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Forum Index : Electronics : Hopefully? Another 48vdc-240vac Toriod Inverter build.
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poida Guru  Joined: 02/02/2017 Location: AustraliaPosts: 1418 |
these inverter boards are good. The one things that is not good is the size of the heatsinks but this one is just a test victim to be used for education. So it won't feel any pain no matter what happens. I made a similar board, based on the same totem pole drive but with 2oz copper and large heat sinks. I wanted to see what happens when I start the air compressor. this is what I found 11.5 kW through 3 FETs x 4 I think we all here see value in the robust nature of the low frequency inverter design. It can take nearly anything we give it and it just produces power. One thing I would like to note is the DC supply capacitor size. The Aliexpress board has tiny little caps. And it works. Works well. The boards we build here have huge capacitors, with massive capacitance. It helps I am sure, but maybe it's not that important. The large capacitance probably insulates the battery from large current fluctuations and that is probably a good thing. You won't see smoke from those sort of tests. I would put a temperature sensor on the heatsink though, if you intend to do some extended testing. wronger than a phone book full of wrong phone numbers |
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| poida Guru Joined: 02/02/2017 Location: AustraliaPosts: 1418 |
I do not want to hijack this thread with this discussion about the nano/pico firmware. So I think we best move on over to here to discus further your requirements. wronger than a phone book full of wrong phone numbers |
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KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679 |
Fine on the heat sinks, this test is being limited by the transformer, so must start winding one soon, but anything I do is monitored in every way, especially heating of any component. If I was going to use this (and I still might use it as a backup) it would obviously be modified in every way to survive. I'm afraid that any link you post for me on you testing, you can bet that I found it and read it, more than once, and I had  poida, I will be following you and wiseguy on the continuing nano/pico journey. I've read everything both of you have discussed and done with that, and earlier on, the EG8010 testing. If I'm still around I intend on trying your code version as well. It's all too hard. Mike. |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679 |
Started the Band saw, big induction motor - 12 kW @ 225 Amperes startup  Had to do it a few times because I had the meter set to 200A range, obviously it over ranged, set it to 400A and then forgot to set Peak hold.  No smoke got out. I just know that I'm going to regret saying that  The old 2.6kW heat Gun again, causes some kind of half wave pulse when on low heat, this causes a small kink in the LH side of the waveform and makes the Toriod give a low buzz to match the waveform kink, but otherwise runs fine, all silent @ 2.6kW on High heat. Choke is silent. . It's all too hard. Mike. |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2135 |
Perhaps that heat gun just uses a series diode for low power. Crack it open and gave a look. |
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Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1024 |
Sounds typical of heat guns, I had some experience, here probably read it anyway.  Cheers Aaron Off The Grid |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679 |
Yes, looks like a simple diode for the low power position. The only real complaint from the inverter was the Toriod humming along with it. HF inverter doesn't care BUT, that always has between 300w and 1.2kW load on it, so that likely dampens the output somewhat. Will have to give that a try on this inverter. Starting the bench grinder (induction motor) surprised me in that the 40+ amperes starting current didn't cause the slightest change at all to the AC waveform, and the inverter was silent during that surge and run time. Unfortunately the two meter high bandsaw can't be moved into my electronics area, so I went into the workshop, hit the big NVR switch and hoped for the best. I'm going to assume that my inductance tester and my interpretation of the results are correct and that the Choke I made does not get anywhere near saturation at 240A. . Edited 2023-01-18 17:02 by KeepIS It's all too hard. Mike. |
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| analog8484 Senior Member  Joined: 11/11/2021 Location: United StatesPosts: 108 |
Great project. Can you also test a full size microwave oven? It's a load that can cause significant inverter distortions when starting up. I use it to see the transient response performance of inverters. |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679 |
That likely depends on your Microwave? When our old Fridge Freezer and Microwave failed I made sure I bought the new Inverter type. I was thinking ahead to going off grid. The current HF inverter is running the whole House and Workshop. Huge side by side Fridge Freezer, 2.1kW Microwave, 2kW small Oven, Washing machine, Cloths Drier, small backup Chest Fridge Freezer with old style compressor, and all electronic and workshop power tools, big an small. That includes various Reverse cycle inverter Air conditioners. I made sure to never use a big central AirCon again for the same off grid reason. Just a few small units and good insulation. A 6m x 6m section of our larger color bond shed is cold on the hottest of days. From the various loads I've been throwing at it, I doubt this Test "transformer style" inverter will have a problem with any of them. The current HF inverter is running all of this from 24V, not 48v, which the inverter I'm building and this test unit are running from. I seriously doubt that a normal microwave is going to be anywhere near 225A @ 53V, which is as high as I have tested so far on this test unit. But if the Microwave is doing something like the Heat Gun and putting some horrendous unbalanced load distortion on the AC supply then I'd be dumping it. FYI the current Microwave normal start AND run current is 102A @ 27V, no ramp up, just huge square waves displayed on the Logging Graph of inverter DC input current. . It's all too hard. Mike. |
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| analog8484 Senior Member Joined: 11/11/2021 Location: United StatesPosts: 108 |
I have been holding off on getting inverter microwave ovens as I have read reports of horrible interference with WiFi and Bluetooth. |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679 |
I've had zero problems, WiFi power is set to as low as the settings will allow, about 10% from memory, and all blue BT devices connect as normal. Obviously again that too depend on the Microwave, I know some models are problematic. In any case, we only use it to defrost something occasionally, I'm not a fan of them It's all too hard. Mike. |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679 |
I decided to look a little further at the effect of these crap Heat Guns on Low. This was after finding that a big UPS (CHASEPOWER) that I use for the computers causes a slight flat top on the AC output?? When it's only supplying 200 watts to the PC's. It does not seem to cause any problems, and it's not headroom a the Inverter will run the Heat Gun @ 1.5kW and the waveform is as clean as a whistle. Here is what it does to the AC, and the HI/LO drive to the transformer [before the choke]. Before I started, I grabbed two Black ring toriods, thanks to wiseguy for telling me they were almost the same as the blue ones, so I added two to the other 6 and got the 51uH value I was looking for, this makes the output of the choke a lot cleaner and the waveforms are even better with the Heat gun. But if I use the E-core for more inductance, it's not as good, even with the E-Core on it's own. I really need to look more into this with bad loads - or not The Heat gun draws about 800W on Low and causes the choke winding [57A cable] and the primary windings, same cable, to get quite warm very quickly. Running at 1.5kw on High for 10 minutes only causes a slight warming of the 57A cable, the choke cores are cold and the secondary of the transformer appears to be cool. But 800 Watts from that crap waveform really heated up the 57A winding very quickly. So 51uH choke, heat gun high @ 1.5kW  HI/LO drive to transformer.  800W of crap from Low Heat gun setting. Sorry for poor focus, dam camera.  The HI/LO drive is not quite as bad as I thought, but there is concern there if the CRO got this correctly.  . It's all too hard. Mike. |
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wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1156 |
Our Panasonic inverter microwave does play with one of our our wifi connected (2.4GHz) televisions if it is streaming content from our wifi modem. The microwave is roughly half-way between the devices which are about 20 metres apart. When the microwave starts, within a few seconds we get the spinning icon on the TV screen associated with buffering issues, when the microwave stops the program continues again after a short pause. But I personally believe that the "inverter" microwave is just getting a bad rap and it is actually just the RF side of the Magnetron which is typically 2450 MHz (2.45GHz) causing the issue, but I dont have a normal microwave hanging around to prove it. I assume The Microwave energy must leak enough signal to affect an already poor s/n ratio for the affected TV. Have not had or noticed any blue tooth issues. If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1024 |
I have been using an old Whirlpool M 595 MICRO, its over 20 years running here, no problem for any inverter, think its 1200w-1500w, heating power 850w rated, used about 6 times a day every day, mostly just reheat as the coffee machine Doesn't get hot enough, no intention of getting an inverter type until this one or the spare one blow's up. As for the crap sine wave caused by the heat gun on low (and some other appliances) I'm more concerned about what other house hold appliances could be damaged from this long term use. Some time back I used the big 50Amp rectifier to do a battery charge from the generator, no problems until I could here this loud buzzing sound from the big split system Air-con, it was not in use but the power was still connected to the unit, The loud buzzing was the line filter inside the air-con, trying to filter the horrible sine wave that was produced by the battery charger running. Cheers Aaron Off The Grid |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679 |
Hi Mike, we posted at the same time a few posts back, wondering if you have any thoughts on the the waveforms, concerns? Yes, as you say, it would only take a small amount signal to cause a problem, maybe from around the power lead filter etc. Before someone gives a safety talk, I'm sure everyone here is aware of the dangers of microwave RF leaking around the door cavity trap and seals from thing like food and liquid build up Aaron, that's another thing I had not thought of. Other sensitive equipment trying to filter this crap and heating their EMI filters, guess it depends how far and what's in between them and the source of the garbage on the mains feed. BTW All my parts from LSCS arrived just now . It's all too hard. Mike. |
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| wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1156 |
I dont have a lot of time right now to do this subject justice but I will try to answer concisely. When an inverter is idling with no load the sine pwm drive per 180 degrees is symmetrical and output is 240V for arguments sake. Now present a 2.4kW resistive load and the HF PWM peaks have increased their on time drive as required to overcome unavoidable circuit losses and the higher load. Now lets put the same 2.4kW load with a half wave rectifier in series with the load - I am assuming a predominately resistive load, not a complex load for the moment. For half the sine wave the sine PWM drive has increased for the losses for the conducting half of the sine. But the other half of the sine is unloaded and in my mind as the HFPWM drive is now greater than that required for true symmetry for the remaining unloaded half sine, the result in my mind will cause the flux to continue to ratchet up, in the direction of the unloaded half sine. I believe the end result is a mixture of some toroidal core saturation and the servo loop for stable voltage comprimising drive to maintain the original 240V. Again in my mind this is why the lower half wave power required actually causes more wiring heating than a balanced load. I dont have the time to emulate/prove/disprove my theory but a current probe should assist in the investigation. Of course a flux monitor in the toroid would be priceless. I do have some analog hall sensors and have often thought about a saw cut in the toroid and inserting a sensor to finally reveal the inner workings of the inverter toroids. Glad to hear your bits have finally arrived. An after thought, if using an unfiltered feedback to the EG8010 - it is happy to see a feedback sinewave level, I suspect swapping the A & N would be worse one way than the other. Th EG8010 only samples the VFB once every 360 degrees. I predict a rectified filtered feedback could be the worst type for the EG8010 as it is much slower to respond to load changes - just a theory. Edited 2023-01-20 14:46 by wiseguy If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679 |
 It's all too hard. Mike. |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679 |
I have not been using an AC output filter in bench testing. I have two 7A mains filters from the aerosharp (I think) and an EMI filter also from the 3kW Aerosharp, looks like it's from the mains in? Very thick wire with dual stage toriods, 0.22uF across the AC in, 2 x 0.01uf to ground between the input and output toriods, and 0.47uF across the AC out. I wanted to see how much difference this made to the part rectified waveform produced by the crap Heat Gun on Low. First I tried one of the sealed 7A mains filters and it made some difference. DC input current on the crap waveform went from 19.5A to 17.8A and the waveform on the CRO was better, the Primary waveform had far less ringing envelope around the large kink in the sinewave I then tried the big dual filter, the DC current went down to 14A and the waveforms looked even better, it's a waveform I could live with. The Heat gun is rated @ 240V 1.6kW / 800 Watt and I'm running it on 220V. The crap waveform is caused by a Diode in series with the heating element for low power. DC input no filter: 1.5 kW on High 1000 Watts on Low It's supposed to be half power on low. With the Filter: 1.5 kW on High 753 Watts on Low. So the filter removed 250 watts of heat from the Inverter driving the Heat gun on low. Current draw is almost normal.   . It's all too hard. Mike. |
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| wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1156 |
Mike, that is a rather amazing result & quite unexpected. Given that they are just usually an overgrown common mode choke and capacitor set up I am at a bit of a loss to explain how it could improve the half wave loading so much. But I have a couple of questions, was the AC feedback for voltage control before or after the filters - if I had to guess I would guess maybe after. There is an extra 0.75uF across the mains is it possible that may be more the reason for the improved current ? Although not fitted yet I also have the same filter that I had intended to employ in my final setup I am looking forward to see what it does with my inverter. If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679 |
I actually did this because of the fact that it's the distortion created by the load reflecting back into the transformer and I know it's nothing to do with PWM. Why? because my High voltage inverter does not suffer from this, and it uses virtually the same EG002 board. The big thing missing is the Transformer. The AC feedback is always connected right at the secondary winding of the transformer and the secondary CAP is across the same connection point. So I though, what can I do the take the edge of that distorted waveform, I thought a double EMI filter may help knock some off the HI frequency transients, if it does, then it warrants more work on the type and construction of EMI filter I use with a view to doing more than just limit the EMI, but also precondition the transformer secondary connection to the nasty outside world. The extra 0.75uf makes zero difference. I tried that again yesterday with various incremental values. I wanted to see if using a higher capacitance and lowering the Resonant frequency of the transformer down to 17Hz would remove more of the 20kHz waveform noise, after all, were all talking about the Choke and reflected capacitance filtering this out to a degree, but NO, it did nothing and it increased the effects of the Heat gun???? So, is this another one of those contribution reasons why some inverters on the edge go bang, and others don't? BTW just tested the Band Saw again with all changes, 229 Amps on start, almost 12kW and allowing for the voltage to sag really low, which they don't, even at 400A on 24V. I have 1m of ZERO gauge between the batteries and the DC input on the inverter board and only a 480A DC switch in between for testing. . Edited 2023-01-24 12:55 by KeepIS It's all too hard. Mike. |
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