Pyrotechnic Disconnecting Device for High-Voltage Vehicle Systems
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Solution Overview
Problem
Conventional high-voltage vehicle electrical systems require complex and costly combinations of fuses and relays for reliable short-circuit shutdown, with high demands on tripping characteristics and significant cost disadvantages, especially in emergency situations like crashes where high currents are involved.
Innovation Solution
A high-voltage vehicle electrical system utilizing a pyrotechnic isolating device in series with a switching relay, where levitation occurs to reduce switching current and enable safe shutdown, allowing the pyrotechnic separator to disconnect the high-voltage battery from the electric motor without arcing, and a second switching relay for high-side protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional combination of fuse and relay is used for short-circuit shutdown, then reliable tripping can be achieved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent combines the fuse and relay into a single integrated disconnecting device where the relay coil generates a magnetic field that directly acts on a magnetic element in the fuse holder to trigger fuse separation. This merging eliminates the need for separate fuse and relay components while maintaining reliable short-circuit shutdown functionality.
Solution Approach 2:
The relay coil serves dual functions: it acts as both the switching coil for normal operation and the triggering mechanism for short-circuit protection. The magnetic field generated by the relay coil simultaneously controls both the relay contact and the fuse separation mechanism, making the system more versatile and reducing component count.
2Reliability
If a fuse and relay combination is used, then short-circuit protection is achieved, but the tripping characteristics require high precision and coordination
Solution Approach 1:
The system uses its own operational components (relay coil and magnetic field) to automatically trigger the protective function. During a short circuit, the relay coil generates an intensified magnetic field that automatically acts on the magnetic element to separate the fuse, eliminating the need for external coordination or additional sensing mechanisms.
Solution Approach 2:
The magnetic field acts as an intermediary between the relay coil and the fuse separation mechanism. The magnetic element serves as a mediator that translates the magnetic field intensity into mechanical separation of the fuse contacts, simplifying the coordination requirements by using a direct physical coupling mechanism.
3Reliability
If high current switching is required in emergency situations, then safe shutdown is achieved, but the cost and complexity of the switching device increase
Solution Approach 1:
The disconnecting device is segmented into two functional parts: the relay mechanism for control and the fuse element for high current interruption. The fuse holder is designed as a separate component that can be rapidly separated from the circuit when triggered, allowing the system to handle high currents without requiring the entire switching device to be rated for such currents.
Solution Approach 2:
The relay coil operates partially during normal operation and excessively during short circuits. During a short circuit, the coil generates a magnetic field intensity far exceeding normal operating levels, which is sufficient to trigger the fuse separation mechanism. This partial/excessive action allows the use of a smaller, less expensive relay coil that only needs to provide enough magnetic force during fault conditions.
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 reduces the switching voltage and current for the pyrotechnic isolator, enabling reliable and cost-effective emergency shutdowns by leveraging levitation in the low-side relay, ensuring safe disconnection of the high-voltage battery without the need for high current switching capabilities in the pyrotechnic device, thus reducing component costs and improving safety.
Implementation Method 1
levitation occurs to reduce switching current and enable safe shutdown
Data Source
Figure 1
AI summary
The invention relates to a high-voltage vehicle electrical system, comprising a high-voltage battery connection having a high-side connection contact and a low-side connection contact and comprising a high-voltage output having a high-side output contact and a low-side output contact. In order to reliably interrupt a short-circuit current by using levitation, at least one series circuit of a first switching relay and of a pyrotechnic disconnecting device is provided, which series circuit is arranged between the low-side connection contact and the low-side output contact.