Capacitor-Backed Activating Current for HV Battery Disconnects
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Solution Overview
Problem
In electric or hybrid vehicles, the high voltage battery must be safely disconnected from the motor and other electric parts during accidents without unintended reconnection, but existing disconnecting devices face reliability issues, particularly with pyrotechnic ignition elements failing due to abrupt battery disconnection during crashes, leading to potential fires and explosions.
Innovation Solution
A power source with a capacitor-based redundant power system and diagnostic monitoring for the pyrotechnic ignition device, providing alternative current paths to ensure reliable activation of the disconnecting device, even when the primary power source is unavailable, and continuously monitoring the health of the pyrotechnic ignition element to prevent such failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single power source is used to activate the pyrotechnic ignition element, then the device complexity is reduced, but the reliability decreases due to potential power source failure during accidents
Solution Approach 1:
The capacitor is pre-charged to a high voltage level during normal operation through the charging circuit. This preliminary energy storage ensures that when an accident occurs and the battery is disconnected, the capacitor can immediately provide the necessary activating current to the pyrotechnic ignition element without requiring the battery to remain connected.
Solution Approach 2:
The capacitor serves as a backup energy reservoir that cushions against the failure scenario where the battery disconnects during an accident. By having this pre-charged energy reserve, the system ensures continuous operation of the safety function even when the primary power source becomes unavailable.
2Object-affected harmful factors
If the battery is disconnected during an accident to ensure safety, then the harmful effects are reduced, but the risk of unintended reconnection increases without a reliable disconnecting device
Solution Approach 1:
The capacitor acts as an intermediary energy source between the battery and the pyrotechnic ignition element. It receives energy from the battery during normal operation and can independently activate the ignition element when needed, ensuring the disconnecting device functions reliably even when the battery is disconnected or unavailable.
Solution Approach 2:
The capacitor is pre-charged during normal operation to ensure immediate activation capability of the disconnecting device when an accident occurs, eliminating delays and ensuring the safety function activates reliably without depending on continuous battery connection.
3Speed
If a pyrotechnic ignition element is used for disconnection, then the speed of disconnection is increased, but the reliability decreases due to potential failure of the ignition element to activate
Solution Approach 1:
The capacitor is continuously maintained at a high voltage level through the charging circuit during normal operation, ensuring that when the pyrotechnic ignition element needs to be activated, the full activating current is immediately available without delay or dependence on battery connection status.
Solution Approach 2:
The capacitor provides a cushion against activation failure by ensuring sufficient energy is stored and available. This pre-charged energy reserve guarantees that even if the battery disconnects or there are voltage drops, the pyrotechnic ignition element receives adequate current for reliable activation.
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
The solution enhances the reliability and safety of disconnecting high-voltage batteries by providing a redundant power source and health monitoring, preventing unintended reconnections and reducing the risk of fires and explosions during vehicle crashes.
Implementation Method 1
a capacitor (16) having a first electrode (16a) coupled to an output of the charging circuit (15)
Implementation Method 2
The disconnecting device (11) may comprise a pyrotechnic ignition element (12)
Data Source
AI summary
A power source and method for providing an activating current a power source comprises an input terminal, a charging circuit having an input coupled to the input terminal of the power source, a capacitor having a first electrode coupled to an output of the charging circuit, an electronic switching circuit, a discharge protection circuit, a control switch and a disconnecting device. An input of the electronic switching circuit is coupled to the first electrode of the capacitor. The control switch includes a first terminal which is coupled via the discharge protection circuit to the input terminal of the power source and is coupled to an output of the electronic switching circuit. The disconnecting device comprises a first terminal coupled to a second terminal of the control switch.