Filter Module for Turbojet Engine Speed Setpoint Overshoot
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Solution Overview
Problem
Turbojet engines face overshoot issues due to temporary exceedance of setpoints, leading to mechanical stress and increased mass, which existing methods to mitigate through fuel flow control adjustments degrade performance and require costly dispensers.
Innovation Solution
A method involving a filter module that filters the engine speed setpoint upstream of the corrector network, slowing down speed gradients near mechanical limits to prevent overshooting, comprising phases of non-protection, stabilization, and moderate acceleration to manage engine speed effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the speed control corrector network is adjusted to minimize overshoot, then overshoot is reduced, but the performance of the corrector is degraded
Solution Approach 1:
The invention extracts the filtering function from the corrector network and implements it as a separate module upstream of the corrector. This allows the corrector to maintain its optimal performance characteristics while the dedicated filter module handles overshoot prevention by limiting speed gradients in the setpoint signal.
Solution Approach 2:
The invention introduces an intermediary filter module between the raw setpoint and the corrector network. This intermediary processes the setpoint signal to remove harmful high-frequency components and limit speed gradients, thereby preventing overshoot without requiring modifications to the corrector itself.
2Object-affected harmful factors
If the speed control corrector network is adjusted to minimize overshoot, then overshoot is reduced, but fast and relatively expensive dispensers are required
Solution Approach 1:
The invention extracts the overshoot prevention function from the dispenser system and implements it upstream in the control signal path. The filter module limits speed gradients before they reach the corrector and dispenser, allowing the use of simpler, less expensive dispensers that do not require ultra-fast response capabilities.
Solution Approach 2:
The invention performs preliminary filtering of the setpoint signal to limit speed gradients before the signal reaches the dispenser. By pre-processing the command signal to remove harmful high-frequency components, the system prevents overshoot without requiring the dispenser to have exceptional speed and complexity.
3Object-affected harmful factors
If a safety margin is provided between maximum speed and mechanical strength limits, then overshoot is absorbed, but the mass of the turbojet engine increases
Solution Approach 1:
The invention replaces the mechanical solution (increasing engine mass and structural margins) with a control-theoretic solution (filtering the setpoint signal). By using a filter module to limit speed gradients and prevent overshoot, the system eliminates the need for oversized mechanical components and excessive safety margins, thereby reducing overall engine mass.
Data Source
Figure 1
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AI summary
This module (5) allows the filtering of a raw setpoint (N1_CMD_OP) intended for a corrector network (6) in an engine regulating system (20). It comprises: - a module (54) for detecting a filtering condition of said raw setpoint, and; - means for providing said corrector network with a filtered setpoint (N1_CMD_LIM) in place of said raw setpoint, when the filtering condition is detected.