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Guru Tegh Bahadur Institute of Technology

Department of Electrical and Electronics Engineering

Semester - 7

Electric Drives - ETEE 4!

"SSIG#$E#TS

"ssignment ! %"!&

1. State some applications of electric drives.

2. What are main components of an electric drive system? Show a block diagram.3. State in brief advantages of electric drives over other drives.

4. What are functions of a power modulator in an ! system?

". State five criteria for selecting an electric drive.

#. What motor will you select to drive a light load with speed above 1$%$$$rpm?

&. 'ention four (uadrants of operation of an electric drive. )llustrate with e*ample.

+. What are different types of load re(uirements ,tor(ues-?

. Which of the following are stable operating points?

Speed /

01

0e 0l2

! 0or(ue

1$. What are types of closed loop control? !raw block diagram for a typical closed loop

speed control of an electric drive?

"ssignment '%"'&1. / single phase full converter is used to control the speed of a "hp% 11$% 12$$rpm%

separately e*cited ! motor. 0he converter is connected to a single phase 12$% #$56

supply. 0he armature resistance is $.47 and armature circuit inductance is "m5. 0he

motor voltage constant 89:$.$;rpm.

a. Rectifier operation< 0he ! motor runs at 1$$$rpm% and carries an armature

current of 3$/. /ssuming ripple free current% determine 1.=iring angle >% 2.ower

to the motor% 3.Supply power factor.

Faculty: Harshpreet Kaur

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b. Inverter Operation< 0he polarity of motor back emf is reversed% by reversing the

field e*citation. !etermine 1. =iring angle > to keep motor current at 3$/ at

1$$$rpm% and 2. 0he power fed back to the supply at 1$$$rpm.

2. / 3@ full converter is used to control the speed of a 1$$hp% #$$% 1+$$rpm% separately

e*cited ! motor. 0he converter is operated from 3@ % 4+$% #$56 supply. 0he motor

parameters are Aa:$.1 7% and a:$."m5% 89:$.3;rpm. Aated armature current is 13$/.

a. Rectifier Operation< 0he motor is running at rated conditions at 1"$$rpm.

/ssuming ripple free current% !etermine% 1.=iring angle >% and 2.Supply power

factor.

b. Inverter Operation: 0he ! machine is operated in regenerative braking mode at

1$$$rpm and rated motor current. !etermine< 1. =iring angle >% 2. 0he power fed

back to the supply% and 3. Supply power factor.

3. / separately e*cited ! motor is supplied from 23$% "$56 source% through a single

phase half controlled bridge converter. )ts field is fed through single phase semi@converter

with no firing angle delay. Aa:$.& 7% and motor constant : $."@sec;rad. =or rated load

tor(ue of 1"Bm at 1$$$rpm% and for continuous ripple free current% determine

a. =iring angle for the armature converter

b. Ams value of thyristor and freewheeling diode current

c. )nput ower factor of the armature converter

4. / separately e*cited ! motor% operating from a single phase half controlled bridge at a

speed of 14$$rpm% has an input voltage of 33$sin314t and a back '= of +$. 0he

firing angle is 3$oin every half cycle and armature resistance is $.4 7. alculate average

)aand motor tor(ue 0.

". 0he speed of a 1"hp% 22$% 1$$rpm dc series motor is controlled using a single phase half

controlled bridge converter. 0he combined armature and field resistance is $.2 7.

/ssuming a continuous and ripple free motor current and speed of 1$$$rpm and 8

:$.$3Bm;/2% determine

a. 'otor current

b. 'otor tor(ue for firing angle : 3$$. / voltage is 2"$.

#. / separately e*cited ! motor drives a load tor(ue of +"Bm at 12$$rpm. Aa:$.2 7% and

Af:2$$ 7. 0he field winding is connected to a 1@phase% 4$$ source through a single

phase full converter with firing angle : $$. 0he armature converter is also connected to

the same supply through a single phase full converter. 0he motor constant is $."@sec;/@

rad. =or ripple free armature and field currents% determine