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

13.
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.