Power Switch Gate Drive Circuit for Voltage Overshoot Reduction
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Solution Overview
Problem
Power modules with parasitic inductances experience transient voltages during rapid switching, which can lead to physical damage of power switches, especially during overcurrent fault conditions.
Innovation Solution
An electronic circuit using a microcontroller unit and a less complex gate driver to generate a gate driver input signal that toggles between two voltages, providing an intermediate voltage to the gate input of the power switch during shutdown, thereby reducing overshoot and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If power switches are shut off very quickly during overcurrent fault conditions, then productivity is improved, but transient voltages are generated that can physically damage the power switches
Solution Approach 1:
The gate driver input signal is configured to toggle during a third period of time between a first voltage and a second voltage, causing the gate driver output signal to provide an intermediate voltage that is less than the third voltage during the third period of time. This preliminary action reduces the voltage overshoot before it can cause damage to the power switch.
2Reliability
If complex gate drivers are used to reduce transient voltages, then reliability is improved, but device complexity increases
Solution Approach 1:
An intermediate voltage is introduced as a mediator between the full voltage and zero voltage states. The gate driver input signal toggles between voltages to cause the gate driver output signal to provide this intermediate voltage during the third period of time, which is sufficient to reduce transient voltage overshoot but does not require a fully complex gate driver design.
Solution Approach 2:
The voltage parameter of the gate driver output signal is dynamically changed by toggling the input signal between different voltage levels. This causes the output signal to provide an intermediate voltage level that is less than the full third voltage, effectively reducing transient overshoot through parameter modulation rather than complex circuitry.
Data Source
AI summary
An electronic circuit for controlling a power switch having a gate input, includes a signal generator configured to generate a gate driver input signal. The gate driver input signal has a first voltage during a first period of time, a second voltage during a second period of time, and toggles between the first voltage and the second voltage during a third period of time. The electronic circuit also includes a gate driver configured to receive the gate driver input signal and to provide a gate driver output signal based on the gate driver input signal. The signal generator is configured to cause the gate driver input signal to toggle during the third period of time such that the gate driver output signal has a third voltage during the second period of time, and an intermediate voltage that is less than the third voltage during the third period of time.