Galvanic Isolation Interface for Analog Signal Transmission

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Solution Overview

Problem

Existing electrical interfaces for galvanic isolation of analog signals require complex and costly designs with multiple isolation components, making them bulky and inefficient for applications like pump units, which need to transmit both analog and digital signals with a single isolation method.

Innovation Solution

An electrical interface using a transformer with a first and second winding, where the second winding is subjected to an alternating voltage by a changing resistor circuit, allowing the transmission of constant analog signals through a transformer by modifying its inductance based on the input signal's time profile, thus eliminating the need for additional isolation components and pre-processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple galvanic isolation components and pre-processing circuits are used to transmit analog signals, then signal transmission reliability is improved, but device complexity and installation space increase

Engineering Contradiction:
Improvesignal transmission reliabilityVSAvoidinterface complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions (galvanic isolation, signal transmission, and measurement) into a single transformer component. The transformer's first winding provides galvanic isolation while the second winding with the resistor circuit enables analog signal transmission, eliminating the need for separate isolation components and pre-processing circuits.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The transformer is designed to perform multiple functions simultaneously: it provides galvanic isolation between circuits, transmits analog input signals through magnetic coupling, and enables measurement of the transmitted signal through its second winding. This multi-functionality reduces the overall number of components needed in the interface circuit.

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

2Reliability

If multiple galvanic isolation components are used, then electrical fault protection is improved, but installation space increases

Engineering Contradiction:
Improvefault protectionVSAvoidinstallation space
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges multiple isolation functions into a single transformer structure. The magnetic circuit of the transformer provides galvanic isolation while housing both windings, thereby protecting against electrical faults without requiring additional isolation components that would increase installation space.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If analog signals are pre-processed and digitized before transmission, then signal transmission accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvesignal transmission accuracyVSAvoidpre-processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential measurement function from complex pre-processing circuits and implements it through a simple resistor circuit connected to the transformer's second winding. By measuring the voltage across the resistor, the system obtains accurate analog signal information without requiring digitization or complex pre-processing.

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

This solution enables the galvanically isolated transmission of analog signals with a single isolation component, reducing installation space and complexity while maintaining accurate signal transmission, suitable for applications like centrifugal pump units.

Implementation Method 1

a transformer (7) with a first and a second winding, which are coupled to one another in a magnetic circuit

Methodology Applied
Scientific EffectMagnetic coupling: Electromagnetic Induction

Implementation Method 2

the measuring circuit (10) is set up to apply an alternating voltage to the second winding (L2) by changing the resistor circuit (20)

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3499247B1Galvanically separate interface and method for transmitting analogue signals through this interface
Publication Date: 2020.02.26 WILO SE
  • EP3499247B1 patent drawingFigure 1
  • EP3499247B1 patent drawingFigure 2~3
  • EP3499247B1 patent drawingFigure 4

AI summary

The invention relates to an electrical interface (2) of a pump unit (1) for the galvanically isolated transmission of an analog input signal to a device electronics (9), comprising a transformer (7) with a first winding (L1) and a second winding (L2) coupled to the first winding (L1) in a magnetic circuit. The invention also relates to a corresponding method. The first winding (L1) is connected to an interface input (4) for applying the input signal, and the second winding (L2) is connected to a variable resistor circuit of a measuring circuit (10), which is configured to apply a changing voltage to the second winding (L2) by changing the resistor circuit, to determine a time interval from the time course of at least one electrical quantity of the resistor circuit, and to determine the magnitude of the input signal from this.