Electric Machine Winding Short-Circuit Detection via Equipotential Wire
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Solution Overview
Problem
Existing methods for detecting short-circuits in electric machine windings are inefficient, requiring numerous temperature sensors or complex signal processing, and struggle to distinguish fault signatures from normal operation, especially in machines with permanent magnets.
Innovation Solution
An electric machine design with an equipotential wire connecting electrical nodes and a current sensor to measure current imbalance between parallel paths, using a detection threshold twice the residual current to identify short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are implemented within the windings to detect heating, then detection sensitivity is improved, but device complexity and manufacturing cost increase due to requiring a large number of sensors
Solution Approach 1:
The invention extracts the detection function from multiple distributed temperature sensors and concentrates it into a single current sensor that measures current in the equipotential wire. This single sensor detects short-circuits by measuring current imbalances between parallel electrical paths, eliminating the need for numerous temperature sensors while maintaining detection sensitivity.
Solution Approach 2:
The current sensor in the equipotential wire serves multiple functions: it monitors current balance between parallel paths, detects short-circuits between turns, and provides early fault detection without requiring separate temperature sensing systems. This multi-functional approach reduces overall device complexity.
2Reliability
If signal processing techniques are used to analyze current harmonics, then fault identification capability is improved, but difficulty in distinguishing fault signatures from normal operation increases due to machine imperfections and unique signatures
Solution Approach 1:
The invention focuses detection on a specific local characteristic - the current balance between parallel electrical paths in the same phase. By measuring current in the equipotential wire that connects these paths, the system detects local imbalances caused by short-circuits between turns, avoiding the need to analyze complex global harmonic signatures that are difficult to distinguish from normal operation.
3Device complexity
If a single current sensor is used to measure current in the equipotential wire, then device complexity is reduced, but detection sensitivity may be compromised compared to multiple temperature sensors
Solution Approach 1:
The equipotential wire acts as an intermediary element that carries current representing the balance between parallel electrical paths. The current sensor measures current in this wire, which serves as a mediator that translates the electrical state of multiple windings into a single measurable signal. This intermediary approach maintains detection sensitivity while using only one sensor.
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
Provides a compact, sensitive, and reliable method to detect short-circuits with a single sensor, minimizing false positives and requiring minimal processing, thus ensuring rapid fault detection and machine safety.
Implementation Method 1
a current sensor configured to measure an electric current circulating in the equipotential wire, and in that the detecting means are configured to compare the electric current measured by the current sensor to a detection threshold
Implementation Method 2
the short circuit has the effect of reducing the flux in the path which has the fault (application of Lenz′ law). The induced voltage resulting from the product of the number of turns by the flux (Faraday's law) is therefore reduced in the path which has the fault
Implementation Method 3
This can cause a short-circuit which appears locally and generates local heating which can lead to the melting of the copper
Data Source
AI summary
An electric machine including at least one phase including two electrical paths in parallel, each electrical path of one and the same phase including a winding, the first electrical paths of all the phases being connected to one and the same first electrical node and the second electrical paths of all the phases being connected to one and the same second electrical node, the electric machine includes an equipotential wire electrically connecting the first and second electrical nodes and a current sensor configured to measure an electric current circulating in the equipotential wire.