High-power Gate Turn-off Thyristors Research Articles

Analogue Behavioral Modeling of GTO

An analog behavioral model of high power gate turn-off thyristor (GTO) is developed in this paper. The fundamental methodology for the modeling of this power electronic circuit is based on the use of the realistic diode consideration of non-linear junctions. This modeling technique enables to perform different simulations taking into account the turn-on and turn-off transient behaviors in real-time. The equivalent circuits were simulated with analog software developed in our laboratory. It was shown that the tested simple and compact model allows the generation of accurate physical characteristics of power thyristors under dynamic conditions. The model understudy was validated with analog simulations based on operational amplifier devices.

Gate-assisted reverse and forward recovery of high-power GTOs in series resonant DC-link inverters

The series resonant DC-link inverter is an attractive circuit topology for interfacing a DC current with a three-phase AC system. It uses gate turn-off thyristors (GTOs) as semiconductor switches. The conventional solution requires an additional series diode to perform the turn off process and to enable forward recovery of the GTO. This paper uses a single GTO along with a special gate drive to provide reverse and forward recovery. A new device testing circuit was designed to create the same electrical and thermal stresses as in a series resonant DC-link inverter. Experimental results using 2000 A GTOs at 26 kHz switching frequency demonstrate that the total device losses are reduced, while the hold-off time is slightly increased. The new single-device solution makes resonant switching attractive for very high-power applications.

Analysis of GTO-based static VAr compensators

The growing availability of high-power gate turn-off thyristors (GTOs) has meant that power electronic convertor circuits can be manufactured with the ability to both absorb and generate reactive power. These circuits constitute the next generation of static VAr compensators (SVCs) which may eventually supersede the conventional thyristor-controlled reactors (TCRs) and thyristor-switched capacitors (TSCs) used in power systems at present. The paper gives an analysis of both 6-pulse and 12-pulse GTO-SVCs based on voltage-source convertor circuits, and equations are derived that describe the performance of each circuit. In addition, the conditions leading to circuit resonances are discussed together with possible methods of avoiding the problems.

Turn-On and Turn-Off Characteristics of a 4.5-kV 3000-A Gate Turn-Off Thyristor

A 4.5-kV 3000-A gate turn-off (GTO) thyristor has been developed for use in high-power motor drive control equipment such as inverters and choppers. The high gate turn-off current of 3000 A is achieved by decreasing the variation of on-state voltages as well as turn-off times between segments which compose the GTO thyristor. This idea is supported by observation of infrared radiation during the turn-off process in the parallel operation of two segments with different on-state voltages or turn-off times. The parallel operation behavior is well simulated by a two-dimensional numerical simulation. Such design considerations and electrical characteristics of the newly developed high-power GTO thyristor are described. The device has a forward blocking capability of 4.5 kV, a maximum gate turn-off current of 3000 A, on-state voltage of 3.0 V at 3000 A, turn-on time of 10 ?s, and turn-off time of 25 ?s.

High Power Gate Turn-Off Thyristors

High power gate turn-off thyristors (GTO's) are studied because of their gate turn-off capability in addition to the usual thyristor characteristics. GTO development, however, has suffered from difficulty in attaining high current gate turn-off capability. From the experimental results, maximum gate turn-off current IATO depends upon a factor (VJ1/ρSPB), as well as the n-base resistivity. On the basis of this principle success was achieved in realizing devices with more than 600 amperes of IATO. Various considerations were made for GTO design, together with numerous experiments in fabrication and characterization.