An apparatus for reducing a magnetic coupling between a first electronic circuit and a second electronic circuit is provided. The apparatus includes a conductor loop enclosing the first electronic circuit or the second electronic circuit, and a tuning element coupled to the conductor loop. The conductor loop and the tuning element form a resonant circuit, wherein the tuning element is configured to adjust a resonance frequency of the resonant circuit to a frequency related to a frequency of a signal processed by the second electronic circuit.

Radio frequency (RF) filters configured to filter undesired signal components (e.g., noise and harmonics) from RF signals are disclosed. In one embodiment, an RF filter includes a first inductor coil having a first winding and a second inductor coil having a second winding and a third winding. The second winding of the second inductor coil is configured to have a first mutual magnetic coupling with the first winding, while the third winding of the second inductor coil is configured to have a second mutual magnetic coupling with the first winding. The second winding is connected to the third winding such that the first mutual magnetic coupling and the second mutual magnetic coupling are in opposition. In this manner, the first inductor coil and the second inductor coil may be provided in a compact arrangement while providing weak mutual magnetic coupling between the first inductor coil and the second inductor coil.

Air-core reactors for use with power transmission systems are disclosed. An example air-core reactor may include a main coil and an auxiliary coil. The main coil may include a first solenoid having a first diameter and a second solenoid having a second diameter, wherein the first diameter and the second diameter are different. The auxiliary coil may include a third solenoid. The first solenoid and the second solenoid may be arranged concentrically. The auxiliary coil may also be magnetically coupled to the main coil, and the auxiliary coil may be arranged concentric to the main coil.

A portable electric appliance with an energy saving device has an inductive capacitive reactor for low amperage use, acting as a multifaceted transformer with inductor and capacitor functionalities iteratively, includes: a stacked group of hollow centered continuous loop components sequentially arranged as follows: (i) a first ferrite toroidal component; (ii) a first separator component, being a doped separator component; (iii) a non-magnetic conductive metal toroidal component having a plurality of protrusions with notches between said protrusions; (iv) a second separator component, selected from the group consisting of doped and non-doped; (v) a second ferrite toroidal component. Another inductive capacitive reactor for industrial and commercial appliances with high amperage use has similar components as just stated and also has (v) a non-magnetic conductive metal toroidal component without protrusions; (vi) a third separator component; (vii) a second non-magnetic conductive metal toroidal component having a plurality of protrusions with notches between said protrusions, (viii) a fourth separator component; and (ix) a second ferrite toroidal component.

A transformer assembly comprises at least one transformer having a core. A primary winding is positioned on a first portion, a secondary winding is positioned on a second portion of the core. A neutral winding may be positioned on a third portion of the core. The secondary winding may receive an induced flux produced by an earth surface potential (ESP) via a system ground and/or receive an induced zero sequence flux produced by a non-linear load. The neutral winding may be configured to provide a mitigating flux to the secondary winding. The transformer may also be used as a filter for either GIC or triplen harmonic mitigation. In this case, the primary windings receive the zero sequence current (GIC or triplen harmonics) and the flux may be cancelled in neutral winding such that the zero sequence currents circulate between the zero sequence source and the filter transformer.

Methods and apparatus for flux cancellation includes first and second inductors. A system cam include first and second inductors and a layer of magnetic material disposed between the first inductor and the second inductor. In embodiments, when the inductors are driven with a respective oscillating current, at least a portion of magnetic flux generated by the first inductor is substantially canceled by at least a portion of magnetic flux generated by the second inductor in the layer of magnetic material.

An apparatus for reducing a magnetic coupling between a first electronic circuit and a second electronic circuit is provided. The apparatus includes a conductor loop enclosing the first electronic circuit or the second electronic circuit, and a tuning element coupled to the conductor loop. The conductor loop and the tuning element form a resonant circuit, wherein the tuning element is configured to adjust a resonance frequency of the resonant circuit to a frequency related to a frequency of a signal processed by the second electronic circuit.

Radio frequency (RF) filters configured to filter undesired signal components (e.g., noise and harmonics) from RF signals are disclosed. In one embodiment, an RF filter includes a first inductor coil having a first winding and a second inductor coil having a second winding and a third winding. The second winding of the second inductor coil is configured to have a first mutual magnetic coupling with the first winding, while the third winding of the second inductor coil is configured to have a second mutual magnetic coupling with the first winding. The second winding is connected to the third winding such that the first mutual magnetic coupling and the second mutual magnetic coupling are in opposition. In this manner, the first inductor coil and the second inductor coil may be provided in a compact arrangement while providing weak mutual magnetic coupling between the first inductor coil and the second inductor coil.

A device for reducing a magnetic unidirectional flux component in the core of a transformer includes at least one compensation winding, which is magnetically coupled to the core of the transformer, at least one switching unit in series with the compensation winding to feed a current into the compensation winding, and at least one current-limiting reactor in series with the compensation winding, wherein two switching units are connected in parallel with each other per current-limiting reactor and the current-limiting reactor comprises two windings, which can be connected either in series or in parallel with each other, in order to reduce the number of current-limiting reactors in comparison with conventional cascaded circuits.

Methods and apparatus for flux cancellation includes first and second inductors. A system cam include first and second inductors and a layer of magnetic material disposed between the first inductor and the second inductor. In embodiments, when the inductors are driven with a respective oscillating current, at least a portion of magnetic flux generated by the first inductor is substantially canceled by at least a portion of magnetic flux generated by the second inductor in the layer of magnetic material.