490 results about "Dc current" patented technology

The invention discloses a rapid three-dimensional electromagnetic simulation method and verification device for a large-scale uninsulated coil, and aims to solve the problems of large calculation load, difficulty in homogenization, poor field-circuit coupling convergence and low result precision of the three-dimensional simulation of the existing large-scale uninsulated coil. The simulation method comprises the following steps: establishing a homogenized coil which does not divide specific turns, and setting anisotropic resistivity; constructing a current source area intercepted on the coil body and a free turn-to-turn resistance area connected in parallel with the current source area; applying current source excitation according to an open loop / closed loop coil; and the precision is ensured through radial grid encryption and result convergence verification. The verification device comprises a three-dimensional multi-turn verification coil, a direct current source, a multi-direction alternating external field applying module and a voltage and magnetic field measuring unit, direct current is supplied, an alternating external field is applied, and the simulation accuracy is measured and verified in real time. The method is simplified in modeling, rapid in calculation, good in convergence and high in precision, adapts to open-loop / closed-loop and single-cake / multi-cake coils, and is suitable for large uninsulated superconducting coils in rotary and linear motors, nuclear fusion equipment and the like.

The invention relates to the technical field of high-voltage direct-current transmission, and particularly provides an LCC-full-bridge MMC series light HVDC converter station control method, which comprises the following steps: a rectification side of a power grid commutation converter adjusts direct-current power through an outer ring and an inner ring adopts linear trigger angle control to generate a trigger pulse; transformer tap adjustment is supplemented; on the basis of the established stable direct current system, an inversion side selects a minimum trigger angle as a control signal by coordinating three control rings of a turn-off angle, direct current voltage and direct current to form a control system; the full-bridge modularized multi-level converter is switched to a power grid following and network construction control mode according to power grid conditions; and when a direct current fault is detected, setting the trigger angle of the commutation converter of the power grid to be 90 degrees and switching the full-bridge modular multi-level converter to an STATCOM mode, thereby realizing direct current fault ride-through without locking the converter. According to the invention, direct-current fault rapid ride-through of the non-locking converter is realized.

The invention relates to the technical field of power electronics, in particular to a portable load adaptive bidirectional charging and discharging circuit module. The module comprises a battery and a load port. The first half-bridge is composed of a gallium nitride switch, and the second half-bridge is composed of a silicon-based field effect transistor; a main winding of the coupling inductor is connected with two half-bridge switch nodes, and a secondary winding outputs induced voltage to provide bias power supply through rectification and filtering; an auxiliary resonant branch comprising an auxiliary switch and a resonant capacitor is connected in parallel to two ends of the switch, and the starting time sequence of the auxiliary switch is ahead of the first gallium nitride switch; the control unit determines a direct current and a high-frequency ripple component according to the shunt resistor and the secondary winding signal, and generates a PWM signal in combination with the port voltage to control the on and off of all the switches. According to the scheme of the invention, self-bias power supply and high-precision composite current detection are realized, the switching loss is reduced, and the energy conversion efficiency is improved.

The invention discloses a flexible DC power transmission system grid following-grid construction hybrid control method, and the method comprises the following steps: obtaining the voltage and current of a receiving end MMC grid connection point, and carrying out the dq decomposition, thereby obtaining a d-axis component and a q-axis component under a dq rotating coordinate system; acquiring actual values and related reference values of direct-current voltage output by the receiving-end MMC, alternating-current voltage and frequency of a grid-connected point of the receiving-end MMC and average capacitance voltage of a sub-module; sequentially calculating a phase reference value of the receiving end MMC, a d-axis current reference value and a q-axis current reference value of the grid connection point, a d-axis voltage reference value and a q-axis voltage reference value of the differential mode voltage, a direct current reference value and a direct current modulation ratio reference value; and calculating the reference value of the modulation voltage of the receiving end MMC under the abc static coordinate system. The control method has the advantages of adapting to wide-range short-circuit ratio change of the receiving-end power grid, guaranteeing reliable transmission of power under the condition of wind speed change, and still maintaining synchronous operation when the receiving-end alternating-current power grid seriously breaks down.

The invention belongs to the technical field of superconducting cable operation monitoring, and particularly discloses a superconducting direct-current cable full-load operation testing device and method, and the testing device comprises a functional loop unit, a power supply unit and a measurement and control unit. The functional loop unit comprises a direct current loop and a high potential generation loop; the direct-current loop comprises a direct-current power supply, and the direct-current power supply is arranged in the electromagnetic shielding structure and used for applying test current to the superconducting direct-current cable; the high-potential generation loop is used for applying test voltage to the superconducting direct-current cable; the power supply unit is used for providing isolated power supply for the direct current loop and the high potential generation loop; and the measurement and control unit is used for regulating and controlling the functional loop unit, monitoring the state of the functional loop unit and regulating and controlling the output current of the direct current loop and the output voltage of the high potential generation loop. The test cost and the implementation difficulty can be reduced, and the full-load working condition simulation accuracy and the test safety are improved.

The invention relates to the technical field of Hall sensors, and provides a Hall element with a triple isolation structure and a preparation method thereof.The Hall element comprises two pairs of Hall contact areas participating in electrical connection and oxide isolation structures located on the two sides of the Hall contact areas and having a certain gap distance. The oxide buried layer completely isolates the Hall plate area in the vertical direction, the Hall plate is completely isolated from the outside through the isolation structure and the oxide buried layer, external direct current interference is reduced to the maximum extent, meanwhile, the thickness and the current path of the Hall plate are controlled, and the effect of reducing noise interference while the sensitivity is improved is achieved. A three-circle surrounding structure is formed by utilizing a P well in contact with the side face of a Hall plate, a PBL in contact with the vertical bottom of an oxide buried layer and connected with the P well on the side face of the Hall plate, an NBL tightly attached to the lower surface of the PBL, an N well connected with the NBL and surrounding the Hall plate and the P well, and a P well connected with a substrate and surrounding the outermost layer, and Hall voltage changes caused by substrate noise and EMI electromagnetic interference are prevented.

A battery charging system for an electric vehicle including a dual use direct current to direct current converter including a direct current to alternating current converter and a transformer for generating a rotor winding current in response to a first direct current in a propulsion mode and for generating a charging current in response to a charging mode.

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.

Techniques are provided for automatically determining when voltage and current levels occur when a DC input of a radio is drawing substantially constant power through electrical conductors from a DC voltage converter. Such voltage and current level occurring when such power draw is substantially constant can then be used to determine a resistance of the electrical conductors. Subsequently, the resistance can be used to vary an output voltage of the DC voltage converter when the power draw, and thus the direct current drawn through the electrical conductors, varies.

The embodiment of the invention relates to the technical field of power systems, in particular to a method, equipment and a system for detecting the maximum junction temperature of a multi-chip parallel device. The method comprises the following steps: collecting direct current distribution data of each chip in the multi-chip parallel device; obtaining on-state voltage drop data of the multi-chip parallel device in a forward conduction state and a reverse follow current state; inputting the on-state voltage drop data and the direct current distribution data into a pre-established current-junction temperature-on-state voltage drop function relationship, and calculating junction temperature data of each chip; and comparing the junction temperature data of each chip, and determining the maximum junction temperature data in the multi-chip parallel device and the corresponding chip. The method can break through the limitation that a conventional on-state voltage drop monitoring inversion technology can only obtain the average junction temperature of the chip, and achieves the precise positioning of the chip with the highest junction temperature in the device.

A base disposed in a plasma processing chamber. An electrostatic chuck disposed on an upper portion of the base, the electrostatic chuck including a first part and a second part. A first heater electrode layer group including at least one heater electrode layer disposed in the first part. A second heater electrode layer group including at least one heater electrode layer disposed in the second part. A power source is electrically connected to the first heater electrode layer group and the second heater electrode layer group. A controller configured to periodically and sequentially supply DC current from the power source to heater electrode layers included in the first heater electrode layer group and heater electrode layers included in the second heater electrode layer group.

The application provides a power flow inversion method of a direct current power transmission system, the direct current power transmission system comprising a power sending end and a power receiving end, the power sending end comprising a first converter, the power receiving end comprising an electrically connected second converter and at least one third converter, the type of the first converter being the same as that of the second converter, the type of the second converter being different from that of the third converter, the power flow inversion method comprising: determining whether the direct current power transmission system receives a power flow inversion instruction; in the case that the direct current power transmission system receives the power flow inversion instruction, obtaining a direct current voltage instruction value, and controlling the direct current voltage of the first converter to follow the change of the direct current voltage instruction value, the direct current voltage instruction value being stepwise reduced from a first predetermined value to a second predetermined value; controlling the active power of the second converter according to the direct current voltage of the first converter; and controlling the direct current of the third converter to remain unchanged. The method can overcome the complexity and current impact problem of the power flow inversion operation.

The utility model discloses a miniature 60A gradient magnetic conductivity direct-current-resistant current transformer which comprises a bottom shell, a winding magnetic ring, an electronic wire with a terminal and an epoxy glue layer. A shell cavity is formed in the bottom shell; a wire connecting seat extending upwards from the bottom along the shell wall is arranged in the shell cavity; a plurality of wire connecting grooves are formed in the wire connecting seat at intervals, and each wire connecting groove is provided with a through hole in the top surface of the wire connecting seat and one surface, opposite to the shell wall, of the wire connecting seat; each external connection end of the winding magnetic ring is correspondingly connected with one wiring end of the electronic wire with the terminal to form a connection part, and each connection part is reinforced by tin immersion; the winding magnetic ring is installed in the shell cavity, the electronic wire with the terminal is arranged outside the bottom shell, and the connecting part penetrates into the wire connecting groove and is positioned through the wire connecting groove. The epoxy glue layer is formed by pouring epoxy glue into the shell cavity after the winding magnetic ring and the electronic wire with the terminal are installed. According to the utility model, the size reduction and miniaturization of the mutual inductor can be realized under the condition that the connection between the winding magnetic ring and the electronic wire is not influenced.

Methods and electric circuit arrangements for protecting metallic components in an electrolytic medium from corrosion due to direct-current (DC) stray current (Is) from a power supply system. The DC stray current may be jointly registered as a total sum current across all active conductors together with the protective conductor of the power supply system by a DC total differential-current sensor. Alternatively, a combined DC differential-current sensor is switchable by a switching device, a differential current being registered across all active conductors or the DC stray current being registered as a total differential current across all active conductors and the protective conductor. Alternatively, a differential current may be registered across all active conductors by a DC current sensor at the protective conductor and the DC stray current computed by forming differences of the differential current registered by the differential-current transformer and of the protective conductor registered by the DC current sensor.

The invention discloses a low-frequency ripple current suppression circuit and a power supply system with a low-frequency ripple current suppression function. The low-frequency ripple current suppression circuit comprises a first booster circuit and a second booster circuit, the first booster circuit comprises a first inductor, a first switch group and a first capacitor, wherein the first switch group comprises a first switch and a second switch. The second booster circuit comprises a second inductor, a second switch group and a second capacitor, wherein the second switch group comprises a third switch and a fourth switch. The low-frequency ripple current suppression circuit receives a direct current having a ripple component, and absorbs the ripple component through the first booster circuit and the second booster circuit.

The invention discloses a control method for supporting weak power grid operation by a network construction type SVG (static var generator), relates to the technical field of power electronics, and solves the problems that in the prior art, AC voltage cannot be actively constructed, an effective dynamic coordination mechanism is lacked with DC current control of a sending-end converter station, and the reliability of the system is poor. The system voltage supporting capability is insufficient and the direct current dynamic response performance is limited under the weak power grid working condition. According to the method, cooperative control of a network-forming SVG and an LCC-HVDC sending end converter station is adopted, specifically, the stability of power transmission of the LCC-HVDC system is ensured through a direct current control mode, the network-forming SVG generates a voltage vector reference through power synchronous control and adopts voltage and current double-closed-loop control, so that the network-forming SVG has the active voltage supporting capacity, and the stability of power transmission of the LCC-HVDC system is improved. Therefore, the dynamic response speed and the overall stability of the system under the weak power grid working condition are remarkably improved, and coordinated optimization of reactive compensation and direct-current power control is achieved.

The utility model relates to a special testing device for a graphite contact high-voltage switch based on a 20A constant current source, which relates to the field of high-voltage switch testing and comprises a microprocessor module, a constant current source module, an output terminal module, a current output test line module, a voltage signal test input line module, a signal acquisition and conditioning module and a speed measurement sensor module. The constant current source module outputs 20A direct current to the contact of the graphite contact high-voltage switch to be tested; the voltage test line collects the voltage between the contacts in a built-in four-wire system mode, and the voltage is processed by the signal acquisition conditioning module and then sent to the microprocessor module. The speed measurement sensor collects the speed of the moving rod. And the microprocessor module determines the action time of the silver-plated main contact according to the voltage signal and performs compensation calculation to obtain the action time of the graphite arc contact as the closing or opening time. The utility model solves the problem that the traditional method cannot accurately measure the time parameter of the graphite contact high-voltage switch, and has the advantages of accurate measurement and strong interference resistance.

A system and a method operate in a first mode and a second mode. In the first mode, the system and the method control the DC current and quadrature current applied to a motor with an internal permanent magnet to achieve a desired speed and torque over a range of internal operating temperatures of the motor without exceeding a maximum stator current. If a calculated stator current exceeds a maximum stator current, the system and the method operate in the second mode, in which they control the DC current and the stator current to keep the calculated stator current below the maximum stator current.

According to an aerosol-generating device according to an embodiment, in a case where a flange temperature sensed by a flange temperature sensor is included in a preset reference temperature range, a switching frequency of a power conversion unit is swept in a reference frequency range and at least one DC current value is acquired from a current sensing sensor; and generates temperature data for estimating the temperature of the susceptor on the basis of the DC current value.

This invention relates to the field of power transformer protection technology, and discloses a transformer DC bias suppression system and method. The method includes collecting subway operation, power grid structure, and soil geological parameters; establishing a dynamic calculation model based on these parameters to generate distribution data of rail potential, stray current, and ground potential; constructing a bias assessment model to calculate the dynamic DC current flowing through the transformer neutral point and the excitation current distortion; using a random forest algorithm for evaluation, outputting a quantitative impact level and a set of key factors; and based on this level, key factors, and transformer grounding method, formulating a suppression strategy that includes configuration parameters of a silicon carbide PiN diode active suppression device and a grounding optimization scheme. This invention achieves accurate assessment and targeted suppression of DC bias problems caused by subways.

This invention relates to a graphene spin device, its construction method, and a method for measuring nonlocal signals. The construction method of the graphene spin device includes the step of setting electrodes on the graphene surface; wherein, the electrodes are set by magnetron sputtering, using a direct current, and the magnetron sputtering power is 200±10W. This invention creates defects at the contact point between the graphene and the electrodes through magnetron sputtering under specific conditions, forming serrated graphene edges. Then, it utilizes the unique magnetism of graphene to construct a spin device. This spin device has high spin polarization and long spin transport distance. More importantly, this spin device relies solely on the magnetism of the graphene itself for spin injection and spin detection, providing a new approach for the development of graphene spin devices. It can be used for nonlocal measurements at room temperature, has low requirements for experimental environmental conditions, and is beneficial for exploring some nontrivial electrical mechanisms.

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.

Embodiments of the present application provide an access method and device of a power supply unit, a storage medium and an electronic device. The method comprises: collecting current voltage values of a plurality of image processing units in a server at a current time; determining a mode switching instruction in the case that the plurality of image processing units include a first processing unit according to a comparison result between a standard voltage value corresponding to each of the plurality of image processing units and the current voltage value; and sequentially connecting at least one power supply unit in a sleep mode to a power supply circuit for supplying power to the plurality of image processing units according to the mode switching instruction until at least one circuit parameter corresponding to each of the plurality of image processing units meets a target condition, wherein the power supply unit is used to convert alternating current into direct current for supplying power to the plurality of image processing units.

The invention discloses a multifunctional tester for electric power new energy electrical equipment, and relates to the technical field of new energy electrical multifunctional tests. The multifunctional tester for the electric power new energy electrical equipment comprises a tester main body, a protective shell and a protective cover, the upper surface of the tester main body is fixedly connected with a direct-current voltage measurement digital display meter, a direct-current measurement digital display meter, an alternating-current voltage measurement digital display meter, an alternating-current measurement digital display meter, a power supply display lamp, a working position display lamp, a zero position display lamp and an alternating-current and direct-current conversion switch, and the interior of the tester main body is fixedly connected with an isolation voltage regulator. The top of the isolation voltage regulator is provided with an adjusting knob, the upper surface of the tester main body is provided with a power jack and a wiring hole, and the inner surface of the protection housing is fixedly connected with a first elastic plate and a second elastic plate, thereby solving the blank field of no test instrument for the AC impedance of the wind driven generator rotor, and enabling the test work difficulty of a new energy station to be simplified.

This invention discloses a coordinated control strategy for LCC and MMC in DC distribution networks. The strategy employs parallel operation of the LCC and MMC, with their DC sides connected to the same DC bus and simultaneously supplying power to the DC distribution network. When the transmission power is low or power flows in reverse, the LCC is deactivated, and the MMC assumes all the transmission power. When the transmission power is high, the LCC is activated and assumes most of the power. Considering the characteristics of LCC and MMC converter stations, the MMC uses constant DC voltage control and constant reactive power control, while the LCC uses constant DC current or constant DC power control. This invention utilizes the LCC to replace the MMC in assuming part of the transmission power, reducing the number and capacity of MMC devices in the DC distribution network. The coordinated control strategy for steady-state operation of LCC and MMC in the DC distribution network employs parallel operation of the LCC and MMC, with their DC sides connected to the same DC bus and simultaneously supplying power to the DC distribution network.

The invention discloses a water electrolysis hydrogen production system and a cold start control method, and belongs to the technical field of water electrolysis hydrogen production. A water electrolysis hydrogen production system comprises an electrolytic bath and further comprises a modulated hydrogen power source for providing electric energy for the electrolytic bath, the modulated hydrogen power source is used for providing current with adjustable alternating current and direct current components for the electrolytic bath, and the numerical value of the direct current component is larger than or equal to the maximum value of the alternating current component. The direct-current component is used for participating in a polarization reaction of electrolytic hydrogen production, and the alternating-current component is used for additionally heating the electrolytic cell in a cold start process. According to the water electrolysis hydrogen production system, by specially increasing the alternating current component proportion and / or frequency of the output current of the hydrogen production power supply, namely increasing the active power generated by the alternating current component, more power supply output power is used for heating the electrolytic cell; therefore, the temperature rise starting performance of the hydrogen production system is greatly improved on the basis of not changing the technological process of the hydrogen production system and not increasing additional system auxiliary machine parts.

A skin treatment device is disclosed, which has a head capable of contacting a target site of a user, the head having an electrically driven cutter unit capable of cutting hair when in operation, and an action mechanism configured to apply a specific action to the target site of the user contacted by the cutter unit based on power supplied from a power source. The action mechanism includes, for example, a heating element that generates heat by flowing a direct current and / or a pair of electrodes that generate an electric stimulus.

This invention belongs to the field of high-voltage direct current (HVDC) transmission in power systems, specifically relating to a method, equipment, and medium for AC fault ride-through control at the sending end of a new energy source transmission system via a DRU-HVDC. When an AC fault occurs at the sending end, the grid-side converter of the new energy power station exits the active, reactive, and voltage loops, retains the inner current loop, and switches to maximum current output mode, locking the frequency to the rated value. Simultaneously, the receiving-end converter station exits the DC voltage outer loop, retains the inner current loop, and controls the DC current according to preset commands. During the fault duration, the diode rectifier station remains on and transmits maximum active power. After the fault is cleared, the output current of the new energy power station is reduced to the rated value, and then the power and voltage control loops are restored; the receiving-end converter station resumes constant DC voltage operation. This invention achieves maximum power control through preset commands. By controlling and switching between the new energy power station and the receiving-end converter station, the DRU is effectively maintained on, improving the active power transmission capacity and system recovery speed during faults.