Electrostatic Shield for Current Sensing Coil Accuracy

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Solution Overview

Problem

Current sensing coils face inaccuracies due to electrostatic coupling with current carrying conductors, leading to significant measurement errors, which are difficult to correct and can change over time with component aging and environmental conditions.

Innovation Solution

An electrostatic shield is designed to be mounted over current sensing coils, featuring core shield portions that extend through the central opening to reduce or eliminate electrostatic coupling, improving measurement accuracy by shielding the coil from electrostatic interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If no electrostatic shield is used, then the device complexity is low, but measurement precision deteriorates due to electrostatic coupling errors

Engineering Contradiction:

Improvecurrent measurement accuracyVSAvoidshield structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The electrostatic shield is segmented into multiple functional portions: a first shield body with a first primary shield portion and a first core shield portion, and a second shield body with a second primary shield portion and a second core shield portion. This segmentation allows each portion to address specific electrostatic coupling paths independently, improving measurement precision while keeping each individual shield component relatively simple in structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The core shield portions extend through the central opening of the current sensing coil and are positioned within the coil's magnetic path. The first and second core shield portions overlap within the central opening, creating a nested shielding configuration that effectively blocks electrostatic coupling from both sides of the coil without requiring a completely enclosed complex structure.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If electrostatic shielding is added, then measurement precision improves by reducing electrostatic coupling, but device complexity increases due to additional shield components

Engineering Contradiction:

Improvemeasurement stability over timeVSAvoidnumber of shield components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The electrostatic shield structure serves multiple functions simultaneously: the primary shield portions provide electrostatic shielding for the coil windings, while the core shield portions extend through the central opening to shield the magnetic path and prevent electrostatic coupling at the core. This multi-functionality improves measurement stability without requiring separate components for each shielding function, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The first and second shield bodies are designed to be mounted on opposite sides of the current sensing coil, with their core shield portions overlapping within the central opening. This merging of shielding functions from both sides creates a comprehensive electrostatic shield that maintains measurement reliability over time, while the symmetrical design allows for standardized manufacturing and assembly.

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If core shield portions extend through the central opening, then electrostatic coupling is reduced, but the shield structure becomes more complex

Engineering Contradiction:

Improvecurrent sensing accuracyVSAvoidshield geometry complexity

Core Design Contradiction:

Measurement precisionVSShape

Solution Approach 1:

The core shield portions are positioned specifically within the central opening of the current sensing coil, where electrostatic coupling has the most significant impact on measurement accuracy. The first and second core shield portions overlap only in the critical region where they are needed to shield the magnetic path, rather than extending throughout the entire shield structure. This localized shielding approach improves current sensing accuracy while maintaining relatively simple overall shield geometry.

Inventive Principle:

Principle #3Local quality

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

The electrostatic shield significantly reduces measurement errors caused by electrostatic coupling, enhancing the accuracy of current sensing coils and maintaining improved accuracy even as components age or environmental conditions change.

Implementation Method 1

The electrostatic shield is configured to provide electrostatic shielding to a core of the current sensing coil in order to reduce or eliminate electrostatic coupling between the electrical conductor and the current sensing coil

Methodology Applied

Scientific EffectElectrostatic shielding: Electrostatics

Data Source

PatentUS11315725B2Current sensing coil electrostatic shielding

Publication Date: 2022.04.26 ANALOG DEVICES INT UNLTD CO

AI summary

The present disclosure relates to an electrostatic shield for providing electrostatic shielding for a current sensing coil. Current sensing coils are configured to enable the measurement of a current carried by an electrical conductor passing through a core of the current sensing coil. The electrostatic shield of the present disclosure is configured to provide electrostatic shielding to a core of the current sensing coil in order to reduce or eliminate electrostatic coupling between the electrical conductor and the current sensing coil, thereby improving the accuracy of current measurement that may be achieved by the current sensing coil.