CN114428220B - High-precision serial measurement method for asymmetry factor of differential transformer - Google Patents
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Abstract
The invention discloses a high-precision serial measurement method of an asymmetric factor of a differential transformer, wherein the differential transformer comprises two primary coils L1 and L2 and a secondary coil L3, and the high-precision serial measurement method comprises the following steps: connecting two primary coils L1, L2 in series; after the AC carrier source is connected with an external resistor R1, an AC carrier signal V P is input into the two primary coils L1 and L2 which are connected in series; amplifying the voltage signal V L3 which is induced by the secondary coil L3 and contains the asymmetry factor of the primary coil to obtain a voltage signal V sout which contains the asymmetry factor; sequentially carrying out alternating current amplification, demodulation and filtering on the voltage signal V sout to obtain a direct current voltage signal V d; and obtaining and according to the amplification, alternating current amplification, demodulation and filtering parameters, obtaining a transfer function of the asymmetry factor and the direct current voltage signal V d, and calculating according to the direct current voltage signal V d to obtain the primary coil asymmetry factor. The invention can realize the measurement of the primary coil asymmetry factor in the differential transformer.
Description
Technical Field
The invention belongs to the technical field of capacitance displacement sensing measurement, and particularly relates to a high-precision serial measurement method for an asymmetry factor of a differential transformer.
Background
The high-precision capacitive displacement sensor is used as a traditional non-contact sensor and is mainly applied to an inertial measurement device for measuring capacitance change, such as an accelerometer and the like. The high-precision capacitive displacement sensor mainly comprises a capacitive bridge, a front-end circuit, a modem and a low-pass filter circuit and the like. High-precision capacitive displacement sensors based on transformer bridges are widely applied to space electrostatic accelerometers and inertial sensors. In the space inertial sensor, a capacitance displacement sensing circuit measures the variation of the position of the inspection mass in the probe, and the inspection mass in the probe is controlled to be in a zero position through a feedback circuit.
The transformer bridge converts the capacitance signal into a voltage signal, and the voltage signal is transmitted to the post-stage circuit through the amplifying circuit, and the two differential primary coils of the transformer bridge are perfectly symmetrical under ideal conditions, but cannot be realized in reality, so that the asymmetry of the primary coils can generate false displacement signals. Meanwhile, for transformer design and manufacture, the primary coil is asymmetric due to factors such as coil winding mode, magnetic core non-uniformity, glue filling process and the like.
Therefore, the asymmetry of the differential transformer needs to be measured to measure the magnitude of the sensing offset due to the asymmetry of the primary winding, which provides a reference for the transformer design and manufacturing process.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a high-precision serial measurement method for the asymmetry factor of a differential transformer, which can measure the asymmetry factor of a primary coil in the differential transformer.
To achieve the above object, in a first aspect, the present invention provides a high-precision series measurement method of an asymmetry factor of a differential transformer including two primary coils L1, L2 and a secondary coil L3, the method comprising the steps of:
(1) Connecting two of the primary coils L1, L2 in series;
(2) After the AC carrier source is connected with an external resistor R1, an AC carrier signal V P is input into the two primary coils L1 and L2 which are connected in series;
(3) Amplifying the voltage signal V L3 which is induced by the secondary coil L3 and contains the asymmetry factor of the primary coil to obtain a voltage signal V sout which contains the asymmetry factor;
(4) Sequentially performing alternating current amplification, demodulation and filtering on the voltage signal V sout to obtain a direct current voltage signal V d;
(5) And (3) obtaining and obtaining a transfer function of the asymmetry factor and the direct current voltage signal V d according to the amplification, alternating current amplification, demodulation and filtering parameters, and calculating to obtain the primary coil asymmetry factor according to the direct current voltage signal V d obtained in the step (4).
The high-precision serial measurement method of the differential transformer asymmetry factor provided by the invention is characterized in that the primary coil asymmetry factor in the differential transformer is converted into the secondary coil output through high-frequency modulation, and is converted into a stable direct-current voltage signal V d after being amplified, demodulated, filtered and the like, and the magnitude of the differential transformer asymmetry factor can be calculated according to the transfer function of the asymmetry factor and the direct-current voltage signal V d, so that the measurement of the differential transformer asymmetry factor is realized. And the parameters of amplification and alternating current amplification can be designed, so that the gain is improved, the small signal of the asymmetry factor of the differential transformer is converted and amplified, and the measurement resolution of the asymmetry factor is improved, thereby realizing high-precision measurement.
In one embodiment, the method further comprises:
(6) And adjusting the frequency of the alternating current carrier wave source, and obtaining the change condition of the asymmetry factor along with the frequency according to the direct current voltage signal V d of the alternating current carrier wave signal at different frequencies.
In one embodiment, the ac carrier signal V P is an ac voltage signal from 10kHz to 200 kHz.
In one embodiment, in step (3), the voltage signal V L3 is amplified by a charge amplifying circuit, wherein,
The charge amplification circuit comprises a charge amplifier U1, feedback impedance and a blocking capacitor C1, wherein the inverting input end of the charge amplifier U1 is connected with one end of the secondary coil L3 through the blocking capacitor C1, the non-inverting input end of the charge amplifier U1 and the other end of the secondary coil L3 are grounded, and the output end of the charge amplifier U1 is connected with the inverting input end of the charge amplifier U1 through the feedback impedance.
In one embodiment, the feedback impedance includes a feedback resistor and a feedback capacitor, and the feedback resistor and the feedback capacitor are connected in parallel.
In one embodiment, in step (4), the voltage signal V sout is ac-amplified by an ac amplifying circuit, wherein,
The alternating current amplifying circuit comprises a capacitor C2, a resistor R3 and an operational amplifier U2, wherein the inverting input end of the operational amplifier U2 is respectively connected with one end of the resistor R2 and one end of the resistor R3, the other end of the resistor R2 is connected with the output end of the charge amplifier U1 through the capacitor C2, the other end of the resistor R3 is connected with the output end of the operational amplifier U2, and the non-inverting input end of the operational amplifier U2 is grounded.
In one embodiment, in step (4), the ac amplified voltage signal V sout is demodulated by a demodulation circuit, where the demodulation circuit uses an analog switch, and an input end of the analog switch is connected to an output end of the operational amplifier U2.
In one embodiment, in step (4), the ac amplified, demodulated voltage signal V sout is filtered by a low pass filter circuit, wherein,
The low-pass filter circuit comprises an operational amplifier U3, capacitors C3-C4 and resistors R4-R7, wherein the inverting input end of the operational amplifier U3 is respectively connected with one end of a resistor R4, one end of a resistor R5 and one end of a capacitor C3, and the other end of the resistor R4 is connected with one output end of the analog switch; the non-inverting input end of the operational amplifier U3 is respectively connected with one end of a resistor R6, one end of a resistor R7 and one end of a capacitor C4, one end of the resistor R6 is connected with the other output end of the analog switch, and the other end of the resistor R7 and the other end of the capacitor C4 are grounded; the output end of the operational amplifier U3 is respectively connected with the other end of the resistor R5 and the other end of the capacitor C3.
In a second aspect, the invention provides a capacitive displacement sensing measurement method, which comprises the high-precision serial measurement method.
According to the capacitance displacement sensing measurement method provided by the invention, the asymmetry of two primary coils in a differential transformer in an actual high-precision capacitance displacement sensor is considered, the primary coil asymmetry factor is converted into the secondary coil output voltage through a serial connection mode of the primary coils and alternating current carrier signals V P with different frequencies, the change condition of the asymmetry factor along with the frequency can be obtained through measuring direct current voltage signals V d of alternating current carrier signals V P with different frequencies, the sensing offset caused by the asymmetry of the primary coils can be measured according to the change condition, and the accurate measurement of the displacement of different inertial measurement devices is realized.
Drawings
FIG. 1 is a flow chart of a method for providing high-precision series measurement of differential transformer asymmetry factor according to an embodiment;
FIG. 2 is a schematic circuit diagram of a charge amplifying circuit according to an embodiment;
FIG. 3 is a schematic circuit diagram of an AC amplifying circuit according to an embodiment;
FIG. 4 is a transfer function diagram of the AC amplifying circuit provided in FIG. 3;
FIG. 5 is a schematic circuit diagram of a low pass filter circuit provided by an embodiment;
fig. 6 is a transfer function diagram of the low pass filter circuit provided in fig. 5.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Aiming at the problem that the asymmetry of two primary coils in a traditional capacitance displacement detection circuit causes false displacement signals, the invention provides a high-precision serial measurement method for the asymmetry factor of a differential transformer, which is shown in fig. 1, and comprises the following steps S10-S50, wherein the steps are as follows:
s10, two primary coils L1, L2 in the differential transformer are connected in series.
S20, after the external resistor R1 is connected by utilizing the alternating current carrier source, an alternating current carrier signal V P is input into the two primary coils L1 and L2 which are connected in series.
Specifically, the connection relation between the alternating current carrier wave source and the differential transformer comprises a connection mode a and a connection mode b, wherein the connection mode a is as follows: the alternating current carrier source is connected with the homonymous end of one primary coil L1 through an external resistor R1, the homonymous end of the primary coil L1 is connected with the homonymous end of the other primary coil L2, and the homonymous end of the primary coil L2 is grounded. The connection mode b is as follows: the alternating current carrier source is connected with the synonym end of one primary coil L1 through an external resistor R1, the synonym end of the primary coil L1 is connected with the synonym end of the other primary coil L2, and the synonym end of the primary coil L2 is grounded. The connection mode can be selected according to practical situations, and the embodiment is not limited.
In this embodiment, when the two primary coils L1 and L2 are asymmetric, the ac carrier signal V P is divided by the external resistor R1 and the primary coil, and after the mutual inductance between the primary coils L1 and L2 and the secondary coil L3, a voltage signal V L3 containing the primary coil asymmetry factor is induced in the secondary coil L3, which is obtained according to the principle of voltage division and mutual inductance voltage calculation:
Wherein L 0 represents the common mode value of the inductance of the primary coil L1 and L2; (α 1-α2) represents an asymmetry factor of the primary coils L1 and L2 in the differential transformer, wherein α 1 represents a difference factor of the differential transformer primary coil L1 with respect to the common mode value L 0, and α 2 represents a difference factor of the differential transformer primary coil L2 with respect to the common mode value L 0; v P is an expression for frequency, S represents the expression of the angular frequency in the complex frequency domain, which can be written as s=jω; l 3 denotes an inductance value of the secondary coil L3; r 1 represents the resistance of the external resistor R1.
It should be noted that α 1、α2 is a comprehensive difference factor caused by the asymmetry of the coupling factor K and the inductance value L of the two primary coils L1 and L2 of the differential transformer to the secondary coil L3, and is introduced through the mutual inductance relationship between the primary coil and the secondary coil of the transformer, and the specific relational expression is derived as follows:
Wherein M 1 represents the mutual inductance factor of the primary coil L1 and the secondary coil L3, and M 2 represents the mutual inductance factor of the primary coil L2 and the secondary coil L3; k 1 represents a coupling factor of the primary coil L1 and the secondary coil L3, and K 2 represents a coupling factor of the primary coil L2 and the secondary coil L3; η L denotes the inductance asymmetry factor, Where L 1 represents the inductance value of the primary coil L1, and L 2 represents the inductance value of the primary coil L2.
As can be seen from the above expression, the voltage signal V L3 is an ac voltage signal of the same frequency as the ac carrier signal V P, and the ac carrier signal V P is a function related to the frequency f, and the voltage signal V L3 is a function related to the asymmetry factor (α 1-α2) and the frequency f.
S30, amplifying the voltage signal V L3 which is induced by the secondary coil L3 and contains the asymmetry factor of the primary coil, specifically, amplifying the charge or amplifying the instrument to obtain a voltage signal V sout which contains the asymmetry factor.
In step S30, since the voltage signal V L3 induced by the secondary coil is in the microvolt level, in order to facilitate the subsequent observation of the voltage signal V L3, the obtained voltage signal V L3 needs to be amplified to obtain the voltage signal V sout containing the asymmetry factor.
And S40, sequentially carrying out alternating current amplification, demodulation and filtering on the voltage signal V sout to obtain a direct current voltage signal V d.
S50, obtaining and according to amplification, alternating current amplification, demodulation and filtering parameters, obtaining a transfer function of the asymmetry factor and the direct current voltage signal V d, and calculating according to the direct current voltage signal V d obtained in the step S40 to obtain the primary coil asymmetry factor.
In steps S40 and S50, in order to obtain a more visual and stable measurement result, the voltage signal V sout obtained by the amplification process may be amplified again, then demodulated into the dc voltage signal V d, and then filtered to obtain the low-frequency dc voltage signal V d containing the asymmetry factor of the differential transformer. And then, according to the amplification, alternating current amplification, demodulation and filtering parameters, a transfer function of the asymmetry factor and the direct current voltage signal V d can be obtained, and finally, the primary coil asymmetry factor (alpha 1-α2) can be calculated by measuring the relation between the direct current voltage signal V d and the transfer function.
In order to further improve the measurement resolution of the asymmetry factor and realize high-precision measurement, the amplification, alternating current amplification, demodulation and filtering parameters can be correspondingly adjusted to improve the gain, so that the small signal of the asymmetry factor of the differential transformer is converted and amplified, and high-precision measurement is realized.
According to the high-precision serial measurement method for the asymmetric factor of the differential transformer, the primary coil asymmetric factor in the differential transformer is converted into the secondary coil output through high-frequency modulation, and is converted into a stable direct-current voltage signal V d after being amplified, amplified by alternating current, demodulated, filtered and the like, and the magnitude of the asymmetric factor of the differential transformer can be calculated according to the transfer function of the asymmetric factor and the direct-current voltage signal V d, so that the measurement of the asymmetric factor of the differential transformer is realized. And the parameters of amplification and alternating current amplification can be designed, so that the gain is improved, the small signal of the asymmetry factor of the differential transformer is converted and amplified, and the measurement resolution of the asymmetry factor is improved, thereby realizing high-precision measurement.
In one embodiment, in view of the fact that the inductance value of the coil is related to frequency, in order to more accurately measure the asymmetry factor of the transformer, the improved high-precision series measurement method of the present invention may further include step S60, which is described in detail below:
S60, adjusting the frequency of an alternating current carrier wave source, and obtaining the change condition of an asymmetry factor along with the frequency according to the direct current voltage signal V d of the alternating current carrier wave signal at different frequencies.
In step S60, the magnitude of the dc voltage signal V d at different frequencies can be measured by adjusting the frequency of the ac carrier signal V P, so as to measure the variation of the asymmetry factor of the differential transformer along with the frequency, thereby facilitating the subsequent use of the differential transformer to provide reliable reference for capacitance displacement measurement of different inertial measurement devices.
It should be noted that, the differential transformer is generally applied in a range from 1kHz to 1MHz, and when the self-resonant frequency is higher, the coil externally exhibits a capacitance characteristic, and cannot operate normally. In general, the mH differential transformer is characterized in that the coil exhibits a stable inductance state in the range of 10kHz to 200kHz, and after the frequency is higher than 200kHz, the inductance in a single coil resonates with the distributed capacitance to fail to operate normally, so that the frequency of the ac carrier signal V P provided by this embodiment can be set to 10kHz to 200kHz.
In one embodiment, in step S30, the voltage signal V L3 may be subjected to charge or instrumentation amplification by using a charge amplification circuit or an instrumentation amplification circuit, and in this embodiment, the charge amplification circuit is used to perform charge amplification on the voltage signal V L3, as shown in fig. 2, where the charge amplification circuit includes a charge amplifier U1, a feedback impedance, and a blocking capacitor C1.
Specifically, taking the connection mode a of the ac carrier wave source and the differential transformer provided in the above embodiment as an example, the connection relationship between the amplifying circuit and the differential transformer provided in this embodiment is as follows: the inverting input end of the charge amplifier U1 is connected with the homonymous end of the secondary coil L3 through a blocking capacitor C1, the non-inverting input end of the charge amplifier U1 and the heteronymous end of the secondary coil L3 are grounded, and the output end of the charge amplifier U1 is connected with the inverting input end thereof through feedback impedance. Similarly, when the ac carrier source and the differential transformer are in the connection b, the connection relationship between the amplifying circuit and the differential transformer provided in this embodiment is not described herein.
Since the voltage signal V L3 induced by the secondary coil L3 is in the order of microvolts, the subsequent voltage signal V sout containing an asymmetry factor is obtained by amplifying the subsequent voltage signal V L3 which can be connected with the blocking capacitor C1 and then connected with the charge amplifier U1,Where Z f represents the impedance value of the feedback impedance. Specifically, taking the feedback impedance as a feedback resistor (with a resistance value of R 2) and a feedback capacitor (with a capacitance value of C 2) connected in parallel as an example, the impedance of the feedback impedance can be expressed as
Further, in order to obtain a more visual and stable measurement result, the output end of the charge amplifier U1 may be further connected to a first-stage ac amplifying circuit for further amplification, the voltage signal V sout after ac amplification is demodulated into a dc voltage signal by a demodulating circuit, and then the dc voltage signal V d with a low frequency and a differential transformer asymmetry factor is obtained after the high frequency signal is filtered by a low-pass filtering circuit. Then, according to the circuit parameters, the transfer function of the asymmetry factor and the DC voltage signal V d can be obtained, so that the asymmetry factor of the primary coil can be calculated by measuring the DC voltage signal V d.
In one embodiment, referring to fig. 3, the ac amplifying circuit includes a capacitor C2, a resistor R3, and an operational amplifier U2, where an inverting input terminal of the operational amplifier U2 is connected to one end of the resistor R2 and one end of the resistor R3, respectively, and the other end of the resistor R2 is connected to an output terminal of the amplifying circuit (charge amplifier U1) through the capacitor C2, and the other end of the resistor R3 is connected to an output terminal of the operational amplifier U2, and a non-inverting input terminal of the operational amplifier U2 is grounded.
In this embodiment, the capacitor C2 is used to isolate the dc signal; the resistors R2 and R3 determine the amplification factor of the ac amplifying circuit, and in order to meet the requirement that the frequency of the ac carrier signal V P is 10kHz to 200kHz, the ac amplifying circuit is a high-pass amplifying circuit, and further amplifies the output signal V sout to V out2. Taking the example that the resistance values of the resistor R2 and the resistor R3 in the alternating current amplifying circuit provided by the embodiment are R 3 and the capacitance values of the capacitor C3-C4 are C 3, the transfer function of the circuit is thatAs shown in fig. 4.
In one embodiment, the demodulation circuit multiplies the output signal V out2 of the ac amplifying circuit with a square wave signal with the same frequency and the same phase to obtain a double frequency signal with a center frequency band of 0 and positive and negative symmetry, and the circuit design can use an analog switch to realize extraction of half-period signals, wherein an input end of the analog switch is connected with an output end of the operational amplifier U2.
In one embodiment, referring to fig. 5, the low-pass filter circuit includes an operational amplifier U3, capacitors C3 to C4, and resistors R4 to R7, where an inverting input terminal of the operational amplifier U3 is connected to one end of the resistor R4, one end of the resistor R5, one end of the capacitor C3, and the other end of the resistor R4 is connected to an output terminal of the analog switch; the non-inverting input end of the operational amplifier U3 is respectively connected with one end of a resistor R6, one end of a resistor R7 and one end of a capacitor C4, one end of the resistor R6 is connected with the other output end of the analog switch, and the other end of the resistor R7 and the other end of the capacitor C4 are grounded; the output end of the operational amplifier U3 is respectively connected with the other end of the resistor R5 and the other end of the capacitor C3.
In this embodiment, the output signal V out2 of the ac amplifying circuit is passed through a demodulation circuit and a low-pass filter circuit to obtain a low-frequency signal, and the magnitude of the asymmetry factor of the differential transformer is obtained by dividing the acquired dc voltage signal V d output by the low-pass filter circuit by a transfer function of the circuit design with respect to the asymmetry factor. Taking the low-pass filter circuit provided in this embodiment, the resistances of the resistors R4 to R7 are R 4, and the capacitances of the capacitors C3 to C4 are C 4, the transfer function of the circuit isAs shown in fig. 6.
According to the high-precision serial measurement method for the asymmetric factor of the differential transformer, the asymmetric factor of the primary coil of the differential transformer is converted into the output of the secondary coil through high-frequency modulation, amplified by the front-end amplifying circuit and the alternating current amplifying circuit, converted into a stable direct current signal by the demodulation circuit and the low-pass filtering circuit, and divided by the transfer function of the circuit design, so that the magnitude of the asymmetric factor of the differential transformer can be calculated. And the parameters of the front-end amplifying circuit and the alternating current amplifying circuit can be designed, so that the gain is improved, the small signal of the asymmetry factor of the differential transformer is converted and amplified, and the measurement resolution of the asymmetry factor is improved, thereby realizing high-precision measurement.
The invention also provides a capacitance displacement sensing measurement method, which comprises the high-precision serial measurement method of the asymmetry factor of the differential transformer.
According to the capacitance displacement sensing measurement method provided by the embodiment, in consideration of the asymmetry of two primary coils in a differential transformer in an actual high-precision capacitance displacement sensor, the primary coil asymmetry factor is converted into the secondary coil output voltage through a serial connection mode of the primary coils and alternating current carrier signals V P with different frequencies, the change condition of the asymmetry factor along with the frequency can be obtained through measuring direct current voltage signals V d of alternating current carrier signals V P with different frequencies, the sensing offset caused by the asymmetry of the primary coils can be measured according to the change condition, and the accurate measurement of displacement of different inertial measurement devices is realized.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (9)
1. A high-precision series measurement method of an asymmetry factor of a differential transformer comprising two primary coils L1, L2 and a secondary coil L3, characterized in that the method comprises the steps of:
(1) Connecting two of the primary coils L1, L2 in series;
(2) After the AC carrier source is connected with an external resistor R1, an AC carrier signal V P is input into the two primary coils L1 and L2 which are connected in series;
(3) Amplifying the voltage signal V L3 which is induced by the secondary coil L3 and contains the asymmetry factor of the primary coil to obtain a voltage signal V sout which contains the asymmetry factor;
(4) Sequentially performing alternating current amplification, demodulation and filtering on the voltage signal V sout to obtain a direct current voltage signal V d;
(5) And (3) obtaining and obtaining a transfer function of the asymmetry factor and the direct current voltage signal V d according to the amplification, alternating current amplification, demodulation and filtering parameters, and calculating to obtain the primary coil asymmetry factor according to the direct current voltage signal V d obtained in the step (4).
2. The high precision serial measurement method according to claim 1, wherein the method further comprises:
(6) And adjusting the frequency of the alternating current carrier wave source, and obtaining the change condition of the asymmetry factor along with the frequency according to the direct current voltage signal V d of the alternating current carrier wave signal at different frequencies.
3. The high-precision serial measurement method according to claim 2, wherein the ac carrier signal V P is an ac voltage signal from 10kHz to 200 kHz.
4. The high-precision serial measurement method according to claim 1, wherein in step (3), the voltage signal V L3 is amplified by a charge amplifying circuit, wherein,
The charge amplification circuit comprises a charge amplifier U1, feedback impedance and a blocking capacitor C1, wherein the inverting input end of the charge amplifier U1 is connected with one end of the secondary coil L3 through the blocking capacitor C1, the non-inverting input end of the charge amplifier U1 and the other end of the secondary coil L3 are grounded, and the output end of the charge amplifier U1 is connected with the inverting input end of the charge amplifier U1 through the feedback impedance.
5. The high-precision serial measurement method according to claim 4, wherein the feedback impedance comprises a feedback resistor and a feedback capacitor, and the feedback resistor and the feedback capacitor are connected in parallel.
6. The method of high-precision serial measurement according to claim 4, wherein in step (4), the voltage signal V sout is AC-amplified by an AC amplifying circuit, wherein,
The alternating current amplifying circuit comprises a capacitor C2, a resistor R3 and an operational amplifier U2, wherein the inverting input end of the operational amplifier U2 is respectively connected with one end of the resistor R2 and one end of the resistor R3, the other end of the resistor R2 is connected with the output end of the charge amplifier U1 through the capacitor C2, the other end of the resistor R3 is connected with the output end of the operational amplifier U2, and the non-inverting input end of the operational amplifier U2 is grounded.
7. The method according to claim 6, wherein in the step (4), the ac amplified voltage signal V sout is demodulated by a demodulation circuit, the demodulation circuit employs an analog switch, and an input terminal of the analog switch is connected to an output terminal of the operational amplifier U2.
8. The method of high-precision serial measurement according to claim 7, wherein in step (4), the AC amplified and demodulated voltage signal V sout is filtered by a low-pass filter circuit, wherein,
The low-pass filter circuit comprises an operational amplifier U3, capacitors C3-C4 and resistors R4-R7, wherein the inverting input end of the operational amplifier U3 is respectively connected with one end of a resistor R4, one end of a resistor R5 and one end of a capacitor C3, and the other end of the resistor R4 is connected with one output end of the analog switch; the non-inverting input end of the operational amplifier U3 is respectively connected with one end of a resistor R6, one end of a resistor R7 and one end of a capacitor C4, one end of the resistor R6 is connected with the other output end of the analog switch, and the other end of the resistor R7 and the other end of the capacitor C4 are grounded; the output end of the operational amplifier U3 is respectively connected with the other end of the resistor R5 and the other end of the capacitor C3.
9. A capacitive displacement sensing measurement method comprising the high-precision serial measurement method according to any one of claims 1 to 8.
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| CN202210105541.5A CN114428220B (en) | 2022-01-28 | High-precision serial measurement method for asymmetry factor of differential transformer |
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| CN202210105541.5A CN114428220B (en) | 2022-01-28 | High-precision serial measurement method for asymmetry factor of differential transformer |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101178970A (en) * | 2006-11-09 | 2008-05-14 | 联华电子股份有限公司 | High coupling factor transformer and manufacturing method therefor |
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101178970A (en) * | 2006-11-09 | 2008-05-14 | 联华电子股份有限公司 | High coupling factor transformer and manufacturing method therefor |
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