Circuit Module Isolating Multi-Voltage Vehicle Subsystems
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Solution Overview
Problem
Multi-voltage vehicle electrical systems face issues with fault current resistance due to common ground connections, leading to potential damage from faulty operating voltage supplies, and existing solutions like galvanic isolation with transformers are costly and complex.
Innovation Solution
A circuit module is introduced that connects control signal paths to both ground terminals and operating voltages, allowing it to assume a blocking condition in response to faulty voltage supplies, preventing excessive fault currents and isolating subsystems with minimal additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic isolation with transformers is used to protect against faulty voltage supplies, then fault current resistance is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the protection function from the signal transmission path by using a separate monitoring circuit that independently detects voltage faults. This monitoring circuit is taken out from the main signal path and operates independently to detect faults and trigger isolation, thereby protecting the system without adding complexity to the primary signal transmission path.
Solution Approach 2:
The patent implements preliminary protection by pre-configuring isolation switches and monitoring circuits that detect faulty voltage conditions before they can cause damage. The monitoring circuit continuously checks voltage levels and is ready to activate isolation switches immediately upon detecting a fault, preventing fault currents from damaging components rather than reacting after damage occurs.
2Reliability
If monitoring modules and galvanic isolation are implemented, then fault current resistance is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs inexpensive protection elements such as fuse links and simple isolation switches that can be easily replaced rather than expensive complex isolation systems. These disposable protection elements provide effective fault current resistance at low cost, and when they fail, they can be quickly replaced without affecting the entire system architecture.
Solution Approach 2:
The patent introduces simple intermediary components like diodes and isolation switches that mediate between the multi-voltage subsystems. These intermediaries provide the necessary isolation and protection functions at minimal cost, acting as buffer elements that prevent direct fault current paths while maintaining system functionality during normal operation.
3Reliability
If separate ground terminals are used for different voltage subsystems, then fault current resistance is improved, but device complexity increases
Solution Approach 1:
The patent segments the ground connection structure by providing separate ground terminals for different voltage subsystems (e.g., 12V and 48V subsystems). This segmentation prevents fault currents from one subsystem from directly affecting other subsystems through common ground paths, while the isolated ground terminals can still be connected to a common reference point through high-impedance paths to maintain signal integrity.
Data Source
AI summary
A multi-voltage electrical system for a vehicle, which comprises a first subsystem with a transceiver and a second subsystem with a control unit, is provided. A first control signal path which couples a first signal output of the transceiver to a first signal input of the control unit is formed and arranged to transmit a first control signal from the first signal output to the first signal input. The first control signal path comprises a first circuit module which is formed to assume a blocking condition in response to a faulty operating voltage supply in the first subsystem and/or in the second subsystem, in which the transmission of the first control signal from the first signal output to the first signal input via the first control signal path is inhibited.