39 results about "Inrush current limiter" patented technology

The invention relates to a reactor type short-circuit fault current limiter, which consists of reactors, a capacitor, a switch and lightning arresters. During the stable state of an electric grid, the current limiter works at a series resonance or series compensation status and is of low impedance; and after the electric grid is subjected to short-circuit fault, windings of the reactors are saturated due to overcurrent, or meanwhile, the change of the reactance of the reactors is controlled through closing the switch, so that the current limiter generates high impedance to realize fault current limiting. According to the current limiter, the automatic fault response is realized through the saturation of the reactors, and the current-limiting capacity is improved through circuit resonance; meanwhile, the manufacture cost of a system can be greatly lowered through the reasonable design of a current limiter structure; and the current limiter is strong in current-limiting capacity and has little influence on the electric grid, and the safety and the reliability of the operation of the electric grid are effectively improved.

Systems and methods for reducing inrush current into a component, such as a power converter (e.g., LED driver), which receives alternating current (AC) power from an AC power source (e.g., AC mains). The method may include pre-charging the input capacitance of a component or circuit for a determined period of time after closing of a control switch (e.g., photocontrol, contactor) using a capacitive load pre-charge circuit (e.g., resistor), and then shorting the capacitive load pre-charge circuit using a bidirectional AC switch coupled in parallel with the capacitive load pre-charge circuit after the determined period of time to selectively bypass the capacitive load pre-charge circuit. The bidirectional AC switch may include two source-connected metal oxide semiconductor field-effect transistors (MOSFETs) which have a very low “on resistance,” such that during steady-state operation, the protection circuit wastes very little power compared to conventional inrush protection circuits.

The invention discloses an inrush current limiter in a power supply, comprising a resistor, a field effect transistor and a gate driver. In a startup moment of the power supply, the gate driver does not start the field effect transistor so that an inrush current passes by the resistor and the resistance is limited to a safety value; and in a steady state of the power supply, the field effect transistor is already started by the gate driver so that a steady state current passes by the field effect transistor and the power dissipation is reduced by the field effect transistor to a minimum.

A device for limiting the inrush current component of a current provided by a supply to a load, the device including an impedance arranged between the supply and the load, a switch arranged to divert the current from the impedance, an inrush period timer connected to the supply and arranged to activate the switch after expiry of an inrush time period, the inrush time period being a time period beginning upon the supply becoming active such that current is available to be provided by the supply to the load and a reset circuit connected to the supply and the inrush period timer, the reset circuit arranged to deactivate the switch and reset the inrush period timer in response to the supply becoming inactive such that no current is available to be provided by the supply to the load.

The current limiter comprises a transformer, a parallel-resonant circuit and voltage detection and trigger circuit. Primary side of the transformer is cascaded into busbar of power network. The parallel-resonant circuit includes capacitor C, inductance L and thyristor K; inductance L cascaded to thyristor K is connected to capacitor C in parallel; two ends of capacitor C are connected to secondary ends of transformer. The current limiter with the said structure makes peak of short circuit current in power network be clipped off, and plays good effect of restraining whole short circuit current so as the prevent electrical equipments from impulsion of large electrical current. Utilization of the current limiter will reduce breaking capacity of breaker accordingly, bringing economic benefit. Structure of the invention is simple. thyristor K is only needed to close, but not needed of turnning off. closing time is less than 200ms so as to raise service life and reliability of thyristor.

The present invention relates to an inrush current limiter device (4) for limiting inrushing current to a connectable load (3) comprising: at least one switchable IGBT-based limiter unit (5) for selectively limiting the inrushing current, having at least one current limiting conductor element for a limited leading of current and at least an IGBT-based switch (Q2), whereby the IGBT-based switch (Q2) is used as well as a controlled current limiter and as a by-pass element, and at least one control device (7) for controlling the IGBT-based switch (Q2), whereby the control device (7) comprises at least one IGBT-based switch supply (6) and means for realizing (8) a smooth flank of an output signal at the selected conductor element.

The invention discloses a coordination and protection method and device of DC grid having a resistive type superconductive current limiter. The resistive type superconductive current limiter is put into a fault discharging loop. The method comprises the steps of obtaining a first impedance scope of the resistive type superconductive current limiter when the fault discharging loop reaches to the over-damping state; obtaining a second impedance scope of the resistive type superconductive current limiter when the fault current of the fault discharging loop begins to be attenuated; obtaining a third impedance scope of the resistive type superconductive current limiter based on the movement time of a master breaker in a DC breaker; obtaining the impedance value of the resistive type superconductive current limiter based on the first impedance scope, the second impedance scope, and the third impedance scope. The invention is advantageous in that through selecting the impedance value of the superconductive current limiter, the fault current can be effectively inhibited; it can be guaranteed that the DC breaker can reliably turn off the fault current, and the voltage and current stress ofa switch member can be reduced.

The invention discloses a method for calculating short-circuit current of a power network with a high-temperature superconducting current limiter, comprising the steps of establishing a short-circuitcurrent calculation method with a high-temperature superconducting current limiter and a high-temperature superconducting current limiter; Short-circuit current calculation model of FCL; inputting grid data and fault information into the model; simplifying the original network; constructing the admittance matrix of the simplified network; triangulating the admittance matrix; solving the voltage vector by the forward-backward substitution method; recalculating the impedance of the nonlinear branch according to the voltage vector, and updating the admittance matrix; calculating the sum of the currents of adjacent branches of the fault node, and further calculating the current deviation; judging whether the current deviation is less than a preset threshold value, and if so, completing the calculation; injecting the three-sequence currents of the fault node and the bus at both ends of the current limiter into the linear network, and solving the other bus voltages and branch currents. The technical proposal provided by the invention has the advantages of simple calculation, accurate result, strong practicability and the like, and can provide the basis for the safety and stability analysis of the electric network containing the high-temperature superconducting current limiter, the relay protection setting calculation and the like.

The invention provides a short-circuit fault limiter based on rectifier capacitor current nature commutation. The device is characterized by establishing a current limiter topological structure through theoretical analysis and pre-estimating feasibility, carrying out formula derivation to analyze in detail a current limiting process, and finally, carrying out simulation experiment to verify current limiting performance. The current limiting process of a current limiter can experience three stages: a short-circuit current normal rising stage before switch action, a brief commutation and voltage stabilization stage of a full-bridge rectifier capacitor charging circuit, and a current-limiting inductor complete involvement current-limiting stage. Normal operation of a power grid is not influenced when the current limiter does not act; after the current limiter acts, a short-circuit current value can be reduced greatly, and bus voltage drop is reduced obviously; a current-limiting inductor (L) and a charging capacitor (C) have an optimal coordination relationship, and thus an optimal current limiting effect can be achieved; and the device is low in harmonic content and has no hazard overvoltage.

The invention relates to a bridgeless buck-boost AC-to-DC converter. The converter is used for converting an AC input power source so as to provide a DC output power source with a positive electrode end and a negative electrode end on an output capacitor. The converter is characterized in that the first end of a first circuit is coupled with the first end of the AC input power source; the second end of the first circuit is coupled with a grounding end; the third end of the first circuit is coupled with the positive electrode end or the negative electrode end of the DC output power source; thefirst end of a second circuit is coupled with the second end of the AC input power source; the second end of the second circuit is coupled with the grounding end; the third end of the second circuit is coupled with the positive electrode end or the negative electrode end of the DC output power source; a third diode is coupled between the first end of the second circuit and the grounding end; and afourth diode is coupled between the first end of the first circuit and the grounding end. According to the bridgeless buck-boost AC-to-DC converter of the invention, conversion efficiency can be improved; a capacitor with low withstand voltage can be selected as the output end of the direct current output power source, a surge current limiter for starting up does not need to be added. The converter can be operated under a discontinuous conduction mode, a continuous conduction mode and a critical conduction mode.

The invention provides a capacitive commutation hybrid fault current limiter and a control method thereof. The capacitive commutation hybrid fault current limiter comprises an on-state low-loss branch, a current transfer branch and a current limiting branch. A semi-controlled device is simple in logic and economical and reliable. The hybrid fault current limiter is low in loss of the steady state,has a bidirectional current limiting capability and can effectively inhibit the short-circuit current of a DC grid; the locking time of a sub module IGBT is delayed to obtain enough time for motion of other protection devices; it is ensured that a current limiting resistor and a corresponding heat-dissipating device can be fully utilized to improve the current limiting effect. The control methodof the capacitive commutation hybrid fault current limiter comprises two conditions of the normal operation of the DC line where the current limiter is located or before detection of the generation offaults of the DC line where the current limiter is located or after detection of the generation of faults of the DC line where the capacitive commutation hybrid fault current limiter is located to achieve control for a resistance-inductive capacitor commutation hybrid current limiter.

A low-, medium-, or high-voltage voltage switchgear with a circuit breaker or circuit breakers is disclosed which can switch electrical equipment. To protect the switchgear, and the cirucuit breakers in the switchgear against so called spot welding under vacuum atmosphere, such as during a closing operation of a switchgear used, for example, for switching capacitive or inductive equipment or inductive or capacitive current network an inrush current limiter is placed electrically in line or in series with the current path of the circuit breaker.

A System and a method are disclosed for suppressing rush current noise in a power switch cell. The system comprises: a power switch (306) having an operational condition dependent upon the state of a control signal; and an inrush current limiter module (300) for outputting the control signal. The control signal transitions from a first value to an intermediate value and from the intermediate value to a second value, wherein the power switch is configured to operate in a low conductive (OFF) condition when the control signal has the first value, to operate in a high conductive (ON) condition when the control signal has the second value, and to operate in a moderately conductive condition when the control signal has the intermediate value. Therefore, when the power switch transitions from the OFF condition to the ON condition, the rush current noise may be reduced.

An inrush current limiter for electronic fuses detects the type of load connected to the electronic fuse at ignition. By detecting the type of load, the limiter prevents a large peak current from flowing through the fuse. When a short circuit occurs, the limiter ensures that the electronic fuse only operates once in linear mode.