functions of dc-dc converters and types

1. ANALYSIS, DESIGN AND MODELING
OF DC-DC CONVERTER USING
SIMULINK
PROJECT GUIDE : PRESENTED BY:
MR. J YADAGIRI R.SRIKANTH -187Q5A0249
ASST. PROF., N.UDAYKUMAR-187Q5A0242
I.DEEPIKA -187Q5A0221
G.VINAY -187Q5A0219

2. ABSTRACT
1. DC-DC converters are widely used to efficiently produce a regulated voltage from a source that may or may not
be well controlled to a load that may or may not be constant. This ppt briefly introduces DC-DC converters,
notes common examples, and discusses important datasheet parameters and applications of DC-DC converters.
2. DC-DC converters are high-frequency power conversion circuits that use high-frequency switching and inductors,
transformers, and capacitors to smooth out switching noise into regulated DC voltages. Closed feedback loops
maintain constant voltage output even when changing input voltages and output currents. At 90% efficiency,
they are generally much more efficient and smaller than linear regulators. Their disadvantages are noise and
complexity.
3. DC-DC converters come in non-isolated and isolated varieties. Isolation is determined by whether or not the
input ground is connected to the output ground.
4. Four common topologies that makers might find useful are the buck, boost, buck-boost converters,sepic
converters
5. Simulation results for buck, boost and buck-boost converters are shown with the chance of
different input parameters

3. INTRODUCTION TO DC-DC
CONVERTERS

5. DC –DC CONVERTER TYPES
1. Step-down(buck):A buck converter steps a voltage down, producing a
voltage lower than the input voltage. A buck converter could be used to
charge a lithium ion battery to 4.2 V, from a 5 V USB source.
2. Step-up(boost): A boost converter steps a voltage up, producing a
voltage higher than the input voltage. A boost converter is a DC/DC switch
mode power supply that is intended to boost (or increase) the input voltage of
an unregulated DC supply to a stabilized higher output voltage.
3. Buck-Boost Converter: A buck-boost boost converter can supply a
regulated DC output from a power source delivering a voltage either
below or above the regulated output voltage.

7. What is a Buck Converter?
A buck or step-down converter is a DC/DC switch mode power supply that is intended to buck (or lower) the input
voltage of an unregulated DC supply to a stabilized lower output voltage. Buck converters are, especially
compared to traditional voltage regulators, widely valued for their extremely high efficiencies which can easily
exceed 95%. The below simplified circuit diagram shows how current flows through the circuit during a switching
event of a buck converter.
Buck converters are often used in lieu of traditional, non-efficient linear regulators to provide low-voltage on-
board power in a variety of applications such as microprocessors, communication equipment, control systems,
and more.

8. Steady-state inductor voltage and current waveform, buck converter

9. What is a Boost Converter?
A boost converter is a DC/DC switch mode power supply that is intended to boost (or increase) the input voltage of
an unregulated DC supply to a stabilized higher output voltage. Similar to a buck converter, a boost converter relies
on an inductor, diode, capacitor, and power switch regulate the output voltage, but they are arranged differently. The
below simplified circuit diagram shows how current flows through the circuit during a switching event of a boost
converter.
In a boost converter, the output voltage is varied by the mark-space ratio of the PWM signal to be equal to or
above V in. As power is conserved, a boost converter that supplies triple the input voltage will be only be able
to supply one third the current that it draws from the supply. However, boost converters are very popular in
battery powered devices, where perhaps a pair of batteries deliver 3V but need to supply a 5V circuit.

10. Steady-state inductor voltage and current waveform, boost converter

11. What is a Buck-Boost Converter?
A buck-boost boost converter can supply a regulated DC
output from a power source delivering a voltage either
below or above the regulated output voltage. A buck-boost
converter circuit combines elements of both a buck
converter and a boost converter, however they are often
larger in footprint than either alternative. The below
simplified circuit diagram shows a typical flow of current
during a switching event through a buck-boost converter.
As you may have noticed in the circuit diagram, V out is actually negative with respect to the supply potential,
which can complicate certain designs. Buck-boost converters also require more expensive components as they
need to withstand both high Vin max voltage and high input current at Vin min, but they are useful in many
applications. A very common use of buck-boost converters are for high power LED lighting where, for example,
lead-acid batteries supply a nominal 9-14V to a constant 12V LED load.

12. Advantages of DC-DC Converter
• Battery space can be reduced by reducing or increasing the available input voltage.
• A device can be driven by bucking or boosting the available voltage. Thus preventing the damage
of the device or breakdown.
• It provides technique to extend potential from partly reduced cell potential.
• It is available as whole hybrid circuit element and requires very few additional components.
• DC to DC choppers are used to regulate the voltage.
• It is constructed to make best usage of the energy yield for photo-voltaic systems.
• Isolated DC-DC converter has more energy transformer on condition of the barrier.
• The output of isolated converter is organized as positive or negative.

13. Disadvantages of DC-DC converter
Following are the drawbacks or disadvantages of DC-DC converter:
• Switching converters are prone to noise.
• They are expensive.
• Choppers are inadequate due to unsteady voltage and current supply.
• Disadvantages of fly-back type: More EMI due to gap, More ripple

14. DC-DC Converter Model

15. SIMULINK MODEL OF BUCK-BOOST
CONVERTER
controller

16. Conclusion
• The technology of buck, boost, and buck-boost converters are utilized around
the world to provide regulated low-voltage DC/DC power in nearly every
electronics market.buck, boost, and buck-boost converters are an excellent
solution for your low-power conversion needs.
• DC-DC converters and their design remain an interesting topic and new
control schemes to achieve better regulation and fast transient response are
continually developed. Step down switching regulators are the backbone of
electronic equipmentsthat employ IC’s running at supply voltages lower than
5V. A key challenge to design switching regulators is to maintain almost
constant output voltage within acceptable regulation

17. THANK YOU