Fault Tolerant Electrical Machine Phase Short-Circuit Control
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Solution Overview
Problem
Conventional fault-tolerant electrical machines in gas turbine engines experience mechanical and electrical ripple torque or power due to short-circuits, which can lead to overheating and are difficult to manage with existing energy storage devices, adding size and weight to the system.
Innovation Solution
A fault-tolerant electrical machine with multiple independent phases, each equipped with a converter, detects short-circuits and intentionally creates a short-circuit in another phase to cancel out time-dependent power terms, ensuring the vector sum of second harmonic power vectors remains zero, thereby preventing ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a short-circuit fault occurs in a phase, then overheating is prevented, but mechanical and electrical ripple torque or power occur
Solution Approach 1:
The patent applies the principle of converting harm into benefit by intentionally creating a controlled short-circuit fault in a healthy phase to cancel out the harmful second harmonic power vectors generated by the detected faulty phase. The controller calculates the second harmonic power vectors from each phase and deliberately induces a short-circuit in another phase such that the vector sum of all second harmonic power vectors becomes zero, thereby eliminating mechanical and electrical ripple torque while maintaining overheating prevention.
2Object-generated harmful factors
If energy storage devices such as capacitors and inductors are used to smooth ripple, then mechanical and electrical ripple torque is reduced, but size and weight of the system increase
Solution Approach 1:
Instead of using energy storage devices to mitigate ripple effects, the patent employs a control strategy that converts the harmful second harmonic power vectors into beneficial cancellations. By intentionally creating controlled short-circuit faults in healthy phases, the system generates opposing second harmonic power vectors that sum to zero, eliminating ripple torque without requiring additional capacitors, inductors, or other energy storage components that would increase system weight.
3Temperature
If conventional short-circuit protection is applied to a faulty phase, then overheating is prevented, but the vector sum of second harmonic power vectors becomes non-zero causing ripple
Solution Approach 1:
The patent transforms the conventional approach by not merely protecting the faulty phase but actively using controlled short-circuit faults in healthy phases to generate beneficial second harmonic power vectors. The controller continuously monitors and calculates second harmonic power vectors from each phase and deliberately induces short-circuits in healthy phases to ensure the vector sum equals zero, thereby eliminating ripple torque and improving operational efficiency while maintaining thermal protection.
Data Source
Figure 1~3
AI summary
A fault tolerant electrical machine (40) for use in a gas turbine engine comprising: a plurality of phases (50A-D); a detector (52A, 52B, 52C, 52D) arranged to detect a short-circuit fault in at least one of the phases (50A-D); and a controller (52A, 52B, 52C, 52D) arranged to intentionally cause a short-circuit fault in at least one other of the phases (50A-D) such that the vector sum of the second harmonic power vectors of the remaining phases is zero, in order to reduce or eliminate mechanical torque ripple.