Gate Drive Circuit for Fast Turn-On Without Erroneous Switching
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Solution Overview
Problem
Existing gate driving circuits face issues with erroneous turn-on and slow turn-on speed when switching elements transition from OFF to ON, particularly in high-speed switching scenarios, leading to increased diode loss due to simultaneous switching of upper and lower arms during dead time.
Innovation Solution
A driving circuit that includes a negative-voltage power supply and a voltage changing unit to apply a negative voltage when switching from ON to OFF, and rapidly change the gate voltage to be higher than the negative voltage before switching to ON, using a push-pull circuit, resistors, and capacitors to manage the gate voltage effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 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 gate voltage is dynamically adjusted based on the switching state: a negative voltage is applied during the OFF state to prevent erroneous turn-on, and then rapidly switched to a positive voltage during the ON state to enable fast turn-on. This dynamic voltage adjustment resolves the contradiction by applying different voltages at different times.
Solution Approach 2:
The gate voltage is periodically switched between negative and positive levels synchronized with the switching element's operation cycle. During the OFF period, negative voltage suppresses erroneous turn-on; during the ON period, positive voltage enables rapid turn-on, creating a periodic voltage application pattern that addresses both requirements.
2Productivity
If high-speed switching is performed to reduce loss, then productivity is improved, but erroneous turn-on occurs more frequently
Solution Approach 1:
A negative voltage is applied to the gate in advance during the OFF state to create a protective barrier against erroneous turn-on before high-speed switching occurs. This preliminary negative voltage application counteracts the tendency toward erroneous turn-on that arises during high-speed switching operations.
Solution Approach 2:
The gate voltage is dynamically adjusted based on the switching state: a negative voltage is applied during the OFF state to prevent erroneous turn-on, and then rapidly switched to a positive voltage during the ON state to enable fast turn-on. This dynamic voltage adjustment resolves the contradiction by applying different voltages at different times.
3Reliability
If the gate voltage remains at negative level after turn-on, then erroneous turn-on is suppressed, but turn-on speed decreases
Solution Approach 1:
The gate voltage is periodically switched between negative and positive levels synchronized with the switching element's operation cycle. During the OFF period, negative voltage suppresses erroneous turn-on; during the ON period, positive voltage enables rapid turn-on, creating a periodic voltage application pattern that addresses both requirements.
Solution Approach 2:
The gate voltage is dynamically adjusted based on the switching state: a negative voltage is applied during the OFF state to prevent erroneous turn-on, and then rapidly switched to a positive voltage during the ON state to enable fast turn-on. This dynamic voltage adjustment resolves the contradiction by applying different voltages at different times.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution suppresses erroneous turn-on and increases turn-on speed, reducing diode loss by optimizing the gate voltage transitions and preventing simultaneous switching of upper and lower arms.
Implementation Method 1
The negative-voltage power supply applies a negative voltage as the voltage to the control terminal when the switching element is switched from the ON state to the OFF state
Implementation Method 2
The voltage changing unit changes the voltage immediately before the switching element is switched from the OFF state to the ON state to be higher than the negative voltage from the negative-voltage power supply
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A driving circuit applies a voltage to a switching element (1) to switch between an ON state and an OFF state. The switching element (1) includes a control terminal, a high-potential terminal, and a low-potential terminal, and is switched between the ON state in which a current flows between the high-potential terminal and the low-potential terminal and the OFF state in which the current does not flow therebetween, 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 (5) and a voltage changing unit (R2, R3, C1). The negative-voltage power supply (5) applies a negative voltage as the voltage to the control terminal when the switching element (1) is switched from the ON state to the OFF state. The voltage changing unit changes the voltage immediately before the switching element (1) is switched from the OFF state to the ON state to be higher than the negative voltage from the negative-voltage power supply (5) immediately after the switching element (1) is switched from the ON state to the OFF state.