Alternator Speed Detection Circuit Feedback Control
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Solution Overview
Problem
Existing speed detection circuits in turbine engines struggle to accurately detect shaft speed at lower speeds due to the shunt regulator preventing current flow when the voltage from the alternator does not exceed the voltage source, resulting in inaccurate speed indication.
Innovation Solution
A feedback circuit is introduced to override the pulse width modulation control, allowing additional current to flow through the shunt regulator switches when the voltage is below the voltage source, enabling the speed detection circuit to function accurately even at low speeds by providing a signal to the selection logic to allow current flow until the alternator reaches sufficient speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a shunt regulator controls current flow to the control circuit, then power efficiency is improved by preventing current flow when alternator voltage does not exceed voltage source, but speed detection accuracy deteriorates at lower speeds due to insufficient current
Solution Approach 1:
A feedback circuit is introduced as an intermediary between the speed detection circuit and the shunt regulator control. This feedback circuit monitors the alternator voltage and generates a feedback signal that overrides the normal shunt regulator control when voltage is below the voltage source threshold, ensuring sufficient current reaches the speed detection circuit even when the alternator is running at low speeds during startup.
Solution Approach 2:
The system implements a feedback mechanism where the feedback circuit continuously monitors the alternator output voltage and adjusts the shunt regulator control accordingly. When the alternator voltage is below the voltage source, the feedback signal triggers the shunt regulator to allow current flow, ensuring the speed detection circuit receives adequate current for accurate measurement. This feedback loop dynamically adjusts current flow based on real-time voltage conditions.
2Productivity
If the shunt regulator prevents current flow at low voltages, then power management is improved, but the speed detection circuit cannot function at lower speeds
Solution Approach 1:
The shunt regulator control is made dynamic through the feedback circuit, which continuously adjusts current flow based on alternator voltage conditions. Rather than a static on/off control, the system dynamically transitions between power-saving mode and detection-mode based on real-time voltage thresholds, ensuring both power efficiency and detection reliability are optimized at different operating conditions.
Solution Approach 2:
The system changes the operating parameter of current flow based on voltage conditions. When alternator voltage exceeds the voltage source, normal power-efficient operation occurs with standard shunt regulator control. When voltage drops below the threshold, the feedback circuit triggers a parameter change that allows increased current flow to ensure reliable speed detection, thus adapting system behavior to operating conditions.
3Loss of energy
If current flow is restricted by the shunt regulator control, then energy loss is reduced, but diagnostic capability deteriorates due to insufficient current for speed detection
Solution Approach 1:
The feedback circuit serves as an intermediary that protects diagnostic information integrity by monitoring voltage conditions and ensuring adequate current flow to the speed detection circuit when needed. This intermediary layer prevents information loss during critical low-voltage periods while maintaining energy efficiency during normal operation, thus resolving the conflict between energy conservation and diagnostic accuracy.
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
This solution ensures accurate shaft speed detection at lower speeds by ensuring a minimum current is provided to the speed detection circuit, enhancing diagnostic capabilities and control functions during engine startup.
Implementation Method 1
A permanent magnet alternator is driven by a turbine engine to supply three phases of power to a control circuit for the engine
Data Source
AI summary
A permanent magnet alternator is driven by a turbine engine to supply three phases of power to a control circuit for the engine. A shunt regulator delivers current to the control circuit, and a voltage supply is also included to deliver power for a period of time as the alternator is gaining speed at startup. A speed detection circuit detects the speed of the shaft for diagnostic purposes and a feedback circuit overrides a control for the supply of the current at lower speeds such that the speed detection circuit will be accurate even at lower speeds.