Transformer Inductance Modulation for Interference-Resistant Communication

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Solution Overview

Problem

Existing methods for communication and power transmission in potentially explosive atmospheres, such as those used in process automation, face challenges with high susceptibility to interference and require expensive and space-consuming optocouplers, particularly in devices like capacitive or inductive fill level measuring devices and sensors.

Innovation Solution

A method and device utilizing a transformer with a primary-side and secondary-side coil, where the secondary-side inductance is modulated to transmit signals indirectly through a frequency change detectable on the primary side, enabling efficient and interference-resistant data transmission, with the secondary-side logic unit controlling the inductance by switching coil sections on and off, and the primary-side logic unit regulating the excitation frequency to match the resonant frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optocouplers are used for communication between primary side and secondary side, then communication reliability is improved, but device complexity and cost increase

Engineering Contradiction:
Improvecommunication reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines communication and power transmission functions into a single transformer interface. The secondary side coil serves dual purposes: it receives power from the primary side and simultaneously transmits communication signals back to the primary side through inductance modulation, eliminating the need for separate optocoupler components.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The transformer is designed to perform multiple functions: power transmission from primary to secondary side, and signal transmission from secondary to primary side. The secondary coil acts as both a power receiving element and a communication transmitting element, reducing overall system component count.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Loss of information

If amplitude modulation is used for signal transmission, then data transmission capability is improved, but susceptibility to interference increases

Engineering Contradiction:
Improvedata transmission capabilityVSAvoidsusceptibility to interference
Core Design Contradiction:
Loss of informationVSObject-affected harmful factors

Solution Approach 1:

Instead of modulating the amplitude or frequency of the excitation signal on the primary side, the patent inverts the approach by modulating the inductance of the secondary coil. This indirect frequency modulation method is less susceptible to interference from coupled signals while still achieving effective data transmission.

Inventive Principle:
Principle #13The other way round (Inversion)

3Object-affected harmful factors

If indirect frequency modulation via inductance modulation is used, then interference resistance is improved, but measurement precision requirements increase

Engineering Contradiction:
Improveinterference resistanceVSAvoidfrequency evaluation precision
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The primary side logic unit continuously monitors the resonant frequency of the oscillating circuit and adjusts the excitation frequency to maintain resonance. This feedback mechanism compensates for frequency shifts caused by inductance modulation, enabling precise detection of the modulated frequency changes while maintaining system stability.

Inventive Principle:
Principle #23Feedback

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 solution provides fault-free, efficient, and interference-immune data transmission, allowing for diagnostic monitoring of efficiency and potential maintenance alerts, while optimizing power transmission and reducing the need for additional components like optocouplers.

Implementation Method 1

a transformer (3), having a primary-side coil (31) and a secondary-side coil (32), which are part of an oscillating circuit

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the excitation frequency is regulated during the communication phase from the secondary unit to the primary unit in such a way that the excitation frequency always corresponds to the resonant frequency of the resonant circuit

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP2710745B1Method and apparatus for communication and powertransmission by means of a transformer
Publication Date: 2017.09.20 ENDRESS & HAUSER GMBH & CO KG
  • EP2710745B1 patent drawingFigure 1
  • EP2710745B1 patent drawingFigure 2a~2b

AI summary

The invention describes a method for communication by means of a transformer (3), which has at least one primary-side coil (31) and one secondary-side coil (32), which are part of a resonant circuit, wherein an excitation frequency is applied to the resonant circuit on the primary side. The invention is characterized by the fact that, in order to transmit a signal from the secondary side (II) to the primary side (I), the inductance of the secondary-side coil (32) is modulated. A corresponding apparatus for implementing the method is likewise claimed.