I will try to explain you the structure and working principle of thyristors used in fast switching duty in power electronics circuits. Thyristors are made up of four semiconductors of type P and type N. Thyristors are abbreviated as SCR, which is the initials of the words Silicon Controlled Rectifier.
What is a thyristor?
A thyristor is a four-layer semiconductor device, consisting of alternating P-type and N-type materials (PNPN). A thyristor usually has three electrodes: an anode, a cathode and a gate, also known as a control electrode.
The most common type of thyristor is the silicon-controlled rectifier (SCR). When the cathode is negatively charged relative to the anode, no current flows until a pulse is applied to the gate. Then, the SCR conducts current until the voltage between the cathode and anode is reversed or reduced below a certain threshold or holding value. Using this type of thyristor, large amounts of power can be switched or controlled using a small triggering current or voltage.
Devices using alternating current can be turned on and off by sending a signal to the control gate. This device is called a gate turn-off, or GTO, thyristor. Previously, thyristors needed the current to be reversed to turn off, making them difficult to use with direct current systems.
Thyristors are useful in switching applications because they can be fully on or off. This two-state capability differs from transistors, which operate in between on and off states, waiting for a signal to conduct current.
Applications for thyristors
Thyristors support high voltages and possess a simplified approach to switching on and off states. As a result, they are used for the following applications:
speed controls;
light dimmers;
camera flashes; and
various types of circuits, such as inverter, logic and timer circuits.
A thyristor also can function as a circuit breaker in device power circuits. They prevent power supply disruptions by connecting a Zener diode at the thyristor gate. When power supply voltage levels exceed the Zener voltage, the thyristor turns off the power supply output to the ground and activates circuit breakers or fuses upstream from the power supply. This is called a crowbar effect and protects devices being served by the power supply from damage.
I will try to explain you the structure and working principle of thyristors used in fast switching duty in power electronics circuits. Thyristors are made up of four semiconductors of type P and type N. Thyristors are abbreviated as SCR, which is the initials of the words Silicon Controlled Rectifier.
What is a thyristor?
A thyristor is a four-layer semiconductor device, consisting of alternating P-type and N-type materials (PNPN). A thyristor usually has three electrodes: an anode, a cathode and a gate, also known as a control electrode.
The most common type of thyristor is the silicon-controlled rectifier (SCR). When the cathode is negatively charged relative to the anode, no current flows until a pulse is applied to the gate. Then, the SCR conducts current until the voltage between the cathode and anode is reversed or reduced below a certain threshold or holding value. Using this type of thyristor, large amounts of power can be switched or controlled using a small triggering current or voltage.
Devices using alternating current can be turned on and off by sending a signal to the control gate. This device is called a gate turn-off, or GTO, thyristor. Previously, thyristors needed the current to be reversed to turn off, making them difficult to use with direct current systems.
Thyristors are useful in switching applications because they can be fully on or off. This two-state capability differs from transistors, which operate in between on and off states, waiting for a signal to conduct current.
Applications for thyristors
Thyristors support high voltages and possess a simplified approach to switching on and off states. As a result, they are used for the following applications:
speed controls;
light dimmers;
camera flashes; and
various types of circuits, such as inverter, logic and timer circuits.
A thyristor also can function as a circuit breaker in device power circuits. They prevent power supply disruptions by connecting a Zener diode at the thyristor gate. When power supply voltage levels exceed the Zener voltage, the thyristor turns off the power supply output to the ground and activates circuit breakers or fuses upstream from the power supply. This is called a crowbar effect and protects devices being served by the power supply from damage.
No comments:
Post a Comment