US 12,716,919 B2 · Fiber optic current sensor controller

Abstract

An optical fiber current sensing controller module, where an optical transmitter is energized from a DC source and emits an optical field of calibrated intensity and wavelength to a linear polarizer which generates a reference signal which is then launched in alignment with the transmission axes of a polarization maintaining optical fiber link to a remote and passive fiber optic current sensor (FOCS), where the linearly polarized optical pulse traverses a complete circular path around an energized conductor and is subject to polarization plane rotation in proportion to the magnetic flux density with the integration equal to electric current magnitude according to Ampere's law, and the rotated polarized optical pulse is transmitted back to the optical fiber current sensing controller module via a return fiber optic cable, where the Stokes vector polarization parameters for the returned optical signal are calculated by splitting the elliptically polarized field into four components, passing these components through an analyzer comprised of a linear horizontal polarizer, a linear vertical polarizer, a linear polarizer with transmission axis set at 45 degrees, and a linear polarizer with transmission axis set at 135 degrees, respectively, and where the four separate outputs of the four fiber optic polarizing filters are connected respectively to four separate photodiodes which transduce each optical intensity to analog voltage outputs which are sampled by a digital signal processing chipset, where the Stokes vector parameters for the polarized optical signal are calculated directly from the digitally sampled array of optical intensity values transduced by the photodiodes, and the change in polarization state from which electrical current is measured is derived by comparing the initial linear polarization Stokes vector of the generated reference signal with the measured Stokes parameters of the elliptically polarized optical signal received from the analyzer, and where a sample of the generated polarized reference signal is measured at a photodiode to monitor online sensor network optical attenuation and reference signal power fluctuations.

An all fiber optic current sensor controller module, adapted to remotely interrogate an auxiliary fiber optic current sensor coil which is installed concentric with an electrical conductor, comprising:

an optical transmitter, comprised of a single mode fiber coupled distributed-feedback laser diode, with said optical transmitter connected to a module input power bus comprised of a voltage regulator chipset, with said power bus connected to an electrical energy storage device comprised of a battery, where said single mode laser transmits a continuous-wave optical reference signal which has a calibrated intensity magnitude and a calibrated center wavelength;
a fiber optic polarization generator, comprised of an all fiber linear polarizer which features a transmission axis, with an input of said generator spliced to an output of said optical transmitter, and with an output of said generator spliced to an integrated 1×2 polarization-maintaining fiber optic coupler which transmits a sample of a generated optical reference signal at a first output of said polarization maintaining 1×2 fiber coupler to a first fiber coupled photodiode, with said first photodiode connected to said power bus, and where a second output of said polarization maintaining 1×2 fiber coupler transmits said generated optical reference signal;
a module output port, which terminates said second output of said 1×2 polarization maintaining fiber coupler, where said output port is comprised of a bulkhead adapter configured to support an auxiliary patch-cord connection with said module output port;
a module input port, comprised of a bulkhead adapter configured to support an auxiliary patch-cord connection with said module input port;
a 1×4 polarization maintaining fiber optic star coupler, with an input of said star coupler connected to said module input port, and where said star coupler features four fiber optic outputs with each output featuring a respective polarization-maintaining birefringent axes;
a fiber optic polarization analyzer comprised of four all fiber linear polarizers with said all fiber linear polarizers featuring a respective transmission axis, with:
a first linear polarizer input spliced to a first polarization maintaining output of the fiber optic star coupler with a rotation angle of of 0° between said linear polarizer transmission axis and a horizontal axis of said polarization maintaining axes of said star coupler output;
a second linear polarizer input spliced to a second output of the star coupler with a rotation angle of 45° between said linear polarizer transmission axis and said horizontal axis of said polarization maintaining axes of said star coupler output;
a third linear polarizer input spliced to a third output of the star coupler with a rotation angle of 90° between said linear polarizer transmission axis and said horizontal axis of said polarization maintaining axes of said star coupler output;
a fourth linear polarizer input spliced to a fourth output of the star coupler with a rotation angle of 135° between said linear polarizer transmission axis and said horizontal axis of said polarization maintaining axes of said star coupler output:
where said analyzer transmits to a photodetector array comprising:
a second fiber coupled photodiode, connected to said module power bus, with an input spliced to an output of said first linear polarizer;
a third fiber coupled photodiode, connected to said module power bus, with an input spliced to an output of said second linear polarizer;
a fourth fiber coupled photodiode, connected to said module power bus, with an input spliced to an output of said third linear polarizer:
a fifth fiber coupled photodiode, connected to said module power bus, with an input spliced to an output of said fourth linear polarizer;
where said fiber coupled photodiodes produce a respective analog voltage output with a magnitude proportional to an incident optical intensity magnitude;
a data processing bus, comprised of a digital signal processing chipset with a plurality of single-ended analog to digital conversion inputs, where said digital signal processing chipset is connected to the module input power bus, and where a first, second, third, fourth, and fifth photodiode voltage output is connected to a respective analog to digital conversion input of said digital signal processing chipset, and where said digital signal processing chipset divides a respective difference of a third photodiode voltage output sampled value and a fifth photodiode voltage output sampled value by a respective difference of a second photodiode voltage output sampled value and a fourth photodiode voltage output sampled value to calculate an electrical current magnitude, and where said digital signal processing chipset subtracts a respective sum of said second photodiode voltage output sampled value and said fourth photodiode voltage output sampled value from a first photodiode voltage output sampled value to measure an attenuation magnitude of said optical reference signal;
and,
an integrated module display screen, connected to the power bus and data processing bus.

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Fiber optic current sensor controller

Life of this patent

Fiber optic current sensor controller

Life of this patent

Abstract

Claims1