It’s a power electronics project. It is able to give output voltage(DC) more and less than input voltage as per requirement. We can generate variable DC voltage which is less than input, but, the special things about this converter is, it has capability to produce variable DC voltage as high as twice the input voltage. We have specially designed and manufactured inductor for this project.

1. PRSENTED BY:
NAME EXAM SEAT NO.
KIRTIKUMAR PATIL W3094051
SAGAR PATIL W3094052
GOPAL PAWASKAR W3094053
GUIDED BY:
DR.D.S.MORE

2. INTRODUCTION
 Buck-boost converter operates on dc supply
 Buck operation
 Boost operation
 Duty ratio of control signal defines its
operation

3. CONTROL CIRCUIT

4. OPERATION OF CONTROL CIRCUIT
 To drive the mosfet op-amp based circuit is
designed
 Op-amp(A) is used as an integrator
 Op-amp(B) and op-amp(c) is used as a comparator
 Transistor 2N5294 is used as a switch to provide
control signal
 Frequency and duty ratio of output signal can be
controlled by using potentiometer in this circuit

5.  Output waveform of Op-amp(A)
 Output waveform of Op-amp(B)
 Output waveform of control circuit

6. POWER CIRCUIT

7. OPERATION OF POWER CIRCUIT
 Step 1: when mosfet is ON
 Voltage across inductor L is equal to V (source voltage)

8.  Step 2: when mosfet is OFF
 Voltage across inductor L is equal to Vo (in reverse
direction)
 Here output voltage developed across load is Vo

9.  Step 3: When mosfet is ON in next cycle
Load is isolated from voltage source
In this case charged capacitor across load will maitain
voltage across load

10. DUTY RATIO
 Duty ratio(D) is defined as Ton/T
here, Ton=ON time
T=time period of gate signal
 D=Ton/T
Ton=DT
T=Ton+Toff
Toff=T-Ton
Toff=(1-D)T

11. VOLTAGE ACROSS INDUCTOR
 When mosfet is ON, voltage across inductor is equal to
source voltage(V).
 When mosfet is OFF, voltage across inductor is equal to
output voltage(Vo)
 As average voltage across inductor
is zero
Hence,
V*D*T=Vo*(1-D)*T
Vo=V* D
1-D

12. Vo=V* D
1-D
 This equation shows that output voltage depends
on duty ratio(D)
 For buck operation
D=0 to 0.5
 For boost operation
D=0.5 to 1

14. APPLICATIONS
 Used in many industrial applications such as
subway cars, trolley buses, battery operated
vehicles, battery charging etc.
 To provide smooth control on output, high
efficiency, fast response and regeneration.
 To provide efficient control on dc motor operation
 To provide long life and less maintenance due to
absence of moving parts.