Analysis and Comparison of Turn-off Active Gate Control Methods for Low-Voltage Power MOSFETs With High Current Ratings

An analysis and improvement of the switching behavior of low-voltage power MOSFETs with high current ratings is presented. At turn-off, a high overvoltage arises for power MOSFETs. An improvement can be achieved by means of lowering the current slope via the driving stage during switching. Likewise, the current slope can exceed the required limits despite high gate resistances. These problems are of major concern for low-voltage power MOSFETs and can be solved via the driving stage. Thus, turn-off active gate control methods are analyzed and their performance is investigated focusing on reducing the overvoltage at turn-off under the precondition of only a minor increase of switching losses. With only a small number of additional components, a remarkable reduction of turn-off losses is achieved. Thus, these methods are well suited to industrial applications. The control concepts are experimentally compared to a basic gate drive circuit.