IGBT Gate Drive Circuit With Capacitive Bypass for Lower Turn-On Loss
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Solution Overview
Problem
Existing drive circuits for voltage-driven elements, such as IGBTs, face challenges in reducing turn-on loss without increasing the size of external capacitors, which leads to increased gate charging time and power source consumption.
Innovation Solution
The proposed drive circuit incorporates a push-pull transistor configuration with a capacitive element in parallel to the semiconductor element, utilizing a gate resistor and a condenser to efficiently charge and discharge gate-emitter and gate-collector capacitances, thereby reducing turn-on loss without enlarging the capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an external capacitor is connected between the emitter terminal and gate resistor to reduce turn-on loss, then the turn-on loss is reduced, but the gate charging time increases and power source consumption increases
Solution Approach 1:
The patent segments the capacitor function into two parts: an external capacitor connected between emitter and gate resistor for energy storage, and an internal capacitor formed by the gate-emitter junction for voltage maintenance. This segmentation allows the external capacitor to supply charge during turn-on while the internal capacitor maintains gate voltage, reducing both turn-on loss and charging time.
Solution Approach 2:
The gate resistor serves as an intermediary element that limits the charging current from the external capacitor to the gate, preventing excessive current while still allowing sufficient charge transfer. This intermediary function resolves the contradiction by enabling energy transfer without excessive charging time or power consumption.
2Loss of energy
If the external capacitor is made larger to reduce turn-on loss, then the turn-on loss is further reduced, but the gate charging time increases and consumption current increases
Solution Approach 1:
The patent divides the capacitance function between an external capacitor and the inherent gate-emitter capacitance. This segmentation allows optimal sizing of the external capacitor without requiring excessive capacity, as the internal capacitor contributes to voltage maintenance, thereby reducing power source consumption while maintaining low turn-on loss.
Solution Approach 2:
The gate-emitter junction capacitance serves itself by maintaining the gate voltage after being charged by the external capacitor. This self-service function reduces the burden on the power source and minimizes consumption current while achieving low turn-on loss without requiring a large external capacitor.
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
This configuration effectively suppresses the reduction of gate voltage and collector-emitter voltage, reducing turn-on loss and power source consumption, even when the gate-collector capacitor is large, by using a bypass current to charge the gate-emitter capacitance from the power source.
Implementation Method 1
a capacitive element connected in parallel with the first semiconductor element and configured to supply an electric charge from the power source to a portion between the gate terminal and the emitter terminal after an electric charge accumulated in the portion between the gate terminal and the emitter terminal is supplied to a portion between the gate terminal and the collector terminal
Data Source
AI summary
A drive circuit for driving a voltage-driven-type element including a gate terminal, an emitter terminal and a collector terminal includes a first semiconductor switch including an output terminal disposed between a power source for the drive circuit and the gate terminal, a first resistor disposed between the output terminal and the gate terminal and a capacitive element connected in parallel with the first semiconductor switch. The capacitive element supplies an external electric charge from the power source to a portion between the gate terminal and the emitter terminal after an internal electric charge accumulated in the portion between the gate terminal and the emitter terminal is supplied to a portion between the gate terminal and the collector terminal.