IGBT Gate Drive Slope Control for Transient Voltage Suppression
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Solution Overview
Problem
Conventional IGBT driving methods require additional passive power elements, such as RC or RCD snubber circuits, which increase losses and are inefficient in high voltage designs, especially during transient voltage events that can damage the IGBT.
Innovation Solution
A method to control the slope of the gate-emitter voltage using an IGBT driver IC, either by changing the inner resistance or extending the threshold voltage holding time, to reduce transient voltages across the IGBT during turn-off operations, thereby eliminating the need for snubber circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If snubber circuits are connected in parallel to prevent transient voltage, then the IGBT is protected from damage, but the number of passive power elements increases and additional losses are generated
Solution Approach 1:
The patent changes the gate-emitter voltage slope parameter during turn-off operation. By controlling the slope of the gate-emitter voltage to be reduced, the transient voltage across the IGBT is directly limited without requiring additional passive elements. This parameter change approach eliminates the need for snubber circuits while protecting the IGBT from voltage spikes.
2Reliability
If snubber circuits are connected in parallel to prevent transient voltage, then the IGBT is protected from damage, but the device complexity increases due to more passive elements
Solution Approach 1:
The patent extracts and eliminates the snubber circuit from the IGBT system by using an alternative protection method. By controlling the gate-emitter voltage slope through the driver circuit, the patent removes the need for external snubber components, thereby simplifying the overall device structure while maintaining IGBT protection.
3Object-affected harmful factors
If the gate-emitter voltage slope is reduced to limit transient voltage, then the transient voltage across IGBT is reduced, but the turn-off time increases
Solution Approach 1:
The patent employs dynamic control of the gate-emitter voltage slope rather than a fixed reduction. The driver circuit adjusts the voltage slope dynamically during the turn-off process, applying a reduced slope only when necessary to limit transient voltage, while maintaining faster switching characteristics during normal operation. This dynamic approach balances voltage protection with switching speed requirements.
Data Source
AI summary
A method for driving an IGBT, wherein a transient voltage applied across the IGBT is reduced by altering a rate of change of a gate-emitter voltage of the IGBT.