Ram Air Turbine Speed Control via Electrical Braking
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Solution Overview
Problem
Conventional fixed pitch ram air turbines experience response lag and are prone to over-speed conditions due to short duration transient load drops, leading to potential damage and disruption in power generation.
Innovation Solution
A system and method utilizing a power electronics controller to monitor and apply a braking load or torque to the ram air turbine when its speed exceeds a threshold, employing routing devices to manage power flow and mitigate over-speed conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional fixed pitch ram air turbines use actuating doors or throttle-like control mechanisms to limit air flow, then the amount of air flow entering or exiting the turbine can be controlled, but the system experiences inherent response lag and cannot account for short duration transient load drops
Solution Approach 1:
The patent replaces the mechanical actuating door or throttle-like control mechanism with an electrical/electronic braking system. The power electronics controller applies electrical braking torque to the turbine shaft, substituting mechanical air flow control with electrical torque control. This eliminates the response lag inherent in mechanical systems while maintaining the ability to control turbine speed during transient load drops.
Solution Approach 2:
The patent introduces a power electronics controller as an intermediary between the turbine and the load. This controller monitors turbine speed and applies braking torque through routing devices when transient load drops occur, acting as a mediator that responds instantaneously to speed changes without the mechanical lag of door mechanisms.
2Device complexity
If no speed control mechanism is used, then the system is simpler, but over-speed conditions occur which generate large unwanted forces and can disrupt or damage generators
Solution Approach 1:
The patent implements a feedback control system where the power electronics controller continuously monitors turbine speed and compares it to a reference value. When the turbine speed exceeds the reference during transient load drops, the controller applies braking torque to reduce speed. This closed-loop feedback provides reliable over-speed protection while maintaining relatively simple system architecture.
Solution Approach 2:
The turbine system includes an integrated braking mechanism that applies counter-torque to the turbine shaft during over-speed conditions. The system essentially self-regulates by using the generator and power electronics controller to apply braking torque, eliminating the need for separate mechanical governor mechanisms with counterweights.
3Reliability
If mechanical governing mechanisms with counterweights are used to control turbine speed, then speed control and power quality can be maintained, but the system complexity increases and response to transient load drops is delayed
Solution Approach 1:
The patent replaces the mechanical governing mechanism with counterweights with an electrical braking system controlled by power electronics. The mechanical system that used counterweights and linkages to adjust blade pitch is substituted with an electrical system that applies braking torque to the turbine shaft, reducing complexity while improving response time to transient load drops.
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 reduces the risk of over-speed and improves power quality by promptly controlling turbine speed during transient load drops, thereby minimizing damage and ensuring stable power generation.
Implementation Method 1
The rotational motion of the turbine is then converted into electrical and/or hydraulic power
Data Source
AI summary
A system of speed control for a ram air turbine of an aircraft includes a power electronics controller, at least one routing device in communication with the power electronics controller, at least one secondary load in serial communication with the at least one routing device and the power electronics controller, and a ram air turbine (RAT) in communication with the power electronics controller, wherein the power electronics controller is configured to apply the secondary load to the RAT through the at least one routing device in response to a transient speed increase of the RAT.