Current Transducer Calibration Circuit and Magnetic Shield

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Solution Overview

Problem

Conventional current transducers have high tolerances in electrical and magnetic characteristics, leading to uncertainty in signal output and phase shifts, and traditional steel tape-wound shields are complex to manufacture, affecting noise shielding integrity.

Innovation Solution

A calibration circuit with variable resistors adjusts phase and sensitivity properties of current transducer outputs, and a solid-side shield composed of magnetically permeable annular rings provides improved noise shielding, fabricated to precise dimensions for consistent performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional current transducers are used with standard manufacturing processes, then manufacturing complexity is reduced, but measurement precision deteriorates due to high tolerances in electrical and magnetic characteristics

Engineering Contradiction:

Improvesignal output precisionVSAvoidcalibration circuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

A calibration circuit is introduced as an intermediary component between the current sensor and the output. This calibration circuit includes adjustable resistors that can be tuned to compensate for variations in the current sensor's electrical and magnetic characteristics, thereby improving measurement precision without requiring changes to the core sensor manufacturing process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The calibration circuit allows for adjustment of electrical parameters (resistance values) to compensate for manufacturing tolerances. By changing the resistance parameters in the calibration circuit, the overall measurement precision can be optimized for each individual current transducer unit.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If steel tape-wound shields are used to protect against noise, then shielding effectiveness is improved, but ease of manufacture deteriorates due to complex manufacturing processes

Engineering Contradiction:

Improvenoise shielding effectivenessVSAvoidshield manufacturing ease

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The traditional mechanical steel tape-winding process is replaced with a more straightforward shield construction method. The patent describes using pre-formed shield structures that can be easily assembled around the current sensor, eliminating the complex manual winding process while maintaining shielding effectiveness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The shield is divided into separate segments or sections that can be independently manufactured and then assembled around the current sensor. This segmentation simplifies the manufacturing process by allowing each shield section to be produced separately using simpler methods, while still providing comprehensive noise protection when assembled.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If steel tape-wound shields are used for noise protection, then shielding effectiveness is improved, but reliability deteriorates due to potential mishandling and integrity issues

Engineering Contradiction:

Improvenoise shielding effectivenessVSAvoidshield integrity

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The fragile mechanical steel tape-winding structure is replaced with more robust shield constructions that are less susceptible to damage during handling and assembly. The new shield design maintains electromagnetic shielding effectiveness while being mechanically more reliable and easier to handle without risk of compromising the shielding integrity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 calibration circuit ensures uniformity in current transducer measurements by adjusting phase and sensitivity, while the solid-side shield effectively protects against noise, enhancing data quality and manufacturing efficiency.

Implementation Method 1

a solid-side shield composed of magnetically permeable annular rings provides improved noise shielding

Methodology Applied

Scientific EffectMagnetic shielding: Magnetic Field

Implementation Method 2

A calibration circuit with variable resistors adjusts phase and sensitivity properties of current transducer outputs

Methodology Applied

Scientific EffectPhase adjustment:

Data Source

PatentUS9372249B2Systems and methods for calibrating phase and sensitivity of current transducers

Publication Date: 2016.06.21 BAKER HUGHES CO

AI summary

A circuit for calibrating a current transducer may include a first resistor and a second resistor, such that the first resistor and the second resistor may adjust a measurement output by a current sensor. The first resistor and the second resistor may adjust the measurement output by adjusting a phase of the measurement output and/or adjusting a sensitivity of the measurement output. The circuit may also include a first terminal and a second terminal, such that the first terminal may be electrically coupled to the first resistor and the second resistor. Here, the first terminal may receive the measurement output by the current sensor, and the second terminal may output the adjusted measurement output.