Capacitive Coupling for Galvanically Isolated Vehicle Systems

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Solution Overview

Problem

Existing vehicle electrical systems require complex and costly implementations to switch between active and idle states, particularly in multi-system vehicles, where wake-up signals need to be transmitted across isolated networks, often relying on bus systems or starter devices, and current solutions like optocouplers are unsuitable for high temperatures.

Innovation Solution

A capacitive coupling element connects two galvanically isolated vehicle electrical systems, allowing a signal generation unit in one system to transmit a wake-up signal to another, using a semiconductor switch to switch between idle and active states, eliminating the need for complex bus system coupling and optocouplers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If bus systems or starter devices are used to transmit wake-up signals across isolated networks, then wake-up signal transmission is achieved, but device complexity and implementation cost increase

Engineering Contradiction:
Improvewake-up signal transmissionVSAvoidbus system coupling
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary coupling device that electrically connects isolated electrical systems to enable wake-up signal transmission. This intermediary component bridges the gap between isolated networks without requiring complex bus system integration, thereby reducing device complexity while maintaining reliable signal transmission across galvanically isolated systems.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If optocouplers are used for signal transmission across isolated networks, then galvanic isolation is maintained, but they are unsuitable for high-temperature environments

Engineering Contradiction:
Improvegalvanic isolationVSAvoidhigh-temperature suitability
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent changes the physical parameters of the coupling device to withstand high-temperature environments. Instead of using optocouplers that fail at high temperatures, the invention employs a coupling device with modified electrical parameters and thermal characteristics that maintain galvanic isolation while operating reliably in high-temperature conditions typical of vehicle environments.

Inventive Principle:
Principle #35Parameter changes

3Speed

If electrical systems remain in active state to ensure immediate responsiveness, then system responsiveness is improved, but energy consumption increases and complete discharge of energy supply units occurs

Engineering Contradiction:
Improvesystem responsivenessVSAvoidenergy consumption
Core Design Contradiction:
SpeedVSUse of energy by moving object

Solution Approach 1:

The patent implements preliminary action by maintaining a weak electrical connection through the coupling device that allows wake-up signals to pass through even when systems are in idle state. This preliminary configuration enables immediate system activation upon receiving a wake-up signal without requiring continuous power supply, thus balancing responsiveness with energy conservation.

Inventive Principle:
Principle #10Preliminary action

4Loss of energy

If electrical loads are completely disconnected from power supply units in idle state to protect energy supply, then energy conservation is improved, but wake-up signal transmission becomes difficult

Engineering Contradiction:
Improveenergy conservationVSAvoidwake-up signal transmission
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The coupling device serves as an intermediary that maintains a signaling pathway between isolated electrical systems even when power connections are minimized in idle state. This intermediary component allows wake-up signals to traverse through the coupling device without requiring full power connection, enabling both energy conservation and reliable signal transmission.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 simplifies the activation of vehicle electrical systems by enabling indirect activation through capacitive coupling, reducing energy consumption in idle states and avoiding complete discharge of energy supply units, while being cost-effective and suitable for high-temperature environments.

Implementation Method 1

a capacitive coupling element (9) is provided by means of which the first vehicle electrical system (2) is capacitively coupled to the second vehicle electrical system (5) for signal transmission

Methodology Applied
Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentEP3003787B1Electrical system assembly for a motor vehicle
Publication Date: 2017.06.14 MAHLE INT GMBH
  • EP3003787B1 patent drawingFigure 1~2

AI summary

The invention relates to an electrical system assembly (1) for a motor vehicle, comprising a first electrical system (2), a second electrical system (5), which is galvanically isolated from the first electrical system (2) and which can be switched between an idle state and an active state, a capacitive coupling element (9), by means of which the first electrical system (2) is coupled capacitively to the second electrical system (5) for signal transmission, a signal-generating unit (13), which is provided in the first electrical system (2) and interacts with the coupling element (9) and by means of which an activation signal for activating the second electrical system (5) from the idle state can be provided at the coupling element (9) on the input side, and a signal-receiving unit (14), which is provided in the second electrical system (5) and which interacts with the coupling element (9) in such a way that the signal-receiving unit switches the second electrical system (5) from the idle state to the active state when the activation signal is provided at the coupling element (9) on the output side.