81 results about "Conducted electromagnetic interference" patented technology

An actively controlled regenerative snubber configuration for use in unipolar brushless direct current motors comprises a first inductor, a first switch and a capacitor, all of which are connected in series to a positive voltage supply and in parallel with a second inductor and a second switch. The regenerative snubber is used to maintain constant voltage across the switches to prevent braking of the motor through conduction of motor back EMF and to return excess energy stored in the motor phase coils to the positive voltage supply. The return of energy to the positive rail is done in a manner so as to minimize conducted electromagnetic interference at the power leads.

The invention relates to the field of electromagnetic compatibility, in particular to a system and a method for modeling printed circuit board level conducted electromagnetic interference. Conducted interference of a power wire port of a certain control circuit board is quantitatively analyzed by extraction through a circuit model and modular modeling. Interference noise sources, equivalent resistance R, inductance L, capacitance C, conductance G parameters and internal logic circuits of devices are acquired by respectively calculating and equalizing circuits, main interference chips, power modules and the like on the circuit board, modular package is performed, so that an equivalent circuit model of the whole power system is built, and conducted interference waveforms and quantitative spectra of points on a power wire can be obtained by circuit simulation. Conducted electromagnetic interference frequency and amplitude of key circuits on the printed circuit board can be quantitatively analyzed at a pre-design phase, portions with poor electromagnetic compatibility are found and optimized, the electromagnetic interference degree of the whole circuit board is reduced, and research and development cycle and cost can be reduced.

The invention discloses a radio frequency current probe characteristic calibrating method based on electromagnetic compatibility analysis and application and belongs to the field of electromagnetic compatibility analysis and application and electromagnetic interference noise measurement. According to a frequency section needing to be measured, in the method, the transfer impedance of a current probe is tested in a time domain by utilizing a dual-trace oscilloscope and then tested in a frequency domain by utilizing a vector network analyzer and adopting a scattering parameter method; and finally, a measurement conversion coefficient of the current probe can be more accurately obtained. The method has simple operation and accurate test, enables a result of electromagnetic interference noisemeasured by the current probe to be more accurate, and provides a theoretical basis for conducting the electromagnetic interference noise.

The invention discloses a soft separation method of conducted electromagnetic interference noise based on a blind signal processing technology, belonging to the field of conducted electromagnetic interference noise inhibition. The method comprises the following steps of: carrying out probe frequency spectrum estimation and compensation on two current probes; simultaneously measuring electromagnetic interference noise time domain signals on a live wire and a middle wire of an electronic system by the two current probes and a double-trace oscilloscope; carrying out blind separation on electromagnetic interference noise by utilizing a Fast ICA (Independent Component Analysis) algorithm in a blind signal processing method to obtain a signal source vector estimation value; and finally, judging the property of separation signals based on the maximum cross correlation coefficient of blind separation signals and common mode or differential mode reference signals. The invention overcomes the defects of using a radiofrequency transformer or a power divider to carry out hard separation on common mode noise and differential mode noise, has the advantages of high separation accuracy and favorable practicability, and lowers the cost.

The invention relates to a conduction electromagnetic interference experimental platform for an electric automobile motor driving system. The conduction electromagnetic interference experimental platform comprises an electric network, a power supply, a positive electrode artificial power supply network, a negative electrode artificial power supply network, a motor controller, a motor, load equipment, the ground, a low-relative-dielectric-constant support object, a grounding flat plate, a test desk, a shielding chamber or a dark chamber, test equipment, motor control signals, a motor support frame and a load equipment support frame. The conduction electromagnetic interference experimental platform has the advantages that the conduction electromagnetic interference experimental platform for the electric automobile motor driving system is built, in addition, the motor is loaded for testing conduction voltage and conduction current generated by a system under different work conditions, and an effective test platform and test method is provided for studying the electromagnetic interference generating mechanism of the motor driving system and inhibiting the electromagnetic interference generated by the motor driving system.

The invention discloses a passive suppression method for the conducted electromagnetic interface of a PWM (power width modulation) power converter, belongs to the field of motor drive control and electromagnetic compatibility of integrated motor systems, and aims to solve the problems of low reliability, increase of a failure rate and incapability of reaching an electromagnetic compatibility standard of the conventional motor driving system under the influence of electromagnetic interface. An alternating current power supply, a rectifier, two direct current bus capacitors, an inverter, a long cable, a motor, a first filter and a second filter are involved, wherein the alternating current power supply is connected with the rectifier; the output end of the rectifier is connected with the two direct current bus capacitors; the other ends of the direct current bus capacitors are connected with the inverter; the output of the inverter is connected to the motor through the long cable; the input end of the first filter is connected to the inverter, a part of the output end of the first filter is connected to the motor, and another terminal is led from the output end of the first filter to be connected to a direct current bus clamping neutral point; the input end of the second filter is connected to the rectifier, a part of the output end of the second filter is connected to a power grid, and another terminal is led from the output end of the second filter to be connected to a neutral point of the motor. The method is applied to a PWM motor driving device.

This invention discloses a broad band high attenuation common mode conductive electromagnetic interference parallel mixed filter including a passive common mode filter inductor LCM, the input end of which is serial to the output of the HF current inductor LCT to make up of an active filter and a passive filter, the passive common mode filter inductor is serial to a noise source device to filter the HF electromagnetic noise effectively and correct the source impedance property of the device, in which, the output of the operational amplifier is parallel to the resistor by two high voltage ceramic condensers to be connected to the input of a small passive common mode inductor and works at the open loop state, the input of which is serial to the network side of the device by a HF current mutual inductor.

The invention relates to a method for estimating electromagnetic interference of a power electronic conversion system based on a power transmission line. The method comprises the steps of enabling thepower transmission line between a power electronic conversion device and a power system to be equivalent to a transmission circuit; establishing a physical structure of wideband equivalent resistance-inductance steplike topology of the power transmission line; accurately identifying and optimizing wideband key parasitic parameters of the resistance-inductance steplike topology of the transmissionline based on a vector fitting iteration strategy; and substituting the calculated key parasitic parameter values of the resistance-inductance steplike topology into the transmission circuit and estimating a difference mode/common mode conducted electromagnetic interference level of the power electronic conversion system. According to the method, the numerical equivalence is performed on the basis of a resistance-inductance steplike topology theory, so that the frequency change transmission characteristic of inherent parameters of a cable is represented, accurate approximation and stable convergence of a prediction model are achieved, and an effective theoretical basis is provided for achieving accurate identification of wideband parasitic parameters of the model and EMC design of the power electronic conversion system.

The invention discloses a high attenuation microminiaturte common mode transmission electromagnetic interference active filter, which includes ring high-frequency current-transformer, wherein three windings twine round the mutual-inductor; the coiling directions of three windings are the same; two windings connect the alternating current power lead-in end; another end connects the carry-in terminal of operational amplifier; the export of operational amplifier feedbacks signal to noise source device by two high-pressure capacitances and electric resistances. The filter has simple and reasonable structure, which has strong noise attenuation ability and good low-frequency filtering feature.

The invention relates to a transmitting device for transmission through space, using electromagnetic waves of the infrared and/or visible and/or ultraviolet bands produced by one or several diodes producing electroluminescent light.

The device is connected by its input terminals (1) to an a.c. energy distribution system. A mains filter (2) reduces the conducted electromagnetic disturbances produced by the power circuits comprising a rectifier (3), a power-factor-correction circuit (4), an auxiliary power supply (5) and a DC-to-DC converter (8). The output of the DC-to-DC converter (8) is connected to several high power light-emitting diodes connected in series (9). A receiving set for transmission via power distribution lines (6) delivers demodulated signals applied to the control circuitry (7) which provides the current command of the DC-to-DC converter (8) and the modulated current applied to the light-emitting diodes (9) through the modulation transformer (10), as a function of the demodulated signals and of the temperature which is measured by a temperature sensor (11). The produced light is modulated as a function of the demodulated signals.

The invention discloses a common mode filter for inhibiting conducted electromagnetic interference. At least three live wire jacks are connected in series through leads to form a first live wire jack row; at least three live wire jacks are connected in series through leads to form a second live wire jack row; a first inductor is arranged between the live wire jack on the first live wire jack row load side and the live wire jack on the second live wire jack row power grid side; at least three neutral wire jacks are connected in series through leads to form a first neutral wire jack row; at least three neutral wire jacks are connected in series through leads to form a second neutral wire jack row; a second inductor is arranged between the live wire jack on the first neutral wire jack row load side and the live wire jack on the second neutral wire jack row power grid side; and at least three ground wire jacks are connected in series through leads to form a ground wire jack row. Aiming at conducted electromagnetic interference common mode noise caused by an unknown noise source, the common mode filter avoids the problems of circuit board damage caused by repeatedly welding a circuit board, poor filter effect and the like.

The invention relates to a modulation method and device for reducing the ultra-high-order harmonic amplitude at the switching frequency of a converter. The modulation method comprises the steps: generating a pseudo-random sequence; calculating the upper limit frequency and the lower limit frequency of the random switching frequency PWM; and generating a carrier signal and a modulation signal, andcarrying out random switching frequency PWM modulation. The random switching frequency PWM modulation can effectively reduce the amplitude of ultra-high-order harmonics at the switching frequency of the converter, and enables the ultra-high-order harmonics to be uniformly distributed in a wider frequency range, thereby inhibiting the conducted electromagnetic interference in a switching circuit, and improving the electromagnetic compatibility of a system.

The invention belongs to the research field of power electron and electromagnetic interference and discloses a common mode/differential mode noise discrimination network. The network comprises two line transformators which are in parallel connection, the driving point impedances of the two line transformators are both100 omegas so that Zin1=Zin2=50 omega is precisely guaranteed and the network can better play the role of the frequency bandwidth of the line transformators; meanwhile, a compensation capacitor is added to ensure that the driving point impedances of the common mode/differential mode noise discrimination network are kept within 50 omegas. The common mode/differential mode noise discrimination network can reach impedance matching of separate meshes, realizes that the network always keeps the characteristic impedance of 50 omegas in the 30 MHz broad band, and can be applied to various common mode/differential mode separations which can conduct electromagnetic noise.

The invention provides a near field probe used for detecting electromagnetic interference radiation performance. The near field probe used for detecting electromagnetic interference radiation performance comprises an electric field/magnetic field sensor, a photoelectricity conversion module and optical fibers, the electric field/magnetic field sensor comprises a three-hole optical fiber inserting core, three electric light/magnetic light crystals with different polarization directions, and a protective sleeve, three optical fibers drawn from the photoelectricity conversion module are respectively connected with the three electric light/magnetic light crystals with different polarization directions through the three-hole optical fiber inserting core, and the photoelectricity conversion module comprises a laser device, a 1*3 optical fiber beam splitter, three photoelectricity detectors, three optical fiber circulators, three optical polarization controllers and three radiofrequency output interfaces. The invention further provides an application method of the near field probe used for detecting electromagnetic interference radiation performance. The near field probe used for detecting electromagnetic interference radiation performance and the application method of the near field probe used for detecting electromagnetic interference radiation performance have the advantages that a circumscribed light source and the photoelectricity detector are unnecessary, a traditional radiofrequency output interface is used for outputting, measuring and application methods are compatible with an existing electromagnetic interference measuring system, and an electricity probe can be directly replaced to conduct electromagnetic interference test.

The invention provides a physiological electric signal detection device based on a flexible non-contact electrode. The physiological electric signal detection device comprises the flexible non-contactelectrode, a shielding line and a signal acquisition module, wherein the signal acquisition module comprises an impedance matching unit, an anti-aliasing filter unit and an analog-to-digital conversion unit; the flexible non-contact electrode is used for detecting potential change of human body surface through a coupling capacitance which is formed by the flexible non-contact electrode and humanbody skin; the shielding line is used for transmitting a potential change signal to an input end of the impedance matching unit and for conducting electromagnetic interference shielding on the potential change signal in a transmitting process; the impedance matching unit is used for conducting signal amplifying processing on the potential change signal; the anti-aliasing filter unit is used for conducting filtering processing on the amplified potential change signal; and the analog-to-digital conversion unit is used for conducting analog-to-digital conversion processing on the amplified and filtered potential change signal, so that a physiological electric signal of human body is obtained. The detection device provided by the invention has the advantages of being comfortable to wear, goodin shielding performance, strong in anti-interference performance, simple in circuit structure, high in precision and low in cost.

The invention relates to a conduction electromagnetic interference simulation system for an alternating-current motor inverter power circuit of an electric car. The system comprises a cable model simulation module, an inverter power circuit simulation module and a power circuit signal acquisition module. The system is mainly used for analyzing the electric car motor drive system conduction electromagnetic interference production mechanism and propagation path. A cable model simulation module is established under electromagnetic compatibility cable modeling and simulation software, an inverter power circuit simulation module is established under electromagnetic compatibility high-frequency circuit modeling and simulation software, and a power circuit control signal acquisition module is established under mathematical simulation software. During simulation, the power circuit control signal acquisition module inputs control signals to the inverter power circuit simulation module to control the operation of the inverter, and a voltage monitoring module and a current monitoring module of the inverter power circuit simulation module are used for acquiring the power circuit voltage and current.

The invention discloses a single-channel conduction electromagnetic interference noise separation method, using continuous wavelet transform and FastICA blind source separation EMI noise difference common-mode separation strategy, the implementation steps include: A, using CWT for L-line or N-line observation signals Implement virtual channel expansion; B. Use the improved FastICA algorithm to implement blind source separation for the extended signal to obtain differential common-mode noise separation signals; C. Evaluate the separation ability of differential common-mode noise signals and perform amplitude correction. Although the separation performance of the method is lower than that of the dual channel, it only uses half of the observation information, overcomes the dual channel synchronous measurement error, and saves economic costs, and has potential application value in the field of industrial EMI noise difference common mode separation.

The invention discloses an electromagnetic interference monitoring and positioning method. Space radiation electromagnetic interference and cable conduction electromagnetic interference are respectively carried out by utilizing a group of detection antennas and cable calipers, wavelet denoising, template matching analysis and other technologies are fused, monitoring and rapid positioning of electromagnetic interference occurring in the assembling and integrating process of a system electronic system are achieved, and theoretical, method and technical supports are provided for effectively improving the electromagnetic environment adaptability of the development cycle of the electronic system. The method can be used for providing an online diagnosis method and technical support for electromagnetic interference occurring in the integrated debugging process of the electronic system, the diagnosis and positioning efficiency of the electromagnetic interference in the integrated debugging process of the electronic system can be greatly improved, the electromagnetic environment adaptability of the electronic system is effectively improved, and an electromagnetic interference monitoring andpositioning flow chart is shown in Figure 1.

The invention discloses a conducted electromagnetic interference noise source identification method based on a voltage parameter test ICA (independent component analysis) algorithm. The method comprises the following specific steps: firstly, an artificial mains network is adopted to extract the noise voltage signal of tested equipment; secondly, independent component decomposition is performed on the obtained noise voltage signal according to the ICA algorithm, so that the waveform characteristic results of the noise voltage signal is obtained; finally, contrastive analysis is performed on the waveform characteristic results of the noise voltage signal and characteristics of signals generated by each electron device in the tested equipment to determine the specific electron device generating the noise voltage signal, and finally, the conducted electromagnetic interference noise source is determined. The conducted electromagnetic interference noise source identification method accurately and rapidly solves the problem of identification of the conducted noise source by taking the electron device as a center, is simple and high in efficiency and systematized; the noise signal is effectively isolated on the basis of ICA algorithm, so that the electron device generating the conducted noise signal can be judged more accurately, and electromagnetic interference is reduced more purposefully.