Voltage Limiting Circuit for Controllable Switch Protection
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Solution Overview
Problem
Existing electrical systems with protecting circuits for components face high costs due to the need for controllable switches to support the full main DC voltage, especially when the switch is open, which can lead to damage from noise voltages and high currents.
Innovation Solution
Incorporating a voltage limiting circuit that restricts the switch voltage across the controllable switch to a portion of the main DC voltage, optionally using resistors and Zener diodes, and an auxiliary DC voltage source to stabilize the limiting voltage, allowing the switch to operate safely at lower voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controllable switch is designed to support the full main DC voltage when open, then the protecting circuit can effectively block noise voltage and prevent damaging current, but the cost of the controllable switch becomes very high
Solution Approach 1:
A voltage limiting circuit is introduced as an intermediary component between the main DC voltage source and the controllable switch. This circuit limits the voltage across the switch to a safe level (e.g., using a Zener diode or voltage divider), allowing the use of lower-voltage, lower-cost switches while maintaining protection capability through the combined action of the voltage limiter and switch
Solution Approach 2:
The voltage blocking function is segmented between two components: the voltage limiting circuit handles the high voltage portion by clamping or dividing the voltage, while the controllable switch handles only the remaining limited voltage portion. This segmentation allows each component to be optimized for its specific voltage requirement, reducing overall cost
2Reliability
If the controllable switch is opened to block noise voltage, then the electrical component is protected from damaging current, but the full main DC voltage appears across the switch requiring expensive high-voltage components
Solution Approach 1:
The voltage limiting circuit is configured to be active beforehand, continuously limiting the voltage across the controllable switch to a safe level even before noise voltage occurs. This prior cushioning prevents excessive voltage stress from ever reaching the switch, protecting it from damage without requiring the switch to be inherently high-voltage rated
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 solution reduces the voltage requirements for the controllable switch, enabling it to be designed for lower voltages, thereby reducing costs and preventing damage from noise voltages and high currents.
Implementation Method 1
the voltage limiting circuit comprises a first resistor connected across the supply lines and a second resistor connected across the controllable switch
Implementation Method 2
the first resistor is at least ten times greater than the second resistor
Implementation Method 3
the auxiliary DC voltage source comprises a closed loop for stabilizing the limiting voltage
Data Source
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AI summary
The electrical system (102) comprises two supply lines (L+, L-) between which the electrical component (C) is connected and a voltage limiting circuit (124) for limiting a switch voltage (Vmos) across a controllable switch (118) of the protecting circuit (116) placed on a selected one (L-) of the supply lines (L+, L-) to a portion of a maximum of a main DC voltage (Vbat) provided by a main DC voltage source connected between the supply lines (L+, L-) when the controllable switch (118) is open.