Automotive Data Transceiver Common-Mode Interference Compensation

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Solution Overview

Problem

The increasing number of electrical and electronic systems in automobiles, particularly with the adoption of the IEEE 1000Base-T1 standard, leads to significant electromagnetic interference (EMI) due to mutual interference, which reduces the signal-to-noise ratio and increases bit-error rates, posing a challenge in maintaining reliable data transmission within the limited automotive space.

Innovation Solution

A data transmission system with a control unit featuring a two-wire line for differential signal transmission, incorporating a measuring circuit to detect common-mode components, an error correction circuit to generate correction signals, and a compensation circuit to correct received signals, integrated into a single chip receiver, along with a common-mode filter to mitigate interference, allowing for comprehensive interference compensation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the IEEE 1000Base-T1 standard is adopted for high-bandwidth data transmission, then data transmission speed is improved, but electromagnetic interference increases

Engineering Contradiction:
Improvedata transmission speedVSAvoidelectromagnetic interference
Core Design Contradiction:
SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the receiver measures the common-mode component of the received signal and feeds back correction information to the transmitter. The transmitter then adjusts its transmission signal based on this feedback to compensate for EMI effects. This closed-loop feedback system enables the high-speed 1000Base-T1 transmission to maintain signal integrity despite electromagnetic interference from other automotive systems.

Inventive Principle:
Principle #23Feedback

2Adaptability or versatility

If multiple electrical and electronic systems are placed in limited automotive space, then system functionality is improved, but electromagnetic interference increases

Engineering Contradiction:
Improvesystem functionalityVSAvoidelectromagnetic interference
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The feedback mechanism measures the actual common-mode interference present in the transmission channel and generates correction signals accordingly. This allows the system to adapt to the specific EMI environment created by multiple electronic systems in the automotive platform, maintaining reliable communication without requiring physical isolation or shielding of each system.

Inventive Principle:
Principle #23Feedback

3Object-affected harmful factors

If complex input filters are used for common-mode suppression, then electromagnetic interference is reduced, but device complexity increases

Engineering Contradiction:
Improvecommon-mode interferenceVSAvoidfilter complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of using complex passive filters at the input, the patent employs an active feedback mechanism that digitally measures and corrects common-mode interference. This software-based correction approach replaces complex hardware filtering, reducing component count and simplifying the receiver design while maintaining effective EMI suppression.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical/electrical approach of complex input filtering with a signal processing approach. The common-mode correction is achieved through digital signal processing and mathematical compensation rather than physical filter components, substituting electronic/mechanical filtering with computational methods.

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

4Productivity

If the bandwidth is increased to 350-500MHz for 1000Base-T1 standard, then data transmission capacity is improved, but signal-to-noise ratio decreases

Engineering Contradiction:
Improvedata transmission capacityVSAvoidsignal-to-noise ratio
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The feedback mechanism measures the common-mode component across the entire 350-500MHz bandwidth and generates frequency-dependent correction signals. This allows the system to maintain signal-to-noise ratio across the wide bandwidth by actively compensating for EMI effects at each frequency, enabling high-capacity data transmission without sacrificing signal quality.

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 approach effectively reduces electromagnetic interference by correcting differential signal errors caused by common-mode components, enhancing signal integrity and reducing bit-error rates in high-bandwidth automotive data transmission systems like Ethernet, even in the presence of large interference signals from engine switching operations.

Implementation Method 1

A measuring circuit 10 is arranged upstream of the common-mode filter 4 and detects the common-mode component

Methodology Applied
Scientific EffectCommon-mode interference: Electromagnetic Induction

Implementation Method 2

a common-mode filter (4) arranged downstream of the measuring circuit (10), configured to remove the common-mode component from the useful signal

Methodology Applied
Scientific EffectCommon-mode filtering: Electromagnetic Induction

Implementation Method 3

A useful signal is transmitted as a differential signal between the first and second control units via the two-wire line

Methodology Applied
Scientific EffectDifferential signaling: Electrical Resistance

Data Source

PatentEP3420645B1Data transfer system, control unit, and method for transferring data
Publication Date: 2023.08.23 VOLKSWAGEN AG
  • EP3420645B1 patent drawingFigure 1
  • EP3420645B1 patent drawingFigure 2
  • EP3420645B1 patent drawingFigure 3

AI summary

The invention relates to a data transfer system (1), wherein the data transfer system (1) has a first control unit (2) and a second control unit (3), wherein the transfer path between the two control signals (2, 3) is formed at least partially by a two-wire cable (5), by means of which a useful signal is transferred as a difference signal between the first control unit (2) and the second control unit (3), wherein the first control unit (2) has a transceiver (9) and the second control unit (3) has a receiver (8), wherein a measurement circuit (10) designed to measure a common-mode component in the useful signal is arranged before the receiver (8) of the second control unit (3), wherein an error correction circuit (11) is provided, which is designed in such a way that a correction signal (F) is produced in accordance with the measured common-mode component, wherein a compensation circuit (12) is arranged after the receiver (8), wherein the compensation circuit (12) is designed in such a way that the useful signal received by the receiver (8) is corrected by means of the correction signal (F). The invention further relates to a control unit and to a method for transferring data.