Page 130 - Rashid, Power Electronics Handbook

8

MOS Controlled Thyristors

(MCTs)

S. Yuvarajan, Ph.D. 8.1 Introduction ...................................................................................... 117
Department of Electrical
Engineering, North Dakota 8.2 Equivalent Circuit and Switching Characteristics ..................................... 118
State University, 8.2.1 Turn-on and Turn-off
P.O. Box 5285, Fargo, 8.3 Comparison of MCT and Other Power Devices....................................... 119
North Dakota 58105-5285, 8.4 Gate Drive for MCTs .......................................................................... 119
USA
8.5 Protection of MCTs ............................................................................ 120
8.5.1 Paralleling of MCTs 8.5.2 Overcurrent Protection
8.6 Simulation Model of an MCT .............................................................. 120
8.7 Generation-1 and Generation-2 MCTs ................................................... 121
8.8 N-channel MCT ................................................................................. 121
8.9 Base Resistance-Controlled Thyristor ..................................................... 121
8.10 MOS Turn-Off Thyristor ..................................................................... 121
8.11 Applications of PMCT......................................................................... 122
8.11.1 Soft-switching 8.11.2 Resonant Converters
8.12 Conclusions....................................................................................... 123
8.13 Appendix .......................................................................................... 123
8.13.1 Description
References ......................................................................................... 124

8.1 Introduction The power MOSFET has several advantages such as high
input impedance, ease of control, and higher switching speeds.
The ef®ciency, capacity, and ease of control of power conver- Lower current density and higher forward drop limited the
ters depend mainly on the power devices employed. Power device to low-voltage and low-power applications. An effort to
devices, in general, belong to either bipolar-junction type or combine the advantages of bipolar junction and ®eld-effect
®eld-effect type and each one has its advantages and disad- structures has resulted in hybrid devices such as the insulated
vantages. The silicon controlled recti®er (SCR), also known as gate bipolar Transistor (IGBT) and the MOS controlled
a thyristor, is a popular power device that has been used over thyristor (MCT). While an IGBT is an improvement over a
the past several years. It has a high current density and a low bipolar junction transistor (BJT) using a MOSFET to turn on
forward voltage drop, both of which make it suitable for use in and turn off current, an MCT is an improvement over a
large power applications. The inability to turn off through the thyristor with a pair of MOSFETs to turn on and turn off
gate and the low switching speed are the main limitations of current. The MCT overcomes several of the limitations of the
an SCR. The gate turn-off (GTO) thyristor was proposed as an existing power devices and promises to be a better switch for
alternative to SCR. However, the need for a higher gate turn- the future. While there are several devices in the MCT family
off current limited its application. with distinct combinations of channel and gate structures [1],

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Copyright # 2001 by Academic Press.
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