| Abstract |
One of the main challenges originated by the use of the new power transistors in switching power converters is presented by the ever faster commutation of the semiconductor devices embedded in inductive circuits. The fast commutation leads to extremely high voltages in the circuit when transistors are turned off. In this paper, a new method using feedback techniques is presented, which is suitable to drive and protect high power transistors in commutation. This active protection allows the use of the maximum transistor safe operating area, since it prevents the drain to source voltage from rising above a prescribed value. One aditional advantage of this drive technique consists in the reduction of the turn-on time of the MOS transistor due to an inherent increase of the driving current. Other features, such as overcurrent and overtemperature protection, are also easily included in the drive circuit. The new approach permits faster, lighter and more efficient circuits, compared with the conventional clampers and snubbers (McMurray, 1979). Furthermore the proposed method can be implemented either on the same chip with the power transistor, or in a separate drive circuit and both realized in bipolar or MOS double-polysilicon technologies using the new Smart Power Techniques (Rossel and Buxo, 1985). |
