Displacement sensor sine wave excitation generation and overcurrent protection circuit

Abstract

The invention provides a sine wave excitation generation and overcurrent protection circuit of a displacement sensor, which relates to the technical field of airborne displacement sensors and comprises a second-order filter circuit, a blocking circuit, a proportional amplification circuit and a push-pull output circuit. The input of the second-order filter circuit is connected with an input square wave signal, and the second-order filter circuit is used for performing second-order low-pass filtering on the square wave signal; the input of the blocking circuit is connected with the output of the second-order filter circuit and is used for filtering a direct current component in the sine wave signal; the input of the proportional amplification circuit is connected with the output of the blocking circuit, and the proportional amplification circuit is used for conditioning the amplitude of the processed sine wave signal; and the input of the push-pull output circuit is connected with the output of the proportional amplification circuit and is used for improving the driving output capability so as to output a sensor excitation sine wave signal meeting the sensor excitation driving capability requirement. The circuit design structure is simple, the cost is low, hardware closed-loop control is adopted, the response speed is high, excitation signal output and overcurrent cut-off can be effectively carried out, and the precision of the output signal is not affected.

Description

Technical Field

[0001] The invention relates to the technical field of airborne displacement sensors, and in particular to a displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit. Background Art

[0002] In airborne control systems, it is often necessary to collect position changes of components such as angular displacement or linear displacement, such as the opening detection of the guide vanes on the inlet of aircraft engines and the opening detection of anti-surge valves. The displacement sensor is a metal sensing device that converts mechanical displacement into an electrical signal output that is linear or has an arbitrary function relationship with it through a potentiometer element. It has the characteristics of high accuracy, wide measurement range, good stability and reliability, and is widely used in airborne measurement systems. The sinusoidal wave excitation signal of the displacement sensor has a great influence on the acquisition accuracy and stability. At the same time, it is also necessary to be able to realize the sensor excitation overcurrent protection function to avoid damaging the sensitive components of the displacement sensor.

[0003] At present, the most common displacement sensor sinusoidal wave excitation output form mainly uses CPU / FPGA and DA control, with complex circuit structure and high system cost. Fault detection and overcurrent protection rely on the coordination mechanism of hardware detection, fault reporting and software control. The response time is long and there is no automatic overcurrent protection measure to ensure the normal operation of the displacement sensor sensitive components. Therefore, the practical application is limited. Summary of the invention

[0004] In view of this, an embodiment of the present application provides a displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit. The circuit design has a simple structure and low cost, adopts hardware closed-loop control, has a fast response speed, can effectively output excitation signals and cut off overcurrent without affecting the output signal accuracy.

[0005] The embodiment of the present application provides the following technical solutions: a displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit, comprising: a second-order filter circuit, a DC isolation circuit, a proportional amplifier circuit and a push-pull output circuit;

[0006] The input end of the second-order filter circuit is connected to the input square wave signal, and is used to perform second-order low-pass filtering on the square wave signal to generate a sine wave signal that meets the sensor excitation frequency;

[0007] The input end of the DC isolation circuit is connected to the output end of the second-order filter circuit, and is used to filter out the DC component in the sinusoidal wave signal so that the sinusoidal wave takes the zero level as the symmetry axis;

[0008] The input end of the proportional amplifier circuit is connected to the output end of the DC isolation circuit, and is used to adjust the amplitude of the sine wave signal processed by the DC isolation circuit so that the amplitude of the sine wave signal meets the sensor sine wave excitation amplitude range;

[0009] The input end of the push-pull output circuit is connected to the output end of the proportional amplifier circuit, and is used to improve the driving output capability, so as to output a sensor excitation sinusoidal wave signal that meets the sensor excitation driving capability requirements.

[0010] According to an embodiment of the present application, the circuit further includes a protection circuit, the input end of the protection circuit is connected to the output end of the push-pull output circuit, and the output end of the protection circuit is connected to the output end of the DC isolation circuit;

[0011] The protection circuit includes a current acquisition circuit, a differential amplifier circuit and a conditioning and offset circuit, wherein the input end of the current acquisition circuit is connected to the output end of the push-pull output circuit, and is used to perform overcurrent detection on the sensor excitation sine wave signal output by the push-pull output circuit;

[0012] The input end of the differential amplifier circuit is connected to the output end of the current acquisition circuit, and is used to compare the voltage difference between the two ends of the current sampling resistor in the current acquisition circuit and amplify it;

[0013] The input end of the conditioning and compensation circuit is connected to the output end of the differential amplifier circuit, and the output end of the conditioning and compensation circuit is connected to the output end of the DC isolation circuit, so as to process the voltage difference generated by the differential amplifier circuit to generate a sine wave signal with completely opposite phases and whose amplitude automatically changes according to the voltage difference. The sine wave signal is superimposed on the output of the DC isolation circuit to adaptively adjust the amplitude of the output excitation and ensure that the excitation output is automatically cut off when overcurrent occurs.

[0014] According to one embodiment of the present application, the second-order filtering circuit includes a first-order second-order filtering circuit and a second-order second-order filtering circuit connected in sequence, the first-order second-order filtering circuit is connected to the input square wave signal to filter the square wave signal into a triangular wave signal, and the second-order second-order filtering circuit is used to filter the triangular wave signal into a sine wave signal.

[0015] According to an embodiment of the present application, the first-order second-order filtering circuit includes a resistor R1, a resistor R2, a capacitor C1, a capacitor C2 and an op amp D1, one end of the resistor R1 is connected to the input square wave signal, the other end of the resistor R1 is respectively connected to one end of the resistor R2 and one end of the capacitor C1, the other end of the capacitor C1 is connected to the output end of the op amp D1 and the input - end of the op amp D1, the other end of the resistor R2 is connected to the input + end of the op amp D1 and one end of the capacitor C2, and the other end of the capacitor C2 is grounded.

[0016] According to an embodiment of the present application, the secondary second-order filter circuit includes a resistor R3, a resistor R4, a capacitor C3, a capacitor C4 and an op amp D2, one end of the resistor R3 is connected to the output end of the op amp D1, the other end of the resistor R3 is respectively connected to one end of the resistor R4 and one end of the capacitor C3, the other end of the capacitor C3 is connected to the output end of the op amp D2 and the input - end of the op amp D2, the other end of the resistor R4 is connected to the input + end of the op amp D2 and one end of the capacitor C4, and the other end of the capacitor C4 is grounded.

[0017] According to an embodiment of the present application, the DC isolation circuit includes a capacitor C5 and a resistor R5, one end of the capacitor C5 is connected to the output end of the operational amplifier D2, the other end of the capacitor C5 is connected to one end of the resistor R5, and the other end of the resistor R5 is grounded.

[0018] According to an embodiment of the present application, the proportional amplifier circuit includes a resistor R6, a resistor R8 and an operational amplifier D3, one end of the resistor R6 is connected to one end of the resistor R5 and one end of the capacitor C5, the other end of the resistor R6 is connected to the input - end of the operational amplifier D3 and one end of the resistor R8, the other end of the resistor R8 is used as a sensor excitation signal output, and the input + end of the operational amplifier D3 is grounded.

[0019] According to an embodiment of the present application, the push-pull output circuit includes a resistor R7, a transistor V1 and a transistor V2, one end of the resistor R7 is respectively connected to the base of the transistor V1 and the transistor V2, and is also connected to the output end of the operational amplifier D3, the collector of the transistor V1 is connected to +15V, the collector of the transistor V2 is connected to -15V, the emitter of the transistor V1 is connected to the emitter of the transistor V2, and is also connected to the other end of the resistor R7.

[0020] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of this specification include at least: a displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit in the embodiment of the present invention adopts a sinusoidal wave generation circuit and an overcurrent automatic protection circuit, which can have both displacement sensor excitation output capability and overcurrent automatic cutoff protection capability. The present invention is simple in design, easy to implement, low in cost, fast in response speed, can effectively output excitation signals and cut off overcurrent without affecting the accuracy of the output signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a functional block diagram of a displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit according to an embodiment of the present invention;

[0023] Figure 2 It is a hardware schematic diagram of a displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0025] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0026] like Figure 1 As shown, an embodiment of the present invention provides a displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit, including: a second-order filter circuit, a DC isolation circuit, a proportional amplifier circuit and a push-pull output circuit;

[0027] The input end of the second-order filtering circuit is connected to the input square wave signal, which is used to perform second-order low-pass filtering on the square wave signal that meets the sensor sine wave excitation frequency range to generate a sine wave signal that meets the sensor excitation frequency; the input end of the DC isolation circuit is connected to the output end of the second-order filtering circuit, which is used to filter out the DC component in the sine wave signal processed by the second-order filtering circuit, so that the sine wave takes the zero level as the symmetry axis; the input end of the proportional amplifier circuit is connected to the output end of the DC isolation circuit, which is used to adjust the amplitude of the sine wave signal processed by the DC isolation circuit, so that the amplitude of the sine wave signal meets the sensor sine wave excitation amplitude range; the input end of the push-pull output circuit is connected to the output end of the proportional amplifier circuit, which is used to improve the driving output capability and make up for the lack of driving capability of the operational amplifier, so as to output the sensor excitation sine wave signal that meets the sensor excitation driving capability requirements.

[0028] In some embodiments of the present invention, the circuit further includes a protection circuit, an input end of the protection circuit is connected to an output end of the push-pull output circuit, and an output end of the protection circuit is connected to an output end of the DC isolation circuit.

[0029] According to one embodiment, the protection circuit includes a current acquisition circuit, a differential amplifier circuit and a conditioning and compensation circuit. The input end of the current acquisition circuit is connected to the output end of the push-pull output circuit, and is used to perform overcurrent detection on the sensor excitation sinusoidal wave signal output by the push-pull output circuit.

[0030] The input end of the differential amplifier circuit is connected to the output end of the current acquisition circuit, and is used to compare the voltage difference between the two ends of the current sampling resistor in the current acquisition circuit at the excitation output position and amplify it.

[0031] The input end of the conditioning and compensation circuit is connected to the output end of the differential amplifier circuit, and the output end of the conditioning and compensation circuit is connected to the output end of the DC isolation circuit, so as to process the voltage difference generated by the differential amplifier circuit to generate a sine wave signal with completely opposite phases and whose amplitude automatically changes according to the voltage difference. The sine wave signal is superimposed on the output of the DC isolation circuit to adaptively adjust the amplitude of the output excitation and ensure that the excitation output is automatically cut off when overcurrent occurs.

[0032] According to one embodiment, the second-order filtering circuit includes a first-order second-order filtering circuit and a second-order second-order filtering circuit connected in sequence, the first-order second-order filtering circuit is connected to the input square wave signal to filter the square wave signal into a triangular wave signal, and the second-order second-order filtering circuit is used to filter the triangular wave signal into a sine wave signal; wherein, the selection of the cutoff frequency of the filtering circuit is determined by the sensor excitation frequency requirement.

[0033] like Figure 2As shown, according to an embodiment, the first-order second-order filtering circuit includes a resistor R1, a resistor R2, a capacitor C1, a capacitor C2 and an operational amplifier D1, one end of the resistor R1 is connected to the input square wave signal, the other end of the resistor R1 is respectively connected to one end of the resistor R2 and one end of the capacitor C1, the other end of the capacitor C1 is connected to the output end of the operational amplifier D1 and the input - end of the operational amplifier D1, the other end of the resistor R2 is connected to the input + end of the operational amplifier D1 and one end of the capacitor C2, and the other end of the capacitor C2 is grounded.

[0034] According to one embodiment, the secondary second-order filter circuit includes a resistor R3, a resistor R4, a capacitor C3, a capacitor C4 and an op amp D2, one end of the resistor R3 is connected to the output end of the op amp D1, the other end of the resistor R3 is respectively connected to one end of the resistor R4 and one end of the capacitor C3, the other end of the capacitor C3 is connected to the output end of the op amp D2 and the input - end of the op amp D2, the other end of the resistor R4 is connected to the input + end of the op amp D2 and one end of the capacitor C4, and the other end of the capacitor C4 is grounded.

[0035] According to an embodiment, the DC isolation circuit is composed of a capacitor connected in series in the circuit, and the DC component in the sine wave signal is isolated. In this embodiment, the DC isolation circuit includes a capacitor C5 and a resistor R5, one end of the capacitor C5 is connected to the output end of the operational amplifier D2, the other end of the capacitor C5 is connected to one end of the resistor R5, and the other end of the resistor R5 is grounded.

[0036] According to an embodiment, the proportional amplification circuit is composed of an operational amplifier and a matching resistor, and the selection of the amplification factor is determined by the sensor excitation amplitude requirement. In this embodiment, the proportional amplification circuit includes a resistor R6, a resistor R8 and an operational amplifier D3, one end of the resistor R6 is connected to one end of the resistor R5 and one end of the capacitor C5, the other end of the resistor R6 is connected to the input-end of the operational amplifier D3 and one end of the resistor R8, the other end of the resistor R8 is used as the sensor excitation signal output, and the input+end of the operational amplifier D3 is grounded.

[0037] According to an embodiment, the push-pull output circuit is composed of a PNP transistor, an NPN transistor and a resistor. The transistor realizes the push-pull output function and improves the circuit driving capability. The resistor realizes the blind area conduction function and provides a signal path before the transistor is turned on. In this embodiment, the push-pull output circuit includes a resistor R7, a transistor V1 and a transistor V2. One end of the resistor R7 is connected to the base of the transistor V1 and the transistor V2 respectively, and is connected to the output end of the operational amplifier D3. The collector of the transistor V1 is connected to +15V, and the collector of the transistor V2 is connected to -15V. The emitter of the transistor V1 is connected to the emitter of the transistor V2, and is connected to the other end of the resistor R7.

[0038] According to an embodiment, the current acquisition circuit is composed of a protection resistor, the resistance of which should be much smaller than the internal resistance of the sensor, and the current flowing through is collected and converted into a voltage across the resistor. In this embodiment, the current acquisition circuit includes a resistor R9, one end of which is connected to one end of the resistor R7, the emitter of the transistor V1 and the emitter of the transistor V2, and the other end of the resistor R9 is connected to a resistor R8.

[0039] According to an embodiment, the differential amplifier circuit is composed of an operational amplifier and a matching resistor, so as to realize the collection and amplification of the voltage across the resistor in the current collection circuit. In the embodiment, the differential amplifier circuit includes: a resistor R10, a resistor R11, a resistor R12, a resistor R13, and an operational amplifier D4, one end of the resistor R10 is connected to the resistor R9, the other end of the resistor R10 is connected to the input-end of the operational amplifier D4, one end of the resistor R11 is connected to the other end of the resistor R9, the other end of the resistor R11 is connected to the input+end of the operational amplifier D4, one end of the resistor R12 is connected to the input+end of the operational amplifier D4, the other end of the resistor R12 is grounded, one end of the resistor R13 is connected to the input-end of the operational amplifier D4, and the other end of the resistor R13 is connected to the output of the operational amplifier D4.

[0040] According to one embodiment, the conditioning and cancellation circuit is composed of an operational amplifier, a low-pass filter circuit, and a matching resistor, which realizes the inversion of the input signal and adjusts the signal voltage amplitude at the same time. The proportional coefficient of the adjustment needs to satisfy the following requirements: when the resistor in the current acquisition circuit is completely open due to damage from overcurrent, the signal amplitude output by the conditioning and cancellation circuit should be basically consistent with the excitation amplitude. This signal is superimposed on the output of the DC isolation circuit to realize the function that the sensor excitation is offset and cannot be output when overcurrent occurs. In the embodiment, the conditioning and compensation circuit includes: a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a capacitor C6, and an operational amplifier D5, wherein the input-end of the operational amplifier D5 is connected to the resistor R14, the resistor R17, and the capacitor C6, the input+end of the operational amplifier D5 is connected to the resistor R15, the other end of the resistor R15 is grounded, the other end of the resistor R14 is connected to the output of the operational amplifier D4, the output of the operational amplifier D5 is connected to the resistor R18, the resistor R16, and the resistor R17, the other end of the resistor R16 is connected to the capacitor C6, and the other end of the resistor R18 is connected to the resistor R8, the input-end of the operational amplifier D3, and the resistor R6.

[0041] The specific circuit operation process of the displacement sensor sinusoidal wave excitation generation and overcurrent automatic protection method according to the embodiment of the present invention is as follows:

[0042] Step 1: Calculate the cutoff frequency of the second-order low-pass filter circuit according to the frequency range of sensor excitation to ensure that a single-frequency sine wave signal within the sensor excitation frequency range can be output normally;

[0043] Step 2: Select a DC blocking capacitor to ensure that the DC component of the sine wave can be completely isolated;

[0044] Step 3: Calculate the amplification factor of the proportional amplifier circuit according to the amplitude range of the sensor excitation to ensure that the sine wave signal within the sensor excitation amplitude range can be output normally;

[0045] Step 4: Select appropriate transistors and resistors to ensure that the output of the push-pull circuit meets the sensor driving requirements;

[0046] Step 5: Select a suitable current sampling resistor according to the internal resistance of the sensor;

[0047] Step 6: Select a suitable differential gain to ensure that the output of the operational amplifier will not be saturated even if the current sampling resistor is open circuited;

[0048] Step 7: Select appropriate filter conditioning parameters to ensure that when the current sampling resistor is open, an inverse signal of equal amplitude can be superimposed on the input to offset the excitation output.

[0049] A sensor sinusoidal wave excitation signal generation and overcurrent automatic protection method according to an embodiment of the present invention is used to provide an excitation signal for an airborne displacement sensor and can realize an adaptive overcurrent protection cut-off function. The excitation signal output and overcurrent cut-off can be performed simultaneously without affecting the output signal accuracy.

[0050] The present invention is further described below in conjunction with the accompanying drawings and embodiments. The internal resistance of a certain type of linear displacement sensor is about 1 kΩ, the excitation signal is required to be in the form of a sine wave, the frequency is required to be 2.95 kHz ± 0.05 kHz, and the effective value of the voltage is required to be 6 V ± 10%.

[0051] like Figure 1 , Figure 2 As shown, Figure 1 It is a functional block diagram of the displacement sensor sinusoidal wave excitation generation and overcurrent automatic protection method of the present invention. Figure 2 It is a hardware principle diagram of the displacement sensor sinusoidal wave excitation generation and overcurrent automatic protection method of the present invention.

[0052] Example 1: Combination Figure 1 and Figure 2 ,in Figure 1 It is the overall functional block diagram, which explains the interconnection relationship of each circuit. Figure 2 This is the hardware schematic diagram of the displacement sensor sinusoidal wave excitation generation and overcurrent automatic protection method. Its specific working principle is: for the input high level 5V, low level 0V, frequency 2.9kHz square wave signal, first use the second-order low-pass filter circuit, by configuring resistors R1, R2 and capacitors C1, C2, the first-stage second-order filter circuit cutoff frequency is 2.27kHz, the output is a 2.9kHz triangle wave, by configuring resistors R3, R4 and capacitors C3, C4, the second-stage second-order filter circuit cutoff frequency is 4.1kHz, the output is a 2.9kHz sine wave, the valley value is 0V. After the DC isolation circuit C5 capacitor isolates the DC and passes the AC, the signal is conditioned to a sine wave signal with a frequency of 2.9kHz, a peak-to-peak value of 5.385V, and 0 is the symmetry axis. By configuring resistors R8 and R6 in the proportional amplifier circuit, the amplification factor is 2.7 times, and a sine wave signal with a frequency of 2.9kHz and an effective value of 5.8V is obtained. In the push-pull circuit, V1 is selected as an NPN transistor and V2 is selected as a PNP transistor, which makes up for the insufficient driving capability of the operational amplifier D3. Finally, the displacement sensor excitation signal with a sinusoidal wave excitation frequency of 2.9kHz and an effective value of the excitation voltage of 5.8V is output.

[0053] At the same time, R9 is selected as 10Ω for current sampling. The function of the differential amplifier circuit is to amplify the voltage difference across the current sampling resistor. By configuring the resistors R10, R11, R12 and R13 in the differential amplifier circuit, the amplification factor is 8.2 times. Under normal circumstances, the voltage difference across the resistor is extremely small and can be ignored after amplification. When the overcurrent causes the 10Ω resistor to open, the differential pressure across the two ends increases, and the differential amplifier circuit will generate an amplified output. Under the influence of the conditioning and offset circuit, by configuring R14, R15, R16, R17, R18 and C6, a sinusoidal wave signal with the opposite phase and equal amplitude to the output of the DC isolation circuit will be generated. After superposition, the excitation output is 0, the protection circuit works, and the internal components of the sensor will not be damaged by overcurrent.

[0054] The sensor sine wave excitation generation circuit of the embodiment of the present invention includes a second-order filter circuit, a DC isolation circuit, a proportional amplifier circuit, and a push-pull output circuit, and the overcurrent automatic protection circuit includes a current acquisition circuit, a differential amplifier circuit, and a conditioning offset circuit. The sensor sine wave excitation generation and overcurrent automatic protection circuit of the present invention is an adaptive closed-loop control method. First, the square wave signal within the frequency range that meets the sensor excitation requirements is converted into a sine wave signal, and then the DC component in the signal is removed by the DC isolation circuit. Then, the sine wave amplitude is conditioned by the proportional amplifier circuit so that the excitation output meets the amplitude range required by the sensor excitation, and finally the driving ability is improved by the push-pull amplifier circuit. At the same time, by collecting the output current and performing proportional amplification and filtering conditioning, in the case of output overcurrent, a completely inverted signal with equal amplitude can be automatically generated and superimposed on the front-end excitation output to offset the excitation continued output, avoiding continuous overcurrent to cause greater damage to the output circuit and the sensor. The present invention has been verified by actual use, and can provide a sine wave excitation signal for loads such as displacement sensors, ensure the normal operation of the displacement sensor, and has overcurrent detection and automatic cut-off protection functions, and has a wide range of application value.

[0055] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit, characterized in that: include: Second-order filtering circuit, DC blocking circuit, proportional amplifier circuit and push-pull output circuit; The input end of the second-order filter circuit is connected to the input square wave signal, and is used to perform second-order low-pass filtering on the square wave signal to generate a sine wave signal that meets the sensor excitation frequency; The input end of the DC isolation circuit is connected to the output end of the second-order filter circuit, and is used to filter out the DC component in the sinusoidal wave signal so that the sinusoidal wave takes the zero level as the symmetry axis; The input end of the proportional amplifier circuit is connected to the output end of the DC isolation circuit, and is used to adjust the amplitude of the sine wave signal processed by the DC isolation circuit so that the amplitude of the sine wave signal meets the sensor sine wave excitation amplitude range; The input end of the push-pull output circuit is connected to the output end of the proportional amplifier circuit, and is used to improve the driving output capability, so as to output a sensor excitation sinusoidal wave signal that meets the sensor excitation driving capability requirements.

2. The displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit according to claim 1 is characterized in that: The circuit further comprises a protection circuit, wherein an input end of the protection circuit is connected to an output end of the push-pull output circuit, and an output end of the protection circuit is connected to an output end of the DC isolation circuit; The protection circuit includes a current acquisition circuit, a differential amplifier circuit and a conditioning and offset circuit, wherein the input end of the current acquisition circuit is connected to the output end of the push-pull output circuit, and is used to perform overcurrent detection on the sensor excitation sine wave signal output by the push-pull output circuit; The input end of the differential amplifier circuit is connected to the output end of the current acquisition circuit, and is used to compare the voltage difference between the two ends of the current sampling resistor in the current acquisition circuit and amplify it; The input end of the conditioning and compensation circuit is connected to the output end of the differential amplifier circuit, and the output end of the conditioning and compensation circuit is connected to the output end of the DC isolation circuit, so as to process the voltage difference generated by the differential amplifier circuit to generate a sine wave signal with completely opposite phases and whose amplitude automatically changes according to the voltage difference. The sine wave signal is superimposed on the output of the DC isolation circuit to adaptively adjust the amplitude of the output excitation and ensure that the excitation output is automatically cut off when overcurrent occurs.

3. The displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit according to claim 1, characterized in that: The second-order filtering circuit includes a first-order second-order filtering circuit and a second-order second-order filtering circuit connected in sequence, the first-order second-order filtering circuit is connected to the input square wave signal to filter the square wave signal into a triangular wave signal, and the second-order second-order filtering circuit is used to filter the triangular wave signal into a sine wave signal.

4. The displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit according to claim 3 is characterized in that: The first-order second-order filtering circuit includes a resistor R1, a resistor R2, a capacitor C1, a capacitor C2 and an operational amplifier D1, one end of the resistor R1 is connected to the input square wave signal, the other end of the resistor R1 is respectively connected to one end of the resistor R2 and one end of the capacitor C1, the other end of the capacitor C1 is connected to the output end of the operational amplifier D1 and the input - end of the operational amplifier D1, the other end of the resistor R2 is connected to the input + end of the operational amplifier D1 and one end of the capacitor C2, and the other end of the capacitor C2 is grounded.

5. The displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit according to claim 4, characterized in that: The secondary second-order filter circuit includes a resistor R3, a resistor R4, a capacitor C3, a capacitor C4 and an operational amplifier D2, one end of the resistor R3 is connected to the output end of the operational amplifier D1, the other end of the resistor R3 is respectively connected to one end of the resistor R4 and one end of the capacitor C3, the other end of the capacitor C3 is connected to the output end of the operational amplifier D2 and the input - end of the operational amplifier D2, the other end of the resistor R4 is connected to the input + end of the operational amplifier D2 and one end of the capacitor C4, and the other end of the capacitor C4 is grounded.

6. The displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit according to claim 5, characterized in that: The DC isolation circuit includes a capacitor C5 and a resistor R5, one end of the capacitor C5 is connected to the output end of the operational amplifier D2, the other end of the capacitor C5 is connected to one end of the resistor R5, and the other end of the resistor R5 is grounded.

7. The displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit according to claim 6, characterized in that: The proportional amplifier circuit includes a resistor R6, a resistor R8 and an operational amplifier D3, one end of the resistor R6 is connected to one end of the resistor R5 and one end of the capacitor C5, the other end of the resistor R6 is connected to the input - end of the operational amplifier D3 and one end of the resistor R8, the other end of the resistor R8 is used as a sensor excitation signal output, and the input + end of the operational amplifier D3 is grounded.

8. The displacement sensor sinusoidal wave excitation generation and overcurrent protection circuit according to claim 7, characterized in that: The push-pull output circuit includes a resistor R7, a transistor V1 and a transistor V2, one end of the resistor R7 is connected to the base of the transistor V1 and the transistor V2 respectively, and is also connected to the output end of the operational amplifier D3, the collector of the transistor V1 is connected to +15V, the collector of the transistor V2 is connected to -15V, the emitter of the transistor V1 is connected to the emitter of the transistor V2, and is also connected to the other end of the resistor R7.

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