1. DC DRIVES WITH DC-
DC CONVERTER
PREPARED BY:- kaushal
boghani
(130760109002)
SUBMITED TO:-Prof. Archan
Patel.
Prof. Richa
Mali.
SHREE SWAMI ATMANAND SARASWATI
INSTITUTE OF TECHNOLOGY.
3. ABSTRACT:-
•Here we are going to study about the design of dc drive with use of dc – dc converter
or dc chopper .design of choke coil 1-phase and 3-phase variable choke coil.
•We will also cover the topic like how duty cycle is affected to speed of motor and
armature voltage .
•We are going to study about the different mode of operation like motoring mode
regenerating mode in different quadrant with circuit diagram.
•equation of power , armature voltage , armature current and speed in terms of duty
cycle .
•Waveforms of different quantities .
•We are going to see the application of different mode of operation of dc motor by
use of dc drive with dc chopper .
4. INTRODUCTION
•The dc to dc converter or chopper based dc motor drives are widely used in traction
application.
•By varying duty cycle we can control the speed of dc motor and armature voltage.
•Chopper provides the regenerative braking which returns energy to source and
improves efficiency.
•Chopper drives can operate in one , two, or four quadrant.
5. MODE OF OPERATION
1. Principle of Power Control
2. Principle of Regenerative Brake Control
3. Principle of Rheostatic Brake Control
4. Combined Regenerative and Rheostatic Brake Control
5. Two and Four Quadrant DC – DC Converter Drives
8. POWER CONTROL OR
MOTORING CONTROL
•As shown in fig basic arrangement of dc chopper feeding power to dc series
motor.
•it consist of force commutated thyristor.it could equally well be transistor switch.
• Assumed armature current is continuous and ripple free.
The average armature voltage is
sona
onsa
sa
VfTV
TTVV
kVV
/
9. The power supplied to the motor is
The average value of the input current is
Input power to chopper= (average i/p voltage)(average source current)
For motor armature circuit,
asaao IkVIVP
as kIV .
.
.
.
/)]([
)(.
.
)(.
msaatm
saammt
mma
saaast
KRRIV
RRIKV
KE
RRIEkVV
akI
10. REGENERATIVE BRAKING
CONTROL
•In regenerative braking control motor act as generator and kinetic energy of motor is
connected to load is returned to source.
•During motoring mode supply voltage is larger than back emf but in case of
regenerating mode back emf is greater than supply voltage
•During chopper is on and it act as short circuited and becomes zero. during
• period F.D conduct and becomes high & current flows into the supply
onT tV
offT tV
11.
12. •The average voltage across the transistor is
•The regenerated power can be found from
•The voltage generated by the motor acting as a generator is
TTVV offsch /
)1( kVIP sag
amsamchg
mmg
IRVkIRVE
KE
)1(
dTdILIRE aamg /.)(
0)(
0/
amg
a
IRE
dTdI
13. •During chopper on
•Hence,
•During chopper off
•Hence,
•Regenerative braking in separately excited dc motor is stable but in case of dc series
motor it is difficult.
samg VIRE )(0
0tV
0)( amg IRE
m
am
K
IR
min
st VV
samg VIRE )(
m
am
m
s
K
IR
K
V
max
m
am
m
s
m
m
am
K
IR
K
V
K
IR
14. RHEOSTAT BAKING CONTROL
•In dynamic braking energy stored
by motor is dissipated in rheostat
•Dynamic braking used in local
trains to heat the engine.
16. PRINCIPLE OF RHEOSTATIC BRAKE
CONTROL
•The average current in the braking resistor is
•The average voltage across the braking resistor is
•The equivalent load resistance of the generator
•The power dissipated in the resistor Rb is
)1( kII ab
)1( kIRV abb
mb
a
b
eq RkR
I
V
R )1(
)1(2
kRIP bab
18. •Used when the supply is partly “receptive”
•Remove regenerative braking if line
voltage is too high
•Turn thyristor TR on
•Divert current to RB
•Apply rheostatic braking
•TR is “self-commutated”
19. TWO-QUADRANT DC–DC
CONVERTER DRIVE
•Motoring control for chopper drive provide only first quadrant drive because
armature voltage and current remain positive.
•In regenerative braking control for chopper drive provide only second quadrant drive
because armature voltage remain positive and current remain negative .
•In two quadrant chopper drive ,both motoring mode and regenerative braking mode
Are carried out by one chopper configuration.
22. POWER CONTROL MODE
•Q1 and D2 operate
•Q1 ON, Vs applied to the motor
•Q1 turned OFF, D2 “free-wheels”
•Armature current decays
23. REGENERATIVE CONTROL MODE
•Q2 and D1 operate
•Q2 turned ON, motor acts as a generator,
and the armature current rises
•Q2 turned OFF, motor returns energy to
the supply via D1 “free-wheeling”
24. FOUR-QUADRANT DC–DC
CONVERTER DRIVE
•In four quadrant dc chopper drive motor can work in below mode.
1. Forward motoring mode
2. Forward regenerative mode
3. Reverse motoring mode
4. Reverse regenerative mode
27. FORWARD POWER CONTROL MODE
•Q1 and Q2 turned ON
•Supply voltage appears across the motor
•Armature current rises
•Q1 and Q2 turned OFF
•Armature current decays via D3 and D4
28. FORWARD REGENERATION MODE
•Q1, Q2, and Q3 turned OFF
•Turn Q4 ON
•Armature current rises and flows through Q4,
D2
•Q4 turned OFF, motor acts as a generator,
returns energy back to the supply via D1, D2
ia reverses
29. REVERSE POWER CONTROL MODE
•Q3 and Q4 turned ON
•Supply voltage appears in the reverse
direction across the motor
•Armature current rises and flows in the
reverse direction
•Q3 and Q4 turned OFF
•Armature current decays via D1 and D2
ia
30. REVERSE REGENERATION MODE
•Q1, Q3, Q4 turned OFF
•Q2 turned ON
•Armature current rises through Q2 and D4
•Q2 turned OFF
•Armature current falls and returns energy via
D3 and D4
i a
