Vehicle Power Branch Isolation With Redundant Overcurrent Protection
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Solution Overview
Problem
On-board electrical systems for motor vehicles, especially electrically powered ones, face challenges in ensuring reliable independent power supply to safety-relevant components due to the lack of effective isolation and protection against faults and overcurrents, which can lead to consequential damage and unreliable operation.
Innovation Solution
The implementation of a circuit breaker arrangement with a controllable switch unit, overcurrent protection, and monitoring unit that isolates two electrical system branches via a positive voltage-side current path, ensuring reliable power supply and protection by switching states during rest and operating modes, and diagnosing faults without additional power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple disconnect switch arrangement is used to isolate branches, then the device complexity is reduced, but the reliability and protection against overcurrents is insufficient
Solution Approach 1:
The disconnect switch arrangement is segmented into multiple functional units: a first controllable switch unit for normal disconnection, a second controllable switch unit for backup protection, and an overcurrent protection unit for fault isolation. This segmentation allows each unit to perform its specific function reliably while maintaining overall system reliability without excessive complexity.
Solution Approach 2:
The overcurrent protection unit is integrated into the disconnect switch arrangement to provide beforehand protection against overcurrents and faults. This preventive measure ensures that if an overcurrent occurs, the protection unit automatically interrupts the current flow, preventing damage to other branches and maintaining system reliability without requiring complex external protection circuits.
2Ease of operation
If the first switch unit is kept closed during standby mode, then current can flow freely, but overcurrent damage can occur without proper protection
Solution Approach 1:
The overcurrent protection unit acts as an intermediary between the first and second switch units. During standby mode, when the first switch unit is closed to allow current flow, the overcurrent protection unit monitors the current and automatically interrupts it if overcurrent conditions occur, thus protecting the system without requiring complex control logic.
Solution Approach 2:
The disconnect switch arrangement is designed to be self-protecting through the integrated overcurrent protection unit. The system automatically detects and responds to overcurrent conditions without requiring external intervention or complex control systems, maintaining ease of operation while providing robust protection.
3Reliability
If additional protection units are added to the disconnect switch arrangement, then the protection level increases, but the device complexity and cost increase
Solution Approach 1:
The overcurrent protection unit is merged directly into the disconnect switch arrangement, combining the disconnection function with the overcurrent protection function in a single integrated component. This merging approach provides enhanced protection against faults while avoiding the complexity and cost of separate external protection circuits, as the protection functionality is built-in rather than added as a separate system.
Data Source
Figure 1
AI summary
Disclosed is an on-board electrical system (BZ) comprising: - at least two on-board electrical system branches (BZ2, BZ3); - a disconnect switch arrangement (TS) between the two on-board electrical system branches (BZ2, BZ3); - wherein the disconnect switch arrangement (TS) comprises a first controllable switch unit (T1) and a series connection (SS) of a second controllable switch unit (T2) and an overcurrent protection unit (S); - wherein the first switch unit and the series connection are electrically connected in parallel to each other between the two on-board electrical system branches (BZ2, BZ3); - a control unit (SE) configured to switch the first switch unit (T1) to an open, current-blocking switching state or to maintain it in this current-blocking switching state, and to switch the second switch unit (T2) to a closed, current-conducting switching state or to maintain it in this current-conducting switching state, in a standby mode of the on-board electrical system (BZ).Furthermore, a motor vehicle with the aforementioned on-board electrical system (BZ) is described.