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PWM

Generate ideal pulse width modulated signal corresponding to input duty cycle

• Library:
• Simulink / Discontinuities

Description

Use the PWM block to generate an ideal pulse width modulated signal.

Pulse Width Modulation (PWM) is a technique for encoding an analog signal using square pulses. This encoding is achieved by controlling the fraction of one period of the square wave that is set to high. This fraction is the duty cycle of the signal. The relationship between the modulated signal and the input duty cycle can be simply described as:

$\overline{y}=D{y}_{max}+\text{​}\left(1-D\right){y}_{min}$

where ymax and ymin are the upper and lower bounds of the duty cycle, respectively. For the PWM block, the duty cycle is constrained to [0,1]. Thus the idealized PWM signal is proportional to the duty cycle D.

Ports

Input

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Desired duty cycle of the pulse P, specified as scalar within the range [0,1].

Data Types: double

Output

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PWM signal corresponding to the input duty cycle.

Data Types: double

Parameters

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Time between rising edges of consecutive pulses of the output signal. A smaller value represents a higher frequency pulse.

Select whether the block should operate in continuous or discrete sampling modes.

By default, the block uses continuous sampling mode as it improves simulation performance with variable step solvers.

Select discrete sampling mode if you need to:

• use a fixed-step solver

• generate code

• sample the block output

Specify the rate at which the block samples input duty cycle signal. This sampling rate becomes the resolution of the output pulse signal.

Dependencies

This parameter requires that Sampling mode is set to discrete

Enable this parameter to break algebraic loops containing the PWM block.

Note

Enabling this parameter causes a signal value of 0 or below for the Duty Cycle input to throw an error.

Data Types: Boolean

Block Characteristics

 Data Types double Direct Feedthrough no Multidimensional Signals no Variable-Size Signals no Zero-Crossing Detection no

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Version History

Introduced in R2020b