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Talking about IGBT driver expanding current
03-20
Power semiconductor drive circuit is an important sub-category of integrated circuits with powerful functions. In addition to providing drive level and current, drive ICs for IGBT often have drive protection functions, including desaturation short-circuit protection, undervoltage shutdown, Miller Clamping, two-level shutdown, soft shutdown, SRC (slew rate control), etc., the products also have different levels of insulation performance. However, as an integrated circuit, its package determines the maximum power consumption. Some driver IC output currents can reach more than 10A, but they still cannot meet the driving requirements of high-current IGBT modules. This article will discuss the IGBT drive current and current expansion issues.
How to Extend Driver Current
When it is necessary to increase the driving current, or when driving an IGBT with large current and large gate capacitance, it is necessary to expand the current for the driving integrated circuit.
Bipolar Transistor
Using complementary emitter follower to achieve current extension is the most typical design of IGBT gate driver. The output current of the emitter follower transistor is determined by the DC gain hFE or β of the transistor and the base current IB. When the current required to drive the IGBT is greater than IB *β, at this time, the transistor will enter the linear working area, and the output drive current will be insufficient. At this time, the charging and discharging speed of the IGBT capacitor will slow down, and the IGBT loss will increase. The specific calculation case is given at the end.