Inductive Sensing Circuit With Remote Phase Error Correction

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Solution Overview

Problem

Existing signal conditioning circuits for active magnetic bearings face challenges in optimizing phase shifting for demodulation circuits, especially in automated and remote commissioning scenarios, due to manufacturing defects and build tolerances in inductive sensors.

Innovation Solution

The proposed solution involves an inductive sensing circuit with a signal generator, sensing arrangements in half bridge configurations, a correction signal circuit, and a demodulation circuit that adjusts and sums output signals to correct for errors, allowing for remote phase optimization and improved signal conditioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If RC filter networks are used for phase shifting in synchronous de-modulation circuits, then the phase can be matched when the system is in final installation with field cabling installed, but the adjustment is inconvenient for automated and remote commissioning

Engineering Contradiction:
Improvephase adjustment convenienceVSAvoidautomated commissioning capability
Core Design Contradiction:
Ease of operationVSExtent of automation

Solution Approach 1:

The patent replaces the traditional mechanical/manual adjustment of RC filter networks with an electronic phase shift register that can be controlled remotely. The phase shift is achieved through digital or electronic means rather than physical component adjustment, enabling automated commissioning while maintaining phase matching capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a dynamic phase adjustment mechanism that can be modified during operation or commissioning. The phase shift register allows the system to adapt its phase characteristics remotely, transforming a static RC network into a dynamically adjustable system that supports automated commissioning procedures.

Inventive Principle:
Principle #15Dynamics

2Ease of manufacture

If traditional inductive sensors with fixed RC filter networks are used, then the manufacturing is straightforward, but the performance is limited by manufacturing defects and build tolerances

Engineering Contradiction:
Improvesensor assembly simplicityVSAvoidinductive sensor performance consistency
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent implements a feedback mechanism where the system measures the actual phase characteristics of the inductive sensors and automatically adjusts the phase shift register compensations. This closed-loop approach compensates for manufacturing variations in RC networks and inductive sensor elements, improving performance consistency without requiring tighter manufacturing tolerances.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent allows adjustment of electrical parameters (phase shift values, scaling factors) after manufacturing to compensate for build tolerances. By making the system parameters可调 (adjustable), the patent decouples manufacturing precision requirements from operational performance, allowing standard manufacturing processes to produce high-performance systems.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If phase matching is performed during final installation, then the system achieves optimal performance, but the process requires on-site manual adjustment which is time-consuming

Engineering Contradiction:
Improvephase matching accuracyVSAvoidcommissioning time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent enables preliminary phase characterization and compensation value determination to be performed before final installation. The phase shift register can be pre-configured with compensation values based on factory measurements or theoretical calculations, eliminating the need for time-consuming on-site manual adjustment while maintaining phase matching accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements self-service commissioning where the system automatically determines optimal phase compensation values without requiring manual intervention. The phase shift register is configured automatically through software or automated testing procedures, allowing the system to self-optimize during commissioning and eliminating the need for skilled technicians to perform manual phase matching.

Inventive Principle:
Principle #25Self-service

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

This approach enhances the tolerance to manufacturing errors and impedance mismatches, maintaining an optimal signal-to-noise ratio and reducing the need for mechanical alignment, thus improving the performance and flexibility of active magnetic bearing systems.

Implementation Method 1

An inductive position sensor comprises a set of inductive elements with a variable gap fixed to the stator and cooperating with a reference ring, or 'target', integral with the rotor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a correction signal circuit configured to generate a correction signal, wherein the correction signal is an adjustably scaled version of the drive signal

Methodology Applied
Scientific EffectSignal scaling and phase adjustment:

Implementation Method 3

a summing circuit configured to sum an output signal of the two sets of one or more inductive sensing elements with the correction signal

Methodology Applied
Scientific EffectElectrical signal summation:

Data Source

PatentEP3705839B1Improved signal conditioning circuit for use with active magnetic bearings
Publication Date: 2022.12.28 WAUKESHA BEARINGS
  • EP3705839B1 patent drawingFigure 1
  • EP3705839B1 patent drawingFigure 2
  • EP3705839B1 patent drawingFigure 3

AI summary

There is provided an inductive sensing circuit, comprising a signal generator, configured to generate a drive signal; one or more sensing arrangements, each of the one or more sensing arrangements comprising: two sets of one or more inductive sensing elements, configured in a half bridge arrangement, the two sets of one or more inductive sensing elements driven by the drive signal; a correction signal circuit, configured to generate a correction signal, wherein the correction signal is an adjustably scaled version of the drive signal; and a summing circuit, configured to sum an output signal of the two sets of one or more inductive sensing elements with the correction signal; and a demodulation circuit, configured to demodulate an output of the summing circuit of each of the one or more sensing arrangements.