Electro-Pyrotechnic Fuse Triggering for HV Battery Short Circuits
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Solution Overview
Problem
Existing electrical fuses for high voltage batteries in motor vehicles face challenges in reliably interrupting connections during short circuits, especially at low temperatures, due to aging fuses and high current peaks, which can lead to contact welding and require larger wiring cross-sections, and existing solutions are complex and costly.
Innovation Solution
An electrical fuse with an electro-pyrotechnical detonator, a separating element, and a control circuit that includes a semiconductor switch, capacitor, and diode, where the inductive coupler induces a detonation current to trigger the detonator, allowing for reliable separation of the busbar even at low maximum currents, reducing material costs and installation space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional melt fuses are used to protect against short circuits, then the circuit can be interrupted, but the fuses require large cross-section wiring and have higher minimum triggering levels when new, which complicates the wiring design
Solution Approach 1:
The patent replaces the traditional thermal-magnetic breaker mechanism with a pyrotechnical detonator system. The detonator uses chemical energy to mechanically separate the busbar contacts, eliminating the need for large cross-section wiring and thermal-magnetic sensing mechanisms. This substitution enables reliable short circuit protection with simplified wiring design.
Solution Approach 2:
The invention changes the triggering parameter from thermal accumulation (traditional fuses) to electrical field detection via the field effect transistor. The FET detects voltage changes across the capacitor, enabling the system to respond to rapid current changes characteristic of short circuits without requiring large wiring cross-sections or thermal mass.
2Reliability
If electromechanical breakers are used to limit maximum current, then battery cells are protected from overload, but the breakers have complex control circuits and higher costs
Solution Approach 1:
The patent extracts the control circuit functionality from the protection device itself and places it in the vehicle's existing battery management system. The fuse only contains the passive capacitor and FET sensing elements, while the active control and decision-making reside in the external BMS, significantly simplifying the fuse's internal complexity.
Solution Approach 2:
The invention leverages the existing battery management system to perform multiple functions: normal overload protection, short circuit detection, and fuse triggering control. The FET-capacitor system serves as both a sensing element and a triggering mechanism, eliminating the need for separate control circuits.
3Reliability
If large cross-section wiring is used to accommodate aging fuse triggering levels, then the fuse can handle current peaks without false triggering, but material costs and installation space increase
Solution Approach 1:
The patent replaces thermal-magnetic sensing with an electrical field sensing mechanism using the FET and capacitor. This substitution allows the system to detect rapid voltage changes associated with short circuits without being sensitive to gradual thermal changes from normal current peaks, enabling the use of smaller wiring cross-sections.
Solution Approach 2:
The invention changes the detection parameter from thermal accumulation (which requires large wiring to prevent false triggering) to electrical field detection via the FET. The capacitor charges during normal operation and the FET remains off; during a short circuit, the rapid voltage change triggers the FET, enabling reliable detection with smaller wiring.
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 enables reliable interruption of electrical connections during short circuits at low temperatures, simplifies the control circuit, and reduces material costs and installation space, ensuring effective protection of high voltage batteries without complex current measurements.
Implementation Method 1
at least one inductive coupler located on the busbar or a high voltage line
Implementation Method 2
electro-pyrotechnical detonator, a separating element that can be moved by means of the electro-pyrotechnical detonator
Data Source
AI summary
An electrical fuse that includes an electro-pyrotechnic igniter, a separating element, which can be moved by the electro-pyrotechnic igniter, and a busbar with a separating section. A separating element is arranged so that it can move after the electro-pyrotechnic igniter is triggered to separate the busbar. At least one inductive coupler is arranged on the busbar or a high-voltage line. The electrical fuse further includes a control circuit for controlling an ignition current for triggering the electro-pyrotechnic igniter. The control circuit includes at least one semiconductor switch for switching the ignition current provided, at least one capacitor, connected to a control input of the semiconductor switch, and a diode coupled on one side to the at least one inductive coupler and on the other side to the capacitor and a control input of the semiconductor switch.