Electric Switches for High Voltage Control in Power Generation and Distribution

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ELECTRICAL SWITCHES TO CONTROL HIGH VOLTAGE DURING GENERATION AND
DISTRIBUTION OF ELECTRIC POWER
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PROBLEM DEFINITION
Which electrical switches like Thyristor, IGBT, or MOSFET would be appropriate for control of
high voltage during generation and distribution of electric power?
LITERATURE REVIEW
There are four different ways in which a researcher can determine the appropriate electrical
switch that can be used in controlling high voltage during generation and distribution of electric
power: using Cost, reliability, turn ON and OFF speed of the switch, voltage handling capacity,
efficiency of the equipment, and safety measures.
Efficiency
The IGBTs are designed specifically to turn OFF and ON rapidly since its frequency of pulse
repetition normally gets into the ultrasonic range. MOSFETs have the benefit of greater
efficiency and higher commutation speed during low operation voltage only hence they are not
suitable for controlling high voltage during generation and distribution of electric power
(Doohyung & Kim, 2012). The efficiency of Thyristor is definitely higher compared to the
efficiency of IGBT in case a comparison between a Voltage Source Inverter (with 6 IGBT and a
Current Source Inverter (with 6 SCR). The voltage drop between Thyristor and IGBT is not very
significant. Therefore, both IGBT and Thyristor have higher efficiency than MOSFET and the
two can both be used in controlling high voltage during generation and distribution of electric
power (Bauer, et al., 2012).
Cost

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An IGBT, Infineon IGW60T120 rated 60A and 1200V costs about $10 while 32A 2500V cost
$36 while a MOSFET of 60A 800V cost 20$. Thyristor 50A 1200V cost $75 making the IGBT
the cheapest for higher ratings than both MOSFET and Thyristor.
Turn ON and OFF Speed
The major disadvantage of IGBT is that holes are injected into the n-layer which is a high
resistive layer hence resulting in increased conductivity with the n-layer which minimize the
total on-state voltage of this switching device. The on-state voltage reduction of IGBT makes an
IGBT to experience slower switching during turn-on. In the case of MOSFETs, this problem is
solved by halting the electron flow by minimizing the gate-emitter voltage below the voltage of
gate threshold (Karas & Andy, 2019). Thyristor has been supplanted by the IGBTs because of
the faster switching capability. This is because Thyristor operates at a higher plasma density and
have approximately half the on-state voltage. Because of the superior switching characteristic of
IGBT despite slower turn-on, this device is far much superior to both MOSFET and Thyristor
(Shoji, et al., 2016).
Voltage Handling Capacity
The IGBT is a semiconductor device that combines the gate drive characteristics of a MOSFET
and the output characteristic of a bipolar transistor. Therefore, the IGBT is a device with
minority carrier with high current-carrying capacity and high input impedance compared to
MOSFET. The voltage drop between Thyristor and IGBT is not very significant. Thyristor, on
the other hand, can control a relatively large voltage and power compared to the IGBT which has
considerably weaker forward voltage drop compared to the other two switching devices.
Therefore in terms of voltage handling capability, Thyristor is superior to both MOSFET and