Implementation method of high-performance voltage detection device

Abstract

The invention relates to an implementation method of a high-performance voltage detection device, the structure of the device comprises a Hall voltage sensor, the Hall voltage 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 by the primary coil through voltage to be measured and outputting generated compensation voltage through the other end of the feedback coil, and the compensation voltage excites the feedback coil to generate reverse magnetic flux so as to offset the magnetic flux generated by the voltage to be measured; the primary coil is connected with a voltage division module, and the voltage division module and the input inductive impedance of the primary coil form a voltage division circuit which is used for reducing the voltage to be measured applied to the two ends of the primary coil. According to the invention, the high-frequency response capability of the Hall voltage sensor can be improved, and high measurement precision can be maintained.

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 voltage detection device. Background Art

[0002] At present, the detection of bus voltage and three-phase voltage in power electronic devices such as industrial motor servo drives is generally detected directly through resistance voltage drop, which cannot achieve electrical insulation isolation between strong and weak electricity, bringing hidden dangers to the safe operation of the system. The main reason is that the existing isolated voltage sensors have problems in response speed, accuracy and adaptability. Specifically, from the analysis of the three main types of isolated voltage sensors currently available: the first is the voltage transformer, which has a high response characteristic, but cannot measure DC voltage, and the detection range of different frequencies varies greatly and has poor adaptability; the second is based on the implementation of isolated operational amplifiers. This type of sensor can measure AC and DC voltages with high measurement accuracy, but the disadvantage is low response speed; the third is the Hall voltage sensor, which measures the voltage applied to the primary winding by collecting the resistor voltage connected in series in the secondary winding of the closed-loop current sensor. The Hall voltage sensor can also measure AC and DC voltages, but the measurement accuracy and response speed need to be improved, and it is difficult to meet the real-time voltage detection requirements of high-frequency power electronic devices. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for realizing a high-performance voltage detection device, which can improve the high-frequency response capability of a Hall voltage sensor while maintaining high measurement accuracy.

[0004] The technical solution adopted by the present invention to solve its technical problem is: to provide an implementation method of a high-performance voltage detection device, the structure of which includes a Hall voltage sensor, the Hall voltage sensor includes 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, 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 primary coil due to the voltage to be measured, and output the generated compensation voltage through the other end of the feedback coil, the compensation voltage excites the feedback coil to generate a reverse magnetic flux to offset the magnetic flux generated by the voltage to be measured; the primary coil is connected to a voltage divider module, the voltage divider module and the input inductive impedance of the primary coil form a voltage divider circuit, used to reduce the voltage to be measured applied to both ends of the primary coil.

[0005] Furthermore, the voltage divider module includes a current limiting resistor, a first end of the current limiting resistor is connected to one end of the primary coil, and two ends of the initial voltage to be measured are respectively connected to the second end of the current limiting resistor and the other end of the primary coil, and the voltage to be measured is generated after voltage division.

[0006] Furthermore, the voltage divider module also includes a first voltage divider resistor, a second voltage divider resistor and a voltage follower, the second end of the first voltage divider resistor is respectively connected to the first end of the second voltage divider resistor and the input end of the voltage follower, the output end of the voltage follower is connected to the second end of the current limiting resistor, and the two ends of the initial voltage to be measured are respectively connected to the first end of the first voltage divider resistor and the second end of the second voltage divider resistor.

[0007] 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.

[0008] Furthermore, the amplifying circuit includes a first amplifier and a power amplifier which are connected in sequence.

[0009] 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.

[0010] Furthermore, the structure also includes a readout module, which includes a feedback output inductive impedance, one end of which is connected to the compensation voltage and the other end is grounded, so as to convert the compensation voltage into a detection voltage.

[0011] Furthermore, the readout module also includes a second amplifier connected in parallel across the feedback output inductive impedance, and the second amplifier is used to adjust the detection voltage so that the adjusted detection voltage satisfies a set linear relationship with the initial voltage to be measured.

[0012] Furthermore, the second amplifier is an operational amplifier, and its input terminals are respectively connected to two ends of the feedback output inductive impedance.

[0013] Beneficial Effects

[0014] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: the present invention introduces a voltage divider circuit into the measured voltage loop, so that the voltage actually passing through the Hall coil is reduced to a small part of the original measured voltage, and then the inductance of the primary winding and the feedback winding can be reduced by reducing the number of turns of the primary winding and the feedback coil, which is not only conducive to shortening the response time of the feedback circuit and improving the high-frequency response capability of the entire sensor, but also conducive to reducing the power consumption of the sensor; the introduced voltage divider circuit is also helpful to realize the derating design of the sensing range of the Hall chip and improve the actual response speed of the Hall chip itself, and the two work together The response characteristics of the Hall voltage sensor can be greatly improved; further, the feedback output inductive impedance is connected in series in the secondary winding, so that the ratio of the feedback output inductive impedance to the input inductive impedance of the voltage sensor is a constant, which improves the detection 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 voltage can be guaranteed, and there is no need to change the hardware structure of the traditional Hall voltage sensor. It can be achieved through software algorithms and circuit adjustments, with low cost and easy implementation, and is suitable for various occasions for measuring high-frequency voltages, and helps to improve the high-frequency and high-precision measurement and control capabilities of power electronic systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 1 is a schematic diagram of the structure of a high-performance voltage detection device according to Example 1 of an embodiment of the present invention;

[0016] Figure 2 is a schematic structural diagram of a high-performance voltage detection device according to Example 2 of an embodiment of the present invention;

[0017] Figure 3 is an equivalent circuit diagram of Example 1 in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] 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.

[0019] The embodiment of the present invention relates to a method for realizing a high-performance voltage detection device, the structure of which includes a Hall voltage sensor, the Hall voltage sensor includes a magnetic core, a primary coil and a feedback coil are wound on the magnetic core, and the primary coil and the feedback coil are wound on the same magnetic core. An air gap is provided on the magnetic core, and 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, which is used to sense the magnetic flux generated by the primary coil caused by the voltage to be measured, and output the generated compensation voltage through the other end of the feedback coil. The compensation voltage can excite the feedback coil to generate a reverse magnetic flux to offset the magnetic flux generated by the voltage to be measured. Among them, the amplifier circuit includes a first amplifier and a power amplifier connected in sequence, which are used to amplify the feedback voltage to increase its driving ability. The primary coil is connected to a voltage divider module, and the voltage divider module and the input inductive impedance of the primary coil form a voltage divider circuit, which is used to reduce the voltage to be measured at both ends of the primary coil. The voltage divider module includes a current limiting resistor connected in series at one end of the primary coil. Under the premise of ensuring the normal operation of the Hall element, by increasing the size of the current limiting resistor, the electromagnetic time constant is reduced, the response speed of the feedback link is improved, and finally the measurement response capability of the entire sensor to high-frequency voltage is improved.

[0020] In some embodiments, because the voltage to be measured becomes smaller after voltage division, the response speed can be further improved by reducing the number of coil turns. The closed-loop Hall voltage sensor is based on the principle of magnetic balance. The magnetic field generated by the current flowing through the primary coil is compensated by the magnetic field generated by the secondary coil, so that the Hall device is always in a working state of detecting zero magnetic flux. The speed of this process is affected by the number of coil turns. The fewer the number of turns of the winding, the smaller the inductance, the smaller the current required to generate the offset magnetic field, and the faster the response speed of the sensor.

[0021] 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 inductive impedance and a second amplifier. The ratio of the feedback output inductive impedance to the input inductive impedance of the voltage sensor is a constant, which improves the detection accuracy. One end of the feedback output inductive impedance is connected to the compensation current, and the other end is grounded 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 inductive impedance, and the detection voltage is adjusted by adjusting the amplification factor of the second amplifier so that it satisfies the set linear relationship with the voltage to be measured before the voltage is stepped down.

[0022] Specific as Figure 1 As shown, the voltage detection device in the embodiment is composed of an iron core 1, a primary coil 2, a current limiting resistor 12, a Hall voltage 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 inductive impedance 10. The input inductive impedance of the primary coil 2 is Z a, the current limiting resistor value is R3. Under the premise that the Hall sensor works normally, increase the resistance value of the current limiting resistor 12 R3 and the input inductive impedance Z of the primary coil 2 a The ratio of the electromagnetic time constant is reduced, so the response speed of the sensor is significantly improved. At the same time, the original primary coil of the Hall sensor is utilized, and there is no need to add more circuit components, which helps to simplify the circuit design.

[0023] like Figure 2 As shown, a voltage follower 3 is connected in series before the current limiting resistor 12. At the sensor detection end, the voltage to be measured is first divided by resistance, and the small signal obtained by the voltage division is used as the input signal of the voltage follower. The output of the voltage follower passes through the current limiting resistor and is connected to the primary coil of the closed-loop Hall sensor. The voltage follower 3 can increase the current flowing through the current limiting resistor 12 and the primary coil. At this time, the resistance value R3 of the current limiting resistor 12 and the input inductive impedance Z of the primary coil 2 can be increased to the maximum extent. a ratio, further reducing the electromagnetic time constant and improving the response speed of the sensor.

[0024] like Figure 1 As shown, the primary coil 2 and the feedback coil 8 are wound on the ring core 1, and the voltage U1 to be measured is connected in series with Z a After voltage division with R3 voltage divider circuit, the small voltage obtained is applied to primary coil 2. Hall element 5 is installed at the air gap of core 1 to detect the magnetic flux Φ1 generated by primary coil 2 on 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 voltage U2 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 tends to zero, thereby realizing automatic correction of the Hall element 5.

[0025] The voltage U that actually passes through the primary coil is a It is much smaller than the measured voltage U1. Therefore, in order to offset the magnetic flux generated by U1 on the iron core, the feedback voltage U2 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 voltage U2 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 voltage U aThe reduction reduces the air gap working magnetic flux density range and indirectly improves the response speed of the Hall sensor itself.

[0026] In addition, by measuring the output voltage U' on the feedback output inductive impedance 10 Z The feedback voltage U2 can be obtained, so in order to be able to measure the output voltage U' z The magnitude of the initial voltage U to be measured before voltage division is obtained, and the two ends of the feedback output inductive impedance 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 U Z It satisfies the set linear relationship with the measured voltage U1, thereby improving the detection accuracy.

[0027] 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 r m is the excitation resistance, l m is the excitation inductance, r3 is the current limiting resistor, 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 Z' is the equivalent impedance of the feedback output impedance from the secondary circuit to the primary circuit.

[0028] According to the circuit equivalent model, the input impedance of the Hall voltage sensor is:

[0029]

[0030] The ratio of the detection voltage to the initial voltage to be measured is,

[0031]

[0032] Where KH is the Hall potential and the excitation current i m The ratio of 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 set excitation impedance r m +jωl m and output loop impedance (KH·PID)'+r m +jωl m +Z'+r'2+jωl'2 ratio.

[0033]

[0034] Formula (2) can be transformed into

[0035]

[0036] By adjusting parameters such as (KH·PID)' and equivalent impedance Z', the real part and the imaginary part in formula (3) can be made to satisfy a certain proportional relationship, thereby calculating the constant C1. Substituting the known constant C1, equivalent impedance Z', equivalent resistance r'2, and equivalent leakage inductance l'2 into formula (4), by adjusting the primary coil resistance r1, the leakage inductance l1 of the primary coil, and the current limiting resistor r3, the real part and the imaginary part in the formula can be made to satisfy a certain proportional relationship, thereby calculating the ratio of the detection voltage to the initial voltage to be measured as the constant C2.

[0037] This method not only ensures that the ratio of the feedback output inductive impedance 10 to the input inductive impedance of the voltage sensor is a constant, thus ensuring the detection accuracy of the sensor when detecting high-frequency voltage, but also eliminates the influence of the excitation impedance on the detection accuracy.

Claims

1. A method for implementing a high-performance voltage detection device, characterized in that: Its structure includes a Hall voltage 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, the 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 primary coil due to the voltage to be measured, and output the generated compensation voltage through the other end of the feedback coil, and the compensation voltage excites the feedback coil to generate a reverse magnetic flux to offset the magnetic flux generated by the voltage to be measured; the primary coil is connected to a voltage divider module, and the voltage divider module and the input inductive impedance of the primary coil form a voltage divider circuit, which is used to reduce the voltage to be measured applied to both ends of the primary coil.

2. The method according to claim 1, characterized in that The voltage divider module includes a current limiting resistor, a first end of the current limiting resistor is connected to one end of the primary coil, and two ends of the initial voltage to be measured are respectively connected to the second end of the current limiting resistor and the other end of the primary coil, and the voltage to be measured is generated after voltage division.

3. The method according to claim 2, characterized in that The voltage divider module also includes a first voltage divider resistor, a second voltage divider resistor and a voltage follower. The second end of the first voltage divider resistor is respectively connected to the first end of the second voltage divider resistor and the input end of the voltage follower, the output end of the voltage follower is connected to the second end of the current limiting resistor, and the two ends of the initial voltage to be measured are respectively connected to the first end of the first voltage divider resistor and the second end of the second voltage divider resistor.

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 inductive impedance, one end of which is connected to the compensation voltage and the other end is grounded, so as to convert the compensation voltage into a detection voltage.

8. The method according to claim 7, characterized in that The readout module further includes a second amplifier connected in parallel to both ends of the feedback output inductive impedance, and the second amplifier is used to adjust the detection voltage so that the adjusted detection voltage satisfies a set linear relationship with the initial voltage to be measured.

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 inductive impedance.

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