1KW Inverter / General Science and Electronics / Forums

Forums

4hv.org :: Forums :: General Science and Electronics

« Previous topic | Next topic »

1KW Inverter

Move Thread

LAN_403

HDR

Mon Dec 31 2007, 02:50AM

Registered Member #1165 Joined: Sun Dec 09 2007, 04:41AM
Location: GA, USA
Posts: 35

After seeing the similarities between the circuit I used for my SSTC and a TL494 based power inverter, I decided to see if I could make one. The inverter circuit I found only put out a few watts, but I want to make one that can handle at least a KW. Hows this circuit look?

I want to use it for power backup of my server and some networking equipment, since it only gets about 2 minutes on the 300VA units I got free after rebate (supposed to last 15 mins). The server is heavily overclocked and draws 300W on average, peaking at almost a KW under heavy loading. My 600W car inverter can't even power it for more than a few mins if I load both cores to 100% and do a file copy from one hard drive to the other at the same time...

Sulaiman

Mon Dec 31 2007, 09:03AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Designing an inverter is quite a complex task, your basic design may work.
Designing an inverter that works reliably and handles all manner of fault conditions requires experience,
your design will need MANY improvements, I'd guess about a year should be enough if you keep at it.

Considering the cost/value of the load, using an unreliable UPS seems unwise.
Check also that your load (the PC PSU) will be ok with a squarewave input.

Electroholic

Mon Dec 31 2007, 09:12AM

Registered Member #191 Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720

From what you said, it seems the problem can be solved with just a bigger bank of batts???

Steve Conner

Mon Dec 31 2007, 12:35PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

The problem can be solved by dumpster diving a bigger UPS

Every one I ever found was working apart from bad batteries. If you want to learn about inverters, dumpster dive two and take the other one apart...

Also, did you read the part of my thesis dealing with inverters:

Why on earth would you want to overclock a server anyway? Surely reliability is more important than speed, and a server is usually limited by its network bandwidth anyway. Unless you're into F@H and the like, which is just an easy way to donate electricity to biotech research

Marko

Mon Dec 31 2007, 12:41PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

You definitely don't need gate drivers for 60Hz.

pullup resistors in range of few hundred ohms will be more than OK, and you might actually want to increase your gate capacitance by additional gate-source cap.

HDR

Mon Dec 31 2007, 05:27PM

Registered Member #1165 Joined: Sun Dec 09 2007, 04:41AM
Location: GA, USA
Posts: 35

Its more of a home server and video encoding computer than a commercial server. Even overclocked to 150% its rated speed, it has run 3 months continuously, and has not crashed in 2 years. I host my own email and a few websites for friends, it acts as the router for my home network, domain controller for a domain of 5 computers, and lets ms VPN in. It has a TV card and lets me stream any channel to my laptop wirelessly so I can watch TV anywhere.

I have tried using bigger batteries, but the 600w inverter shuts down due to overheating/overload, not low battery. It has no issues with square wave input as thats what my current UPS outputs. I have an older UPS that will allow square wave input, so I actually have 2 in series running the computer right now. I will probably use my home made UPS to feed into the other one so it can provide fast switchover and surge protection. One hack I have in right now to make it run longer when the power goes out is that I have all the hard drives (8) and fans (5, 1A each) connected to a different PSU on a different UPS, which keeps it from overloading either one, but I don't like having to rely on the motherboards fan speed sensors to shut down the system if the fan/hard drive UPS shuts down before the one for the rest of the system...

Where would you dumpster dive a UPS from? Especially a KW unit?

Steve Conner

Mon Dec 31 2007, 07:29PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Well, it's not quite 1kW, but my home server currently runs off a APC Smart UPS 700 that I found in the junk heap at my old workplace.
It also does nearly everything that yours can, on a power consumption of 50-75W. It doesn't stream TV because the TV card I had wasn't supported under Linux, and it doesn't host e-mail because I can't be bothered dealing with spam. I'm sure it would be much slower at encoding video too, but since it runs all the time, it could take all night if it wanted to.

FWIW, if a supply can run off square wave, it might also be capable of running off 160 or 320V DC.

HDR

Mon Dec 31 2007, 08:03PM

Registered Member #1165 Joined: Sun Dec 09 2007, 04:41AM
Location: GA, USA
Posts: 35

Actually, I just got a better idea, so the inverters out... I'll just insert a custom 2nd PSU into the rear drive bay and supply the hard drives, fans, and dvd drives directly off the batteries with 12V and 5V voltage regulators... Thats around 20A since I have 8 hard drives that draw 10-15 watts each and 5 fans that draw 1-2 amps each... Much easier, all I need are some high speed relays and 2 big capacitors to keep things powered during the transition...already have that stuff on a seperate PSU anyway. And I can even just power the fans off the battery full time with a charger. 300VA UPS onnected to a bigger battery should be able to handle the motherboard alone pretty easily.

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob