PCB-Coupled Gate Driver Power Transformer for Low Parasitic Capacitance
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Solution Overview
Problem
Existing isolated power supply designs for medium voltage SiC power devices face challenges in achieving high voltage isolation with low parasitic capacitance, leading to increased device volume and manufacturing difficulties.
Innovation Solution
A coupled transformer design using two magnetic cores and coupling coils, embedded in a printed circuit board (PCB), which enhances magnetic coupling between primary and secondary windings while maintaining high voltage insulation and reducing parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional transformer with magnetic core is used, then high voltage isolation is achieved, but parasitic capacitance increases
Solution Approach 1:
The transformer core is divided into two separate C-cores instead of using a single conventional core. This segmentation reduces the parasitic capacitance between primary and secondary windings while maintaining the required voltage isolation, directly resolving the contradiction between isolation capability and parasitic capacitance reduction.
Solution Approach 2:
The patent applies different structural characteristics to different parts of the transformer. The C-cores are positioned and configured to provide high voltage isolation in critical areas while minimizing capacitance coupling in other areas. The asymmetric arrangement of windings around the C-cores optimizes the local electromagnetic properties to reduce parasitic effects.
2Reliability
If copper wires are wound across toroidal core with insulation tape, then voltage isolation is achieved, but parasitic capacitance increases and manufacturing reliability decreases
Solution Approach 1:
The patent removes the insulating tape layer from the design by using PCB-based windings instead of traditional wire winding with insulation tape. This extraction of the problematic insulation layer eliminates the source of high parasitic capacitance while the PCB structure provides sufficient voltage isolation through its inherent dielectric properties.
Solution Approach 2:
The patent replaces the mechanical wire-winding system with a PCB-based winding system. The PCB windings are created through standard PCB fabrication processes (copper traces on insulated substrate) rather than manual wire winding, which eliminates the need for insulation tape and reduces parasitic capacitance while improving manufacturing consistency and reliability.
3Object-affected harmful factors
If two C-cores are used instead of toroidal core, then parasitic capacitance is reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent combines the two C-cores with the PCB windings into an integrated assembly where the C-cores are mounted directly on the PCB and the copper traces are routed around them. This merging of components simplifies the overall structure compared to separate wire-wound cores, reduces assembly steps, and makes the device easier to manufacture while maintaining the low parasitic capacitance benefit.
4Reliability
If entire power supply is enclosed in potting material, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The PCB substrate serves multiple functions: it provides the winding structure, electrical insulation, mechanical support, and structural housing. By making the PCB multi-functional, the patent eliminates the need for separate potting material while maintaining reliability, thus simplifying the manufacturing process without compromising isolation performance.
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 achieves low parasitic capacitance and high voltage isolation, reducing the impact of fast switching transients and simplifying manufacturing, making it suitable for medium voltage converter systems.
Implementation Method 1
a coupling coil, which improves the magnetic coupling between the primary and the secondary
Implementation Method 2
a primary magnetic core and a secondary magnetic core, each wound with a corresponding winding
Data Source
AI summary
The present disclosure provides a power transformer for medium voltage semiconductor devices. In one aspect, the power transformer includes a primary winding and a secondary winding, a primary magnetic core wound by the primary winding, a secondary magnetic core wound by the secondary winding, and a coupling coil wound about the primary and secondary magnetic cores.