Variable-Permeability Inductor Core to Prevent Saturation
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Solution Overview
Problem
Inductor core saturation leads to rapid current increase and overheating in high-power applications, as existing technologies lack effective methods to dynamically control magnetic permeability to prevent saturation.
Innovation Solution
An inductor design featuring a core with a movable, controllably deformable metal part, such as a bi-metal strip, that adjusts its position or alignment relative to a fixed part via a heat source controlled by a sensor to vary the air gap and magnetic permeability, preventing core saturation by increasing the current required for saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inductor core is designed with fixed magnetic permeability, then the inductor achieves required inductance characteristics, but the core saturates at high current leading to rapid current increase and overheating
Solution Approach 1:
The patent applies the dynamics principle by making the inductor core's magnetic permeability dynamically adjustable through a bi-metallic strip mechanism. The strip deforms in response to temperature changes, which are caused by current flow, thereby automatically adjusting the air gap and magnetic permeability to prevent core saturation at high currents while maintaining simple overall structure
Solution Approach 2:
The patent applies parameter changes by utilizing the bi-metallic strip's temperature-dependent deformation to change the physical dimensions of the core structure. As temperature increases due to current flow, the bi-metallic strip deforms to increase the air gap, which changes the magnetic permeability parameter to prevent saturation
2Reliability
If gaps and supplementary magnetic materials are applied to inductor cores, then required inductor characteristics including saturation profile are achieved, but the device structure becomes more complex
Solution Approach 1:
The patent applies thermal expansion by utilizing the bi-metallic strip's differential thermal expansion properties. The two metals in the strip have different coefficients of thermal expansion, causing the strip to deform predictably with temperature changes, thereby automatically adjusting the air gap to control the saturation profile without adding complex mechanical structures
Solution Approach 2:
The patent applies self-service by designing a system where the bi-metallic strip automatically adjusts the air gap in response to temperature changes caused by current flow. This self-regulating mechanism controls the saturation profile without requiring external control systems or complex mechanical actuators
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 effectively prevents inductor core saturation by dynamically adjusting magnetic permeability, thereby avoiding overheating and ensuring stable operation in high-power applications.
Implementation Method 1
the controllably deformable metal part comprises a bi-metal strip deformable by heating of the bi-metal strip
Implementation Method 2
passing a variable electric current through the bi-metal strip thereby to heat the bi-metal strip according to the electrical resistance of the bi-metal strip
Implementation Method 3
a Hall Effect sensor for sensing a magnetic field due to a current when flowing in the coil
Implementation Method 4
the core comprises a first part 15, and a second part 20 comprising a movable metal portion
Implementation Method 5
a coil enclosing at least a part of a core
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
There is provided an inductor (5) having a coil (10) enclosing at least a part of a core (15, 20, 70, 90). A sensor (40) senses a current when flowing in the coil (10). The core comprises a first part (15), and a second part (20, 70, 90) comprising a movable metal part mounted relative to the first part (15) of the core such that the second movable metal part (20, 70, 90) is separated from the first part (15) of the core by an air gap (25, 30). A least a portion of the second part (20, 70, 90) is arranged to move relative to the first part (15), thereby to vary the magnetic permeability of the core (15, 20, 70, 90), according to an output of the sensor (40). In this way, if the output of the sensor (40) indicates an onset of saturation of the core (15, 20, 70, 90), the magnetic permeability of the core (15, 20, 70, 90) may be reduced by such movement. A method for varying the magnetic permeability of an inductor core (15, 20, 70, 90) is also provided.