Gate-Driven Shoot-Through Protection Circuit for Series Transistors
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Solution Overview
Problem
Shoot-through or short circuit conditions in electrical circuits, particularly in space applications, occur when both upper and lower switches turn on simultaneously, leading to overheating and failure due to high energy particle hits, which conventional current sense circuits fail to prevent effectively, increasing complexity, mass, and cost.
Innovation Solution
A novel shoot-through protection circuit is introduced, incorporating an additional transistor connected in series with each pair of transistors to prevent simultaneous switching by pulling down or up the drive signal to the appropriate level, thereby preventing shoot-through conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional current sense circuits are used to detect shoot-through conditions, then shoot-through can be detected, but the circuit complexity, mass, and cost increase
Solution Approach 1:
The patent extracts the shoot-through protection function from complex current sense circuits and implements it using a simple additional transistor connected in series with the existing transistor pair. This third transistor is controlled by the gate driver circuit to directly block the shoot-through path without requiring current sensing components, thereby eliminating the need for complex detection circuits while maintaining protection capability
Solution Approach 2:
The third transistor acts as an intermediary protective element that is inserted into the circuit path. When a shoot-through condition is detected by the gate driver circuit, this intermediary transistor is activated to block the harmful current path, providing protection without requiring direct measurement or complex sensing of the main current flow
2Reliability
If additional protection circuits are added to prevent shoot-through, then reliability improves, but device complexity increases
Solution Approach 1:
The protection function is segmented into a dedicated third transistor that handles only the shoot-through protection task, while the original first and second transistors continue to perform their primary switching functions. This segmentation allows the protection mechanism to be added independently without complicating the main power conversion circuitry
Solution Approach 2:
The gate driver circuit is designed to perform multiple functions: it controls the switching of the main transistors for power conversion and simultaneously controls the third transistor for shoot-through protection. This multi-functionality eliminates the need for separate protection circuitry, reducing overall device complexity while maintaining comprehensive protection
Data Source
AI summary
A circuit comprising: first and second transistors connected in series; a third transistor (TT) comprising a source connected to a source of the second transistor (ST), a gate connected to a gate of ST, and a drain connected to a gate of the first transistor (FT); and a gate driver circuit connected to the gates of FT, ST and TT and configured to provide (i) a first drive signal to the gate of FT to cause FT to transition between an on state and an off state and (ii) a second drive signal to the gates of ST and TT to cause ST and TT to transition between on states and off states. The TT is configured to prevent a shoot-through condition in the circuit by pulling the first drive signal down to a level of the source of the ST when the ST is in the on state.