Multiphase Stator Winding Layout for Short-Circuit Fault Current Mitigation
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Solution Overview
Problem
Electric machines, particularly surface permanent magnet machines, face significant challenges with large fault currents during insulation degradation, leading to rapid heating and potential fires, which limits their adoption in applications with high reliability and safety requirements.
Innovation Solution
A multiphase winding arrangement is introduced where turns of different conductor windings are not adjacent and do not share a common neutral point, allowing fault currents to be blocked or mitigated through control actions, such as adjusting voltage or using current source inverters, to prevent damage and maintain operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If surface permanent magnet machines are used to achieve high power density and high efficiency, then the machine performance is improved, but large fault currents occur during insulation degradation leading to rapid heating and potential fires
Solution Approach 1:
The machine is divided into multiple independent winding phases (first conductor winding and second conductor winding) with different neutral points. This segmentation ensures that a fault in one phase does not propagate to other phases, isolating the fault current to a limited path and reducing overall fault current magnitude.
Solution Approach 2:
The patent introduces an intermediary control system (voltage source inverter or current source inverter) that mediates between the power source and the windings. This intermediary can detect insulation degradation and implement control actions to block or mitigate fault currents before they cause damage.
2Device complexity
If conventional winding arrangements are used, then the machine structure is simple, but fault currents cannot be blocked or mitigated requiring the machine to cease operation
Solution Approach 1:
The winding arrangement is segmented into multiple independent phases with separate neutral points. This segmentation creates isolated current paths that prevent fault propagation, enabling fault tolerance without significantly increasing structural complexity.
Solution Approach 2:
The patent implements dynamic control capabilities where the inverter can adjust operating modes based on fault conditions. This allows the system to transition from normal operation to fault mitigation modes, maintaining reliability while preserving a relatively simple winding structure.
3Duration of action of moving object
If insulation degradation is allowed to progress, then the machine continues operating, but large fault currents cause rapid heating that can start a fire
Solution Approach 1:
The patent implements preliminary monitoring of insulation degradation and implements control actions before catastrophic failure occurs. The inverter detects early signs of insulation degradation and proactively mitigates fault currents, preventing rapid heating and fire hazards while maintaining operational continuity.
Solution Approach 2:
The system incorporates feedback mechanisms that continuously monitor winding conditions and provide real-time information to the control system. This feedback enables dynamic adjustment of control strategies to prevent temperature runaway while allowing continued operation during early-stage degradation.
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
The proposed winding configuration reduces fault currents from 5400% of nominal levels to 46% without control adjustments and further to 10.5% with voltage compensation, enabling the electric machine to operate near nominal conditions without disconnecting phases.
Implementation Method 1
the varying magnetic flux in the electric machine can induce large currents in the windings
Data Source
AI summary
An electrical machine including a stator. The stator includes slots to house conductors, the conductors arranged in the slots to provide a winding arrangement where: turns of a first conductor winding are not adjacent to each other, turns of a second conductor winding are not adjacent to each other, and the turns of the first conductor winding and the turns of the second conductor winding do not share a common neutral point and are not connected to each other in series or parallel.