PCB Planar Inductor Shielding to Contain Electric Field EMI
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Solution Overview
Problem
Wide-bandgap power devices in switch-mode power converters generate significant electromagnetic interference (EMI) emissions due to high switching frequencies, necessitating effective EMI suppression to comply with electromagnetic compatibility (EMC) regulations while maintaining power density and efficiency.
Innovation Solution
Integration of conductive shielding within the planar inductor structure using standard PCB manufacturing processes, comprising upper and lower conductive shield layers, inner and outer edge plates or rings, to contain the electric field and prevent parasitic electromagnetic couplings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conductive shielding is integrated within the planar inductor structure, then EMI emissions are reduced, but device complexity increases
Solution Approach 1:
The patent merges the shielding function with the inductor structure by integrating conductive shield layers directly into the PCB manufacturing process. The shield layers are combined with the winding structures and magnetic core to form a unified planar inductor assembly, eliminating the need for separate shielding components and reducing overall device complexity while maintaining EMI suppression effectiveness
Solution Approach 2:
The conductive shield layers serve multiple functions simultaneously: they provide EMI shielding, act as part of the magnetic circuit, and can be integrated with the winding structure. This multi-functionality allows a single component to address multiple concerns (EMI suppression, magnetic flux containment, and structural support) without increasing device complexity
2Power
If high switching frequency is used to achieve higher power density, then power density increases, but EMI emissions worsen
Solution Approach 1:
The patent converts the harmful high-frequency electromagnetic emissions into a manageable phenomenon by using the same high switching frequency to drive the inductor while the integrated shielding structure contains and directs the electromagnetic fields. The shield layers are designed to work with the high-frequency operation, converting what would be harmful radiated EMI into contained magnetic flux that can be efficiently utilized for power conversion
3Ease of manufacture
If integrated shielding is implemented using standard PCB manufacturing processes, then manufacturing ease improves, but shielding effectiveness may be reduced
Solution Approach 1:
The patent optimizes the parameters of the conductive shield layers (thickness, conductivity, geometric configuration, and positioning) to achieve effective EMI suppression using standard PCB manufacturing capabilities. By carefully selecting and adjusting these parameters, the design achieves shielding effectiveness comparable to more complex manufacturing processes while maintaining compatibility with standard PCB fabrication methods
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 integrated shielding effectively reduces EMI emissions by up to 25 dBV, improving EMC and reliability of power converters with minimal impact on cost and complexity, while maintaining efficiency at 0.14% lower than unshielded converters.
Implementation Method 1
a first conductive shield layer and a second conductive shield layer that are disposed between the PCB and the magnetic core
Implementation Method 2
a winding structure that includes a plurality of conductive windings arranged in layers around a magnetic core
Data Source
AI summary
An example planar inductor includes a winding structure including a plurality of conductive windings arranged in layers of a printed circuit board (PCB) around a core, where the plurality of conductive windings include at least a top winding and a bottom winding. The planar inductor includes a conductive shield encasing the winding structure. The conductive shield includes an upper conductive shield layer disposed over the winding structure in a first direction, a lower conductive shield layer disposed under the winding structure in a second direction opposite the first direction, an inner conductive shield disposed within and around the plurality of conductive windings, and an outer conductive shield disposed around and outside the plurality of conductive windings.