Programmable automatic impedance matching system

Abstract

The utility model discloses a programmable automatic impedance matching system, including VI detector, control processing unit and matching network, VI detector is used for real -time acquisition impedance value and reflection coefficient value of matching network input end, and will acquire real -time output information to control processing unit, the matching network includes fixed inductance and two capacitor arrays connected respectively in fixed inductance input and output, the capacitor array includes a plurality of different capacitance capacitors, a plurality of capacitor parallelly connected is arranged, and every capacitor branch has a radio frequency switch in series, control processing unit has stored the corresponding relation of impedance value and network topology structure, is used for according to corresponding relation and VI detector real -time output information control relevant radio frequency switch on -off to adjust network topology structure of matching network. The utility model has realized the impedance control of automation.

Description

Technical Field

[0001] This utility model relates to the field of radio frequency circuit technology, and in particular to a programmable automatic impedance matching system. Background Technology

[0002] In radio frequency (RF) energy applications (such as RF heating, wireless power supply, and RF welding), the source impedance is typically fixed at 50 ohms, while the load impedance fluctuates continuously due to changes in operating conditions (such as material condition, distance offset, and equipment aging). When the load impedance and source impedance are mismatched, the RF signal will be reflected, leading to decreased energy transmission efficiency, severe equipment overheating, and even damage to the RF source.

[0003] Traditional impedance matching methods are mostly manual, relying on the operator's experience for repeated adjustments, which is inefficient and cannot adapt well to dynamically changing loads.

[0004] Based on this, the present invention proposes a programmable automatic impedance matching system to solve the problems mentioned above. Utility Model Content

[0005] The purpose of this invention is to provide a programmable automatic impedance matching system to achieve automated impedance control.

[0006] To solve the above-mentioned technical problems, this utility model provides a programmable automatic impedance matching system, including a VI detector, a control processing unit, and a matching network; The VI detector is used to acquire the impedance value and reflection coefficient value of the input terminal of the matching network in real time, and output the acquired information to the control processing unit in real time. The matching network includes a fixed inductor and two capacitor arrays connected to the input and output terminals of the fixed inductor respectively; the capacitor arrays include multiple capacitors with different capacitance values, the multiple capacitors are connected in parallel, and an RF switch is connected in series on each branch of the capacitor. The control processing unit stores the correspondence between impedance values ​​and network topology, and is used to control the on / off state of relevant radio frequency switches according to the correspondence and the information output in real time by the VI detector to adjust the network topology of the matching network.

[0007] Furthermore, the control processing unit includes a core controller and a drive circuit; The core controller is used to generate a control signal to adjust the current network topology to the target network topology corresponding to the current impedance value when the reflection coefficient value output by the current VI detector exceeds the threshold. The drive circuit is used to convert the control signal generated by the core controller into a drive signal to control the operation of the radio frequency switch.

[0008] Furthermore, the VI detector includes a voltage coupler, a current sensor, and an amplitude and phase detection chip; The voltage coupler is used to sample radio frequency voltage signals; The current sensor is used to sample radio frequency current signals; The amplitude and phase detection chip is used to convert voltage and current signals into in-phase DC component voltage and quadrature DC component voltage.

[0009] Furthermore, the current sensor employs a Rogowski coil.

[0010] Furthermore, the capacitance of the capacitor array is designed with binary weighting for the capacitance of its multiple capacitors.

[0011] Furthermore, the RF switch employs one of the following: a high-speed PIN diode, a MEMS RF switch, and a high-voltage GaN FET.

[0012] Furthermore, the programmable automatic impedance matching system also includes a protection circuit, which is electrically connected to the control processing unit to implement overcurrent, overvoltage and overtemperature protection.

[0013] Compared with the prior art, the present invention has at least the following beneficial effects: The programmable automatic impedance matching system provided by this utility model includes a VI detector, a control processing unit, and a matching network. The control processing unit can automatically adjust the network topology of the matching network according to the real-time signal output by the VI detector, thereby achieving automated impedance control and effectively improving the efficiency, stability, and process consistency of high-RF energy applications. Attached Figure Description

[0014] Figure 1 This is the overall circuit diagram of the programmable automatic impedance matching system in this embodiment of the present invention. Detailed Implementation

[0015] The programmable automatic impedance matching system of this utility model will now be described in more detail with reference to the schematic diagrams, which illustrate preferred embodiments of this utility model. It should be understood that those skilled in the art can modify the utility model described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the utility model.

[0016] The present invention will be described in more detail below by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0017] like Figure 1 As shown in the figure, this utility model embodiment proposes a programmable automatic impedance matching system, including a VI detector, a control processing unit, and a matching network.

[0018] The VI detector is used to acquire the impedance value and reflection coefficient value of the input terminal of the matching network in real time, and output the acquired information to the control processing unit in real time.

[0019] The matching network includes a fixed inductor and two capacitor arrays connected to the input and output terminals of the fixed inductor, respectively; the capacitor arrays include multiple capacitors with different capacitance values, the multiple capacitors are connected in parallel, and an RF switch is connected in series on each branch of the capacitor.

[0020] The control processing unit stores the correspondence between impedance values ​​and network topology, and is used to control the on / off state of relevant radio frequency switches according to the correspondence and the information output in real time by the VI detector to adjust the network topology of the matching network.

[0021] In this embodiment, the VI detector is responsible for accurately measuring the radio frequency signal parameters at the input of the matching network, including the radio frequency voltage V, current A and its phase difference θ. Then, based on the collected information, it calculates and outputs the impedance value and reflection coefficient value at the input of the matching network.

[0022] Specifically, the VI detector 1 includes a voltage coupler, a current sensor, and an amplitude and phase detection chip.

[0023] Among them, the voltage coupler can be a high-resistance capacitive voltage divider or a low-coupling directional coupler, used to sample the radio frequency voltage signal; the current sensor uses a Rogowski coil or a Hall effect-based sensor to sample the radio frequency current signal. The Rogowski coil is preferred because it has no magnetic saturation, fast response, and small phase error; the amplitude and phase detection IC uses an integrated IQ demodulator or a dedicated radio frequency detection chip (such as ADI's AD8302 / ADL5511). These chips can convert the voltage signal and the current signal into in-phase DC component voltage I and quadrature DC component voltage Q.

[0024] The impedance and reflection coefficient are calculated by collecting the in-phase DC component voltage I and the quadrature DC component voltage Q. The formula for calculating the impedance is as follows: Impedance magnitude: |Z| = V_rms / I_rms; Impedance phase: θ = arctan(Q / I); Complex impedance: Z = R + jX = |Z| * (cosθ + j*sinθ).

[0025] In this embodiment, the matching network is responsible for performing the actual impedance transformation. It uses two capacitor arrays to connect the input and output terminals of the fixed inductor respectively, so that the matching network forms a "π"-shaped network structure. The layout of the "π"-shaped network structure realizes impedance transformation with "wide range, high precision, and low loss". Its design takes into account both radio frequency characteristics (low loss, wide frequency response) and digital control requirements (programmable, fast response), perfectly adapting to the scenario of "dynamic load change" in radio frequency energy applications, and providing a hardware foundation for real-time automatic control.

[0026] Among them, the fixed inductor is a carefully selected air-core or magnetic core inductor with high Q value and low DCR, based on the target frequency band (such as industrial frequency points such as 13.56MHz or 27.12MHz) and power level. Its value is fixed and provides the main inductive tuning range.

[0027] The capacitor array uses a binary weighted design for the capacitance of its multiple capacitors (such as 1pF, 2pF, 4pF, 8pF, 16pF, etc.), which can achieve the finest stepping and the widest tuning range with the fewest number of switches.

[0028] The RF switch employs one of the following: high-speed PIN diode, MEMS RF switch, or high-voltage GaN FET. The advantage of high-speed PIN diodes is their fast switching speed (microseconds), but they suffer from losses and require bias circuitry. MEMS RF switches offer extremely low insertion loss and good linearity, but are expensive and have weak electrostatic discharge (ESD) immunity. High-voltage GaN FETs are suitable for high-power applications and can be used as ideal RF switches.

[0029] In this embodiment, the control processing unit is the brain of the system, responsible for decision-making and control, and includes a core controller and drive circuits.

[0030] The core controller is used to generate a control signal to adjust the current network topology to the target network topology corresponding to the current impedance value when the reflection coefficient value output by the current VI detector 1 exceeds the threshold.

[0031] Specifically, the core controller can be an ARM Cortex-M4 / M7 core MCU with sufficient ADC channels and high-speed computing capabilities, or an FPGA can be used to achieve extreme speed. The FPGA stores the algorithm that implements the above correspondence, such as the Smith chart lookup table method: the optimal combination of switching states corresponding to different load impedance points is generated in advance and stored in the flash memory of the core controller. After the impedance is measured in real time, the state of the closest point is found in the table and applied directly.

[0032] It should be noted that the choice of algorithm is not limited to the Smith chart lookup table method described above. A hill-climbing algorithm can also be used: the core controller slightly changes the state of one capacitor position, observes the direction of change of the reflection coefficient fed back by the VI detector, and gradually searches in the direction of decreasing reflection coefficient.

[0033] The following describes in detail the specific workflow of the programmable automatic impedance matching system provided in the above embodiments.

[0034] (1) Initialization: The system is powered on and the matching network is in a known initial state (e.g., all RF switches are off). (2) Measurement: The VI detector measures and calculates the complex impedance Z_in and reflection coefficient Γ at the current input terminal in real time.

[0035] (3) Judgment: The control processing unit judges whether Γ is lower than the preset threshold (e.g., 0.1, i.e., SWR<1.22). If it is lower, the current state is maintained; if it is higher, the matching procedure is started.

[0036] (4) Calculation and execution: The control processing unit calculates the latest capacitor array combination required to minimize Γ (i.e. which RF switches should be closed) according to the built-in algorithm, and sends the control word to the RF switches through the drive circuit to change the network structure.

[0037] (5) Verification and iteration: After the circuit stabilizes (microseconds to milliseconds), measure Γ again. If it still does not match, perform fine-tuning iterations until it matches successfully.

[0038] (6) Monitoring: After a successful match, the system enters the monitoring mode and monitors Γ periodically or continuously. If the mismatch exceeds the threshold due to load changes, the above matching process will be retried.

[0039] In an optional embodiment, the programmable automatic impedance matching system further includes a protection circuit electrically connected to the control processing unit for overcurrent, overvoltage, and overtemperature protection to prevent damage to the system in case of load open circuit, short circuit, or arcing.

[0040] In summary, compared with the prior art, this utility model has at least the following advantages: The programmable automatic impedance matching system provided by this utility model includes a VI detector, a control processing unit, and a matching network. The control processing unit can automatically adjust the network topology of the matching network according to the real-time signal output by the VI detector, thereby achieving automated impedance control and effectively improving the efficiency, stability, and process consistency of high-RF energy applications.

[0041] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.

Claims

1. A programmable automatic impedance matching system, characterized in that, Includes a VI detector, a control and processing unit, and a matching network; The VI detector is used to acquire the impedance value and reflection coefficient value of the input terminal of the matching network in real time, and output the acquired information to the control processing unit in real time. The matching network includes a fixed inductor and two capacitor arrays connected to the input and output terminals of the fixed inductor respectively; the capacitor arrays include multiple capacitors with different capacitance values, the multiple capacitors are connected in parallel, and an RF switch is connected in series on each branch of the capacitor. The control processing unit stores the correspondence between impedance values ​​and network topology, and is used to control the on / off state of relevant radio frequency switches according to the correspondence and the information output in real time by the VI detector to adjust the network topology of the matching network.

2. The programmable automatic impedance matching system as described in claim 1, characterized in that, The control processing unit includes a core controller and a drive circuit; The core controller is used to generate a control signal to adjust the current network topology to the target network topology corresponding to the current impedance value when the reflection coefficient value output by the current VI detector exceeds the threshold. The drive circuit is used to convert the control signal generated by the core controller into a drive signal to control the operation of the radio frequency switch.

3. The programmable automatic impedance matching system as described in claim 1, characterized in that, The VI detector includes a voltage coupler, a current sensor, and an amplitude and phase detection chip; The voltage coupler is used to sample radio frequency voltage signals; The current sensor is used to sample radio frequency current signals; The amplitude and phase detection chip is used to convert voltage and current signals into in-phase DC component voltage and quadrature DC component voltage.

4. The programmable automatic impedance matching system as described in claim 3, characterized in that, The current sensor uses a Rogowski coil.

5. The programmable automatic impedance matching system as described in claim 1, characterized in that, The capacitance of the capacitor array is designed with binary weighting for the capacitance of its multiple capacitors.

6. The programmable automatic impedance matching system as described in claim 1, characterized in that, The radio frequency switch employs one of the following: a high-speed PIN diode, a MEMS radio frequency switch, and a high-voltage GaN FET.

7. The programmable automatic impedance matching system as described in claim 1, characterized in that, It also includes a protection circuit, which is electrically connected to the control processing unit and is used to implement overcurrent, overvoltage and overtemperature protection.

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