Learn How to develop Motor Control With Safety Interlock

Requirement

Hello guys welcome to MAE Learning and in this tutorial, we will learn and develop a Simulink-based motor safety control system design which follow below conditions:

  • The first condition is that the motor will start only when the Start switch is ON. Additionally, the Emergency Stop (EStop) must not be pressed.
  • The second condition is that if EStop is pressed, the motor will stop immediately. This happens even if the Start switch is ON.
  • And finally, when EStop is released and the Start switch is still ON, the motor will restart automatically.

Logic Design

Motor Safety Logic

So, as you can see here that I have used logical operators and conditional blocks in the system:

  • In the upper figure, you can see two inputs. The StartSwitch signal is given to an AND gate. It is paired with the inverted EStop signal as the second input. Together, they form the MotorOn signal.
  • If MotorOn equals true, the motor will run at 1500 RPM. Otherwise, the speed will be 0.
  • Secondly, you can see that the MotorOn_Status indicator shows the ON/OFF condition in real time. It is the output of a switch block.

Graph Explanation

Graph Analysis:

  • t = 0–2s → Start switch OFF, motor is also OFF.
  • t = 2–8s → Start switch ON, motor will run at 1500 RPM.
  • t = 8–9s → EStop is pressed, motor stops instantly.
  • t = 9–30s → EStop is released, Start is ON, then motor will start running again.

Result & Requirement Match:

So, in the above graph you can see that the result of simulation is exactly as per the requirement:

  • Motor runs only when Start is ON and EStop is not pressed.
  • Motor stops immediately when EStop is pressed.
  • Motor automatically resumes when EStop is released and Start is ON.