3-Level ANPC Power Module Layout for Low-Inductance WBG Switching
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Solution Overview
Problem
Existing power modules, particularly those based on traditional silicon devices, face challenges such as high power loop inductance, high gate loop inductance, and inadequate thermal management, which limit their performance and suitability for wide band gap (WBG) devices in high-power applications like electric vehicle propulsion.
Innovation Solution
The development of a power module with a three-level neutral point clamped (3 L NPC) topology using ultra-fast WBG semiconductors like gallium nitride (GaN), featuring a symmetrical layout, distributed terminals, decoupling capacitors, double-sided cooling, and mechanical robustness to minimize parasitic loop inductances and enhance thermal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional silicon devices are used in power modules, then manufacturing maturity and availability are improved, but power loop inductance and gate loop inductance increase, limiting performance for WBG applications
Solution Approach 1:
The patent transitions from traditional silicon devices to wide band gap (WBG) devices such as GaN and SiC, fundamentally changing the material parameter to achieve lower on-resistance and faster switching speeds. This parameter change enables the power module to operate at higher frequencies with reduced losses, directly addressing the high inductance limitations of silicon-based designs
Solution Approach 2:
The patent employs a three-level neutral point clamped (NPC) topology instead of conventional two-level designs, adding a voltage level dimension to the power conversion process. This topological change creates additional switching paths and allows for reduced voltage stress on individual devices, enabling better performance with WBG materials while managing the complexity of multi-level switching
2Object-affected harmful factors
If three-level NPC topology with WBG devices is implemented, then power loop inductance and gate loop inductance are reduced, but device complexity and layout requirements increase
Solution Approach 1:
The patent divides the power module into distinct functional segments: upper arm modules, lower arm modules, and neutral point modules. Each segment contains specific switches and associated gate drivers, allowing for modular assembly and simplified routing. This segmentation reduces the overall loop inductance by minimizing current path lengths within each module while managing the complexity through standardized interfaces
Solution Approach 2:
The patent integrates gate driver circuits directly into the power module structure, merging control and power functions into a unified design. The gate drivers are positioned adjacent to their corresponding switches with direct bonding, eliminating external gate drive traces and significantly reducing gate loop inductance. This merging approach consolidates multiple functions into a compact architecture, managing complexity through functional integration
3Productivity
If WBG devices are used in high-power applications, then switching speed and efficiency are improved, but heat generation during operation increases, requiring enhanced thermal management
Solution Approach 1:
The patent introduces copper heat spreaders and thermal interface materials as intermediary elements between the WBG devices and the cooling system. These intermediaries efficiently conduct heat away from the high-density device regions while distributing it across larger thermal mass, managing the temperature increases resulting from high-speed switching operations
Solution Approach 2:
The module design incorporates multi-functional elements such as copper layers that serve both as electrical current paths and as thermal conduction pathways. The same copper structures that provide low-inductance electrical connections also function as heat sinks and thermal management components, efficiently handling the heat generated by high-power WBG operations
Data Source
AI summary
A power module comprises: an upper arm structure that includes a first semiconductor switch, a second semiconductor switch and a fifth semiconductor switch; a lower arm structure that includes a third semiconductor switch, a fourth semiconductor switch and a sixth semiconductor switch; a first gate driving board, attached with the upper arm, wherein the first gate driving board includes gate drivers connected to gates of the first semiconductor switch, the second semiconductor switch, and the fifth semiconductor switch; a second gate driving board, attached with the lower arm, wherein the second gate driving board includes third gate drivers connected to gates of the third semiconductor switch, the fourth semiconductor switch, and the sixth semiconductor switch; etc.