Wireless Coil Power Supply for Medium-Voltage Switch Isolation
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Solution Overview
Problem
Conventional switch driving circuits for SiC semiconductor switching elements in medium voltage systems face issues with common mode current due to parasitic capacitance, leading to signal distortion and potential damage, while minimizing this capacitance results in larger transformer sizes that increase cost and reduce reliability.
Innovation Solution
A wireless power supply device using physically separated feed and collector coils, surrounded by insulating structures with epoxy molding and conductive paint, to concentrate electric field intensity and reduce parasitic capacitance, ensuring high insulation strength at 70 kV for 25 kV systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If parasitic capacitance is minimized by maximizing spacing between primary and secondary windings, then common mode current is reduced, but transformer size increases
Solution Approach 1:
A grounded shielding plate is introduced as an intermediary component between the primary and secondary windings. This shielding plate acts as a mediator that blocks parasitic capacitance coupling while maintaining a compact transformer structure, eliminating the need to increase spacing between windings to reduce common mode current
Solution Approach 2:
The parasitic capacitance path is extracted and isolated by introducing the shielding plate, which captures and grounds the parasitic capacitance effects, preventing them from affecting the secondary winding while maintaining compact dimensions
2Object-generated harmful factors
If isolation transformer size is increased to reduce parasitic capacitance, then common mode current is reduced, but system cost and complexity increase
Solution Approach 1:
The shielding function is merged with the existing transformer structure by placing the shielding plate within the transformer assembly, combining multiple functions (parasitic capacitance reduction, electromagnetic shielding, structural support) into a single integrated component rather than adding separate systems
3Object-generated harmful factors
If isolation transformer size is increased to reduce parasitic capacitance, then common mode current is reduced, but system reliability decreases
Solution Approach 1:
The shielding plate serves as a reliable intermediary that provides a controlled path for parasitic capacitance, grounding it away from sensitive circuits. This approach provides predictable and stable performance that improves system reliability compared to designs that rely on large spacing which may be sensitive to manufacturing tolerances and assembly variations
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 provides insulated power for switch driving with reduced size and weight, minimal common mode current, and increased output power up to 100 W, while maintaining 70 kV insulation strength.
Implementation Method 1
a feed coil connected to the high frequency conversion unit to generate AC power into an AC magnetic field; a collector coil spaced apart from the feed coil by a predetermined distance to generate AC power by an AC magnetic field radiated from the feed coil
Implementation Method 2
surrounded by insulating structures with epoxy molding and conductive paint, to concentrate electric field intensity and reduce parasitic capacitance
Data Source
AI summary
The present disclosure relates to a wireless power supply device for switch driving of a medium voltage system, and a method of manufacturing the same, and more specifically, the device may include a high frequency conversion unit for converting input power into AC power; a feed coil connected to the high frequency conversion unit to generate AC power into an AC magnetic field; a first insulating structure surrounding the feed coil; a collector coil spaced apart from the feed coil by a predetermined distance to generate AC power by an AC magnetic field radiated from the feed coil; a second insulating structure surrounding the collector coil; and a power conversion unit connected to the collector coil to rectify and convert AC power into DC power.