FINAL REPORT
BOOST CONVERTER MODULE :
MICROCONTROLLER PWM
Group
Members:
1.
Abdillah Aziz
Munthasir (1310161018)
2.
Mohammad Agung Dirmawan (1310161024)
3.
Gilang Andaru
Trinanda (1310161027)
Class
:
3-D4
ELIN A
Lecture
:
Ir.
Moh. Zaenal Effendi, M.T.
INDUSTRIAL ELECTRICAL ENGINEERING
ELECTRO DEPARTEMENT
ELECTRONICS ENGINEERING POLYTECHNIC
INSTITUTE OF SURABAYA
2019
Introduction
A boost converter (step-up converter) is a
DC-to-DC power converter that steps up voltage (while stepping down current)
from its input (supply) to its output (load). It is a class of switched-mode
power supply (SMPS) containing at least two semiconductors (a diode and a
transistor) and at least one energy storage element: a capacitor, inductor, or
the two in combination. To reduce voltage ripple, filters made of capacitors
(sometimes in combination with inductors) are normally added to such a
converter's output (load-side filter) and input (supply-side filter).
Figure
1.1. Boost Converter Schematic
Operation
The key principle that drives the boost converter is the
tendency of an inductor to resist changes in current by creating and destroying
a magnetic field. In a boost converter, the output voltage is always higher
than the input voltage. A schematic of a boost power stage is shown in Figure
1.
a.
When the switch is closed,
current flows through the inductor in clockwise direction and the inductor
stores some energy by generating a magnetic field. Polarity of the left side of
the inductor is positive.
b.
When the switch is opened,
current will be reduced as the impedance is higher. The magnetic field
previously created will be destroyed to maintain the current towards the load.
Thus the polarity will be reversed (meaning the left side of the inductor will
become negative). As a result, two sources will be in series causing a higher
voltage to charge the capacitor through the diode D.
If the switch is cycled fast enough, the inductor will not discharge fully in between charging stages, and the load will always see a voltage greater than that of the input source alone when the switch is opened. Also while the switch is opened, the capacitor in parallel with the load is charged to this combined voltage. When the switch is then closed and the right hand side is shorted out from the left hand side, the capacitor is therefore able to provide the voltage and energy to the load. During this time, the blocking diode prevents the capacitor from discharging through the switch. The switch must of course be opened again fast enough to prevent the capacitor from discharging too much.
Figure 1.2 The two current paths of a boost converter, depending
on the state of the switch S.
The basic principle of a Boost converter consists of 2 distinct
states (see figure 2):
- in the On-state, the switch S (see figure 1) is
closed, resulting in an increase in the inductor current;
- in the Off-state, the switch is open and the only
path offered to inductor current is through the flyback diode D, the
capacitor C and the load R. This results in transferring the energy
accumulated during the On-state into the capacitor.
- The input current is the same as the inductor
current as can be seen in figure 2. So it is not discontinuous as in the
buck converter and the requirements on the input filter are relaxed
compared to a buck converter.
·
When switch S is ON
When switch in ON the diode will be open circuited since
the n side of diode is at higher voltage compared to p side which is shorted to
ground through the switch. Hence the boost converter can be redrawn as follows.During this state the
inductor charges and the inductor current increases. The current through the
inductor is given as
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