495 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.

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.

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 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.

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.

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 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.

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.

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.

The alternating-current synchronous motor comprises a stator shell and a rotor, the stator shell is arranged on the ground, the rotor is arranged in the stator shell through an end cover and an insulating bearing, the rotor comprises a rotating shaft and a rotor iron core, the rotor iron core is arranged on the rotating shaft, and a tooth groove set is formed in the rotor iron core in a concave mode. The tooth groove group is composed of a plurality of adjacent tooth grooves, and the windings are arranged in the tooth grooves. The motor has the advantages that the relative positions of the stator and the rotor tooth grooves are collected through the rotor position sensor, the current of the three-phase alternating current and rated torque input are collected through the current sensor, the magnitude of the current of the three-phase synchronous alternating current is controlled, the torque of the motor is controlled, and winding arrangement is optimized, so that the reliability of the motor is improved. In the working process, the magnetic potential direction of the rotor is perpendicular to the magnetic potential direction of the stator at any position, then the maximum torque under the current is output, and meanwhile, the stator permanent magnet cannot be demagnetized due to the change of the magnetic field of the rotor.

The application discloses a method for controlling hybrid MMC sub-modules to clear DC short-circuit fault current. The method detects the real-time size of AC voltage, calculates the bridge arm voltage according to the principle of limiting AC current change and not affecting the speed of DC fault current clearing, and determines the number of improved sub-modules (sub-modules capable of providing counter electromotive force, such as full-bridge sub-modules) in each bridge arm according to the bridge arm voltage. Compared with the conventional method of directly locking all sub-modules to clear DC fault current, the application reduces the bridge arm current during the DC fault current clearing process, alleviates the overvoltage of the improved sub-modules, limits the influence on the speed of DC fault clearing, and improves the safety of the hybrid modular multilevel converter during the process of clearing DC fault current.

An impedance measuring device (50) comprises a plurality of electrical paths (81) connected to both ends of each battery cell (42) connected in series, an AC current generation unit (51, 84) that enables an AC current to flow through the battery cells, a voltage fluctuation measuring unit (52, 86) that measures voltage fluctuations in response to the AC current, a connection actuation unit (54) which, when the impedance of a cell to be measured is measured, causes the AC current of the AC current generation unit to flow through a pair of electrical paths located on the positive and negative sides of the cell to be measured, and connects the voltage fluctuation measuring unit to a pair of electrical paths also located on the positive and negative sides of the cell to be measured, but which are a different combination to the pair of electrical paths through which the AC current of the AC current generation unit flows.and a calculation unit (54) that calculates the impedance value of the cell to be measured on the basis of an amplitude and a voltage fluctuation of the AC current.

The present invention relates to a DC and AC-compatible electric vehicle charging device and, more specifically, to an electric vehicle charging device for charging a battery of an electric vehicle using AC current of a power supply unit. The electric vehicle charging device comprises: an ESS for storing and outputting DC current; an ESS switching unit for charging the electric vehicle using the ESS or charging the ESS using the AC current of the power supply unit; a DC switching unit for charging a DC electric vehicle; and an AC switching unit for charging an AC electric vehicle, and thus can charge both DC electric vehicles and AC electric vehicles and can use the output of the ESS to charge an electric vehicle when power supply is not normal. The DC and AC-compatible electric vehicle charging device comprising the ESS according to the present invention for solving the technical problem may comprise: an AC-DC converter for converting the AC current of the power supply unit into DC current; a DC-AC converter for converting the DC current of the ESS into AC current; and a control unit for controlling the switching units.

The impurity detection auxiliary device (100) includes: a pipe (102) through which a liquid to be inspected flows; a first electrode and a second electrode which are arranged in the pipe (102) and are configured to be able to apply an alternating voltage to or superimpose an alternating current on the liquid to be inspected in a space extending between a first position and a second position that are offset from each other in the extension direction of the pipe (102); a power supply portion (106) which applies an alternating voltage between the electrodes or superimposes an alternating current; a measurement portion (108) which measures a current generated between the electrodes due to the application of the alternating voltage or measures a voltage generated between the electrodes due to the superposition of the alternating current; and a calculation portion (110) which calculates a resistance of the liquid to be inspected using the measurement result of the measurement portion (108), the resistance of the liquid to be inspected being a criterion for determining whether or not the liquid to be inspected contains an electrically conductive impurity.

The invention provides a motor control method and device of an air compressor, a vehicle and a storage medium, and the method is applied to the field of vehicles. The method comprises the steps that the current temperature of a motor is calculated based on the obtained direct-current voltage value of an air compressor controller at the target moment, the obtained water temperature value of a cooling water inlet of the air compressor controller, the obtained alternating current of the motor and the obtained rotating speed of the motor; and if the current temperature is greater than the allowable temperature of the motor, acquiring the current operation condition of the motor, and controlling the motor to operate in a power-reducing manner or stop operating according to a preset power-reducing strategy according to the current operation condition. According to the method, installation of a temperature sensor and lead-out wire harnesses and connectors is omitted, the temperature of the motor is calculated, a calculation result is transmitted to an FCU through a communication bus, and meanwhile a corresponding protection mechanism is executed according to a comparison result of the current temperature of the motor and the allowable temperature of the motor.

The application provides a kind of staggered parallel DCDC converter and its control method, belongs to alternating current injection technical field.The DCDC converter includes: the converter includes multiple DCDC lines and controller, wherein each DCDC line includes inductor, upper bridge arm power tube and lower bridge arm power tube, current sensor;The one end of inductor is used to connect with the positive pole of power supply, the other end of inductor is connected with the one end of upper bridge arm power tube, the other end of the upper bridge arm power tube of each DCDC line is connected with each other, for output positive phase voltage, the one end of lower bridge arm power tube is connected with the one end of upper bridge arm power tube, the other end of the lower bridge arm power tube of each DCDC line is connected with each other, for connecting with the negative pole of power supply, current sensor is connected with the other end of upper bridge arm power tube, controller is connected with the control end of each upper bridge arm power tube and lower bridge arm power tube, the other end of each inductor, current sensor.

The invention discloses an oil-immersed transformer winding temperature controller verification device, method, equipment and medium, and relates to the technical field of electrical equipment testing, the device comprises an intelligent current source module, a signal acquisition module, a central processing module and a man-machine interaction module; a programmable alternating current signal is generated through the intelligent current source module, and the dynamic load working condition of the transformer from no load to full load can be continuously simulated, so that a winding temperature rise curve is completely reproduced, and the defect that a traditional fixed point test cannot detect a nonlinear temperature rise error is overcome; a signal acquisition module is used for synchronously acquiring the current of a heating resistor, a 4-20mA temperature signal and the state of a microswitch, and dynamic current control and a temperature-current correlation analysis algorithm of a central processing module are combined; the automatic and accurate measurement and judgment of the temperature controller potentiometer calibration precision, the winding temperature indicating value error and the microswitch operating value are realized.

A drive system includes: a first inverter that outputs first alternating current by switching first direct current with a switching element (first switching element), to an electric motor generating power for propelling a vehicle; a second inverter that supplies, to the electric motor, second alternating current having the same frequency as the first alternating current by switching direct current with a switching element (second switching element); and a control part that performs PWM control on the first inverter and the second inverter such that an ON-time of the first switching element in one cycle of the first alternating current becomes longer than an ON-time of the second switching element when the direct current is smaller than the direct current.

This invention discloses a magnetically levitated grain vibrating screen, belonging to the field of grain impurity removal technology. It includes a base with a magnetic coupling module; a screen body mounted above the base, with a permanent magnet array corresponding to the magnetic coupling module at its bottom; the magnetic coupling module includes a drive assembly mounted on the base, comprising multiple independent drive coils, each connected to an independently adjustable AC power supply; the AC power supply generates a changing driving magnetic field by inputting AC current of a preset frequency and phase to the corresponding drive coil, and the driving magnetic field couples with the permanent magnet array, driving the screen body to perform multi-degree-of-freedom force-driven motion. The screen body of this invention can perform multi-degree-of-freedom force-driven motion, realizing reciprocating swing motion, and improving the screening efficiency for fine impurities in grain.

The invention belongs to the technical field of battery detection, and particularly relates to a naked battery cell defect detection method and device, and the method comprises the steps: 1, in a pole piece processing flow, in an interval from the completion of a baking process to the start of a winding process, obtaining a pole piece surface image after the completion of each process or a part of processes in the interval; step 2, applying a preset alternating current to the pole piece to obtain an infrared thermal distribution image of the pole piece; 3, applying a preset direct-current high voltage between the positive electrode and the negative electrode of the naked battery cell to obtain an infrared thermal distribution image of the naked battery cell; 4, acquiring an X-ray image of the naked battery cell; and 5, inputting the obtained surface image of the pole piece, the obtained infrared heat distribution image of the pole piece, the obtained infrared heat distribution image of the naked battery cell and the obtained X-ray image of the naked battery cell into a preset AI analysis model based on deep learning, and outputting a defect detection result of the naked battery cell through the defect analysis model. According to the invention, the defect detection and identification precision and capability are improved.

The present application relates to the technical field of inverter output power control, and particularly relates to a micro inverter output power control method and system, the method comprising the following steps: acquiring a grid-connected point alternating voltage signal; based on the grid-connected point alternating voltage signal, performing in parallel: first phase-locked loop processing, extracting first phase information, the first phase information containing a voltage phase affected by an interference component with a frequency higher than a fundamental frequency; second phase-locked loop processing, extracting second phase information, the second phase information containing a fundamental phase after filtering out the interference component; calculating a phase disturbance amount 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 amount; generating a corrected current command based on the correction phase; and controlling a micro inverter output alternating current according to the corrected current command. The above can improve power quality.

A vehicle propulsion system including a system controller for determining a rotational speed and a rotational torque in response to a user input and a vehicle operating mode, a battery for supplying a DC current, an electric motor configured to generate the rotational torque at the rotational speed in response to an AC voltage, an inverter for transforming the DC current into the AC current using a first transistor and a second transistor, and an inverter controller for determining a dead time in response to the rotational torque and the rotational speed and for removing a first switching control signal from the first transistor, waiting a time duration equal to the dead time, and applying a second switching control signal to the second switching transistor and wherein the dead time is continuously updated in response to a change in the torque and a change in the rotational speed.

A method of controlling a power converter in a power transmission network. A first amplitude limit value for a first AC current output from an AC side of the power converter is received. A second amplitude limit value for a negative phase sequence component of the first AC current is received. The negative phase sequence component is measured to provide a measured second amplitude. The negative phase sequence component is regulated to flow with a second amplitude that is the lesser of the measured second amplitude and second amplitude limit value. A positive phase sequence component of the first AC current is regulated to flow with an amplitude not exceeding a regulated third amplitude. The third amplitude is set using a function such that the second amplitude and the third amplitude provide a first amplitude for the first AC current that is substantially equal to the first amplitude limit value.

The application provides a performance test method, system, device and medium of a parallel converter, the parallel converter comprising a plurality of first devices and a plurality of second devices; each device comprises at least two modules; the module types comprise first modules and second modules; the method comprises: controlling the first modules to operate in a voltage source mode and the second modules to operate in an alternating current source mode; sending a power reference value instruction to realize parallel power test of each module; controlling the first devices to operate in the voltage source mode and the second devices to operate in the alternating current source mode; sending the power reference value instruction to realize parallel power test of the devices, and obtaining a performance test result of the parallel converter. By controlling part of the modules or devices in the parallel converter to be in the voltage source mode and simultaneously controlling another part of the modules or devices to be in the alternating current source mode, the power demand for external test power supply can be reduced.

This utility model discloses a high-temperature detection and alarm circuit for a ship transformer, belonging to the technical field of ship transformers. It includes an overheat detection unit, the input of which is connected to the output of the ship transformer. The overheat detection unit is used to detect the temperature of the ship transformer. The output of the overheat detection unit is connected to the input of an alarm unit, which issues an alarm when the ship transformer temperature is high. The overheat detection unit includes current transformers CT1 and CT2. The input of current transformer CT1 is connected to the output of L3 of the ship transformer, and the output of current transformer CT1 is connected to the input of current transformer CT2. The input of current transformer CT2 is also connected to the output of L2 of the ship transformer. Current transformers CT1 and CT2 are used to obtain the AC current of the ship transformer. This utility model uses an LED D3 to emit light, and simultaneously the alarm sounds, prompting the operator to take timely cooling measures as the transformer temperature is too high.

The application provides a power battery heating noise processing method and device and an electric vehicle, and relates to the field of noise control.The application comprises the following steps: receiving a power battery heating instruction, and generating a d-axis current instruction and a q-axis current instruction according to the power battery heating instruction; outputting a q-axis voltage through a PI controller according to the q-axis current instruction, so as to control the q-axis current with an output value of zero; controlling a d-axis voltage to be output through hysteresis control according to the d-axis current instruction; generating a random factor at a preset frequency, adjusting the amplitude of the d-axis voltage according to the random factor, randomly adjusting the current slope of the motor at each pulse current point, generating a random pulse current acting on the power battery, and making the noise generated in the battery heating process randomly distributed, so as to solve the problem that the existing power battery heating process using high-frequency constant-frequency alternating current generates high-frequency sharp and piercing noise.