we wish to seprate ac and dc power signals from a mixed (dc with ac ripples) power signal and drive ac as well as dc loads simultaneously. Initially we are inteserted in applying the very basic principles of resonance. Your suggestions are highly welcomed.
Hello, Varun!
The basic technique of separating dc and ac components from the mixed signal is to apply Fourier transformation (Fast Fourier Transformation, FFT). FFT allows us to come from time scale to the frequency scale and extract the DC signal and amplitude and phase of each harmonic, i.e. the sinusoidal signals with some determined frequency that shapes the original mixed signal. But the mixed signal has to have permanent shape throughout the whole time scale, otherwise FFT gives us uncorrect picture. To overcome it, we can apply wavelet transformation. The basic concept of all of it, including main equations, you can find in Wikipedia, for example.
Regards.
Thanks Alexander Pugachev,
My objective is to separate ac and dc experimentally not analytically. As we wish to drive ac as well as dc loads from the output of SMPS which is dc with ripples.
Hello Varun,
There are some methods to separate DC and AC signals.
Can you put some oscillograms or any more informations about levels of voltages and currents? Resonant circuit is a bit hard to apply in changeable environment.
Need a signal or power which one is needed.
Sepearte with dc filter and remaining signal are ac signal. Dc filter power for dc load and another signal is used for ac load.
Thanks Dr. Navdeep Singh,
AC and DC power is needed separately (from a mixed source) to drive ac and dc loads.How filters can be used so that we may get both ac as well as dc useful power and both ac and dc powers may drive ac and dc loads simultaneously...?
Thanks Tomasz Zyska,
Can you provide me some literature on separating ac and dc power signals using the principles of Resonant Circuits. I want to separate ac and dc power signals from the output of dc-dc converter which is dc with ac ripples, and I want to drive ac and dc loads simultaneously from dc-dc converter's output.
AC is easily decoupled via an adequate capacitor (blocking the DC component).
The same applies for decoupling the DC component via an appropriate choke.
Resonant circuits are only useful to decouple an AC component of a specific frequency. If this is what you need, you should succeed using a serial LC circuit tuned to this frequency. In this specialized case it is recommended to block the DC "outlet" with a parallel LC circuit tuned to the same frequency.
What's tricky with this concept is the fact, that the parallel LC circuit is easily overloaded if the source impedance of the AC frequency is too low - meaning that a part of the energy of this specific frequency will still go to the DC load.
Thank you veru much U. Dreher for your suggestions.
In my case, I am interested in extracting specific frequency ac power signal as well as dc from the output of dc-dc converter which is dc with ac ripples.
I am having problem in fully understanding the concept which you have mentioned. Can you please explain in detail and if possible with some schematic?
Hello,
I do not have schematics at hand.
To understand the basics, https://en.wikipedia.org/wiki/LC_circuit - sections "Series LC circuit" and "Parallel LC circuit" should help you.
For further concepts, data sheets and application notes about AS-i (Actor Sensor Interface) interfaces should be able to guide you further: AS-i implements communication over the same wire the DC supply is provided - roundabout the same as your application. Basics: https://en.wikipedia.org/wiki/AS-Interface
Hello Varun,
You didn't write more informations about AC, DC, V and I levels.
If you have a plan to build a resonant converter pls check some information about Resonant Circuits (for power conversion).
You can find more here: http://www.ti.com/lit/ml/slup085/slup085.pdf
and here: http://scholar.lib.vt.edu/theses/available/etd-09152003-180228/unrestricted/Ch4.pdf
Thank you very much, U. Dreher, for your suggestions.
I have AC+DC, with DC voltage = 50V, AC RMS voltage = 15V, AC frequency = 500Hz, I wish to extract AC and DC, using the resonant circuit (i.e., by using series and parallel tuned LC circuits) as suggested by U. Dreher. Why parallel LC circuit is required in the specified case mentioned by U. Dreher. If possible, please provide some study material on the specified case of the resonant circuit to extract ac and dc.
50 V DC plus on overlay of 15 V (amplitude or VSS?) @ 500 Hz ? (Edit: Oh - missed the "RMS". Anyway ...)
AC is easily separated by using some capacitor (1 µF to strt with).
DC separation is somehow 'trickier' as we're dealing with attenuation: You'll need a serious choke plus a serious capacitor. The LC product should be something beyond 1E-6 s. like I fiddled a bit with some simulation (schematics attached) on LTSpice: 2.2 mH and 10.000 µF are nice values - leaving a ripple of some 0.14 VPP for an AC overlay of 30 VPP.
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