Programmable TVS Protection for Aircraft DC Bus Overvoltage

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Solution Overview

Problem

Aircraft DC power buses face challenges in controlling overvoltage events, which can lead to system failures due to increasing use of high power and voltage topologies in the aviation industry.

Innovation Solution

A protection system dynamically adjusts the voltage suppression level for a DC power bus using a series of transient voltage suppressors (TVS) and a controller that selectively shunts TVS devices to the low side of the electrical bus, enabling programmable overvoltage protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed voltage suppression level is used, then the protection system is simple, but it cannot adapt to different operating conditions and voltage levels

Engineering Contradiction:
Improvevoltage suppression level adaptabilityVSAvoidprotection system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The protection system is segmented into multiple independent TVS devices, each with different voltage suppression characteristics. This allows the system to selectively engage specific TVS devices based on the required suppression level, providing adaptability while maintaining modularity and manageable complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts the voltage suppression level by controlling the connection status of individual TVS devices through switches. The suppression level transitions from static to dynamic, adapting to different operating conditions such as generator load changes and motor shedding events, while the control logic manages the added complexity.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If multiple TVS devices with different voltage ratings are used, then programmable voltage suppression is enabled, but the device complexity increases

Engineering Contradiction:
ImproveprogrammabilityVSAvoidnumber of components
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Multiple TVS devices with different voltage ratings are integrated into a single protection system that serves multiple functions: protecting against different voltage levels, providing programmable suppression thresholds, and adapting to various operating conditions. The control unit coordinates these components to achieve universal protection across different scenarios.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system changes the operational parameters of the protection mechanism by selectively activating TVS devices with different voltage ratings. This allows programmable adjustment of the suppression threshold without requiring physical reconfiguration, enabling adaptability while managing component complexity through electronic control.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If TVS devices are selectively shunted, then precise voltage suppression control is achieved, but the control system complexity increases

Engineering Contradiction:
Improvevoltage suppression precisionVSAvoidcontrol circuit complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The control unit monitors the DC bus voltage and selectively activates TVS devices based on the detected voltage level. This feedback mechanism enables precise suppression control by engaging specific TVS devices only when their rated voltage matches the detected overvoltage condition, achieving precision while managing control complexity through intelligent decision-making.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The protection system partially self-regulates by using the voltage detection to automatically determine which TVS device should be activated. The control logic implements a decision algorithm that matches detected voltage levels with appropriate TVS ratings, reducing the need for complex external control and enabling self-service operation.

Inventive Principle:
Principle #25Self-service

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 system effectively suppresses transient voltages on the DC power bus with a dynamically adjustable threshold, preventing system failures and ensuring safe operation by allowing for customizable voltage protection levels.

Implementation Method 1

A series of transient voltage suppressors (TVS) across an electrical bus... The TVS devices may come in multiple voltage ratings and enable a high degree of programmability for the DC over voltage protection

Methodology Applied
Scientific EffectTransient voltage suppression: Avalanche Breakdown

Data Source

PatentEP4498549A1Programmable DC power bus over voltage protection
Publication Date: 2025.01.29 ROLLS ROYCE CORP
  • EP4498549A1 patent drawingFigure 1
  • EP4498549A1 patent drawingFigure 2A
  • EP4498549A1 patent drawingFigure 2B

AI summary

SUMMARY An example system includes a plurality of transient voltage suppressors (TVSs) that are connected in series across an electrical bus of an aircraft, the electrical bus having a high side and a low side; a plurality of switches, each switch of the plurality of switches configured to selectively shunt a corresponding TVS of the plurality of TVSs to the low side of the electrical bus; and a controller configured to: determine a desired voltage suppression level; and control operation of the plurality of switches such that the plurality of TVSs provides the desired voltage suppression level.