Parallel Switching Module Kelvin Wiring for Timing Synchronization
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Solution Overview
Problem
In switching modules using wide bandgap semiconductors, the deviation in switching timing between multiple switching elements connected in parallel exceeds allowable limits due to diverging currents caused by parasitic impedance and switching noise in Kelvin-connected wirings.
Innovation Solution
Increasing the resistance value of the Kelvin sense wiring or common Kelvin wiring to 1 mΩ or more for individual wirings and 3 mΩ or more for the common wiring reduces diverging currents and switching noise, acting as a damper to synchronize switching timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple switching elements are connected in parallel to increase current capacity, then the current capacity is improved, but the deviation in switching timing between elements exceeds allowable limits
Solution Approach 1:
A common Kelvin wiring is introduced as an intermediary to connect the source terminals of multiple switching elements. This common wiring serves as a mediator that equalizes the source potential among all parallel-connected switching elements, preventing potential differences that would cause timing deviations. The Kelvin wiring acts as a buffer that isolates the individual element potentials while maintaining synchronization.
Solution Approach 2:
The patent implements equipotentiality by connecting all source terminals of parallel-connected switching elements to a common Kelvin wiring. This ensures that all switching elements experience the same source potential, eliminating potential differences that would otherwise cause diverging currents and timing deviations. The common Kelvin wiring maintains equipotential conditions across all elements during switching operations.
2Measurement precision
If Kelvin-connected wirings are provided for each switching element, then measurement precision is improved, but parasitic impedance causes switching noise and timing deviation
Solution Approach 1:
Individual Kelvin wirings from multiple switching elements are merged into a single common Kelvin wiring. This consolidation reduces the total parasitic impedance by combining multiple low-impedance paths, thereby reducing switching noise while maintaining the measurement precision function. The merged common wiring provides a low-impedance return path that minimizes noise coupling.
Solution Approach 2:
The patent creates a common Kelvin wiring that copies and distributes the reference potential to all switching elements. Instead of each element having an independent Kelvin wiring that would accumulate parasitic impedance, the system uses a single copied reference path that serves all elements, reducing overall parasitic effects while maintaining measurement accuracy.
3Productivity
If wide bandgap semiconductors are used to increase operating speed, then productivity is improved, but crystal defects reduce yield and limit chip size expansion
Solution Approach 1:
Instead of using a single large switching element that would be limited by crystal defects, the patent segments the current capacity requirement into multiple smaller switching elements connected in parallel. This segmentation allows each element to be manufactured within acceptable yield limits while collectively achieving the required current capacity. The modular approach bypasses the chip size limitation imposed by crystal defects.
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 configuration effectively reduces deviations in switching timing between switching elements, ensuring they operate within allowable limits by minimizing diverging currents and switching noise.
Implementation Method 1
the Kelvin wiring has a Kelvin wiring predetermined portion at least a part of the Kelvin wiring, and the Kelvin wiring predetermined portion is at least one of the individual Kelvin wirings corresponding to at least one of the plurality of switching elements and has a resistance value of 1 mΩ or more, or the Kelvin wiring predetermined portion is at least a part of the common Kelvin wiring and has a resistance value of 3 mΩ or more
Data Source
AI summary
A switching module of the present disclosure includes: a plurality of switching elements each including a first electrode, a second electrode, and a control electrode; a first electrode wiring; a second electrode wiring; a control electrode wiring; and a Kelvin wiring including a common Kelvin wiring and individual Kelvin wirings electrically connecting the common Kelvin wiring to the second electrode of each of the plurality of switching elements. A Kelvin wiring predetermined portion is at least one of the individual Kelvin wirings corresponding to at least one of the plurality of switching elements and has a resistance value of 1 mΩ or more, or the Kelvin wiring predetermined portion is at least a part of the common Kelvin wiring and has a resistance value of 3 mΩ or more.