H-bridge driver simulation in Simulink - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding the H-bridge operation

Which statement best describes the function of an H-bridge in motor control?

A It converts AC voltage to DC voltage for the motor.

B It increases the voltage supplied to the motor to boost speed.

C It measures the motor speed and adjusts the current accordingly.

D It allows the motor to run forwards and backwards by controlling the polarity of the voltage applied.

💡 Hint

Think about how direction control is achieved in DC motors.

An H-bridge switches the polarity of the voltage across the motor terminals, enabling forward and reverse rotation.

❓ Predict Output

intermediate

Simulink block output for H-bridge input signals

Given a Simulink model of an H-bridge with inputs IN1=1, IN2=0, what is the expected output voltage polarity across the motor terminals?

Simulink

IN1 = 1;
IN2 = 0;
% Output voltage polarity: +V to terminal A, 0V to terminal B

A Both terminals are at 0V (motor stopped).

B Motor terminal A is negative, terminal B is positive (reverse rotation).

C Motor terminal A is positive, terminal B is negative (forward rotation).

D Both terminals are at positive voltage (short circuit).

💡 Hint

Check which input is high and which is low to determine polarity.

IN1=1 and IN2=0 causes the H-bridge to apply positive voltage to terminal A and ground terminal B, resulting in forward rotation.

❓ data_output

advanced

Simulated PWM signal effect on motor speed

In a Simulink H-bridge model, a PWM signal with 50% duty cycle is applied to the enable pin. What is the expected average voltage across the motor terminals?

Simulink

PWM_duty = 0.5;
V_supply = 12; % volts
V_avg = PWM_duty * V_supply;

A 6 volts average voltage across the motor terminals.

B 12 volts average voltage across the motor terminals.

C 0 volts average voltage across the motor terminals.

D 24 volts average voltage across the motor terminals.

💡 Hint

Average voltage is supply voltage multiplied by PWM duty cycle.

With 50% duty cycle PWM, the motor receives half the supply voltage on average, so 6 volts.

🔧 Debug

advanced

Identify the error in H-bridge input signals causing short circuit

In a Simulink H-bridge model, both IN1 and IN2 inputs are set to 1 simultaneously. What is the likely outcome?

A Motor runs at maximum speed forward.

B Short circuit occurs because both high-side switches are on, damaging the circuit.

C Motor runs at maximum speed reverse.

D Motor stops safely with no voltage applied.

💡 Hint

Consider what happens if both sides of the H-bridge are connected to the supply voltage at the same time.

Both IN1 and IN2 high turns on both high-side switches, causing a direct short from supply to ground, which can damage components.

🚀 Application

expert

Designing a Simulink model for bidirectional motor control

You want to simulate a bidirectional DC motor control using an H-bridge in Simulink. Which input signal combination correctly achieves forward, reverse, and stop states?

A Forward: IN1=1, IN2=0; Reverse: IN1=0, IN2=1; Stop: IN1=0, IN2=0

B Forward: IN1=0, IN2=0; Reverse: IN1=1, IN2=1; Stop: IN1=1, IN2=0

C Forward: IN1=1, IN2=1; Reverse: IN1=0, IN2=0; Stop: IN1=0, IN2=1

D Forward: IN1=0, IN2=1; Reverse: IN1=1, IN2=0; Stop: IN1=1, IN2=1

💡 Hint

Recall the polarity needed for forward and reverse motor rotation and what input combination stops the motor.

Forward rotation is achieved by IN1=1 and IN2=0, reverse by IN1=0 and IN2=1, and stop by both inputs low (0,0) to avoid short circuits.