Surge Protected Power Supply Circuit for Aircraft
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Solution Overview
Problem
Aircraft electrical systems face damage from voltage surges caused by lightning strikes, as existing regulated voltage supply circuits fail to protect devices from transient voltage excursions effectively.
Innovation Solution
A controlled voltage supply circuit with an overvoltage protection mechanism, including a pass element, threshold switch, charge pump, and voltage references, which switches the pass element into a non-conducting state during voltage surges to prevent damage from large voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pass element is used to regulate voltage in aircraft electrical systems, then voltage regulation is achieved, but the pass element becomes vulnerable to damage from voltage surges caused by lightning strikes
Solution Approach 1:
A threshold switch is introduced as an intermediary component between the pass element and the voltage surge. The threshold switch remains non-conductive during normal operation but activates during voltage surges to divert excessive voltage away from the pass element, thereby protecting it from damage while maintaining voltage regulation functionality
Solution Approach 2:
The overvoltage protection circuit is configured to detect voltage surges before they can damage the pass element and preemptively activates the threshold switch to divert the surge. This preliminary protective action prevents the harmful voltage from reaching the pass element in the first place
2Reliability
If existing regulated voltage supply circuits are used, then voltage regulation is provided, but they fail to protect devices from transient voltage excursions during lightning strikes
Solution Approach 1:
The protection circuit incorporates dynamic components including a threshold switch that changes state based on voltage conditions, a charge pump that dynamically adjusts voltage levels, and capacitors that respond to transient changes. This dynamic configuration allows the circuit to adapt to both normal operation and surge conditions, providing both voltage regulation and surge protection
3Reliability
If the pass element is switched into non-conducting state during voltage surges, then protection from voltage magnitude surges is achieved, but voltage supply interruption occurs
Solution Approach 1:
The threshold switch is designed to activate only during extreme voltage surge conditions, allowing the circuit to skip over the harmful voltage peak and resume normal operation once the surge passes. This selective switching protects during surges while minimizing interruption duration under normal conditions
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 protects the pass element and connected devices from voltage surges by diverting excessive voltage away from the pass element, ensuring the regulated voltage supply remains stable and safe during lightning-induced voltage surges.
Implementation Method 1
a charge pump having an output electrically connected to the pass element control region and a first control region electrically connected to the second terminating region of the threshold switch input, the charge pump being capable of being directed at the first control region to provide a selected voltage at the charge pump output
Implementation Method 2
a voltage divider capable of maintaining at an output thereof a selected fraction of the voltage between a pair of terminating regions
Implementation Method 3
a first voltage reference capable of maintaining a substantially constant selected voltage between a pair of terminating regions for a range of electrical currents through that pair of terminating regions
Implementation Method 4
a coupling capacitor having one side thereof electrically connected to the oscillator output and the other side thereof electrically connected to the junction of the anode of a charge pump output diode and the cathode of a charge pump input diode
Data Source
Figure 1
AI summary
An overvoltage protection circuit for protecting a pass element (45-45"') in a controlled voltage supply circuit electrically connected between a circuit power supply interconnection terminal region (12) suited for electrical connection to a circuit power supply and an output terminal (14), the pass element being protected from voltage surges that may occur on the circuit power supply interconnection (12) with respect to a voltage reference interconnection (11). A voltage reference (18) is provided electrically connected in series with a voltage divider (16, 17) between the circuit power supply interconnection (12) and the voltage reference interconnection (11). A threshold switch (50) is electrically connected to a corresponding one of the voltage divider output and one of the voltage divider terminating regions, and has an output coupled to the pass element control region.