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What the inverter needs to do

The winning inverter will be the one that achieves the highest power density and meeting a list of other specifications, as determined by a panel of judges, while undergoing testing for 100 hours.

In brief, the other specifications are :

Must be able to handle up to 2 kVA loads
Must achieve a power density of equal to or greater than 50 W/in3
Must be able to handle loads with power factors from 0.7–1, leading and lagging in an islanded mode
Must be in a rectangular metal enclosure of no more than 40 in3
Will be taking in 450 V DC power in series with a 10 Ω resistor
Must output 240 V, 60 Hz AC single phase power
Must have a total harmonic distortion + noise on both voltage and current of < 5%
Must have an input ripple current of < 20%
Must have an input ripple voltage of < 3%
Must have a DC-AC efficiency of greater than 95%
Must maintain a temperature of no more than 60°C during operation everywhere on the outside of the device that can be touched.
Must conform to Electromagnetic Compliance standards as set out in FCC Part 15 B
Can not use any external source of cooling (e.g. water) other than air
Does not require galvanic isolation

hanelyp wrote:https://www.littleboxchallenge.com/

What the inverter needs to do

The winning inverter will be the one that achieves the highest power density and meeting a list of other specifications, as determined by a panel of judges, while undergoing testing for 100 hours.

In brief, the other specifications are :

Must be able to handle up to 2 kVA loads
Must achieve a power density of equal to or greater than 50 W/in3
Must be able to handle loads with power factors from 0.7–1, leading and lagging in an islanded mode
Must be in a rectangular metal enclosure of no more than 40 in3
Will be taking in 450 V DC power in series with a 10 Ω resistor
Must output 240 V, 60 Hz AC single phase power
Must have a total harmonic distortion + noise on both voltage and current of < 5%
Must have an input ripple current of < 20%
Must have an input ripple voltage of < 3%
Must have a DC-AC efficiency of greater than 95%
Must maintain a temperature of no more than 60°C during operation everywhere on the outside of the device that can be touched.
Must conform to Electromagnetic Compliance standards as set out in FCC Part 15 B
Can not use any external source of cooling (e.g. water) other than air
Does not require galvanic isolation

Interesting challenge. Probably beyond my skills to design myself. The input ripple requirements look like they may be the hard part to meet within the specified volume.

ladajo wrote:I disagree, the harmonic output limitations will likely impede the ability to stay within the stated device volume requirements and still meet power throughput and heat loading.

However, if the switching frequency is high enough the harmonic reqmts. should not be too difficult to meet.

hanelyp wrote:Everything else doesn't look too bad if you ignore the input ripple, just draw power as needed and a low pass filter with a cutoff in the kHz range on output. With the input ripple constraints you need to store a fair amount of energy between peak and trough of the cycle.

ladajo wrote:

However, if the switching frequency is high enough the harmonic reqmts. should not be too difficult to meet.

Nope, disagree again. It will make it worse. Three phase invertors cause a huge amount of harmonic distortion and noise in the output, even using really sexy IGBTs or something better.
The output dampening is going to be a headache to be able to take the heat and fit in the can.

AC does complicate that but the output inductor should help considerably.

ladajo wrote:

AC does complicate that but the output inductor should help considerably.

I take it you are not that familiar with variable frequency invertors.
I do agree on looking for something cleaner than IGBTs. But as you said, it will cost.