Synchronous Electrical Machine Phase Shift Harmonic Cancellation
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Solution Overview
Problem
Embedded synchronous electrical machines in gas turbine engines face challenges in fault detection and isolation, leading to difficulties in maintenance and replacement, and require large energy storage components due to uncancelled second harmonic currents during faults, especially in aerospace applications where electrolytic capacitors are not viable.
Innovation Solution
A synchronous electrical machine with multiple phases and power electronic converters that detect faults, isolate faulty phases, and adjust phase shifts between voltage and current to ensure the vector sum of second harmonic powers remains zero, reducing the need for large capacitors and facilitating efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the synchronous electrical machine is embedded in the gas turbine engine, then the complex mechanical transmission system is removed providing operational and efficiency benefits, but the machine becomes difficult to remove and replace if there is a fault
Solution Approach 1:
The electrical machine is divided into independent modular components (stator, rotor, end bells) that can be separately removed through access ports in the engine casing, allowing maintenance without complete engine disassembly while maintaining embedded operational benefits
2Reliability
If fault detection and isolation is implemented in the embedded synchronous electrical machine, then reliability is improved, but the device complexity increases
Solution Approach 1:
The power electronic converters perform multiple functions simultaneously: they enable bidirectional motor/generator operation, provide fault detection through current monitoring, isolate faulty phases, and control phase shifts for harmonic cancellation, reducing the need for separate dedicated components
Solution Approach 2:
Power electronic converters are introduced as intermediary devices between the electrical machine phases and the load, enabling fault isolation and harmonic control without requiring direct modification of the machine structure
3Reliability
If the synchronous electrical machine operates with faulty phases isolated, then the machine can continue operating, but large energy storage components are required due to uncancelled second harmonic currents
Solution Approach 1:
The control system dynamically adjusts the phase shift angle parameter of the remaining healthy phases based on the specific fault condition, optimizing the phase shift to maintain harmonic cancellation and minimize the required energy storage capacity
4Weight of moving object
If permanent magnet designs are employed in the synchronous electrical machine, then size and weight benefits are achieved, but the machine requires power electronic converters for motor operation
Solution Approach 1:
The power electronic converters serve multiple purposes: enabling motor operation of permanent magnet machines, providing fault detection and isolation, controlling phase shifts for harmonic cancellation, and managing bidirectional power flow, consolidating multiple functions into a single integrated system
Data Source
AI summary
A synchronous electrical machine having a plurality of phases, a detecting unit arranged to detect a fault in at least one of the phases of the synchronous electrical machine, an isolating unit arranged to isolate the at least one phase of the synchronous electrical machine with the fault, a phase shift unit arranged to produce a controlled phase shift between the voltage and the current within the remaining phases of the synchronous electrical machine to adjust the phase angle and magnitude of the second harmonic powers produced by the remaining phases of the synchronous electrical machine such that the vector sum of the second harmonic power vectors of the remaining phases of the synchronous electrical machine is zero.