What Are Thyristors and What Types Are There?

Posted on September 8, 2022 David Atkinson Aviation

Thyristors are small electronic elements that have been around since the 1950s, and they are often relied on for the means of managing significant amounts of voltage and power. Serving various roles, thyristors can be found in electric power control devices, electric motor speed controls, light dimmers, and much more. While thyristors once primarily acted as an element that turns devices through current reversal, they now are able to turn devices on and off with the use of a control gate signal. With the diverse applications of thyristor components, it can be useful to have a general understanding of their design and functionality.

A typical thyristor will be a four layer solid-state semiconductor device, meaning that it will have both P- and N-type materials. For the design, an anode and cathode exist on two sides of the device, while the middle is the gate. When the gate receives a triggering current, it will begin conducting electricity until the thyristor device reaches a forward bias state. Under such conditions, the thyristor may be understood as a type of bistable switch. A standard thyristor will have three leads, two of which control a large amount of current through the use of the third lead and a combination of a small amount of current with the large supply. This process is known as control lead, and when the potential difference between the two leads reaches the breakdown voltage limit, the thyristor can act as a switch.
As stated before, thrystors feature three terminals, those of which are the anode, cathode and gate. Additionally, thyristors also act in three states based on operational conditions. The reverse blocking mode is where the diode will block any voltage that is applied. Meanwhile, the forward blocking mode is a state where voltage is applied in a direction that allows the diode to begin conducting. Nevertheless, conduction will not begin unless the thyristor becomes triggered. The forward conducting mode is the final state, and this is reached when the thyristor is triggered. Upon being triggered, the thyristor will allow current to flow through the device until a threshold value known as the “holding current '' is attained by the forward current falling below it.
There are many types of thyristors that one may take advantage of based on their particular needs, and options include silicon controlled thyristors, gate turn-off thyristors, emitter turn-off thyristors, reverse conducting thyristors, bidirectional triode thyristors, MOS turn-off thyristors, fast switching thyristors, light-activated silicon controlled rectifiers, and many others. Additionally, thyristor circuits can either be DC or AC types as well. With a DC thyristor circuit, connection can be made with a DC supply for the means of managing larger DC loads and current. One major advantage of this set-up is that it allows for the thyristor to act as a switch with high current gain. As such, the thyristor can utilize a small gate current to govern a large amount of anode current. With an AC thyristor circuit, connection is made to an AC supply for management. In this setting, the thyristor will cause automatic shut-offs every half cycle as a result of its reverse biased condition.
When shopping around for thyristors, it is very important to consider what you will need from them so that the right choice can be made. Additionally, like all other parts, thyristors have finite service lives, meaning that they should be inspected, tested, and replaced on a set basis as recommended by manufacturers or regulations. Once you determine which components are best for your projects, let the experts at ASAP Parts 360 help you secure all you require with competitive pricing and rapid lead times.
ASAP Parts 360 is a leading distributor of parts that cater to a wide range of industries, presenting customers with over 2 billion new, used, obsolete, and hard-to-find parts that are ready for purchase at any time. With our online RFQ service, customers can obtain quotes for their comparisons with ease, and our team does its best to utilize all provided information to best cater to needs and restrictions. Additionally, we work around the clock for your requirements, so you can always reach us by phone or email at any time. Kick-off the purchasing process today and see how we at ASAP Parts 360 can operate as your strategic sourcing partner.

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