HV Control Line Monitoring for Safe EV Battery Disconnect
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Solution Overview
Problem
In high-voltage onboard electrical systems of electric or hybrid vehicles, safe disconnection of power during accidents or servicing is compromised by faults in the control line, leading to potential short circuits and unsafe voltage conditions, as existing systems rely on a single control line for all components, which can result in unintended power supply and safety reactions suppression.
Innovation Solution
A monitoring apparatus with a switchgear that includes a relay series-coupled to the pyrotechnic safety device, allowing controlled interruption of the control line, enabling safe disconnection of high-voltage paths and preventing power supply to high-voltage components, with additional safety features like diodes and fuses to prevent backfeeding and short-circuit protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single control line (KL30C) is used for all contactors and safety lines, then device complexity is reduced, but reliability deteriorates because faults in one line can compromise the entire system's safe disconnection capability
Solution Approach 1:
The control line is segmented into multiple independent control lines (first control line and second control line) that can be independently monitored and controlled. This allows the system to maintain safe disconnection capability even if one control line fails, as the other line can still trigger the pyrotechnic safety device. The segmentation resolves the contradiction by trading increased device complexity for significantly improved reliability.
2Ease of operation
If all contactors are routed via a single KL30C signal, then ease of operation is improved, but safety deteriorates because contactors cannot be individually controlled during servicing, potentially leading to unintended power supply
Solution Approach 1:
Contactors are divided into different groups controlled by separate control lines. The first control line controls contactors that should remain open during servicing, while the second control line controls contactors that may need to be closed for servicing operations. This segmentation enables individual control of contactors while maintaining safety thresholds, resolving the contradiction between ease of operation and safety.
Solution Approach 2:
Different control lines have different control characteristics tailored to their specific functions. The first control line is configured for safety-critical disconnection, while the second control line allows controlled activation during servicing. This local differentiation in control quality enables both ease of operation and safety compliance simultaneously.
3Reliability
If the control line is interrupted to switch off high-voltage components, then safety is improved, but productivity deteriorates because the disconnection is irreversible and prevents further system operation
Solution Approach 1:
The control line switchgear is designed to be dynamically controllable, allowing it to switch between connected and disconnected states based on system conditions. The electronic computing device can control the switchgear to disconnect the control line when safety threats are detected, while also enabling reconnection when conditions are safe. This dynamic control resolves the contradiction by making disconnection reversible and conditional, maintaining both safety and productivity.
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
Ensures safe and controlled disconnection of high-voltage components during accidents or servicing, preventing short circuits and unsafe voltage conditions, while allowing reversible disconnection and safe operation of the electrical system, enhancing overall safety and reliability.
Implementation Method 1
a pyrotechnic safety device, wherein in the event of an interruption of the control line, the switchgear opens the high-voltage positive path and the high-voltage negative path
Data Source
AI summary
A monitoring apparatus of an onboard electrical system of an at least partially electrically operated motor vehicle. A switchgear is configured to switch a high-voltage positive path and a high-voltage negative path of an electrical energy storage device of the onboard electrical system. The switchgear has a control line which is coupled to a pyrotechnic safety device. In an event of an interruption of the control line, the switchgear opens the high-voltage positive path and the high-voltage negative path. A control line switchgear is series-coupled in the control line to the pyrotechnic safety device. The control line switchgear interrupts the control line as a function of a control signal of an electronic computing device. The electronic computing device is configured to check a voltage potential in the control line using the control line switchgear before the electrical energy storage device is connected to the onboard electrical system.