NS/PI Controller for Aircraft Arrestment Harmonic Suppression
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Solution Overview
Problem
Advanced arresting gear systems face challenges in controlling aircraft arrestment due to line imbalances and negative sequence harmonics, which destabilize current control topologies and reduce performance at high speeds.
Innovation Solution
The implementation of a negative sequence proportional integral (NS/PI) current control system with cross-coupled gains and delay state feedback, which transforms error signals into a negative sequence reference frame to minimize interference and suppress harmonics, allowing for high bandwidth and stability over a broad speed range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional current control topology is used, then system is simple to implement, but performance degrades at high speeds due to line imbalances and negative sequence harmonics
Solution Approach 1:
The patent introduces a negative sequence proportional integral (NS/PI) current control system as an intermediary control layer between the standard PI controller and the motor. This NS/PI controller specifically targets and suppresses negative sequence harmonics caused by line imbalances, allowing the system to maintain stable control across a broad speed range including high speeds where conventional controllers fail.
Solution Approach 2:
The patent implements delay state feedback that dynamically adjusts control parameters based on system state. By changing the feedback parameters in response to detected harmonics and line imbalances, the controller maintains optimal performance across varying speeds and operating conditions, resolving the contradiction between speed range and control stability.
2Reliability
If negative sequence proportional integral (NS/PI) current control system with cross-coupled gains and delay state feedback is implemented, then control stability and bandwidth are improved, but device complexity increases
Solution Approach 1:
The patent segments the control system into distinct functional blocks: a standard PI controller for basic control, an NS/PI current control system for harmonic suppression, and delay state feedback for stability enhancement. Each segment addresses a specific control challenge, allowing the complex overall function to be implemented through manageable, modular components that can be independently tuned and maintained.
3Reliability
If cross-coupled gains and delay state feedback are added to suppress harmonics, then performance robustness is improved, but manufacturing complexity increases
Solution Approach 1:
The patent implements delay state feedback that continuously monitors system performance and automatically adjusts cross-coupled gains to suppress negative sequence harmonics. This feedback mechanism ensures robust performance across varying operating conditions without requiring manual tuning or complex manufacturing processes, as the system self-adjusts to maintain optimal control.
Data Source
AI summary
The design of a novel digital controller for a motor driven aircraft arrestment system of the type used on aircraft carriers is described. The unique control and feedback design of the described controller has many advanced features, which provide many advantages over existing designs for controlling advanced arresting gear systems. Gain scheduling in engage/arrest controllers can be done based on estimated parameters such as speed, effective skew angle, and faults to allow optimized engage/arrest controllers, where the gain scheduling can be defined, discretely, for each “bin” as defined for a range of threshold values, or it can be defined, continuously, using interpolation and/or functions of speed and effective skew. Particularly, controller design gain values Kci and Kfi are picked to shape control loop transfer functions and dampen resonances in the aircraft arrestment system.