408 results about "Equivalent capacitance" patented technology

The invention relates to the field of motor health management and predictive maintenance, in particular to a motor stator winding insulation state evaluation method and system based on a digital model. Comprising the following steps: S1, collecting high frequency of a motor stator winding, and generating multi-physical-quantity real-time data; s2, calculating a dynamic capacitance reference value according to real-time data of multiple physical quantities; s3, performing subtraction operation on the high-frequency equivalent capacitance measurement value and the dynamic capacitance reference value, and extracting an insulation degradation residual signal; s4, constructing a self-adaptive dynamic detection threshold according to multi-physical-quantity real-time data; s5, judging whether the absolute value of the insulation degradation residual signal is greater than a self-adaptive dynamic detection threshold or not: if so, judging that an insulation degradation event occurs; if not, judging that the operation state is a normal operation state; and S6, in response to the insulation degradation event, updating the insulation degradation index, and generating insulation state evaluation based on the updated insulation degradation index. According to the invention, false alarm under severe load fluctuation is avoided, and the accuracy and reliability of evaluation are significantly improved.

Provided is a resonant converter capable of adaptively tuning a quality factor based on load. The resonant converter includes a resonant tank having an inductor part whose inductance is tunable according to a first control potential, a magnetizing inductor, and a capacitor part whose capacitance is tunable according to a second control potential. The resonant converter detects the rectifying current of its output stage for responding to the load state of the resonant converter. The resonant converter outputs the first and second control potentials in response to the load state, tuning the equivalent inductance of the inductor part, the equivalent capacitance of the capacitor part, or both, thereby changing the quality factor of the resonant converter.

The invention relates to the technical field of water level monitoring, in particular to a distance detection method and system of a water level sensor, a medium and equipment. The scheme comprises the following steps: arranging a non-contact distance capacitance change detection structure; calculating the equivalent volume value of the cross-air water level; setting a reference capacitance value according to the change condition of the equivalent capacitance value; setting the change relation between the height change of water and the equivalent capacitance through linear fitting according to the reference capacitance value; according to the change relation between the water height change and the equivalent capacitance, the equivalent capacitance is collected in real time, and the water level height is obtained through calculation; and according to the water level height, displaying the currently acquired water level acquisition value in real time. According to the scheme, a water level non-contact measurement method and a calculation method are designed, and online water level detection and display are achieved.

The invention discloses an ultra-large octave wave absorber based on a photoconductive material, and belongs to the field of electromagnetic metasurfaces and metamaterials. Comprising a light response wave-absorbing metasurface and a light driving module capable of projecting different patterns on the surface of the light response wave-absorbing metasurface, array wave-absorbing units of different sizes are obtained on the light response wave-absorbing metasurface by switching the projected patterns, and impedance of a target frequency band is matched by changing equivalent capacitance / inductance of a wave-absorbing unit structure; the light driving module can project a preset light pattern on the light response wave-absorbing metasurface, so that the equivalent impedance distribution of the light response wave-absorbing metasurface is changed; according to the light response wave-absorbing metasurface, the conductivity distribution of the metasurface units is changed through light control, and the wave-absorbing frequency band is adjusted in real time, that is, dynamic adjustment of the wave-absorbing performance is achieved through non-contact light control. According to the invention, the limitation of narrow bandwidth and passive fixation of a traditional wave absorber is broken through, and electromagnetic wave control with ultra-large octave, high absorptivity and real-time reconfigurability is realized.

The invention relates to the technical field of power electronics, in particular to a DC deicing current oscillation suppression method and system, and the method comprises the steps: obtaining an equivalent inductance value and an equivalent capacitance value according to the operation environment data of a DC deicing system; according to the equivalent inductance value and the equivalent capacitance value, when the current state of the direct current deicing system does not meet the current oscillation suppression condition, generating a valve group control optimization strategy based on the equivalent inductance value and the operation environment data; extracting current oscillation characteristic data according to the current waveform data and determining the ice melting efficiency according to the current oscillation characteristic data in the process of controlling the direct current ice melting system to execute ice melting operation through the valve group control optimization strategy; and when the ice melting efficiency does not reach the standard, optimizing the valve group control optimization strategy by using the current oscillation characteristic data and a multi-objective optimization algorithm, and outputting an optimal ice melting control strategy. By dynamically optimizing the valve group control strategy, the ice melting efficiency is considered while the current oscillation is suppressed, and the stable operation of the direct current ice melting system is ensured.

The invention relates to the technical field of vibration sensors, and discloses a high-precision vibration spectrum sensor, which comprises a shell, a sealing cover is embedded in the shell, the top of the sealing cover is flush with the top of the shell, and the shell and the sealing cover form a closed space; and the sensor mechanism is arranged in an inner space defined by the shell and the sealing cover, the sensor mechanism comprises an insulating cylinder, the outer wall of the insulating cylinder is fixedly connected with a connecting block, the insulating cylinder is fixedly connected to the inner wall of the shell through the connecting block, and the interior of the insulating cylinder is fixedly connected with a first electrode plate and a second electrode plate. The sensor is excellent in detection performance and capable of accurately capturing vibration signals, the core component is made of high-quality materials, the spring wire is stable in elasticity and resistant to corrosion, the ball body responds to high-frequency vibration rapidly, the electrode plates reduce signal loss, vibration is converted into electric signals through equivalent capacitance changes, various curves can be generated, early fault features can be recognized in an assisted mode, and the detection accuracy is improved. And the detection accuracy and completeness are ensured.

The invention discloses a method for monitoring the insulation state of a stator winding of an injection unit based on neutral point harmonic frequency sweeping. The invention provides an active online monitoring method based on harmonic injection for stator winding insulation of a full-power variable-speed pumped storage unit. A common-mode loop is constructed for a motor stator winding of a network side transformer neutral point ungrounded system through a motor neutral point grounded transformer, and therefore online monitoring of the insulation state of a motor stator is achieved. In order to solve the measurement problem of the full-power variable-speed pumped storage unit under the large-current working condition, a neutral point outgoing line current detection technology is adopted. A machine end large current interference area is avoided, monitoring is carried out on the primary side of the grounding transformer, transmission errors are avoided, and the measurement precision and reliability of insulation monitoring signals are remarkably improved. According to the invention, harmonic injection is carried out by avoiding an inherent common-mode component of a unit, a monitorable leakage current signal is enhanced, and the accuracy of insulation equivalent capacitance calculation is ensured.

The invention provides an excitation amplitude automatic closed-loop control system and method for a DLCP test. The system comprises a multi-frequency alternating current excitation and direct current bias voltage applying module which is used for automatically applying alternating current excitation signals and direct current bias voltage signals according to a preset excitation amplitude sequence under a plurality of test frequencies; the PID closed-loop control module is used for performing closed-loop correction on the applied voltage according to the response of the test port of the tested semiconductor device, so that the condition of the applied voltage at the test port meets a preset requirement; the capacitance measurement module is used for acquiring an equivalent capacitance response signal of the tested semiconductor device; the capacitance test data caching module is used for performing associated marking and classified caching on the capacitance test data according to the test frequency, the excitation level and the bias voltage set point; and the main control module is used for coordinating automatic test processes under the conditions of a plurality of test frequencies and different excitation amplitudes and outputting corresponding capacitance test data so as to improve the consistency, stability and automation degree of the DLCP test.

The embodiment of the invention relates to the technical field of transformer fault detection, and discloses a transformer winding fault detection method and system based on frequency response and a medium, and the method comprises the steps: determining the equivalent inductance and equivalent capacitance of a transformer winding; and calculating a first-order grounding coefficient of driving point admittance by using the peak frequency and the valley frequency when the neutral point is grounded, and calculating a first-order open-circuit coefficient by using the peak frequency and the valley frequency when the neutral point is open-circuit. A first difference function is constructed through the equivalent inductance, the scaling rate and the first-order grounding coefficient, and a second difference function is constructed through the equivalent capacitance and the first-order open circuit coefficient. And fault detection of the transformer winding is carried out according to a comparison condition between fluctuation of the first difference function and the second difference function and a preset threshold value, and early sensitive detection is realized.

The invention provides a method and device for determining the health state of a supercapacitor, and relates to the technical field of supercapacitors, and the method comprises the steps: obtaining the voltage variation and the current variation of the supercapacitor in the operation process; determining a target equivalent resistance value according to the voltage variation and the current variation; determining a target equivalent capacitance value according to the voltage variation and the current value in the corresponding time period; determining a resistance growth rate and a capacitance attenuation rate according to the target equivalent resistance value and the target equivalent capacitance value; and determining the health state of the supercapacitor according to the resistance growth rate and the capacitance attenuation rate. Therefore, the capacitance attenuation rate and the ESR growth rate can be extracted online based on the voltage data and the current data acquired in real time without interrupting the system or adding the test current in the equipment operation process, the process is simplified, and the accuracy and the reliability of determining the health state of the supercapacitor are also improved through the real-time data.

The invention relates to an offshore wind power tower tube corrosion detection method and system based on a microprobe technology, and the method comprises the following steps: placing a microprobe corrosion detection device on a to-be-detected offshore wind power tower tube, and setting a probe interval between a signal transmitting probe and a signal receiving probe according to the thickness of an anticorrosive coating of the offshore wind power tower tube and the corrosion condition; in the process that the microprobe corrosion detection device moves on the offshore wind power tower drum to be detected, the signal emission probe emits an alternating current signal according to a preset frequency, and the emitted alternating current signal is propagated by taking the anti-corrosion coating as a medium and penetrates through the coating to enter the main body steel structure; the emitted alternating current signal is transmitted in the main body steel structure and then returns to the signal receiving probe through the anti-corrosion coating; the alternating current signals collected by the signal receiving probe are analyzed, metal resistance and capacitance effect equivalent capacitance values of the main body steel structure in the offshore wind power tower are obtained, and the corrosion conditions of the main body steel structure and the anticorrosive coating of the offshore wind power tower are judged according to the obtained metal resistance and equivalent capacitance values.

A circularly polarized antenna includes a plurality of radiation units configured in a rotational symmetry manner, and a feed network connected to the plurality of radiation units. Each radiation unit comprises a patch element and a short circuit wall which is connected with the patch element and is suitable for enabling the patch element to be short-circuited. Different from the traditional sequential phase feed, the sequential phase feed only depends on the physical length of the delay line to realize the phase change, and the reactance loading feed line ingeniously utilizes the equivalent capacitance and inductance to change the phase. The method does not need to depend on a long delay line, and stable phase difference can be realized in a wide frequency band.

The invention relates to the technical field of circuit board detection, in particular to a printed circuit board drilling quality detection method and device, and the method comprises the steps: injecting sinusoidal current signals with preset frequencies into a plurality of test points of a to-be-detected drilling region of a printed circuit board, extracting impedance values under each frequency component, and calculating the drilling quality of the printed circuit board; constructing an equivalent impedance spectrum containing a real part and an imaginary part according to the impedance value; according to the interlayer structure and the equivalent impedance spectrum of the printed circuit board, calculating equivalent resistance and equivalent capacitance of the drilling area to be measured to form a characteristic parameter set; comparing the data of each grid point in the characteristic parameter set with a preset threshold value, and integrating the grid points exceeding the preset threshold value to generate a defect state mark; and performing electrical topology constraint on the defect state mark to generate a defect positioning result. According to the invention, hidden defects in the drill hole and interlayer structures can be deeply detected, the electrical performance of the drill hole can be comprehensively evaluated, and accurate defect positioning and state marking can be provided.

The embodiment of the invention provides a packaging chip, a radio frequency communication module and communication equipment, and is applied to the technical field of semiconductor packaging. The package chip includes a wafer. The packaging chip further comprises at least one first attenuation element and at least one first tuning element, the first attenuation element is an equivalent capacitor or an equivalent resistor, and the first tuning element is an equivalent capacitor, an equivalent inductor or an equivalent resistor. Wherein the wafer is provided with a filtering structure, and the filtering structure comprises a first filtering resonance structure. The at least one first attenuation element is connected with the first end and the second end of the first filtering resonance structure so as to form a parallel structure with the first filtering resonance structure. The first end of each first tuning element is connected to a transmission path formed by the first end and the second end of the first filtering resonance structure and the at least one first attenuation element, and the second end of each first tuning element is grounded. According to the embodiment of the invention, the suppression degree and / or isolation degree of the filter device are / is greatly improved on the basis of not increasing the signal insertion loss.

The invention discloses a voltage transformer intelligent inductance adjustment verification method and device based on a current inversion capacitor, and the method comprises the steps: obtaining a preset excitation voltage and an adjustable sweep frequency, and carrying out the sweep excitation of an inductance adjustment resonant circuit according to the preset excitation voltage and the adjustable sweep frequency; acquiring current sampling data of the inductance-adjusting resonance circuit; performing frequency domain analysis on the current sampling data, and calculating an equivalent capacitance value and a resonance state parameter of the inductance-adjusting resonance circuit according to a frequency domain analysis result; and the air gap length and the winding turns of the reactor are adaptively adjusted based on the resonance state parameters. The capacitance value and the resonance state parameter of the resonance circuit are calculated through inversion of the current frequency domain analysis result, dual-mode inductance adjustment closed-loop control is achieved based on the capacitance value and the resonance state parameter, the problems that an existing manual inductance adjustment mode depends on artificial experience and is tedious in operation and low in efficiency are solved, the method can adapt to a high-capacity mutual inductor, meanwhile, a resonance point is accurately locked, and the control precision is improved. And wide-range and high-precision inductance adjustment is realized.

A three-phase wireless electric energy transmission device disclosed by the present invention comprises a three-phase inverter, a three-phase switch capacitor, a coil magnetic field coupling structure and a rectifier, the coil magnetic field coupling structure comprises a primary coil and a secondary coil which are arranged in mirror symmetry, the primary coil is provided with two layers, each layer comprises a three-phase coil, each phase coil occupies a 120-degree angle range of the circumference, and the rectifier is connected with the primary coil and the secondary coil. The two layers of coils form a staggered angle, each phase of switched capacitor of the three-phase switched capacitor comprises a first capacitor branch and a second capacitor branch which are arranged in parallel, the first capacitor branch is provided with a first capacitor, and the second capacitor branch comprises a second capacitor and a switch module which are arranged in series; the switch module adjusts the equivalent capacitance value of the second capacitor branch through the duty ratio and adjusts the transmission power of the three-phase wireless power transmission device. The invention further discloses a load power adjusting method of the three-phase wireless power transmission device, the transmission efficiency can be kept unchanged within the adjusting range, and soft switching can be achieved within the adjusting range.

The invention relates to the technical field of crystal growth, and discloses a method and a system for electrochemical in-situ characterization of crystal growth interface area change, and the method comprises the following specific steps: in a crystal growth process by a Czochralski method, measuring impedance between a seed crystal and a crucible containing a melt in real time to obtain an electrochemical impedance spectrum at the growth stage; performing equivalent circuit fitting on the measured electrochemical impedance spectrum to obtain fitting parameters of a corresponding circuit element and calculating equivalent capacitance of a growth interface of the electrochemical impedance spectrum; and calculating the crystal growth interface area through a parallel plate capacitor model based on the equivalent capacitance value. The method solves the problem that the prior art is not suitable for monitoring the crystal growth interface, and has the characteristics of high precision, nondestructive detection, no influence on crystal growth, simple process and controllable cost.

The invention is applicable to the field of intelligent wearable products, and provides intelligent glasses with a wearing detection function and a wearing detection method.The intelligent glasses comprise a glasses frame and two glasses legs, a circuit board is arranged in at least one glasses leg, and at least one processor and at least one sensor connected with the processor are installed on the circuit board; the tail end of the at least one glasses leg is fixedly connected with a metal tail pin, and the metal tail pin is electrically connected to the sensor through an FPC (Flexible Printed Circuit); the sensor is used for collecting capacitance parameters of equivalent capacitance formed by the metal tail needle and the skin of a user; and the processor is used for judging whether the intelligent glasses are in a wearing state or not according to the capacitance parameters and controlling the working state of the intelligent glasses according to a judgment result. The whole detection process does not need user intervention, automatic judgment is achieved through electric signal changes generated by physical contact of the metal tail needle and the human skin, and then the working state of the intelligent glasses is automatically controlled according to the judgment result.

The invention relates to the technical field of electrical equipment insulation tests, and discloses a medium-voltage cable variable-frequency resonance voltage-withstanding test system and a medium-voltage cable variable-frequency resonance voltage-withstanding test method. The method comprises the steps of configuring a test loop and setting related parameters, and presetting a target test voltage, test time, a system quality factor range, a local discharge capacity threshold and a current change rate threshold based on a cable model, a cable length, a laying environment temperature and an equivalent capacitance. And executing frequency scanning in a preset frequency range through an adaptive step length strategy, adjusting the step length according to the current response, identifying the resonant frequency and verifying the quality factor of the system. In the test process, the loop current change rate, the partial discharge capacity and the equipment temperature are monitored in real time, a protection mechanism is triggered according to abnormal characteristics, and insulation state diagnosis is completed. When the test is ended, voltage is reduced at a controllable rate, residual charges are dissipated, and a test report is automatically generated. The method improves the accuracy and safety of the test, and is suitable for various field conditions.

The invention relates to the technical field of microwave radio frequency, in particular to a third-order tuning low-pass filter. Comprising an input coupling inductor L1, a first interstage coupling inductor L2, a second interstage coupling inductor L3, an output coupling inductor L4, a first tuning capacitor C1, a second tuning capacitor C2 and a third tuning capacitor C3, the first tuning capacitor C1, the second tuning capacitor C2 and the third tuning capacitor C3 are all adjustable capacitor arrays, and each tunable capacitor is composed of a plurality of capacitors and PIN diodes. By changing the control signal into a high level or a low level, the conduction or cut-off state of the PIN diode is changed, and then the equivalent capacitance value of the whole tuning capacitor is changed, so that the frequency of the filter is correspondingly changed, and different working frequency bands are obtained. The three-order tuning low-pass filter can effectively restrain third and more harmonic waves at the rear ends of the frequency hopping filter and the power amplifier, and the cut-off frequency of the three-order tuning low-pass filter can change along with control signals.

The present application provides an image sensor, a working method thereof, and an electronic device. A bit line module is provided, and in a first state, a low-gain reset signal is sampled into a first equivalent capacitor; in a second state, a high-gain reset signal and a high-gain image signal are sampled and outputted in sequence through a second gain output bit line; when the second state returns to the first state, the low-gain reset signal sampled in the first equivalent capacitor is outputted through the first gain output bit line, and then the low-gain image signal is sampled and outputted through the first gain output bit line; at the same time, a gain output selection circuit is connected to a matching readout circuit to achieve effective image quantization; while achieving a high dynamic range of the image sensor, the cost and size of the image sensor are reduced; because there is no need to sample and hold the output of the pixel circuit to reduce the KT / C noise of the circuit, the circuit noise level is lower, further improving the performance of the image sensor.

The present application provides an automatic sensing device for the content of an aerosol-forming substrate and an electronic atomization device, including a capacitance measurement circuit and a controller. Among them, the first electrode of the capacitance measurement circuit is a heating component, and the second electrode of the capacitance measurement circuit is the aerosol-forming substrate; the controller disconnects the heating circuit of the electronic atomization device and connects the first electrode and the second electrode to obtain the content of the aerosol-forming substrate of the electronic atomization device according to the measured capacitance value of the equivalent capacitance formed by the heating component and the aerosol-forming substrate. Thus, the purpose of measuring the content of the aerosol-forming substrate of the electronic atomization device is achieved without adding additional electronic components, with low cost and easy implementation.

This invention discloses a live-line detection device and method for partial discharge in GIS (Gas Insulation System), relating to the field of live-line detection of power equipment. The equivalent capacitance between the primary and secondary windings of a current transformer coil is used as a pulse signal coupling channel. Two sets of pulse current signals within the high-voltage conductor of the GIS are acquired through these two pulse signal coupling channels. Then, the partial discharge voltage signal of a specified frequency is extracted through a pulse partial discharge detection circuit. The two extracted pulse signals are output to a differential mode comparison and acquisition module. This module compares the pulse signals input from the two channels, effectively eliminating interference signals. This invention simultaneously solves two problems in GIS live-line partial discharge pulse detection: pulse coupling and high-voltage side partial discharge interference during live operation. It achieves accurate detection of partial discharge during GIS operation, ensuring the safe and stable operation of GIS electrical equipment.

Embodiments of the present disclosure relate to reverse wireless charging. A method and system for operating a power circuit capable of transmitting wireless power and receiving wireless power are provided. The method includes determining that the power circuit is operating in a receive mode and, based thereon, having a first equivalent capacitance. The method further includes determining that the power circuit is operating in a transmit mode and, based thereon, having a second equivalent capacitance. The first equivalent capacitance is different from the second equivalent capacitance.

The embodiment of the present application relates to the technical field of transformer fault detection, and discloses a transformer winding fault detection method, system, device and medium based on current change, which comprises the following steps: applying a current excitation to the transformer winding, wherein the current excitation is determined according to the normal working current of the transformer winding after equal ratio scaling at a preset scaling rate; determining the self-inductance of the transformer winding according to the current excitation and the self-inductance coefficient of the transformer winding, and determining the mutual inductance of the transformer winding according to the current excitation and the mutual inductance coefficient of the transformer winding; determining the equivalent inductance according to the self-inductance and the mutual inductance; obtaining the series capacitance and the grounding capacitance of the transformer winding, determining the equivalent capacitance according to the series capacitance and the grounding capacitance; determining a first difference function according to the equivalent inductance and the preset scaling rate, and determining a second difference function according to the equivalent capacitance; and performing the fault detection of the transformer winding according to the comparison between the fluctuations of the first difference function and the second difference function and the preset threshold, so as to realize early and sensitive detection.

The application provides a non-continuous three-phase rectifier adjustable power decoupling method, and relates to the field of power electronics. The method is characterized in that a capacitor equivalent circuit is connected in parallel to the DC side of a three-phase PWM rectifier, the capacitor equivalent circuit is composed of a first capacitor connected in series with an active negative capacitor circuit, and a digital signal controller is used to sample the relevant voltage and current signals of the AC side and the DC side, and the active negative capacitor capacitance is adjusted by controlling the switching tube, so that the equivalent capacitor circuit can be flexibly adjusted. The application does not require an additional DC power supply, the capacitance and inductance of the passive device used are small, and the volume advantage is significant. The closed-loop control has high precision and equivalent inhibition effect as the traditional large capacitor. The equivalent capacitance is adjusted only by software, the external physical structure does not need to be changed, and the adjustment range is wide. The preset DC side voltage fluctuation amplitude can be calculated and adjusted automatically, different unbalanced working conditions can be adapted, the fluctuation suppression demand can be met, different working modes can be switched according to the AC side working condition, and the application is not continuously operated, so that the switching loss is lower.

The invention discloses a broadband strong-absorption microwave metamaterial design and preparation method based on impedance control, and belongs to the field of electromagnetic absorption metamaterials. The invention aims to solve the problem that a microwave absorption metamaterial is difficult to realize wide absorption bandwidth and strong absorption intensity at the same time. The method comprises the following steps of: 1, solving an impedance value range of a resistive film layer on the surface of the microwave absorption metamaterial; 2, further extracting the available value ranges of the equivalent resistance and the equivalent capacitance of the resistive film layer; 3, traversing value ranges of the equivalent resistance and the equivalent capacitance, and collecting phase information of electromagnetic waves reflected by the corresponding metamaterial; 4, calculating a reflected electromagnetic wave phase difference; 5, selecting two metamaterial units of which the difference between the average value of the absolute values of the phase differences and the pi is minimum in the target frequency band; and 6, forming a new metamaterial unit through chessboard type distribution and arrangement, and realizing the design of the broadband strong-absorption metamaterial through common regulation and control of amplitude and phase. The method has universality and can be used for efficiently designing other metamaterial microwave absorbers with target performance.

A method comprises discharging electrical energy from an intermediate circuit comprised in the apparatus, measuring a direct current voltage, and inputting measured values to a parameter estimator for the intermediate circuit. The parameter estimator comprises at least a first parameter and a second parameter whose values are determined based on an equivalent capacitance value of the intermediate circuit, an equivalent resistance value of the intermediate circuit and an electrical load power value of the intermediate circuit, the parameter estimator outputting values for time constant and values for power-to-capacitance ratio of the intermediate circuit. The method further comprises storing values at least temporarily for condition monitoring.

The invention relates to a three-phase single-stage isolation ACDC device and a server power supply, a three-phase single-stage isolation ACDC circuit is arranged on a substrate, a quiet potential assembly is arranged between the three-phase single-stage isolation ACDC circuit and a shell, and the quiet potential assembly is connected to the three-phase single-stage isolation ACDC circuit. And the first capacitor, the second capacitor and the third capacitor of the three-phase input circuit are connected to form a common end. Therefore, each moving point and the quiet potential assembly on the three-phase single-stage isolation ACDC circuit can be equivalent to a parallel plate capacitor, and after the three-phase single-stage isolation ACDC circuit operates in any phase and generates common-mode noise, common-mode current flows through the second end of the first capacitor, the second end of the second capacitor and / or the second end of the third capacitor through the equivalent capacitor, so that the common-mode noise is generated. And finally, the noise flows back to the noise source in the three-phase single-stage isolation ACDC circuit. Common-mode noise generated by the three-phase single-stage isolation ACDC circuit and the shell is avoided, and the purpose of improving and solving common-mode noise interference generated by the three-phase single-stage isolation ACDC circuit on adjacent electric equipment is achieved.

The invention relates to a method and system for detecting the vacuum degree of a vacuum arc-extinguishing chamber based on high-frequency discharge and spectral analysis, and the method comprises the steps: exciting the interior of the vacuum arc-extinguishing chamber to generate field emission current through a high-frequency electric field, and obtaining a high-frequency current peak value through the spectral analysis of the field emission current; the vacuum degree is determined according to a pre-constructed vacuum degree-high-frequency current peak value standard relation curve, a high-frequency power source is connected to a vacuum arc extinguish chamber, the output voltage of the high-frequency power source is gradually increased until a vacuum gap breaks down, the voltage waveform in the process is recorded, and the total current of a loop is calculated; calculating a capacitive current component by combining the equivalent capacitance of the loop; and selecting a stable current section between two dielectric breakdown events in the total current, intercepting a current peak signal in the section, and subtracting the capacitive current component from the total current corresponding to the peak signal to obtain the field emission current. Compared with the prior art, the method has the advantages of high sensitivity, simplicity and convenience in operation, accurate result and the like.