Gate Drive Circuit Switching for Low-Loss, Low-Surge Turn-Off
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor switching element drive circuits face challenges in bringing the switching time point of the gate drive condition close to an appropriate switching time point due to the large propagation delay time of analog comparators.
Innovation Solution
A semiconductor switching element drive circuit that includes a voltage-dividing resistor, a logic circuit that inverts the level of an output signal based on the divided voltage, and a switching circuit that switches the gate drive condition of the semiconductor switching element during turn-off operations based on the output signal from the logic circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switching speed of the semiconductor switching element is increased to reduce switching loss, then the switching loss is reduced, but the surge voltage increases
Solution Approach 1:
The patent applies dynamics by switching the gate drive condition between a first gate drive condition (with first gate resistance) and a second gate drive condition (with second gate resistance) during the turn-off operation. This dynamic adjustment of gate resistance allows the switching speed to be optimized at different stages: higher speed initially to reduce switching loss, then lower speed later to reduce surge voltage, thereby resolving the trade-off between switching loss and surge voltage.
2Measurement precision
If an analog comparator is used to detect the switching time point, then the switching time point can be detected, but the propagation delay time is relatively large preventing the switching time point from being brought close to the appropriate switching time point
Solution Approach 1:
The patent replaces the analog comparator (electronic measurement system) with a voltage-dividing resistor circuit that directly generates a detection signal based on voltage division. This substitution eliminates the propagation delay inherent in analog comparators, allowing the switching time point to be detected with minimal delay and brought close to the appropriate switching time point (current decrease time point).
Data Source
AI summary
An object is to provide a technique capable of bringing a switching time point of a gate drive condition close to an appropriate switching time point. A semiconductor switching element drive circuit includes a logic circuit that inverts a level of an output signal based on a divided voltage of an output voltage of a semiconductor switching element, and a switching circuit. The switching circuit switches a gate drive condition of the semiconductor switching element during a turn-off operation from a first gate drive condition to a second gate drive condition in which a switching speed is lower than that of the first gate drive condition based on the output signal from the logic circuit.