PWM generation in Simulink

Introduction

PWM (Pulse Width Modulation) helps control power to devices by turning signals on and off quickly. Simulink lets you create and test PWM signals easily without hardware.

Controlling motor speed in a simulation before building a real controller

Testing how changing PWM duty cycle affects power delivery in circuits

Simulating LED brightness control using PWM signals

Learning how PWM signals work in electronics and control systems

Syntax

Simulink

1. Use a 'Pulse Generator' block to create a square wave.
2. Set the pulse width to control the duty cycle.
3. Connect the output to your system or scope to observe the PWM signal.

The 'Pulse Generator' block frequency controls how fast the PWM switches.

The pulse width percentage sets how long the signal stays ON in each cycle.

Examples

This example sets a PWM signal that is ON half the time and OFF half the time at 1 kHz frequency.

Simulink

% Create a PWM signal with 50% duty cycle at 1 kHz
pulseWidth = 50; % percent
frequency = 1000; % Hz
% In Simulink, set Pulse Generator block parameters:
% Amplitude: 1
% Period: 1/frequency = 0.001 seconds
% Pulse Width: pulseWidth = 50

This PWM signal stays ON for 25% of each cycle, useful for lower power output.

Simulink

% Create a PWM signal with 25% duty cycle at 500 Hz
pulseWidth = 25; % percent
frequency = 500; % Hz
% Set Pulse Generator block parameters accordingly.

Sample Program

This code opens a Simulink model named 'pwm_example' that contains a Pulse Generator block configured for PWM. Running the simulation displays the PWM signal on a Scope.

Simulink

% Open Simulink model
model = 'pwm_example';
open_system(model);

% In the model, a Pulse Generator block is set with:
% Amplitude = 1
% Period = 0.002 (500 Hz)
% Pulse Width = 50 (50%)

% Run the simulation
sim(model);

% The Scope block connected to Pulse Generator shows the PWM waveform.

Important Notes

You can adjust the pulse width dynamically using other blocks to simulate changing PWM duty cycles.

Use the Scope block to visually check the PWM waveform shape and timing.

Summary

PWM signals switch ON and OFF quickly to control power.

Simulink's Pulse Generator block creates PWM by setting pulse width and frequency.

Use simulation to test PWM effects before hardware implementation.