Aw poo, now I just gotta know how sine my EATON UPS really is too, they really should be forced to include waveforms for all inverter equipment in the manuals / documentation. It would be sweet to know if you got that pure sine or pure sin wave inverter! Seems good a reason as any to actually buy a scope tho right, right?!
Power should not be thought about except for the that are clinically compulsive, rich, brilliant and willing to spend their lives getting mostly nothing accomplished.
Plug a desk lamp into it. If it sounds buzzy it a square or modified wave, if it sounds normal it's probably a pure/true wave. What AvE said about it being impossible to create a proper wave with an inverter is incorrect, my MicroSolar puts out a very clean wave.
Speaker and 12k ohm 1w resistor would tell you, just don't plug it for too long, 5w speaker minimum. You can clearly distinguish square wave triangle and sine wave. There are apps on phone that can generate these sounds for comparison.
A hunting joke, you say? Okay: An old man was at his doctor getting a checkup. The doc asked him, "So, how you doing, pops?" The geezer smiled and replied, "I'm 92 years old. I've never felt better! Six months ago, I married a smoking hot 30-year-old blonde, and guess what? She's pregnant with our son, who will arrive in two months! What do you think about THEM apples?" The doctor thought for a moment, and said, "That reminds me of a really great story. I have a pal who loves hunting. He loves it so much that it's an obsession for him. So much so that this fall on opening day, he was so excited to go hunting that instead of grabbing his rifle on the way out the door, he grabbed his umbrella. Well, he was quietly approaching a small creek, and not 10 yards in front of him he saw the biggest, fattest beaver he had ever seen. It had to be some kind of record! So he raised up his umbrella, took dead aim, and...BANG! The beaver fell dead where he was standing." "Wait one second," said the old man, shaking his fist, "somebody ELSE must've shot that beaver." The doctor nodded and replied, "exactly."
Nodding knowingly all during the sermon. Walks away with the group. Tim - "Bob, you understand any o'that?" Bob - "Not a damn thing, Tim. Wanna nother beer, eh?"
After watching this channel for maybe a year I was really lost in a lot of this electrical stuff. Still really interested in content though because of curiosity. It’s all coming together now, 3 weeks into HVAC-R tech. degree and intro to electrical theory. AMAZING revelation. Trying to edify AVE here in the impact this channel has and will continue to impact my trade education. First time chiming in here but just wanted to say thx. Been mooching long enough and obligated to contribute to patron. Thx Again AVE
"Modified sine wave" is complete marketing BS, "Modified SQUARE wave" is the correct terminology, but marketing heard that "sine wave is better" so they changed it to "modified sine wave"...
more expensive inverters/rectifiers have a lot better filtering and PWM to get much much closer to a legit sine wave. Used to work on big (like multi MW) UPS systems and DC plants, and once you start spending the big bucks you get really accurate power reproduction. thats why they get to keep the name sadly
viermidebutura The dead time is what makes modified sine wave “modified”. The reason for the dead time is to avoid the extreme transition, and momentary near short, of a true simple square wave drive plus it creates an actual zero crossover reference period. Modified sine wave is much, much, gentler on inductive loads, such as motors and transformers, than the even simpler pure square wave of much older early AC inverters as it the magnetic field to collapse more gracefully before the polarity transition occurs which allows those loads to both run much cooler and generate fewer harmonics versus simple square wave. That said, I think we would all likely agree that it really should be marketed as “MODIFIED SQUARE wave” but then that would be bad marketing wank since consumers have learned to look for the words “sine wave” if they wanted a “better” inverter - its like calling a battery “marine deep cycle” even though the battery is most certainly not deep cycle but uneducated consumers trust that a battery that says “deep cycle” must be deep cycle. Many modern inverters of this type will also vary the output duty cycle to help soft-start heavier loads, like motors, that would often overload the earlier square wave AC inverters. Had this been a real “pure sine wave” AC inverter the output would have been Pulse Width Modulated at a much higher frequency (somewhere in the range of 20-100KHz) that would then be smoothed by a low-pass filter to form a proper sine wave output (essentially they operate as a Class D amplifier).
Im not surprised that the waveform looked like that. The inverter you tested doesnt claim to be a pure sine inverter. Its working exactly as advertised.
That's a modified sine wave inverter, if they are pure sine they usually either have it written and/or have a sine wave symbol on the case. Would be nice to see you examine a pure sine wave type.
I love your video's and the way you explain this stuff. I try and come here daily for some stress relief! Thank you, and please do not stop doing this.
I happen to be working at a company that sells and repairs UPS units (big ones, up to 500 kVA), so I have seen an inverter or two over the past few years. That poor thing on your healing bench is a joke from the technical point of view. The only admirable thing about it would be how the design was cost-optimized to death when it actually still works without setting everyone you love on fire, but that's about it. The machines we work with acutally do generate perfectly clean sine wave (regardless of the brand, it's a trait of the class). They usually have a very beefy brainboxes, utilizing FPGAs for precise MOSFET/IGBT control and use very high frequency PWM to "draw" a hi-res approximation of the sine wave, which is then fed through an output low-pass filter to iron out the noise and distortion with as little power loss as possible. Some devices can go under 1% output THD with linear load and under 3% with non-linear load, which is usually way better than the input power from the grid. The cost, of course, is a different story. My point is that you actually can generate a clean sine wave using solid-state switching converter although a lot of engineering needs to be involved.
"fed through an output low-pass filter" Yeah, when he was talking about a perfect sine wave being impossible from switching, I was thinking about output filters and Nyquist's theorem and such.
Taking a guess at the architecture, the first stage looks to be a push-pull step up convertor, with a passive output rectifier (all those diodes) to generate an DC link at 170Vdc, from 12v to 170 is about a 14x step up, which looks about the winding ratio on the primary inductor. Then that DC link is sent through a basic 120Hz 3 step output (ON - OFF - ON (reversed polarity) to generate a square wave output. When you switch on the grinder you can see it increase the ontime to attempt to keep the RMS voltage at the setpoint (120V), which of course further distorts the waveform into something like looks more like 2 steps. 2kW is 16.6A at 120V, so the output stage, which only switches slowly (and therefore has little switching losses) is fairly small. The input stage of course, down at 12Vdc, needs to pull 166Amps (plus loses) so is a lot more beefy. Even with 8 fets, that's still over 20A per Fet. Because of the high current, they use N channel Fets to get a sufficiently low RDSon, and therefore have to use an isolated source referenced gate driver to create suitable gate voltages (probably at around 24V (12Vsupply + 12V gate)
I was going to buy a scope, and then got a USB all-in-one scope/power supply/waveform generator called an Analog Discovery II. It has been the greatest thing I've ever bought for electronics hobby work. Would recommend. Unfortunately, the 25 MHz bandwidth is probably to slow for a lot of radio frequency work (I don't know anything about HAM specifically).
Thank you!! I've been dying to see something like this. I'm an OTR trucker and I rely on a 1500w inverter to power stuff like a skillet, 700w microwave, grooming stuff, laptop, etc. And I won't lie, it's a piece of chit!
Definitely not a "true sine" inverter. Did you mean to say it that way at the start of the video? True sine inverters exist (I have several) and they put out a beautiful sine wave. Cleaner than the utility mains by far.
Almost a million subs, holy shit. I've been here since about 200-250k. RU-vid unsubscribed me automatically(I don't know why) but I knew it right away. I'm surprised this channel is still here.
I salvaged the controller out of an old California Instruments "Invertron" that got scrapped at the electric motor manufacturer where I used to work. Interesting little thing. It had an 8 bit ROM chip that could code up to 256 levels of output, and they coded a quarter sine wave into it. A four stage counter would step output modes every time the address in the ROM hit either 11111111 or 00000000. When it hit all ones, it would reverse the address counter and count back down from 11111111 to 00000000. When it hit all zeros, it would again, reverse the address counter, but also toggle the output polarity. This gave a 512 level digital sine wave that completed one cycle in 1024 total steps. Not too shabby for a bit of kit from 1980!
That kind of waveform will kill AC induction motors such as found in refrigerators, electric fans and such, they will dissipate much more power as heat due to the high harmonic content. Powertools generally don't mind because they have a universal motor (which is actually a DC motor which also doesn't mind running on AC) but will run a little hotter because of the eddy currents induced by the high frequency components of the wave. In most electronic devices the input filter capacitor gets ruined rather quickly as it cannot handle the sharp rising edges of the boxy 'sinewave'. The device will still work but it will leak noise into the mains supply and will also become more vulnerable to switching spikes in the mains supply which could cause unexpected resets, data corruption and stuff like that. Devices that use a capacitive divider will probably die after a few minutes but I've never tried that. I mean things like plug in digital timers, remote controlled socket outlets and such. Good quality inverters do exist that actually produce clean sinewave outputs which are visually indistinguishable from what you get out of a power outlet. They work pretty much like class D audio amplifiers changing the duty cycle of a very high frequency inverter making the output voltage follow an exact sinewave once the high frequency is filtered out by an LC filter in the output stage. Such inverters are common in the better computer UPSs as well. They usually cost about five to ten times as much as the ordinary ones. They are more expensive because they need to run at a much higher PWM frequency, typically somewhere between 150 and 500kHz as opposed to around 5 to 10kHz probably being used in the inverter you got. The cost is mostly in the MOSFETs and the freewheeling diodes.
Many large inverters invert the raw DC bus voltage of rectified mains using hundreds of tiny steps with little to no filtering required, the tried and tested method of most massive online based UPS's in large datacenters to generate 3 phase AC with a string of SLA batteries and very large IGBT's.
I used to work on 400Hz converters when I was in the navy. They make nice clean sinusoidal waves. Kind of neat seeing it broken down in to a smaller scale.
Where did you get such an impressive skill set? This guy is very smart. I personally am a millennial and let me just say true Technicians and mechanics are a thing of the past and this guy is one of the last of a dying breed. Cheers buddy here’s to you!
Love when you do electrical stuff. I'm an I/E tech, and even though I'm mainly Instrument I started as a pure electrician and love the electrical theory.
Really glad your covering this topic .... I’m about to put power in my truck ,, need to run electric Jetter and sewer machine lights etc... at same time
I'll send you the wave form I get out of my Trace 2548 inverter, its impressive how many steps there are in a wave. Of course you pay out the nose for that, but I was running a lot of computers of it in the late 90's with a train battery. Wish they were in business and still made. My first one was a 2512, but the 00 battery cables would dance under load, I could calculate somewhere in the neighborhood of 400A pulsed DC draw. Like watching tassels spinning at the titty bar and almost as fun.
@@newdeathscope server farm, and I may be able to find pictures, this was ~97 I set it up. Full flege ISP with national DSL service completely independent backhaual.
Many years back I did one of these of my own design. It got very close to a sine wave and was quite efficient. The primary side is fairly simple because it just made nearly a square wave on the transformer windings are 100KHz. The secondary side was where the bulk of the magic lived. Basically: If the MOSFETs on the output were in step with the ones on the input you got +170V If the MOSFETs on the output were out by 180 degrees you got -170V out At 90 degrees the output was 0V almost exactly. Some electronics wobbled the phase at a 60Hz rate.
Awesome I am excited to watch this after work I took apart a converter from an rv a little while ago there's some interesting circuitry in those thing too if your intrested in doing a tare down of one let me known I have piles of them
I’ve been repairing stuff like this for over 3 years and this did make me giggle, from a drunken glance, that was modified sine wave and the general rule of thumb is if you’re using an inductive load (heaters, microwaves ect) your load will be double what it’s rated. ^^ SINGLE SIDE PCB’S MAKE ME CRY
The input configuration is a push-pull. A transformer coupled push-pull to be precise. The current goes through the bank of fuses to the two sets of thick black wires soldered into to the board. From there it goes through the torrid once in either the left or right direction depending on which set of four MOSFETs is on. Finally, it returns to ground. Do a google search for ‘push pull inverter’ for lots of examples. The output might be an H bridge. Love the 'sign wave'
Connecting vehicle mounted inverters I use a test light in series to one input lead to bring it up to 12v slowly through the test light to avoid the lightning arc on the terminal. Conversely when disconnecting I use it across the input leads to discharge the thing to avoid the 12v leads arcing if they touch while removing it.
Your videos are one of the few reasons I’m sticking with the nuclear engineering path I want to pursue. My math skills are gettin steadily better. Hopefully I’ll be doing calculus fluently in a year or two.
What a great day to leave work a little early, didn't even know Uncle B had a new vijayo - but damn if that's not the first thing I'm doing with this time!
That's a modified sine wave inverter you can get pure sine wave inverters that do show a proper sine wave on the scope, I have one and the power output is very clean.
That inverter says it is modified sine right in the item description. A pure sine or true sine inverter will put out a very close approximation to a perfect sine wave. In fact, many of the quality pure sine inverters can put out a smoother waveform than you sometimes receive from the utility grid. These days it almost doesn't pay to buy a modified sine inverter because the pure sine inverters have really come down in price.
Boom says Hi....All that smoketalk in the beginning,Congratulations On Freeing up Refa Canada!,,Great teacher for sure.Electronics has been weak for me,You bring into perspective very well.73s
Remember doing a tour of BC Hydros VIT (Vancouver Island Terminal) in North Cowichan near the end of our 4th yr ElectChickin training (1977). There is an under water (and also a ‘sea link’ negative return!) 330kV DC cable link to the Delta terminal that changes the DC pixies back to the AC. (That I believe is now an ‘emerg’ back up to the 500 kV AC line across to the island) They had MASSIVE mercury arc thyristors to create the AC pulse and then a couple of 1Mw synchronis rotary condensers running in a pressurized hydrogen atmosphere (!!!) to ‘smooth’ out the wave (and could also ‘adjust’ the frequency averaged to 60 hz over a 24 hr period by playing with the excitation) All the while, thinking that it was a halloween setup or something from Dr Frankenstein. They had experimented with using massive banks of 200 amp rated SCR’s as the maintenance on the mercury’s arc thyristors was costing a fortune... last I heard, that only increased the speed of getting the 500 kV AC transmission line completed down from the WhackyBennet dam. Pretty sure Kanuckistan Tyre wouldn’t go to all that trouble! Always a pleasure to watch you thinking out loud while also engaging your safety squints.
Looks to me like you were right about the output power stage - it is an H-Bridge. The input side is a push pull configuration (note that one end of the windings are connected to batt +)
Unbelievable Ave, its like you read my mind or something. I had what i thought was a good inverter, but hadn't tried it yet. And the other day i had it hooked to just a dam fan , and as you would say she let the smoke(not a pleasant smell) out after about an hour. So i disassembled, and im sittin here and your doin surgury on a very similar one. Mine had 4 or 5 blown mosfets, but i wanted to fix it. So that was very helpful. Kudos I wonder if the mosfets were all the damage though? If thats it (I HAVE THE POWER!) And a new desolering gun,will travel. Lol
When you were on the boat you used the blender to get the coffee maker to work. Once the coffee maker turned on could you then turn off the blender as the impedence from the coffee machine could provide the same impedence?
MOSFETs will typically fail into a closed circuit state and then send power out the gate which the lower voltage electronics love. IGBTs which are common in other inverters/converters like VFDs will normally fail open but have much higher losses when used in low voltage applications.
My old man is his retired boredom decided to rewire the house with a bank of car batteries running through a 'sine' wave inverter. Despite the advice of two energy enginerds to use proper switching, or better yet, to do something actually useful, he didn't isolate the inverter properly and put the 240v mains voltage into the 24v DC input. It had 24 of those car fuses, 12 were blown, and all of its huge capacitors were ruptured. I was informed that he was sure it would be easy for me to fix it :)
The interesting thing is that, these kind of inverters already have a stable high voltage power supply, and usually a driver bridge at the end that generates the fake sine wave similar to class D amplifiers driving bridge. If they have added a relatively low frequency PWM generator driving the bridge at lets say 5kHz, and added a simple low-pass filter made from a single coil and capacitor to filter out the driving frequency they could produce almost perfect low frequency sine waves (50-60Hz) with very high efficiency. It is just not needed in the most cases. But if it was needed, it could be made for a little more price.
What do you mean? Class D amplifiers work exactly the same as this inverter, it is just switching the mosfets on/off, thats the most efficient way to reduce power dissipation, therfore minimizing power loss. The only difference is, you dont just simply turn them on/off in a square waveform, but you modulate the width of the squares, to create sine. Btw if you use igbt mosfets for switching at the end (and you can, since the voltage isn't extremely high and the frequency is low) you can increase the efficiency even more. Especially if you make ZVS switching for the power supply area.
I've built a class D, and I believe the coil cost me around 5 bucks. Which is really expensive for these kinds of electronics, which is probably why they didn't bother. Lot of copper needed for high current.
Reminds me of 6 step output of older industrial VFD's before everyone started using PWM. Older drives were much easier on bearings than the new pwm output but components had to be much larger.
I get the 2 banks with fans and black wires through the toroid as pulsing the DC to get AC on the thinner wire on the toroid. However, what does the third fan and FETS do on that 3rd aluminum block?
mosfets fail open?? I rarely see that in the amplifiers I repair... unless by open, you mean they open after they sit shorted and get hot enough to blow apart?
i just did the goof he talked about with our 750w inverter it got the 4-25a fuses. soldered a wire to test and it fired back up so i guess i will pick up some 25a fuses and resolder them in
In my experience disassembling stuff factories usually use N-Channel Mosfets for Half or Full H-Bridges along a floating gate driver to save in costs as N-Channel mosfets cost much less for the same current capability than P Channel ones so the driver will have a charge pump dc-dc to boost it to say 36V and so you can drive the lower mosfet with 12V and the upper one with 24 or something like that so that the lower one has 12-0=12V between the gate and source and the upper one has 24-12=12V between its gate and source. :P
Totally a modified sine inverter, but they didn't call it a pure sine, they said "digital" right? Maybe I missed it, but it looks like a piece of chit! Doesn't look reliable at allllll, just enough for a few computer charges in a power outage, and will probably blow up after your 2nd cup of coffee, haha.
No real need for this, harmonics of "modified sine wave" are well known. If any waveform have the same positive and negative pulses (not like positive is longer, but smaller amplitude, anything like that) then signal has no even harmonics at all! So we're down to 1, 3, 5, 7, 9 etc. The simplest square wave without pauses have amplitudes of these proportional to 1, 1/3, 1/5, 1/7 and so on and so forth, with phase shift of 180° from one to another (or say: it's constantly changing sign). When there is pause present, some of harmonics could be eliminated. Best case would be when duration of each pause is 1/2 of each pulse. This way we eliminate 3rd harmonic and all multiples of it: 6th (but it wasn't here to begin with), 9th, 12th (was'nt here either), 15th and so on. So waveform like this is pretty easy to filter out, as the most annoying would be 5th harmonic, 300 Hz. But we see: duration of pulse changes to accomodate for voltage drop on battery which leads to lower amplitude of pulses on output. So when grinder is turned on, "brainbox" reduces duration of pause, so rms would be still 120 V.
I was ready to walk when I saw paralleled fuses and diode - probably unmatched to boot. At full load that's 220+ amps draw on the battery at 90% efficiency. I hadn't thought of the pulse effects on the batteries - thanks! This would need an output 1:1 20 amp transformer to get a fairly clean regulated output.
Nice one review, I would love for you to do a review on an APC inverter in a UPS, pretty cheap even for the good models, but they claim to be much better and given that they are battery and inverter in one, much easier to test.
@AvE In a mob: Pixies don't care and move as a mass. When pixies are singled out and put in a slow line; they tend to be very sensitive and needy to keep them on the proper path. This is how I have seen it to be =)
They use bootstrap circuits for that: very cheap and effective. Capacitor is charged to some 12 volts when lower switch is on. Then capacitor is commutated between source and gate of high-side mosfet, so it turns on. Voltages on both plates of capacitors rise quickly up to rail voltage, but it's no problem. Voltage across is still the same.
If you happen to get hold of one of those dewalt 1800 inverters it would be great to see it on the scope. It will run my 110v mig welder but the welder definatly sounds different. Thanks for the video!
When i had that inverter, the jeeseless thing only put out about 90vac. It got returned and i got a pair of inverters that make 105vac instead. Never regretted that decision.
If you put this modified square wave thru a isolating transformer(120v-120v) is the output of the transformer any better? is the least power waste (blender vs magnetization current of the transformer) considering running for long time of battery.
This video taught me a lot about inverters! I have one in my work van, I am a small engine mechanic. Every time I hook a snow blower electric starter to it thing fucking spits some charger then stalls, try again spits a little and stalls. Turned off my pancake compressor and she chooched just fine. Quality product size of a bowling ball, made of aluminum, but I guess she has her limitations.
One logical reason for them not putting reverse polarity protection on those things (because even the good ones don't even have it), is that an input diode would create a 0,7 volt voltage drop and on a 12V nominal battery system, it's an enormous deal. It's the assumption I've always went with.
Fred Laroche In setups like this the input protection diode is typically reverse biased across the positive and negative rails such that on a reverse polarity event the pass-through voltage is clamped to below 1V and the diode(s) place a dead short on the power rail to blow the fuses quickly. However, the diodes are also frequently damaged and require replacement afterwards since the diode(s) often fail short-circuit. This reverse biased setup avoids the 0.7-1.0V diode drop under normal operation.
Put a old fashioned incandescent test light in series with the inverter before you connect it. The lamp will act as a resistor and prevent the surge of current that creates the spark. You can watch the capacitors charge via how bright the lamp is lit. It will be bright at first and dim until it goes out completely, indicating the caps are fairly well charged. Then I connect it directly.
That's a modified sine wave inverter. They great for running incandescent lights and power tools with universal motors, but they like to burn up induction motors and transformers. They are not particularly good for switchmode power supplies either. A true sine wave inverter will produce a waveform almost identical to what you get out of the wall socket. They cost several times more than a modified sine wave inverter though.
Cheap inverter generators produce almost as near as good pure sine wave, they use a pair of toroidal inductors to do it however this design doesn't scale very well, where the design in the video scales significantly better, however it just looks to employ a massive DC boost converter and then chops up that HV that is also tanked in the 2 larger caps at the bottom. Units that have a lot of steps that employ a similar output inverter that gets a perfect pure sine wave also do this because it eliminates the need for a massive transformer to smoothen the output thus it scales about endlessly, you commonly see such designs in massive online datacenter UPS units and of course this is considerably more expensive. You can get a very good sine wave out of an APC SmartUPS too however this design uses a large heavy transformer for the output (and runs in reverse to charge the batteries).
In addition to that the cheaper ways of generating perfect AC sinewaves with a good amount of usable power require a HV bipolar DC input or an AC input to generate the said bipolar supply, such as from a generator stator. The DC-DC converters to generate those supplies from 12V would also be cost prohibitive.
There's a skookum choochin invertar laying on the shelf at work, bigger maybe than the unit he tore a part but only 300 watts. Was wired up with 4ga fine strand, Anderson connectors and proper fusing. defiantly I would chuck it north to see it tore apart for tits and pickles. cant recall the name but white body blue print all METAL and cert output sign off when packed.
You got that right...back in 1980, I worked for a made-in-USA company that had to build some equipment to operate in Saudi Arabia, which at that time used 50 hertz, the equipment had induction motors among some 'newfangled' microprocessors (4004) running from an antique transformer type power supply... We shared Mfg. shop with a high end audio amplifier company....so we used a signal generator and a 5KW amplifier to run the equipment...worked out fine.... More recently, in 2010....my last employer had a very expensive high end Motorhome with a 2.5KW inverter...about 3 times the size of this, was also a battery charger running from 120 VAC 'shore power' to charge 2 BIG AGM batteries at 12 volts, 150 amps...it had a 2.5KVA power transformer with 120 output for the motorhome 120 VAC receptacles... The big transformer was used for both inverter and battery charging.....several very large heat sinks and banks of Mos-Fets...I don't recall the name of Manufacturer, but it was very expensive, something like $5,000....
I've got an old Elgar UPS that uses a 16-level sine wave approximation. By the time the pixies come out of the massive transformer in the center of the beast, they behave like a real sine wave. It's rated at 1.4KVA and lifting it will pop those hernia stitches.
Do you have a recommended inverter that is robust, but wont break the bank and has a clean output? Im wanting to install one that could handle a small pancake compressor in the truck, or handle a skill saw and such connected to it.
I typically turn motion stabilization off on the camera when using it on a tripod.. But that won't fix the problem of the new space being uncomfortably clean!
