Surge Recirculation Line for GaN Transistor Parasitic Inductance
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Solution Overview
Problem
In switching devices, particularly three-phase inverters or H bridge circuits, the use of snubber circuits to reduce surge voltage is hindered by parasitic inductance in the wiring, especially when high-speed transistors like GaN or SiC are used, leading to insufficient surge reduction due to inhibited charging/discharging currents.
Innovation Solution
The implementation of a surge recirculation device and line that creates a recirculation path for the surge voltage, allowing it to flow back to the power source node through a surge recirculation device, thereby reducing the impact of parasitic inductance and enhancing surge absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a snubber circuit is used to reduce surge voltage, then surge reduction effect is improved, but parasitic inductance in the leading wiring inhibits charging/discharging current, worsening the surge reduction effect
Solution Approach 1:
A surge recirculation device (diode) is introduced as an intermediary component to create a dedicated recirculation path for surge current. This mediator allows the surge current to flow through a low-inductance path back to the power source node, bypassing the parasitic inductance in the original leading wiring and enabling effective surge reduction even with high-speed transistors like GaN or SiC.
2Speed
If high-speed transistors (GaN or SiC) are used, then switching speed is improved, but the large charging/discharging current in short time cannot flow due to parasitic inductance, worsening surge reduction
Solution Approach 1:
The circuit path is segmented into two distinct paths: the original power supply path and a new surge recirculation path. By separating the surge current path from the normal power supply path, the recirculation path can be designed with minimal parasitic inductance, allowing high-speed transistors to operate at full speed while surge currents are safely recirculated through the dedicated low-inductance path.
3Adaptability or versatility
If there is a certain distance between power source terminals, then device layout flexibility is improved, but parasitic inductance in the leading wiring increases, worsening the charging/discharging current flow
Solution Approach 1:
The surge recirculation device acts as an intermediary that creates a local recirculation loop near the transistor. This allows the power source terminals to be positioned far apart for layout flexibility while the surge current is recirculated through the low-inductance path provided by the recirculation device and recirculation line, effectively isolating the surge current from the parasitic inductance in the long leading wiring.
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 the surge voltage by recirculating it through a path with lower parasitic inductance, improving the surge reduction effect, especially when using high-speed transistors like GaN or SiC, by allowing larger currents to flow quickly and efficiently.
Implementation Method 1
The surge recirculation device causes a current to flow in one direction
Data Source
AI summary
A high side transistor is coupled between a high potential side power source node and an intermediate node, and a recirculation diode is coupled between a low potential side power source node and the intermediate node, thereby forming a recirculation path when the high side transistor is OFF. A power source supply line couples the high potential side power source node with one end of the high side transistor. A surge recirculation device causes a current to flow in one direction, and a surge recirculation line couples the one end of the high side transistor to the high potential side power source node through the surge recirculation device, and causes a surge generated at the one end of the high side transistor to recirculate toward the high potential side power source node.