Download **** 1

1
Boost converter design
2014. 12. 14.
Circuit theory I
EMLAB
Introduction
2
• One of the most common and necessary sub-circuits that appears in a wide
variety of electronic systems—for example, stereos, TVs, radios, and
computers—is a quality DC voltage source or power supply.
• Although levels of alternating current (AC) voltages can be changed simply
by transformers, conversions of dc voltages to lower or higher levels can not
be accomplished by simple means.
• Conversion to lower voltage levels may be simply done by connecting a series
resistor, which entails power consumption. Conversion to higher levels cannot
be done using resistors.
• DC-DC converters are invented to accomplish voltage conversion to
higher/lower levels without unnecessary power consumption. They utilize
switches to change the voltage levels.
• In this design project, a DC-DC converter topology called the boost converter
is considered which changes the voltage to higher level.
EMLAB
Basic topology
3
By changing the states of switches S1 and S2 of those of figure (a) or figure (b)
periodically, higher voltage levels can be accomplished.
Exemplary output
voltage
Vo (t )
EMLAB
4
Specification
•
•
•
•
•
•
The switching speed is lower than 100 kHz.
The average output voltage should become 20V.
The ripples contained in the output voltage should be less than 10 mV
The load resistance is 100 Ω.
The value of inductance L should be less than 1 mH to minimize the size.
The rise time of the output voltage should be less than 0.5 s.
R  100 []
Vin  5 [V ]
10 mV
Rising time (tr) is
the time required
for the response to
rise from 10% to
90% of its final
value
tr  0.5 [ s ]
EMLAB
Report
5
Reports on this design project should include the followings :
1. A schematic circuit that satisfies the specification.
2. PSpice simulation results that show the meets the design specification.
3. Detailed explanations on how the values of circuit elements are derived.
EMLAB
Exemplary circuit
6
EMLAB