A micro-energy intelligent aging device for vacuum gap

Abstract

The present invention discloses a micro-energy intelligent aging device for a vacuum gap, which includes a high-voltage power supply module, a voltage conditioning module, an energy control module, an aging progress evaluation module, and a central control module. The high-voltage power supply module outputs through the voltage conditioning module to the vacuum gap and the aging energy control module connected in parallel; the voltage conditioning module realizes the energy isolation between the high-voltage power supply and the vacuum gap, and the aging energy after the breakdown of the vacuum gap is only provided by the aging energy control module. At the same time, continuous voltage pulses are realized at both ends of the vacuum gap; the aging progress evaluation module collects breakdown information and transmits it to the central control module; the central control module evaluates the aging process according to the breakdown information and outputs control parameters to the high-voltage power supply module and the energy control module to intelligently adjust the aging voltage and the aging energy. This device can achieve precise control of energy from the mJ level to the J level, and can intelligently adjust the aging voltage and the aging energy according to the aging process, realizing higher aging efficiency and better aging effect.

Description

Technical Field

[0001] The present invention relates to the technical field of vacuum gap conditioning, and particularly to an intelligent micro-energy conditioning device for vacuum gaps, which can achieve adjustable conditioning energy from mJ to J during the conditioning process of vacuum gaps, monitor the conditioning status in real time, and comprehensively adjust the conditioning voltage and energy according to multiple parameters. Background Art

[0002] Improving the insulation performance of vacuum gaps is an urgent need in many fields, such as particle accelerators, traveling wave tubes, neutron sources, vacuum switches, etc. Conditioning is currently the most common measure to improve the insulation performance of vacuum gaps.

[0003] Aging generally refers to the process of removing insulation defects on the electrode surface through methods such as arc ablation, thereby improving the insulation ability of the gap. The electrode surface inevitably has undulations at the microscale. When a high voltage is applied between the electrodes, sharper micro-protrusions will generate a higher local electric field, which is prone to breakdown. The local electric field enhancement degree is generally described by the field enhancement coefficient β. Okubo et al. (H. Okubo, T. Yasuoka, et al. “Electrode conditioning mechanism based on pre-breakdown current under non-uniform electric field in vacuum,” in 2008 23rd International Symposium on Discharges and Electrical Insulation in Vacuum, Sep. 2008.) found that aging mainly realizes the increase of the breakdown voltage by arc ablation of local micro-protrusions, passivating or removing them, and reducing the breakdown field enhancement coefficient β. However, the change of the contact surface morphology by arc ablation has a large randomness, which has a great relationship with the arc energy. A larger arc energy may generate new defects while removing the original defects. For example, Kondo et al. (F. Kondo, H. Kojima, et al. “Suppression of Conditioning Effect in Vacuum by Micro-protrusions from Anode,” in 2019 5th International Conference on Electric Power Equipment-Switching Technology (ICEPE-ST), Oct. 2019, pp. 467–471.) found that the ablation by a larger arc energy may cause particles to fly out from the anode and attach to the cathode to form larger micro-protrusions, which restricts the aging effect.Kojima et al. (H. Kojima, T. Takahashi, et al. “Dependence of spark conditioning on breakdown charge and electrode material under a non-uniform electric field in vacuum,” IEEE Transactions on Dielectrics and Electrical Insulation, vol. 23, no. 5, pp. 3224–3230, Oct. 2016.) studied the influence of conditioning discharge amount on the saturated breakdown electric field strength by adding a current-limiting resistor, and found that in many cases, the smaller the discharge amount, the higher the saturated breakdown electric field strength, but the more times are required for conditioning to reach saturation. That is to say, the lower the conditioning energy, the better the conditioning effect, but the lower the conditioning efficiency. The literature also mentions that a vacuum gap generally requires thousands of times of conditioning to achieve an ideal effect. Therefore, the conditioning efficiency is also a key factor to be considered when designing a conditioning device.

[0004] Traditional conditioning methods mainly include current conditioning and voltage conditioning, with energies generally in the KJ - MJ range, and the discharge energy is too large and uncontrollable. Patent (Application No. CN98112973.0) uses high-frequency current for conditioning, but there is still the problem of excessive and uncontrollable discharge energy. Patent (Application No. CN202110972202.2) proposes to adjust the discharge energy according to the voltage value of each breakdown during the conditioning using a standard lightning impulse voltage, and a certain degree of control over the conditioning energy can be achieved within the kJ range; however, on the one hand, according to the aforementioned literature, using only the breakdown voltage as the basis for adjusting the conditioning energy is not sufficient; on the other hand, each output of a lightning impulse voltage only achieves one-time conditioning, and the typical charging time of a lightning impulse voltage generator is 30 s - 1 min. Considering that the typical number of conditioning times for a vacuum gap is more than 1000 times, the conditioning time for each gap is about 10 h, and the conditioning efficiency is low. Patent (Application No. CN 102426954A) uses continuous nanosecond pulses for conditioning, reducing the discharge energy to the J range, and at the same time, the typical pulse frequency is 1000 times / s, greatly improving the conditioning efficiency; however, this conditioning method needs to preset conditioning parameters such as voltage, gap distance, and energy before the start of conditioning, and cannot dynamically adjust according to the current conditioning process. Patent (Application No. CN106872888A) further uses the method of DC superimposed pulses, reducing the requirement for the withstand voltage capacity of the device, but there is also the problem of being unable to dynamically adjust the conditioning energy during the conditioning process. Summary of the Invention

[0005] The object of the present invention is to overcome the above-mentioned drawbacks of the prior art, and to provide a micro-energy intelligent aging device for a vacuum gap, which can achieve mJ-level aging energy during the aging process of the vacuum gap, monitor the aging status in real time, and comprehensively adjust the aging energy according to multiple parameters. Through the insulation state detection and aging process evaluation carried out in real time during the aging process, the aging voltage and aging energy are intelligently adjusted, while ensuring the best aging effect of the vacuum gap, and taking into account the aging efficiency.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A micro-energy intelligent aging device for a vacuum gap, comprising a high-voltage power supply module 1, a voltage conditioning module 2, an energy control module 3, an aging progress evaluation module 4, and a central control module 5;

[0008] The high-voltage power supply module 1 generates a high voltage under the command of the central control module 5, and after passing through the voltage conditioning module 2, outputs to both ends of the directly parallel vacuum gap 6 and energy control module 3; the vacuum gap 6 breaks down under the high voltage, and the aging energy after breakdown is provided by the energy control module 3; the aging progress evaluation module 4 collects breakdown information and analyzes breakdown characteristics, and transmits the results to the central control module 5; the central control module 5 feeds back control signals to the energy control module 3 and the high-voltage power supply module 1 according to the breakdown information and the aging energy control strategy, so as to realize the intelligent adjustment of the aging voltage and aging energy;

[0009] The aging energy control strategy includes the following steps:

[0010] 1) Set the aging energy to the maximum value Q max ;

[0011] 2) Gradually increase the output voltage of the high-voltage power supply module 1 at a speed of 1 kV / s until the first breakdown occurs, record the breakdown information, and stop boosting at the same time;

[0012] 3) Keep the output voltage of the high-voltage power supply module 1 unchanged and continue aging at this voltage value; if no breakdown occurs continuously for 1 min at this voltage value, it is considered that the aging is completed at this voltage;

[0013] 4) Increase the output voltage of the high-voltage power supply module 1 by ΔU = 1 kV to U n+1 , and repeat step 3);

[0014] 5) If the aging is still not completed within 5 min after boosting to U n+1 , then retrieve the breakdown field enhancement coefficient β before each breakdown within 5 min, and perform linear fitting with the number of breakdowns as the abscissa and the β value as the ordinate. If the slope of the fitting result is less than -0.1, then maintain the voltage at U n+1 , and repeat step 5); otherwise, execute step 6);

[0015] 6) Reduce the aging energy by 0.2*(Q max -Q min ), where Q min is the minimum aging energy that the energy control module 3 can output; if the reduced aging energy is greater than or equal to Q min , then keep the output voltage unchanged and jump to step 3); otherwise, the aging ends.

[0016] During the aging process, the aging energy is dynamically adjusted in the order of mJ to J.

[0017] The voltage across the vacuum gap 6 drops to zero at breakdown, and then quickly recovers to the voltage value before breakdown, forming continuous pulses.

[0018] The high-voltage power supply module 1 is a power frequency voltage source or a DC voltage source.

[0019] The voltage conditioning module 2 includes a buffer capacitor 7 and an isolation resistor 8; the buffer capacitor 7 is a high-voltage pulse capacitor directly connected in parallel across the high-voltage power supply module 1, with filtering and energy storage functions; its capacitance value should ensure that after the vacuum gap 6 breaks down, the distortion amplitude of the output voltage of the high-voltage power supply module 1 does not exceed 10%; the isolation resistor 8 is a non-inductive high-voltage resistor connected between the buffer capacitor 7 and the high-voltage terminal of the vacuum gap 6; its resistance value should ensure that after the vacuum gap 6 breaks down, the current flowing from the high-voltage power supply module 1 and the buffer capacitor 7 through the isolation resistor 8 into the broken-down vacuum gap 6 is lower than the self-intercept current value of the vacuum gap 6 itself.

[0020] The energy control module 3 includes a variable vacuum capacitor bank 9 and a rotary stepping motor 10; the variable vacuum capacitor bank 9 is a plurality of high-voltage vacuum variable ceramic capacitors connected in series and parallel, directly connected in parallel across the vacuum gap 6; the voltage resistance of the energy control module 3 is increased by the series connection of a plurality of high-voltage vacuum variable ceramic capacitors; the maximum aging energy that the energy control module 3 can provide is increased by the parallel connection of a plurality of high-voltage vacuum variable ceramic capacitors; the rotary stepping motor 10 receives the control signal of the central control module 5, and its output terminal is connected to the control terminal of the variable vacuum capacitor bank 9, and the capacitance value is changed by rotating the control terminal of the variable vacuum capacitor bank 9, so as to realize the adjustment of the aging energy.

[0021] The aging progress evaluation module 4 includes a breakdown voltage measurement part 11, a field emission current measurement part 12, and a data preprocessing part 13.

[0022] The voltage measurement section 11 and the field emission current measurement section 12 roll to read the voltage and field emission current information at both ends of the vacuum gap 6; when the data preprocessing section 13 detects breakdown, it intercepts the voltage and field emission current data within a period of time before breakdown, extracts the breakdown voltage and critical field emission current data, and further calculates the field enhancement factor β, effective emission area, and critical current density data before breakdown according to the Fowler-Noreheim formula, and transmits the results to the central control module 5.

[0023] The central control module 5 controls the on / off of the high-voltage power supply module 1 and adjusts its output voltage, receives and stores the breakdown information transmitted by the data preprocessing section 13 of the aging progress evaluation module 4, and based on the carried aging energy control strategy, outputs control signals to the high-voltage power supply module 1 and the rotary stepper motor 10 of the energy control module 3 in real time to achieve intelligent adjustment of the aging voltage and aging energy.

[0024] The central control module 5 opens a debugging interface to facilitate users to edit the aging energy control strategy according to the actual situation.

[0025] The beneficial effects of the present invention are as follows:

[0026] (1) The minimum aging energy of the present invention is in the mJ order of magnitude, and the aging energy can be automatically adjusted in the range of mJ to J order of magnitude through the energy control module, which can achieve a higher aging saturation voltage while taking into account the aging efficiency.

[0027] (2) The present invention realizes continuous voltage pulses through the voltage conditioning module, and the aging efficiency is significantly improved compared with traditional voltage aging.

[0028] (3) The aging progress evaluation module of the present invention can provide various parameters such as breakdown voltage, critical field emission current, field enhancement factor β, effective emission area, and critical current density for evaluating the aging effect according to the breakdown information of the vacuum gap, and provides an open interface in the central control module to facilitate users to write their own aging energy control strategies, which helps users set the required aging energy control strategies according to their own situations. Description of the Drawings

[0029] Figure 1 It is a schematic diagram of a micro-energy intelligent aging device for a vacuum gap;

[0030] Figure 2 It is a typical voltage and field emission current waveform diagram during the aging process;

[0031] Figure 3Variations of breakdown voltage, critical field emission current, field enhancement factor β, effective emission area, microscopic breakdown field strength, and critical current density with the number of aging cycles during the aging process. Specific implementation mode

[0032] The following further elaborates on an intelligent micro-energy aging device for a vacuum gap of the present invention in conjunction with the accompanying drawings and specific implementation modes.

[0033] The composition of an intelligent micro-energy aging device for a vacuum gap is as Figure 1 shown. It includes a high-voltage power supply module 1, a voltage conditioning module 2, an energy control module 3, an aging progress evaluation module 4, and a central control module 5. The output of the high-voltage power supply module 1 passes through the voltage conditioning module 2 and is output to both ends of the vacuum gap 6. The central control module 5 respectively receives the data transmitted by the aging progress evaluation module 4 and outputs control signals to the high-voltage power supply module 1 and the energy control module 3 according to the built-in aging energy control strategy.

[0034] The high-voltage power supply module 1 uses a power frequency voltage source, and the output voltage is controlled by the central control module 5. It passes through the voltage conditioning module 2 and is output to the vacuum gap 6 and the energy control module 3.

[0035] The voltage conditioning module 2 includes a buffer capacitor 7 and an isolation resistor 8: The buffer capacitor 7 is a high-voltage pulse coupling capacitor with a capacitance value of 10 nF; this capacitor is connected in parallel at both ends of the high-voltage power supply module 1 and has filtering and energy storage functions. The isolation resistor 8 is a glass enamel metal film high-frequency non-inductive high-voltage rod-shaped resistor with a resistance value of 100 kΩ; this resistor is connected at both ends of the buffer capacitor 7 and the vacuum gap 6, so that after the vacuum gap breaks down and arcs, the current provided by the buffer capacitor 7 and the high-voltage power supply module 1 to the vacuum gap 6 through the isolation resistor 8 is lower than the cut-off value of the vacuum gap, and the vacuum gap cannot maintain combustion and quickly extinguishes, realizing the energy isolation between the high-voltage power supply module 1 and the vacuum gap 6. After the vacuum arc extinguishes, the buffer capacitor 7 will charge the self-capacitance of the vacuum gap 6 through the isolation resistor 8, so that the voltage at both ends of the vacuum gap 6 returns to the value before breakdown, thus automatically realizing continuous voltage pulses. The typical waveform diagram of this voltage pulse and its corresponding field emission current is as Figure 2 shown. By magnifying and observing the part within the dashed box in the figure, it can be found that within one power frequency half-wave, there are multiple breakdown-recovery-charging-breakdown processes, realizing multiple aging; and the pulsed current after breakdown only flows through the vacuum gap and does not trigger the protection of the high-voltage power supply module 1, eliminating the need to restart the high-voltage power supply every time the vacuum gap breaks down, greatly improving the aging efficiency.

[0036] The energy control module 3 includes a variable vacuum capacitor bank 9 and a rotary stepper motor 10. The variable vacuum capacitor bank 9 includes four CKTB1200 / 35 / 300 variable vacuum capacitors, which are connected in two series and two parallel; this capacitor bank is connected in parallel across the vacuum gap 6 to provide the conditioning energy after the gap breakdown. The rotary stepper motor 10 is an 86 stepper motor equipped with a 750W servo, controlled by the central control module 5, and its output end is connected to the control end of the variable vacuum capacitor bank 9. By rotating the control end of the variable vacuum capacitor bank 9, the capacitance value of the capacitor bank is changed, thereby adjusting the conditioning energy.

[0037] The conditioning progress evaluation module 4 includes a voltage measurement part 11, a field emission current measurement part 12, and a data preprocessing part 13: The voltage measurement part 11 is a resistor-capacitor parallel divider and an output conditioning circuit. The field emission current measurement part 12 is a 1kΩ high-precision sampling resistor, a bidirectional transient suppression diode connected in parallel with it, and an output conditioning circuit. The data preprocessing part 13 mainly includes an ADS9266 high-speed ADC and an Xilinx Zynq-7010 high-performance FPGA. The high-speed ADC collects the analog signals provided by the voltage measurement part 11 and the field emission current measurement part 12 and converts them into digital signals to be provided to the FPGA. The FPGA is equipped with a breakdown detection program and a parameter extraction program. The breakdown detection program uses a sliding window wavelet algorithm to detect the occurrence of breakdown, and after the breakdown occurs, it transmits the voltage and field emission current data within 50μs before the breakdown to the parameter extraction program; the parameter extraction program directly obtains the breakdown voltage and the critical field emission current based on the voltage and field emission current data, and further calculates the field enhancement factor β, the effective emission area, the critical current density, etc. before the breakdown according to the Fowler-Nordheim formula, and transmits them to the central control module 5.

[0038] The central control module 5 is an STM32F103RGT6 single-chip microcomputer, which stores and receives the conditioning progress information transmitted by the conditioning progress evaluation module 4, determines the required applied voltage and conditioning energy according to the preset conditioning energy control strategy, and outputs control signals to the high-voltage power supply module 1 and the energy control module 3.

[0039] A conditioning energy control strategy can be:

[0040] 1) Set the conditioning energy to the maximum value Q max ;

[0041] 2) Gradually increase the output voltage of the high-voltage power supply module 1 at a speed of 1kV / s until the first breakdown occurs, record the breakdown information, and at the same time stop boosting;

[0042] 3) Keep the output voltage of the high-voltage power supply module 1 unchanged and conduct aging continuously at this voltage value; if there is no breakdown within 1 minute at this voltage value, it is considered that the aging at this voltage is completed;

[0043] 4) Increase the output voltage of the high-voltage power supply module 1 by ΔU = 1 kV to U n+1 and repeat step 3);

[0044] 5) If the aging is still not completed within 5 minutes after boosting the voltage to U n+1 , then retrieve the breakdown field enhancement coefficient β before each breakdown within 5 minutes, perform a linear fit with the number of breakdowns as the abscissa and the β value as the ordinate. If the slope of the fitting result is less than -0.1, keep the voltage at U n+1 and repeat step 5); otherwise, execute step 6);

[0045] 6) Reduce the aging energy by 0.2 * (Q max - Q min ), where Q min is the minimum aging energy that the energy control module 3 can output; if the reduced aging energy is greater than or equal to Q min , keep the output voltage unchanged and jump to step 3); otherwise, the aging ends.

[0046] The breakdown voltage U, the maximum field emission current Ie max , the field enhancement coefficient β, the effective emission area Ae, the microscopic breakdown electric field strength βU / d, and the critical current density Je max are as Figure 3 shown.

Claims

1. A micro-energy intelligent aging device for a vacuum gap, characterized in that, It includes a high-voltage power supply module (1), a voltage conditioning module (2), an energy control module (3), an aging progress evaluation module (4), and a central control module (5); The high-voltage power supply module (1) generates high voltage under the command of the central control module (5), and after passing through the voltage conditioning module (2), it is output to both ends of the directly parallel vacuum gap (6) and the energy control module (3); the vacuum gap (6) breaks down under high voltage, and the aging energy after breakdown is provided by the energy control module (3); the aging progress evaluation module (4) collects breakdown information and analyzes breakdown characteristics, and transmits the results to the central control module (5); the central control module (5) feeds back control signals to the energy control module (3) and the high-voltage power supply module (1) according to the breakdown information and the aging energy control strategy to achieve intelligent adjustment of the aging voltage and aging energy; The aging energy control strategy includes the following steps: 1) Set the burn-in energy to the maximum value Q max ; 2) Gradually increase the output voltage of the high-voltage power supply module (1) at a speed of 1 kV / s until the first breakdown occurs, record the breakdown information, and at the same time stop boosting; 3) Keep the output voltage of the high-voltage power supply module (1) unchanged and continue aging at this voltage value; If no breakdown occurs continuously for 1 minute at this voltage value, it is considered that the aging at this voltage is completed; 4) Increase the output voltage of the high-voltage power supply module (1) by ΔU = 1 kV to U n+1 , and repeat step 3); 5) If the voltage is boosted to U n+1 and the aging is still not completed within 5 minutes afterwards, then retrieve the breakdown field enhancement factor before each breakdown within 5 minutes β , use the number of breakdowns as the abscissa and β the value as the ordinate for linear fitting. If the slope of the fitting result is less than -0.1, then maintain the voltage at U n+1 , and repeat step 5); otherwise, execute step 6); 6) Reduce the burn-in energy by 0.2*(Q max -Q min ), where Q min is the minimum burn-in energy that the energy control module (3) can output; if the reduced burn-in energy is greater than or equal to Q min , then keep the output voltage unchanged and jump to step 3); otherwise, the burn-in ends; The aging progress evaluation module (4) includes a breakdown voltage measurement part (11), a field emission current measurement part (12), and a data preprocessing part (13); The voltage measurement section (11) and the field emission current measurement section (12) scroll and read the voltage and field emission current information at both ends of the vacuum gap (6); when the data preprocessing section (13) detects breakdown, it intercepts the voltage and field emission current data within a period of time before breakdown, extracts the breakdown voltage and critical field emission current data, and further calculates the field enhancement factor before breakdown according to the Fowler-Noreheim formula β , the effective emission area, and the critical current density data, and transmits the results to the central control module (5).

2. The micro-energy intelligent aging device for a vacuum gap according to claim 1, characterized in that: The aging energy is dynamically adjusted in the range of mJ to J during the aging process.

3. The micro-energy intelligent aging device for a vacuum gap according to claim 1, characterized in that: The voltage across the vacuum gap (6) drops to zero at the moment of breakdown, and then quickly recovers to the voltage value before breakdown, forming continuous pulses.

4. The micro-energy intelligent aging device for a vacuum gap according to claim 1, characterized in that: The high-voltage power supply module (1) is a power frequency voltage source or a DC voltage source.

5. The micro-energy intelligent aging device for a vacuum gap according to claim 1, characterized in that: The voltage conditioning module (2) includes a buffer capacitor (7) and an isolation resistor (8); the buffer capacitor (7) is a high-voltage pulse capacitor, directly connected in parallel across the high-voltage power supply module (1), and has filtering and energy storage functions; its capacitance value should ensure that the distortion amplitude of the output voltage of the high-voltage power supply module (1) does not exceed 10% after the vacuum gap (6) breaks down; The isolation resistor (8) is a non-inductive high-voltage resistor, connected between the buffer capacitor (7) and the high-voltage end of the vacuum gap (6); its resistance value should ensure that the current flowing from the high-voltage power supply module (1) and the buffer capacitor (7) into the broken-down vacuum gap (6) through the isolation resistor (8) is lower than the self-intercept current value of the vacuum gap (6) after the vacuum gap (6) breaks down.

6. The micro-energy intelligent aging device for a vacuum gap according to claim 1 or 2 or 3, characterized in that: The energy control module (3) includes a variable vacuum capacitor bank (9) and a rotary stepping motor (10); The variable vacuum capacitor bank (9) is composed of multiple high-voltage vacuum variable ceramic capacitors connected in series and parallel, directly connected in parallel across the vacuum gap (6); the withstand voltage of the energy control module (3) is increased by the series connection of multiple high-voltage vacuum variable ceramic capacitors; the maximum aging energy that the energy control module (3) can provide is increased by the parallel connection of multiple high-voltage vacuum variable ceramic capacitors; The rotation stepping motor (10) receives the control signal from the central control module (5), and its output end is connected to the control end of the variable vacuum capacitor bank (9). By rotating the control end of the variable vacuum capacitor bank (9), its capacitance value is changed, so as to realize the adjustment of the burn-in energy.

7. The micro-energy intelligent aging device for a vacuum gap according to claim 1, characterized in that: The central control module (5) controls the on-off of the high-voltage power supply module (1) and adjusts its output voltage, receives and stores the breakdown information transmitted by the data preprocessing part (13) of the burn-in progress evaluation module (4), and according to the carried burn-in energy control strategy, outputs the control signal to the high-voltage power supply module (1) and the rotation stepping motor (10) of the energy control module (3) in real time, so as to realize the intelligent adjustment of the burn-in voltage and the burn-in energy.

8. The micro-energy intelligent aging device for a vacuum gap according to claim 7, characterized in that: The central control module (5) opens a debugging interface, which is convenient for users to edit the burn-in energy control strategy according to the actual situation.

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