Multi-Voltage Battery Circuit for Short-Circuit Current Limiting
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Solution Overview
Problem
Multi-voltage battery devices in motor vehicles, particularly hybrid electric/electric vehicles, are at risk of damage from excessive currents and electrical short circuits, which can lead to battery cell damage and system failure, especially when one battery cell group remains connected during sleep mode.
Innovation Solution
A multi-voltage battery device with a first and second output current connection, a first series circuit of a battery cell group and a controllable switch, a protective resistor, and a battery management system that switches the switch to an open state during excessive currents or short circuits to limit discharge current through the resistor, protecting the battery cell group from overloading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a battery cell group remains electrically connected to the vehicle electrical system during sleep mode to maintain safety-related functions, then the vehicle can continue to perform relevant functions, but the battery cell group is at risk from excessive currents and electrical short circuits
Solution Approach 1:
A protective resistor is introduced as an intermediary element between the first battery cell group and the vehicle electrical system. This resistor limits excessive discharge currents while allowing the battery to remain connected for safety functions. The resistor acts as a mediator that permits necessary current flow for safety-related functions while blocking harmful excessive currents that could damage the battery cells.
2Reliability
If a protective resistor is electrically connected in series with the battery cell group to limit excessive discharge currents, then the battery is protected from overloading, but power loss increases due to the resistor
Solution Approach 1:
A controllable switch is introduced to dynamically adjust the circuit configuration based on operating conditions. During normal operation, the switch connects the protective resistor in series to limit excessive currents. When the vehicle is in sleep mode or under normal loading conditions, the switch can be opened to bypass the resistor, eliminating unnecessary power loss. This dynamic switching allows the system to adapt between protection mode and efficiency mode.
3Loss of energy
If a controllable switch is used to connect or disconnect the protective resistor, then power loss is minimized, but the device complexity increases
Solution Approach 1:
A battery management arrangement is implemented that monitors the operational state of the vehicle electrical system and automatically controls the controllable switch accordingly. The management system detects when the vehicle is in sleep mode versus active operation and switches the protective resistor in or out of the circuit accordingly. This feedback-based control automates the decision-making process, reducing the need for complex manual switching mechanisms while optimizing both protection and power efficiency.
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 effectively protects the battery cell group and the multi-voltage battery device from damage by limiting discharge current during excessive conditions and preventing deep discharge, ensuring reliable operation and minimizing power loss.
Implementation Method 1
a protective resistor (R) electrically connected between the two connections SA1, SA2 of the first switch ST1 and thus in parallel to the first switch ST1. The first switch ST1 is set up, in a closed switching state, to electrically short-circuit its two terminals SA1, SA2 with one another and thus to bridge the protective resistor (R).
Data Source
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AI summary
The invention relates to a multi-voltage battery device (MB) for a motor vehicle, comprising: - a first output current connection (AA1) and a ground connection (MA) for providing a first nominal voltage (U1); - a second output current connection (AA2) and the ground connection (MA) for providing a second nominal voltage (U2); - a first series circuit (SS1) of a first battery cell group (ZG1) and a first controllable switch (ST1) between the first output current connection (AA1) and the ground connection (MA); - a protective resistor (R) parallel to the first switch (ST1); - wherein the first switch (ST1) is designed to bridge the protective resistor (R) in a closed switch state; - a second battery cell group (ZG2) between the second output current connection (AA2) and the first output current connection (AA1), said second battery cell group being connected to the first battery cell group (ZG1) in series in a switchable manner; and - a battery management assembly (BM) which is designed to switch the first switch (ST1) to an open switch state in order to protect the first battery cell group (ZG1) in the event of a current which is too high or an electric short circuit between the first output current connection (AA1) and the ground connection (MA).