83results about How to "Suppression of common mode interference" patented technology

A detection system of high sensitivity DC local discharge on large-capacity high voltage power device is prepared for providing high voltage DC voltage to balance detection impedance circuit by DC high voltage source, picking up local discharge signal of detected sample by balance detection impedance circuit, sending local discharge signal to differential amplification filtering circuit to carry out differential amplification filtering treatment than sending treated signal to data collection and analysis unit for obtaining detection and analysis result of local discharge signal.

The invention discloses a digitized high-power microwave diode reversed dynamic waveform and loss power testing system. The system comprises a low-noise power circuit used for providing direct voltage and applying reverse bias voltage to a diode to be tested, a forward adjustable current source circuit used for providing multiple adjustable forward currents for the diode to be tested, an edge adjustable pulse generating circuit used for providing multiple adjustable pulse modulation signals for the diode to be tested, a reverse dynamic current and voltage waveform testing and peak detection circuit used for acquiring the reverse dynamic current and voltage waveforms and peak signals of the diode to be tested, a dynamic current waveform sampling circuit used for processing the peak signals into analog signals, a C parameter testing circuit used for measuring the ratio of reverse peak voltage to bias voltage, and a central processing unit used for data processing. According to the system, by detecting performance parameters, including the reverse dynamic current, reverse dynamic voltage and loss power, of the diode, the purposes of well selecting and using the diode and improving the reliability of the diode are realized.

The invention discloses a direct frequency output vibratory gyroscope structure, the aim is to design and manufacture a frequency modulation output vibratory gyroscope based on the plane manufacturing technology, so that the output signal anti-interference capability of the vibratory gyroscope is improved. The design of the vibratory gyroscope is characterized in that: (1) by adopting frequency local modulation means, the signal loss is greatly reduced, and the weak Coriolis effect localized frequency modulation is achieved; (2) by adopting a frame mass block supporting structure, the transverse Coriolis acceleration is correspondingly and significantly enlarged, which is effectively imposed on the axial direction of a resonator beam; (3) two resonator beams adopt a differential resonant structure, and a plurality types of the common-mode interferences can be inhibited, such as temperature stress; and (4) the plane project design is easy to adapt to the related technology of wire cutting machining or MEMS, and is easy to be miniaturized.

The invention discloses a transform circuit adopting a symmetrical cross-linked structure, comprising two like transformers, and the two transformers are symmetrically cross-linked. In the invention, the transform circuit with the symmetrical cross-linked structure is adopted, thereby the voltage transmission ratio and the regulation performance of a Boost or Buck transformer are obviously improved, the voltage stress of power devices is obviously reduced, and the conversion efficiency of the transform circuit is equivalent to or higher than that of the Boost or Buck transformer within a larger application scope,.

The invention relates to a large-airspace high-dynamic navigation guidance and control integrated system and method. The system comprises an optical fiber inertia measurement unit, a multimode GNSS satellite receiver, a dual-core embedded flight control computer, a high-overload-resistant miniature black box, a combiner, a dual-path satellite antenna, a secondary power supply conversion module, abase and a shell. A navigation guidance and control program is run in the dual-core embedded flight control computer, the navigation program adopts a robust Kalman filtering algorithm to adjust Kalmanoptimal gain and posterior estimation error covariance on line, and the guidance and control program adopts a scheme attack angle on-line planning and self-adaptive control parameter design method. The system has the advantages of low cost, high integration level, small volume, high overload resistance, simplicity, economy, reliability and the like.

The invention provides a control and drive circuit applied to a synchronous rectification switching mode power supply. The circuit comprises a primary switching tube controller, a logic circuit, a switching circuit and a synchronous rectifier tube controller, wherein the primary switching tube controller is used for generating a primary switching tube control signal, the logic circuit is used for generating a first control signal according to received primary switching tube control signal, the switching circuit is used for generating a second control signal according to the received first control signal, and the synchronous rectifier tube controller is used for generating a synchronous rectifier tube control signal according to the received second control signal and guaranteeing phases of the primary switching tube control signal and the synchronous rectifier tube control signal to be the same or inverse according to a topological structure of the synchronous rectification switching mode power supply. The invention further provides a control and drive method, so that the synchronous rectifier tube control signal for controlling on and off of a synchronous rectifier tube is generated according to the primary switching tube control signal, the problem of cross connection of the synchronous rectification power supply is solved, and high frequency, low cost, small size and high efficiency of the synchronous rectification switching mode power supply are achieved.

The invention relates to a dual-way passing detector of opposite-mounted sphere bed high temperature gas-cooled reactor fuel sphere, comprising an exciting unit, a sensing unit and a signal conditioning unit, wherein, the sensing unit comprises an exciting coil and two detection coils; the exciting coil and the detection coils are symmetrically arranged on two sides of a sphere conveying steel tube; signal power of sinusoidal voltage is amplified by the exciting unit and transmitted to the exciting coil of the sensing unit; the two detection coils of the signal conditioning unit and the sensing unit are connected, two ways of voltage signal of the detection coils are calculated and processed, and sine-wave voltage signal indicating sphere passing and passing direction is outputted; non-contact detection is adopted for detecting radioactive fuel sphere. The invention has the advantages of high signal-to-noise ratio of output signal, strong interference resistance, high resolution for continuous passing and passing of more than half a sphere as well as simple structure, convenient installation without damage to sphere conveying steel tube in construction.

The invention relates to the field of MEMS (Micro Electro Mechanical System) inertial devices, in particular to a high-accuracy fully differential capacitance-voltage conversion circuit system. The high-accuracy fully differential capacitance-voltage conversion circuit system comprises a driving signal generation part, a fully differential charge amplifier and capacitance compensation arrays. A whole conversion circuit and a sensor sensitive structure still adopt an output mode in single-ended connection, and a fully differential circuit structure is realized through time division multiplexing; a circuit adopts a switch capacitance structure for removing the influence of parasitic capacitance, main signal channels adopt a correlated double sampling technology for removing low-frequency noise and detuning, the capacitance compensation array is capable of correcting the detuning and non-linearity of the sensor sensitive structure. According to the high-accuracy fully differential capacitance-voltage conversion circuit system disclosed by the invention, the influence of the parasitic capacitance can be effectively inhibited, common-mode interference generated by switch charge injection and substrate noise can be reduced, harmonic distortion of the circuit is reduced, the linearity of an accelerometer system is increased, and zero drift is inhibited.

The invention discloses a method suitable for suppressing common mode electromagnetic interference in a wind driven generator driving system. When a switching tube operates, a parasitic capacitor between the switching tube and a radiator generates a grounding interference leak current iL, and the grounding interference leak current iL flows to a ground terminal of the radiator; a voltage change signal du / dt generated during the operation of the switching tube is connected into an input terminal of a phase inverter; under the reverse action of the phase inverter, an output terminal of the phase inverter outputs a voltage change signal which is identical with the voltage change signal du / dt in amplitude and opposite to the voltage change signal du / dt in phase; the voltage change signal forms a compensating current -iL through an isolation transformer used for preventing an interference current from flowing back and a compensation capacitor CP, and the compensating current -iL enters the ground terminal of the radiator through a wire; the grounding interference leak current iL and the compensating current -iL are identical in amplitude and opposite in phase, so that the grounding interference leak current iL and the compensating current -iL offset each other, and common mode interference to conduction of the grounding interference leak current iL is suppressed. According to the method, on the basis of lowering the complexity and cost of the system, common mode interference in the driving system is effectively suppressed, and the stability and electromagnetic compatibility of the system are improved.

The invention discloses an infrared signal amplification circuit which comprises a photosensitive diode, an NPN type triode, a trans-impedance amplifier, a first voltage source port, a second voltagesource port and a detection signal output port, wherein the trans-impedance amplifier is used for converting current output by the NPN type triode into voltage and realizing voltage amplification; Thecathode of the photosensitive diode is connected with the first voltage source port; The anode of the photosensitive diode is connected with the base electrode of the NPN type triode, the collector electrode of the NPN type triode is connected with the second voltage source port, the emitter electrode of the NPN type triode is connected with the inverting input end of the trans-impedance amplifier, and the output end of the trans-impedance amplifier is connected with the detection signal output port. The invention also discloses an infrared signal processing circuit and an infrared touch screen. By adopting a plurality of embodiments, the problem that an infrared amplification circuit in the prior art cannot detect a weak signal is solved.

The invention relates to an end screen differential digital output transformer, belonging to the field of high-voltage apparatuses. The end screen differential digital output transformer comprises a U-shaped or straight line-shaped capacitive-type primary winding, an ultracrystalline iron core coil, a silicon steel sheet iron core coil, a differential converter, an integrated terminal and the like. The end screen of the capacitive-type primary winding is divided into two segments with different lengths; two unequal capacitive currents extracted from the two segments are grounded through the input terminal of the differential converter; the output terminal of the differential converter obtains a low-voltage signal proportional to a primary voltage; the ultracrystalline iron core coil and the silicon steel sheet iron core coil can induce a low-voltage signal proportional to a primary current; and the integrated terminal converts the analog electrical signals into digital optical signals, and respectively provides the digital optical signals to a digital measurement instrument and a microcomputer protection device. The end screen differential digital output transformer has the functions of a voltage transformer and a current transformer, and the intermediate low-voltage analog signals are in a weak current range, so that the end screen differential digital output transformer is safe and reliable and has the advantages of high resistance to common mode interference, small error and high accuracy.

The invention discloses a robot signal transmission system. The system comprises a signal sampling module and a noise reduction differential module. The signal sampling module uses a signal sampler J1with a model of DAM-3056AH to sample signals of a signal emitter in a robot signal transmission system. The output end of the signal sampling module is connected with the input port of the noise reduction differential module; the noise reduction differential module sends a signal to a robot signal transmission system terminal; the noise reduction differential module uses a diode D4 and a diode D5to form an amplitude limiting circuit protection signal. Finally, a differential circuit composed of an operational amplifier AR4 and an operational amplifier AR5 and a variable resistor RW1 carriesout differential processing on the two paths of signals. Common-mode interference is suppressed, the output signal amplitude of the differential circuit can be adjusted by adjusting the loop resistance value of the variable resistor RW1, then the signal emitter E1 is triggered to work after signals are buffered through the operational amplifier AR6, a robot signal transmission system terminal canconveniently adjust the signal data size of the signal emitter in time, and the signal attenuation depth is reduced.

The invention relates to a high-performance novel television-computer integrated machine, which comprises a mainboard, a power supply module, a computer function module and a television function module, wherein the computer function module and the television function module are integrated on the mainboard; the computer function module comprises a south-north bridge core group; the television function module comprises a CPU main control unit, a CA interface unit, a PS2 interface circuit and an infrared receiving unit; and the infrared receiving unit, the CA interface unit and the PS2 interface circuit are all connected with the CPU main control unit. The high-performance novel television-computer integrated machine has the advantages of small size and light weight, compact structure, energy saving, no noise and long service life, supports modes, such as standby, dormancy to a hard disk, dormancy to a memory and the like and integrates the television function module and the computer function module into one mainboard, and therefore fussy connection wires between the television function module and the computer function module are reduced; in addition, the television function module and the computer function module are communicated in a convenient and rapid PS2 format; and a main control unit of the television function module is used as a control core, therefore convenient switchover between a television and a computer is achieved through controlling the main control unit by a remote controller.

Disclosed is a sending device for transmitting video signals with an ultrahigh resolution ratio and an ultrahigh frame rate through dual twisted pairs. The sending device comprises a chroma space conversion unit, a YUV gain control unit, an image division unit, a coding unit and a D / A conversion unit which are sequentially connected are included; as for the video signals, the RGB format is converted into the YUV format through the chroma space conversion unit, and the brightness and chroma are adjusted through the YUV gain control unit; the image division unit is used for dividing the adjusted video signals into a plurality of sub images; the coding unit is used for coding the brightness Y and the chroma UV separately; and the sub images are converted into analog signals through the D / A conversion unit so that the analog signals can be transmitted on a dual-twisted-pair transmission line. The sending device has the advantages of low structuring cost and simple mode, and is beneficial for restraining common mode interference and reducing attenuation. By means of the sending device, multi-path frequency decrease treatment is achieved, the requirement for bandwidth of each signal transmission line is lowered, the degree of distortion of transmission frequency is lowered, and meanwhile, transmission problems caused by mutual interference of brightness and chroma is effectively solved.

The invention discloses a low-noise switching mode power supply transformer. A primary winding and a secondary winding of the low-noise switching mode power supply transformer are symmetrical windings which are formed by a pair of coils with equal number of windings. The winding direction of the dotted terminal of each pair of coils is opposite. In addition, the invention discloses a low-noise switching power supply. The low-noise switching power supply comprises the disclosed transformer. Electric fields produced by high frequency alternating voltage distribution which is produced by the primary winding and the secondary winding of the transformer are cancelled out instead of reaching a secondary coil through capacity coupling between the primary level and secondary level. Therefore, common mode interference is restrained.

The invention discloses an electromagnetic interference suppressing structure and an electronic device having the same. Via disposing of a coplanar waveguide structure, a separation layer and a resonance layer, and under the coplanar waveguide structure, via connection of a conductive connection part in the separation layer and a conductor part of the resonance layer at the lower part, with such a stereoscopic structure, suppressing effect of electromagnetic interference is further improved, and better suppressing effect of electromagnetic interference is achieved.

The present invention discloses a super-resolution secondary-color differential confocal measurement method, which comprises the steps that a first differential confocal measuring device, a paralleling flat-plate correction color difference super-resolution measuring head and a computer device are provided; the thickness of the base of a super-resolution filter flat plate is precisely corrected, and the plane position adjustment of the two light beam is realized, so that the position difference of the two focus plane is equal to the sum of half of the linear measurement zone of the first differential confocal measuring device and half of the linear measuring zone of the second differential confocal measuring device. The present invention also provides a super-resolution secondary-color differential confocal measuring device. The device and the method have the advantages that on the premise of the technical advantage that the known secondary-color super-resolution differential confocal measurement technology has two independent dual-polarity tracing linearity areas, and the axial responding measuring range is maximum, so that the common mode interference can be prevented, the transverse resolution of the system is improved.

The invention discloses an active filtration method and device for simultaneously restraining difference mode interference and common mode interference. The method comprises the following steps that (1) a plurality of active power filters are respectively bridged between each power supply bus and each neutral line, and meanwhile, a current sensor is arranged on each power supply bus, and each current sensor is respectively connected to the corresponding active power filter bridged between each power supply bus and each neutral line; (2) each current sensor monitors harmonic interference current on each power supply bus; and (3) each active power filter works based on a feedback control principle, so that the harmonic interference current on the power supply bus, which is monitored by each corresponding current sensor, is minimum, and meanwhile, the harmonic current of the neutral line is minimum. According to the active filtration method and device, through a connection way of two active power filters and the ground wire, a certain compensation harmonic current is injected into the power supply buses, and meanwhile, the difference mode interference and the common mode interference on the power supply buses are removed, and the low-frequency interference conduction and radiated emission quantity of the long distance transmission cable of the power grid can be effectively controlled.

The invention discloses a multi-purpose portable automatic detecting instrument for soil moisture, air pressure, and temperature, which comprises a soil moisture content signal detection input conversion portion, air pressure signal detection input conversion portion, temperature signal detection input conversion portion, push-button portion, graph dot matrix mode liquid crystal display portion, high capacity nonvolatile storage portion, real time clock portion, power supply management portion, communication interface portion and microprocessor portion, wherein the sensor and the observing and control portion form a set of portable temperature and pressure detection and recording apparatus.The advantages of the apparatus by the invention are high measurement accuracy and low power consumption, it is suitable for the on-site data acquisition in various industrial and scientific research fields.

The invention relates to a sound wave transmitting device for depth measuring instrument, which belongs to the technical field of sonar measurement equipment for underwater survey using sound wave, and particularly relates to a high-power sound wave transmitting device for depth measuring instrument. The device mainly comprises a transmission pulse frequency dividing frequency, a transmission loop drive module, a transmission wave power main loop module, a protection module and an energy converter, wherein the transmission pulse frequency dividing module receives a transmission pulse signal from a depth measuring instrument control circuit, and transmits transmission pulse signals of positive and negative half cycles of transmission wave formed respectively after frequency division to left and right transmission loop drive modules; the left and right transmission loop drive modules drive each switch tube of full bridge circuit of the transmission wave power main loop module; the transmission wave power main loop module loads high voltage direct current to the energy converter through the full bridge circuit formed by four switch tubes to form transmission sound wave of the depth measuring instrument; and the protection module acquires a signal from the power main loop module, and a control signal is output when the circuit has exceptional situation such as short circuit and the like to stop all the transmissions so as to protect transmission circuits. Quality of sound wave transmission of the depth measuring instrument can be greatly improved by such high-power transmission circuit without transformer, and the device has wide application prospect.

The invention discloses a ventricular repolarization high-frequency wave double-limb electrode detecting device. An interface circuit is adopted to suppress influence of common mode current; a band-pass filter is adopted to remove noise of instruments; small-wave-range Wiener filtering is adopted, electromyographical interference is removed effectively, and finally extraction of ventricular repolarization high-frequency waves is realized; and the device can obtain original signals containing the ventricular repolarization high-frequency waves and interference signals from two wrists of a patient, after being amplified and realizing digital to analog conversion, the original signals are stored into a memory card via a micro-controller, then data in the memory card are read into a computer, and then ventricular repolarization high-frequency wave signals can be obtained via after the data are processed via software. The ventricular repolarization high-frequency wave double-limb electrode detecting device has the advantages of portability and low power consumption, and can realize long-term dynamic detection.

The invention provides a circuit for regulating and controlling an output power of a power supply, which comprises signal generating circuit, a photoelectric coupling circuit, a transformation switching circuit and a thyristor. The thyristor is connected between the power supply and a load. The signal generating circuit generates a first pulse signal having an adjustable duty ratio and provides the first pulse signal to the photoelectric coupling circuit. When the first pulse signal has a high electric level, the photoelectric coupling circuit is closed and the photoelectric coupling circuit outputs a sinusoidal signal. The sinusoidal signal is converted into a second pulse signal through the transformation switching circuit so as to control the on and off of the thyristor. When the second pulse signal has a high electric level, the thyristor is turned on and the power supply supplies a power to the load; and when second pulse signal has a low electric level, the thyristor is turned off and the power supply does not supply the power to the load. The circuit for regulating and controlling the output power of the power supply uses the photoelectric coupling circuit to isolate the signal generating circuit and the transformation switching circuit. The photoelectric coupling circuit can effectively inhibit common code interference, and the signal generating circuit regulates and controls the output power of the power supply in unit time by regulating the duty ratio of the first pulse signal.

The invention relates to a high-power high-accuracy power supply with continuously adjustable voltage. The power supply is characterized by consisting of an input smoothing reactor (1), a rectifier bridge (2), a pre-charge loop (3), a common mode suppression reactor (4), an input electrolytic capacitor and discharge device (5), an input voltage detection module VM1, a power unit group (6), an output electrolytic capacitor and discharge device (7) and an output voltage detection module VM2 which are connected in turn, wherein the input electrolytic capacitor and discharge device (5), the input voltage detection module VM1, the power unit group (6), the output electrolytic capacitor and discharge device (7) and the output voltage detection module VM2 are connected with a controller module (8) respectively. The power supply realizes continuously adjustable function of voltage, reduces device loss, improves system efficiency and reliability, has the characteristics of high system integration and processing speed and flexible control mode and can very conveniently adjust parameters such as a protection value and the like.

The invention discloses a tunnel magnetoresistive accelerometer closed-loop control circuit based on a feedback capacitance torquer. The closed-loop control circuit comprises a tunnel magnetoresistiveaccelerometer structure, a tunnel magnetoresistive sensor module, an instrument amplifier circuit, a demodulation filter circuit, a PID control circuit, a feedback force application circuit and an acceleration signal. The tunnel magnetoresistive accelerometer has the advantages of high sensitivity and good noise performance; the tunnel magnetoresistive sensor module adopts a push-pull bridge structure, and can increase detection sensitivity of the tunnel magnetoresistive sensor and suppress common-mode interference in the signal; meanwhile, the tunnel magnetoresistive sensor module adopts anAC modulation working mode and can eliminate interference of a magnetic field in the space; the PID control circuit is used to track error signals until the error signals disappear, and correction ofthe closed-loop system can be realized quickly; and feedback force correction is realized through a differential capacitance torquer, and an inertial mass block can be restrained near the central position, thereby realizing closed-loop control of the tunnel magnetoresistive accelerometer and increasing system stability.

The invention discloses a system and a method for testing alkali metal atom number density spatial distribution uniformity of an atom magnetometer. The system comprises a detection laser, a laser beam expanding system, a polarization element, a magnetic shielding system, an alkali metal atom gas chamber, a light beam contour camera, a beam splitter prism and the like which are sequentially arranged in a light advancing direction. The method is based on an optical absorption principle, light intensity attenuation of linear polarized light before and after passing through an alkali metal air chamber is tested by using a light beam profile camera with a pixel at a um level, a two-dimensional distribution matrix of atomic number density in space is calculated, and the uniformity of atomic number density distribution is analyzed by using a discrete coefficient. The system is simple to operate, easy to implement and extremely high in resolution ratio, direct measurement can be carried out on the basis of not changing the optical path of the atom magnetometer, the uniformity of the atomic number density in spatial distribution can be tested with high precision, the measurement sensitivity can be improved, and particularly the common-mode interference of a multi-channel differential magnetometer can be inhibited.

The invention discloses a train running part state monitoring multi-parameter sensor comprising an outer shell 1, a pedestal 2, a lead wire connecting head 3, an electric charge amplifier 4, a mass block 5, a vibration and impact sensitive device 6, a current-limiting resistor 7, a temperature sensitive device 8, a temperature-sensitive logic element 9 and a seal sheet 10. Four kinds of parameters that are vibration parameters, impact parameters, temperature parameters and temperature-sensitive logic state parameters of key components of a running part of a train can be monitored in a concentrated manner; strong electromagnetic interference in train running part state monitoring processes can be effectively inhibited; a problem that single end output sensors usually used in conventional train running part state monitoring processes are low in anti-interference capabilities can be overcome; misdiagnosis or missed diagnosis caused due to misfunctioning sensitive elements in the conventional train running part state monitoring processes can be prevented; application requirements for train running part operating state monitoring and fault diagnosis can be satisfied.

The invention relates to an inverter common-mode interference suppression circuit, which belongs to a circuit for suppressing the common-mode interference output between the direct current and alternating current sides of an inverter. The circuit can be widely applied to the inverter with high suppression requirements on common-mode current, such as transformer-free photovoltaic grid connected inverters. A realization method of the inverter common-mode interference suppression circuit is characterized in that two capacitors with the same capacity are connected in series between two electrodes of the alternating current output side, capacitors are connected between the direct current input end and the middle point of the capacitors, and in addition, a common-mode reactor is added in a proper position of the circuit. The inverter common-mode interference suppression circuit has the advantages that the suppression on the inverter circuit common-mode interference is realized at lower cost, the electromagnetic capacitive character of a system is improved, and in addition, the support is provided for realizing isolation-transformer-free inverters.

The invention provides a common-mode interference restraining circuit of an air conditioner. The common-mode interference restraining circuit comprises an indoor unit and an outdoor unit, wherein a power end of the indoor unit is connected with a power grid power supply through a first group power line; a grounding end of the indoor unit is connected with an earth wire of a power grid through a first grounding line; a power end of the outdoor unit is connected with the power end of the indoor unit through a second group power line; a grounding end of the outdoor unit is connected with the grounding end of the indoor unit through a second grounding line; and a first common-mode filer is arranged at the power end of the indoor unit in order to filter the common-mode interference which is generated by a frequency conversion system of the outdoor unit during working, is intensified by parasitic parameter resonance on the second group power line and the second grounding line. An inductor isconnected to an equivalent position of the indoor unit, and a capacitor is connected in parallel to the position in order to prevent common-mode current from flowing into the power grid, so that theattenuation of EMI is enhanced, and EMI interference is restrained. Meanwhile, minimalization for an electric control board of the outdoor unit can be realized, and the cost is lowered.

The invention discloses an electric automobile smooth capacitor, comprising a main capacitor set, and two leading-out terminals respectively connected to two poles of the main capacitor set; two Y capacitors which are in parallel connection with the main capacitor set after series connection are arranged between the two leading-out terminals; a neutral point leading-out ground terminal is arranged between the two Y capacitors. The main capacitor set is composed of a plurality of capacitor element in parallel connection. The electric automobile smooth capacitor can restrain common mode interference, and has the characteristics of smaller ESR and ESL, and good weather fastness.

The invention discloses a common-mode interference suppression device, a variable-frequency electric appliance and a common-mode interference suppression method thereof. The common-mode interference suppression device is used for the variable-frequency electric appliance. The variable-frequency electric appliance comprises a compressor and a draught fan motor. The common-mode interference suppression device comprises a magnetic coupling assembly; the magnetic coupling assembly is arranged between the compressor feed line and compressor inverter bridge of the compressor as well as between the draught fan feed line and draught fan inverter bridge of the draught fan motor and is used for generating a magnetic coupling effect, so that the common-mode loop impedance of the compressor feed lineand the draught fan feed line is improved, and therefore, the common-mode interference of the compressor and the draught fan motor is suppressed. With the common-mode interference suppression device,the variable-frequency electric appliance and the common-mode interference suppression method provided by the technical schemes of the invention adopted, the problem of EMI interference of a draught fan motor with a variable frequency or chopping control function can be solved, and the EMI interference can be suppressed.