Theoretical syllabusweek Power electronic, electronic components which used in high power control (power diodes, thyristor and power transistors) prevision of single phase rectifier circuits. Three –phase rectifier circuits by using diodes, output voltage waveform, diode current waveform, output voltage equation in case of resistance load. Using the transistor as switch, region of operation, transistor as a switch (cutoff and saturation). Power transistor in off and on state, improvement of off and on time by using speed up capacitance, practical problem. Unijunction transistor, construction, theoretical operation, using the transistor as relaxation oscillator practical example. Operational amplifier, description of operational amplifier as aspartate component, zero detector, comparator. The use of op-amp as a stable multivibrator and a monostable multivibrator, photo conduction cells, photo diodes.

Theoretical syllabusweek Light-emitting diodes (LED), photo transistors, the use of optical comparator in power Electronic circuits. Thyristor, construction, characteristic, curve for a thyristor, thyristor conduction in forward biasing, thyristor family, thyristor representation as a double transistor circuit. Thyristor conduction methods, conduction throw the gate minimum gate current causing conduction, conduction time,conduction due to high forward voltage rectifier (dv/dt) DIAC,TRIAC characteristics, practical applications, thyristor, triggering methods, triggering on DC and AC current, pulse triggering types. Thyristor triggering circuit, DC and AC triggering circuits. Pulse current triggering circuit, relaxation oscillator, zero detector, comparator, with astable and monostable multivibrators (op-amp ). Thyristor general application introductory, AC to DC inverter DC to AC inverter, DC to DC invertor, AC to AC inverter, phase controlled half wave

Theoretical syllabusweek Half controller full wave rectifier fully controlled,resistance and inductance load generated wave forms, output voltage equation for free wheeling diode. Regenerating fully controlled inverters, examples, Dc motor speed control. Three –phase inverters, output voltage wave form with, triggering pulses and equations. Thyristor protection from the high rate change in current and voltage, protection from the transient change in source voltage, fully protection circuit from all possible faults due to current and voltage. DC to AC inverters methods of forcing the thyristor to get off. Parallel and series inverter, single and three phase, control methods in charging frequency and voltage output waveform. Inverter application, emergency power supply, single phase DC motor speed control.

Three phase motor control by using a constant ratio of variation frequency and voltage. Choppers, DC to DC inverter frequency constant, line constant. Types of choppers, DC motor speed control. AC to AC inverter, single phase voltage regulator, three phase voltage regulator. General application on single and three induction motor speed control due to the change in stator voltage, using the closed loop feed back circuit to control the slippery rings of AC motor. Cyclic inverter,AC to DC cyclic inverter, DC to DC cyclic inverter. AC to AC cyclic inverter control block diagram. Using amplitude modulation for speed control. Using polar transistor for AC motor speed control.

ألأسبوع الأول

الاختبار القبلي

Key Answer -V AK V AK I AK VBVB V BR Cut in voltage=0.7 V anod e cathod e A K + IC IB3 IB2 IB1 IB=0 VCE Cut off region Saturation Active region

Systems based on power electronics, however, suffer from the following disadvantages : Power-electronic converter circuit have a tendency to generated harmonics in the supply system as well as in the load circuit. Ac to dc and ac to ac converters operate at a low input power factor under certain operating conditions. In order to avoid a low pf, some special measures have to be adopted. Power-electronic controllers have low overload capacity. These converters must, therefore, be rated for taking momentary overloads. As such, cost of power electronic controller may increase. Regeneration of power is difficult in power electronic converter system.

command Control unit Digital circuit Power Electronic circuit Load Feedback signal Main Power source

Power electronic element

Maximum rating of power semiconductor device S.No. DeviceCircuit symbol Voltage /current rating Upper 0perating freq. (kHz) 1.Diode5000 V/5000A Thyristors (a) SCR 7000V/5000A 1.0

Upper 0perating freq. (kHz) Voltage /current rating Circuit symbol DeviceS.No V / 3000A B-LASCR V/3000 A C- GTO V / 400 A D- Triac Transistors V/400 A A-BJT

Q :- What is the structural difference between the diode and the SCR ?

A power electronic system consists of one or more power electronic converters. A power electronic converters is made up of some power semiconductor devices controlled by integrated circuit.the switching characteristics of power semiconductor devices permit a power electronic converter to shape the input power of one form to output power of some other form. Static power converters perform these functions of power conversion very efficiency.broadly speaking, power electronic converters (or circuit )can be classified into six types as under :

It is provide un controlled rectification of power and are used in applications such as electroplating, battery charging, welding, power supplies, freewheeling, and so on. It is mad in different Shapes, sizes and different rating. o choose these diodes it is important to take : - P.I.V { peak. inverse. Voltage } forward current and maximum temperature in to account.

Diode symbol and volt – ampere characteristic is show below : J1 Anod e substrate + - Drift region anode cathode A K + -V AK V AK I AK VBVB V BR Cut in voltage=0.7 V

A.C I/P Vd RLRL I VSVS t Vs ₂π₂π π VLVL

The DC component of rectifier :

The RMS component calculation:

Drive an equation to calculate the r.m.s voltage component for single phase full wave rectifier. Calculate the ripple factor and power energy conversion for full wave rectifier. For a single – phase half – wave diode rectifier feeding a resistive load R, find the values of rectifier efficiency,form factor,voltage ripple factor.in terms of Vm. Drive an equation to calculate the r.m.s voltage component for single phase full wave rectifier. Calculate the ripple factor and power energy conversion for full wave rectifier. For a single – phase half – wave diode rectifier feeding a resistive load R, find the values of rectifier efficiency,form factor,voltage ripple factor.in terms of Vm.

Key Answer

Reference الإلكترونيك الصناعي تأليف: ضياء مهدي فارس. الالكترونيك القدرة تأليف: ضياء مهدي فارس. Power electronic By Dr.P.S.Bimbhra الإلكترونيك الصناعي تأليف: ضياء مهدي فارس. الالكترونيك القدرة تأليف: ضياء مهدي فارس. Power electronic By Dr.P.S.Bimbhra