Guru
Joined: 13/10/2014
Location: AustraliaPosts: 1846
| Posted: 09:36am 25 Dec 2022 |
Hello all, I thought I would start a thread on yet another 240vac Inverter build. The reason to start this now is the confusing statements on various builds concerning the expected use and capability of these Low frequency Toriod inverters.
From what I have read on line and almost every forum, the typical High Frequency inverters are not any good at starting heavy inductive loads.
I assume this HF inverter to be something like a "pure sine wave" 24/48vdc to 240Vac unit with a Hi frequency DC inverter generating around 360v-390v DC feeding a DC to AC PWM IGBT output stage and a large inductive filter for 230v AC. (No big Transformer)
Strangely, I have a $680 made in China 5kW/10kW surge inverter just like this. It's a 24v inverter and it starts a big 25 year old massive 2.5hp air Compressor that was the bane of every work site if put on any kind of extension lead - used to burn out the motor from slow startup/stalling.
The peak startup current in to the inverter of the above unit is 480A @ 26V. Expensive DC clamp meter with a slow decay hold function, a late model DC clamp meter and my own DC 600Amp clamp used to monitor the Load current with special peak hold coding for catching any glitch on the displayed graph at very high sample rates.
It also starts our 2.5HP heavy induction motor Band-Saw at 410A surge, huge Bench grinder (induction), 2KW through wall workshop Vacuum, Air conditioner, Cloths dryer, small Oven, all workshop lighting computers, an so on, and until recently, a small 2.4kW water heater.
I did have to strip that inverter down when I got it 10 months ago and fix all the poor finish and leftover aluminum filings, PCB gunk and poor fitting heat sinks, but it's got all high quality oversized components.
Now from what I have read, this should have destroyed itself, and I thought so to, but it is what it is. I could not believe it could start that Compressor, had to go back and look to make sure it wasn't on mains.
I want something that is not a ticking time bomb, hence my desire to build a Low frequency inverter, which is supposed to be the best with these kinds of induction load. But I see things like, you should soft start with these induction loads? seriously? you mean like a brownout condition? The Air compressor and Band-saw are just going to love that.
So there are conflicting messages, and before I start on any big Toriod inverter build, I'm hoping someone can shed some light as to which information is correct.
I mean 480A @ 26v is crazy and it HF inverter never misses a beat [YET]. I'm changing to nominal 48V so current will be halved, but I have an uneasy feeling after reading some of the failure modes of these LF Toriod inverters into complex high power shock loads?
BTW: My wife has forgotten that we were on Solar and sometimes tries to start a Huge 3HP dust extractor, well it gives it a good try but the Surge time is only 3 seconds, so the Inverter switches itself off and restarts. The NVR relay drops out on the Extractor and no harm done, just switch over to mains to start the Extractor, can then switch back to Solar and all's good.
Please don't read this as anything but an observation from way to much reading, and more a HELP call, or a Plea to enable me to make the most informed decision on how to proceed.
I was going with the Oz inverter, but I saw the NanoVerter and Warp, and love some the brilliant work done on all of these but still some niggles?
Yes I know it's asking a lot, but surely if a $680 24v HF inverter can do it without blowing up, one of these should.
BTW: The HF inverter uses a slight variation of the EGS002 SPWM board, pin for pin compatible anyway, looks ALMOST the same.
Have Toroids - can wind
I hope 
Mike.
NANO Inverter: Full download - Only Hex Ver 8.1Ks