Buck-Boost Converter
- 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
- 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
- 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.