Find the voltage from a PWM signal

I want to use Simulink to calculate the Average voltage from a PWM Signal. Although I'm not entirely sure how should do it so it works robustly.

The eventual use is to have it working in real time using xpc target but I wondered if anyone could explain even a way to calculate it in a continuous way even.

To anyone that does not know a PWM signal is a Pulse signal that width can be modulated , hence the name.

The voltage of a PWM is the Peak voltage * duty cycle

The duty cycle is the percentage of that the signal is "ON" in any one period

so if the period (of the signal) is 5 seconds and the signal is "ON" for 2 seconds the duty cycle is 40 %

So if we look at the picture above we see 5 examples.

Lets say my on voltage is 20 Volts and my off voltage is 0 Volts

So with a duty cycle of 100 %

Average volt = 20 * 1 = 20 Volts

80 % = 16 Volts

50% = 10 Volts

20 % = 4 Volts

0 % = 0 Volts

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So Basically what I want is a way to calculate the:

Peak Voltage of the signal being sent (reseting after every new period)

Duty Cycle of the Signal

and possibly the frequency of the signal

Thanks any advice welcome

Answer 1

[Suneesh]

The following example shows how to calculate duty cycle (requires Signal Processing toolbox):

http://www.mathworks.com/help/signal/ug/duty-cycle-of-rectangular-pulse-waveform.html

You can use:

[D,INITCROSS,FINALCROSS,NEXTCROSS]= dutycycle(x)

to find out period(frequency), and then use this information for Peak Voltage.

You may use this function in a MATLAB Function block so that you can use it in a Simulink model. Also, a comon method of determining period od a function is by calculating its auto-correlation for which a Simulink block is available in the DSP System toolbox.

Answer 2

[paranandi lakshmi narayana]

hello sir i am doing project on wind energy conversion system using pmsg. i used diode bridge rectifier with boost converter. but when i am applying gate pulses to the boost converter the output of the pmsg got totally changed.i don't know whats happening there but intially without applying gate pulses i got right answer but now its completely changed. please suggest what to do

[Walter Roberson]

I recommend that you create a new Question for that matter.

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

[An]

Hello!

I have exactly the same problem. Did you manage to solve the problem?