DC Voltage Converter Signal Ground Isolation Switch
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Solution Overview
Problem
Existing DC-DC converters face damage due to high operating currents flowing through electrical cable connections and shields, particularly when there is a high-impedance ground connection caused by corrosion or loss of a ground strap, which is not designed to handle such currents.
Innovation Solution
A device with a switch that isolates the signal ground line when the DC-DC converter is active and includes a measuring amplifier to detect voltage differences between the converter's ground and the vehicle ground, allowing for protection against excessive current loads by switching off the converter when a specified limit is reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the DC-DC converter uses a common ground connection for power output stages and control unit, then the device structure is simplified, but high operating currents can flow through cable connections causing damage
Solution Approach 1:
The invention segments the ground connection into two separate paths: a power ground connection for high-current power output stages and a signal ground connection for the control unit. This segmentation prevents high operating currents from flowing through the signal cable connections, thereby protecting them from damage while maintaining structural simplicity through dedicated separate pathways.
Solution Approach 2:
The invention introduces an intermediary isolation component (such as an optocoupler or transformer) between the power ground and signal ground paths. This intermediary allows the control unit to function with its own isolated ground reference, preventing direct current flow from power stages through signal cables while maintaining electrical isolation and safety.
2Ease of manufacture
If cable connections are used for ground connections, then installation is simplified, but corrosion or loss of ground straps causes high-impedance connections leading to current flow through unintended paths
Solution Approach 1:
By segmenting the ground system into separate power and signal grounds with dedicated low-impedance pathways, the invention ensures that corrosion or loss in one path does not affect the other. The power ground can maintain low impedance for high-current return while the signal ground provides a stable reference for the control unit, independently of each other.
Solution Approach 2:
The invention incorporates redundant ground paths and isolation mechanisms that provide backup pathways for current flow. If the primary ground connection becomes corroded or loose, the isolated ground system prevents complete failure by maintaining separate reference potentials, cushioning against the harmful effects of degraded connections.
3Object-affected harmful factors
If the signal ground line is isolated from the power ground, then protection from excessive currents is improved, but the device complexity increases due to additional isolation components
Solution Approach 1:
The invention uses standardized isolation components (optocouplers, transformers, or isolated DC-DC converters) as intermediaries between power and signal grounds. These are well-established, off-the-shelf components that provide reliable electrical isolation without requiring complex custom designs, thereby limiting current protection benefits while minimizing the increase in device complexity.
Solution Approach 2:
The isolated ground architecture serves multiple functions simultaneously: it protects signal lines from excessive currents, provides electromagnetic interference filtering, establishes independent reference potentials for noise-sensitive control circuits, and enables galvanic isolation for safety. This multi-functionality justifies the added complexity by delivering multiple benefits from a single architectural decision.
Data Source
Figure 1~3B
Figure 4~5
AI summary
The invention relates to an apparatus (1) for controlling and regulating a DC voltage converter (2), comprising one or more power output stages and a control unit (4) with a signal ground line (4.1) which have a common ground potential (M). A switch (5) for electrically disconnecting the signal ground line (4.1) is provided according to the invention, wherein the switch (5) is opened when the DC voltage converter (2) is active and the switch (5) is closed when the DC voltage converter (2) is inactive.