Dual-Battery On-Board Network Switch Assembly for Vehicle Power Redundancy
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Solution Overview
Problem
The 48-Volt on-board electrical network in motor vehicles faces challenges in maintaining stable voltage for starting the engine at low temperatures and ensuring operational safety, particularly with lithium-ion batteries not delivering sufficient current and requiring a 12-Volt lead-acid battery for starters, while also needing system redundancy for safety systems like Shift-by-Wire and Park-by-Wire.
Innovation Solution
Implementing a dual-battery system with two main batteries of essentially equal capacity, connected via a switch assembly that allows for fault management and system redundancy, ensuring continuous energy supply and reducing overheating risks, with a 3-way or 2-way changeover switch and isolating switch configurations to maintain reliable operation across different modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a 48-Volt lithium-ion battery is used in the on-board electrical network, then the power consumption for comfort systems and dynamic consumers is improved, but the battery does not deliver sufficient electrical current at low temperatures to start the engine
Solution Approach 1:
The on-board electrical network is segmented into two separate voltage circuits (12V and 48V) with dedicated batteries for each function. The 48V lithium-ion battery handles high-power comfort systems and dynamic consumers, while the 12V lead-acid battery is dedicated to engine starting, allowing each battery to be optimized for its specific function without compromise
2Reliability
If a second battery is added to stabilize the on-board supply voltage for engine starting, then the starting reliability is improved, but the device complexity and installation space increase
Solution Approach 1:
The 12V lead-acid battery serves multiple functions: it provides engine starting power, stabilizes the on-board supply voltage during starting operations, and can support low-power consumers when the ignition is switched off. This multi-functionality reduces the need for additional dedicated components
3Reliability
If system redundancy is implemented for safety systems like Shift-by-Wire and Park-by-Wire, then the operational safety is improved, but the device complexity increases
Solution Approach 1:
System redundancy is achieved by introducing a temporal dimension through the switch assembly, which enables dynamic reconfiguration of the electrical network topology. The switch assembly can isolate faulty batteries or circuits and reroute power flow, providing redundancy without duplicating all safety system components
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 enhances the robustness and operational safety of the on-board network by ensuring continuous energy supply, reducing installation space, and eliminating the need for a smaller backup battery, while maintaining equal total capacity and simplifying the system design.
Implementation Method 1
a uni- or bidirectional DC/DC converter supplies the 12-Volt on-board network from the 48-Volt onboard network
Implementation Method 2
the first voltage circuit having a battery and the second voltage circuit having at least one main battery
Data Source
AI summary
The invention relates to a method for operating an on-board electrical network (4) of a motor vehicle (2), having a first voltage circuit (I) and a second voltage circuit (II), the first voltage circuit (I) having a first operating voltage which is higher than a second operating voltage in the second voltage circuit (II), wherein the first voltage circuit (I) is connected to the second voltage circuit (II), the first voltage circuit (I) having a battery (10) and the second voltage circuit (II) having at least one main battery (12a) and a second main battery (12b), wherein the first main battery (12a) and the second main battery (12b) have essentially the same capacity, and wherein components of the motor vehicle (2) are supplied with electrical operating energy from the first main battery (12a) and/or the second main battery (12b) by means of a switch assembly (14).