Torque and speed control loop in EV Technology - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the main purpose of the torque control loop.

EV Technology

The torque control loop primarily aims to [1] the motor torque accurately.

Drag options to blanks, or click blank then click option'

Ameasure

Bincrease

Cignore

Dregulate

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing regulation with measurement.

Assuming the loop increases torque without control.

The torque control loop is designed to regulate the motor torque to match the desired value precisely.

2fill in blank

medium

Complete the code to describe the role of the speed control loop.

EV Technology

The speed control loop adjusts the [1] to maintain the desired motor speed.

Drag options to blanks, or click blank then click option'

Acurrent

Bvoltage

Ctorque

Dtemperature

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing voltage or current instead of torque.

Thinking temperature controls speed.

The speed control loop changes the torque to keep the motor speed at the setpoint.

3fill in blank

hard

Fix the error in the statement about feedback signals in the control loops.

EV Technology

The torque control loop uses [1] feedback, while the speed control loop uses speed feedback.

Drag options to blanks, or click blank then click option'

Atorque

Bvoltage

Cspeed

Dtemperature

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up torque and speed feedback signals.

Assuming voltage or temperature feedback is used.

The torque control loop uses torque feedback to adjust the motor torque accurately.

4fill in blank

hard

Fill both blanks to complete the description of the control loops' hierarchy.

EV Technology

The [1] control loop sets the reference for the [2] control loop.

Drag options to blanks, or click blank then click option'

Aspeed

Btemperature

Ctorque

Dvoltage

Attempts:

3 left

💡 Hint

Common Mistakes

Reversing the hierarchy of loops.

Choosing unrelated parameters like temperature or voltage.

The speed control loop sets the torque reference, which the torque control loop then regulates.

5fill in blank

hard

Fill all three blanks to complete the formula for torque control in the loop.

EV Technology

Torque command = Kp * ([1] - [2]) + Ki * ∫([3] - [2]) dt

Drag options to blanks, or click blank then click option'

Atorque reference

Bmeasured torque

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up reference and measured torque in the formula.

Using different variables for proportional and integral parts.

The torque control uses the difference between torque reference and measured torque for proportional and integral control.

Practice

1. What is the main role of the speed control loop in an electric vehicle motor system?

easy

A. To decide how much torque is needed based on speed error

B. To convert torque commands into motor current

C. To measure the battery voltage

D. To control the temperature of the motor

Solution

1. Step 1: Understand the speed control loop function

   The speed control loop compares the desired speed with the actual speed and calculates the difference called speed error.

2. Step 2: Determine the output of the speed control loop

   Based on the speed error, it decides the amount of torque needed to correct the speed.

3. Final Answer:

   To decide how much torque is needed based on speed error -> Option A

4. Quick Check:

   Speed control loop = torque decision [OK]

Hint: Speed loop sets torque based on speed difference [OK]

Common Mistakes:

• Confusing torque control with speed control
• Thinking speed loop measures battery voltage
• Assuming speed loop controls motor temperature

2. Which of the following correctly describes the torque control loop in an EV motor system?

easy

A. It converts torque commands into motor current

B. It measures the motor speed directly

C. It calculates speed error from desired and actual speed

D. It controls the battery charging rate

Solution

1. Step 1: Identify the function of the torque control loop

   The torque control loop takes the torque command from the speed control loop and converts it into the motor current needed to produce that torque.

2. Step 2: Eliminate incorrect options

   Measuring speed and calculating speed error are functions of the speed control loop, not torque control. Battery charging is unrelated.

3. Final Answer:

   It converts torque commands into motor current -> Option A

4. Quick Check:

   Torque loop = torque to current conversion [OK]

Hint: Torque loop changes torque command into current [OK]

Common Mistakes:

• Mixing speed error calculation with torque control
• Thinking torque loop measures speed
• Confusing battery charging with torque control

3. Consider this simplified control sequence:
speed_error = desired_speed - actual_speed
torque_command = Kp * speed_error
motor_current = torque_command * motor_constant
If desired_speed = 100, actual_speed = 80, Kp = 2, and motor_constant = 3, what is the motor_current?

medium

A. 40

B. 60

C. 360

D. 120

Solution

1. Step 1: Calculate speed error

   speed_error = 100 - 80 = 20

2. Step 2: Calculate torque command

   torque_command = 2 * 20 = 40

3. Step 3: Calculate motor current

   motor_current = 40 * 3 = 120

4. Final Answer:

   120 -> Option D

5. Quick Check:

   speed_error * Kp * motor_constant = 120 [OK]

Hint: Multiply error by Kp, then by motor constant [OK]

Common Mistakes:

• Multiplying in wrong order
• Using actual_speed instead of speed_error
• Forgetting to multiply by motor_constant

4. A control loop code snippet is:
speed_error = desired_speed - actual_speed
torque_command = Kp * speed_error
motor_current = torque_command / motor_constant
Why might this cause a problem in the torque control loop?

medium

A. Multiplying torque_command by Kp is wrong

B. Dividing by motor_constant reduces current incorrectly

C. Speed error should be added, not subtracted

D. motor_current should be zero always

Solution

1. Step 1: Analyze the motor_current calculation

   The torque control loop converts torque command to motor current by multiplying by motor_constant, not dividing.

2. Step 2: Understand the effect of division

   Dividing by motor_constant reduces the motor_current incorrectly, leading to insufficient torque output.

3. Final Answer:

   Dividing by motor_constant reduces current incorrectly -> Option B

4. Quick Check:

   Torque to current = multiply, not divide [OK]

Hint: Torque to current uses multiplication, not division [OK]

Common Mistakes:

• Confusing multiplication with division
• Misunderstanding speed error calculation
• Assuming motor_current should be zero

5. In an EV torque and speed control system, if the speed control loop outputs a negative torque command, what should the torque control loop do to maintain correct motor operation?

hard

A. Convert the negative torque command into a positive motor current to increase speed

B. Ignore the negative torque command and set motor current to zero

C. Convert the negative torque command into a negative motor current to reverse motor direction

D. Send an error signal and stop the motor immediately

Solution

1. Step 1: Understand negative torque command meaning

   A negative torque command means the motor should apply torque in the opposite direction, usually to slow down or reverse.

2. Step 2: Determine torque control loop response

   The torque control loop must convert this negative torque command into a negative motor current, which causes the motor to rotate in reverse or apply braking torque.

3. Final Answer:

   Convert the negative torque command into a negative motor current to reverse motor direction -> Option C

4. Quick Check:

   Negative torque = negative current for reverse [OK]

Hint: Negative torque means reverse current direction [OK]

Common Mistakes:

• Ignoring negative torque commands
• Converting negative torque to positive current
• Stopping motor unnecessarily on negative torque