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A unique kind of thyristor, such as a gate turn off thyristor (GTO), is a high-power (1200V AC, for example) semiconductor device. General Electric was the one who created it.
GTOs are fully controlled switches that may be turned on and off by their gate lead, as opposed to typical thyristors. Switches with a standard silicon thyristor (controlled rectifier) are not entirely controllable (a “fully controllable switch” can be turned on and off at will).
The gate lead can only be used to turn on thyristors; it cannot be used to turn them off. A gate signal turns on thyristors, however even after the gate signal is deleted or reverse biassed, the thyristor stays in the on state until a turn-off condition is met (which can be the application of a reverse voltage to the terminals or a decrease of the forward current below a certain threshold value known as the “holding current”).
When a thyristor is activated, or “fired,” it functions like a typical semiconductor diode. A gate signal can activate the GTO, and a gate signal with a negative polarity can turn it off.
A “positive current” pulse between the gate and cathode terminals turns the device on. There will be little voltage between the terminals because the gate-cathode functions like a PN junction.
To increase reliability, a little positive gate current must be maintained even after the turn-on phenomenon in GTOs, which is not as dependable as an SCR (thyristor).
A “negative voltage” pulse between the gate and cathode terminals turns the device off. About one-third to one-fifth of the forward current is “taken” and utilized to create a cathode-gate voltage, which in turn causes the forward current to decrease and the GTO to turn off (transitioning to the “blocking” state).
Long switch-off times are a problem with GTO thyristors; once the forward current drops, there is a long tail period during which a residual current flows until all of the device’s charge has been removed.
This limits the switching frequency to a maximum of around 1 kHz. However, it should be noted that a GTO’s turn-off time is around ten times faster than that of an equivalent SCR.
GTO thyristors are often built from a large number (hundreds or thousands) of tiny thyristor cells connected in parallel to help with the turn-off operation.
The Global Gate Turn Off Thyristor (GTO) market accounted for $XX Billion in 2022 and is anticipated to reach $XX Billion by 2030, registering a CAGR of XX% from 2023 to 2030.
A Gate Turn Off Thyristor (GTO) is a type of thyristor that may be turned off by passing a current through the gate in the opposite direction of how it would normally be applied to turn it on.
Low conduction losses are the focus of GTO design. For the majority of applications, the usual on-off switching frequency falls between 200 and 500 hertz. GTOs are often sluggish switches by nature.
Typically, it takes 10 to 30 microseconds to get from an on state to an off one and vice versa. Snubbers, or safety networks, are necessary for the turn-on and turn-off of every GTO.
The rate of current growth is constrained by the turn-on snubber circuit, which is essentially an inductor. The GTO needs a device, which is essentially a capacitor and regulates the rate of voltage rise, in order to switch off.
Press-pack devices are used in all ABB GTOs. They are pressed into heat sinks that also act as electrical connections to the power terminals with a fair amount of force.
