Sinusoidal PWM (SPWM) technique in Power Electronics - Mini Project: Build & Apply

Understanding Sinusoidal PWM (SPWM) Technique

📖 Scenario: You are working on a project to control the speed of an AC motor using an inverter. To do this efficiently, you need to understand how Sinusoidal Pulse Width Modulation (SPWM) works, which is a common technique used in inverters to create a smooth AC output from a DC source.

🎯 Goal: Build a step-by-step conceptual understanding of the Sinusoidal PWM (SPWM) technique by creating a simple representation of the SPWM waveform generation process.

📋 What You'll Learn

Create a sine wave reference data set representing the desired AC output.

Define a carrier wave threshold for comparison.

Implement the SPWM logic by comparing the sine wave with the carrier wave to generate PWM signals.

Complete the representation by indicating the PWM output states.

💡 Why This Matters

🌍 Real World

SPWM is widely used in power electronics to control AC motor speed and inverter output voltage smoothly and efficiently.

💼 Career

Understanding SPWM is essential for engineers working with motor drives, renewable energy inverters, and power converters.

1

Create the sine wave reference data

Create a list called sine_wave with these exact 5 values representing one cycle of a sine wave: 0.0, 0.5, 1.0, 0.5, 0.0.

Power Electronics

# Create the sine_wave list with the specified values
# Your code here

Need a hint?

Think of the sine wave as a list of amplitude points sampled over one cycle.

2

Define the carrier wave threshold

Create a variable called carrier_threshold and set it to 0.6 to represent the carrier wave level used for PWM comparison.

Power Electronics

sine_wave = [0.0, 0.5, 1.0, 0.5, 0.0]
# Define the carrier_threshold variable
# Your code here

Need a hint?

The carrier threshold is a fixed value to compare against sine wave points.

3

Generate the PWM signal by comparison

Create a list called pwm_signal that contains 1 if the corresponding sine_wave value is greater than carrier_threshold, otherwise 0. Use a for loop with variable value to iterate over sine_wave.

Power Electronics

sine_wave = [0.0, 0.5, 1.0, 0.5, 0.0]
carrier_threshold = 0.6
# Create pwm_signal list using a for loop and comparison
# Your code here

Need a hint?

Compare each sine wave point to the carrier threshold and append 1 or 0 accordingly.

4

Complete the SPWM representation

Add a comment line that explains the pwm_signal list represents the SPWM output where 1 means the switch is ON and 0 means the switch is OFF.

Power Electronics

sine_wave = [0.0, 0.5, 1.0, 0.5, 0.0]
carrier_threshold = 0.6
pwm_signal = []
for value in sine_wave:
    if value > carrier_threshold:
        pwm_signal.append(1)
    else:
        pwm_signal.append(0)
# Add a comment explaining the pwm_signal meaning
# Your code here

Need a hint?

Explain clearly what the PWM signal values mean in the context of switching.