Gate Driver Voltage Staging for Turn-On Speed and Surge Noise
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Solution Overview
Problem
Existing techniques for driving semiconductor switching elements result in excessive turn-on speed and large surge voltage and radiation noise when the load current is zero or low, due to sudden increases in gate voltage.
Innovation Solution
A driver device that includes a gate drive circuit power supply capable of changing output voltage, a control unit to adjust the output voltage based on load current, and a delay circuit to supply a fixed voltage to the gate for a predetermined period before applying the output voltage, optimizing the turn-on speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the voltage applied to the gate is simply increased to reduce steady loss, then the steady loss is reduced, but the turn-on speed becomes excessive and surge voltage and radiation noise increase
Solution Approach 1:
The delay circuit performs preliminary action by holding the gate voltage at a fixed level for a predetermined period before allowing it to increase to the output voltage. This preliminary voltage holding action prevents excessive turn-on speed and the associated surge voltage and radiation noise, while still allowing the gate voltage to eventually reach the higher level needed for reduced steady loss.
Solution Approach 2:
The delay circuit provides beforehand cushioning by temporarily restraining the gate voltage increase, acting as a buffer that prevents the abrupt voltage rise that would cause excessive turn-on speed. This cushioning effect suppresses surge voltage and radiation noise before they can occur, while still permitting the full voltage benefit to be realized after the delay period.
2Speed
If the voltage applied to the gate sharply increases to improve turn-on speed, then the turn-on speed increases, but surge voltage and radiation noise become large
Solution Approach 1:
The delay circuit performs preliminary action by controlling the gate voltage to remain at a fixed level for a predetermined period before increasing to the output voltage. This preliminary control prevents the sharp voltage increase that would cause excessive turn-on speed and associated harmful effects, while still allowing the gate voltage to eventually reach the higher level for improved switching performance.
Solution Approach 2:
The system dynamically adjusts the gate voltage timing through the delay circuit, which adapts the voltage application based on the switching state. The delay circuit creates a dynamic control mechanism that prevents excessive turn-on speed by introducing a time delay, while still enabling the gate voltage to eventually reach the level needed for proper switching operation.
Data Source
AI summary
An object is to provide a technique capable of optimizing the turn-on speed. A driver device includes a gate drive circuit power supply capable of changing an output voltage; a power supply having a fixed voltage lower than the output voltage; a control unit that changes the output voltage of the gate drive circuit power supply on the basis of related information related to a load current of the semiconductor switching element; and a delay circuit that, when the gate drive signal is turned on, performs control to supply the fixed voltage to a gate of the semiconductor switching element for a predetermined period, and then performs control to supply the output voltage to the gate.