UNIT - I INTRODUCTION to THYRISTORS and OTHER POWER ELECTRONICS
1 POWER ELECTRONICS UNIT - I INTRODUCTION To THYRISTORS AND OTHER POWER ELECTRONICS UNIT - I Power Electronics & its Roll : Power electronics is a technology that deals with the conversion and control of electrical power with high-efficiency switching mode electronic devices for a wide range of applications. Power electronics makes it possible to transport electricity over long distances with minimum losses, which is accomplished by Power Converters. Power Converters convert alternating current (AC) into high-voltage direct current (HVDC) and vice-versa Power Electronics Devices are also used many applications like speed control of AC / DC Motors, electrochemical process, heating and lighting control, electronic welding, power line volt–ampere reactive (VAR) and harmonic compensators, high-frequency (HF) heating, and motor drives. Silicon Controlled Rectifier ( SCR ) / Thyristor A silicon controlled rectifier is a four-layer solid state current-controlling device which control high Voltage and Power. A SCR is device / component have three terminals namely anode (A), cathode (K), Gate (G), four Layers P-N-P-N, and three Junctions J 1, J 2, J 3 . It allows the current in one direction from Anode to Cathode only and the Gate controls the flow of current between the Anode and Cathode. The primary function of SCR / Thyristor is to control electric power and current by acting as a switch. Figure shows the Construction & Symbol of SCR: 2 POWER ELECTRONICS UNIT - I INTRODUCTION To THYRISTORS AND OTHER POWER ELECTRONICS SCR V-I Characteristics Forward Characteristics When Anode is positive with respect to Cathode, the curve between V and I is called the forward characteristics.
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