier is an operational amplifier, and its input terminals are respectively connected to the two ends of the feedback output resistor.

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