Ram Air Turbine Voltage Control to Prevent Stall and Doorbelling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional ram air turbine (RAT) systems experience overloading and stalling due to battery recharge current during emergency power transitions, leading to 'doorbelling' issues, which can be resolved by increasing the RAT's electrical rating and weight, but this is undesirable.
Innovation Solution
A system with a generator control unit (GCU) that regulates output AC voltage based on DC load current feedback, using a look-up table to linearly ramp voltage when the battery state-of-charge is low, preventing excessive load and stalling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the RAT generator is rated to be as small as possible to minimize weight, then weight is reduced, but the RAT becomes severely overloaded when battery recharge current combines with base load causing stalling
Solution Approach 1:
The patent implements dynamic control of the RAT generator output power based on real-time detection of turbine speed and load conditions. The control unit adjusts the generator output dynamically to prevent stalling while maintaining efficient operation, allowing the use of a smaller, lighter generator that can adapt to varying load conditions rather than being oversized for worst-case scenarios.
Solution Approach 2:
The system employs feedback control by continuously monitoring turbine speed, generator output, and load conditions. When the control unit detects conditions approaching stalling (through speed droop or load threshold detection), it automatically adjusts the generator output to maintain stable operation. This closed-loop feedback enables reliable operation with a minimally-sized generator.
2Reliability
If the RAT generator rating is increased to prevent stalling and doorbelling, then reliability is improved, but weight increases
Solution Approach 1:
Rather than using a statically oversized generator to handle peak loads, the patent employs dynamic power control that allows the smaller generator to meet varying demand. The control unit modulates output based on real-time conditions, enabling a lightweight generator to reliably handle both base loads and battery recharge currents without stalling or doorbelling.
Solution Approach 2:
The system changes operational parameters (generator output power, voltage, current) dynamically based on operating conditions. By adjusting these parameters in response to load changes and turbine speed variations, the smaller generator can maintain stable operation across a wider range of conditions without requiring increased physical size or rating.
3Reliability
If the AC contactor opens when total load exceeds threshold, then RAT stalling is prevented, but doorbelling occurs causing repeated disconnection and reconnection
Solution Approach 1:
The control unit performs preliminary detection of load conditions and turbine speed trends before the load threshold is actually exceeded. By anticipating approaching stalling conditions through proactive monitoring, the system can gradually adjust generator output or prepare for load management, preventing the abrupt contactor opening that causes doorbelling while maintaining continuous operation.
Solution Approach 2:
Instead of using a static threshold-based contactor control that causes abrupt disconnection, the patent implements dynamic control that continuously adjusts generator output based on real-time turbine speed and load conditions. This smooth, continuous adjustment prevents the sudden load changes that trigger doorbelling while maintaining stable operation throughout the charging process.
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
Prevents RAT stalling and doorbelling by managing the generator's output voltage, allowing smooth transitions and continuous battery charging without overloading the RAT.
Implementation Method 1
a generator configured to be turned by a RAT and to output an alternating current (AC) power
Implementation Method 2
a rectifying module configured to rectify the AC power into a direct current (DC) power
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
A ram air turbine (RAT) system can include a generator (101) configured to be turned by a RAT (103) and to output an alternating current (AC) power, a generator control unit (GCU) (105) configured to control an output of the generator, a rectifying module (107) configured to rectify the AC power into a direct current (DC) power, and a DC load (109) configured to receive the DC power from the rectifying module. The DC load can be operatively connected to the GCU to provide feedback from the DC load to the GCU. The GCU can be configured to control the output of the generator as a function of the feedback to prevent stalling of the RAT and/or doorbelling current and/or voltage in the system caused by disconnecting the generator from the DC load.