Electronics > Projects, Designs, and Technical Stuff
Power and control independantly 100+ 24V Halogen lamp simultaneously
damien22:
--- Quote from: mariush on April 02, 2019, 11:39:54 am ---My thoughts went to using 24v lead acid batteries (or two in series) to power segments of your 100 lamps... for example 10 groups of 10 lamps each to get the power consumption more even instead of so pulsed.
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That is actually a very good Idea!
damien22:
--- Quote from: Ian.M on April 02, 2019, 02:46:52 pm ---Another option would be as many 28V AC transformers.
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I checked this solution but the cost still remain higher than having a huge power supply, and I prefer not to use dirt cheap power supply as to not having a failure.
Concerning control, it is not an issue, the initial design uses a dsPIC that generates the PWM and measure the photodiode feedback, all this is controlled over a serial daisy chained bus controlled by software.
Concerning driving the bulb directly by PWM, I don't know how much EMI would that generate given that there are about 15cm cables to the lamps. Current limiting would be possible but probably would require very short timing which I don't know can be handled with standards MCU and might require some more analog control. Probably a coil would still be required somewhere or perhaps oversized MOS.
I think it's not easy to provide 26VAC, it would require quite a massive transformator.
Zero999:
--- Quote from: Cyberdragon on April 03, 2019, 03:31:31 am ---
--- Quote from: Zero999 on April 02, 2019, 03:17:40 pm ---
--- Quote from: Cyberdragon on April 02, 2019, 02:39:15 pm ---Definately DO NOT PWM incandescant lamps directly. The changing filament resistance (startup current) will reak havoc on your drive transistors, spending most of the energy trying to keep them glowing at all. You want to use triacs and chop the incoming AC to the bulbs. Just feed 24VAC down a few bus lines and chop it at each lamp with a few control lines.
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Howå is phase control any better than PWM?
PWM is pretty standard for dimming a filament lamp run on DC. I've done it before without any problems. The filament resistance will always be lower on start up, just make sure the switch, be it a transistor or thyristor, can handle the surge. In any case, the power dissipation in the switch will be less, when the lamp is dimmed, as the low duty cycle will outweigh the increased switching losses.
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We're not talking about a single house lamp here, it's 10KW worth of 100W bulbs. Also, if you zero cross switch the triac properly it will make a difference compared to a hard square wave startup.
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On switch per lamp, with the switching interleaved so not all lamps are being turned on and off simultaneously, will alleviate a lot of noise problems.
--- Quote from: damien22 on April 03, 2019, 07:41:24 am ---
--- Quote from: Zero999 on April 02, 2019, 11:35:38 am ---Why use halogen lamps? Use LEDs of course. It will make this much easier. Even if it costs a little more, the reduced energy consumption will make it cheaper in the long run.
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Because LED at this wavelength (that we need) and power would run somewhere around 300'000$
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What wavelength is that? Presumably this is used as an IR heater, rather than light.
Gyro:
--- Quote from: damien22 on April 03, 2019, 07:51:57 am ---
--- Quote from: Ian.M on April 02, 2019, 02:46:52 pm ---Another option would be as many 28V AC transformers.
--- End quote ---
I checked this solution but the cost still remain higher than having a huge power supply, and I prefer not to use dirt cheap power supply as to not having a failure.
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Did you factor in the cost of the huge copper cables and installation needed to keep voltage drop within acceptable limits? (I was once involved with an SELV traffic junction controller project, power consumption was small in comparison!).
damien22:
--- Quote from: Gyro on April 03, 2019, 10:43:54 am ---
--- Quote from: damien22 on April 03, 2019, 07:51:57 am ---
--- Quote from: Ian.M on April 02, 2019, 02:46:52 pm ---Another option would be as many 28V AC transformers.
--- End quote ---
I checked this solution but the cost still remain higher than having a huge power supply, and I prefer not to use dirt cheap power supply as to not having a failure.
--- End quote ---
Did you factor in the cost of the huge copper cables and installation needed to keep voltage drop within acceptable limits? (I was once involved with an SELV traffic junction controller project, power consumption was small in comparison!).
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Yes, it's actually another post on this forum, we use tin plated aluminum busbar.
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