A resonant bridge performance adjustment system and method

Abstract

The present application relates to the technical field of electronic circuit, especially to a resonant bridge performance adjustment system and method, tuning capacitor is connected to the secondary winding end of transformer, the capacitance value of tuning capacitor connected to the secondary winding, when transferred to the primary winding, equivalent to the secondary tuning capacitor capacitance value change 1 unit, the primary tuning capacitor changes about 1 / 4 unit, the tuning accuracy is improved about 4 times. Resonant frequency is determined by the product of inductance value and capacitance value, using secondary winding tuning method, theoretically, the tuning capacitor can be reduced to 1 / 4 of the original scheme, the corresponding inductance capacity can be improved by about four times, the resonant bridge performance can be improved, and the maximum value of inductance value in the resonant circuit is also improved, which can further improve the capacitance sensing resolution.

Description

Technical Field

[0001] This invention belongs to the field of electronic circuit technology, and in particular relates to a resonant bridge performance adjustment system and method. Background Technology

[0002] The differential variable-gap capacitive displacement sensor is a non-contact sensor with high sensitivity and high resolution, and has been applied in gravitational wave detection projects. The resonant bridge operates at its resonant frequency, minimizing sensing circuit noise. In gravitational wave detection, a capacitive sensing resolution of 1 aF / Hz is required. 1 / 2 @1mHz.

[0003] High sensing resolution requires high resonant frequency adjustment accuracy and high resonant bridge performance. Currently, methods to improve resonant bridge performance include increasing transformer parameters (inductance value L and quality factor Q); methods to improve resonant frequency accuracy include adjusting the tuning capacitor to make the circuit operate at the desired resonant frequency. To ensure resonant bridge performance, it is necessary to increase either the transformer inductance value L or the quality factor Q. The quality factor Q is affected by the magnetic core performance. Increasing the transformer inductance value L can be achieved by increasing the number of coil turns, which is currently the main method for improving transformer performance. However, due to the resonance principle, the increase in inductance value L is limited by the total amount of tuning capacitors. Adjusting the resonant frequency can make the circuit operate at the desired resonant frequency, but the adjustment accuracy is affected by the capacitor value and capacitor precision. The smaller the capacitor value and the higher the precision, the higher the resonant frequency adjustment accuracy.

[0004] Therefore, it is necessary to propose a method to improve the inductance and resonant frequency adjustment accuracy of the resonant bridge, so as to ensure the high resonant frequency adjustment accuracy and high resonant bridge performance requirements of the bridge. Summary of the Invention

[0005] In view of this, the present invention aims to provide a resonant bridge performance adjustment system and method, which increases the maximum value of the inductance in the resonant circuit and can further improve the capacitance sensing resolution.

[0006] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A resonant bridge performance adjustment system, comprising: A differential transformer has a first primary winding, a second primary winding, and a secondary winding; Fixed capacitors are connected to the first primary winding and the second primary winding, respectively; A tuning capacitor module, connected to the secondary winding, includes a first tuning capacitor and a second tuning capacitor. One end of the first tuning capacitor is connected to the same-name terminal of the secondary winding, and the other end of the first tuning capacitor is grounded. One end of the second tuning capacitor is connected to the opposite-name terminal of the secondary winding, and the other end of the second tuning capacitor is grounded. The tuning capacitor module is used to adjust the resonant frequency of the resonant bridge.

[0007] Furthermore, the equivalent turns ratio of the primary winding to the secondary winding of the differential transformer is 2:1, and the capacitance of the tuning capacitor equivalent to that of the primary winding is 1 / 4 of the actual capacitance.

[0008] Furthermore, the system is applied in the front-end circuit of a differential variable-gap capacitive displacement sensor, and the front-end circuit also includes a sensitive probe, sensing electrodes, connecting cables, and a transimpedance amplifier.

[0009] A method for adjusting the performance of a resonant bridge includes: A differential transformer is provided, the differential transformer including a first primary winding, a second primary winding and a secondary winding; A fixed capacitor is connected to the first primary winding and the second primary winding. The fixed capacitor includes the capacitor introduced by the connecting cable and stray capacitor. The tuning capacitor is connected to the secondary winding, including a first tuning capacitor and a second tuning capacitor. One end of the first tuning capacitor is connected to the same-name terminal of the secondary winding, and the other end of the first tuning capacitor is grounded. One end of the second tuning capacitor is connected to the opposite-name terminal of the secondary winding, and the other end of the second tuning capacitor is grounded. The resonant frequency of the resonant bridge is adjusted by adjusting the capacitance of the tuning capacitor.

[0010] Furthermore, the equivalent turns ratio of the primary winding to the secondary winding of the differential transformer is 2:1, and after the tuning capacitor is connected to the secondary winding, the capacitance value equivalent to the primary winding is 1 / 4 of the capacitance value of the tuning capacitor.

[0011] Compared with the prior art, the present invention can achieve the following beneficial effects: This invention provides a resonant bridge performance adjustment system and method. A tuning capacitor is connected to the secondary winding of a transformer. When the capacitance of the tuning capacitor connected to the secondary winding is transmitted to the primary winding, it is equivalent to a 1-unit change in the capacitance of the secondary tuning capacitor, and a change of approximately 1 / 4 unit in the primary tuning capacitor, thus improving the tuning accuracy by approximately four times. The resonant frequency is determined by the product of the inductance and capacitance values. Using the secondary winding tuning method, theoretically, the tuning capacitor can be reduced to 1 / 4 of the original solution, corresponding to an approximately four-fold increase in inductance. This improves the resonant bridge performance and also increases the maximum inductance value in the resonant circuit, further enhancing the capacitance sensing resolution. Attached Figure Description

[0012] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a block diagram illustrating the principle of the primary winding tuning scheme of a resonant bridge in the prior art.

[0013] Figure 2 A schematic diagram of the resonant bridge performance adjustment system described in the embodiments of the present invention; Figure 3 The equivalent schematic diagram of the secondary winding tuning scheme of the resonant bridge performance adjustment system described in the embodiment of the present invention.

[0014] Explanation of reference numerals in the attached figures: Differential transformer 1, tuning capacitor module 2, fixed capacitor 3, first primary winding 4, second primary winding 5, secondary winding 6. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0017] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] like Figure 1 As shown, in existing technical solutions, the sensor front-end circuit generally consists of a sensitive probe, sensing electrodes, connecting cables, a differential transformer, a resonant bridge, and a transimpedance amplifier. The resonant bridge operates at its resonant frequency, resulting in the lowest noise in the sensing circuit. In gravitational wave detection, a capacitance sensing resolution of 1 aF / Hz is required. 1 / 2 At 1 MHz, due to the influence of the resonance principle, the increase in inductance value L is limited by the total amount of tuning capacitors.

[0020] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] like Figure 2 As shown in the embodiment of the present invention, a resonant bridge performance adjustment system includes: The differential transformer 1 has a first primary winding 4, a second primary winding 5, and a secondary winding 6; Fixed capacitor 3 is connected to the first primary winding 4 and the second primary winding 5 respectively, and fixed capacitor C is connected to the second primary winding 5 respectively. q1 C q2 The capacitors are connected to the A end of the first primary winding 4 and the B end of the second primary winding 5 of the differential transformer, respectively. This includes the capacitance introduced by the connecting cable and stray capacitance. The fixed capacitor does not have the ability to be adjusted. Tuning capacitor module 2, connected to secondary winding 6, includes a first tuning capacitor and a second tuning capacitor. One end of the first tuning capacitor is connected to the same-name terminal of the secondary winding 6, and the other end of the first tuning capacitor is grounded. One end of the second tuning capacitor is connected to the opposite-name terminal of the secondary winding 6, and the other end of the second tuning capacitor is grounded. Tuning capacitor module 2 is used to adjust the resonant frequency of the resonant bridge. In the figure, the first tuning capacitor C... t1 One end is connected to the same-name terminal of the secondary winding, and the first tuning capacitor C t1 The other end is grounded (GND); the second tuning capacitor is C. t2 One end is connected to the opposite terminal of the secondary winding, and the second tuning capacitor C t2 The other end is grounded to GND, and all tuning capacitor modules 2 are connected to the secondary winding 6 of the differential transformer. This can be achieved by adjusting the tuning capacitor C. t1 and tuning capacitor C t2By adjusting the size of the capacitor and the resonant frequency, the adjustment accuracy can be improved by nearly four times compared to the original scheme. Meanwhile, based on the resonance principle, a 3 / 4 times tuning capacitor C can be obtained. t1 and tuning capacitor C t2 It can be used to increase the inductance value L, which can further improve the resolution of capacitive sensing.

[0022] In some embodiments, such as Figure 3 As shown, the first tuning capacitor C of the secondary winding t1 Second tuning capacitor C t2 The changes in these values, when applied to the primary winding, are equivalent to the changes in the tuning capacitance, namely C. t1 / 4 and C t2 / 4. Meanwhile, according to the resonance principle, the tuning capacitor C is 3 / 4 times... t1 and tuning capacitor C t2 It can be used to increase the inductance value L, which can further improve the resolution of capacitive sensing.

[0023] In some embodiments, the equivalent turns ratio of the primary winding to the secondary winding of the differential transformer is n:1. In this embodiment, the total equivalent primary turns are n=2. Therefore, according to the transformer impedance transformation relationship, the capacitance Cs on the secondary side is equivalent to the capacitance Ceq on the primary side as follows: Ceq=Cs / n² When n=2, Ceq=Cs / 4.

[0024] Therefore, the secondary tuning capacitor C t1 A change in capacitance ΔC is equivalent to a capacitance change of ΔC / 4 on the primary side. This means that to achieve the same resonant frequency adjustment on the primary side, the capacitance change required on the secondary side is only 1 / 4 of that required by the primary side solution. Under the condition of the same absolute precision of the tuning capacitor, the tuning precision of the secondary solution is improved by approximately four times.

[0025] In some embodiments, the equivalent turns ratio of the primary winding to the secondary winding of the differential transformer is 2:1, and the capacitance of the tuning capacitor equivalent to the primary winding is 1 / 4 of the actual capacitance.

[0026] In some embodiments, the system is applied in the front-end circuit of a differential variable-gap capacitive displacement sensor, and the front-end circuit further includes a sensitive probe, sensing electrodes, connecting cables, and a transimpedance amplifier.

[0027] This invention provides a resonant bridge performance adjustment system. A tuning capacitor is connected to the secondary winding of a transformer. When the capacitance of the tuning capacitor connected to the secondary winding is transmitted to the primary winding, it is equivalent to a 1-unit change in the secondary tuning capacitor's capacitance, while the primary tuning capacitor changes by approximately 1 / 4 unit, thus improving tuning accuracy by about four times. The resonant frequency is determined by the product of the inductance and capacitance values. Using the secondary winding tuning method, theoretically, the tuning capacitor can be reduced to 1 / 4 of the original solution, corresponding to an approximately four-fold increase in inductance. This improves the resonant bridge performance and also increases the maximum inductance value in the resonant circuit, further enhancing capacitive sensing resolution.

[0028] like Figure 3 As shown in the embodiment of the present invention, a method for adjusting the performance of a resonant bridge includes: S1. A differential transformer is provided, the differential transformer including a first primary winding, a second primary winding and a secondary winding; S2. Connect a fixed capacitor to the first primary winding and the second primary winding. The fixed capacitor includes the capacitor introduced by the connecting cable and stray capacitor. S3. Connect the tuning capacitor to the secondary winding, including a first tuning capacitor and a second tuning capacitor. One end of the first tuning capacitor is connected to the same-name terminal of the secondary winding, and the other end of the first tuning capacitor is grounded. One end of the second tuning capacitor is connected to the opposite-name terminal of the secondary winding, and the other end of the second tuning capacitor is grounded. S4. Adjust the resonant frequency of the resonant bridge by adjusting the capacitance of the tuning capacitor.

[0029] In some embodiments, the equivalent turns ratio of the primary winding to the secondary winding of the differential transformer is 2:1, and after the tuning capacitor is connected to the secondary winding, the capacitance value equivalent to the primary winding is 1 / 4 of the capacitance value of the tuning capacitor.

[0030] Fixed capacitor C q1 Fixed capacitor C q2 The capacitors connected to terminals A of the first primary winding and B of the differential transformer, respectively, include the capacitance introduced by the connecting cables and stray capacitance. First tuning capacitor C t1 One end is connected to the same-name terminal of the secondary winding, and the second tuning capacitor C t1 The other end is grounded; the second tuning capacitor C t2 One end is connected to the opposite terminal of the secondary winding, and the second tuning capacitor C t2 The other end is grounded. At this time, capacitor C... q1 Capacitor C q2 Almost all capacitors are fixed and lack adjustment capability. The entire tuning capacitor module is connected to the secondary winding of the differential transformer, and can be adjusted by adjusting the first tuning capacitor C. t1 Second tuning capacitor C t2The size of the secondary winding tuning capacitor C is adjusted to change the resonant frequency, and the adjustment accuracy can be improved by nearly 4 times compared with the original scheme. t1 and tuning capacitor C t2 The changes in these values, when applied to the primary winding, are equivalent to the changes in the tuning capacitance, namely C. t1 / 4 and C t2 / 4. Meanwhile, according to the resonance principle, the tuning capacitor C is 3 / 4 times... t1 and tuning capacitor C t2 It can be used to increase the inductance value L, which can further improve the resolution of capacitive sensing.

[0031] This invention provides a resonant bridge performance adjustment system. A tuning capacitor is connected to the secondary winding of a transformer. The capacitance value of the tuning capacitor connected to the secondary winding, when transmitted to the primary winding, is equivalent to a 1-unit change in the secondary tuning capacitor value and approximately a 1 / 4-unit change in the primary tuning capacitor value, thus improving tuning accuracy by approximately four times. The resonant frequency is determined by the product of the inductance and capacitance values. Using the secondary winding tuning method, theoretically, the tuning capacitor can be reduced to 1 / 4 of the original solution, corresponding to an approximately four-fold increase in inductance. This improves the resonant bridge performance and also increases the maximum inductance value in the resonant circuit, further enhancing capacitance sensing resolution.

[0032] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A resonant bridge performance adjustment system, characterized in that, include: A differential transformer has a first primary winding, a second primary winding, and a secondary winding; Fixed capacitors are connected to the first primary winding and the second primary winding, respectively; A tuning capacitor module, connected to the secondary winding, includes a first tuning capacitor and a second tuning capacitor. One end of the first tuning capacitor is connected to the same-name terminal of the secondary winding, and the other end of the first tuning capacitor is grounded. One end of the second tuning capacitor is connected to the opposite-name terminal of the secondary winding, and the other end of the second tuning capacitor is grounded. The tuning capacitor module is used to adjust the resonant frequency of the resonant bridge.

2. The resonant bridge performance adjustment system according to claim 1, characterized in that, The equivalent turns ratio of the primary winding to the secondary winding of the differential transformer is 2:1, and the capacitance of the tuning capacitor equivalent to that of the primary winding is 1 / 4 of the actual capacitance.

3. The resonant bridge performance adjustment system according to claim 1, characterized in that, The system is used in the front-end circuit of a differential variable-gap capacitive displacement sensor. The front-end circuit also includes a sensitive probe, sensing electrodes, connecting cables, and a transimpedance amplifier.

4. A method for adjusting the performance of a resonant bridge, characterized in that, include: A differential transformer is provided, the differential transformer including a first primary winding, a second primary winding and a secondary winding; A fixed capacitor is connected to the first primary winding and the second primary winding. The fixed capacitor includes the capacitor introduced by the connecting cable and stray capacitor. The tuning capacitor is connected to the secondary winding, including a first tuning capacitor and a second tuning capacitor. One end of the first tuning capacitor is connected to the same-name terminal of the secondary winding, and the other end of the first tuning capacitor is grounded. One end of the second tuning capacitor is connected to the opposite-name terminal of the secondary winding, and the other end of the second tuning capacitor is grounded. The resonant frequency of the resonant bridge is adjusted by adjusting the capacitance of the tuning capacitor.

5. The method for adjusting the performance of a resonant bridge according to claim 4, characterized in that, The equivalent turns ratio of the primary winding to the secondary winding of the differential transformer is 2:

1. After the tuning capacitor is connected to the secondary winding, the capacitance value of the primary winding is equivalent to 1 / 4 of the capacitance value of the tuning capacitor.

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