signallimiter-pwm

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signallimiter-pwm

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Signal\Block Diagram Non-Linear

Use

Domains: Discrete, Continuous. Size: 1-D. Allowed in: Block Diagrams.

Description

Pulse width modulation (PWM) is a powerful technique for controlling analog circuits with a processor's digital outputs. PWM is employed in a wide variety of applications, ranging from measurement and communications to power control and conversion. The output of a PWM block is a pulse train. The duty cycle, (the time that a pulse is on divided by the time the pulse is off) is proportional to the value of the input signal if the input is within the range < -input_amp , +input_amp >. For Bipolar PWM the output signal witches between a positive and a negative value. For Unipolar PWM the output signal witches between zero and positive or negative value.

 

input

bipolar PWM

Unipolar PWM

 

> input_amp

100% output_amp

0% -output_amp

100% output_amp

0%      0

 

input_amp

100% output_amp

0% -output_amp

100% output_amp

0%     0

 

0.5*input_amp

75% output_amp

25% -output_amp

50% output_amp

50% 0

 

0

50% output_amp

50% -output_amp

0

 

-0.5*input_amp

25% output_amp

75% -output_amp

50%  0

50% -output_amp

 

-input_amp

0% output_amp

100% -output_amp

0%       0

100% -output_amp

 

<-input_amp

0% output_amp

100% -output_amp

0%       0

100% -output_amp

 

An example is shown in the graph below. The parameter input_amp is equal to 1 and the parameter max output is equal to 5. The frequency of the PWM signal is 10 Hz.

SignalLimiter-PWM

Bipolar and Unipolar PWM conversion.

Interface

Inputs

Description

input

 

 

Outputs

 

output

 

 

Parameters

 

f

input_amp

output_amp

The modulating frequency [Hz].

Maximum value of the input signal.

The output value will switch between output_amp, 0 and -output_amp.