A variable vacuum capacitor

Abstract

This utility model discloses a variable vacuum capacitor, comprising: a driving unit, a capacitance measuring unit, and a protection unit; the measuring end of the capacitance measuring unit is connected to the electrodes of the capacitor element of the variable vacuum capacitor, and the capacitance measuring unit is used to measure the capacitance value of the capacitor element; the driving unit is connected to the capacitance measuring unit, and the driving unit is configured to generate a driving signal based on the capacitance value, the driving signal being used to control the movement of the actuator of the variable vacuum capacitor, thereby adjusting the capacitance value of the capacitor; the protection unit is connected in series in the signal transmission circuit of the capacitance measuring unit, and the protection unit is used to connect or disconnect the signal transmission circuit.

Description

Technical Field

[0001] This utility model relates to the field of capacitor technology, and in particular to a variable vacuum capacitor. Background Technology

[0002] Vacuum capacitors can automatically and accurately adjust their capacitance value according to actual needs, enabling semiconductor devices to reach a tuned state.

[0003] In actual production and use, it was found that the manufacturing process of this type of product could not overcome the technical bottleneck. The machining accuracy of the parts is at the micron level, which is the limit. As a result, the current domestic variable vacuum capacitor products are generally characterized by unstable mechanical structure. They are affected by gravity, vibration, and uneven force applied by the internal parts themselves, which makes the capacitance value easy to change at a fixed position point, and the change is random.

[0004] Based on the foregoing, the actual capacitance adjustment process is determined solely by the accuracy achievable by the motor control system itself, which limits the adjustment accuracy of the variable vacuum capacitor to 1%. This level of accuracy cannot meet the requirements for stable wafer fabrication on high-end semiconductor lithography equipment. Utility Model Content

[0005] This invention provides a variable vacuum capacitor to improve the capacitance adjustment accuracy of the variable vacuum capacitor.

[0006] This utility model embodiment provides a variable vacuum capacitor, including: a driving unit, a capacitance measuring unit, and a protection unit;

[0007] The measuring end of the capacitance measuring unit is connected to the electrodes of the capacitor element of the variable vacuum capacitor, and the capacitance measuring unit is used to measure the capacitance value of the capacitor element.

[0008] The drive unit is connected to the capacitance measurement unit. The drive unit is configured to generate a drive signal based on the capacitance value. The drive signal is used to control the movement of the actuator of the variable vacuum capacitor, thereby adjusting the capacitance value of the capacitor.

[0009] The protection unit is connected in series in the signal transmission circuit of the capacitance measurement unit, and the protection unit is used to connect or disconnect the signal transmission circuit.

[0010] Optionally, the drive unit is configured to generate a feedback control signal using a target capacitance value and the capacitance value, the feedback control signal serving as the drive signal.

[0011] Optionally, the capacitance measurement unit includes an LCR digital bridge.

[0012] Optionally, the LCR digital bridge is equipped with a metal shielded housing.

[0013] Optionally, the LCR digital bridge includes at least an AC power supply unit, a current sensing unit, and a voltage sensing unit.

[0014] The AC power supply unit and the current sensing unit are connected in series. The AC power supply unit is used to inject an AC signal into the capacitor, and the current sensing unit is used to measure the current passing through the capacitor.

[0015] The voltage sensing unit is connected in parallel with the capacitor, and the voltage sensing unit is used to measure the voltage of the capacitor.

[0016] Optionally, the actuator may include a motor.

[0017] Optionally, the drive unit controls the adjustment accuracy of the actuator to be ±0.01pF to ±0.1pF.

[0018] Optionally, the protection unit includes an isolating switch, which is connected in series in the signal transmission loop between the measuring terminal of the capacitance measuring unit and the signal input terminal of the capacitance measuring unit.

[0019] Optionally, the disconnecting switch includes an electromagnetic relay, the on / off state of which controls the connection or disconnection of the signal transmission circuit.

[0020] Optionally, the protection unit further includes an electromagnetic switch, which is connected in series in the signal transmission loop between the signal output terminal of the capacitance measurement unit and the signal input terminal of the drive unit.

[0021] Compared with existing technologies, the advantages of this invention are as follows: This invention proposes a variable vacuum capacitor equipped with a capacitance measurement unit and a protection unit. The capacitance measurement unit can acquire the current capacitance value of the capacitor in real time, and the drive unit can control the precise operation of the actuator based on the measured capacitance value, thereby rapidly bringing the actual capacitance value close to the target value and ultimately meeting the capacitance adjustment accuracy requirements of the capacitor. The protection unit is connected in series in the signal transmission circuit, constructing a safety barrier without affecting the adjustment accuracy. The protection unit prevents high-voltage signals from damaging the sensitive elements of the capacitance measurement unit or the control circuit of the drive unit during the operation of the variable vacuum capacitor, reducing the risk of equipment damage. Attached Figure Description

[0022] Figure 1 This is a block diagram of the variable vacuum capacitor structure in the embodiment;

[0023] Figure 2This is a schematic diagram of the LCR digital bridge in the embodiment;

[0024] Figure 3 This is a schematic diagram of the variable vacuum capacitor structure in the embodiment. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0026] Figure 1 This is a block diagram of the variable vacuum capacitor structure in the embodiment, for reference. Figure 1 The variable vacuum capacitor includes a drive unit 100, a capacitance measurement unit 200, and a protection unit 300.

[0027] The measuring end of the capacitance measuring unit 200 is connected to the electrode of the capacitor element 1 of the variable vacuum capacitor, and the capacitance measuring unit 200 is used to measure the capacitance value of the capacitor element 1.

[0028] The drive unit 100 is connected to the capacitance measurement unit 200. The drive unit 100 is configured to generate a drive signal based on the capacitance value. The drive signal is used to control the movement of the actuator 2 of the variable vacuum capacitor, thereby adjusting the capacitance value of the capacitor 1.

[0029] The protection unit 300 is connected in series in the signal transmission circuit of the capacitance measurement unit 200. The protection unit 300 is used to connect or disconnect the signal transmission circuit.

[0030] In this scheme, the drive unit 100 is the core control component for dynamically adjusting the capacitance value in the variable vacuum capacitor. Its function is to generate and output the drive signal of the actuator 2, control the action of the actuator 2, and ultimately achieve precise adjustment of the capacitance value of the capacitor 1.

[0031] In this solution, the drive unit 100 may include a control module, which may be a microprocessor (MCU). The control module has a preset control algorithm, which generates and outputs drive signals.

[0032] The drive unit 100 may also include a drive circuit, which converts the drive signal into the current and voltage signals required for the operation of the actuator 2, so as to meet the power requirements of the actuator 2.

[0033] The drive unit 100 can also be configured with a feedback interface, which is used to receive feedback signals from the capacitance measurement unit 200. The feedback signals can be used to assist in determining whether the capacitance value of the capacitor 1 has been adjusted to the correct value.

[0034] In this scheme, the actuator 2 directly participates in the adjustment of the capacitance value of the capacitor 1. Its function is to change the electrode structure of the capacitor 1 (such as electrode spacing, relative area or overlap) through physical movement, thereby realizing the dynamic adjustment of the capacitance value.

[0035] For example, in this solution, the form of the actuator 2 can be selected according to design requirements. For example, the actuator 2 can be an electromagnetic drive actuator, a piezoelectric drive actuator, a motor drive actuator, a bellows drive actuator, etc.

[0036] In this scheme, the capacitor 1 includes at least two oppositely arranged electrodes (such as a fixed electrode and a moving electrode). The fixed electrode is fixed in position, and the moving electrode can be displaced (such as translation, rotation or extension) by the drive of the actuator 2, thereby changing the facing area, spacing or shape between the electrodes.

[0037] The electrodes of capacitor 1 are sealed inside a vacuum housing. The vacuum housing or the housing itself may be provided with a support and insulation structure for fixing the stationary electrode and guiding the movement of the moving electrode.

[0038] This solution does not limit the main structure of the variable vacuum capacitor; for example, its main structure can be the same as that described in CN222338084U. The connection method and working principle of the variable vacuum capacitor main body are not described in detail in this solution.

[0039] In this scheme, the capacitance measurement unit 200 is used to measure the capacitance value of the capacitor 1. The measuring terminals of the capacitance measurement unit 200 need to be connected to the two electrodes (fixed plate and moving plate) of the capacitor 1 respectively to form a closed measurement circuit. Through this measurement circuit, the capacitance measurement unit 200 can acquire specific signals and then calculate the real-time capacitance value.

[0040] For example, in this solution, the electrode signal can be led from the electrode to the capacitance measurement unit 200 through a vacuum-sealed lead (such as a glass-metal sealed lead). The vacuum-sealed lead is connected to the measurement terminal of the capacitance measurement unit 200 to avoid vacuum leakage and ensure stable signal transmission.

[0041] For example, in this solution, the specific structure and measurement principle of the capacitance measurement unit 200 are not limited. As one possible implementation, the capacitance measurement unit 200 may include a charging and discharging module, a reference power supply module, a sampling module, an ADC sampling module, and a data processing unit.

[0042] The charge / discharge module may include a high-speed switching device using a MOSFET. The input terminal of the module is connected to a reference power supply, the output terminal is connected to the electrode of capacitor 1, and the control terminal is connected to a data processing unit. The charge / discharge module is used for controlled switching of the charge / discharge device to achieve charge / discharge cycles for the capacitor.

[0043] The reference power supply module may include a voltage regulator chip. The reference power supply module is used to provide a stable reference power supply with known values. The output terminal of the reference power supply module is connected to the input terminal of the charge / discharge module.

[0044] The sampling module may include a sampling circuit, which is connected in series in the charging and discharging circuit. The module is used to convert the charging and discharging current into a sampleable voltage signal.

[0045] An ADC sampling module may include an ADC sampling chip. The input terminal of the ADC sampling module is connected to the sampling module, and the output terminal is connected to the data processing unit. The ADC sampling module is used to convert the voltage signal output by the sampling module into a digital signal.

[0046] The data processing unit may include an MCU. The data processing unit is used to control the charging and discharging timing of the charging and discharging module, receive the digital signal from the ADC sampling module, and calculate the capacitance value of capacitor 1 based on the digital signal.

[0047] For example, in this solution, the capacitance value is calculated using the sampling data during the charging phase, and the discharge phase is used to discharge the capacitor until the voltage across its terminals is 0V, which serves as a measurement reset for the next capacitance value calculation.

[0048] For example, in this solution, the data processing unit can be configured to calculate the capacitance value using the following formula:

[0049]

[0050] In the formula, C x U represents the capacitance value. ref i(t) represents the voltage value of the reference power supply output by the reference power supply module, and i(t) represents the sampled value of the charging current.

[0051] For example, in this solution, the driving unit 100 can directly read the capacitance value calculated by the data processing unit, or it can be configured to calculate the capacitance value in the same way as the data processing unit.

[0052] For example, depending on the design requirements, the structure of the capacitance measurement unit 200 can also be an LCR bridge structure, a resonant tracking measurement structure, etc.

[0053] In this scheme, the variable vacuum capacitor operates in a high-frequency, high-voltage environment, and the tuning process (adjusting the capacitance value of capacitor 1) is completed before the high-frequency, high-voltage current passes through. The main purpose of setting up the protection unit 300 is:

[0054] To prevent high-voltage, high-frequency electrical signals from damaging the capacitance measurement unit 200, drive unit 100, etc., during normal operation of the variable vacuum capacitor.

[0055] For example, in this solution, the protection unit 300 meets the requirements of high voltage resistance, fast response, and high insulation resistance. The protection unit 300 may include relays, MOS devices, IGBT devices, etc. When the protection unit 300 is turned on, the measurement circuit is connected, and the capacitance value can be measured. When it is turned off, the measurement circuit is disconnected, and the high voltage signal is isolated.

[0056] In this scheme, the drive unit 100 is configured to generate drive signals based on the capacitance value, which can be achieved by using methods such as PID closed-loop control or fuzzy control to generate drive signals.

[0057] This embodiment proposes a variable vacuum capacitor, which is equipped with a capacitance measurement unit and a protection unit. The capacitance measurement unit can acquire the current capacitance value of the capacitor in real time. The drive unit can control the precise operation of the actuator based on the measured capacitance value, thereby rapidly bringing the actual capacitance value close to the target value and ultimately meeting the capacitance adjustment accuracy requirements of the capacitor. The protection unit is connected in series in the signal transmission circuit, constructing a safety barrier without affecting the adjustment accuracy. The protection unit prevents high-voltage signals from damaging the sensitive elements of the capacitance measurement unit or the control circuit of the drive unit during the operation of the variable vacuum capacitor, reducing the risk of equipment damage.

[0058] Based on any of the aforementioned schemes, in one possible implementation, the drive unit is configured to generate a feedback control signal using the target capacitance value and the capacitance value, and the feedback control signal serves as the drive signal.

[0059] For example, in this solution, the drive unit is configured based on closed-loop control theory. By comparing the deviation between the target capacitance value and the measured capacitance value, a drive signal is dynamically generated. The actuator (such as a motor) is adjusted by the drive signal to make the actual capacitance value approach the target value.

[0060] For example, in this solution, the drive unit can be configured with a touchscreen, and relevant personnel can manually set the target capacitance value through the GUI configured on the touchscreen. For instance, the target capacitance value can be set to 150pF through the GUI. If the drive unit calculates the current capacitance value to be 145pF, it generates a drive signal through a closed-loop control algorithm to control the motor to rotate a specified number of steps (e.g., 12 steps) to bring the capacitance value close to the target capacitance value.

[0061] For example, in this solution, the driving unit can also be configured with a communication interface (such as UART, SPI, I2C, etc.). The driving unit can be connected to a host computer or RF power supply through the communication interface, and receive the target capacitance value sent to the driving unit through the communication interface.

[0062] For example, in this solution, according to actual needs, the driver unit can pre-store an impedance matching table, which is used to determine the target capacitance value at a specified frequency. For instance, the RF power supply sends a frequency switching command to the driver unit, and the driver unit calls the impedance matching table to determine the target capacitance value (e.g., 200pF) corresponding to the switching frequency. The driver unit generates a drive signal through a closed-loop control algorithm to make the capacitance value close to the target capacitance value. After adjustment, the driver unit sends a confirmation signal to the RF power supply.

[0063] Based on any of the aforementioned schemes, in one possible implementation, the capacitance measurement unit includes an LCR digital bridge.

[0064] For example, in this solution, the LCR digital bridge can be based on the balanced bridge method, by adjusting the known parameters to make the bridge circuit balanced, and then the parameters of the capacitor under test can be deduced based on the balance conditions.

[0065] For example, in this solution, the LCR digital bridge may include a high-frequency signal source and a measurement bridge circuit. The high-frequency signal source is used to generate a frequency-stable, amplitude-adjustable high-frequency sinusoidal signal as the excitation signal for the measurement bridge circuit. The measurement bridge circuit consists of four arms, one of which is connected to the capacitor under test, and the other three arms are configured with standard components with known parameters.

[0066] Using the bridge balance condition, when the impedances of the four arms of the bridge satisfy the condition that the products of the impedances of the opposite arms are equal (Z1·Z3=Z2·Z4), the unbalanced signal output by the bridge is zero. At this time, the capacitance value of the capacitor under test can be derived from the known parameters of the arms. The calculation formula is as follows:

[0067]

[0068] In the formula, C x Indicates the capacitor being tested, C s R1 and R2 are the capacitors and resistors with known parameters configured for the other three bridge arms, respectively.

[0069] In this solution, the LCR digital bridge features high precision, wide applicability, and strong anti-interference capability, which can meet the needs of precision testing.

[0070] Based on any of the aforementioned solutions, in one possible implementation, the LCR digital bridge is configured with a metal shielding housing.

[0071] In this design, the metal shielding shell can be made of a metal material with good electrical conductivity (such as aluminum alloy). The metal shielding shell utilizes the reflection, absorption, and guidance properties of metal to block external electromagnetic interference from entering the bridge, while preventing high-frequency signals (such as test signals above 1MHz) inside the LCR digital bridge from leaking out and interfering with other equipment, ensuring that high-precision measurements are not affected by the electromagnetic environment.

[0072] Figure 2 This is a schematic diagram of the LCR digital bridge in the embodiment, for reference. Figure 2 Based on any of the aforementioned schemes, in one possible implementation scheme, the LCR digital bridge includes at least an AC power supply unit 201, a current sensing unit 202, and a voltage sensing unit 203.

[0073] The AC power supply unit 201 and the current sensing unit 202 are connected in series. The AC power supply unit 201 is used to inject AC signals into the capacitor, and the current sensing unit 202 is used to measure the current passing through the capacitor.

[0074] The voltage sensing unit 203 is connected in parallel with the capacitor and is used to measure the voltage of the capacitor.

[0075] In this scheme, the LCR digital bridge adopts a four-wire LCR digital bridge, which has a current path and a voltage measurement path, and can realize high-precision measurement of capacitance value.

[0076] In this scheme, the AC power supply unit is a high-frequency signal source. The AC power supply unit may include a DDS signal generator and a constant current conversion circuit. The DDS signal generator is used to generate a high-precision sine wave, and the constant current conversion circuit is used to convert the voltage signal output by the DDS signal generator into a constant current output (alternating current).

[0077] For example, in this solution, the capacitance value can be calculated using the following formula:

[0078]

[0079] In the formula, C x I represents the capacitance value of the capacitor under test, V represents the current measurement value, ω represents the voltage measurement value, and ω represents the angular frequency of the AC signal.

[0080] For example, in this solution, Kelvin clips can be used to connect the LCR digital bridge to the capacitor, wherein the wires for setting the voltage path are physically isolated from the wires for setting the current path.

[0081] For example, in this solution, the LCR digital bridge can also be configured with a communication interface, which allows the LCR digital bridge to communicate with the drive unit.

[0082] In this solution, a four-wire LCR digital bridge is used to measure the capacitance value. It is less susceptible to interference and has less measurement loss in high-frequency scenarios, which can improve the measurement accuracy.

[0083] Based on any of the aforementioned solutions, in one possible implementation, the actuator includes a motor.

[0084] In this scheme, the motor acts as the actuator, and the mechanical transmission mechanism converts the rotational motion of the motor into the position of the moving electrode of the capacitor, ultimately achieving precise adjustment of the capacitance value.

[0085] In this solution, the type of motor can be selected based on the control precision required by the capacitor value. For scenarios with medium precision requirements (±0.1pF), a stepper motor can be used. For scenarios with high precision requirements (±0.01pF), a servo motor can be used.

[0086] Based on any of the aforementioned schemes, in one possible implementation scheme, the adjustment accuracy of the drive unit controlling the actuator is ±0.1pF.

[0087] In this design, the actuator can be a stepper motor that meets the accuracy requirements, and the mechanical transmission mechanism can be a ball screw. The control module in the drive unit can be an STM32 microcontroller. The drive circuit uses a driver specifically designed for the selected stepper motor. The capacitance measurement unit uses a high-precision LCR bridge.

[0088] In this solution, an STM32 microcontroller is configured to generate the drive signal for the stepper motor using PID closed-loop control. Based on closed-loop control and hardware devices that meet accuracy requirements, the capacitor value is adjusted with an accuracy of ±0.1pF.

[0089] Based on any of the aforementioned solutions, in one possible implementation, the protection unit includes a disconnect switch, which is connected in series in the signal transmission loop between the measuring terminal of the capacitance measuring unit and the signal input terminal of the capacitance measuring unit.

[0090] In this solution, to prevent the high voltage and high frequency signals of the variable vacuum capacitor from damaging the capacitance measurement unit through the measurement circuit, the isolating switch can cut off the signal transmission path of the measurement circuit when the variable vacuum capacitor is working, so as to realize that the measurement circuit is conducting when the capacitance value is measured and is isolated (capacitance measurement unit) when the variable vacuum capacitor is working.

[0091] For example, in this solution, the disconnecting switch can be set at any position between the measuring end of the capacitance measuring unit and the signal input end of the capacitance measuring unit. For instance, the first connection end of the disconnecting switch can be connected to the measuring end, and the second connection end can be connected to the signal input end of the capacitance measuring unit.

[0092] For example, in this solution, the disconnect switch can be configured to be controlled by a level signal to close or open. For instance, the MCU in the driver unit can be configured to connect to the control terminal of the disconnect switch via a GPIO interface. When the disconnect switch needs to be closed, the MCU is configured to output a high level; when the disconnect switch needs to be opened, the MCU is configured to output a low level.

[0093] Based on any of the aforementioned schemes, in one possible implementation, the disconnecting switch includes an electromagnetic relay, the on / off state of which is used to control the connection or disconnection of the signal transmission circuit.

[0094] In this scheme, the electromagnetic relay drives the mechanical contacts to open and close through electromagnetic force, thereby realizing the on / off control of the signal transmission circuit.

[0095] For example, in this solution, the stationary contact of the electromagnetic relay can be connected in series in the signal transmission circuit. When the coil of the electromagnetic relay is energized, the electromagnetic force attracts the moving contact and the stationary contact, and the signal transmission circuit is connected (allowing the capacitance measurement signal to pass through); when the coil is de-energized, the spring force separates the contacts, and the circuit is broken (blocking high voltage / high frequency signals).

[0096] For example, in this solution, if the MCU in the drive unit is used to control the energization or de-energization of the electromagnetic relay coil, electrical isolation can be provided between the MCU and the electromagnetic relay to prevent signals from interfering with the MCU through the control link. For instance, the MCU can be connected to the electromagnetic relay coil through an opto-isolator.

[0097] Based on any of the aforementioned solutions, in one possible implementation, the protection unit further includes an electromagnetic switch, which is connected in series in the signal transmission loop between the signal output terminal of the capacitance measurement unit and the signal input terminal of the drive unit.

[0098] In this scheme, an electromagnetic switch is connected in series between the signal output terminal of the capacitance measurement unit and the signal input terminal of the drive unit. The electromagnetic switch is used to realize secondary protection for the transmission of measurement signals. The electromagnetic switch is configured to close during the safe tuning stage and open during the high voltage operation stage, forming a double isolation protection system with the isolating switch set at the front end.

[0099] For example, in this solution, the electromagnetic switch can be an electromagnetic relay or a double-pole double-throw switch, and the control of the electromagnetic switch can be achieved by the MCU in the drive unit.

[0100] For example, in this solution, the MCU in the drive unit can be configured to control the front-end isolation switch to close first when tuning begins, and then control the electromagnetic switch to close after a certain delay (e.g., 10ms). The measurement signal from the capacitance measurement unit can be transmitted to the drive unit, and the drive unit adjusts the capacitor according to the measurement signal.

[0101] After tuning is complete, the MCU first controls the isolating switch to open, and then controls the electromagnetic switch to open, to prevent high-voltage and high-frequency electrical signals from causing breakdown and damage to the capacitance measurement unit and drive unit through the measurement lines.

[0102] Figure 3 This is a schematic diagram of the variable vacuum capacitor structure in the embodiment, for reference. Figure 3 Based on any of the aforementioned schemes, in one possible implementation scheme, the variable vacuum capacitor includes: a driving unit 100, a capacitance measuring unit 200, and a protection unit 300.

[0103] The measuring end of the capacitance measuring unit 200 is connected to the electrode of the capacitor element 1 of the variable vacuum capacitor, and the capacitance measuring unit 200 is used to measure the capacitance value of the capacitor element 1.

[0104] The drive unit 100 is connected to the capacitance measurement unit 200. The drive unit 100 is configured to generate a drive signal based on the capacitance value. The drive signal is used to control the movement of the actuator 2 of the variable vacuum capacitor, thereby adjusting the capacitance value of the capacitor 1.

[0105] The protection unit 300 is connected in series in the signal transmission circuit of the capacitance measurement unit 200. The protection unit 300 is used to connect or disconnect the signal transmission circuit.

[0106] In this scheme, the capacitance measurement unit 200 is set to use a (four-wire) LCR digital bridge, and the LCR digital bridge is equipped with a metal shielding shell.

[0107] In this scheme, the protection unit 300 includes an isolating switch, which is connected in series in the signal transmission loop between the measuring terminal of the capacitance measuring unit and the signal input terminal of the capacitance measuring unit.

[0108] In this scheme, an electromagnetic switch is also connected in series in the signal transmission circuit between the signal output terminal of the capacitance measurement unit 200 and the signal input terminal of the drive unit 100.

[0109] In this scheme, the variable vacuum capacitor is equipped with a capacitance measurement unit 200. The capacitance measurement unit 200 can measure the capacitance value of the capacitor 1 in real time. The capacitance measurement value can be transmitted to the drive unit 100. The drive unit 100 compares the capacitance measurement value with the target capacitance value. If there is an error between the actual capacitance value and the required capacitance value, the drive unit 100 will control the actuator 2 to move to make up for the capacitance error until the required capacitance value point is reached.

[0110] In the resonant cavity, the inductance, capacitance, and resonant frequency are all determined. If the resonant cavity needs to reach resonance, the capacitor needs to be adjusted to 150pF, but the actual capacitance value only reaches 148.5pF. If the RF power supply is directly powered on at this moment, the reflected power may be very high, and the entire circuit may heat up rapidly and be damaged.

[0111] In this scheme, after the capacitance value of capacitor 1 is adjusted to 148.5pF, the drive unit 100 quickly adjusts the actuator 2 (e.g., motor and screw) of the variable vacuum capacitor according to the capacitance deviation because the target capacitance value has not been reached.

[0112] The capacitance deviation is 1.5pF (150pF-148.5pF). The drive unit 100 continuously adjusts the actual capacitance to the range of 150pF±0.1pF through PID control.

[0113] In this scheme, the capacitance measurement unit 200 adopts a (four-wire) LCR digital bridge. The LCR digital bridge is configured to measure and output the capacitance value. The input line of the LCR digital bridge is 4-wire. Two lines are connected to the positive terminal of the capacitor, and the other two lines are connected to the negative terminal of the capacitor. At high frequencies, there is no difference between the positive and negative terminals.

[0114] In this scheme, the protection unit 300 adopts a (high voltage) disconnect switch. The disconnect switch is equipped with an electromagnetic relay. When the coil of the battery relay is energized, the disconnect switch is closed. When the coil is de-energized, the disconnect switch is open. The high voltage isolation function is achieved through the isolation.

[0115] In this scheme, after tuning is completed, the isolating switch is first opened to disconnect the circuit of the high-voltage side electrical signal of the capacitance measurement unit 200 and protect the capacitance measurement unit 200; in addition, the electromagnetic switch on the drive unit 100 side is also opened in a controlled manner to further protect the capacitance measurement unit 200 and the drive unit 100.

[0116] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A variable vacuum capacitor, characterized by, include: Drive unit, capacitance measurement unit, and protection unit; The measuring end of the capacitance measuring unit is connected to the electrodes of the capacitor element of the variable vacuum capacitor, and the capacitance measuring unit is used to measure the capacitance value of the capacitor element. The drive unit is connected to the capacitance measurement unit. The drive unit is configured to generate a drive signal based on the capacitance value. The drive signal is used to control the movement of the actuator of the variable vacuum capacitor, thereby adjusting the capacitance value of the capacitor. The protection unit is connected in series in the signal transmission circuit of the capacitance measurement unit, and the protection unit is used to connect or disconnect the signal transmission circuit.

2. The variable vacuum capacitor of claim 1, wherein The drive unit is configured to generate a feedback control signal using a target capacitance value and the capacitance value, the feedback control signal serving as the drive signal.

3. The variable vacuum capacitor of claim 1, wherein, The capacitance measurement unit includes an LCR digital bridge.

4. The variable vacuum capacitor of claim 3, wherein, The LCR digital bridge is equipped with a metal shielding housing.

5. The variable vacuum capacitor of claim 3, wherein, The LCR digital bridge includes at least an AC power supply unit, a current sensing unit, and a voltage sensing unit. The AC power supply unit and the current sensing unit are connected in series. The AC power supply unit is used to inject an AC signal into the capacitor, and the current sensing unit is used to measure the current passing through the capacitor. The voltage sensing unit is connected in parallel with the capacitor, and the voltage sensing unit is used to measure the voltage of the capacitor.

6. The variable vacuum capacitor of claim 1, wherein, The actuator includes a motor.

7. The variable vacuum capacitor of claim 1, wherein The drive unit controls the adjustment accuracy of the actuator to be ±0.01pF to ±0.1pF.

8. The variable vacuum capacitor of claim 1, wherein, The protection unit includes an isolating switch, which is connected in series in the signal transmission loop between the measuring terminal of the capacitance measuring unit and the signal input terminal of the capacitance measuring unit.

9. The variable vacuum capacitor as claimed in claim 8, characterized in that, The disconnecting switch includes an electromagnetic relay, and the switching on and off of the electromagnetic relay is used to control the connection or disconnection of the signal transmission circuit.

10. The variable vacuum capacitor of claim 1, wherein, The protection unit also includes an electromagnetic switch, which is connected in series in the signal transmission loop between the signal output terminal of the capacitance measurement unit and the signal input terminal of the drive unit.

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