Gapped resonant current transformer

Abstract

A gapped resonant current transformer that has a pre-determined gap in a split-core. The invention eliminates the need for a magnetic flux shunt between the primary and secondary windings. Further, the sensitivity to the clamping force holding the two halves of the split-core is reduced as well as temperature effects on the core. Finally, excess heat is removed from overload (saturation) by circulating power back into the line.

Claims

1. A resonant current transformer comprising: a toroid core cut into a first and a second substantially identical halves wherein the first and the second substantially identical-halves are clamped together to form a pre-determined gapped split-core, the pre-determined gapped split-core having an installation clamping force requirement and two pre-determined gaps, the two pre-determined gaps of the split-core being filled with a nonmagnetic material including at least one of parylene, paint, or tape; a bus wire conducting a line current through the pre-determined gapped split-core causing a magnetic flux to be generated in the pre-determined gapped split-core; a first winding disposed around at least a portion of the first substantially identical half of the toroid core, the first winding inducing the magnetic flux to provide a voltage to a load; a second winding disposed around at least a portion of the second substantially identical half of the toroid core, the second winding including a capacitor to provide a resonate circuit at a line frequency of the bus wire; and at least one tap on the second winding, wherein the at least one tap is configured for optimizing a match between the line frequency and the resonate circuit to maximize output power.

2. The resonant current transformer of claim 1, wherein the nonmagnetic material placed within the two pre-determined gaps is parylene.

3. The resonant current transformer of claim 1, wherein the nonmagnetic material placed within the two pre-determined gaps is paint.

4. The resonant current transformer of claim 1, wherein the nonmagnetic material placed within the two pre-determined gaps is tape.

5. The resonant current transformer of claim 1, wherein the nonmagnetic material placed within the two pre-determined gaps protects the core interfaces from environmental corrosion.

6. The resonant current transformer of claim 1, wherein the first winding is remote from the second substantially identical half of the toroid core.

7. The resonant current transformer of claim 1, wherein the second winding is remote from the first substantially identical half of the toroid core.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an illustration of the prior art.

(2) FIG. 2 is an illustration of resonant current transformer having a gapped split-core in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

(3) Now referring to FIG. 1, this is an illustration of the prior art having a current transformer with a winding used to supply a small amount of power to a load. Toroid core 1 is cut into two halves 1 & 2 forming interfaces 4's. Bus wire 7 conducting line current 5 causes a magnetic flux to be generated in the core. Load winding 3 coupled to this magnetic flux provides voltage to output load 6.

(4) As shown in FIG. 2, there is an illustration of the present invention. This invention uses toroid core 1 cut in two halves where a nonmagnetic material 11 (such as parylene, paint, tape, etc.) of known thickness is placed in the two gaps to protect the core interfaces from environmental corrosion. The two halves are held in position by a clamp 13, 14. Bus wire 7 conducting line current 5 causing a magnetic flux to be generated in the core. Winding 3 coupled to this magnetic flux provides voltage to load 6. Added to this core and coupled to the magnetic flux is an auxiliary winding 10 of higher turn count. This winding is connected to a capacitor 9 to form a circuit resonate at the line frequency. FIG. 2 also shows taps 8 which allow selection during manufacturing of the best match between the line frequency and the circuit self-resonant frequency. This optimum match improves the maximum output power over the prior art.

(5) High voltage spikes may be destructive to the output load with a prior art device. Voltage slow rate of change across the invention capacitor 9 of FIG. 2 suppresses the voltage spikes or peeks.

(6) Although the present invention has been described with reference to certain preferred embodiments thereof, other versions are readily apparent to those of ordinary skill in the preferred embodiments contained herein.