Google Little Box Inverter Winner - Page 1
Forum section: electronics / projects

author: theoldwizard1
author_rank: Regular Contributor
timestamp: March 16, 2016, 02:25:38 pm
content: A group from CE&T called Red Electrical Devils has won $1M from Google by designing a DC-AC inverter with extremely high power density (143 W/in³).This is a >2kVA with a maximum enclosure temperature of 48°C, 400V DC (input), 240Vac split phase output.Some of thekeys to their successwere using GaN power semiconductors and "... control(ing) all the GaN transistors using soft switching for the entire operation range."QuoteThe portion of the circuit shown in the link only contains the "drive" section of the inverter.Now much of those conclusion is probably beyond the scope of this forum, butI would certainly like to understand more about "using soft switching for the entire operation range" and how it can improve efficiency on SMPS.

author: zapta
author_rank: Super Contributor
timestamp: March 16, 2016, 03:16:05 pm
content: Any estimation what is the component cost?

author: elgonzo
author_rank: Unknown
timestamp: March 16, 2016, 03:30:25 pm
content: Oy. Somehow the link is screwed.

author: theoldwizard1
author_rank: Regular Contributor
timestamp: March 16, 2016, 05:08:07 pm
content: Quote from: elgonzo on March 16, 2016, 03:30:25 pmLink fixed

author: rx8pilot
author_rank: Super Contributor
timestamp: March 16, 2016, 05:15:05 pm
content: Quote from: zapta on March 16, 2016, 03:16:05 pmAt this time, GaN is not cheap. I am working on an SMPS design using 4 eGaN devices that are about $11/ea and require special gate drivers on top of that. It does really help with density though which is what I am after.

author: theoldwizard1
author_rank: Regular Contributor
timestamp: March 16, 2016, 08:48:05 pm
content: Quote from: rx8pilot on March 16, 2016, 05:15:05 pmI have been retired for 8 years so I am "out of the loop", but quickly looking at some specs an GaN devices their Ronisn't that much better than the best MOSFETS.What other advantages do they have ?

author: rx8pilot
author_rank: Super Contributor
timestamp: March 16, 2016, 10:37:03 pm
content: The GaN promises very low switching losses that are a result of Qg, Qrr and other parameters including low-inductance packages. The result is very fast switching compared to Si to actually take advantage of the Rds(on). The fast switching allows the magnetics and capacitors to be much smaller - my silicon solution is 500 Khz and the GaN solution is around 2Mhz. The end of the day efficiency is not expected to be much different, but the size will shrink considerably. Running a high current switcher at 2Mhz with Si devices would have poor efficiency.

author: theoldwizard1
author_rank: Regular Contributor
timestamp: March 17, 2016, 01:16:15 am
content: Quote from: rx8pilot on March 16, 2016, 10:37:03 pmSo if extremely small package size is not an issue, you can "come close" to the same efficiency with "traditional" MOFETs and drivers and keeping the switching frequency <500Khz.Looks like GaN is going to be a niche market for awhile.Now how about some insight for us about using "soft switching for the entire operation range."

author: JohnG
author_rank: Frequent Contributor
timestamp: March 17, 2016, 05:53:03 pm
content: Quote from: theoldwizard1 on March 17, 2016, 01:16:15 amOr, you can run at the same frequency, keep the same size, and cut your losses by 30-60%. Going from 94% efficiency to 97% doesn't seem like a lot, but it means cutting losses in half. This could mean elimination of a fan or a heat sink.John

author: rx8pilot
author_rank: Super Contributor
timestamp: March 17, 2016, 06:02:02 pm
content: Quote from: JohnG on March 17, 2016, 05:53:03 pm

author: JohnG
author_rank: Frequent Contributor
timestamp: March 17, 2016, 11:28:00 pm
content: Quote from: rx8pilot on March 17, 2016, 06:02:02 pmI'm betting my career on it, so I'm doing what I can to make it so.

author: rx8pilot
author_rank: Super Contributor
timestamp: March 17, 2016, 11:33:51 pm
content: Me too. Hopefully I am a few minutes ahead of the curve for once.Sent from my horrible mobile....

author: EEVblog
author_rank: Unknown
timestamp: March 18, 2016, 12:06:10 am
content: Gotta be the guy with the funky white hairYep, he looks like the lead:

author: JohnG
author_rank: Frequent Contributor
timestamp: March 18, 2016, 03:26:22 am
content: I will be at APEC (Applied Power Electronics Conference) next week, and rumor has it that the actual inverter will be at the GaN Systems booth. I'll look for it and see if I can get a picture, maybe with a ruler or similar.John

author: rx8pilot
author_rank: Super Contributor
timestamp: March 18, 2016, 03:44:51 am
content: I will be there too. We should say hello.Sent from my horrible mobile....

author: coppice
author_rank: Super Contributor
timestamp: March 18, 2016, 04:06:33 am
content: Quote from: theoldwizard1 on March 17, 2016, 01:16:15 amI don't know anyone working on GaN that has small scale plans for it.

author: JohnG
author_rank: Frequent Contributor
timestamp: March 25, 2016, 04:22:28 pm
content: Some pictures. Sorry I could not get a ruler in the picture. About the size of two packs of cigarettes (100s).

author: theoldwizard1
author_rank: Regular Contributor
timestamp: March 25, 2016, 05:34:25 pm
content: Quote from: JohnG on March 25, 2016, 04:22:28 pmI assume the extra 2 wires are for switching high side and low side the transistors on.What about feedback for the Class D amplifier to know when to turn off the signal or are they just tapping off of the output wires ?

author: JohnG
author_rank: Frequent Contributor
timestamp: March 25, 2016, 08:59:21 pm
content: The extra orange wires are for a remote enable. Everything else is contained in the box, including all control, feedback, etc.The DC in and AC out are supposed to be fully filtered. You can find the target specs here:https://www.littleboxchallenge.com/pdf/LBC-InverterRequirements-20141216.pdf

author: theoldwizard1
author_rank: Regular Contributor
timestamp: March 26, 2016, 03:38:09 am
content: Quote from: JohnG on March 25, 2016, 08:59:21 pmInteresting that Anderson Power Pole connectors are actually called out in the spec !

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 26, 2016, 03:58:24 am
content: Hard to judge exact size with those pictures alone, but I have seen a 1kW inverter that's about the size of two stacked decks of cards. It was being used in a DIY hybrid bicycle. Most of the space was occupied with capacitors, with a few TO220 MOSFETs on one side bolted to the aluminum case that acts as a heatsink. A C2000 processor handles the control.EDIT: Is that unit isolated or not? That would make a very big difference in the "impressive factor". The bicycle inverter obviously isn't.

author: diyaudio
author_rank: Frequent Contributor
timestamp: March 26, 2016, 10:56:31 am
content: Quote from: theoldwizard1 on March 16, 2016, 02:25:38 pmAnyone know if this project will be published ? The thermal simulations and models looks very interesting what CAD tool are they using here?

author: PointyOintment
author_rank: Frequent Contributor
timestamp: March 27, 2016, 05:50:25 pm
content: Quote from: diyaudio on March 26, 2016, 10:56:31 amClick on the words "keys to their success" in the post you just quoted…

author: theoldwizard1
author_rank: Regular Contributor
timestamp: April 01, 2016, 03:04:16 pm
content: At a "different" end of the spectrum (low cost inverter) you have to check this out !Assembled 3000W Pure Sine Wave Inverter Board - eBay $79.80 !!http://www.ebay.com/itm/Assembled-3000W-Pure-Sine-Wave-Inverter-Power-Board-Post-Sinewave-Amplifier-/181969357098?hash=item2a5e38092a:g:el0AAOSwk1JWeMYYFeed this thing high voltage DC and you get 220V, 50Hz AC out ! I doubt that it will do 2000W continuous without decent air flow and who knows about a "peak" load of 3000W ?(I love the "low buck" temperature sensor "crimped" into the heat sink so it likely has some kind of fan control.)The primary control chip is the EG8010(which will also do 120V, 60Hz with just some jumper changes). It uses some IR2110 drivers and 8 - 47N60 MOSFETS. I think the MOSFETS are really the limiting factor.

author: JohnG
author_rank: Frequent Contributor
timestamp: April 27, 2016, 02:17:08 pm
content: Quote from: NiHaoMike on March 26, 2016, 03:58:24 amThe inverter hear is about the same size, maybe slightly bigger, bu 2 kW. Isolation was not required for the contest, but a lot of other things were required that a bike motor will not need. These include the ability to pass conducted EMI requirements, as well as being able to interface with the AC utility grid safely. Meeting the EMI requirements normally takes a lot of space.John

author: Siwastaja
author_rank: Super Contributor
timestamp: April 27, 2016, 02:28:02 pm
content: Bike "inverter" probably means a (synchronous AC or BLDC) motor drive, which is a completely different project with surprisingly little resemblence to this subject.