Thyristor Devices Thyristor Devices Silicon Controlled Rectifiers (SCR) Silicon Controlled Rectifiers (SCR) By: Dr. Javed Iqbal By: Dr. Javed Iqbal Class: BSc. EE, F-17 Class: BSc. EE, F-17 Army Public College of Management and Sciences, Rawalpindi Army Public College of Management and Sciences, Rawalpindi 1
Power Semiconductor Switches Power Diodes Power Transistors Thyristors 2 layer device 3 layer Device 4 layer Device Thyristor devices can convert and control large amounts of power in AC or DC systems while using very low power for control. Thyristor family includes 1- Silicon controlled switch (SCR) 2- Gate-turnoff thyristor (GTO) 3- Triac 4- Diac 5- Silicon controlled switch (SCS) 6- Mos-controlled switch (MCT) 2
INTRODUCTION SCR is most popular of thyristor family due to its Fast switching action , small size and high voltage and current ratings. It is commonly used in power electronic applications. SCR has 3 terminals (gate provides control) SCR is turned on by applying +ve gate signal when anode is +ve with repect to cathode. SCR is turned off by interrupting anode current. 3 PNPN structure Symbol
TWO TRANSISTOR MODEL OF SCR 4 Gate requires small positive pulse for short duration to turn SCR on. Once the device is on, the gate signal serves no useful purpose and can be removed.
SCR CHARACTERISTIC CURVE 5
IDEAL CHARACTERISTIC OF SCR 6
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- Fall '19
- Alternating Current, SCR