This project demonstrates the speed control of a Brushed DC Motor using Pulse Width Modulation (PWM) in MATLAB Simulink.
PWM is one of the most widely used techniques in industrial motor drives, robotics, electric vehicles, and automation systems. By varying the duty cycle of a PWM signal, the average voltage applied to the motor changes, allowing smooth control of motor speed without significant power loss.
The simulation models the electrical and mechanical behavior of a DC motor and visualizes its speed response under PWM excitation.
- Understand PWM-based motor speed control.
- Simulate a Brushed DC Motor in Simulink.
- Observe motor transient and steady-state behavior.
- Analyze the effect of PWM duty cycle on motor speed.
- Measure shaft angular velocity using a rotational motion sensor.
Pulse Width Modulation controls the average voltage delivered to a load by rapidly switching the supply ON and OFF.
The average voltage supplied to the motor is:
Vavg = D × Vs
where:
- Vavg = Average motor voltage
- D = Duty Cycle (0 to 1)
- Vs = Supply Voltage
Motor speed is approximately proportional to the average voltage:
ω ∝ Vavg
Increasing the duty cycle increases the motor speed, while decreasing the duty cycle reduces the speed.
The model consists of:
- DC Voltage Source
- Pulse Voltage Source (PWM Generator)
- N-Channel MOSFET
- Brushed DC Motor
- Electrical Reference
- Solver Configuration
- Mechanical Rotational Reference
- Inertia Block
- Ideal Rotational Motion Sensor
- PS-Simulink Converter
- Scope
- A Pulse Voltage Source generates a PWM signal.
- The PWM signal drives the MOSFET gate.
- The MOSFET switches motor power ON and OFF.
- The motor receives a PWM-controlled average voltage.
- The rotor accelerates according to motor torque.
- Speed is measured using a rotational motion sensor.
- The measured angular velocity is displayed on a scope.
DC Supply | v Brushed DC Motor | MOSFET Switch | Ground
PWM Source | v MOSFET Gate
Motor Shaft | v Rotational Motion Sensor | PS-Simulink Converter | Scope
The motor exhibits a first-order speed response.
Observed behavior:
- Low PWM Duty Cycle → Low Final Speed
- Medium PWM Duty Cycle → Moderate Final Speed
- High PWM Duty Cycle → High Final Speed
The speed response rises rapidly and settles at a steady-state value determined by the applied duty cycle.
| Duty Cycle | Expected Speed |
|---|---|
| 10% | Low |
| 50% | Medium |
| 80% | High |
- MATLAB
- Simulink
- Simscape
- Simscape Electrical
- Electric Vehicles
- Industrial Motor Drives
- Robotics
- Conveyor Systems
- CNC Machines
- Drone Propulsion Systems
- Automated Manufacturing
- Closed-Loop PID Speed Control
- Load Torque Disturbance Analysis
- Speed vs Duty Cycle Characterization
- Current Monitoring
- Efficiency Analysis
- Real-Time Hardware Implementation using Arduino or ESP32
Smruti Ranjan Mishra
Electronics and Instrumentation Engineering
This project is provided for educational and academic purposes.