Dynamic Deadtime Control for GaN Half Bridge Circuits
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Solution Overview
Problem
Half bridge circuits experience significant power losses and thermal stress due to reverse current and voltage during deadtime periods, particularly in high-power conversion applications using GaN transistors.
Innovation Solution
Incorporating a third quadrant state (TQS) detector that senses the reverse voltage across the transistors and generates signals to control the gate drivers, thereby shortening the deadtime periods and reducing power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the HS and LS gate drivers are synchronized to control both transistors to be OFF for a deadtime period to prevent shoot-through, then the reliability of the power supply is improved, but the power loss and thermal stress increase due to reverse current and voltage during deadtime
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed deadtime period to a dynamic deadtime that adapts to real-time operating conditions. The controller adjusts the deadtime duration based on feedback from the voltage detector, which monitors the actual voltage across the transistors. This allows the system to maintain sufficient deadtime for protection while minimizing unnecessary deadtime that causes power loss, thereby resolving the contradiction between reliability and energy efficiency.
Solution Approach 2:
The patent implements feedback by introducing a voltage detector that continuously monitors the voltage across the transistors during switching transitions and provides real-time information to the controller. This feedback mechanism enables the controller to dynamically adjust the deadtime period based on actual circuit conditions, ensuring adequate protection while minimizing power loss during deadtime, thus resolving the contradiction between reliability and energy efficiency.
2Reliability
If a fixed deadtime period is used to account for switching jitter and load characteristics, then the protection from shoot-through is improved, but the productivity decreases due to extended non-conducting periods
Solution Approach 1:
The patent applies dynamics by replacing the static fixed deadtime with a dynamic deadtime that adapts to real-time operating conditions. The controller adjusts the deadtime duration based on feedback from the voltage detector, which monitors the actual voltage across the transistors. This allows the system to maintain sufficient deadtime for protection while minimizing unnecessary deadtime that reduces productivity, thereby resolving the contradiction between reliability and power delivery efficiency.
Solution Approach 2:
The patent implements feedback by introducing a voltage detector that continuously monitors the voltage across the transistors during switching transitions and provides real-time information to the controller. This feedback mechanism enables the controller to dynamically adjust the deadtime period based on actual circuit conditions, ensuring adequate protection while minimizing power loss, thus resolving the contradiction between reliability and productivity.
3Reliability
If longer deadtime is used to ensure proper switching transitions, then the reliability is improved, but the loss of time increases reducing the switching frequency capability
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed deadtime period to a dynamic deadtime that adapts to real-time operating conditions. The controller adjusts the deadtime duration based on feedback from the voltage detector, which monitors the actual voltage across the transistors. This allows the system to maintain sufficient deadtime for proper switching transitions while minimizing unnecessary deadtime that limits switching frequency, thereby resolving the contradiction between reliability and time loss.
Solution Approach 2:
The patent implements feedback by introducing a voltage detector that continuously monitors the voltage across the transistors during switching transitions and provides real-time information to the controller. This feedback mechanism enables the controller to dynamically adjust the deadtime period based on actual circuit conditions, ensuring proper switching transitions while minimizing deadtime duration, thus resolving the contradiction between reliability and time loss.
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
The implementation of the TQS detector and controller significantly reduces the duration of deadtime periods, leading to lower energy dissipation and thermal stress in half bridge circuits, especially when using GaN transistors.
Implementation Method 1
a voltage detector, also referred to as a third quadrant state (TQS) detector, which detects voltage across the LS or HS transistor that experiences the reverse voltage during deadtime periods and generates signals responsive to the detected voltage
Data Source
AI summary
A half bridge comprising: a high side (HS) transistor; a low side (LS) transistor connected in series with the high side transistor at an output node of the half bridge; and a third quadrant state (TQS) detector connected in parallel with the HS or LS transistor and in series respectively with the LS and/or HS transistor, which TQS detector generates a signal responsive to a direction of a voltage drop across the transistor that is in parallel with the TQS detector.