Vehicle Power Network Segmentation for Fault Safety
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Solution Overview
Problem
In hybrid vehicles, existing systems shut down the entire electrical system when a fault occurs, posing safety risks and preventing continued operation of the vehicle.
Innovation Solution
A method that reduces the generator voltage to a safe level, allowing energy to flow from the high-voltage sub-network to the low-voltage sub-network via a DC-DC converter, ensuring safe operation and minimizing risks to people by disconnecting the high-voltage battery and selectively powering essential loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the high-voltage battery is disconnected from the on-board sub-network in the event of a fault, then the safety of persons is improved, but the other on-board sub-network can no longer be supplied with electrical energy and the entire motor vehicle is switched off
Solution Approach 1:
The electrical system is divided into two independent on-board sub-networks: a high-voltage sub-network and a low-voltage sub-network. Each sub-network can be independently controlled and protected. When a fault occurs in the high-voltage sub-network, only that sub-network is switched off while the low-voltage sub-network remains operational, allowing critical vehicle functions to continue.
Solution Approach 2:
A DC converter acts as an intermediary between the high-voltage and low-voltage on-board sub-networks. This converter enables selective disconnection of the high-voltage battery while maintaining power supply to the low-voltage sub-network through the converter, thus isolating the fault while preserving vehicle operation.
2Object-affected harmful factors
If the entire vehicle electrical system is switched off in the event of a fault, then the safety of persons is improved, but the ability to operate the motor vehicle is lost
Solution Approach 1:
The electrical system is segmented into independent high-voltage and low-voltage sub-networks with separate control mechanisms. This allows selective shutdown of only the faulty high-voltage sub-network while maintaining operation of the low-voltage sub-network, preserving essential vehicle functions during fault conditions.
Solution Approach 2:
Different protection strategies are applied to different parts of the electrical system. The high-voltage sub-network receives full disconnection protection while the low-voltage sub-network maintains operational continuity. This localized quality approach ensures safety where needed while preserving productivity where possible.
3Object-affected harmful factors
If the generator voltage is reduced to a safe level, then the safety of persons is improved, but the electrical energy available to the on-board sub-networks is reduced
Solution Approach 1:
The generator voltage is made dynamically adjustable based on operating conditions and fault states. During normal operation, the generator provides full voltage for optimal energy availability. When a fault is detected, the voltage is dynamically reduced to a safe level, and the DC converter compensates to maintain stable power supply to the low-voltage sub-network.
Solution Approach 2:
The voltage parameter of the generator is changed from a fixed high value to a variable parameter that can be adjusted between high-voltage mode (normal operation) and low-voltage mode (fault condition). This parameter change allows the system to adapt to different operational requirements while maintaining safety constraints.
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
Enables the motor vehicle to operate safely during faults by maintaining electrical supply to critical systems, reducing the risk of breakdowns in critical situations and ensuring continued operation without hazardous voltages.
Implementation Method 1
The on-board sub-networks are coupled to one another via a DC converter so that the voltage of one on-board sub-network is converted and can supply another on-board sub-network
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method for operating an on-board power network (1) of a motor vehicle (2), wherein said on-board power network (1) has at least two on-board sub-networks (4, 5) of differing electrical voltages and there is a coupling (6) between said on-board sub-networks (4, 5) allowing an electrical energy flow, and wherein the one on-board sub-network (4) is connected to a generator (26) and/or at least one electrical consumer (86) and the other on-board network (5) is connected to at least one electrical consumer (86). According to the invention, in case of error the voltage supplied from the generator (26) is lowered to a value that is not dangerous to people, wherein an energy flow still takes place from said on-board sub-network (4) having said generator (26) to said other on-board sub-network (5) having said consumer (86).