Objectives
Ø
Explain and analyze the operation of both half and full wave rectifiers
Ø
Explain and analyze filters and regulators and their characteristics RECTIFIER
The SCR is the most
important special semiconductor device. This device is popular for its Forward-Conducting and Reverse-blocking characteristics.
SCR can be used in high-power devices. For example, in the central processing unit of the
computer, the SCR is used in switch mode power supply (SMPS).
I–V Characteristics of the SCR
žAs -shown in Fig. 8-5,
if the gate current is 0 mA, the critical
voltage is higher, i.e., the SCR requires more voltage to switch to the
conducting state.
ž -But as the value of gate
current increases, the critical voltage becomes lower, and the SCR switches to the conducting state at a
lower voltage.
ž -At the higher gate current IG2,
the SCR switches faster than at the lower gate current IG1, because IG2 > IG1.
Simple Applications:
ž The SCR is the
most important member of the thyristor family. The SCR is a
capable power device as it can handle thousands of amperes and volts.
ž Generally the SCR is
used in many applications such as in high power electronics, switches,
power-control and conversion mode.
ž It is also used as
surge protector.
ž Static Switch: The SCR is used as a switch for power-switching in
various control circuits.
ž Power Control: Since the SCR can be turned on externally, it can be
used to regulate the amount of power delivered to a load.
žSurge Protection: In an SCR circuit,
when the voltage rises beyond the threshold value, the SCR is turned on to
dissipate the charge or voltage quickly.
žPower Conversion: The SCR is also used for high-power conversion and
regulation. This includes conversion of power source from ac to ac, ac to dc
and dc to ac.
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