Capacitance Discharge Limiter for DC Voltage Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing limiter circuits are ineffective in rapidly addressing sudden voltage excursions from DC to about 9 KHz, which can damage receivers and power limiters due to insufficient reaction time, especially when a capacitor is present between the source and the limiter.
Innovation Solution
A capacitance discharge limiter with a DC transition protection circuit that filters input signals to detect DC and low-frequency voltage, generates a transient control voltage to activate a discharge circuit, and rapidly discharges the capacitor to circuit ground, thereby protecting the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a capacitor is placed between the source and the power limiter, then the circuit can maintain signal integrity and filter high-frequency noise, but the capacitor accumulates charge that creates dangerous voltage excursions during rapid transitions, damaging the receiver and limiter
Solution Approach 1:
A detection circuit is introduced as an intermediary between the capacitor and the power limiter. This detection circuit monitors the voltage across the capacitor and triggers the power limiter when excessive charge accumulation is detected, preventing damage while allowing the capacitor to maintain signal integrity during normal operation
Solution Approach 2:
The system implements feedback by having the detection circuit continuously monitor the capacitor's voltage state and provide control signals to the power limiter. When the capacitor charge exceeds safe thresholds, the feedback mechanism activates the power limiter to discharge the capacitor, thereby preventing harmful voltage excursions while preserving the capacitor's beneficial filtering function
2Reliability
If prior art limiters are used, then they can limit high-frequency voltage excursions above 1 MHz, but they cannot react fast enough to limit sudden transitory events in the DC to 1 MHz frequency range
Solution Approach 1:
The protection function is segmented into two independent circuits: a detection circuit specialized for DC to low-frequency monitoring, and a power limiter circuit for high-frequency limiting. This segmentation allows each circuit to be optimized for its specific frequency range, with the detection circuit providing fast response to low-frequency transients while the power limiter handles high-frequency excursions
Solution Approach 2:
The system dynamically adapts its response based on the frequency and magnitude of the input signal. The detection circuit activates the power limiter only when necessary, allowing the system to maintain normal operation during benign conditions while providing rapid protection when DC to low-frequency voltage excursions occur
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 solution effectively suppresses both the magnitude and duration of transient voltages from capacitors, providing rapid protection against sudden voltage excursions and ensuring the safe operation of receivers.
Implementation Method 1
there is effectively a capacitor 106 between the source 102 and the power limiter 100... the capacitor 106 is suddenly charged to a DC potential... the accumulated charge across the capacitor 106 discharges
Implementation Method 2
the DC transition protection circuit generates a transient control voltage Vctrl for the power limiter that is higher than the normal control voltage Vref... The transient control voltage forces the power limiter to a low impedance mode, which discharges the capacitor to circuit ground in a very short period of time
Data Source
AI summary
A capacitance discharge limiter in which a DC transition protection circuit is provided in a circuit that includes a discharge circuit (which may be a power limiter) between a source and a receiver, with a capacitor situated between the source and the discharge circuit. The DC transition protection circuit is coupled to a reference voltage and to the control voltage input of the discharge circuit, and also between the capacitor and the discharge circuit at a node. The DC transition protection circuit detects the existence of an excess DC or low frequency (typically less than about 1 MHz) voltage potential at the node caused by charge on the capacitor, and regulates the control voltage so as to enable the discharge circuit to discharge the capacitor to protect the receiver.