A passive resonant transformer position sensor

Abstract

The application relates to a passive resonant transformer type position sensor, which comprises an antenna PCB, a target PCB, processing circuitry, an input port and an output port; wherein the target PCB comprises a first copper-clad plate, a first rectangular copper foil target coil, a first external resistance and an external inductance, the antenna PCB comprises a second copper-clad plate, a second rectangular copper foil excitation coil, a multi-period cosine / cosine copper foil receiving coil, a single-period cosine / cosine copper foil receiving coil and a second external resistance; the receiving coil induces a voltage signal, the output port is used for outputting the voltage signal of the receiving coil, and the input port is used for inputting an excitation signal to the antenna PCB; the target PCB is connected to a measured object in linear motion, and there is a gap between the target PCB and the antenna PCB and no contact. Compared with the prior art, the application has the advantages of guaranteeing the accuracy of detection, reducing the cost of the transformer type sensor, improving the service life of the sensor and the like.

Description

Technical Field

[0001] This invention relates to the technical field of position sensors, and in particular to a passive resonant transformer position sensor. Background Technology

[0002] In the industrial manufacturing sector, high-quality and precise production places increasingly higher demands on non-contact position sensors that are highly usable, simple in structure, and highly scalable.

[0003] Current non-contact transformer sensors mainly consist of traditional non-contact rotary transformers and their variants, commonly used for measuring the angular displacement and angular velocity of rotating AC motors. They are a relatively mature type of sensor based on the principle of electromagnetic induction. In linear industrial scenarios such as automated production lines, high-speed material handling, and intelligent logistics sorting, common sensors or sensing systems such as magnetic grating, optical grating, and cross-induction loops, while offering good measurement performance, are expensive and have a limited range of measurable relative speeds. Furthermore, while linear position sensors such as sliding resistors are inexpensive, they suffer from physical friction, have a short lifespan, and require high maintenance, making them unsuitable for accurate measurement under prolonged high-speed motion. Summary of the Invention

[0004] The purpose of this invention is to provide a passive resonant transformer position sensor that ensures detection accuracy, reduces the cost of transformer sensors while increasing sensor lifespan, and enhances the flexibility of sensor application in various scenarios.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A passive resonant transformer position sensor, the sensor includes an antenna PCB, a target PCB, a processing circuit, an input port and an output port;

[0007] The target PCB includes a first copper-clad laminate, a first rectangular copper foil target coil, a first external resistor, and an external inductor. The antenna PCB includes a second copper-clad laminate, a second rectangular copper foil excitation coil, a multi-cycle sine / cosine copper foil receiving coil, a single-cycle sine / cosine copper foil receiving coil, and a second external resistor. The receiving coil induces a voltage signal, the output port is used to output the voltage signal of the receiving coil, and the input port is used to input an excitation signal to the antenna PCB.

[0008] The target PCB is connected to the measured object that is moving in a straight line, and there is a gap between the target PCB and the antenna PCB but they do not contact each other.

[0009] Furthermore, the voltage signal of the receiving coil is:

[0010]

[0011] Among them, u Acos u Asin u Pcos and u Psin Let l represent the expressions for the induced voltage signals output by the receiving coil in single-cycle cosine, single-cycle sine, multi-cycle cosine, and multi-cycle modes, respectively. A l is the period length of a single-cycle sine / cosine copper foil receiving coil. P x is the length of the multi-period sine / cosine copper foil receiving coil. T x represents the position of the first rectangular copper foil target coil. P The position of the second rectangular copper foil excitation coil (22) is given by term C, which is a supplementary correction term for parasitic capacitance coupling.

[0012] Furthermore, the first rectangular copper foil target coil, the first external resistor, and the external inductor constitute the closed resonant circuit of the target PCB.

[0013] Furthermore, the first rectangular copper foil target coil and the second rectangular copper foil excitation coil have the same length.

[0014] Furthermore, the PCB and the target PCB are in a state of relative linear motion during operation.

[0015] Furthermore, the antenna PCB and the target PCB are parallel to each other.

[0016] Furthermore, the antenna PCB and the target PCB are horizontally positioned.

[0017] Furthermore, the input port and output port are located on the antenna PCB.

[0018] Furthermore, the processing circuit outputs an excitation signal and inputs the excitation signal to the antenna PCB through the input port.

[0019] Furthermore, the excitation signal is:

[0020]

[0021] in, Let ω be the amplitude of the excitation signal and ω be the frequency of the excitation signal. Tx The resonant frequency ω of the resonant circuit of the first rectangular copper foil target coil T Equal, φ Tx The phase of the excitation signal.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) This invention can achieve mass production using simple and common PCB printing technology, which is low-cost and ensures that there is no physical contact between the antenna PCB and the target PCB, eliminating friction, resulting in a long service life and high reliability. In addition, the sensor of this invention is a passive sensor, which only needs to apply an excitation signal of a certain frequency to the antenna PCB without supplying power to the target PCB. This simplifies the equipment layout in industrial settings and expands the applicable range of the sensor's measured objects. It also avoids the cumbersome cable laying of traditional power supply methods and increases the flexibility of the sensor in various scenarios.

[0024] (2) In this invention, even at extremely high speeds, the effect of parasitic capacitive coupling on the magnitude of the induced voltage signal is almost negligible. In addition, the non-contact, lossless design meets the position measurement requirements of high-speed moving objects. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the sensor of the present invention.

[0026] Figure 2 This is a structural diagram of the target PCB of the present invention.

[0027] Figure 3 This is a structural diagram of the antenna PCB of the present invention.

[0028] The components include: target PCB 1, antenna PCB 2, processing circuit 3, input port 4, output port 5, first copper-clad board 11, first rectangular copper foil target coil 12, first external resistor 13, external inductor 14, second copper-clad board 21, second rectangular copper foil excitation coil 22, multi-cycle sine / cosine copper foil receiving coil 23, single-cycle sine / cosine copper foil receiving coil 24, and second external resistor 25. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] This invention proposes a passive resonant transformer position sensor, the overall schematic diagram of which is shown below. Figure 1 As shown in the figure. The structure diagrams of the sensor's antenna PCB2 and target PCB1 are shown in the figure. Figure 2 and Figure 3 As shown.

[0031] The present invention proposes a passive resonant transformer position sensor, which includes an antenna PCB2, a target PCB1, a processing circuit 3, an input port 4, and an output port 5;

[0032] The target PCB1 includes a first copper-clad laminate 11, a first rectangular copper foil target coil 12, a first external resistor 13, and an external inductor 14. The antenna PCB2 includes a second copper-clad laminate 21, a second rectangular copper foil excitation coil 22, a multi-cycle sine / cosine copper foil receiving coil 23, a single-cycle sine / cosine copper foil receiving coil 24, and a second external resistor 25. The receiving coil induces a voltage signal, the output port 5 is used to output the voltage signal of the receiving coil, and the input port 4 is used to input an excitation signal to the antenna PCB2.

[0033] The target PCB1 is connected to the measured object that is moving in a straight line. There is a gap between the target PCB1 and the antenna PCB2, but they do not contact each other.

[0034] The sensor of this invention comprises an antenna PCB2 and a target PCB1, which are non-contact and move in a relative linear motion. When an excitation signal is applied to the second rectangular copper foil excitation coil 22 of the antenna PCB2, resonance occurs in the circuit of the first rectangular copper foil target coil 12 of the target PCB1, at which point the sensor begins to operate, inducing a resonant current in the target coil of the target PCB1. The excitation frequency applied to the second rectangular copper foil excitation coil 22 of the antenna PCB2 is equal to the resonant frequency of the target coil of the target PCB1. As the target PCB1 moves linearly along the antenna PCB2, according to the principles of electromagnetic induction and circuit resonance, the first rectangular copper foil target coil 12 of the target PCB1 resonates. Under the interaction of electromagnetic fields, the electromagnetic field energy change is transmitted back to the receiving coil of the antenna PCB with maximum power using the resonance characteristic, generating a regular inductive voltage signal at the same frequency, while filtering out other frequency noise signals. The amplitude of this induced voltage signal is related to the position of the target coil; that is, the envelope amplitude of the induced voltage signal contains the position information of the target PCB. By outputting it to a computing chip for calculation, the required position and velocity data can be obtained. The magnitude of the envelope amplitude of the induced voltage signal generated by the receiving coil of antenna PCB2 contains the position information of target PCB1. By outputting this signal externally, the desired position information can be calculated from it using a certain method. From the relationship between the magnitude of the envelope amplitude of the induced voltage signal generated by the receiving coil of antenna PCB2 and time, the relationship between the position of antenna PCB2 and time can be obtained, and further, velocity information can be obtained through calculus. Therefore, for any linearly moving object, by simply connecting / combining it with target PCB1 through appropriate structural design, its position and velocity can be measured using this sensor.

[0035] The sensor of this invention comprises two main parts: an antenna PCB2 and a target PCB1. The antenna PCB2 is the main measuring component of the sensor. The target PCB1 is fixed or connected to the object being measured, which is moving in a linear motion, through a suitable mechanical structure or other means. The object being measured drives the target PCB1 to move on the antenna PCB2 in this manner, and outputs the position and velocity of the object being measured through electromagnetic induction and circuit resonance principles. When the sensor is working, the antenna PCB2 and the target PCB1 are in a state of relative linear motion, parallel to each other, with a gap but no contact, and both remain horizontal. The antenna PCB2 mainly includes an excitation coil and a receiving coil, as well as a small number of other circuit components and necessary signal input / output ports. The target PCB1 mainly includes a target coil and a small number of other circuit components.

[0036] The present invention has the following advantages:

[0037] 1. This invention is based on the technologically mature rotary transformer and effectively utilizes the circuit resonance principle to achieve high-precision position measurement.

[0038] 2. This invention can achieve mass production using simple and common PCB printing technology, resulting in low cost.

[0039] 3. In the sensor of the present invention, there is no physical contact between the antenna PCB and the target PCB, there is no friction, and the service life is long and the reliability is high.

[0040] 4. The sensor of the present invention is a passive sensor, which only needs to apply an excitation signal of a certain frequency to the antenna PCB without supplying power to the target PCB. On the one hand, it simplifies the equipment layout in the industrial field, and on the other hand, it expands the applicable range of the sensor to be measured, avoids the cumbersome cable laying of the power supply method, and increases the flexibility of the sensor in various scenarios.

[0041] The accuracy of the detection method of this invention is verified below:

[0042] The processing circuit 3 applies an excitation signal to the antenna PCB 2 through the input port 4. This excitation signal has the following functional form:

[0043]

[0044] in The amplitude of the excitation signal is ω. The frequency of this excitation signal is ω. Tx The resonant frequency ω of the resonant circuit of the target coil 12 is equal to T According to electromagnetic field theory, the expression for the current induced in the target coil 12 at resonance can be obtained:

[0045]

[0046] Among them U Tx R is the vector representation of the excitation signal. Tx R T Here, represents the resistance values ​​of external resistors 25 and 13, respectively, and K is the transfer coefficient, used to describe the ability of excitation coil 22 to generate the magnitude of the induced current in target coil 12 under the action of an excitation signal. Subsequently, the induced current in target coil 12 of target PCB 1 generates an alternating electromagnetic field, inducing voltage signals in receiving coils 23 and 24 of antenna PCB 2. Since receiving coils 23 and 24 are multi-cycle and single-cycle coils, respectively, and each has both sine and cosine forms, the final output induced voltage signals have four types, described by the following set of expressions:

[0047]

[0048] From top to bottom, the expressions represent the induced voltage signals output by the receiving coil for single-cycle cosine, single-cycle sine, multi-cycle cosine, and multi-cycle signals, respectively, where l A The period length of the single-cycle sine (cosine) receiving coil 24 is l. P x is the length of the multi-period sine (cosine) receiving coil 23. T The position of the target coil 12 is shown. The last term, C, is a supplementary correction for parasitic capacitance coupling terms. These mainly exist between the excitation coil 22 and the receiving coils 23 and 24, and are in phase with their corresponding induced voltages. They can be eliminated through certain technical means.

[0049] The following explains how this embodiment meets the position measurement requirements of high-speed moving objects. Taking the induced voltage signal of a single-cycle cosine coil as an example, according to circuit principles, the magnitude of its parasitic capacitance coupling term is directly proportional to the moving speed of the target PCB 1 (the first derivative of its position with respect to time):

[0050]

[0051] Taking the excitation signal frequency as a common 1MHz, and the length of the single-cycle sine (cosine) receiving coil as 400mm, and assuming the current target PCB 1 moves at a speed of up to 100m / s, then the following can be calculated:

[0052]

[0053] It is evident that even at extremely high speeds, the influence of parasitic capacitive coupling on the magnitude of the induced voltage signal is negligible. Coupled with the non-contact, lossless design, this embodiment of the invention is highly suitable for measuring the position of objects moving at high speeds for extended periods. As analyzed in this embodiment, the magnitude of the induced voltage signal is related to the position of the target coil; that is, the envelope amplitude of the induced voltage signal contains the position information of the target PCB 1. By sending the four types of voltage signals through output port 5 to the processing chip in the processing circuit 3 for calculation, the position and velocity data of the target PCB 1, i.e., the moving object, can be obtained.

[0054] Furthermore, since the single-cycle sine (cosine) receiving coil 24 and the multi-cycle sine (cosine) receiving coil 23 are arranged in a mixed manner, the output induced voltage signal is also divided into two categories: one is a single-cycle sine (cosine) voltage signal covering the entire length of the antenna PCB 2, and the other is a multi-cycle sine (cosine) voltage signal with multiple coil cycles. The former is used to measure the absolute position of a moving object, and the latter is used to measure the relative position of a moving object. The combination of the two can obtain high-precision measurement results.

[0055] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A passive resonant transformer-type position sensor, characterized in that, The sensor includes an antenna PCB (2), a target PCB (1), a processing circuit (3), an input port (4), and an output port (5); The target PCB (1) includes a first copper-clad laminate (11), a first rectangular copper foil target coil (12), a first external resistor (13), and an external inductor (14). The antenna PCB (2) includes a second copper-clad laminate (21), a second rectangular copper foil excitation coil (22), a multi-cycle sine / cosine copper foil receiving coil (23), a single-cycle sine / cosine copper foil receiving coil (24), and a second external resistor (25). The receiving coil induces a voltage signal, the output port (5) is used to output the voltage signal of the receiving coil, and the input port (4) is used to input the excitation signal to the antenna PCB (2). The target PCB (1) is connected to the measured object that is moving in a straight line. There is a gap between the target PCB (1) and the antenna PCB (2) and they do not contact each other.

2. The passive resonant transformer position sensor according to claim 1, characterized in that, The voltage signal of the receiving coil is: in, , , and These represent the expressions for the induced voltage signals output by the receiving coils for single-cycle cosine, single-cycle sine, multi-cycle cosine, and multi-cycle sine signals, respectively. The period length of the single-cycle sine / cosine copper foil receiving coil (24) is given. The length of the multi-cycle sine / cosine copper foil receiving coil (23) is given. The position of the first rectangular copper foil target coil (12) is given. The position of the second rectangular copper foil excitation coil (22) is given. C The term is a supplementary correction for parasitic capacitance coupling, and the resonant frequency is... .

3. The passive resonant transformer position sensor according to claim 1, characterized in that, The first rectangular copper foil target coil (12), the first external resistor (13) and the external inductor (14) form a closed resonant circuit of the target PCB (1).

4. A passive resonant transformer position sensor according to claim 1, characterized in that, The first rectangular copper foil target coil (12) and the second rectangular copper foil excitation coil (22) have the same length.

5. A passive resonant transformer position sensor according to claim 1, characterized in that, The PCB (2) and the target PCB (1) are in a state of relative linear motion during operation.

6. A passive resonant transformer position sensor according to claim 5, characterized in that, The antenna PCB (2) and the target PCB (1) are parallel to each other.

7. A passive resonant transformer position sensor according to claim 6, characterized in that, The antenna PCB (2) and the target PCB (1) are set horizontally.

8. A passive resonant transformer position sensor according to claim 1, characterized in that, The input port (4) and output port (5) are located on the antenna PCB (2).

9. A passive resonant transformer position sensor according to claim 1, characterized in that, The processing circuit (3) outputs an excitation signal and inputs the excitation signal to the antenna PCB (2) through the input port (4).

10. A passive resonant transformer position sensor according to claim 1, characterized in that, The excitation signal is: in, The amplitude and frequency of the excitation signal are respectively. The resonant frequency of the resonant circuit of the first rectangular copper foil target coil (12) equal, The phase of the excitation signal.

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