H-bridge driver simulation in Simulink - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the input voltage source block.

Simulink

voltage_source = Simulink.VoltSource([1]);

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

A5

B10

C12

D15

Attempts:

3 left

💡 Hint

Common Mistakes

Using too high or too low voltage values that are not typical for H-bridge simulation.

The input voltage source is set to 10 volts to simulate a typical H-bridge supply.

2fill in blank

medium

Complete the code to set the PWM frequency for the H-bridge driver.

Simulink

pwm_frequency = [1];  % in Hz

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

A5000

B2000

C1000

D10000

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing too low frequency causing motor noise or too high causing switching losses.

The PWM frequency is set to 5000 Hz, which is common for motor control to balance efficiency and noise.

3fill in blank

hard

Fix the error in the code that sets the direction control signals for the H-bridge.

Simulink

direction_signal = [1];  % 1 for forward, 0 for reverse

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

ATrue

B0

C'forward'

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using string values or boolean True/False which cause simulation errors.

The direction signal must be numeric 1 or 0 for Simulink to interpret it correctly.

4fill in blank

hard

Fill both blanks to create a dictionary mapping motor states to PWM duty cycles.

Simulink

duty_cycles = { 'forward': [1], 'reverse': [2] }

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

A0.8

B0.5

C0.2

D1.0

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning the same duty cycle to both directions, which doesn't simulate direction change.

Forward direction uses 80% duty cycle, reverse uses 20% to control motor speed and direction.

5fill in blank

hard

Fill all three blanks to define the H-bridge output signals based on PWM and direction.

Simulink

outputs = { 'high_side': pwm_signal if direction == [1] else 0, 'low_side': pwm_signal if direction == [2] else 0, 'enable': [3] }

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

A1

B0

CTrue

DFalse

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up direction values or using False for enable which disables output.

High side is active when direction is 1 (forward), low side when direction is 0 (reverse), and enable is True to activate the H-bridge.

Practice

1. What is the main purpose of an H-bridge in motor control simulation?

easy

A. To control the direction of the motor by switching current paths

B. To increase the motor speed beyond its maximum rating

C. To convert AC power to DC power for the motor

D. To measure the temperature of the motor during operation

Solution

1. Step 1: Understand H-bridge function

   An H-bridge is designed to control the direction of current flow through a motor.

2. Step 2: Relate to motor control

   By switching current paths, it changes motor rotation direction safely.

3. Final Answer:

   To control the direction of the motor by switching current paths -> Option A

4. Quick Check:

   H-bridge controls motor direction = A [OK]

Hint: Remember: H-bridge switches current to change motor direction [OK]

Common Mistakes:

• Confusing H-bridge with power conversion devices
• Thinking it measures motor parameters
• Assuming it increases motor speed directly

2. Which Simulink block is typically used to represent the switches in an H-bridge driver simulation?

easy

A. Scope block

B. Gain block

C. Integrator block

D. Switch block

Solution

1. Step 1: Identify switch representation

   In Simulink, the Switch block models on/off states like switches in an H-bridge.

2. Step 2: Exclude other blocks

   Gain changes signal magnitude, Integrator accumulates signals, Scope displays signals, none act as switches.

3. Final Answer:

   Switch block -> Option D

4. Quick Check:

   Switch block models switches = A [OK]

Hint: Switch block simulates on/off control in Simulink [OK]

Common Mistakes:

• Choosing Gain block thinking it switches signals
• Confusing Scope with control elements
• Using Integrator block for switching

3. Consider this Simulink logic for an H-bridge driver:
Switch1 = ON, Switch4 = ON, Switch2 = OFF, Switch3 = OFF
What is the motor direction output?

medium

A. Motor direction is undefined

B. Motor rotates forward

C. Motor is stopped

D. Motor rotates backward

Solution

1. Step 1: Analyze switch states

   Switch1 and Switch4 ON means current flows in one diagonal path of the H-bridge.

2. Step 2: Determine motor direction

   This diagonal current flow causes the motor to rotate forward.

3. Final Answer:

   Motor rotates forward -> Option B

4. Quick Check:

   Diagonal switches ON = forward rotation [OK]

Hint: Diagonal switches ON means forward rotation [OK]

Common Mistakes:

• Assuming any two switches ON cause stop
• Confusing diagonal switch pairs
• Ignoring OFF switches effect

4. In a Simulink H-bridge model, the motor does not rotate even though Switch1 and Switch4 are ON. What is the most likely error?

medium

A. Switch1 and Switch4 are connected incorrectly in the model

B. The motor block is missing from the Simulink model

C. Switch2 and Switch3 are also ON causing a short circuit

D. The power supply block is disconnected

Solution

1. Step 1: Check switch connections

   If Switch1 and Switch4 are ON but motor doesn't rotate, wiring may be incorrect.

2. Step 2: Exclude other causes

   Switch2 and Switch3 ON causes short, not no rotation; missing motor or power would cause no output but question states switches ON.

3. Final Answer:

   Switch1 and Switch4 are connected incorrectly in the model -> Option A

4. Quick Check:

   Incorrect wiring stops motor despite switches ON [OK]

Hint: Check wiring if switches ON but motor stays still [OK]

Common Mistakes:

• Assuming short circuit causes no rotation instead of damage
• Ignoring wiring errors
• Overlooking power supply connection

5. You want to simulate a motor braking effect using an H-bridge in Simulink. Which switch configuration achieves this?

hard

A. Turn ON both switches on opposite diagonal (Switch1 and Switch4 ON)

B. Turn ON both switches on the same side (Switch1 and Switch2 ON)

C. Turn ON both switches on the same diagonal (Switch2 and Switch3 ON)

D. Turn OFF all switches

Solution

1. Step 1: Understand braking in H-bridge

   Braking is done by shorting motor terminals, which happens when switches on the same diagonal are ON.

2. Step 2: Identify correct switch pair

   Switch2 and Switch3 ON short motor terminals, causing braking effect.

3. Final Answer:

   Turn ON both switches on the same diagonal (Switch2 and Switch3 ON) -> Option C

4. Quick Check:

   Same diagonal switches ON = braking [OK]

Hint: Same diagonal switches ON short motor for braking [OK]

Common Mistakes:

• Confusing diagonal switches with braking
• Turning OFF all switches thinking it brakes
• Using opposite diagonal switches for braking