Electrical and Electronics

What is Power Transistor? Power Transistor posses controlled characteristics. These are turned ON when current signal is given to base. The transistor will be in ON condition until control signal is present. When the control is removed, the power transistor is turned OFF. Power Transistor can be classified into four types, Bipolar Junction Transistor(BJT)  Metal Oxide Semiconductor Field Effect Transistor(MOSFET) Insulated Gate Bipolar Transistor(IGBT) Static Induction Transistor(SIT) Bipolar Junction Transistors(BJT) A BJT is a three-layer, two junction, npn or pnp semiconductor device. It can be classified into two types,  PNP Transistor - Two p region sandwiched by one n region NPN Transistor - One p region sandwiched by two n region The term 'bipolar' denotes, the current flow in the device is due to the movement of both holes and electrons.Collector, Base, Emitter are the three terminals present in BJT. NPN Transistors are used widely in handling high-voltage and high-cur...

What is Power Diode? A Power diode is two-terminal p-n junction device. They have large power, voltage and current handling capabilities than normal signal diodes. The frequency response(switching speed) is low compared to signal diodes. Diode acts as switch to perform various functions such as switches in rectifiers, freewheeling in switching regulators, charge reversal of capacitor and energy transfer between components, voltage isolation, energy feedback from the load to the power source and trapped energy recovery. The diode is said to be forward biased when the anode potential is positive with respect to cathode and reverse biased when cathode potential is positive with respect to anode. Diode conducts when it is forward biased. A conducting diode has small forward voltage drop across it and the magnitude of this drop depends on the manufacturing process and junction temperature. Under reverse biased condition, the diode does not conduct and a small reverse current (leakage curren...

POWER ELECTRONICS Power Electronics deals with the use of electronics for the control and conversion of large amount of electrical power. It constitute a vast, complex and interdisciplinary subject that has gone through rapid technological evolution. History A paper entitled " PNPN Transistor switches"( https://ieeexplore.ieee.org/document/4052177 ) was published by four engineers of Bell Telephone Laboratory, USA. It triggered intensive research on PNPN devices. Hence, in 1957 , Gordon Hall of General Electric Company, USA, developed the three terminal PNPN based semiconductor device called as Silicon Controlled Rectifier(SCR). Later on many power devices were developed similar to SCR. Power Electronic system  Power Electronic Converters Converter uses a matrix of power semiconductor switches to convert electrical power at high efficiency. The converter system is composed of switches, reactive components(L, C) and transformers. These converters are classified into, Phase Co...