The document describes simulating a buck converter circuit using MATLAB/Simulink. The buck converter is designed to step down an input voltage of 24V to an output voltage of 12V at a power of 100W with a switching frequency of 100kHz and within specified current and voltage ripple limits. The simulation model is developed and key waveforms are analyzed including the voltage across switches and diodes, inductor current, and output voltage. The simulated results match the theoretical calculations and design specifications.

1. EXPERIMENT NO.1 : SIMULATION OF BUCK CONVERTER USING
MATLAB / SIMULINK
Objective: Design a Buck Converter with appropriate value of parameters and simulate it.
Parameters of the Buck Converter: Input voltage: 24V; Output Voltage: 12V; Output
Power: 100W; Switching Frequency: 100kHz; Ripple in Inductor Current: 25%; Ripple in
Output Voltage: 0.1%;
Theory: Buck Converter is a DC to DC converter (Step down Chopper) having output
voltage is less than input voltage i.e. Vo< Vin
Duty Ratio
D = =
Circuit Diagram and Theoratical Waveforms:

2. Design procedure and final design parameters obtained:
1. Duty Ratio:
D =
So, D=0.5
2. Ripple in Inductor Current:
ΔIL (Theoretical) = 2.08Amp.
ΔIL =
So, L = 28.85µH
where f is switching frequency

3. 3. Ripple in Output Voltage:
ΔVo (Theoretical) = 0.012V
ΔVo =
So, C = 217µF
4. Avg Current through Inductor (Theoretical):
IDC =
IDC = 8.33Amp.
5. Load Resistance:
RL (Fixed) = = 1.44Ω
Results:
1. Simulation Model of Buck Converter:
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.

4. 2. Source Voltage Waveform:
Vin = 24V
Time (sec.)
3. Switching signal to turn ON/OFF to MOSFET:
4. Voltage Across the Diode:
When Diode is OFF
VD = 24 V
When Diode is ON
VD = -0.8V

5. 5. Voltage across the Switch/MOSFET:
When MOSFET/switch is ON
VSW = 0.8V
When MOSFET/switch is OFF
VSW = 24V

6. 6. Current through Inductor:
Avg Current through Inductor (Practical)
IDC = 7.9Amp.
Ripple in Inductor Current (Practical)
ΔIL = 2Amp.
7. Output voltage:
Output Avg. Voltage (Practical)
Vo=11.43V
Ripple in Output Voltage (Practical)
ΔVo = 0.011V