3. WHAT IS DC-DC CONVERTER?
A CONVERTER WHICH IS CAPABLE TO CONVERT FIXED DC VOLTAGE TO
VARIABLE DC SOURCE IS CALLED DC-DC CONVERTER.
WHERE IS IT REQUIRED?
WIDELY USED FOR TRACTION MOTOR CONTROL, IN DC ELECTRIC
VEHICLES, VOLTAGE REGULATORS
WHY IS IT REQUIRED?
• FAST DYNAMIC RESPONSE
• HIGH EFFICIENCY
• SMOOTH ACCELERATION
• REGENRATIVE BRAKING OF DC MOTORS
• ENERGY SAVING
HOW IS IT USED IS TO BE STUDIED.
4. PURPOSE OF DC-DC CONVERTER AS REGULATOR
• Either source varies, or load demand varies; the voltage at load
should remain constant and hence a converter should Regulate
voltage thus named as Regulator.
ControllerUnregulated Input Regulated Input
Sampling
Circuit
Comparator
Circuit
Reference Voltage
5. LINEAR VOLTAGE REGULATOR
ADVANTAGES
•Output ripple voltage is low
•Response is fast
•Less noise
•Low efficiency
•Large space required
•Output voltage will always be less than
input voltage
DISADVANTAGES
7. CONCEPT OF SWITCHING VOLTAGE REGULATOR
ADVANTAGES
• High efficiency
• Low heat generation
• Boost/buck/negative voltage operation possible
DISADVANTAGES
• More external parts required
• Complicated design
• Increased noise
• A switching regulator is a voltage regulator that uses a switching element to
transform the incoming power supply into a pulsed voltage, which is then smoothed
using capacitors, inductors, and other elements.
• Power is supplied from the input to the output by turning ON a switch (MOSFET) until
the desired voltage is reached.
• Once the output voltage reaches the predetermined value the switch element is
turned OFF and no input power is consumed.
• Repeating this operation at high speeds makes it possible to supply voltage efficiently
and with less heat generation.
8. TYPES OF DC-DC CONVERTER
DC-DC
CONVERTER
NON-ISOLATED
TYPE
BUCK BOOST
BUCK-
BOOST
ISOLATED
TYPE
FLYBACK FORWARD PUSH-PULL
25. FLYBACK CONVERTER MODES
During subinterval 1, while transistor Q1 conducts. The inductor
voltage vL, capacitor current iC, and dc source current ig,
are given by
vL = Vg
iC = – V/R
ig = i
With the assumption that the converter operates with small
inductor current ripple and small capacitor voltage ripple, the
magnetizing current i and output capacitor voltage v can be
approximated by their dc components, I and V, respectively.
vL = Vg
iC = – V/R
ig = I
27. FLYBACK CONVERTER MODES
During the second subinterval, the transistor is in the off-
state, and the diode conducts. The primary-side
magnetizing inductance voltage vL, the capacitor current iC,
and the dc source current ig, for this subinterval are:
vL= – v/n
iC = i/n– v/R
ig = 0
It is important to consistently define vL(t) on the same side
of the transformer for all subintervals.
Upon making the small-ripple approximation, one obtains
vL= – V/n
iC = I/n – V/R
ig = 0
36. MULTI-QUADRANT OPERATION OF DC-DC CHOPPERS
• There are 5 types of Chopper upon the direction of voltage and current.
1. Class A (1st Quadrant Operation)
2. Class B (2nd Quadrant Operation)
3. Class C (1st and 2nd Quadrant Operation)
4. Class D (1st and 4th Quadrant Operation)
5. Class E (All Quadrant Operation)
45. Applications
SMPS (Switch Mode Power Supply)
DC Motor Speed Control
DC Voltage Booster
Battery Charger
Railway Traction system
Electric Car (Vehicle)