Most of the IGBT available in the market having the buffer layer in them. IGBT having the buffer layer in them are called Asymmetric IGBT(Punch-trough IGBT). Because of the presence of the n+ buffer layer in the IGBT, it unable to block the large reverse voltage, therefore the device breakdown at the lower reverse voltage. This offers the IGBT the fast switching time, as compare the symmetric configuration.
Static switch 1) Static switches use semiconductor elements such as SCR to perform the shifting of load between two power sources. 2)Circuit offers very fast switching time, usually in the range of the milliseconds. This help to maintain the uninterrupted power supply to the load. 3) The static switch consists of three parts: a) Breaker. b) SCR. c) Control system. 4) current sensing device constantly monitors the output of the switch and provide the necessary input to the control relay circuit. 5)If the AC source fails to supply the voltage to the load, the control circuit switches connection to the inverter input source. Block Diagram of the static switch is as follows: Application of the static switch: 1) The static switch is used in the UPS system.