Motor Vehicle Electrical System Voltage Stabilization
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Solution Overview
Problem
Modern motor vehicles equipped with start-stop functions face challenges in maintaining voltage stability during engine restarts, particularly due to high starter currents causing voltage drops in the vehicle electrical system, which can lead to inefficiencies and potential system failures.
Innovation Solution
A vehicle electrical system design featuring a starter and first energy storage device in one area, and a generator and second energy storage device in another, with a switching element allowing current flow only in one direction initially, and later interconnecting both areas via a DC/DC converter, enabling regulated charging and voltage stabilization. The second energy storage device can supply the starter directly, reducing the load on the DC/DC converter and enhancing voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the starter draws high current (up to 800 A) to restart the engine, then the engine can be restarted, but the voltage in the vehicle electrical system drops significantly (up to 6 V drop, reaching 6 V terminal voltage)
Solution Approach 1:
The patent segments the energy storage function into two separate energy storage devices: a first energy storage device connected to the starter and a second energy storage device connected to consumers. This segmentation allows each device to be optimized for its specific function, with the first device handling high-current starter operations and the second device maintaining stable voltage for consumers, thereby resolving the contradiction between starter power and voltage stability.
2Device complexity
If a single energy storage device is used for both starter and consumers, then the system structure is simple, but the voltage stability during starter operation deteriorates
Solution Approach 1:
The patent divides the electrical system into two separate circuits with dedicated energy storage devices: a starter circuit with a first energy storage device and a consumer circuit with a second energy storage device. This segmentation isolates voltage fluctuations from the starter operation, ensuring stable voltage supply to consumers while maintaining system manageability through clear functional separation.
Solution Approach 2:
The patent introduces a DC/DC converter as an intermediary component between the two energy storage devices. This converter acts as a mediator that regulates power flow and voltage levels, allowing the second energy storage device to support the first during starter operation while maintaining stable output voltage for consumers, thus resolving the voltage stability issue without excessive system complexity.
3Reliability
If the second energy storage device supplies the starter directly, then the voltage stability improves and the load on the DC/DC converter reduces, but the switching element complexity increases
Solution Approach 1:
The patent employs controllable switching elements that dynamically change their state based on operational requirements. The switching elements can configure the circuit in different modes: normally isolating the two energy storage devices, but temporarily connecting them during starter operation. This dynamic reconfiguration allows the second energy storage device to support the starter when needed while maintaining voltage stability, with the switching elements managing the complexity through automated control.
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 configuration improves voltage stability and restart capability by allowing the second energy storage device to supply the starter directly, reducing the need for high current handling by the DC/DC converter, thus enhancing the overall electrical system's reliability and efficiency during start-stop operations.
Implementation Method 1
a DC/DC converter is provided, via which the second energy store (9) can be connected to the on-board electrical system consumers (7, 8)
Implementation Method 2
a switching element (12, 13) is arranged, which has at least two switching states, wherein in a first switching state a current flow is only possible in the direction from the first area to the second area
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a motor vehicle electrical system (1) comprising a starter (2) and a first energy store (4), which are arranged in a first region of the motor vehicle electrical system (1), and a generator (6) and a second energy store (9), which are arranged in a second region of the motor vehicle electrical system (1), wherein, a switching element (12) is arranged between the first and the second region of the motor vehicle electrical system (1), wherein said switching element has at least two switching states, wherein, in a first switching state, a current can flow only from the first region toward the second region and, in a second switching state, the first and second region have a through-connection to one another, wherein the second energy store (9) is connected to the generator (6) via a DC/DC converter (10), wherein, via a second switching element (13), the starter (2) is connected directly to the second energy store (9). The invention also relates to a method for operating such a motor vehicle electrical system.