298 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.

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 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 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 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 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.

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.

This invention discloses a low-voltage pre-calibrated single-current sampling DBD equivalent parameter measurement method and system. Addressing the core shortcomings of existing DBD parameter measurement technologies, such as complex hardware, significant safety hazards from high-voltage sampling, inherent errors introduced by measurement capacitors, and imprecise derivations of single-current sampling schemes, this invention employs a two-step method to achieve full parameter measurement using only single-channel current sampling: First, pre-calibration is performed under low-voltage, undischarged conditions to obtain the DBD series equivalent capacitance and the initial phase of the excitation voltage; then, the circuit current is sampled under normal discharge conditions, and the discharge / undischarge interval is accurately divided using the sliding window variance method. Based on the data from the undischarged interval, a complete excitation voltage waveform is fitted, and finally, all equivalent parameters, including dielectric capacitance, air gap capacitance, discharge sustaining voltage, and discharge power, are calculated. This invention eliminates the need for additional hardware such as high-voltage probes and measurement capacitors, enabling online measurement of equivalent parameters.

The invention relates to the field of synchronous phase modifiers, and discloses a static synchronous phase modifier and a method and device for determining the capacitance value of a super capacitor of the static synchronous phase modifier. According to the technical scheme, the balance between the reactive compensation capability and the frequency supporting capability of the static synchronous phase modifier is ignored, and the capacitance value is calculated from multiple angles according to the relation between the kinetic energy value and the active power released by the static synchronous phase modifier and the capacitance voltage change rate in unit time. The reactive compensation capacity is improved while the frequency supporting capacity is guaranteed, capacitance values are calculated through inertia time constants, more accurate state analysis is achieved from the angle of instantaneous values, and finally the capacitance value of each super capacitor is calculated through the maximum value in the calculated equivalent capacitance values. And the balance between the reactive compensation capability and the frequency supporting capability of the static synchronous phase modifier is realized.

The application provides a touch driving circuit and a touch driving method. The touch driving circuit comprises a first power supply voltage generating circuit and a switch circuit. The first power supply voltage generating circuit is configured to generate a first power supply voltage. The switch circuit is configured to control the touch electrode to be connected to the first power supply voltage generating circuit in a first time period, to charge the equivalent capacitance of the touch electrode in the first time period, so that the voltage of the touch electrode is equal to a first intermediate voltage; control the touch electrode to be disconnected from the first power supply voltage generating circuit in a second time period, so that the voltage of the touch electrode remains the first intermediate voltage; and control the touch electrode to be connected to the first power supply voltage generating circuit in a third time period, to charge the equivalent capacitance of the touch electrode in the third time period, so that the voltage of the touch electrode is equal to the first power supply voltage; wherein the first intermediate voltage is between a ground voltage and the first power supply voltage. The technical solution can reduce the interference of touch detection on display.

A display panel and a display device, the display panel comprising a virtual gate line (G2) and a virtual conductive part (31) in a non-display area (BB), the virtual conductive part (31) is in the orthographic projection of the substrate within the orthographic projection of the virtual gate line (G2) in the substrate, the virtual conductive part (31) and the virtual gate line (G2) form an equivalent capacitance, by setting the RC load of the virtual gate line (G2) to match the RC load of the gate line (Gl) of the display area (AA), and taking the virtual gate line (G2) as the scan load of the second GOA unit (200) in the display panel which only provides a reset signal, so that the second GOA unit (200) and the first GOA unit (100) have a matched total load, thereby improving the display brightness unevenness.

The invention discloses a multi-frequency antenna radiation unit device with a decoupling function, and belongs to the field of mobile communication antennas. The high-frequency radiation unit comprises a balun electrically connected with the reflecting plate and a radiation arm connected to the balun; the low-frequency radiation unit is positioned on the periphery of the high-frequency radiation unit and is arranged on the reflecting plate; the capacitor loading assembly comprises a coupling patch connected with the radiation arm and a capacitor branch connected to the balun, the capacitor branch is located on the side, close to the reflecting plate, of the balun, the coupling patch and the capacitor branch form an additional capacitor connected with the high-frequency radiation unit in parallel, and the total equivalent capacitance of the high-frequency radiation unit is changed through the additional capacitor; therefore, the resonant frequency of the high-frequency radiation unit is shifted out of the low-frequency working frequency band, common-mode resonance generated when the high-frequency radiation unit and the low-frequency radiation unit are adjacently arranged is eliminated, the standing-wave ratio of a low-frequency port is improved, the working bandwidth is widened, distortion of a low-frequency radiation pattern is eliminated, and the coverage quality of a base station is guaranteed.

This application discloses a delay prediction method, apparatus, device, and storage medium. The delay prediction method includes: acquiring the unit characteristic information of each unit in a circuit and the characteristic sequence of each unit's interconnection; calculating the equivalent capacitance value of the interconnection path between units based on the capacitance and resistance values ​​of each unit's interconnection, and determining the target interconnection delay characteristics between units based on the equivalent capacitance values; determining the unit delay characteristics of each unit based on the equivalent capacitance values ​​and unit characteristic information; inputting the interconnection delay characteristics and unit delay characteristics into a preset delay prediction model; and performing prediction processing on the interconnection delay characteristics and unit delay characteristics based on the delay prediction model to obtain the delay result of the circuit. This application equates the capacitance and resistance values ​​of each unit's interconnection to equivalent capacitance values, overcoming the deficiency in related technologies where the load capacitance ignores the resistance shielding effect, thereby reducing the error of the load capacitance and improving the accuracy of timing prediction.

This invention discloses a method for calculating the parameters of a constant AC voltage controller in a flexible DC converter station, including obtaining the short-circuit ratio S of the flexible DC converter station connected to a weak AC system. scr Obtain the equivalent capacitance C at the AC system connection point of the flexible DC converter station. pcc Obtain the simplified AC voltage closed-loop transfer function F. uu (s); Obtain the initial value K of the simplified AC voltage closed-loop transfer function unit step response. stepu and equivalent time constant τ u ; Calculate the constant AC voltage controller parameter k puac and k iuac Obtain the active power controller parameters and verify the calculated constant AC voltage controller parameters k. puac and k iuac Does the parameter constraint condition meet? This invention, through the proposed method for calculating the parameters of the constant AC voltage controller in flexible DC converter stations, reduces the time spent by engineering researchers in selecting outer loop controller parameters and improves research efficiency.

The utility model discloses a motor and electrical equipment, and the motor includes: stator subassembly, stator subassembly includes stator core, rotor subassembly, rotor subassembly includes rotor main body and is worn in rotor main body's rotor shaft, two bearing seats, two bearing seats are arranged respectively in rotor main body's axial both sides, and rotor shaft passes through two bearings and is supported and is installed in two bearing seats, and bearing includes inner ring and outer ring, and inner ring is connected with rotor shaft electricity, and outer ring is connected with bearing seat electricity, capacitor, capacitor, stator core and one of bearing seat series connection, and two bearing seats pass through first conducting part electricity and are connected, so that capacitor, stator core and two bearing seats form equivalent capacitance. According to the utility model embodiment's motor balances the inner ring and outer ring of bearing, effectively reduces the voltage difference of bearing inner ring and outer ring, improves the problem of bearing electric corrosion, is favorable for reducing bearing noise.

A compensation circuit of realizing equivalent capacitance amplification is provided. The compensation circuit includes an error amplifier, a resistor and a capacitor. A first terminal of the resistor is connected to a first output terminal of the error amplifier. A second terminal of the resistor is connected to a second output terminal of the error amplifier and the capacitor. An amplified error current signal outputted from the first output terminal of the error amplifier flows through the resistor, and is then divided into a capacitor charging signal and an error amplified reverse current signal. The capacitor charging signal flows to the capacitor. The error amplified reverse current signal flows through the second output terminal of the error amplifier into the error amplifier. The error amplified reverse current signal is larger than the capacitor charging signal.

The application discloses a tobacco cut tobacco variable frequency motor state monitoring method based on a common mode loop and belongs to the motor state monitoring field. In view of the problem that early-stage faults of insulation deterioration of a variable frequency motor are difficult to detect in a high-dust, high-humidity and strong electromagnetic interference environment of a tobacco cut tobacco workshop, the application utilizes the correlation characteristics between a common mode loop signal and a motor insulation state, firstly establishes a common mode loop impedance model considering a common mode inductance of a stator winding, an inter-turn equivalent capacitance and a stray capacitance to ground, and calculates a common mode loop resonance frequency; then high-frequency oscillation loop models and medium-frequency oscillation loop models are respectively constructed to obtain an analytical relationship between a common mode current oscillation frequency and an insulation capacitance; a variational mode decomposition algorithm is adopted to separate multi-frequency oscillation characteristics in the common mode current, and high-frequency and medium-frequency common mode oscillation frequencies are extracted; and through online monitoring of an oscillation frequency drift amount, the deterioration degree of phase terminal insulation and internal insulation to ground of the motor winding is evaluated in real time. The application realizes non-invasive online precise monitoring of early-stage insulation faults of the tobacco cut tobacco variable frequency motor, and effectively reduces the risk of unplanned shutdown of a cut tobacco production line.