How can I control the speed of a brushed DC motor using PWM and PID?

Attached is the simulink model I have created for an assignment. For the assignment, we are tasked with using PWM and a control strategy (e.g. PID controller) to the maintain the speed of the DC motor at 50 RPM. The motor experiences a disturbance torque that I have listed under the Step Function Load Torque: intially its value is 20e-03 N.m and at 30 seconds, it changes to 60e-03 N.m. The voltage requirement also should not exceed 12 Volts so I used a value of 10 for a test value. My values of L, R, k, ke, J, and B are used from a quiz I had recently taken and are arbritary and can be changed. Is this a good start to solving the problem i.e did I set up the model appropriately to solve the problem? Also can someone please explain the use of the PWM generator in speed control?

Thank you for any help!

Answer 1

[Sabin]

The DC motor is usually controlled using a cascade control structure with an inner current control loop and an outer speed control loop. The inner controller will output the reference voltage used by the PWM generator. Simscape Electrical provides several examples with DC motor control. A relevant one is:

https://www.mathworks.com/help/sps/ug/dc-motor-control.html