Arduino Powered AC power supply - Page 1
Forum section: electronics / beginners

author: gmi109
author_rank: Contributor
timestamp: October 15, 2015, 03:25:24 am
content: Hello, I am trying to make an Arduino powered AC power supply. The idea here is that I can make a low current power supply that I use to output different frequency 50/60 Hz and voltage 120/240VAC to test switching AC/DC power supplies that I plan on making for future projects.So far, I'm thinking that I can use an Arduino/DAC combination to generate a nice 0-5V sine wave at 50 or 60 Hz. This sine wave would need to be amplified to ~12Vrms and then put through a 12V/240V transformer. The part that is getting me stuck is how to amplify the sine wave. I'm a beginner and I'm not really sure of the best way to amplify this signal and have the appropriate amperage necessary for the transformer (I'm shooting for ~30 watts).So my question is, what would you guys recommend for going from the 0-5V sine wave to either a +/-17 V sine wave or a +14/0 V sine wave (I believe both result in a 12Vrms sine wave?)? Right now I'm thinking it will have to be some combination of OP-amp and transistors/MOSFETs?Thanks for any input you guys can provide.

author: amyk
author_rank: Super Contributor
timestamp: October 15, 2015, 03:50:16 am
content: An Arduino? Forthat?What you're looking for is an "inverter". Use that search term and you'll find more info...

author: gmi109
author_rank: Contributor
timestamp: October 15, 2015, 04:03:28 am
content: Quote from: amyk on October 15, 2015, 03:50:16 amYes, I want an Arduino. Most of the inverter schematics that I've looked at so far don't have the ability to easily switch between 50/60 hz and don't have the ability to set current limits like one might want to for a "power supply". Not to mention a lot of the simple ones only do square waves.

author: Ian.M
author_rank: Super Contributor
timestamp: October 15, 2015, 04:21:50 am
content: How much load current capability do you need at 120V and at 240V?For low power loads, you may be able to use a step-up transformer driven by a class D audio amplifier module.

author: rs20
author_rank: Super Contributor
timestamp: October 15, 2015, 04:28:37 am
content: He/she said 30W in the OP.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 15, 2015, 04:32:17 am
content: There are dozens of audio power amp boards on Ebay that would boost your "line-level" sine wave up to something suitable for your step-up transformer.As @Ian.M suggested, you could use a class-D amplifier for better efficiency, lower cost, lower heat, etc.Not clear why you need a microcontroller to simply generate a switchable 50 or 60 Hz sine-wave?Unless there are other features you didn't mention, this seems like overkill.As a completely random example currently on Ebay...New IRS2092 Class D 200W Mono Audio Power Amplifier AMP Assembled Board -- US$ 16.51http://www.ebay.com/itm/New-IRS2092-Class-D-200W-Mono-Audio-Power-Amplifier-AMP-Assembled-Board-/141686135851?hash=item20fd26dc2b

author: gmi109
author_rank: Contributor
timestamp: October 15, 2015, 04:32:36 am
content: Quote from: Ian.M on October 15, 2015, 04:21:50 amYes, I'm targeting about 30 watts. I've never dealt with class d audio amplifier circuits before, I'll look into that. Thanks for the suggestion

author: gmi109
author_rank: Contributor
timestamp: October 15, 2015, 04:36:00 am
content: Quote from: Richard Crowley on October 15, 2015, 04:32:17 amI realize that it is kind of overkill. I was wanting to have a nice LCD display where I could set the voltage/frequency and set a current limit so that it could cut the output if the selected current was exceeded. I'll definitely look into a class D amplifier, especially if there are cheap ones ready to go on ebay. Thanks for the suggestions!

author: Ian.M
author_rank: Super Contributor
timestamp: October 15, 2015, 04:38:37 am
content: One of the reasons that you may want to use a MCU controlled solution is if you want to be able to simulate mains transients and various types of waveform dstortion.

author: gmi109
author_rank: Contributor
timestamp: October 15, 2015, 04:43:57 am
content: Quote from: Ian.M on October 15, 2015, 04:38:37 amI hadn't thought of that, but that would certainly be something it could do too.

author: Cliff Matthews
author_rank: Unknown
timestamp: October 16, 2015, 12:20:21 am
content: I thought Class-D amps were created to give audiophiles something to gripe about..so theyareuseful!Pardon my doubt, but isn't the class-D audio output "tuned" for the impedance (damping, etc..) of a speaker? Wouldn't a transformer wired for step-up and just inches away, present a very different load? or require more output filter? Although they show 200-watts, it's likely only trustworthy for 50-watts in this application (and pardon the suspicion, somehow those nice Nichicon caps may end-up being CapXcon's by the time it arrives).

author: rs20
author_rank: Super Contributor
timestamp: October 16, 2015, 01:06:47 am
content: Quote from: Cliff Matthews on October 16, 2015, 12:20:21 amIf you think the distance of a load (inches vs meters) is relevant in the audio band, then I'm afraidyoumight be the audiophool here!Class D amps might come with output filters preinstalled for audio applications; although in the case of both transformers and speakers, the load is inductive and hence serves to smooth out the pulses coming from the Class D amp (which alternately shorts the output to Vcc and GND; once you add the inductive load, it's basically a buck converter). The OP wants 30W, the class D amp will output, say, 12V, that's 2.5A output, or an impedance of 12V / 2.5A = 4.8 ohms, which is pretty close to the mark for a typical speaker.

author: Cliff Matthews
author_rank: Unknown
timestamp: October 16, 2015, 01:23:45 am
content: Quote from: rs20 on October 16, 2015, 01:06:47 amThat was in jest. I find alternate use of cheap ebay modules interesting and honestly thought there would be a disparity with the loads.Yes, I have humorous debate with an audio-fool family member about his Threshold "Stasis 500" amplifier and monster cables etc..

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 16, 2015, 03:01:09 am
content: Quote from: gmi109 on October 15, 2015, 04:03:28 amwhats the point?50 and 60 dont have much difference...Quote from: gmi109 on October 15, 2015, 04:03:28 amto current limit a 120/240V mains system means at one point your psu is going to lower that 120/240V which is not going to happen in real life... so to simulate that system on a offline smps is pointless imho... current limit in most offline/ac smps i've seen at least is happening in the step down (smps) transformer, thats where you need to look at imho, ymmv..

author: gmi109
author_rank: Contributor
timestamp: October 16, 2015, 03:42:14 am
content: Quote from: Mechatrommer on October 16, 2015, 03:01:09 amI understand that. It's more of a safety feature to prevent me from blowing up my AC/DC switching converters that I plan on testing with this. The same reason that you have CC modes on DC power supplies....