The invention comprises a harmonic filter apparatus and method of use thereof, the harmonic filter including a delta circuit comprising: (1) a first leg connecting a first apex to a second apex of the delta circuit; a second leg connecting the second apex to a third apex of the delta circuit; and a third leg connecting the third apex to the first apex and (2) a first electrical contactor and a second electrical contactor positioned within at least two of: the first leg, the second leg;

and the third leg. Optionally and preferably, each apex of the delta circuit is connected to individual phases of three phase power via respective inductor—coupled inductor pairs, where the harmonic filter magnetically isolates individual phases of the three phase power.

A power electronics system, comprising a first inverter configured to receive DC power from a power source and a second inverter configured to receive DC power from the power source is provided. The system includes a first output inductor connected in series to an output of the first inverter, a second output inductor connected in series to an output of the second inverter, a coupling inductor configured to receive current from the first output inductor and the second output inductor, and an AC power output.

A system for determining an operational state of an atmospheric pressure plasma. The system has a transformer for coupling power into the atmospheric pressure plasma, a current sampling circuit configured to sample at least one current pulse flowing through a primary winding of the transformer, and a programmed microprocessor configured to determine, from a waveform of the current pulse, the operational state of the atmospheric pressure plasma. The operational state is one of: a no plasma state, a plasma origination state indicative of an ignited arc expanding into a plasma by gas flow thereinto, and a plasma maintenance state indicative of the plasma being expanded.

A passive, current dependent inductivity (1) comprises a magnetic core (2), windings (3) and at least one bank air gap (4). A saturation region (5) made of magnetic material is arranged between the bank air gap (4) and the windings (3). A magnetic flux path (6) bifurcates into a first path (61) passing through the saturation region (5) and into a second path (62) passing through the bank air gap (4) and bypassing the saturation region (5). The magnetic resistance of the first path (61) is lower than the magnetic resistance of the second path (62) for winding currents below a first saturation current (7a) and whereby the magnetic resistance of the second path (62) is lower than the magnetic resistance of the first path (61) for winding currents above the first saturation current (7a) due to saturation of the saturation region.

A system for determining an operational state of an atmospheric pressure plasma. The system has a transformer for coupling power into the atmospheric pressure plasma, a current sampling circuit configured to sample at least one current pulse flowing through a primary winding of the transformer, and a programmed microprocessor configured to determine, from a waveform of the current pulse, the operational state of the atmospheric pressure plasma. The operational state is one of: a no plasma state, a plasma origination state indicative of an ignited arc expanding into a plasma by gas flow thereinto, and a plasma maintenance state indicative of the plasma being expanded.

A filter assembly includes a first self-inductance core, a second self-inductance core, a coupled inductor core, and a first plurality of inductor coil windings. Each of the first plurality of inductor coil windings has a series of first turns in a vertically stacked relation around the first self-inductance core, and a series of second turns in a vertically stacked relation around the first self-inductance core and the coupled inductor core. The filter assembly further includes a second plurality of inductor coil windings. Each of the second plurality of inductor coil windings has a series of first turns in a vertically stacked relation around the second self-inductance core, and a series of second turns in a vertically stacked relation around the second self-inductance core and the coupled inductor core.

A system for determining an operational state of an atmospheric pressure plasma. The system has a transformer for coupling power into the atmospheric pressure plasma, a current sampling circuit configured to sample at least one current pulse flowing through a primary winding of the transformer, and a programmed microprocessor configured to determine, from a waveform of the current pulse, the operational state of the atmospheric pressure plasma. The operational state is one of: a no plasma state, a plasma origination state indicative of an ignited arc expanding into a plasma by gas flow thereinto, and a plasma maintenance state indicative of the plasma being expanded.

An alternating current neutral and ground inductive electromagnetic rectification unit includes a first and second reactor connectable to a neutral and a ground of an existing circuit respectively. The first redactor includes a first pair of inductive coils, each coil disposed interior to a nonconductive tube. The second redactor includes a second pair of inductive coils, each coil also disposed interior to a nonconductive tube. The first pair of inductive coils are connected together in parallel, and also connected at opposing extremes terminating the neutral. The second pair of inductive coils are also connected in parallel, at opposing extremes of the ground. The first and second redactors are surrounded by an insulating matrix set within the housing. Once connected to the ground and neutral, the first and second redactors establish a magnetic field that redacts harmonic interference emerging on the neutral thereby increasing efficiency and power factor across the circuit.

A power electronics system, comprising a first inverter configured to receive DC power from a power source and a second inverter configured to receive DC power from the power source is provided. The system includes a first output inductor connected in series to an output of the first inverter, a second output inductor connected in series to an output of the second inverter, a coupling inductor configured to receive current from the first output inductor and the second output inductor, and an AC power output.

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.