The Integrated Emitter Turn-Off Thyristor (IETO)—An Innovative Thyristor-Based High Power Semiconductor Device Using MOS Assisted Turn-Off

This paper focuses on a new realization method of an emitter turn-off thyristor (ETO). The low-inductive requirements for the unity gain turn-off capability of a gate commutated thyristor (GCT) led to bulky driver stages directly attached to the device. This, combined with the need for electrolytic capacitors, inherently leads to mechanical and thermal design problems, which significantly limit the application opportunities, as well as the device´s lifetime and reliability. The concept of the ETO overcomes the need for a capacitor bank by using MOSFETs in the cathode current path of the thyristor. The thermal limitations of the gate driver unit are attenuated by this concept, its bulky lay-out is not. The approach presented in this paper overcomes some drawbacks of the known ETO by integrating the MOSFETs into the press pack. Hereby, a significantly smaller and less complex driver design is achieved.