04-08-2012, 10:46 AM
POWER ELECTRONICS LABORATORY MANUAL
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INTRODUCTION
Power electronics deals with the application of solid state electronics for the control and
conversion of electric power.Convertion techniques require the switching ON and OFF
of power semiconductor devices. Low level electronics circuits which normally consist
of integrated circuits and discrete components generate the required gating signals for
power devices.Integrated circuits and discrete componenets are now being replaced by
microprocessors.
An ideal power device should have no switching on and off limitations in terms
of turn on time, turn off time, current and voltage handling capabilities. Power
semiconductor technology is rapidly developing fast switching power devices with
increasing voltage and current limits. Power switching devices such as power BJTS,
power MOSFETS, IGBTS, SCRs, TRIACs, and other semiconductor devices are finding
increasing applications in wide range of products. With availability of faster switching
devices the applications of modern microprocessors in synthesizing the control strategy
for gating power devices to meet the conversion specifications are widening the scope of
power electronics .
EXPERIMENT:01
STATIC CHARACTERISTICS OF SCR AND DIAC
Aim: a)To plot the static characteristics of the given SCR and find the latching and
holding current.
Equipments/Apparatus Used:
1) SCR/DIAC Module 1No
2) Ammeter 0-500mA(DC) 1No
0-50mA(DC) 1No
3) Multimeter 1No
Theory:
SCR: The Silicon Controlled Rectifier(SCR) also called the thyristor is one of the
most widely used semi controlled switching device. It has a p-n-p-n structure and 3
terminals- anode (A), cathode (K), and gate(G).
A graph of the anode current (iA) Vs anode to cathode voltage (VAK) for different
values of gate current (iG ) is called as the static characteristics.
When the SCR is reverse biased, a very small amount of reverse current in the order
of a few micro amperes flows through it.
Latching current is the minimum anode current required to turn on SCR without gate
current.
Holding current is the maximum anode current with gate being open, at which SCR
is turned off from on condition.