PWM generation in Simulink - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does PWM stand for and what is its main purpose?

PWM stands for Pulse Width Modulation. It is used to control the amount of power delivered to electrical devices by switching the signal on and off rapidly.

beginner

In Simulink, which block is commonly used to generate a PWM signal?

The 'PWM Generator' block or a combination of 'Compare To Constant' and 'Repeating Sequence' blocks are commonly used to create PWM signals in Simulink.

beginner

How does changing the duty cycle affect the PWM signal?

Changing the duty cycle changes the proportion of time the signal is ON versus OFF. A higher duty cycle means the signal is ON longer, delivering more power.

intermediate

What role does the carrier signal play in PWM generation in Simulink?

The carrier signal, often a sawtooth or triangular wave, is compared with the reference signal to create the PWM waveform by switching ON when the reference is higher.

beginner

Why is PWM useful in controlling motors or LEDs?

PWM allows precise control of power without wasting energy as heat, making it efficient for controlling speed of motors or brightness of LEDs.

What happens to the output power when the PWM duty cycle increases?

A Output power increases

B Output power decreases

C Output power stays the same

D Output power becomes zero

Increasing the duty cycle means the signal is ON longer, so more power is delivered.

Which waveform is typically used as the carrier signal in PWM generation?

A Sine wave

B Triangular or sawtooth wave

C Square wave

D Random noise

Triangular or sawtooth waves are used as carrier signals to compare with the reference signal for PWM.

In Simulink, what block can be used to compare the reference signal with the carrier signal?

A Sum block

B Gain block

C Compare To Constant block

D Integrator block

The Compare To Constant block can be used to generate PWM by comparing signals.

What is the main advantage of using PWM for controlling devices?

A It provides precise power control efficiently

B It wastes more energy

C It is slower than analog control

D It only works for LEDs

PWM controls power efficiently by switching signals rapidly without wasting energy.

What does a 50% duty cycle mean in a PWM signal?

A Signal is ON 25% of the time

B Signal is always ON

C Signal is always OFF

D Signal is ON half the time and OFF half the time

A 50% duty cycle means the signal is ON for half the period and OFF for the other half.

Explain how PWM signals are generated in Simulink using carrier and reference signals.

Think about how the carrier wave is compared to the reference to create ON/OFF pulses.

Describe why PWM is an efficient method for controlling power in devices like motors and LEDs.

Consider how turning the signal ON and OFF rapidly saves energy compared to continuous control.