PCB Planar Transformer Layout for Low-Profile Isolated Gate Drivers
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Solution Overview
Problem
Existing multiple-output isolated power supplies for gate-driver circuits face challenges with high cost and high profile ferrite-core transformers, which are space-intensive and costly, particularly in automotive applications where space is restricted.
Innovation Solution
The use of planar transformers with flat, thin PCB windings and the omission of ferrite cores, allowing for a single transformer driver to generate multiple output voltages, with coil arrangements that include primary and secondary coils in a sandwiched configuration and electromagnetic shielding to manage fringing fields, reducing both space and material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If ferrite-core transformers are used for multiple-output isolated power supplies, then power conversion efficiency is maintained, but space requirements and cost increase significantly
Solution Approach 1:
The patent removes the ferrite core from the transformer structure, retaining only the planar coil windings on the PCB. This extraction eliminates the bulky ferrite material while maintaining the essential electromagnetic coupling function through air-core or PCB-trace-based magnetic fields, thereby reducing space requirements while preserving power conversion efficiency
Solution Approach 2:
The patent replaces the traditional mechanical ferrite core structure with an electromagnetic field-based solution using planar coils printed directly on PCB layers. This substitution eliminates the need for physical ferrite materials and their associated mounting structures, significantly reducing the transformer's footprint while maintaining functional performance
2Reliability
If ferrite-core transformers are used for multiple-output isolated power supplies, then magnetic coupling is achieved, but cost and profile height increase
Solution Approach 1:
The patent merges the transformer windings directly into the PCB structure using planar coil traces on different PCB layers. This integration eliminates the need for separate ferrite core components and their assembly, reducing both manufacturing cost and profile height while maintaining magnetic coupling through the PCB's inherent electromagnetic properties
Solution Approach 2:
The patent changes the physical parameters of the transformer by transitioning from a three-dimensional ferrite core structure to a two-dimensional planar coil configuration on PCB layers. This parameter change reduces the height profile and manufacturing complexity while maintaining the essential magnetic coupling function through optimized trace geometry and layer stacking
3Reliability
If multiple isolated power supplies are provided for semiconductor switches, then each gate driver circuit receives adequate power, but space in the power architecture increases significantly
Solution Approach 1:
The patent creates a single planar transformer structure that provides multiple isolated power outputs simultaneously, with each output serving a different gate driver circuit. This multi-functional design replaces what would traditionally require multiple separate transformers, thereby maintaining reliable power supply for all semiconductor switches while significantly reducing the total space occupied in the power architecture
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 solution reduces the cost and space requirements of power supplies in automotive applications by using lower-profile PCB windings and eliminating ferrite cores, enabling efficient power conversion while maintaining magnetic coupling and efficiency.
Implementation Method 1
Power conversion for the isolated power supplies may occur through use of transformers to transfer power from a power source to a load
Implementation Method 2
one or more ferrite materials, the one or more ferrite materials providing a shield for electromagnetic interference for the planar transformer
Data Source
AI summary
A planar transformer includes: a first primary coil in a first layer of a printed circuit board (PCB); a first secondary coil in one or more second layers in the PCB; and a second secondary coil in the one or more second layers.