Motor startup and braking simulation in Simulink - Step-by-Step Execution

Concept Flow - Motor startup and braking simulation

Start Simulation

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Apply Voltage to Motor

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Motor Accelerates

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Check Speed Threshold

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Apply Braking

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Motor Decelerates

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Motor Stops

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End Simulation

The simulation starts by applying voltage to the motor, causing it to accelerate. When a speed threshold is reached, braking is applied to decelerate the motor until it stops, ending the simulation.

Execution Sample

Simulink

1. Apply voltage input to motor block
2. Motor speed increases over time
3. When speed > threshold, apply braking torque
4. Motor speed decreases until zero
5. Stop simulation

This code simulates motor startup by increasing speed, then braking to stop the motor.

Execution Table

Step	Motor Speed (rpm)	Voltage Applied (V)	Braking Torque (Nm)	Condition	Action
1	0	24	0	Speed < Threshold (1000 rpm)	Apply voltage, motor accelerates
2	400	24	0	Speed < Threshold	Continue acceleration
3	800	24	0	Speed < Threshold	Continue acceleration
4	1000	24	0	Speed = Threshold	Prepare to brake next step
5	1000	0	5	Speed >= Threshold	Apply braking torque, voltage off
6	700	0	5	Speed > 0	Motor decelerates
7	300	0	5	Speed > 0	Motor decelerates
8	0	0	0	Speed = 0	Motor stopped, end simulation

💡 Motor speed reaches zero, simulation ends

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6	After Step 7	Final
Motor Speed (rpm)	0	400	800	1000	1000	700	300	0	0
Voltage Applied (V)	24	24	24	24	0	0	0	0	0
Braking Torque (Nm)	0	0	0	0	5	5	5	0	0

Key Moments - 3 Insights

Why does the voltage drop to zero when braking starts?

Voltage is turned off at step 5 to stop accelerating the motor, allowing braking torque to slow it down, as shown in execution_table row 5.

Why is braking torque zero at the start and end?

Braking torque is zero initially because the motor is accelerating, and zero at the end because the motor has stopped, as seen in execution_table rows 1 and 8.

How do we know when to switch from acceleration to braking?

The condition 'Speed >= Threshold' at step 5 triggers braking, shown in execution_table row 4 and 5.

Visual Quiz - 3 Questions

Look at the execution table, what is the motor speed at step 3?

A 800 rpm

B 1000 rpm

C 400 rpm

D 0 rpm

💡 Hint

Check the 'Motor Speed (rpm)' column at step 3 in the execution_table.

At which step does the voltage applied drop to zero?

A Step 4

B Step 5

C Step 6

D Step 7

💡 Hint

Look at the 'Voltage Applied (V)' column in the execution_table to find when it changes from 24 to 0.

If braking torque was applied earlier at step 3, what would happen to motor speed at step 4?

A Motor speed would be higher than 1000 rpm

B Motor speed would stay at 1000 rpm

C Motor speed would be about 800 rpm or less

D Motor speed would instantly drop to zero

💡 Hint

Refer to the variable_tracker showing how braking torque slows motor speed over steps.

Concept Snapshot

Motor startup and braking simulation:
- Apply voltage to accelerate motor
- Monitor speed until threshold reached
- Turn off voltage and apply braking torque
- Motor decelerates until stop
- Simulation ends when speed is zero

Full Transcript

This simulation models a motor starting up by applying voltage, causing it to speed up. When the motor reaches a set speed threshold, the voltage is turned off and braking torque is applied to slow it down. The motor speed decreases step by step until it stops, ending the simulation. The execution table shows each step's motor speed, voltage, braking torque, and actions taken. Variables change over time, with speed increasing during acceleration and decreasing during braking. Key moments clarify why voltage drops when braking starts and how braking torque affects speed. The visual quiz tests understanding of these steps and variable changes.