40results about How to "Reduce common mode current" patented technology

A system for converting at least one electrical input direct current into an electrical output alternating current comprising M phases and supplied to M output terminals includes N polyphase inverters, connected in parallel, each converting the input direct current into an intermediate alternating current comprising M phases and supplied to M intermediate terminals; N×M first electromagnetic coupling coils, each being connected to a respective intermediate terminal; N×M magnetic cores, each first coil being wound around a respective core.This system comprises N×M second electromagnetic coupling coils, each being connected to a respective first coil and wound around a distinct core from that of the respective first coil. The first and second coils of a same core correspond to a single phase, and generate respective common mode fluxes of opposite directions. Each output terminal is connected to the M second coils of a single phase.

The invention discloses a common-mode voltage suppression method for a non-isolated T-shaped tri-level photovoltaic grid-connected inverter. The method comprises steps as follows: voltage of an upper capacitor C1 of a direct-current bus and voltage of a lower capacitor C2 of the direct-current bus are collected in real time to obtain an absolute value dUdc of voltage difference of the upper capacitor C1 and the lower capacitor C2 of the direct-current bus; whether dUdc is larger than dUref and whether Uc1 is larger than Uc2 are judged, so that a large and medium zero vector synthesis method, a large, medium and small vector synthesis method or a large and large zero vector synthesis method is selected and utilized for modulating the non-isolated T-shaped tri-level photovoltaic grid-connected inverter. The three vector synthesis methods are adopted to modulate the non-isolated T-shaped tri-level photovoltaic grid-connected inverter, so that the midpoint potential of the direct-current side of the tri-level inverter can be balanced, the amplitude and frequency of common-mode voltage change can be suppressed, accordingly, common-mode current of the non-isolated T-shaped tri-level photovoltaic grid-connected inverter is suppressed, and the efficiency, the size, the weight and the cost of a system are optimized.

An apparatus is provided for heating a hydrocarbon resource in a subterranean formation having a wellbore extending therein. The apparatus includes a radio frequency (RF) antenna configured to be positioned within the wellbore, a transmission line configured to be positioned in the wellbore and coupled to the RF antenna, and an RF source configured to be coupled to the transmission line. The apparatus also includes a balun configured to be coupled to the transmission line adjacent the RF antenna within the wellbore. The balun comprises a body defining a liquid chamber configured to receive a quantity of dielectric liquid therein.

The invention discloses a radiation source screening and positioning method based on STFT time frequency analysis. According to the method, an independent component analysis ICA algorithm is in combination with STFT, and a systematic, comprehensive, standardized radiated EMI analysis and diagnosis method is proposed. Firstly, radiation noise of EUT is separated through an ICA algorithm, and multiple radiation noise sources are screened out; secondly, short-time rapid Fourier transform and time frequency analysis on exceeding-standard frequency ranges of the overall radiation noise are carried out, and signal characteristics causing exceeding-standard radiation are extracted; lastly, the extracted signal characteristics and the multiple radiation noise sources screened out by the ICA are contrasted, positioning diagnosis on the noise sources causing exceeding-standard radiation noise is carried out, and pertinent rectification inhibition measures are adopted. The method can rapidly and effectively inhibit exceeding-standard noise of equipment through searching the corresponding device causing exceeding-standard radiation.

The invention discloses a non-isolated soft switching DC-DC converter with low input current ripple and high output voltage gain, which is composed of a high-gain boosted circuit and a soft switchingauxiliary circuit, wherein the high-gain boosted circuit comprises a first boosted circuit and a second boosted circuit, the first boosted circuit and the second boosted circuit are each composed of amain inductor, a capacitor, a diode and a main switching tube, the input ends of the first boosted circuit and the second boosted circuit are connected in parallel by adopting a two-phase staggered structure, the output ends of the first boosted circuit and the second boosted circuit are connected in series in a two-phase mode through a switched capacitor structure, the soft switching auxiliary circuit is composed of an auxiliary inductor and an auxiliary switching tube, the soft switching auxiliary circuit is connected with one phase in parallel, and zero-voltage conduction of the main switching tubes of the two boosted circuits is achieved; and the inductors of the first boosted circuit and the second boosted circuit and the auxiliary inductor are integrated in one magnetic core.

A mechanism for reducing common-mode current in a system including a first subsystem and an isolated subsystem. The isolated subsystem may receive the common-mode current from the first subsystem via an isolation mechanism. The isolation mechanism (e.g., a transformer) may isolate the isolated subsystem from the first subsystem by blocking DC signals. The first subsystem may include a pulse generation unit and compensation circuitry. The pulse generation unit may provide a first pulse and a second pulse to the compensation circuitry. The phase and duty cycle of the pulses may be varied based on measured characteristics of the isolation mechanism. The compensation circuitry may generate a cancellation signal based on the first and second pulses. Furthermore, the compensation circuitry may provide the cancellation signal to a ground plane of the isolated subsystem to reduce the common-mode current received at the isolation subsystem.

A transformer capable of suppressing common mode current and a power converter thereof are provided. The transformer comprises a primary winding, a secondary winding, a magnet core and a shielding winding layer. The shielding winding layer has a first shielding winding and a second shielding winding. A voltage jump direction of the first shielding winding is constantly opposite to that of the second shielding winding. The shielding winding layer is coupled to a static terminal coupled with the primary winding or the secondary winding.

An apparatus is provided for heating a hydrocarbon resource in a subterranean formation having a wellbore extending therein. The apparatus includes a radio frequency (RF) antenna configured to be positioned within the wellbore, a transmission line configured to be positioned in the wellbore and coupled to the RF antenna, and an RF source configured to be coupled to the transmission line. The apparatus also includes a balun configured to be coupled to the transmission line adjacent the RF antenna within the wellbore. The balun comprises a body defining a liquid chamber configured to receive a quantity of dielectric liquid therein.

An electronic device comprising: a wiring substrate having a first power-supply wiring to which a first power-supply potential is applied and a second power-supply wiring to which a second power-supply potential lower than the first power-supply potential is applied; a microcomputer having first and second power-supply terminals in which the first power-supply terminal is connected to the first power-supply wiring and the second power-supply terminal is connected to the second power-supply wiring; and a connector connected to the first and second power-supply wirings, wherein an inductor element for correcting an impedance error of the first and second wirings is connected in series to either one of the first and second power-supply wirings. According to such configuration, unnecessary electromagnetic radiation posed by a common current can be suppressed.

The invention relates to a topological structure of a photovoltaic grid-connected single-phase inverter employing a fly-wheel neutral point potential. The topological structure of the photovoltaic grid-connected single-phase inverter comprises a photovoltaic array, a clamping capacitor bank, a single-phase full-bridge inverter, a filter circuit, a power grid and a two-way clamping circuit unit, wherein the photovoltaic array, the clamping capacitor bank, the single-phase full-bridge inverter, the filter circuit and the power grid are sequentially connected with one another; the two-way clamping circuit unit comprises a positive clamping circuit unit and a negative clamping circuit unit; and the positive clamping circuit unit and the negative clamping circuit unit are connected with the clamping capacitor bank and the filter circuit. Compared with the prior art, the topological structure of the photovoltaic grid-connected single-phase inverter has the advantages of constant common-mode voltage, good common-mode characteristic and the like.

A radio frequency (RF) antenna assembly configured to be positioned within a wellbore in a subterranean formation for hydrocarbon resource recovery may include an RF transmission line and an RF antenna coupled to the RF transmission line. The RF antenna assembly may also include an adjustable balun that may include a tubular balun housing surrounding the RF transmission line and defining a space therebetween. The adjustable balun may further include an adjustable shorting body slidably movable within the space and contacting the tubular balun housing and the RF transmission line at an adjustable shorting position.

The invention discloses a switching power supply, a flyback converter and a transformer. Primary windings are divided into a first primary winding and a second primary winding; a power switch is connected between the first primary winding and the second primary winding; a secondary winding is arranged between the first primary winding and the second primary winding in the magnetic core radial direction in the transformer; current between the first primary winding and the secondary winding and current between the second primary winding and the secondary winding have opposite directions; and thus common-mode conduction current between the primary winding and the secondary winding can be reduced. Thus, on the premise of not using a shielding winding and a Y capacitor, EMI optimization can be realized, and while the number of devices is reduced, the filling factor and the coupling efficiency of the transformer are added.

The invention discloses a wireless power transmission device. According to the wireless power transmission device, a primary side compensation capacitor (or a secondary side compensation capacitor) is configured to comprise N sub-compensation capacitors which are evenly connected in a power transmitting coil (or a power receiving coil), so as to divide the power transmitting coil (or the power receiving coil) into N equal parts accordingly. By adopting the connection structure of the distributed capacitors, a voltage of each section of the power transmitting coil (or the power receiving coil) can be reduced, thus a common mode current of the power transmitting coil to the ground or a circular current of the power receiving coil to metal is reduced, and the resonant frequencies of the coil and the total compensation capacitors of a primary side or a secondary side are identical with the operating frequency of the system, thereby ensuring the highest energy transmission efficiency.

The invention relates to a single-phase three-level bridgeless PFC (power factor correction) rectifier, comprising a crossbar filter network, a power electronic switch network, direct-current capacitor C1 and direct-current capacitor C2; a first input end of the crossbar filter network is connected with a first end of power supply voltage vs, a second input end of the crossbar filter network is connected with a second end of the power supply voltage vs, a first output end of the crossbar filter network is connected with a first input end of the power electronic switch network, and a second output end of the crossbar filter network is connected with a second input end of the power electronic switch network. Since the crossbar filter network is introduced to an existing three-level bridgeless PFC filter, the advantages of the original three-level bridgeless PFC filter can be retained, and common mode current of the rectifier can be greatly decreased at the premise of not increasing leakcurrent and safety risk; the single-phase three-level bridgeless PFC rectifier is suitable for use in places having strict limitations on leak current and common mode noise.

The invention discloses an FPGA-based optical interface 1+1 protection isolated multi-service Ethernet optical transceiver, comprising an optical signal transceiving circuit, a power supply circuit and a signal enhancement circuit, wherein the signal enhancement circuit comprises a first coil and a second coil, a capacitor C1 is coupled between a node at which the first coil and the second coil are connected and the ground, the secondary of an input transformer is also coupled with a common mode inductor, the arranged common mode inductor can suppress the outward radiation of electromagnetic waves during high-speed signal transmission from interfering with the signal transmission of adjacent equipment, the arranged capacitor C1 serves as a tap capacitor and is combined with the power supply circuit to provide a function of a DC bias voltage or a power source, the common mode current and common mode voltage on a cable can also be reduced by providing a low-impedance reflux path of common mode noises on a differential line, and thus the arranged enhancement circuit can not only enhance optical signals and extend the transmission distance, but also isolate the two ends of the input transformer and further prevent lightning strikes.

The invention belongs to the field of power electronics, and particularly relates to a modulation method for reducing common-mode voltage of a three-phase pulse-width modulation (PWM) converter. The modulation method is characterized in that three nonadjacent nonzero basic space vectors are used for synthesizing a target vector, and is further characterized in that two comparison value counting modules are adopted to generate control pulse, and the counting modules are different in counting mode. Counting modes of the comparison value counting modules used for generation of out-phase bridge arm control pulse in the same sector of voltage commands are different, and in the different sectors, the counting modes of the comparison value counting modules used by the same-phrase bridge arm are also different. The modulation method has a good common-mode voltage restraining effect, the common-mode voltage maximum peak is one-sixth of direct current bus voltage, and therefore common-mode currents can be effectively reduced when the modulation method is applied to fields of photovoltaic power stations, motor drive and charging stations.

The invention discloses a driving method and device of a switching tube and an inverter, and relates to the technical field of inverters, the driving method of the switching tube is applied to the inverter, and the method comprises the following steps: obtaining the current of each phase of the inverter, and determining the common-mode current of the inverter according to the average value of each current. A common-mode voltage suppression component of the inverter is determined according to the common-mode current and first impedance, the first impedance comprises at least one of a first resistor, a first inductor and a first capacitor, and the common-mode voltage suppression component is used for suppressing the common-mode current. And driving the switching tube according to the common-mode voltage suppression component. Through the above mode, the common-mode current can be suppressed in the working process of the inverter, and the quality of the inverter inductive current waveform is improved.

The present invention belongs to the technical field of power electronics and provides a common mode current suppression circuit of a motor drive system for solving the interference of high frequency interference generated by a controllable rectifier and an inverter on a motor drive system and surrounding devices. The present invention includes three LC filter circuits, a transmission device and a micro control unit; the three LC filter circuits are respectively connected in series between the inverter output end and the motor input end, each LC filter circuit is formed by an adjustable inductor and a non-polar capacitor connected in series; the micro control unit controls the transmission device according to the frequency of the modulated wave signal output by the inverter; and the transmission device controls the inductance value of the adjustable inductor in each LC filter circuit separately by a sliding sheet, so that the driving current of the motor reaches the resonance in the LC filter circuit . The common mode current suppression circuit effectively suppresses the total conduction path of the common mode current to realize the common mode current suppression of the motor drive system, and ensures that the driving signal of the motor cannot be attenuated.

the invention provides a spatial vector modulation method of an indirect matrix converter. The method comprises the following steps of determining a first duty cycle of a zero vector of an inversion stage, selecting a plurality of turning periods in a modulation period, wherein the total time length of the plurality of turning periods is the product of the first duty ratio and the modulation period, taking the starting time of each turning period as the modulation time for the switching states of the rectifying stage and the inversion stage in each turning period, adjusting all the switches ofthe rectifying stage to be disconnected at the starting moment of each turning period, remaining all the switching states of the inversion stage unchanged; namely, disconnecting all the switches of the rectification stage to realize the introduction of a zero vector into the inversion stage, in the modulation process of the indirect matrix converter in a time period when a zero vector originallyneeds to be led into to the inversion stage. The switch state at the initial moments of the time periods at the inversion stage does not need to be adjusted, so that the frequency of the action of theswitch of the inversion stage is reduced on the basis of reducing the common mode current. The loss of the system is reduced.

The invention discloses a switching power supply, a flyback converter and a transformer. By dividing the primary winding into two parts, the first primary winding and the second primary winding, the power switch is connected to the first primary winding and the second primary winding. Between the two primary windings, at the same time, in the transformer, the secondary winding is arranged between the first primary winding and the second primary winding in the radial direction of the magnetic core, so that the first primary winding and the secondary winding The direction of the current between the second primary winding and the secondary winding is opposite to that of the current, thereby reducing the common mode conduction current between the primary and secondary windings. Therefore, the optimization of EMI can be realized without using the shielding winding and the Y capacitor, and the fill factor and coupling efficiency of the transformer can be increased while reducing the number of components.

The invention discloses an electric energy emission structure and a wireless charging device employing the same. By connecting a common-mode current suppression circuit between an inversion circuit and an emission coil, a common-mode current between the emission coil and the ground can be reduced very well, the conduction interference of electromagnetic compatibility (EMC) is reduced, meanwhile, a high-frequency common-mode current generated by a high-frequency component of an AC voltage output from the inversion circuit on the emission coil also can be reduced, and the radiation interference influence of the high-frequency AC component on the EMC of a system is reduced.

The invention provides a space vector modulation method of an indirect matrix converter, comprising: determining the first duty ratio of the zero vector of the inverter stage, selecting several switching periods in the modulation period, and the total duration of the several switching periods is the first duty cycle The product of the empty ratio and the modulation cycle, the initial moment of each switching period is used as the modulation moment for the switch state of the rectifier stage and the inverter stage in each switching period, at the beginning of each switching period, the rectification stage All the switches of the inverter are adjusted to be off, and the state of all the switches of the inverter stage is kept unchanged; that is, in the modulation process of the indirect matrix converter, the rectifier stage All the switches of the inverter are turned off to realize the introduction of zero vector to the inverter stage, and the inverter stage does not need to adjust the switch state at the beginning of these periods, thereby reducing the switch of the inverter stage on the basis of reducing the common mode current. The number of actions reduces the loss of the system.

A radio frequency (RF) antenna assembly configured to be positioned within a wellbore in a subterranean formation for hydrocarbon resource recovery may include an RF transmission line and an RF antenna coupled to the RF transmission line. The RF antenna assembly may also include an adjustable balun that may include a tubular balun housing surrounding the RF transmission line and defining a space therebetween. The adjustable balun may further include an adjustable shorting body slidably movable within the space and contacting the tubular balun housing and the RF transmission line at an adjustable shorting position.

The invention discloses a common-mode voltage suppression method of a non-isolated T-type three-level photovoltaic grid-connected inverter, which collects the voltage of the capacitor C1 on the DC bus and the voltage of the capacitor C2 under the DC bus in real time, and obtains the voltage of the capacitor C1 on the DC bus and the voltage of the DC bus. The absolute value of the voltage difference dUdc of the capacitor C2 under the bus bar, by judging whether dUdc>dUref is true, and judging whether it is true, choose to use the large and medium zero vector synthesis method or the large, medium and small vector synthesis method or the large and small zero vector synthesis method for non-isolated T-type Three-level photovoltaic grid-connected inverter for modulation. The invention adopts three kinds of vector synthesis methods to modulate the non-isolated T-type three-level photovoltaic grid-connected inverter, which can not only balance the midpoint potential of the DC side of the three-level inverter, but also suppress the amplitude of the common-mode voltage change and frequency, thereby suppressing the common-mode current of the non-isolated T-type three-level photovoltaic grid-connected inverter, and optimizing the efficiency, volume, weight, and cost of the system.

A three-phase converter, which is used to connect between a DC system and an AC system for mutual conversion of DC and AC. The three-phase converter includes a switch network, a three-phase filter connected to the switch network, and a three-phase filter connected to the switch network. The sampling unit, the control unit connected to the sampling unit, the active damping unit connected to the control unit and the sampling unit, and the modulation unit connected between the active damping unit and the switch network. The sampling unit is used to obtain the three-phase current in the three-phase filter, and send the three-phase current to the active damping unit. The active damping unit is used to obtain a new three-phase modulation wave according to the three-phase current, and transmit the new three-phase modulation wave to the modulation unit. The modulation unit is used for modulating the new three-phase modulation wave as a driving signal of the switch network to drive the switch network to work.