Axpert King

[Gabriel_2018]

Hi all, I've been watching Axpert King specs and i have one doubt. In this inverter loads can be fed Up by solar, battery and Utility at the same time. Other Voltronic, Infini V can do the same, and also can feed grid, but King can't. Then, I know that in Infini V energy coming from grid doesnt pass trough IGBTs, Max power of load is 4KW from inverter + Grid power.

I suspect in Axpert King is not the same and I think that energy coming from grid pass trough the IGBTs of inverter.

Does anybody Know how King works?

Edited December 14, 2018 by Javi Martínez

[Coulomb]

6 hours ago, Javi Martínez said:

Does anybody Know how King works?

I don't, but I can guess. The "Zero transfer time" claim seems to indicate that, as you speculated, all load power goes through the IGBTs of the inverter. The web page actually mentions servers and Auto Teller Machines as the target market. These models are parallelable, so I suppose if you have a large, unpredictable load (like a household), you just have to have enough machines paralleled to cope with the highest expected load.

So I think that these don't even have transfer relays at all. There must be a power factor corrected rectifier to turn mains AC into DC for the "power bus". I'd guess that there has to be a boost stage as well, since at any time the mains voltage might be lower than 230 V, and besides you always need some headroom for IGBT voltage drops and the like.

@Gnome posted some internal pictures and speculations. I think we decided that there were wires to a boost inductor in the corner.

[___]

As I recall there were two models that looked very similar and are marketed under different names, and one of them was what one could call double-conversion (at least partially, essentially feeding the high voltage DC side directly from the AC, but feeding all loads from the "inverter"). The trick is to look for the 0ms transfer spec.

[Gabriel_2018]

Then It isn't what I had thouht. I Hoped It was an Infini V evolution, but It isn't.

[Gnome]

It is an Axpert with double conversion. So the output is always running from the battery. And the charger switches in and out depending on load.

They charger also has a much wider range than the other Axpert models. They claim 120v -> 280v as the input range. 

[Gnome]

Forgot to mention, I know it is double conversion because the output doesn't vary regardless of what the input does. (ie> Input sits at 240v at night, 220v during the day, my output is always exactly 230v)

Additionally the output waveform is a perfect sine whereas the utility wave form is a little bit noisy.

The downside however is, when I turn on big loads there is a slight dimming of the lights.

IE> whenever the fridge compressor clicks on the lights dim very slightly. I've had a look on my oscilloscope and the reason is because there is a slight voltage drop followed by the inverter compensating. I don't consider it unexpected. I doubt many inverters can avoid some voltage fluctuation as loads are connected and disconnected. Especially inductive loads like fridges, air conditioners, vacuum, etc. 

[___]

2 hours ago, Gnome said:

The downside however is, when I turn on big loads there is a slight dimming of the lights.

Power is proportional to the square of the voltage. Even a 5V drop (that's like 2%) causes a significant dimming in lights. Hence... I am not too concerned about it. Lights tend to overreact in a manner of speaking :-)