Electric Machine Partial-Phase Operation Using Back-EMF Position Sensing
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Solution Overview
Problem
Modern aeronautical gas turbine engines face challenges with the size and weight of electric machine assemblies, which affect efficiency and fuel consumption, and existing designs require shutting down entire winding sets in case of phase failure, leading to undesirable results.
Innovation Solution
An improved electric machine assembly and method that allows operation in partial phase mode by powering one set of windings to provide net zero current while maintaining one phase in a non-conducting condition, and using back EMF signals to determine rotor position without dedicated resolvers or encoders, enabling a more compact, redundant, and reliable system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional electric machine designs are used, then the system provides complete phase coverage, but the size and weight increase, affecting efficiency and fuel consumption
Solution Approach 1:
The patent divides the three-phase winding system into two independent sets (first set with phases A1, B1, C1 and second set with phases A2, B2, C2). Each set can operate independently or together, allowing the system to function with reduced weight by utilizing only two sets instead of three complete phase sets, thereby reducing overall machine size and weight while maintaining operational capability.
Solution Approach 2:
The patent changes the operational parameters by allowing the electric machine to switch between different operating modes: normal mode using all phases, and degraded mode using only one set of windings when a phase fails. This parameter change enables the system to operate efficiently with reduced weight characteristics while maintaining reliability through mode switching.
2Reliability
If entire winding sets are shut down in case of phase failure, then system safety is maintained, but operational reliability and redundancy decrease
Solution Approach 1:
The patent implements beforehand cushioning by designing the control system to detect phase failures and automatically switch to degraded operating modes before complete system failure occurs. The controller monitors the health of each phase and pre-prepared switching logic ensures continuous operation by transitioning to alternative winding configurations, thus cushioning against total operational failure.
Solution Approach 2:
The patent applies dynamics by enabling the electric machine to dynamically switch between different operational states: normal three-phase operation, degraded operation using one winding set, and complete shutdown only as last resort. This dynamic adaptability allows the system to maintain productivity and reliability by adjusting its operational mode based on real-time phase health status.
3Measurement precision
If dedicated resolvers or encoders are used for rotor position determination, then measurement precision is improved, but device complexity and weight increase
Solution Approach 1:
The patent implements self-service by enabling the winding sets to generate back electromotive force (back EMF) signals that the controller uses to determine rotor position autonomously. Instead of relying on external dedicated sensors like resolvers or encoders, the system uses its own operational characteristics (back EMF from the windings) to achieve precise rotor position measurement, thereby reducing device complexity and weight.
Solution Approach 2:
The patent replaces the mechanical sensor system (resolvers or encoders) with an electrical field-based solution using back EMF sensing. The controller measures the back EMF signals generated by the windings during operation and processes these electrical signals to determine rotor position, substituting mechanical measurement components with electrical field measurement and signal processing.
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 approach results in a lighter, more compact design with inherent redundancy, allowing efficient operation and enhanced reliability by eliminating the need for neutral or ground wires and enabling rotor position determination through back EMF signals.
Implementation Method 1
using back EMF signals to determine rotor position without dedicated resolvers or encoders
Data Source
AI summary
A method for operating an electric machine assembly is provided. The electric machine assembly includes an electric machine having a first set of windings and a second set of windings. The method includes: operating the electric machine in a partial phase mode, wherein operating the electric machine in the partial phase mode comprises: powering a first set of windings to provide a net zero current in the first set of windings while maintaining one phase of the first set of windings in a non-conducting condition; and powering a second set of windings to provide a net zero current in the second set of windings while maintaining one phase of the second set of windings in a non-conducting condition.