A Self-Regulating Method for IGBT Turn-Off Peak Voltage Control With Turn-Off Characteristics Improvement

Abstract

In hard-switching applications, insulated gate bipolar transistors (IGBTs) always suffer from harmful turn-off peak voltages. To switch the devices safely, it is a common practice to use large enough drive resistances in conventional gate drives (CGD). This, however, slows down the turn-off transients and increases switching losses. Many other measures have been proposed in the literature to limit the peak voltage but they cannot apply direct or accurate control, making the voltage margin of IGBT in use still large. In this article, a novel self-regulating peak voltage control (SRPVC) method based on active gate drive (AGD) is proposed. The SRPVC method is the first developed and reported method that can control the peak voltage in a direct and accurate way regardless of commutation conditions. The SRPVC has high simplicity. By applying independent control on turn-off $\text{d}i/\text{d}t$ , the SRPVC can produce desired voltage spikes with small drive resistance under different switching conditions. Hence, the SRPVC can reduce the turn-off delays and losses to the utmost without increasing peak voltages. The control ability, accuracy and switching characteristics improvement with SRPVC are validated experimentally on an Infineon IGBT module FF300R12ME4. The experimental results show that under identical peak voltage, the SRPVC can realize up to 53% turn-off delay and 28% loss reduction under various load currents compared with CGD.

Keywords

• IGBT
• turn-off peak voltage
• active gate drive
• control accuracy
• turn-off characteristics improvement