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True RMS and Duty cycle calculation
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Topic: True RMS and Duty cycle calculation (Read 746 times)
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rrn
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Posts: 5
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True RMS and Duty cycle calculation
«
on:
December 03, 2021, 04:03:35 am »
Can someone help with calculating modified sine wave true RMS value and also how to Control PWM dutycycle to maintain fixed output.
Example: input volatge 100Vdc.
Need to maintain fixed Vrms 50VAC
Frequency = 50hz
Modified sine wave same as in the picture
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gcewing
Regular Contributor
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Re: True RMS and Duty cycle calculation
«
Reply #1 on:
December 03, 2021, 07:22:00 am »
For PWM with duty cycle d,
Vrms = sqrt(d * Vin**2) = sqrt(d) * Vin
so
sqrt(d) = Vrms / Vin
or
d = (Vrms / Vin) ** 2
So for Vin = 100V and Vrms = 50V, you want d = 1/4.
The frequency doesn't come into it.
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True RMS and Duty cycle calculation
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