Gate Drive Circuit Topology for Surge Voltage and Miller Period Control
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Solution Overview
Problem
The reliability of semiconductor breakers is reduced due to surge voltages caused by quick current interruptions, which can break the semiconductor breaker, and slow current interruptions that extend the Miller period, leading to overcurrents and potential breaker failure.
Innovation Solution
A gate drive circuit is designed with multiple parallel circuit paths, including a first circuit path with a gate resistor, a second circuit path with a capacitor and resistor in series, and a third circuit path with a larger capacitor and resistor in series, to control surge voltages and shorten the Miller period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If current is quickly interrupted in a semiconductor breaker, then current interruption speed is improved, but surge voltage increases and may break the semiconductor breaker
Solution Approach 1:
The patent introduces a gate drive circuit as an intermediary device between the control signal and the power transistor. This circuit actively manages the gate voltage waveform to control the current interruption process, mediating between the need for quick interruption and the need to limit surge voltage. The gate drive circuit shapes the voltage applied to the gate, ensuring controlled switching that limits parasitic inductance effects.
Solution Approach 2:
The patent changes the gate voltage parameters dynamically during the switching process. By controlling the gate voltage waveform shape, duration, and magnitude, the system optimizes the trade-off between switching speed and surge voltage. The gate drive circuit adjusts voltage parameters to achieve fast current interruption while keeping surge voltage within safe limits.
2Object-affected harmful factors
If current is slowly interrupted in a semiconductor breaker, then surge voltage is reduced, but Miller period extends and overcurrent may break the semiconductor breaker
Solution Approach 1:
The gate drive circuit dynamically changes gate voltage parameters to optimize both surge voltage control and Miller period management. By adjusting voltage magnitude and waveform shape, the system achieves controlled current interruption that limits both surge voltage and overcurrent duration, improving reliability.
Solution Approach 2:
The gate drive circuit incorporates feedback mechanisms to monitor the switching process and adjust gate voltage accordingly. This feedback control ensures that the Miller period is managed effectively, preventing overcurrent conditions while maintaining appropriate current interruption speed.
3Object-affected harmful factors
If gate resistor value is increased to reduce surge voltage, then surge voltage control is improved, but Miller period extends and overcurrent risk increases
Solution Approach 1:
Instead of using a fixed gate resistor value, the patent employs a gate drive circuit that dynamically changes gate voltage parameters. This active control approach achieves surge voltage reduction without the adverse effects of increased Miller period and overcurrent risk associated with high-value resistors.
Solution Approach 2:
The patent replaces the passive mechanical/resistive approach (fixed gate resistor) with an active electronic control system (gate drive circuit). This substitution enables dynamic parameter adjustment, achieving better performance than static resistor-based solutions by independently controlling voltage and current waveforms.
Data Source
AI summary
A gate drive circuit includes: an input terminal; a first circuit path inserted into a line connecting the input terminal and a gate of a power transistor; a second circuit path connected in parallel to the first circuit path; and a third circuit path connected in parallel to the second circuit path. The first circuit path includes a gate resistor (Rgon). The second circuit path includes a first capacitor and a first resistor connected in series. The third circuit path includes a second capacitor and a second resistor connected in series. The second capacitor has a capacitance value greater than a capacitance value of the first capacitor. The second resistor has a resistance value greater than a resistance value of the first resistor. The gate resistor (Rgon) has a resistance value greater than the resistance value of the second resistor.