Generator Control Architecture With Independent Protection Logic
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Solution Overview
Problem
Conventional generator control architectures for aircraft electric systems lack adequate independence between control and protection functions, which can lead to erroneous control in case of protection function failures, necessitating external power quality monitoring that increases cost and weight.
Innovation Solution
An electric machine control system with a control unit and a protection unit, where the control unit receives feedbacks such as POR voltage, electric machine current, PMG, and input speed, and includes internal enable logic to enable or disable functions independently, with trip connections and BIT commands to prevent erroneous control, allowing the control unit to manage voltage and frequency regulation without reliance on the protection unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If control and protection functions are integrated in a single GCU, then device complexity is reduced, but independence between control and protection is compromised leading to potential erroneous control
Solution Approach 1:
The GCU is segmented into distinct control functions and protection functions that operate independently. The control unit handles voltage and frequency regulation, while the protection unit monitors for abnormal conditions and can trip the generator. This segmentation maintains functional independence within a single integrated device, resolving the contradiction between reduced complexity and maintained reliability.
2Reliability
If external power quality monitor is added to provide independent protection, then independence between control and protection is improved, but cost and weight increase
Solution Approach 1:
The protection unit is merged into the existing GCU architecture rather than using a separate external power quality monitor. This integration achieves the required independence between control and protection functions while avoiding the additional cost and weight of external monitoring equipment. The protection unit independently monitors generator parameters and can trip the generator without relying on external devices.
3Reliability
If multiple DSPs or microprocessors are used for independent control and protection, then reliability is improved, but device complexity increases
Solution Approach 1:
The GCU uses a single microprocessor that is functionally segmented into control and protection units. Each unit operates independently with its own logic and decision-making capabilities, achieving reliability through functional independence rather than through multiple physical processors. This approach maintains simplicity while ensuring that control failures do not compromise protection functions.
Data Source
AI summary
An electric machine control system includes a control unit, wherein the control unit includes inputs for a POR voltage feedback, an electric machine current feedback, a PMG feedback, and an input speed feedback. A protection unit includes inputs for: the POR voltage feedback, the electric machine current feedback, the PMG feedback, and the input speed feedback. At least one trip connection connects between the control unit and the protection unit. A method of generator control includes receiving an input speed feedback, a generator line contactor (GLC) auxiliary feedback, a generator control switch (GCS) feedback, and the weight on wheels feedback in a control unit. The method includes determining within the control unit if voltage regulation and/or frequency regulation should be enabled independent from a protection unit operatively connected to the control unit.