Multi-Voltage Battery Circuit for Overcurrent and Short-Circuit Protection
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Solution Overview
Problem
Multi-voltage battery devices in motor vehicles, particularly in hybrid electric or electric vehicles, are vulnerable to damage from excessive currents and electrical short circuits, which can lead to battery cell damage and malfunction.
Innovation Solution
A multi-voltage battery device with a controllable switch and protective resistor configuration, managed by a battery management assembly, that disconnects the battery cell group from the electrical system during excessive current conditions or short circuits to prevent overload and deep discharge, using a PTC resistor for overcurrent protection and a bidirectional DC voltage converter for charge balancing between battery cell groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first battery cell group remains electrically connected to the on-board electrical system during idle mode, then the vehicle can maintain relevant functions with minimal current consumption, but the battery cell group is exposed to excessive currents and electrical short circuits that can cause damage
Solution Approach 1:
A protective resistor is introduced as an intermediary element between the first battery cell group and the on-board electrical system. This resistor limits excessive discharge currents while allowing the battery to remain connected and supply minimal current during idle mode, thus protecting the battery from damage without completely isolating it
Solution Approach 2:
The battery management assembly is configured to detect excessive currents or short circuits in advance and switch the first switch into the open state before the battery can be damaged. This preliminary protective action prevents harmful effects while maintaining normal operation during acceptable conditions
2Reliability
If a protective resistor is connected in parallel with the first switch, then the battery cell group is protected from excessive currents, but power loss occurs due to the resistor
Solution Approach 1:
The system dynamically switches between two states: during normal operation, the first switch is closed providing low-resistance connection and minimal power loss; during excessive current conditions, the switch opens and the protective resistor becomes active to limit current. This dynamic switching optimizes both efficiency and protection
3Adaptability or versatility
If the second battery cell group is switchably connected in series with the first battery cell group, then the multi-voltage battery device can provide various rated voltages, but the system complexity increases
Solution Approach 1:
The battery device is segmented into two separate battery cell groups that can be independently controlled and switched. This segmentation allows flexible configuration where the second battery cell group can be connected in series with the first to provide higher voltages, or disconnected to provide lower voltages, enabling multi-voltage operation through modular switching
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
Effectively protects the battery device and on-board electrical system from damage by limiting discharge currents during overloads and short circuits, while minimizing power loss and preventing deep discharge, ensuring reliable operation and extended battery life.
Implementation Method 1
The protective resistor is configured to limit a discharge current of the first battery cell group in the event of an excessively high current or of an electrical short-circuit between the first electrical output terminal and the electrical ground terminal
Implementation Method 2
The protective resistor is designed as a PTC resistor
Implementation Method 3
a bidirectional DC voltage converter for charge balancing between battery cell groups
Data Source
AI summary
A motor vehicle multi-voltage battery device, includes: a first electrical output terminal and an electrical ground terminal providing a first rated voltage; a second electrical output terminal and the electrical ground terminal providing a second rated voltage; a first series circuit having a first battery cell group and a first controllable switch between the first electrical output terminal and electrical ground terminal; a protective resistor parallel to the first switch. The first switch configured to bridge the protective resistor in a closed state; a second battery cell group between the second electrical output terminal and the first electrical output terminal connected switchably in series with the first battery cell group; and a battery management assembly configured to switch the first switch into an open state to protect the first battery cell group.