865 results about "Ac current" patented technology

A charging bench includes three coils that partially overlap, in superposed planes. An electrical feed makes it possible to supply the coils with an AC current from the mains. A portable device to be charged is placed on the upper side of this charging bench. This device includes a winding intended to receive the electrical charging, and a ferrite protective screen. One of the coils (Bb) is selected to emit the magnetic charging flux toward the mobile phone. The selection is carried out via the emission of a series of pulses by at least one of the coils and comparison of return signals with a reference threshold. This comparison also enables one of the other coils (Ba, Bc) to be selected or both of these other two coils (Ba, Bc) to be used to receive a flux for communicating information originating from the portable device to be charged.

The invention discloses an LLC-DCDC fault protection method and device based on resonance current and pulse integration. The method comprises the following steps that an alternating current signal on an LLC converter resonance inductor is collected in real time through a resonance inductor current sampling circuit; inputting the current signal into a hardware comparator module, comparing the current signal with a preset current threshold value, and outputting a pulse signal; inputting the pulse signal into a pulse integral module for integral processing, and outputting an integral voltage signal; the CPU control unit receives a pulse signal output by the hardware comparator and an integral voltage signal output by the integral module in real time, and judges whether a fault occurs or not according to preset logic; and if the fault is judged, the driving signal of the primary inverter bridge of the LLC converter is cut off through the driving cut-off module.

A marine AC generator system includes a marine generator driven by an internal combustion engine and configured to generate an AC current and a rectifier configured to rectify the AC current to provide a DC current. At least one battery is configured to receive and be charged by the DC current. A battery powered inverter is configured to be powered by the at least one battery and to generate a variable current output frequency such that an AC electrical power is provided to a load when the marine generator is not running.

The invention discloses a current sensing measurement device and method, a storage medium and electronic equipment, and the device comprises an AC detection module which is used for sensing an AC current and outputting an AC current analog signal; the direct-current compensation module is used for acquiring magnetic induction intensity generated by a direct-current component of the detected current and outputting a differential voltage analog signal; the compensation module is used for outputting compensation current which is equal to the direct-current component in size but opposite to the direct-current component in direction based on the compensation control signal output by the signal processing module so as to offset direct-current magnetic flux generated by the direct-current component; and the signal processing module is used for calculating a direct current component, a compensation current and an alternating current based on the alternating current analog signal and the differential voltage analog signal, and outputting the compensation control signal based on the direct current component. According to the invention, direct current interference can be effectively suppressed, air gap nonlinear errors can be compensated, influences caused by environmental changes and equipment aging can be adapted, high precision and high reliability of a measurement system can be maintained during long-term operation, and the requirement of high-precision field calibration can be met.

A series-type hybrid circuit breaker to provide protection against short circuit faults in DC or AC power circuits. A series-type hybrid circuit breaker (SHCB) forces a fault current into a high-frequency AC current with zero crossings and allows a mechanical circuit breaker to disconnect the faulty branch. The SHCB injects a transient counter voltage pulse via a pulse transformer into the main power loop upon detection of an overcurrent condition and forces the fault current to change its original direction and cross zero to a negative peak value. A generation power electronic circuit on the primary side of the transformer controls the discharge of a capacitor to generate the counter voltage pulse during the first phase of each switching cycle of the fault interruption process. The power electronic circuit then changes the polarity of the injected secondary voltage and forces the fault current to change direction and cross zero again.

The invention discloses an electric energy meter intelligent load control method based on electricity utilization behavior analysis, and relates to the technical field of electric power metering, and the method comprises the steps: collecting current waveform data and power parameters through an electric energy meter metering chip; according to the current waveform data, zero crossing point moment information of the alternating current is determined; generating a load control instruction according to a comparison result of the power parameter and a preset power threshold value; and determining a switch control moment according to the zero-crossing moment information and the action delay parameter of the built-in switch, and controlling the built-in switch to execute on-off operation at the zero-crossing moment according to the load control instruction and the switch control moment. By capturing the current zero crossing point moment, arc-free on-off control of the built-in switch is achieved, energy loss and electromagnetic interference in the switch action process are reduced, and the service life of the switch is prolonged; and meanwhile, a periodic detection mechanism is adopted, power supply is automatically recovered on the premise of ensuring power utilization safety, and the power supply reliability and the user experience are improved.

The invention discloses a high-power alternating-current impedance excitation circuit, a control method thereof and an electrolysis test system, and belongs to the technical field of power supplies and power electronics, the circuit is used as an alternating-current power supply in a high-capacity electrolysis test power supply, and the circuit is controlled by a controller to output an alternating-current signal so as to carry out an impedance test on an electrolytic bath. Compared with a full-bridge circuit, the alternating-current impedance excitation circuit adopts the multi-level converter, so that the output current harmonic content is low, the electrolysis efficiency is improved, the equipment loss is reduced, the economical efficiency of an electrolysis system is improved, stable operation of an electrolytic bath is ensured, and electrolysis interruption or faults caused by voltage fluctuation are reduced.

The invention relates to a battery internal resistance testing method and circuit, and the method comprises the steps: sequentially applying alternating current excitation signals of a plurality of frequency points distributed in a specified frequency scanning range to a tested battery in a frequency scanning mode, and enabling the amplitude of the alternating current excitation signals to be smaller than or equal to a preset amplitude, the distribution of the plurality of frequency points is related to an equivalent circuit model adopted by the tested battery; acquiring a voltage response signal generated by the tested battery under the action of the alternating current excitation signal, and acquiring an alternating current signal flowing through the tested battery; acquiring complex impedance data corresponding to each frequency point in the plurality of frequency points based on the voltage response signal and the alternating current signal; and performing parameter fitting on the complex impedance data of the plurality of frequency points and the equivalent circuit model to obtain parameter values related to the internal resistance of the battery, and generating a battery internal resistance test result. The scheme provided by the invention can improve the test efficiency and test precision of the internal resistance of the battery.

The invention, which belongs to the technical field of the energy storage converter, discloses an electrical parameter sensing-based service life monitoring system for a capacitor of a network-forming type energy storage converter, comprising the following steps of: synchronously acquiring a direct-current voltage signal and a three-phase alternating-current signal of a direct-current bus capacitor through an electrical parameter acquisition module to form a multi-dimensional feature vector; a state observer built in the ESR estimation module is used for analyzing the signal, a target capacitor ESR value is obtained, and a capacitor core temperature value is obtained through back-stepping through an electric-thermal coupling field analysis model of a core temperature back-stepping module in combination with preset capacitor surface temperature data; based on the ESR value and the capacitor core temperature value, a life prediction module calculates the residual life and health degree index of the capacitor; and the power scheduling module executes capacitor health degree-power output joint scheduling according to the health degree index, adjusts the power fluctuation range of the converter, and feeds back real-time working condition data to the electrical parameter acquisition module, thereby realizing accurate monitoring of the capacitor state and intelligent scheduling of the converter power.

The invention relates to a contact resistance and state detection method for an electromagnetic switch device of a railway vehicle, and the method comprises the steps: injecting an AC signal into a to-be-detected contact of the electromagnetic switch device, and then collecting an AC voltage signal of the to-be-detected contact; calculating a first resistance value of the contact to be measured according to the acquired alternating current signal and the alternating voltage signal; and further comparing the resistance value obtained by detecting the contact to be detected with a pre-configured resistance scale value, and judging whether the contact to be detected is in a good state or not according to a comparison result. On-line detection of the contact resistance of the electromagnetic switch device can be realized, and on the basis, judgment of the electricity storage state can be realized, so that the working safety and reliability of equipment are improved.

The invention discloses a method for constructing a correlation mathematical model of time-phased overcurrent capability and electric-thermal limit parameters of a power device of a high-voltage direct-hanging network-constructing energy storage system. Based on the short-time overload capacity requirement of the energy storage system, obtaining a selection range of an alternating current operation point; the alternating current operation point is selected in the range; calculating current flowing through a power device in a converter valve bridge arm of a direct-hanging converter of the energy storage system; calculating the junction temperature of the power device under the alternating current operation point; checking whether the current flowing through the power device and the junction temperature meet an electric-thermal limit constraint condition or not; and classifying the alternating current operation points according to the short-time overload capacity requirement, and further obtaining the active and reactive current safe operation range of the high-voltage direct-hanging grid-constructing type energy storage system.

The invention relates to a thermodynamic design method for distributed overhead ground wire alternating current ice melting, and belongs to the technical field of power transmission line ice melting. The method aims at solving the problems that an existing ice melting technology is high in power consumption, low in efficiency, difficult in equipment movement and lack of fine design of a current regulation and control strategy. The core of the technical scheme is that a thermal equivalent theoretical model and an electric heat flow coupling simulation model of the overhead ground wire are established, key thresholds such as wire protection current, critical ice melting current and maximum allowable current are determined through calculation, and an effective value of alternating current injected into the ground wire is flexibly adjusted by using a reactive power compensation device. According to the method, segmented ice melting according to needs can be achieved, energy consumption is remarkably reduced, the ice melting efficiency and safety are improved, and the needed device is small in size, convenient to move and deploy and suitable for various complex icing working conditions.

The invention provides a neutral-point potential control method and system for a three-level converter, and relates to the technical field of intelligent control, positive bus voltage and negative bus voltage are sampled, a voltage deviation value is calculated, an additional control quantity is generated according to the voltage deviation value and a symbol of alternating current, and the additional control quantity is obtained through a symbol function and proportional control processing; performing amplitude limiting processing on the additional control quantity to obtain an amplitude-limited additional control quantity; superposing the amplitude-limited additional control quantity on the positive modulation wave, negating the amplitude-limited additional control quantity, and superposing the negated amplitude-limited additional control quantity on the negative modulation wave to obtain a final positive modulation wave and a final negative modulation wave; comparing the final positive modulation wave and the final negative modulation wave with a carrier wave, and generating a driving signal of the power device; and the on-off of the switching device is controlled according to the driving signal, so that a corresponding level is output to realize neutral-point potential balance. According to the invention, neutral-point voltage low-frequency fluctuation and direct-current offset suppression can be realized at the same time.

An apparatus and method of application are described, which include a first switching arrangement configured to generate an alternating current from a power source. The alternating current flows through an inductive element of a resonant circuit for inductively heating a susceptor arrangement and heats an aerosol generating material of an aerosol generating device to generate an aerosol in a heating mode of operation. A driver circuit generates a control signal for controlling the first switching arrangement and a power mode switching arrangement is configured to disconnect at least a part of the driver circuit from the power source in a power saving mode of operation.

The invention relates to the field of battery management systems, and particularly discloses a battery equalization-alternating current self-heating integrated topology based on electromagnetic induction and a control method, the topology comprises a battery pack, a switch array, a multi-winding transformer, a signal acquisition and processing module, a control unit and a driving circuit, energy balance in the battery modules and among the modules is realized through the multi-winding transformer, and the same transformer winding is utilized to generate alternating current at low frequency to realize self-heating of the battery; the control method is based on battery voltage and temperature information, balancing and heating modes are dynamically switched, and flexible control over the heating rate and the balancing speed is achieved by adjusting PWM parameters. The system is high in integration level, does not need an external power supply, is high in expansibility, and is suitable for efficient thermal management and state equalization of various lithium ion battery systems in a low-temperature environment.

The utility model relates to a current detection device used for a copper bar, the current detection device is installed on the copper bar, one side or two sides of the copper bar are provided with gaps, the current detection device comprises a current detection chip and a shielding case, the shielding case covers the copper bar, and the current detection chip is parallel to the copper bar and is installed on the surface of the copper bar or above the surface of the copper bar. Compared with the prior art, one side or two sides of the copper bar are provided with the gaps, so that an internal magnetic field of the shielding cover translates in the horizontal direction when the alternating current changes, and the influence of the skin effect on the induction magnetic field intensity of the current detection chip is reduced; the current in the copper bar can be detected without an additional communication wire harness or a shell, so that the size is greatly reduced, and the cost is reduced; current detection can be carried out by arranging the current detection chip on the surface of the copper bar, the installation position can be flexibly adjusted according to the internal space requirement of the product, and the application range is wide.

The invention belongs to the field of two-level converter small signal and impedance modeling, and discloses a VSC impedance analysis method in a superposition oscillation component scene and a related device. The method comprises the following steps of: superposing an alternating-current voltage oscillation component, and establishing each steady-state quantity frequency domain model; establishing a main circuit steady-state frequency domain model; establishing each small semaphore frequency domain model based on the main circuit steady-state frequency domain model; establishing a main circuit small signal frequency domain model; constructing a PLL controller small signal model, a DC voltage controller small signal model and an AC current controller small signal model; constructing a small signal model of the alternating current modulation signal; and calculating the port impedance of the two-level current converter in the scene of superposition of the oscillation components based on a small signal model of the alternating-current modulation signal. According to the method, the VSC port impedance in the scene of superposition of the oscillation components can be accurately analyzed, and key technical support is provided for oscillation mechanism analysis and stability improvement of new energy access to a weak point network.

A thermal impedance monitoring process for a power module of a power converter for converting a DC current to an AC current, or converting an AC circuit to a DC current, where a semiconductor dissipates asymmetric losses between two half cycles of an AC frequency f of the AC current, said power module comprising at least a semiconductor die, a semiconductor die is attached to a stack of materials of layers for heat dissipation and / or electrical connection thereof, the process comprising: sampling and measuring a signal related to a junction temperature Tj of the semiconductor die at a frequency higher than twice the AC frequency of the AC current, calculating a duration [Delta] t = tTjmax-tTjmin between a moment tTjmax at which the junction temperature of the semiconductor die is at a maximum value and a moment tTjmin at which the junction temperature is at a minimum value in one cycle of the AC current, and storing the duration [Delta] t in a memory, repeating the step of sampling and measuring said signal and the step of calculating said duration at different times tx = t0 to tm during the operating life of the power module to provide a series of durations [Delta] t0 to [Delta] tm, and comparing the values of said durations [Delta] t0 to [Delta] tm for monitoring the evolution of said duration [Delta] t, and determining the evolution of the degradation of the thermal impedance of the power module.

To improve power efficiency of a synchronous motor in a wide speed range from a low speed to a high speed.SOLUTION: In a pole-number switching method, the current value of AC current supplied to an armature is reduced at low speed by increasing the number of poles and increasing the torque multiplier of the electric motor, thereby reducing copper loss, and loss at high-speed rotation (mainly iron loss) is reduced at high speed by decreasing the number of poles and lowering the voltage and frequency of the AC current supplied to the armature. Furthermore, a further power-efficiency improvement effect is provided by connecting the circuit such that, during driving of the electric motor, inverter power-supply current of an armature winding becomes a power supply for a field winding, and such that, during regenerative braking, current generated from the armature winding is regenerated to a battery efficiently.SELECTED DRAWING: Figure 2

A series-type hybrid circuit breaker to provide protection against short circuit faults in DC or AC power circuits. A series-type hybrid circuit breaker (SHCB) forces a fault current into a high-frequency AC current with zero crossings and allows a mechanical circuit breaker to disconnect the faulty branch. The SHCB injects a transient counter voltage pulse via a pulse transformer into the main power loop upon detection of an overcurrent condition and forces the fault current to change its original direction and cross zero to a negative peak value. A generation power electronic circuit on the primary side of the transformer controls the discharge of a capacitor to generate the counter voltage pulse during the first phase of each switching cycle of the fault interruption process. The power electronic circuit then changes the polarity of the injected secondary voltage and forces the fault current to change direction and cross zero again.

The invention relates to the technical field of inverter output power control, in particular to a micro inverter output power control method and system, and the method comprises the following steps: obtaining a grid-connected point AC voltage signal; based on a grid-connected point AC voltage signal, first phase-locked loop processing is performed in parallel, first phase information is extracted, and the first phase information comprises a voltage phase influenced by an interference component whose frequency is higher than a fundamental wave frequency; second phase-locked loop processing is carried out, second phase information is extracted, and the second phase information comprises the fundamental wave phase after the interference component is filtered out; calculating a phase disturbance quantity according to the first phase information and the second phase information; generating a correction phase according to the second phase information and the phase disturbance quantity; generating a corrected current command based on the corrected phase; and controlling the micro inverter to output alternating current according to the current correction instruction. The electric energy quality can be improved.

The invention discloses a wind power alternating-current fault ride-through method under a hybrid architecture, relates to the technical field of new energy grid connection and high-voltage direct-current transmission, and is used for solving the problem that stable control cannot be realized in the prior art. The method comprises the following steps: constructing a fault transient analysis model of an offshore wind power system for analyzing voltage supporting capability; detecting the voltage of the offshore alternating-current bus in real time, and judging an alternating-current fault stage; when the fault stage belongs to the fault period, controlling a grid-connected converter of a wind turbine generator and a wind field side MMC to be switched to a constant alternating current control mode, and injecting alternating current fault current; and when the fault stage belongs to the fault recovery period, controlling the current amplitude limiting value to gradually recover to the steady-state amplitude limiting value through the grid-connected converter of the wind turbine generator. The invention further discloses a wind power alternating current fault ride-through device under the hybrid architecture, electronic equipment and a computer storage medium. According to the invention, through cooperative control, smooth and impact-free transition from fault ride-through to steady-state operation is realized.

A vacuum pump which can suppress precipitation of by-products in a pump is provided. A vacuum pump 300 is provided, which includes a casing 310, a. rotor shaft 113 disposed, in the casing' 310, and a rotor blade 102 rotatable together with the rotor shaft 113, with gas being' exhausted by rotation of the rotor blade 102 the vacuum pump 300 further including heating means 340 for heating a gas flow" passage in the vacuum pump 300, wherein the heating means 340 has a coil 342, a heated, portion 343, which is a magnetic body heated, by electromagnetic induction by causing an. AC current to flow through the coil 342, and a high-permeability magnetic body 341 covering an opposite side to a front surface 344 side, on which the heated portion 343 is disposed, of the coil 342.

The invention provides a CT secondary circuit verification system and method, and the system comprises an alternating current source which is used for injecting a test current into a CT secondary circuit; the at least one current measuring device is used for measuring current values of different branches in the CT secondary circuit; and judging the wiring correctness of the CT secondary circuit by comparing the current values of the different branches. According to the invention, the efficiency of acceptance inspection and regular verification of the relay protection loop can be greatly improved, and a powerful guarantee is provided for safe and reliable operation of a power system.

The invention provides a frequency support control method and device of a flexible DC power transmission system. Inertia control is carried out on the actual frequency of the flexible direct current partition alternating current power grid, a direct current voltage dynamic correction value of a converter station in the flexible direct current power transmission system is obtained, a d-axis alternating current component and a q-axis alternating current component of the converter station are calculated, and then frequency support control is carried out on the flexible direct current power transmission system. The dynamic frequency response characteristic of the flexible direct-current power transmission system is remarkably improved through inertia control, and the frequency stability of the flexible direct-current partition alternating-current power grid is guaranteed. According to the method, inertia control is carried out on the actual frequency of the flexible direct-current partitioned alternating-current power grid, the frequency change rate of the flexible direct-current partitioned alternating-current power grid is rapidly suppressed at the initial stage of the fault, the frequency drop amplitude of the flexible direct-current partitioned alternating-current power grid is reduced, and the frequency of the flexible direct-current partitioned alternating-current power grid is prevented from entering a dangerous interval.

The invention relates to an impedance modeling method and device and computer equipment. Comprising the steps that disturbance voltage is injected to the alternating current side of a main circuit, a first relation between a modulation small signal and an alternating current small signal is obtained through alternating current control topology, the disturbance voltage and a phase angle small signal are correlated through a phase-locked loop, and a second relation between the modulation small signal and an alternating voltage small signal is determined; injecting disturbance voltage to the direct current side of the main circuit, and determining a third relationship between the modulation small signal and the alternating current small signal and a fourth relationship between the direct current small signals based on the alternating current control topology and the direct current control topology; and finally, impedance modeling is carried out in combination with a frequency small-signal model, so that self-impedance and coupling impedance characteristics of an alternating current side and a direct current side can be accurately reflected, and a basis is provided for analyzing system stability and optimizing a control strategy.

A modular power hub includes: an inverter / charger module; a battery control module; and a storage battery, wherein the inverter / charger module is operable to: receive electric grid power and to charge at least one of: a removable battery coupled to the battery control module and the storage battery; and receive electric current from at least one of: a removable battery coupled to the battery control module and the storage battery, and convert that electric current to AC current.

The invention provides a superconducting diode and a preparation method thereof. The preparation method comprises the following steps: modulating the high-temperature superconducting Josephson junction device: connecting the first electrode to a power supply, connecting the second electrode and the third electrode to a voltage measuring device, and grounding the fourth electrode; reducing the environment temperature of the high-temperature superconductive Josephson junction device to a preset temperature lower than the superconductive transition temperature; direct current pulse current with a preset pulse signal is applied to the first electrode, so that a volt-ampere characteristic curve of the high-temperature superconducting Josephson junction device has a rectification characteristic; and applying an alternating current with a predetermined microwave signal to the first electrode, so that a voltage step appears on one side of the volt-ampere characteristic curve, and the other side of the volt-ampere characteristic curve is in a superfluid state. The superconducting diode is obtained by carrying out direct current modulation and alternating current modulation on the high-temperature superconducting Josephson junction device, and high rectification efficiency and high working temperature can be achieved.

A power transfer device and system include an AC delivery path, a DC delivery path, and a circuit to combine the power from the AC delivery path and the DC delivery path. The AC delivery path includes a source bridge circuit that couples AC source to a source DC link. The source bridge has cross-connected switches to convert an AC current from the AC source to a pseudo DC (direct current) current, and the source DC link transfer the energy as a DC current. The DC delivery path includes a battery, a battery interconnection circuit, and a battery DC link to transfer energy from the battery as a DC current. Both the AC delivery path and the DC delivery path couple to a consumer bridge circuit having cross-connected switches to convert the DC current to an AC current for a microgrid.

A power conversion device that converts DC power into three-phase AC power and outputs the three-phase AC power includes: an AC current sensor that detects two-phase current values among three-phase AC currents generated by the three-phase AC power; a target current calculation unit that calculates a target current based on a target torque; a voltage command calculation unit that calculates a voltage command value based on the target current and a detection value of the AC current sensor; and an AC current sensor diagnosis unit that determines abnormality of the AC current sensor based on a detection value of the AC current sensor. The AC current sensor diagnosis unit includes: a first diagnosis unit that determines the abnormality based on a two-phase voltage command value obtained by converting the voltage command value into a value in a two-phase orthogonal coordinate system with any output phase as a reference; and a second diagnosis unit that determines the abnormality based on a two-phase current detection value obtained by converting a detection value of the AC current sensor into a value in the two-phase orthogonal coordinate system. The AC current sensor diagnosis unit performs switching of determination between the determination of the abnormality by the first diagnosis unit and the determination of the abnormality by the second diagnosis unit corresponding to an operation condition of the power conversion device.