Vehicle Electrical System with Segmented Energy Storage and Step-Down Converter
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Solution Overview
Problem
Existing motor vehicle electrical systems with two energy storage devices are costly to implement and inflexible, as they often require bidirectional DC/DC converters and are not optimized for different battery technologies with varying charging voltages and internal resistances.
Innovation Solution
A motor vehicle electrical system with a starter, generator, and two energy storage devices of different technologies, connected in parallel with switching elements and a step-down converter, allowing for flexible operation and cost-effective implementation by using pure step-down converters, enabling different charging voltages and internal resistances, and providing fallback support in case of faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bidirectional DC/DC converters are used to connect two energy storage devices, then the system can achieve flexible operation and voltage matching, but the system cost and complexity increase significantly
Solution Approach 1:
The patent divides the electrical system into two independent partial vehicle electrical systems (first and second), each with its own energy storage device and consumer group. These segmented systems can operate independently or be coupled through a controllable electrical coupling device, reducing the need for complex bidirectional converters while maintaining flexibility.
Solution Approach 2:
The patent introduces a controllable electrical coupling device as an intermediary between the two partial vehicle electrical systems. This coupling device selectively connects the first and second energy storage units based on system requirements, enabling flexible operation without requiring direct bidirectional conversion between the energy storage devices.
2Adaptability or versatility
If bidirectional DC/DC converters are used to connect two energy storage devices, then voltage matching between different battery technologies is achieved, but the implementation cost increases
Solution Approach 1:
The controllable electrical coupling device serves as an intermediary that manages voltage compatibility between the first and second energy storage units. By selectively connecting these units based on voltage requirements and system state, the patent avoids the need for expensive bidirectional DC/DC converters while maintaining voltage compatibility across different battery technologies.
Solution Approach 2:
The electrical coupling device performs multiple functions including voltage matching, system isolation, and selective energy transfer between the two partial vehicle electrical systems. This multi-functionality replaces what would otherwise require separate bidirectional converters, reducing overall system cost.
3Adaptability or versatility
If two energy storage devices with different charging voltages are used, then optimization for different functions and battery technologies is achieved, but the system requires complex voltage management
Solution Approach 1:
The patent segments the vehicle electrical system into two independent partial systems, each with its own energy storage unit optimized for specific functions. The first energy storage unit (with first charging voltage) typically serves the starter, while the second energy storage unit (with second charging voltage) serves other consumers, allowing independent optimization without complex centralized voltage management.
Solution Approach 2:
The controllable electrical coupling device acts as an intermediary that manages voltage differences between the two energy storage units. By selectively connecting or isolating the partial electrical systems based on voltage compatibility requirements, the patent simplifies voltage management compared to directly paralleling different voltage systems.
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 system achieves a cost-effective and flexible electrical system that can optimize performance and space usage by allowing different battery technologies, ensuring reliable power supply and efficient charging, with the ability to handle voltage differences and support each other in case of voltage drops or faults.
Implementation Method 1
a step-down converter is arranged in parallel with the second switching element
Data Source
Figure 1~2
AI summary
The network (1) has an electrical energy storage unit (2) assigned to a starter (S). A shift element (8) is arranged between the energy storage unit and a generator (G). Another shift element (10) is arranged between another electrical energy storage unit (3) and the generator, where the electrical energy storage units comprise high charging voltage and low charging voltage respectively. A step-down converter (11) is arranged parallel to the shift elements of the energy storage unit at the low charging voltage. A diode (9) is arranged parallel to the former shift element. The electrical energy storage units are designed as a lead acid battery and a lithium-ion battery respectively. The shift elements are designed as relays or as power semiconductor switches. An independent claim is also included for a method for operating a motor car onboard network.