Multi-Voltage Vehicle Electrical System Engine Start Voltage Dip
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multi-voltage vehicle electrical systems experience voltage dips during engine start due to high power demands, particularly affecting low-voltage branches and impacting other consumers.
Innovation Solution
A multi-voltage system with a controllable switching device that decouples the first low-voltage branch from the second during engine start, using a bidirectional DC/DC converter to manage energy flow between energy stores, allowing the high-voltage branch to support the low-voltage branch and maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the low-voltage vehicle electrical system branch is fed with energy from the second energy store via the DC/DC converter during engine start, then the voltage supply to low-voltage consumers is maintained, but the voltage dips significantly due to high power demand
Solution Approach 1:
The low-voltage vehicle electrical system is divided into two separate branches: a first low-voltage branch that is decoupled during engine start, and a second low-voltage branch that continues to supply power to consumers. This segmentation allows the high power demand of the starter motor to be isolated from the consumer supply, preventing voltage dips while maintaining reliable power delivery to low-voltage consumers.
Solution Approach 2:
The problematic first low-voltage branch is extracted and decoupled from the second low-voltage branch during engine start phase. By removing this branch from the active circuit, the high current draw during starting does not affect the voltage level in the second branch that supplies consumers, thus resolving the contradiction between maintaining voltage supply and avoiding voltage dips.
2Adaptability or versatility
If the controllable switching device is closed to connect both low-voltage branches, then energy can be shared between branches, but voltage dips affect the second branch during engine start
Solution Approach 1:
The controllable switching device dynamically changes its state based on the operating phase. During engine start, the switching device is opened to isolate the first branch and protect the second branch from voltage dips. During normal operation, the switching device is closed to allow energy sharing and flexible distribution between branches. This dynamic switching resolves the contradiction by adapting the system configuration to the specific operational requirements.
3Reliability
If the switching device is opened to decouple the first low-voltage branch during engine start, then voltage stability in the second branch is maintained, but the system complexity increases
Solution Approach 1:
The control device monitors the engine start phase and automatically controls the switching device to open or close at the appropriate times. This feedback-based control ensures that the switching device is opened precisely when the engine starter activates, providing voltage stability in the second branch without requiring complex manual intervention or overly sophisticated control systems.
4Power
If high-power consumers are connected to the high-voltage branch, then power-intensive functions can be integrated, but the hardware requirements and system complexity increase
Solution Approach 1:
The second low-voltage branch is designed to serve multiple functions: it supplies power to low-voltage consumers during normal operation, receives energy from the DC/DC converter during engine start, and can potentially serve as a high-voltage branch through the bidirectional DC/DC converter. This multi-functionality allows the system to support high-power consumers without requiring a completely separate high-voltage infrastructure, thus reducing overall system complexity while maintaining the capability to handle high-power loads.
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 effectively reduces voltage fluctuations in the low-voltage branch, enabling stable power supply to critical systems like entertainment devices and allowing integration of new power-intensive functions without significant hardware changes.
Implementation Method 1
a bidirectional DC/DC converter (10) which is set up and coupled to the second energy store (3) and to the controllable switching device (6) in such a way that the second energy store (3) can be fed with energy by the first energy store (4) via the controllable switching device (6) and via the DC/DC converter (10) or can be fed into the first low-voltage vehicle electrical system branch via the DC/DC converter (10)
Data Source
Figure 1
Figure 2
AI summary
The invention relates to an automotive multi-voltage vehicle electric system (1), comprising a generator (2), a first energy store (4), whose energy can be fed into a first low-voltage vehicle electric system branch with at least one first low-voltage consumer (7), and whose energy can be fed into a second low-voltage vehicle electric system branch with at least one second low-voltage consumer (8) by means of a controllable switching device (6), and a second energy store (3), whose energy can be fed into a high-voltage vehicle electric system branch, and whose energy can be fed into the second low-voltage vehicle electric system branch (8) by means of a DC/DC-converter (10). The controllable switching device (6) between the first switching configuration can be fed or is fed into the first low-voltage vehicle system branch by means of the DC/DC-converter (10) with energy of the second energy store (3), and a second switching configuration, in which the first low-voltage vehicle electric system can not be fed or is not fed by the DC/DC-converter (10) with energy of the second energy store (3), can be switched.