What is the IGBT buffer circuit commonly used?

Power electronic devices have four operating states: on, off, off and off. The off and on states respectively bear high voltage and high current. In the process of on and off, the switching devices may simultaneously bear overvoltage and overcurrent, too much di/dt, du/dt and too much instantaneous power. Therefore, in order to prevent the device from being damaged due to the high voltage and large current, the buffer circuit is added to the circuit to turn off the buffer circuit to absorb the turn-off overvoltage and commutation overvoltage of the device, inhibit du/dt and reduce the turn-off loss. The buffer circuit can inhibit the current overshoot and di/dt when the device is opened to reduce the opening loss of the device.

In modern life, IGBT as a fully controlled device has been more and more widely used, with the continuous improvement of its power and voltage level, it is particularly important to protect it. The peak voltage of IGBT at shutdown is mainly caused by the existence of distributed inductance in the main loop. Too high peak voltage will not only damage IGBT, but also lead to misdirection of IGBT. Therefore, it is essential to set buffer circuit to absorb the peak voltage.

The following are two - level and three - level buffer circuits in the inverter topology.