Transformer Core Safe State Retention via Magnetic Saturation

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Solution Overview

Problem

Existing power supply systems lack reliable safe state retention and validation, especially in safety-critical applications, as they are difficult to test and maintain, and current solutions are either complex, expensive, or unable to prevent unsafe conditions.

Innovation Solution

A magnetically biased power supply with a reversibly saturated transformer core, where a permanent magnet saturates the core to prevent power transfer, and external intervention is required to de-saturate it, using bias windings or mechanical means, ensuring safe state retention and validation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fuse is used to remove power in response to a failure, then the system reaches a safe state, but the system becomes difficult to maintain and test

Engineering Contradiction:
Improvesafe state achievementVSAvoidmaintenance and testing difficulty
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The patent replaces the mechanical/electrical fuse-based power removal system with a magnetic field-based safe state mechanism. A permanent magnet provides a persistent magnetic field that saturates the transformer core, preventing power transfer without requiring physical fuse replacement or complex testing procedures. The magnetic field naturally persists without power and can be removed by physically removing the magnet, simplifying both safety achievement and system restoration.

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

2Reliability

If a vital relay is used to supply primary circuit power, then the system can reach a safe state by removing power from the relay, but the system becomes relatively large, expensive, and can only be tested by taking it off line

Engineering Contradiction:
Improvesafe state achievementVSAvoidsystem size and cost
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the essential function of the vital relay (power isolation for safety) and implements it through a simpler magnetic field mechanism. The permanent magnet directly saturates the transformer core to prevent power transfer, eliminating the need for complex relay assemblies, multiple contacts, and associated control circuitry. This reduces system size, cost, and enables inline testing while maintaining safe state capability.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If two processors are used to enable system operation, then system operation can be controlled, but it is impossible to prove that a latent failure is not blocking a processor from overwriting critical memory

Engineering Contradiction:
Improvesystem controlVSAvoidlatent failure detection
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent replaces the complex software-based processor control system with a simple magnetic field-based physical mechanism. The permanent magnet's magnetic field provides inherent, fail-safe control of power transfer through magnetic saturation of the transformer core. This physical mechanism cannot be blocked by software failures or memory corruption, and its state can be directly observed and verified through magnetic field measurement, eliminating latent failure detection problems.

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

4Ease of operation

If voltage is supplied to an output by shorting past or through processors, then power can be forced through, but this can cause an unsafe condition

Engineering Contradiction:
Improvepower forcing capabilityVSAvoidunsafe condition risk
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by using the permanent magnet to pre-saturate the transformer core in the safe state, preventing any power transfer before a fault can occur. The magnetic saturation acts as a preliminary barrier that blocks power flow regardless of subsequent attempts to force voltage through the system. This inherent magnetic blocking prevents unsafe conditions from developing, as the magnetic field must first be removed (by taking out the magnet) before power can flow.

Inventive Principle:
Principle #9Preliminary anti-action

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 enables reliable safe state retention and validation without incurring excessive costs, allowing for controlled restoration and reducing the risk of operator errors, while ensuring the power supply remains in a safe state until authorized intervention.

Implementation Method 1

a permanent magnet, which supplies, in a first mode of operation, a permanent magnetic field that saturates the transformer core for preventing transfer of power

Methodology Applied
Scientific EffectMagnetic saturation: Magnetic Saturation

Implementation Method 2

a primary winding, arranged adjacent the transformer core for supplying, while energized, a primary magnetic field for excitation of the transformer core

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP2698797B1Apparatus and method for safe state retention
Publication Date: 2019.08.28 ALSTOM TRANSPORT TECH SAS
  • EP2698797B1 patent drawingFigure 1
  • EP2698797B1 patent drawingFigure 2
  • EP2698797B1 patent drawingFigure 3~4

AI summary

A transformer core apparatus 11 includes a body of highly magnetically permeable material, a permanent magnet 18 arranged in a safe state position for saturating the body with a permanent magnetic field, and means 28, 30 for removing the permanent magnetic field from the body.