Rectifying circuit and displacement measurement method and displacement measurement system based on rectifying circuit

Abstract

The invention discloses a rectification circuit and a displacement measurement method and a displacement measurement system based on the rectification circuit. Wherein the rectifying circuit comprises a first operational amplifier circuit and a second operational amplifier circuit, a first input resistor in the first operational amplifier circuit is connected with an inverted input end of a first operational amplifier, a first feedback resistor is connected with the first operational amplifier in parallel, a first diode is connected with the first operational amplifier in parallel, and a second diode is connected with the first operational amplifier in series; the second operational amplifier circuit is connected with the first operational amplifier circuit in series through a second input resistor, the input end of the second input resistor in the second operational amplifier circuit is connected with the positive electrode of a second diode, the output end of the second input resistor is connected with the inverted input end of a second operational amplifier, and a third input resistor is connected with the inverted input end of the second operational amplifier. The second feedback resistor is connected in parallel with the second operational amplifier. According to the invention, the problem of test precision caused by phase difference in a displacement measurement system based on the differential transformer is successfully solved.

Description

Rectifier circuit and displacement measurement method and system based thereon Technical Field

[0001] This invention relates to the field of measurement circuit technology, and in particular to a rectifier circuit and a displacement measurement method and system based thereon. Background Technology

[0002] In engineering applications, especially in displacement sensors for aerospace and other fields, the measurement accuracy requirements for differential transformer-based sensors are extremely high. Differential transformer-based measurement circuits use analog switching rectification to process the excitation and feedback voltages. When there is a phase difference between the excitation and feedback voltages, the rectified output voltage waveform will be distorted, leading to a significant increase in acquisition error. Summary of the Invention

[0003] To address at least one technical problem in the prior art, embodiments of the present invention provide a rectifier circuit and a displacement measurement method and system based thereon. The technical solution is as follows:

[0004] In a first aspect, the present invention provides a rectifier circuit, comprising:

[0005] The first operational amplifier circuit includes: a first operational amplifier, a first input resistor, a first feedback resistor, a first diode, and a second diode. The first input resistor is connected to the inverting input terminal of the first operational amplifier. The first feedback resistor is connected in parallel with the first operational amplifier. The first diode is connected in parallel with the first operational amplifier. The anode of the first diode is connected to the output terminal of the first operational amplifier. The cathode of the first diode is connected to the inverting input terminal of the first operational amplifier. The second diode is connected in series with the first operational amplifier. The cathode of the second diode is connected to the anode of the first diode. The anode of the second diode is connected to the first feedback resistor.

[0006] The second operational amplifier circuit includes: a second operational amplifier, a second input resistor, a third input resistor, and a second feedback resistor. The second operational amplifier circuit is connected in series with the first operational amplifier circuit through the second input resistor. The input terminal of the second input resistor is connected to the positive terminal of the second diode. The output terminal of the second input resistor is connected to the inverting input terminal of the second operational amplifier. The third input resistor is connected to the inverting input terminal of the second operational amplifier. The second feedback resistor is connected in parallel with the second operational amplifier.

[0007] Furthermore, the resistance values ​​of the third input resistor and the second feedback resistor are equal, and the resistance value of the second input resistor is half the resistance value of the first input resistor.

[0008] Furthermore, the rectifier circuit also includes:

[0009] The electrical signal input terminal is connected to the input terminal of the first input resistor and the input terminal of the third input resistor;

[0010] The electrical signal output terminal is connected to the output terminal of the second operational amplifier.

[0011] The second diode is adapted to be cut off when the input electrical signal at the electrical signal input terminal is a negative half-axis electrical signal, and to be turned on when the input electrical signal at the electrical signal input terminal is a positive half-axis electrical signal, so that the electrical signal output terminal outputs a positive half-axis DC electrical signal.

[0012] Furthermore, the resistance values ​​of the first input resistor and the first feedback resistor are both equal to the resistance value of the third input resistor.

[0013] Secondly, embodiments of the present invention disclose a displacement measurement method, including:

[0014] An excitation electrical signal is sent to a differential transformer, which is connected to the target under test;

[0015] The differential transformer receives the first feedback signal and the second feedback signal generated after receiving the excitation signal;

[0016] The first feedback electrical signal and the second feedback electrical signal are rectified using the rectifier circuit described in any one of the first aspects;

[0017] The motion displacement of the target under test is calculated based on the rectified first feedback electrical signal and the second feedback electrical signal.

[0018] Further, rectifying the first feedback signal and the second feedback signal includes:

[0019] When the negative half-axis electrical signal of the first feedback signal is input into the rectifier circuit, the second diode in the rectifier circuit is cut off; when the positive half-axis electrical signal of the first feedback signal is input into the rectifier circuit, the second diode in the rectifier circuit is turned on, and the rectifier circuit outputs the positive half-axis DC electrical signal of the first feedback signal.

[0020] When the negative half-axis electrical signal of the second feedback signal is input to the rectifier circuit, the second diode in the rectifier circuit is cut off. When the positive half-axis electrical signal of the second feedback signal is input to the rectifier circuit, the second diode in the rectifier circuit is turned on, and the rectifier circuit outputs the positive half-axis DC electrical signal of the second feedback signal.

[0021] Further, the step of calculating the motion displacement of the target under test based on the rectified first feedback electrical signal and the second feedback electrical signal includes:

[0022] Calculate the sum-difference ratio of the first feedback electrical signal and the second feedback electrical signal;

[0023] The motion displacement of the target to be measured is determined based on the sum-difference ratio.

[0024] Thirdly, embodiments of the present invention disclose a displacement measurement system, comprising:

[0025] The communication module is used to send an excitation electrical signal to the differential transformer, wherein the differential transformer is connected to the target under test, and to receive a first feedback electrical signal and a second feedback electrical signal generated by the differential transformer after receiving the excitation electrical signal.

[0026] The rectifier circuit as described in any one of the first aspects is used to rectify the first feedback electrical signal and the second feedback electrical signal;

[0027] The controller is used to calculate the motion displacement of the target under test based on the rectified first feedback electrical signal and the second feedback electrical signal.

[0028] Furthermore, the displacement measurement system also includes:

[0029] A direct digital frequency synthesizer is connected to the controller;

[0030] A zero-adjustment circuit is connected to the direct digital frequency synthesizer;

[0031] An amplifier circuit, the input terminal of which is connected to the zeroing circuit, and the output terminal of which is connected to the differential transformer.

[0032] Furthermore, the displacement measurement system also includes:

[0033] The analog-to-digital signal acquisition module is connected to the rectifier circuit and the controller.

[0034] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0035] This invention successfully solves the measurement accuracy problem caused by phase difference in displacement measurement systems based on differential transformers by employing a precision rectifier circuit composed of operational amplifiers and diodes. The displacement measurement system disclosed in this invention features high precision, good versatility, and adaptability. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 is a schematic diagram of the differential sensor principle;

[0038] Figure 2 is a schematic diagram of a switching rectifier circuit;

[0039] Figure 3 is a schematic diagram of a switching rectifier circuit rectifying a signal with no phase difference;

[0040] Figure 4 is a schematic diagram of a switching rectifier circuit rectifying signals with phase difference;

[0041] Figure 5 is a schematic diagram of the rectifier circuit disclosed in an embodiment of the present invention;

[0042] Figure 6 is a flowchart of the displacement measurement method disclosed in an embodiment of the present invention;

[0043] Figure 7 is a circuit diagram of the displacement measurement system disclosed in an embodiment of the present invention;

[0044] Figure 8 is a schematic diagram of the excitation voltage output circuit disclosed in an embodiment of the present invention;

[0045] Figure 9 is a schematic diagram of the excitation voltage output circuit disclosed in the embodiment of the present invention applied to a displacement measurement system. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0047] It should be noted that the terms "first" and "second" used in the embodiments of the present invention are used to distinguish between two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the invention. Subsequent embodiments will not explain this in detail.

[0048] Differential transformers, including linear variable differential transformers (LVDTs) and rotating variable differential transformers (RVDTs), are mainly used in displacement sensors. A differential transformer primarily consists of an iron core, armature, primary coil, secondary coil A, and secondary coil B. Its working principle is based on electromagnetic induction, and its structure is shown in Figure 1. When a sinusoidal excitation voltage is applied to the primary coil and the iron core is in the middle position, the induced electromotive forces (EMFs) generated by secondary coils A and B are equal, and the output voltage is 0. When the iron core moves between the primary and secondary coils, the induced EMFs VA generated by secondary coil A and VB generated by secondary coil B are different. The difference between VA and VB depends on the magnitude of the iron core displacement. Within the measurement range, the difference between the amplitudes of the induced EMFs VA and VB in the secondary windings of the differential transformer has a linear relationship with the displacement of the iron core; that is, the displacement of the iron core can be calculated by measuring the amplitude of the secondary windings. Therefore, by setting a differential transformer on the target to be measured, when the target moves and generates displacement, the iron core in the differential transformer moves, generating a feedback voltage, which can then be used to calculate the displacement of the target.

[0049] For the excitation voltage and feedback voltage, a rectifier circuit is needed to rectify them. Generally, an analog switching rectifier circuit is used for rectification. As shown in Figure 2, the analog switching rectifier circuit includes an inverter, a comparator, a single-pole double-throw (SPD) switch, and an operational amplifier. The inverter is electrically connected to one input contact Y1 of the SPD switch, and the output contact X of the SPD switch is electrically connected to the operational amplifier. The comparator is connected to the SPD switch signal, controlling the moving end of the SPD switch to switch between the two input contacts. As shown in Figure 3, for any one of the excitation voltage Vjl, feedback voltage Va, and feedback voltage Vb, the inverter generates the corresponding inverted voltage. The zero-crossing comparator is used to detect whether the excitation voltage value is 0. When the voltage is detected to be 0, the zero-crossing comparator sends a control signal to the SPD switch, controlling the moving end of the SPD switch to switch between the two input contacts of the SPD switch. The two contacts at the input end of a single-pole double-throw switch receive the original voltage on one side and an inverted voltage generated by an inverter on the other side. When the moving end of the single-pole double-throw switch switches back and forth between the two contacts at the input end of the single-pole double-throw switch, the output of the single-pole double-throw switch is a DC voltage in the same direction.

[0050] As can be seen from the above, the analog switching rectifier circuit can output a DC voltage related to the displacement of the target under test by phase comparison when the excitation voltage or feedback voltage does not have a phase difference, thus meeting the basic measurement requirements.

[0051] However, when there is a phase difference between the excitation voltage and the feedback voltage, as shown in Figure 4, the voltage after the inverter still has a phase difference. The zero-crossing comparator controls the switching of the moving end of the single-pole double-throw switch according to the excitation voltage. As a result, when the moving end of the single-pole double-throw switch is switched, the excitation voltage or feedback voltage is not on the zero axis, which causes the waveform of the rectified input to be distorted.

[0052] As shown in Figure 5, the present invention discloses a rectifier circuit, including: a first operational amplifier circuit and a second operational amplifier circuit, wherein the first operational amplifier circuit and the second operational amplifier circuit are connected in series.

[0053] The first operational amplifier circuit includes: a first operational amplifier N1, a first input resistor R1, a first feedback resistor R3, a first diode D1, and a second diode D2. The first operational amplifier N1 has a non-inverting input terminal, an inverting input terminal, and an output terminal. The output terminal of the first input resistor R1 is connected to the inverting input terminal of the first operational amplifier N1. The first feedback resistor R3 is connected in parallel with the first operational amplifier N1. The first diode D1 is connected in parallel with the first operational amplifier N1, with its anode connected to the output terminal of the first operational amplifier N1 and its cathode connected to the inverting input terminal. The second diode D2 is connected in series with the first operational amplifier N1, with its cathode connected to the anode of the first diode D1 and its anode connected to the first feedback resistor R3.

[0054] The second operational amplifier circuit includes: a second operational amplifier N2, a second input resistor R4, a third input resistor R2, and a second feedback resistor R5. The second operational amplifier circuit is connected in series with the first operational amplifier circuit through the second input resistor R4. The input terminal of the second input resistor R4 is connected to the anode of the second diode D2, and the output terminal of the second input resistor R4 is connected to the inverting input terminal of the second operational amplifier N2. The input terminal of the third input resistor R2 is connected to the input terminal of the first input resistor R1, and the output terminal of the third input resistor R2 is connected to the inverting input terminal of the second operational amplifier N2. The second feedback resistor R5 is connected in parallel with the second operational amplifier N2.

[0055] In one embodiment, the rectifier circuit disclosed in this invention further includes: a signal input terminal and a signal output terminal. The signal input terminal is connected to the input terminals of the first input resistor R1 and the third input resistor R2. The signal output terminal is connected to the output terminal of the second operational amplifier N2. The second diode D2 is adapted to be cut off when the input electrical signal at the electrical signal input terminal is a negative half-axis electrical signal, and to be turned on when the input electrical signal at the electrical signal input terminal is a positive half-axis electrical signal, so that the electrical signal output terminal outputs a positive half-axis DC electrical signal.

[0056] In one embodiment, the resistance values ​​of the third input resistor R2 and the second feedback resistor R5 are equal, and the resistance value of the second input resistor R4 is half the resistance value of the first input resistor R1, that is: R2=R5=2R4.

[0057] Furthermore, in one embodiment, the resistance values ​​of the first input resistor R1 and the first feedback resistor R3 are equal to the resistance value of the third input resistor R2, that is: R1=R2=R3=R5=2R4.

[0058] In the above embodiments of the present invention, R2, R5 and N2 form an inverting proportional amplifier circuit, and R2, R4, R5 and N2 form an adder circuit.

[0059] When the input voltage is the negative half-axis, diode D2 is cut off, and the inverting proportional amplifier circuit composed of R2, R5 and N2 flips the negative half-axis signal into an equally proportional positive half-cycle signal for output.

[0060] When the input voltage is at the positive half-axis, diode D2 conducts, and R3, R1, D1, D2, and N1 flip the positive half-axis signal into a proportional negative half-axis electrical signal. This negative half-axis signal is superimposed on the positive half-axis signal at the input terminal through an adder circuit composed of R1, R4, R5, and N2. Since R1=R5=2R4, when the input voltage is at the positive half-cycle, the final output terminal is also a positive half-axis electrical signal that is amplified by one time.

[0061] The specific principle is as follows:

[0062] In the above rectifier circuit, the AC signal is input to the rectifier circuit through the first input resistor R1. When the negative half-axis AC signal is input, the second diode D2 is cut off, and the negative half-axis signal cannot pass through the first operational amplifier circuit, but enters the second operational amplifier circuit through the third input resistor R2. In the second operational amplifier circuit, the negative half-axis signal is inverted into the positive half-axis signal V by the second operational amplifier N2. out .

[0063] When the positive half-axis AC signal is input into the rectifier circuit, the second diode D2 conducts. One positive half-axis signal is input through the inverting input of the first operational amplifier N1 and output from its output. The first operational amplifier N1 inverts the positive half-axis signal into a negative half-axis signal. This negative half-axis signal is input from the positive terminal of the first diode D1 and output from the negative terminal. It then passes through the first feedback resistor R3 and enters the second input resistor R4. From R4, it enters the second operational amplifier circuit, where it is inverted again by the second operational amplifier N2, returning the negative half-axis signal to the positive half-axis signal V. out1 The other positive half-axis electrical signal enters the second operational amplifier circuit through the third input resistor R2, and is proportionally inverted by the second operational amplifier N2 to become the negative half-axis electrical signal V. out2Finally, the positive and negative half-axis electrical signals at the output of the second operational amplifier N2 are superimposed to form a proportionally proportional positive half-axis electrical signal V. out .

[0064] Therefore, the rectifier circuit disclosed in this embodiment of the invention can rectify and process AC signals to output positive half-axis DC signals.

[0065] The specific calculation process is as follows:

[0066] When a positive half-axis electrical signal is input, D2 conducts, the voltage at point V1 is Vin+, the voltage at point V2 is 0V, the voltage at point V3 is -Vin+, and the voltage at point V4 is 0V. Therefore, V3 to V4 and V1 to V4 form an adder circuit.

[0067]

[0068] In the formula:

[0069] Vout — Output voltage value, V;

[0070] Vout1 — Output voltage value 1V;

[0071] Vout2 — Output voltage value 2V;

[0072] Vin+——Input positive half-axis voltage, V.

[0073] When the input is a negative half-axis electrical signal, D2 is cut off, and the output voltage is:

[0074]

[0075] In the formula:

[0076] Vout — Output voltage value, V;

[0077] Vin+ — Input positive half-cycle voltage, V;

[0078] Vin-——Input negative half-cycle voltage, V.

[0079] After rectification, the output signal should be entirely the positive half-axis of the input AC signal. This method is unaffected by the phase of the feedback signal; both feedback signals A and B can be rectified using this method and then filtered.

[0080] As shown in Figure 6, based on the rectifier circuit disclosed in the above embodiments of the present invention, the present invention also discloses a displacement measurement method, including:

[0081] S1. Send an excitation signal to the differential transformer, and connect the differential transformer to the target under test;

[0082] S2, Receive the first feedback signal and the second feedback signal formed after the differential transformer receives the excitation signal;

[0083] S3. Rectify the first feedback signal and the second feedback signal using a rectifier circuit;

[0084] S4. Calculate the displacement of the target under test based on the first and second feedback electrical signals after rectification.

[0085] As shown in Figure 5, the rectifier circuit includes a first operational amplifier circuit and a second operational amplifier circuit, wherein the first operational amplifier circuit and the second operational amplifier circuit are connected in series.

[0086] The first operational amplifier circuit includes: a first operational amplifier N1, a first input resistor R1, a first feedback resistor R3, a first diode D1, and a second diode D2. The first operational amplifier N1 has a non-inverting input terminal, an inverting input terminal, and an output terminal. The output terminal of the first input resistor R1 is connected to the inverting input terminal of the first operational amplifier N1. The first feedback resistor R3 is connected in parallel with the first operational amplifier N1. The first diode D1 is connected in parallel with the first operational amplifier N1, with its anode connected to the output terminal of the first operational amplifier N1 and its cathode connected to the inverting input terminal. The second diode D2 is connected in series with the first operational amplifier N1, with its cathode connected to the anode of the first diode D1 and its anode connected to the first feedback resistor R3.

[0087] The second operational amplifier circuit includes: a second operational amplifier N2, a second input resistor R4, a third input resistor R2, and a second feedback resistor R5. The second operational amplifier circuit is connected in series with the first operational amplifier circuit through the second input resistor R4. The input terminal of the second input resistor R4 is connected to the anode of the second diode D2, and the output terminal of the second input resistor R4 is connected to the inverting input terminal of the second operational amplifier N2. The input terminal of the third input resistor R2 is connected to the input terminal of the first input resistor R1, and the output terminal of the third input resistor R2 is connected to the inverting input terminal of the second operational amplifier N2. The second feedback resistor R5 is connected in parallel with the second operational amplifier N2.

[0088] In one embodiment, step S3 includes:

[0089] When the negative half-axis electrical signal of the first feedback signal is input into the rectifier circuit, the second diode D2 in the rectifier circuit is cut off. When the positive half-axis electrical signal of the first feedback signal is input into the rectifier circuit, the second diode D2 in the rectifier circuit is turned on, and the rectifier circuit outputs the positive half-axis DC electrical signal of the first feedback signal.

[0090] When the negative half-axis electrical signal of the second feedback signal is input into the rectifier circuit, the second diode D2 in the rectifier circuit is cut off. When the positive half-axis electrical signal of the second feedback signal is input into the rectifier circuit, the second diode D2 in the rectifier circuit is turned on, and the rectifier circuit outputs the positive half-axis DC electrical signal of the second feedback signal.

[0091] In one embodiment, step S4 includes:

[0092] Calculate the sum-difference ratio of the first feedback electrical signal and the second feedback electrical signal;

[0093] The displacement of the target under test is determined by the sum-difference ratio of the first and second feedback electrical signals.

[0094] As described above, during measurement, the data acquisition system samples the feedback A and feedback B voltages, as well as the excitation voltage, and calculates the difference and ratio. The calculation formula is:

[0095] P=(U A -U B ) ÷(U A +U B )

[0096] Where P represents the difference and ratio, U A U is the voltage fed back from phase A. B This is the voltage for feedback in phase B.

[0097] As shown in Figure 7, based on the displacement measurement method disclosed in the above embodiments of the present invention, the present invention also discloses a displacement measurement system, including:

[0098] The communication module is used to send an excitation electrical signal to the differential transformer, wherein the differential transformer is connected to the target under test, and to receive a first feedback electrical signal and a second feedback electrical signal generated by the differential transformer after receiving the excitation electrical signal.

[0099] A rectifier circuit is used to rectify the first feedback electrical signal and the second feedback electrical signal;

[0100] The controller is used to calculate the motion displacement of the target under test based on the rectified first feedback electrical signal and the second feedback electrical signal.

[0101] As shown in Figure 7, two rectifier circuits can be configured to rectify the first feedback signal and the second feedback signal, respectively. Exemplarily, the controller includes a CPU and an FPGA. The differential transformer includes a linear variable differential transformer (LVDT) and a rotating variable differential transformer (RVDT).

[0102] As shown in Figure 5, the rectifier circuit includes a first operational amplifier circuit and a second operational amplifier circuit, wherein the first operational amplifier circuit and the second operational amplifier circuit are connected in series.

[0103] The first operational amplifier circuit includes: a first operational amplifier N1, a first input resistor R1, a first feedback resistor R3, a first diode D1, and a second diode D2. The first operational amplifier N1 has a non-inverting input terminal, an inverting input terminal, and an output terminal. The output terminal of the first input resistor R1 is connected to the inverting input terminal of the first operational amplifier N1. The first feedback resistor R3 is connected in parallel with the first operational amplifier N1. The first diode D1 is connected in parallel with the first operational amplifier N1, with its anode connected to the output terminal of the first operational amplifier N1 and its cathode connected to the inverting input terminal. The second diode D2 is connected in series with the first operational amplifier N1, with its cathode connected to the anode of the first diode D1 and its anode connected to the first feedback resistor R3.

[0104] The second operational amplifier circuit includes: a second operational amplifier N2, a second input resistor R4, a third input resistor R2, and a second feedback resistor R5. The second operational amplifier circuit is connected in series with the first operational amplifier circuit through the second input resistor R4. The input terminal of the second input resistor R4 is connected to the anode of the second diode D2, and the output terminal of the second input resistor R4 is connected to the inverting input terminal of the second operational amplifier N2. The input terminal of the third input resistor R2 is connected to the input terminal of the first input resistor R1, and the output terminal of the third input resistor R2 is connected to the inverting input terminal of the second operational amplifier N2. The second feedback resistor R5 is connected in parallel with the second operational amplifier N2.

[0105] In one embodiment, the rectifier circuit disclosed in this invention further includes: a signal input terminal and a signal output terminal. The signal input terminal is connected to the input terminals of the first input resistor R1 and the third input resistor R2. The signal output terminal is connected to the output terminal of the second operational amplifier N2. The second diode D2 is adapted to be cut off when the input electrical signal at the electrical signal input terminal is a negative half-axis electrical signal, and to be turned on when the input electrical signal at the electrical signal input terminal is a positive half-axis electrical signal, so that the electrical signal output terminal outputs a positive half-axis DC electrical signal.

[0106] In one embodiment, the resistance values ​​of the third input resistor R2 and the second feedback resistor R5 are equal, and the resistance value of the second input resistor R4 is half the resistance value of the first input resistor R1, that is: R2=R5=2R4.

[0107] Furthermore, in one embodiment, the resistance values ​​of the first input resistor R1 and the first feedback resistor R3 are equal to the resistance value of the third input resistor R2, that is: R1=R2=R3=R5=2R4.

[0108] In one embodiment, the controller is specifically used for:

[0109] Calculate the sum-difference ratio of the first feedback electrical signal and the second feedback electrical signal;

[0110] The motion displacement of the target under test is determined based on the sum-difference ratio of the first feedback electrical signal and the second feedback electrical signal.

[0111] In one embodiment, as shown in Figure 8, an excitation output circuit is provided between the controller and the communication module, including: a direct digital frequency synthesizer (DDS), a zero-adjustment circuit, and an amplifier circuit. The DDS is connected to the controller, and the zero-adjustment circuit is connected to the DDS; the input terminal of the amplifier circuit is connected to the zero-adjustment circuit, and the output terminal of the amplifier circuit is connected to the differential transformer.

[0112] In one embodiment, an analog-to-digital (A / D) signal acquisition module is also connected between the rectifier circuit and the controller to convert the analog signal into a digital signal that the controller can recognize.

[0113] As shown in Figure 9, a displacement measurement system including an excitation output circuit is described above. In the figure, the controller CPU sends an excitation signal, which is processed by the DDS, zero-adjustment circuit, and amplification circuit to be converted into an excitation electrical signal and transmitted to the differential transformer. The differential transformer is installed on the target being measured. When the target is displaced, the iron core in the differential transformer moves, causing the differential transformer to generate a first feedback electrical signal and a second feedback electrical signal. The first feedback electrical signal Ua, the second feedback electrical signal Ub, and the excitation feedback signal Uc are switched and then enter two rectifier circuits, where they are converted from AC to DC signals. After conversion by the analog-to-digital signal acquisition module, the DC signals are transmitted to the controller for calculation to obtain the displacement of the target.

[0114] Testing and Verification:

[0115] The displacement measurement system based on a diode rectifier circuit and the displacement measurement system using a switching rectifier circuit disclosed in this invention are tested and verified below. The test comparison results are shown in Table 1 below.

[0116] Table 1

[0117]

[0118] The measured results show that the acquisition error of the diode rectifier circuit is only -0.0003. The circuit of the present invention significantly reduces the measurement error in the full range of a certain type of displacement sensor, meeting the accuracy requirement of 0.2%.

[0119] This invention successfully solves the measurement accuracy problem caused by phase difference in displacement measurement systems based on differential transformers by employing a precision rectifier circuit composed of operational amplifiers and diodes. The displacement measurement system disclosed in this invention features high precision, good versatility, and adaptability.

[0120] The technical solution provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

[0121] All of the above-mentioned optional technical solutions can be combined in any way to form optional embodiments of the present invention, and will not be described in detail here.

[0122] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rectifier circuit, characterized in that, include: The first operational amplifier circuit includes: a first operational amplifier, a first input resistor, a first feedback resistor, a first diode, and a second diode. The first input resistor is connected to the inverting input terminal of the first operational amplifier. The first feedback resistor is connected in parallel with the first operational amplifier. The first diode is connected in parallel with the first operational amplifier. The anode of the first diode is connected to the output terminal of the first operational amplifier. The cathode of the first diode is connected to the inverting input terminal of the first operational amplifier. The second diode is connected in series with the first operational amplifier. The cathode of the second diode is connected to the anode of the first diode. The anode of the second diode is connected to the first feedback resistor. The second operational amplifier circuit includes: a second operational amplifier, a second input resistor, a third input resistor, and a second feedback resistor. The second operational amplifier circuit is connected in series with the first operational amplifier circuit through the second input resistor. The input terminal of the second input resistor is connected to the anode of the second diode. The output terminal of the second input resistor is connected to the inverting input terminal of the second operational amplifier. The third input resistor is connected to the inverting input terminal of the second operational amplifier. The second feedback resistor is connected in parallel with the second operational amplifier.

2. The rectifier circuit as described in claim 1, characterized in that, The resistance values ​​of the third input resistor and the second feedback resistor are equal, and the resistance value of the second input resistor is half the resistance value of the first input resistor.

3. The rectifier circuit as described in claim 2, characterized in that, Also includes: The electrical signal input terminal is connected to the input terminal of the first input resistor and the input terminal of the third input resistor; The electrical signal output terminal is connected to the output terminal of the second operational amplifier. The second diode is adapted to be cut off when the input electrical signal at the electrical signal input terminal is a negative half-axis electrical signal, and to be turned on when the input electrical signal at the electrical signal input terminal is a positive half-axis electrical signal, so that the electrical signal output terminal outputs a positive half-axis DC electrical signal.

4. The rectifier circuit as described in claim 1, characterized in that, The resistance values ​​of the first input resistor and the first feedback resistor are both equal to the resistance value of the third input resistor.

5. A displacement measurement method, characterized in that, include: An excitation electrical signal is sent to a differential transformer, which is connected to the target under test; The system receives a first feedback signal and a second feedback signal generated after the differential transformer receives the excitation signal; it then uses the rectifier circuit described in any one of claims 1-4 to rectify the first and second feedback signals; and finally calculates the displacement of the target under test based on the rectified first and second feedback signals.

6. The displacement measurement method as described in claim 5, characterized in that, The rectification of the first feedback signal and the second feedback signal includes: when the negative half-axis electrical signal of the first feedback signal is input to the rectifier circuit, the second diode in the rectifier circuit is cut off; when the positive half-axis electrical signal of the first feedback signal is input to the rectifier circuit, the second diode in the rectifier circuit is turned on, and the rectifier circuit outputs the positive half-axis DC electrical signal of the first feedback signal; when the negative half-axis electrical signal of the second feedback signal is input to the rectifier circuit, the second diode in the rectifier circuit is cut off; when the positive half-axis electrical signal of the second feedback signal is input to the rectifier circuit, the second diode in the rectifier circuit is turned on, and the rectifier circuit outputs the positive half-axis DC electrical signal of the second feedback signal.

7. The displacement measurement method as described in claim 5, characterized in that, The step of calculating the motion displacement of the target under test based on the rectified first feedback electrical signal and the second feedback electrical signal includes: calculating the sum-difference ratio of the first feedback electrical signal and the second feedback electrical signal; and determining the motion displacement of the target under test based on the sum-difference ratio.

8. A displacement measurement system, characterized in that, include: A communication module is used to send an excitation electrical signal to a differential transformer, wherein the differential transformer is connected to the target under test, and to receive a first feedback electrical signal and a second feedback electrical signal generated by the differential transformer after receiving the excitation electrical signal; a rectifier circuit as described in any one of claims 1-4 is used to rectify the first feedback electrical signal and the second feedback electrical signal; a controller is used to calculate the motion displacement of the target under test based on the rectified first feedback electrical signal and the second feedback electrical signal.

9. The displacement measurement system as described in claim 8, characterized in that, Also includes: A direct digital frequency synthesizer is connected to the controller; a zeroing circuit is connected to the direct digital frequency synthesizer; an amplifier circuit is connected to the zeroing circuit at its input and to the differential transformer at its output.

10. The displacement measurement system as described in claim 8, characterized in that, Also includes: The analog-to-digital signal acquisition module is connected to the rectifier circuit and the controller.

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