Switching Element Gate Drive with Negative Voltage Pre-Charge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In existing driving circuits, the transition from OFF to ON state for switching elements leads to erroneous turn-on and increased diode loss due to prolonged turn-on time and simultaneous switching of upper and lower arm elements, which is exacerbated by high-speed switching in hard switching states like half-bridge configurations.
Innovation Solution
A driving circuit utilizing a negative-voltage power supply and a voltage changing unit that adjusts the gate voltage to be higher than the negative voltage immediately before switching from OFF to ON, reducing turn-on time and suppressing erroneous turn-on by maintaining a negative voltage during dead time, thereby enhancing switching speed and reducing diode loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If negative voltage is applied to the gate of the switching element to suppress erroneous turn-on, then reliability is improved, but turn-on time increases
Solution Approach 1:
The voltage changing unit pre-charges the capacitor during the dead time period before the switching element is turned on. This preliminary action ensures that when the switching element needs to turn on, the capacitor is already charged to a voltage higher than the negative voltage, enabling faster turn-on while maintaining reliable suppression of erroneous turn-on during the dead time.
2Productivity
If high-speed switching is performed to reduce loss, then productivity is improved, but erroneous turn-on occurs
Solution Approach 1:
The voltage changing unit applies a voltage higher than the negative voltage to the gate during the dead time period before switching occurs. This preliminary anti-action creates a voltage buffer that prevents erroneous turn-on caused by voltage spikes or noise during high-speed switching operations, while still allowing fast switching when needed.
3Reliability
If negative voltage is applied during dead time to prevent simultaneous switching, then reliability is improved, but diode loss increases
Solution Approach 1:
The voltage changing unit pre-charges the capacitor during the dead time period. By the time the switching element needs to turn on, the capacitor is already charged to a higher voltage, reducing the voltage difference that needs to be overcome during turn-on. This reduces the turn-on time and consequently reduces diode loss, while still maintaining reliable prevention of simultaneous switching during the dead time.
Data Source
AI summary
A driving circuit applies a voltage to a switching element to switch between an ON state and an OFF state. The switching element includes a control terminal, a high-potential terminal, and a low-potential terminal, and is switched between the ON state and the OFF state depending on the voltage of the control terminal in a case in which a potential of the low-potential terminal is defined as a reference potential. The driving circuit includes a negative-voltage power supply for applying a negative voltage as the voltage to the control terminal when the switching element is switched from the ON state to the OFF state, and a voltage changing unit for changing the voltage immediately before the switching element is switched from the OFF state to the ON state to be higher than the negative voltage immediately after the switching element is switched from the ON state to the OFF state.