Toroidal Transformer Magnetic Shunt Current Limiting
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Solution Overview
Problem
Existing power supply systems face challenges in managing high output currents for low impedance loads, leading to potential damage and excessive heat generation, while also struggling to match impedance characteristics for efficient power transfer.
Innovation Solution
The use of a toroidal transformer with physically separated primary and secondary windings and strategically placed magnetic shunts to divert magnetic flux, combined with a control coil and variable resistance to dynamically control output current and impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistance is placed in line with the load to restrict output current, then the output current is limited to manageable levels, but waste heat is generated that requires cooling components increasing size and complexity
Solution Approach 1:
The patent replaces the mechanical/resistive current limiting approach with a magnetic field-based approach. A control coil generates a magnetic field that saturates the transformer core, creating an air gap effect that limits current without requiring resistive elements or active cooling components. This substitutes a magnetic control mechanism for the mechanical/resistive system.
Solution Approach 2:
The patent changes the magnetic parameters of the transformer core by introducing saturation through the control coil. By adjusting the DC current in the control coil, the magnetic flux density in the core is modified, creating a variable air gap effect that dynamically controls the output current without thermal losses.
2Reliability
If a resistance is placed in line with the load to restrict output current, then the output current is limited, but power transfer efficiency is degraded due to impedance mismatch
Solution Approach 1:
The patent replaces resistive current limiting with magnetic field control. The control coil generates a magnetic flux that saturates the core, creating an effective air gap that limits current while maintaining proper impedance matching. This eliminates the energy losses associated with resistive elements.
Solution Approach 2:
The patent introduces a control coil as an intermediary element that mediates between the input voltage and the output current. The control coil's magnetic field acts as a mediator to limit current while preserving the transformer's impedance transformation ratio, avoiding the efficiency losses of direct resistive limiting.
3Temperature
If air driven cooling is used to dissipate heat from resistive current limiting, then heat is dissipated, but components are damaged over time in dusty or chemically corrosive environments
Solution Approach 1:
The patent extracts and eliminates the need for cooling systems entirely. By using magnetic saturation to limit current, the harmful heat generation from resistive elements is removed from the system. Without heat generation, heat dissipation and associated cooling components are unnecessary, eliminating the reliability issues in harsh environments.
Solution Approach 2:
The patent converts the potentially harmful effect of magnetic flux into a beneficial current-limiting mechanism. By intentionally saturating the core with a control coil, the magnetic field becomes a useful tool for current control rather than a source of heat problems requiring cooling.
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 configuration effectively limits output current, reduces waste heat, and enhances power transfer efficiency by matching supply and load impedance, suitable for applications like electrical arc welding and contact electroplating.
Implementation Method 1
at least one magnetic shunt arranged within the geometry of the transformer to divert magnetic flux from the secondary winding
Implementation Method 2
a control coil and variable resistance to dynamically control output current and impedance matching
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
A power supply apparatus which includes a transformer having a primary winding and a secondary winding, whereby magnetic flux generated by a varying primary voltage applied to the primary winding induces a varying secondary voltage on the secondary winding, a torroidal transformer core over which said primary winding and secondary winding are applied, and at least one magnetic shunt arranged to provide a diversion path for magnetic flux generated by the primary winding which diverts magnetic flux from the secondary winding.