The document describes simulating a buck/boost converter using MATLAB/Simulink. It provides parameters for an input voltage of 24V, output voltage of 48V at 100W. It then outlines the theory, design procedure, and parameters calculated for an inductor value of 102.5μH and capacitor value of 288.6μF. The simulation model is shown and results presented including waveforms for the input voltage, switch signal, voltages across components, inductor current, and output voltage.

1. EXPERIMENT NO. 3 : SIMULATION OF BUCK / BOOST
CONVERTER USING MATLAB / SIMULINK
Objective: Design a Buck / Boost Converter with appropriate value of parameters and
simulate it.
Parameters of the Buck / Boost Converter:
Input voltage: 24V
Output Voltage: 48V
Output Power: 100W
Switching Frequency: 100kHz
Ripple in Inductor Current: 25%
Ripple in Output Voltage: 0.1%
Theory: Buck/Boost Converter is a DC to DC converter (Step up/down Chopper), By
adjusting Duty Ratio we can use either as Buck Converter (Vo < Vin) or Boost Converter (Vo
> Vin)
Duty Ratio
D = =
Circuit Diagram and Theoratical Waveforms:

2. Design procedure and final design parameters obtained:
For getting desired response (VO = 48V) first we will design L & C by using
given parameters. By using L & C we will design a Buck/Boost Converter and
simulate it.
1. Duty Ratio:
D =
So, D=0.666

3. 2. Avg Current through Inductor (Theoretical):
IL = IS + IO = +
IL = 6.25 Amp.
3. Ripple in Inductor Current:
ΔIL (Theoretical) = 1.5625 Amp.
ΔIL =
So, L = 102.5µH
where f is switching frequency
4. Ripple in Output Voltage:
ΔVo (Theoretical) = 0.048V
ΔVo =
So, C = 288.6µF
5. Load Resistance:
RL (Fixed) = = 23.04Ω

4. 6. Simulation configuration parameters:
Here we are taking 100 Samples for each Time period So, Sampling frequency is
100 times of switching frequency(100kHz).
So, Sampling Time Period = 100nSec.
7. Simulation Model of Buck Converter:

5. Results:
1. Source Voltage Waveform:
Vin = 24V
2. Switching signal for turn ON/OFF to MOSFET:
3. Voltage Across the Diode:
When Diode is OFF
VD = 72 V
When Diode is ON
VD = -0.8V

6. 4. Voltage across the Switch/MOSFET:
When MOSFET/switch is ON
VSW = 0.8V
When MOSFET/switch is OFF
VSW = 72V
5. Current through Inductor:
Avg Current through Inductor (Practical)
IS = IL = 6.25Amp.
Ripple in Inductor Current (Practical)
ΔIL = 1.5Amp.

7. 6. Output voltage:
Output Avg. Voltage (Practical)
Vo= 46.37V
Ripple in Output Voltage (Practical)
ΔVo = 0.041V