GMR Sensor Transformer Saturation Prevention
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Solution Overview
Problem
Toroidal transformers with high flux density alloys tend to saturate abruptly, leading to high currents and inefficiencies, making it difficult to maintain stable voltage regulation due to rapid saturation and 'flux memory' effects, which can cause equipment overheating and outages.
Innovation Solution
The use of Giant Magneto-Resistive (GMR) sensors for direct, near-instantaneous measurement of magnetic flux density within the transformer core, allowing for real-time modulation of the magneto-motive force to prevent saturation, combined with a microprocessor-controlled PWM system to adjust the primary winding voltage and prevent deep saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If high flux density alloys are used in toroidal transformers, then transformer size and weight are reduced and efficiency is improved, but the core saturates abruptly leading to high currents and voltage regulation instability
Solution Approach 1:
The control system performs preliminary action by detecting approaching saturation conditions and modulating the primary voltage before actual saturation occurs. This preventive approach avoids the abrupt saturation and associated harmful effects while maintaining the benefits of high flux density operation.
Solution Approach 2:
The system employs feedback control by continuously monitoring transformer operation conditions and adjusting the primary voltage modulation in response to detected saturation tendencies. This closed-loop control maintains stable voltage regulation while preventing core saturation in high flux density transformers.
2Loss of energy
If the transformer is designed to operate near the saturation point for maximum efficiency, then energy losses are reduced, but the transformer becomes highly susceptible to saturation from voltage imbalances and harmonic distortion
Solution Approach 1:
The control system applies preliminary anti-action by detecting conditions that would lead to saturation (voltage imbalances, harmonics) and counteracting them through voltage modulation before saturation occurs. This allows the transformer to operate near the optimal flux density point while gaining tolerance to voltage disturbances.
Solution Approach 2:
The system introduces dynamics by continuously adjusting the primary voltage based on real-time detection of operating conditions. This dynamic control enables the transformer to adapt to voltage imbalances and harmonic distortion while maintaining efficient operation near the saturation point.
3Difficulty of detecting and measuring
If indirect saturation detection through excitation current monitoring is used, then saturation can be detected, but it is difficult to separate saturation indication from load-related overcurrent events
Solution Approach 1:
The patent introduces an intermediary approach by using a secondary winding to detect saturation conditions. This intermediary measurement method provides saturation detection that is independent of load current, allowing reliable distinction between saturation events and load-related overcurrent conditions.
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
This approach enables reliable, fast, and efficient control of magnetic flux density, reducing transformer saturation, minimizing current pulsations, and maintaining stable voltage regulation, thereby extending equipment life and improving power quality.
Implementation Method 1
The use of Giant Magneto-Resistive (GMR) sensors for direct, near-instantaneous measurement of magnetic flux density within the transformer core
Implementation Method 2
modulation of the magneto-motive force produced by the transformer primary winding
Data Source
AI summary
A system for preventing magnetic saturation in a transformer cores. A magnetic flux sensor is disposed within a bore in the core in a bore drilled or let into the material of a toroidal transformer core. The sensor transmits a sensor output that is continuously received by a microprocessor that is programed to process the sensor output and to also continuously compare in real time the sensor output with a stored selectable maximum flux sensor output value. Responsive to the comparison of real-time sensor output value to the stored maximum value, the microprocessor either allows, during each driving voltage half-cycle, the driving voltage to continue unabated while the sensor output remains below the selectable maximum value, or triggers a gate to modify the driving voltage for the remainder of the half-cycle when the selectable maximum value is reached.