Energy Harvesting Current Transformer with Decoupled Measurement Modes

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Solution Overview

Problem

Current transformer devices used for energy harvesting and current measurements face accuracy issues due to non-linear elements affecting current readings and core saturation at high currents, making it difficult to measure fault currents accurately.

Innovation Solution

A current transformer device with a switching mechanism and microcontroller that bypasses energy harvesting circuit non-linear elements during demand and fault measurement modes, utilizing Hall sensors for accurate high-current readings and maintaining energy harvesting capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If energy harvesting circuit with non-linear elements is conductively coupled to current transformer, then energy harvesting capability is improved, but current measurement accuracy deteriorates

Engineering Contradiction:

Improveenergy harvesting capabilityVSAvoidcurrent measurement accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent divides the operational modes into distinct segments: normal operation mode where energy harvesting is active, and measurement modes (demand and fault) where harvesting is decoupled. This segmentation allows the system to optimize for either energy harvesting or measurement accuracy depending on operational requirements, eliminating the interference between non-linear harvesting elements and measurement circuits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic switching between different operational states through a microcontroller-controlled switch. The system dynamically transitions between normal operation mode (with harvesting) and measurement modes (without harvesting) based on measurement requirements. This dynamic reconfiguration allows the same hardware to serve dual purposes without compromising either function's performance.

Inventive Principle:

Principle #15Dynamics

2Device complexity

If same current transformer is used for both energy harvesting and current measurement, then device complexity is reduced, but measurement precision deteriorates at high currents

Engineering Contradiction:

Improvedevice complexityVSAvoidhigh current measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent employs periodic switching between energy harvesting operation and measurement operation. During measurement intervals (both demand and fault modes), the system temporarily disconnects the non-linear harvesting elements and activates measurement-optimized circuitry. This periodic alternation allows a single current transformer to serve both purposes accurately, as the measurement-critical path is isolated from harvesting non-linearities during measurement windows.

Inventive Principle:

Principle #19Periodic action

3Use of energy by moving object

If non-linear elements are present in energy harvesting circuit, then energy harvesting efficiency is improved, but measurement precision deteriorates

Engineering Contradiction:

Improveenergy harvesting efficiencyVSAvoidcurrent reading accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent extracts or removes the non-linear harvesting elements from the measurement signal path during measurement operations. The switch circuit physically disconnects the non-linear harvesting components when measurement modes are activated, ensuring that only linear, measurement-optimized circuitry remains in the signal path. This extraction eliminates the source of measurement distortion while preserving harvesting functionality during normal operation.

Inventive Principle:

Principle #2Taking out (Extraction)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enhances measurement accuracy by decoupling non-linear elements during measurements, allowing for precise current readings across a wide range and detecting high fault currents, while maintaining energy harvesting functionality.

Implementation Method 1

at least one Hall sensor coupled to the microcontroller, wherein the microcontroller controls the switching device to couple and decouple the energy harvesting circuit from the device circuit, and controls at least one Hall sensor coupled to the microcontroller

Methodology Applied

Scientific EffectHall effect: Hall Effect

Implementation Method 2

a current transformer and a device circuit coupled to the current transformer

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS9379556B2Systems and methods for energy harvesting and current and voltage measurements

Publication Date: 2016.06.28 EATON INTELLIGENT POWER LTD

AI summary

A harvesting and measurement device is operable in at least a normal operation mode, a demand measurement mode, and a fault measurement mode. In the normal operation mode, the device is able to harvest energy from an associated power line and monitor current and voltage conditions through a lower power circuit. In the demand measurement mode, harvesting elements of the circuit are disabled so as not to interfere with accuracy of demand current measurements. In the fault measurement mode, one or more Hall sensors are activated such that high currents can be accurately measured.