Overvoltage Protection Circuit for Multivoltage Vehicle Systems
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Solution Overview
Problem
Multivoltage vehicle electrical systems face challenges in preventing crosstalk from high-voltage to low-voltage subsystems, leading to potential component destruction, due to the complexity and cost of existing galvanic separation methods, which also restrict the use of a shared engine ground connection.
Innovation Solution
An overvoltage protection circuit with a shared ground connection between the engine block and chassis, utilizing a comparator and passive/active measures to limit ground differential voltage, including Zener diodes and MOSFETs, to protect low-voltage components from overvoltage and prevent crosstalk without the need for separate ground straps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic separation is implemented to prevent crosstalk, then component safety is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a ground differential voltage monitoring system as an intermediary mechanism. A dedicated ground monitoring circuit continuously measures the voltage difference between the first ground connection (engine block) and second ground connection (chassis). When the ground differential voltage exceeds a predetermined threshold, the system triggers protective actions to prevent crosstalk damage, thereby maintaining component safety without requiring full galvanic separation
Solution Approach 2:
The monitoring system implements continuous feedback by measuring ground differential voltage and comparing it against threshold values. The system provides real-time feedback about ground connection status, enabling dynamic protective responses. This feedback mechanism allows the system to maintain reliability by detecting ground interruptions or excessive voltage differences and activating protection measures before crosstalk can damage components
2Reliability
If galvanic separation is implemented, then component safety is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs relatively simple and inexpensive monitoring components, including a dedicated ground monitoring circuit with voltage threshold comparators and basic protective elements. These cost-effective components provide sufficient protection against crosstalk without the high expenses associated with complex galvanic separation systems, making the solution economically viable for vehicle electrical systems
Solution Approach 2:
By introducing a monitoring circuit as an intermediary, the system achieves component safety through a low-cost detection and response mechanism rather than expensive galvanic separation. The monitoring circuit acts as a cost-effective mediator that prevents crosstalk damage without requiring expensive isolation components
3Reliability
If separate ground lines are provided, then crosstalk prevention is improved, but space requirements increase
Solution Approach 1:
The patent merges the ground connections by allowing both the first ground connection (engine block) and second ground connection (chassis) to coexist and be monitored together. Instead of requiring completely separate ground paths, the system combines the ground connections and uses voltage differential monitoring to detect and prevent crosstalk, thereby reducing space requirements while maintaining protection
4Reliability
If engine ground is insulated from engine block, then crosstalk prevention is improved, but robustness and cost are worsened
Solution Approach 1:
The monitoring circuit serves as an intermediary that enables the engine block to remain directly grounded (maintaining robustness) while still providing crosstalk prevention. The ground monitoring circuit detects voltage differences between the engine block ground and chassis ground, allowing direct grounding without insulation while maintaining protection through active monitoring and responsive 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
Effectively prevents overvoltage and crosstalk, ensuring component safety while maintaining a cost-effective and robust ground connection, allowing the engine block to serve as a shared ground for both voltage subsystems.
Implementation Method 1
the overvoltage protection circuit checks whether a ground differential voltage between the first ground connection and the second ground connection reaches a threshold value
Implementation Method 2
utilizing a comparator and passive/active measures to limit ground differential voltage, including Zener diodes and MOSFETs
Data Source
AI summary
An overvoltage protection circuit for a first subsystem of a multivoltage vehicle electrical system, in which the first subsystem having a first vehicle electrical system voltage, a second subsystem having a second vehicle electrical system voltage, and an electric machine for supplying the second subsystem. The first system voltage is less than the second system voltage. The overvoltage protection circuit includes a first ground connection for connecting a shared ground potential of the first subsystem, the second subsystem, and the electric machine, an additional second ground connection for connecting a reference ground potential, and a control connection for controlling the electric machine. The overvoltage protection circuit checks whether a ground differential voltage between the first and second ground connections reaches a threshold value, and for reducing the second vehicle electrical system voltage when the ground differential voltage between the first and second ground connections reaches the threshold value.