A core has first to third magnetic leg portions. First and second windings wound on the first and second magnetic leg portions, respectively, are connected in series to constitute a first reactor. A third winding wound on the third magnetic leg portion constitutes a second reactor. A magnetic field produced from the first reactor and a magnetic field produced from the second reactor reinforce each other in the second magnetic leg portion, but weaken each other in the first magnetic leg portion. In accordance with increase in currents, the operation of the first and second reactors changes from a magnetically uncoupled mode in which the first and second reactors operate in a magnetically non-interfering state to a magnetically coupled mode in which the first and second reactors operate in a magnetically interfering state.

An inductor includes discrete magnetic core pieces fabricated from different magnetic materials having different magnetic properties. An inverted U-section conductive coil includes a top section and first and second legs to establish a surface mount connection to a circuit board, and the discrete magnetic core pieces are assembled around the inverted U-section conductive coil. The first and second discrete magnetic core pieces are operable to reach magnetic saturation at respectively different current loads applied to the coil when the circuit board is energized, imparting multiple steps of inductance rolloff response to a range of current loads.

Distributed series reactance modules and active impedance injection modules that are adapted to operating with electric power transmission lines over a wide range of transmission voltages are disclosed. Key elements include a virtual ground, an enclosure that acts as a Faraday shield, radio frequency or microwave control methods and the use of corona rings.

A variable coupled inductor comprises a first core having a first protrusion, a second protrusion, a third protrusion, a first conducting-wire groove and a second conducting-wire groove on the top surface of the first core, wherein the second protrusion is disposed between the first protrusion and the third protrusion, wherein a first conducting wire is disposed in the first conducting-wire groove, and a second conducting wire is disposed in the second conducting-wire groove, wherein a second core, disposed over the first core, wherein a magnetic structure is integrally formed with the second core and protruded on the bottom surface of the second core, wherein the bottom surface of the magnetic structure is located over the top surface of the second protrusion.

A converter device comprising a converter and a coil arrangement that contains a number of coils. The coil arrangement has a plurality of interconnected coils. Toroidal cores of a soft magnetic nanocrystalline material are associated with each of said coils. A coupling toroidal core (11) is provided with a core opening (12) through which at least two windings (8, 9) of different coils can be guided and mounted. At least the winding of one coil is guided and mounted through a core opening of an individual toroidal core (13, 14). An open/closed-loop control device is provided with a current controller that acts on the coils such that direct current components are compensated by currents flowing through the windings of the coils.

A fault current limiter, including: an inductor, a direct current circuit breaker, a shunt resistor, and a first fixed resistor. The inductor includes wound superconducting wires. The direct current circuit breaker and the inductor are connected in series to form a series branch. The shunt resistor is connected in parallel to the series branch. The first fixed resistor is connected in parallel to the direct current circuit breaker.

A fault current limiter, including: two inductors, a direct current circuit breaker, a shunt resistor, a first fixed resistor, and metal oxide arresters. The two inductors include wound superconducting wires. The inductors have identical number of windings and identical structure. Magnetic fluxes of the inductors are forward coupled, and the inductors are connected in parallel to form a superconducting inductor structure. The direct current circuit breaker and the superconducting inductor structure are connected in series to form a series branch. The shunt resistor is connected in parallel to the series branch. The first fixed resistor is connected in parallel to the direct current circuit breaker. The metal oxide arresters are two in number, and are connected to two ends of the inductors in parallel.

An inductor includes a magnetic core composed of a magnetic material having variable permeability characteristics based on at least one of design parameters or operational parameters of the inductor that includes one or more air gaps. A coil is wound through the one or more air gaps and is configured to be excited by an electric current.

A fault current limiter (FCL) has a core structure with a first and second magnetisable core members and an AC magnetomotive force source configured to generate a varying magnetic flux in at least a portion of the first and second magnetisable core members. Static magnetomotive force sources being positioned to provide a magnetic circuit within at least part of the magnetisable core members. The FCL may have a ring core structure and the static magnetomotive force sources may include a mitred or tapered joint interface with the core member.

A variable coupled inductor includes a first core, two conducting wires, a second core and a magnetic structure. The first core includes two first protruding portions, a second protruding portion and two grooves, wherein the second protruding portion is located between the two first protruding portions and each of the grooves is located between one of the first protruding portions and the second protruding portion. Each of the conducting wires is disposed in one of the grooves. The second core is disposed on the first core. A first gap is formed between each of the first protruding portions and the second core and a second gap is formed between the second protruding portion and the second core. The magnetic structure is disposed between the second protruding portion and the second core and distributed symmetrically with respect to a centerline of the second protruding portion.