IGBT Gate Driver Circuit With Slope Control for Low Noise Switching
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Solution Overview
Problem
Conventional driver circuits for insulated gate power devices face challenges in reducing losses and noises, especially at high temperatures, and require additional components like capacitors and resistors, increasing manufacturing costs and complexity.
Innovation Solution
A driver circuit that includes a slope setting circuit and an operational amplifier to adjust the gate voltage waveform of an insulated gate device, allowing for high or reduced driving capability in different stages of turn-on, without the need for a series circuit of a resistor and capacitor, and uses a constant current supply to reduce temperature dependence and component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a series circuit of capacitor and resistor is connected to the gate of insulated gate device, then the driving capability can be adjusted in different stages, but the number of components increases and manufacturing cost increases
Solution Approach 1:
The patent extracts the waveform adjustment function from external RC circuits and integrates it into the driver circuit itself using an operational amplifier with adjustable gain. This eliminates the need for separate capacitor and resistor components while maintaining the ability to adjust driving capability in different stages of the turn-on process.
Solution Approach 2:
The patent merges the waveform generation and gain adjustment functions into a single operational amplifier-based circuit. The slope setting circuit and operational amplifier work together to provide stage-adjustable driving capability without requiring separate RC timing circuits, thereby reducing component count while maintaining functionality.
2Device complexity
If conventional driver circuit with fixed on-resistance is used, then the circuit is simple, but losses and noises increase at high temperatures
Solution Approach 1:
The patent introduces dynamic control of the driving signal by using an operational amplifier with adjustable gain that can adapt to different operating conditions. The circuit transitions from a fixed on-resistance approach to a dynamic gain control system that optimizes the charging current based on the stage of turn-on and temperature conditions, thereby reducing losses and noises while maintaining circuit simplicity.
Solution Approach 2:
The patent changes the key parameter from fixed on-resistance to variable gain of the operational amplifier. By adjusting the gain parameter dynamically during the turn-on process and based on temperature conditions, the circuit achieves optimal performance across different operating conditions without significantly increasing complexity.
3Speed
If high driving capability is used throughout the turn-on process, then the gate voltage rises quickly, but the turn-on gradient becomes too steep causing noises
Solution Approach 1:
The patent segments the turn-on process into distinct stages (initial stage, intermediate stage, and final stage) and applies different driving capabilities to each stage. The operational amplifier's gain is adjusted dynamically to provide high driving capability in the initial stage for fast voltage rise, then reduces gain in the intermediate stage to control the turn-on gradient and minimize noises, and finally increases gain again in the final stage to complete the turn-on quickly.
Solution Approach 2:
The patent implements periodic adjustment of the driving capability during the turn-on process by using control circuits that monitor the gate voltage level and adjust the operational amplifier gain accordingly. This periodic modulation of the driving signal ensures optimal performance at different phases of the turn-on process while minimizing harmful effects.
Data Source
AI summary
A driver circuit facilitates reducing noises and losses and improving the driving performances thereof without connecting a series circuit of capacitor and a resistor to the gate of IGBT. The driver circuit includes a slope setting circuit that sets the gate voltage waveform of IGBT; and an operational amplifier that includes a non-inverting input terminal, to which an output voltage V* from slope setting circuit is inputted, and an inverting input terminal, to which a divided voltage Vgsf divided by resistors is inputted; and the operational amplifier outputs an output voltage Vout, proportional to the difference between the output voltage V* and the divided voltage Vgsf, to the gate of IGBT.