IGBT Gate Driving Circuit With Dynamic Voltage Switching
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Solution Overview
Problem
There is a trade-off between increasing short circuit tolerance and reducing switching loss in semiconductor element driving circuits, as lowering the gate voltage on the IGBT side to enhance short circuit tolerance leads to higher switching losses.
Innovation Solution
A semiconductor element driving circuit that includes a transmission circuit for generating synchronization signals, a potential generation circuit for creating a step-up potential, and switch circuits to selectively output either the power supply potential or the generated potential to the gates of bipolar and unipolar transistor elements, optimizing switching loss and short circuit tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gate voltage on the IGBT side is lowered to increase short circuit tolerance, then short circuit tolerance is improved, but switching loss increases
Solution Approach 1:
The patent applies dynamics by making the gate voltage dynamically adjustable rather than fixed. The control circuit changes the gate voltage level based on operational conditions: using a first gate voltage during normal operation to minimize switching loss, and switching to a second gate voltage (lower than the first) during short circuit conditions to enhance short circuit tolerance. This dynamic adjustment resolves the contradiction between maintaining low switching loss and providing high short circuit tolerance.
Solution Approach 2:
The patent changes the voltage parameter of the IGBT gate based on operational state. By having the control circuit output different gate voltage levels (first gate voltage vs. second gate voltage) depending on whether a short circuit is detected, the system optimizes performance for each operating condition. This parameter change approach allows the system to achieve both low switching loss during normal operation and high short circuit tolerance when needed.
2Reliability
If the gate voltage on the IGBT side is constantly lowered, then short circuit tolerance is increased, but switching performance deteriorates
Solution Approach 1:
The control circuit dynamically adjusts the IGBT gate voltage based on operational conditions. During normal operation, the first gate voltage (higher level) is applied to maintain optimal switching performance and productivity. When a short circuit is detected, the control circuit switches to the second gate voltage (lower level) to enhance short circuit tolerance. This dynamic switching between voltage levels ensures both high productivity during normal operation and improved reliability during fault conditions.
Solution Approach 2:
The control circuit periodically monitors the operational state and adjusts the gate voltage accordingly. The system alternates between applying the first gate voltage during normal operation and the second gate voltage during short circuit conditions. This periodic monitoring and adjustment mechanism ensures that switching performance is maintained during normal operation while providing enhanced protection during fault conditions.
Data Source
AI summary
A semiconductor device includes a first switch and a first driver. The first switch selects and outputs one of a power supply potential and a generated potential as a first switch output potential based on a synchronization signal from a transmission circuit and a delayed signal delayed from the synchronization signal. The first driver charges a gate of a bipolar transistor element based on the synchronization signal of the transmission circuit and the first switch output potential.