Which inverters at https://www.mobile-solarpower.com/inverters.html are transformer inverters?

MurphyGuy

Solar Addict
They all have transformers.. I think what you're asking is which are low frequency vs high frequency.

LF inverters have big honking heavy transformers while HF units have small transformers.

As far as I know, none of the units on that page are LF type.

Also, if they're going to call the Sol-Ark "The King", then the SMA Sunny Island would be classified under "God Status"
 

Delmar

Solar Addict
Easy method to determine LF vs HF transformers: if you can afford the inverter then its high frequency with minimal surge capacity for starting motors. Otherwise 2x oversize a HF inverter to get similar surge capacity to a LF.

Exception is a used industrial UPS which is affordable and has big honking heavy transformers. I have a fetish over APC “XL” models that are pure sine, rated for continuous operation and accept external batteries.
 

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Delmar

Solar Addict
They all have transformers.. I think what you're asking is which are low frequency vs high frequency.

LF inverters have big honking heavy transformers while HF units have small transformers.

As far as I know, none of the units on that page are LF type.
The exact response was "none of the units on that page are LF type".
 

Delmar

Solar Addict
The pictures are deceiving as the units are small. The Victron MultiPlus 3000W unit is 14.3”x10.2”x8.6” and weighs 40 lbs. Data Sheet.

My 2700W UPS weighs around 100 lbs without batteries. Below picture illustrates the size difference with my Reliable 2500W HF inverter.

Edit: the Victron does have larger than usual transformers, however switches at 20khz so cannot be considered LF. YouTube Video
 

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MattiFin

Solar Addict
The pictures are deceiving as the units are small. The Victron MultiPlus 3000W unit is 14.3”x10.2”x8.6” and weighs 40 lbs. Data Sheet.

My 2700W UPS weighs around 100 lbs without batteries. Below picture illustrates the size difference with my Reliable 2500W HF inverter.

Edit: the Victron does have larger than usual transformers, however switches at 20khz so cannot be considered 60hz LF. YouTube Video
What on earth do you consider LF inverter?
AFAIK its the Frequency ”seen” by output transformer.
 

MurphyGuy

Solar Addict
What on earth do you consider LF inverter?
AFAIK its the Frequency ”seen” by output transformer.
SMA Sunny Islands are true low frequency inverters.

They are only a single phase 120 volt output at 6000 watts and each of them weighs 140 lbs. You either need two of them, OR an autoformer to make a 120/240 split phase system.

Magnum also has low freq units as the transformers take up almost half of the space inside the unit.

Very few inverters on the market these days are the low frequency type.
 

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MattiFin

Solar Addict
SMA Sunny Islands are true low frequency inverters.

They are only a single phase 120 volt output at 6000 watts and each of them weighs 140 lbs. You either need two of them, OR an autoformer to make a 120/240 split phase system.

Magnum also has low freq units as the transformers take up almost half of the space inside the unit.

Very few inverters on the market these days are the low frequency type.
So how do the magnum&SMA generate the sine wave?
 

Hedges

I See Electromagnetic Fields!
They would use a PWM circuit running at higher frequency to create pulses of 48VDC, probably with a high-frequency inductor, generating a sine-wave current in the 60 Hz transformer.

The surge capability comes from how much current they can deliver from battery (plus transformer's ability to couple the power.)

I measure much of the current coming from battery as an AC ripple following the 60 Hz output. It isn't steady DC; the capacitors aren't big enough.
This wasn't at a 200% surge, just 40% of full load, but compared to average DC current the actual current swung from approximately 60% to 140%.
 

MattiFin

Solar Addict
They would use a PWM circuit running at higher frequency to create pulses of 48VDC, probably with a high-frequency inductor, generating a sine-wave current in the 60 Hz transformer.

The surge capability comes from how much current they can deliver from battery (plus transformer's ability to couple the power.)

I measure much of the current coming from battery as an AC ripple following the 60 Hz output. It isn't steady DC; the capacitors aren't big enough.
This wasn't at a 200% surge, just 40% of full load, but compared to average DC current the actual current swung from approximately 60% to 140%.
you spoiled my interrogation. :D

PWM frequency is typically somewhere around 20khz (few hunded times higher than 60hz…)

Victron happens to use toroid core transformer that is slighly smaller, more efficient and more expensive than traditional EI-core iron transformer seen in some boat anchors.

Really ANCIENT design could use true 60hz switching and ferroresonant transformer but those are really prehistoric beasts with fair share of problems of their own.
 

MattiFin

Solar Addict
HaldorEE(another EE who has actually designed and built inverters..)has covered the LFvsLF topic pretty well here:
 
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