Electric Machine Winding Differential Protection
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Solution Overview
Problem
In electric machines, particularly those used in aircraft, a winding short circuit between turns can induce large electrical currents, leading to thermal destruction of tooth windings, which is a significant issue in multiphase rotating field machines with permanently excited rotors.
Innovation Solution
An assembly for an electric machine that includes a body with teeth and tooth windings, featuring a differential protection device with sensors to detect current differences between electrical conductors, allowing for early detection of short circuits and initiation of countermeasures to prevent damage, such as switching off the power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If tooth windings are used in electric machines, then the machine can generate magnetic fields for rotation, but winding short circuits can occur causing large currents and thermal destruction
Solution Approach 1:
The tooth winding is divided into multiple independent conductor bundles, each with its own differential protection. This segmentation allows localized fault detection and isolation without compromising the entire winding system, thereby maintaining power generation capability while improving reliability against short circuit damage.
Solution Approach 2:
Differential protection devices are installed in advance on each conductor bundle to detect short circuits before they cause thermal destruction. The protection devices continuously monitor current differences and can initiate countermeasures preemptively, preventing the harmful effects of winding short circuits before they escalate.
2Measurement precision
If differential protection devices with multiple sensors are installed on each conductor bundle, then turn short circuits can be reliably detected, but the device complexity increases
Solution Approach 1:
Instead of one complex protection system for the entire winding, the system is segmented into multiple simple differential protection devices, each monitoring a single conductor bundle with two current sensors. This segmentation maintains high measurement precision for short circuit detection while keeping individual protection device complexity low and manageable.
Solution Approach 2:
Each differential protection device is self-contained and independently functional, monitoring its own conductor bundle without requiring complex coordination with other protection devices. This self-service approach simplifies the overall system architecture while maintaining accurate short circuit detection capability across all conductor bundles.
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 solution effectively prevents thermal and electrical stresses by reliably detecting turn short circuits and initiating countermeasures, ensuring safe operation and preventing damage to the electric machine.
Implementation Method 1
The differential protection device includes current sensors configured to measure a current strength through the first electrical conductor at two or more points of the first electrical conductor
Implementation Method 2
signals from the current sensors for measuring the current strength through the first electrical conductor are provided to a comparator and/or signals from the current sensors for measuring the current strength through the second electrical conductor are provided to a comparator
Data Source
AI summary
An assembly for an electric machine includes: a body; a plurality of teeth fixed to the body; a plurality of tooth windings, wherein each tooth winding includes a first electrical conductor and a second electrical conductor that are wound around the same tooth at least at one winding section along a winding axis and thereby alternate in the direction of the winding axis; and a differential protection device with a plurality of sensors, (e.g., current sensors), wherein each sensor is configured to detect a voltage at, and/or the strength of a current through, the first conductor or the second conductor at least at two points of a tooth winding of the plurality of tooth windings.