Power Switch Fault Detection Using Magnetic Coil Sensing

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Solution Overview

Problem

Existing methods for detecting electrical faults in power electronic devices, such as short circuits, are not quick enough to prevent device damage due to prolonged data processing times.

Innovation Solution

A device that uses a coil to measure the magnetic field generated by current flowing through power switches, with a processing circuit that detects faults based on voltage thresholds and current ratios, allowing for rapid identification of electrical faults during switching operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional current and voltage sensors are used to monitor power transistor parameters, then the device can detect electrical faults, but the data processing time is excessively long and prevents fast enough response

Engineering Contradiction:
Improvefault detection capabilityVSAvoiddata processing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces conventional current and voltage sensors with a magnetic field sensor (coil) that non-contactly detects current variations through magnetic field measurement. This substitution eliminates complex signal processing circuits and enables direct, rapid fault detection during the switching phase, reducing data processing time while maintaining reliability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field (intermediary) as a mediator between the current flowing through the device and the detection system. By measuring the magnetic field generated by the current instead of measuring current and voltage directly, the system achieves faster response times with simplified processing.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Speed

If non-contact magnetic field measurement is used, then response time is improved, but the device complexity increases due to additional sensor components

Engineering Contradiction:
Improvefault detection speedVSAvoidsensor system complexity
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The patent extracts only the essential function of current detection by using a simple coil to sense the magnetic field, eliminating the need for complex current sensors, voltage sensors, and associated signal processing circuits. This extraction of the core detection function reduces overall system complexity while improving speed.

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If multiple sensors and processing circuits are used to ensure accurate fault detection, then measurement precision is improved, but the device complexity and processing time increase

Engineering Contradiction:
Improvefault detection accuracyVSAvoidsensor and circuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces multiple sensors (current sensor, voltage sensor) and their associated processing circuits with a single magnetic field sensor. The coil directly measures the magnetic field proportional to the current, providing accurate fault detection with simplified hardware and reduced processing requirements.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Enables the quick detection of electrical faults, such as short circuits, allowing for timely interruption of the electrical supply to prevent device damage, with fault identification occurring in less than 2 microseconds.

Implementation Method 1

a coil (12) mounted on the support plate (16) and configured to measure a magnetic field created in said geometric plane by one or more electric currents flowing through said first and second connection terminals (6, 8)

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

The coil is adjacent to the first and second connection terminals and is configured to generate a voltage that is a function of the magnetic field created in said geometric plane by one or more electric currents flowing through the first and second connection terminals

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3748850B1Detection of an electrical defect in an electronic power device
Publication Date: 2025.01.22 ALSTOM HOLDINGS SA
  • EP3748850B1 patent drawingFigure 1
  • EP3748850B1 patent drawingFigure 2
  • EP3748850B1 patent drawingFigure 3(a)~3(b)

AI summary

This device (2), in particular a power electronic device, comprises: - a first power switch (S1) and a second power switch (S2) connected in series between first and second connection terminals (8, 6) of the device; - an electronic control circuit (10) configured to control the first and second power switches (S1, S2).This device includes a detection apparatus having at least one coil (12) associated with the first and second connection terminals and an electronic processing circuit (14) configured to identify the presence of an electrical fault in the device as a function of an electrical voltage measured by the coil (12), the electronic processing circuit (14) being mounted on a support plate (16) and the first and second connection terminals (8, 6) being arranged side by side, and preferably aligned, substantially in the same geometric plane (P1), the coil being mounted on the support plate (16) parallel to the first and second connection terminals to measure the magnetic field in said plane.