Switching Element Gate Drive Circuit for Low-Loss False Turn-On Suppression
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Solution Overview
Problem
Existing drive circuits for switching elements face challenges in reducing switching losses while preventing false turn-on events, particularly in wide bandgap semiconductor applications, where gate threshold voltages are low and noise-induced false turn-ons are common.
Innovation Solution
A drive circuit design incorporating a first and second power supply, a power supply switching unit, and an output switching unit, where the second power supply's output voltage is set to zero during the on-drive period to increase the drive voltage and reduce losses, and to a predetermined voltage during the off-drive period to apply a negative voltage and prevent false turn-ons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the drive voltage is increased to reduce switching losses, then the switching efficiency is improved, but the risk of false turn-on events increases due to noise interference
Solution Approach 1:
The drive circuit is segmented into multiple power supply units (first power supply, second power supply, third power supply) that operate independently during different periods. The second power supply provides high voltage during off-period to prevent false turn-on, while the first and third power supplies provide drive voltage during on-period, allowing each segment to optimize for its specific function without compromise
Solution Approach 2:
The second power supply applies a predetermined voltage (higher than the gate threshold voltage) to the gate electrode before the switching element is driven on, during the off-period. This preliminary action ensures that any noise during the subsequent on-period cannot cause false turn-on, as the gate already has sufficient voltage margin
2Device complexity
If a single power supply is used to simplify the circuit structure, then the device complexity is reduced, but the ability to simultaneously reduce switching losses and prevent false turn-on is compromised
Solution Approach 1:
The power supply function is segmented into multiple specialized units: the first power supply for drive voltage, the second power supply for false turn-on prevention, and the third power supply for voltage adjustment. This segmentation allows each unit to be optimized for its specific purpose, achieving superior performance compared to a single general-purpose power supply
Solution Approach 2:
The control circuit provides multi-functional control by managing multiple power supplies according to different timing periods. It can switch between providing high drive voltage for low switching loss and providing protective voltage for false turn-on prevention, making the system adaptable to different operational requirements
Data Source
AI summary
A drive circuit for a switching element includes: a first power supply; a second power supply; a power supply switching unit that switches the first and second power supplies for applying the drive voltage based on a drive command; and an output switching unit outputting an output voltage switching signal to the second power supply that the output voltage of the second power supply becomes zero in a part of a drive period of the switching element including at least a part of an on-drive period, and the output voltage becomes a predetermined voltage other than zero in a remaining part of the drive period including at least a part of an off-drive period.