An antenna automatic resonance circuit and system thereof

Abstract

The application provides an antenna automatic resonance circuit and a system thereof, which comprises an LPC series resonance circuit, a full-bridge circuit and a microcontroller connected with the LPC series resonance circuit and the full-bridge circuit, wherein the LPC series resonance circuit comprises an electrically connected electronic switch array, a capacitor array and a radio frequency identification antenna, the full-bridge circuit comprises two half-bridge circuits, a resonance current sampling resistor is connected in series in the two half-bridge circuits, the microcontroller samples the current on the resonance current sampling resistor and calculates and judges the resonance state, and the microcontroller dynamically adjusts the different combination quantity of the capacitors in the capacitor array by controlling the on-off of the electronic switch array, so as to realize real-time automatic resonance. By adopting the method of automatically adapting to the change of environmental factors and adjusting the resonance frequency of the antenna, the automatic resonance of the fishway antenna during installation and the whole operation process is realized, manual intervention is not needed, and the automation degree and the measurement reliability of the equipment are improved.

Description

Technical Field

[0001] This invention relates to the field of radio frequency identification technology, and in particular to an automatic resonant antenna circuit and its system. Background Technology

[0002] The main purpose of fishway monitoring is to study the seasonal migration of protected fish species, their ecological patterns, and thus protect rare fish species and aquatic organisms.

[0003] Radio frequency identification (RFID) antennas used in fishways need to be manufactured to specific dimensions and installed and fixed in the waterways according to different river conditions. Furthermore, according to international standards, the antennas must operate at specific frequencies. However, the current problem is:

[0004] (1) Beforehand: Due to the installation process of the antenna, the slight change in the size of the antenna itself, the pH value, salt content, metal content and other factors of the river water will affect the final working parameters of the antenna. It is necessary to manually adjust the equipment resonance parameters after the antenna is installed so that the antenna resonance frequency works at a specific frequency value, which makes the on-site work cumbersome and time-consuming.

[0005] (2) During operation: During the operation of the equipment, the ambient temperature and river water parameters will change slowly, and the antenna may be deformed by external forces, which will cause the antenna operating parameters to change, thus making it impossible for the system to read the electronic tag data in the fish through the antenna. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide an automatic resonant antenna circuit and system thereof, so as to at least solve the shortcomings of the above-mentioned technology.

[0007] This invention proposes an automatic resonant antenna circuit, comprising:

[0008] An automatic resonant antenna circuit is characterized by comprising an LPC series resonant circuit, a full-bridge circuit, and a microcontroller connecting the LPC series resonant circuit and the full-bridge circuit. The LPC series resonant circuit includes an electrically connected array of electronic switches, a capacitor array, and a radio frequency identification antenna. The full-bridge circuit includes two half-bridge circuits, with a resonant current sampling resistor connected in series in each half-bridge circuit. The microcontroller samples and calculates the current across the resonant current sampling resistor to determine the resonant state. By controlling the on / off state of the electronic switch array, the microcontroller dynamically adjusts the number of different combinations of capacitors connected to the RLC circuit in the capacitor array, thereby achieving real-time automatic resonance.

[0009] Furthermore, it also includes a voltage amplification circuit and an analog-to-digital converter. The voltage amplification circuit is connected to the analog-to-digital converter and the resonant current sampling resistor respectively. The microcontroller determines the resonance state through the data output by the voltage amplification circuit and the analog-to-digital converter through the resonant current sampling resistor, calculates or looks up the table to adjust the corresponding capacitance value, and then controls the on / off state of the electronic switch array to connect the corresponding capacitor in the capacitor array into the circuit.

[0010] Furthermore, the capacitor array includes a capacitor group formed by several capacitors connected in parallel and a fixed capacitor connected to the capacitor group. The fixed capacitor is used to set the RLC resonant frequency in a first preset range, and the capacitor group is used to set the RLC resonant frequency in a second preset range, wherein the second preset range is smaller than the first preset range.

[0011] Furthermore, the electronic switch array includes a bidirectional electronic switch, a Zener diode, and a voltage divider resistor. The Zener diode is connected in series with the bidirectional electronic switch, and the voltage divider resistor is connected in series with the Zener diode.

[0012] Furthermore, the half-bridge circuit adopts a top-and-bottom transistor configuration, wherein the top transistor is a P-channel MOSFET transistor and the bottom transistor is an N-channel MOSFET transistor.

[0013] Furthermore, a power resistor is also provided in the full-bridge circuit, which is used to adjust the resonant Q value of the RLC series circuit.

[0014] Furthermore, a half-bridge controller is connected between the microcontroller and both half-bridge circuits.

[0015] The present invention also proposes an automatic antenna resonance system, which is applied to the above-mentioned automatic antenna resonance circuit.

[0016] The automatic antenna resonance circuit and system of this invention determine the resonance state by sampling and calculating the current on the resonant current sampling resistor, and dynamically adjust the number of different combinations of capacitors connected to the RLC circuit in the capacitor array by controlling the on / off state of the electronic switch array, thereby achieving real-time automatic resonance. By adopting a method of automatically adapting to changes in environmental factors and adjusting the resonant frequency of the antenna, the fishway antenna achieves automatic resonance during installation and throughout the entire operation process without manual intervention, thus improving the automation level and measurement reliability of the equipment. Attached Figure Description

[0017] Figure 1 This is a circuit diagram of the antenna automatic resonance circuit in the first embodiment of the present invention;

[0018] Figure 2 This is a circuit diagram of the capacitor array in the first embodiment of the present invention;

[0019] Figure 3 This is a circuit diagram of the electronic switch array in the first embodiment of the present invention;

[0020] Figure 4 This is a circuit diagram of the resonant circuit sampling and amplification circuit in the first embodiment of the present invention;

[0021] Figure 5 This is a circuit diagram of the full-bridge drive circuit in the first embodiment of the present invention;

[0022] Figure 6 This is a circuit diagram of the electronic switch turn-off control circuit in the first embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Electronic switch array; 2. Capacitor array; 3. Radio frequency identification antenna; 4. First half-bridge circuit; 5. Second half-bridge circuit; 6. Power resistor; 7. First half-bridge controller; 8. Second half-bridge controller; 9. Resonant current sampling resistor; 10. Voltage amplifier circuit; 11. Analog-to-digital converter; 12. Electronic switch turn-off control circuit; 13. Microcontroller.

[0025] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0026] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] Example 1

[0029] Please see Figure 1The diagram shows an automatic antenna resonance circuit in the first embodiment of the present invention, including an LPC series resonant circuit, a full-bridge circuit, and a microcontroller 13 connecting the LPC series resonant circuit and the full-bridge circuit. The LPC series resonant circuit includes an electronic switch array 1, a capacitor array 2, and a radio frequency identification antenna 3 electrically connected. The full-bridge circuit includes two half-bridge circuits (a first half-bridge circuit 4 and a second half-bridge circuit 5). A resonant current sampling resistor 9 is connected in series in the two half-bridge circuits. The microcontroller 13 samples the current on the resonant current sampling resistor 9 and calculates and determines the resonance state. By controlling the on / off state of the electronic switch array 1, it dynamically adjusts the number of different combinations of capacitors connected to the RLC circuit in the capacitor array 2 to achieve real-time automatic resonance.

[0030] In this embodiment, such as Figure 2 As shown, the capacitor array 2 includes a capacitor group formed by several capacitors connected in parallel and a fixed capacitor connected to the capacitor group. The fixed capacitor is used to set the RLC resonant frequency within a first preset range, and the capacitor group is used to set the RLC resonant frequency within a second preset range, where the second preset range is smaller than the first preset range. This embodiment uses a combination of 10 capacitors as an example. Capacitors C12 to C23 form the capacitor array 2. C24 and C25 are fixed capacitors that are already present in the RLC series circuit and are used to match the 10 capacitors in the capacitor array 2. Essentially, C24 and C25 are used for coarse adjustment, setting the RLC resonant frequency within a rough range. Fine adjustment is then achieved through different combinations of the 10 capacitors C12 to C23. Ten capacitors can be combined to produce 2^10 = 1024 possible output values. For example, using the E12 standard, the capacitor values ​​are: 1.0nF, 1.2nF, 1.5nF, 1.8nF, 2.2nF, 3.3nF, 3.9nF, 4.7nF, 5.6nF, and 6.8nF. Through permutation and combination, the range of these 1024 possible capacitor values ​​can be calculated to be 1nF to 32nF. After removing duplicates, 262 values ​​remain. Therefore, the resolution of the capacitor combinations is... The resolution meets the automatic resonance requirements of the system. In practice, the value of the capacitor combination can be calculated in the microcontroller 13 by an algorithm. Taking a combination of 10 capacitors as an example, two arrays are set as the capacitor value array C

[10] and the coefficient array a

[10] . C

[10] stores the 10 capacitor values ​​according to the priority number rule, and a

[10] stores the binary code corresponding to 0 to 1023 composed of 10 "1"s or "0". Then, the 1024 resistor combination values ​​are calculated by a loop program.

[0031] In some optional implementations, the deduplicated capacitance values ​​can be pre-calculated by software and stored in the program of the microcontroller 13. Then, the required capacitance combination values ​​can be selected by looking up a table. To ensure stability and high voltage resistance, metallized polypropylene film capacitors are selected.

[0032] Furthermore, the electronic switch array 1 includes a bidirectional electronic switch, a Zener diode, and a voltage divider resistor. The Zener diode is connected in series with the bidirectional electronic switch, and the voltage divider resistor is connected in series with the Zener diode. Figure 3 As shown, one of the bidirectional electronic switches consists of two power N-channel MOSFETs Q9 and Q10 combined back-to-back to form a common-source electronic switch. D5 is a Zener diode, providing a stable turn-on voltage for Q9 and Q10. The enable signal of the electronic switch is controlled by microcontroller 13 through CAP_EN3. When the electronic switch is turned on, CAP_EN3 is high, Q20 and Q15 are turned on, and the power supply VCC_MOS_EN is applied to D5 through Q20 and the two voltage divider resistors R17 and R18. D5 then forms a circuit with the resonant circuit ground through the body diode of Q9 or Q10, thus enabling D5 to work and turning on the electronic switch. The other electronic switches in the electronic switch array 1 are connected to... Figure 3 Similarly, electronic switches can also be implemented using power relays or optoelectronic solid-state relays.

[0033] Furthermore, the antenna automatic resonance circuit in this embodiment also includes a voltage amplifier circuit 10 and an analog-to-digital converter 11. The voltage amplifier circuit 10 is connected to the analog-to-digital converter 11 and the resonant current sampling resistor 9. The microcontroller 13 determines the resonance state through the data output by the voltage amplifier circuit 10 and the analog-to-digital converter 11 via the resonant current sampling resistor 9, calculates or looks up the corresponding capacitance value to adjust, and then controls the electronic switch array 1 to open and close, connecting the corresponding capacitor in the capacitor array 2 into the circuit.

[0034] like Figure 4 As shown, the main function of the voltage amplifier circuit 10 is to amplify the small voltage across the resonant current sampling resistor 9r0 to a size suitable for the measurement range of the analog-to-digital converter 11. This can be achieved using a differential amplifier with a certain gain. The analog-to-digital converter 11 is mainly responsible for sampling the output voltage of the voltage amplifier circuit 10 and digitizing it for output to the microcontroller 13. Since one section of the resonant current sampling resistor 9r0 is grounded, the voltage signal across it is a half-wave rectified signal, i.e. Because it is necessary to identify the maximum value in the time domain signal, the sampling rate of the analog-to-digital converter 11 needs to be more than 10 times the frequency of the LRC resonant circuit. In this embodiment, the analog-to-digital converter 11 is selected with 12-bit or 16-bit precision.

[0035] Specifically, in this embodiment, the radio frequency identification antenna 3 is wound with enameled wire of appropriate cross-sectional area according to the requirements of the river channel size and the magnitude of the operating current. The winding parameters are mainly the inductance L and the DC resistance RL. Generally, the larger the inductance (the more turns wound), the higher the sensitivity of identifying the electronic tag inside the fish species. However, the loss caused by the DC resistance will also increase. Therefore, it is necessary to select an appropriate inductance L. The coil needs to pass through a PVC pipe of a customized size (rectangular or other shaped) in order to fix and protect the antenna.

[0036] In this embodiment, a half-bridge controller (first half-bridge controller 7 and second half-bridge controller 8) is connected between the microcontroller 13 and both half-bridge circuits. A power resistor 6 is also provided in the full-bridge circuit. Figure 5 As shown, the half-bridge circuit uses a dual-transistor configuration, where the upper transistor is a P-channel MOSFET and the lower transistor is an N-channel MOSFET. The power resistor 6 is used to adjust the resonant Q value of the RLC series circuit. Figure 5 In the circuit, R103 is a power resistor with a current of 6 ohms. The resonant circuit has the maximum current, and its power P is... R =I 2 Therefore, a high-power resistor 6 needs to be selected. In this embodiment, an aluminum-cased resistor is selected, and a suitable heat sink is also considered. The half-bridge controller uses two dual-channel high-speed power MOSFET drivers to drive the full-bridge circuit. The full-bridge drive signal is provided by the microcontroller 13.

[0037] like Figure 5 As shown, the resonant current sampling resistor 9R108 primarily functions to sample the resonant current. Similarly, its power is determined according to P. R = I 2 *r0 calculation: the resonant current is in the ampere level, so a suitable power package needs to be selected; in order to reduce the influence of the resonant current sampling resistor 9 on the LRC series circuit, the resistance value of r0 is generally between 10 and 50 milliohms.

[0038] In this embodiment, the electronic switch off control circuit 12 is as follows: Figure 6 As shown, because after the electronic switch is turned on, when Figure 2 After the enable signal of CAP_EN3 is pulled low, although Q15 is turned off, it cannot be turned off immediately because C6 and the gate-source capacitor in the MOSFET store a certain voltage. Therefore, through... Figure 6 The U3 in the process is quickly shut down, and the control signal of the U3 comes from the microcontroller 13.

[0039] In summary, the automatic antenna resonance circuit in the above embodiments of the present invention achieves real-time automatic resonance by sampling and calculating the current on the resonant current sampling resistor, and dynamically adjusting the number of different combinations of capacitors connected to the RLC circuit in the capacitor array by controlling the on / off state of the electronic switch array. By adopting a method of automatically adapting to changes in environmental factors and adjusting the resonant frequency of the antenna, the fishway antenna achieves automatic resonance during installation and throughout the entire operation process without manual intervention, thus improving the automation level and measurement reliability of the equipment.

[0040] Example 2

[0041] In another aspect, the present invention also proposes an automatic antenna resonance system for use in the aforementioned automatic antenna resonance circuit.

[0042] The automatic antenna resonance system provided in this embodiment of the invention has the same implementation principle and technical effect as the aforementioned method embodiment. For the sake of brevity, any parts not mentioned in the system embodiment can be referred to the corresponding content in the aforementioned method embodiment.

[0043] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An automatic resonant antenna circuit, characterized in that it comprises an LPC series resonant circuit, a full-bridge circuit, and a microcontroller connecting the LPC series resonant circuit and the full-bridge circuit, wherein the LPC series resonant circuit comprises an electronic switch array, a capacitor array, and a radio frequency identification antenna electrically connected, the capacitor array comprises a capacitor group formed by several capacitors connected in parallel and a fixed capacitor connected to the capacitor group, wherein the fixed capacitor is used to set the RLC resonant frequency in a first preset range, the capacitor group is used to set the RLC resonant frequency in a second preset range, the second preset range being smaller than the first preset range, the full-bridge circuit comprises two half-bridge circuits, a resonant current sampling resistor is connected in series in the two half-bridge circuits, and a half-bridge controller is connected between the microcontroller and the two half-bridge circuits; The antenna automatic resonance circuit also includes a voltage amplifier circuit and an analog-to-digital converter. The voltage amplifier circuit is connected to the analog-to-digital converter and the resonant current sampling resistor. The microcontroller determines the resonance state by the data output from the voltage amplifier circuit and the analog-to-digital converter through the resonant current sampling resistor. By controlling the on / off state of the electronic switch array, the microcontroller dynamically adjusts the number of different combinations of capacitors connected to the RLC circuit in the capacitor array to achieve real-time automatic resonance. The capacitor bank uses E12 standard capacitance values, which are as follows: 1.0nF, 1.2nF, 1.5nF, 1.8nF, 2.2nF, 3.3nF, 3.9nF, 4.7nF, 5.6nF, 6.8nF. Through permutations and combinations, 1024 possible capacitance values ​​were calculated, ranging from 1nF to 32nF. After removing duplicates, 262 values ​​remained. The resolution of this capacitor array combination is... .

2. The antenna automatic resonance circuit according to claim 1, characterized in that, The electronic switch array includes a bidirectional electronic switch, a Zener diode, and a voltage divider resistor. The Zener diode is connected in series with the bidirectional electronic switch, and the voltage divider resistor is connected in series with the Zener diode.

3. The antenna automatic resonance circuit according to claim 1, characterized in that, The half-bridge circuit uses a dual-transistor configuration, where the upper transistor is a P-channel MOSFET and the lower transistor is an N-channel MOSFET.

4. The antenna automatic resonance circuit according to claim 1, characterized in that, The full-bridge circuit also includes a power resistor, which is used to adjust the resonant Q value of the RLC series circuit.

5. An automatic antenna resonance system, applied to an automatic antenna resonance circuit, characterized in that, The antenna automatic resonance circuit is the antenna automatic resonance circuit according to any one of claims 1-4.

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