Laminated Bus Structure with Ground Layers for SiC Switching
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Solution Overview
Problem
Wide bandgap semiconductor devices, such as silicon carbide (SiC), face challenges with parasitic inductance and electromagnetic interference (EMI) during commutation processes in power converters, leading to over-voltage, over-current stresses, and electromagnetic interference, which existing solutions often address at the cost of safety tradeoffs.
Innovation Solution
The implementation of laminated bus structures with stacked conductive layers and additional conductive ground layers to minimize parasitic inductance and EMI, utilizing insulation layers like fiberglass and ceramics to reduce flux density and induced electromotive force, and incorporating multiple ground layers to act as electromagnetic shields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If laminated bus structures are used to reduce parasitic inductance, then switching capability is improved, but electromagnetic interference and electric field stress increase
Solution Approach 1:
Conductive ground layers are introduced as intermediary elements between power conductors to intercept and divert electromagnetic fields. These ground layers act as mediators that capture electric field stress and redirect it to ground, preventing it from affecting sensitive components while maintaining the low-inductance laminated structure for high-speed switching
Solution Approach 2:
The bus structure is segmented into multiple functional layers including power conductors, ground layers, and insulation layers. This segmentation allows each layer to perform its specific function: power layers handle current with minimal inductance, while interspersed ground layers provide EMI shielding and field stress management, enabling simultaneous optimization of switching speed and EMI reduction
2Object-affected harmful factors
If conductive ground layers are added as electromagnetic shields, then EMI is reduced, but device complexity increases
Solution Approach 1:
The conductive ground layers serve multiple functions simultaneously: they provide EMI shielding, manage electric field stress, establish reference potentials, and offer thermal pathways. This multi-functionality reduces the need for separate dedicated shielding structures, thereby limiting the increase in device complexity while achieving comprehensive EMI reduction
3Reliability
If insulation layers are used to manage electric field stress, then safety is improved, but parasitic inductance increases
Solution Approach 1:
Instead of relying solely on increased insulation thickness (one-dimensional approach) to manage electric field stress, the invention introduces ground layers in the vertical stacking dimension. This allows electric field management through vertical field interception by ground planes, enabling thinner insulation layers and smaller loop areas, thereby reducing parasitic inductance while maintaining safety
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 approach significantly reduces parasitic inductance and EMI, allowing for closer placement of sensitive components, improved power density, and reduced EMI, while maintaining safety by effectively managing electric field stress and parasitic inductance.
Implementation Method 1
incorporating multiple ground layers to act as electromagnetic shields
Implementation Method 2
reduce flux density and induced electromotive force
Implementation Method 3
utilizing insulation layers like fiberglass and ceramics to reduce flux density and induced electromotive force
Data Source
AI summary
Various embodiments of laminated planar bus structures that minimize electromagnetic interference (EMI) and parasitic inductance are described. In one embodiment, a laminated planar bus structure may include a plurality of stacked conductive layers and a plurality of stacked insulation layers. The plurality of stacked conductive layers may include positive and negative conductive layers, and conductive ground layers stacked as outer layers as to enclose vertically the positive and the negative conductive layers. In another embodiment, the laminated planar bus structure may include a middle ground layer stacked in between the positive and the negative conductive layers to provide additional reduction in electric field strength. A laminated planar bus structure that is integrated with other power electronics components is also presented.