Hello, , after i bought my third gtil1000 i noticed that there are a few modifications, The one that is affecting the sunScreen print is the fact that a few relays are added to switch the mains on and off from the powerstage. These relais are powered of 12 volt, and you guessed it, that 12v is coming via the sunScreen print if you mount that. As a result the lithium battery will be empty before you know it. My workaround is to feed the relay modification with the 12v BEFORE it enters the sunScreen print.
The other modification they applied was the change from transistors to fets to switch the fans, so no need to change transistors. Hope this info helps.
hello, the relais are 12V fed, but are controlled by a fet or transistor that is controlled by the pic processor that does the ac stuff.
And for your information, the 2 igbt's and the heatsink are my own modification right out of the box :-)
The igbt's are k40t120 from infinion, i got those from an old ups (1200v 40a)
i also got rid of that peski little fan and i use a giant heatsink mounted on top of this aluminium block. My other 2 gtils have that modification also and get never above 40c.
Hi Ben,
Thanks for the information. I'm in contact with someone who got a new Sun2000 with the same relay modification on the motherboard. To me, this is really good news because it means the manufacturer is trying a hardware solution to brownout and it validates the SunScreen approach. Based on your description, it looks like the relay engages whenever there is 12V and not when it senses a good AC signal. Since the 12V DC is from the AC and the inverter micro is 3.3V, it looks like the relay should disengage as the 12v drops and probably before it reaches 3.3V to ensure there is no AC when brownout happens. SunScreen keeps the micro from going into brownout whether there is AC or not. As long as during brownout, there is no AC, there should be no damage. If the relays are draining the batteries sooner, I think that is still okay as long as the battery can last during the momentary power loss which is usually a few seconds. If the power is out long enough for the battery to run out even with the relays, it will switch off very fast and the micro probably doesn't experience brownout very long and the AC would be off by then. Your rerouting of the 12V does allow the battery to last longer, but I think it's unecessary because brownout is still prevented during the loss of AC power. However, without your rerouting, it does make their relay modification ineffective because the relay doesn't turn off when the AC is dropping out. Your modification does allow basically "double" brownout protection, one using their relay and the other using SunScreen.
On another note, it appears there are multiple causes to the AC short problem and that the manufacturer is trying to address. 1. is what we talked about already with brownout. and 2. is an AC short when the 2 IGBTs prematurely fail during normal operating conditions most likely from heat when there is too much voltage or current somehow. If you look at the new board, they've changed the IGBT to higher voltage and current rating and they used a full body package (it doesn't have the metal tab). I think they are the components mounted to the end of the heatsink. For the Sun2000, the IGBT is now 1200V, 24 A where previously it was 600V 20A. The full body is supposed to be able to dissipate the heat better. So this appears at first to be a good solution because it makes the IGBT more robust. But I noticed they have turn off delay 3 times worse than before which means significant more heat which could negate the higher ratings. I've tried slower IGBTs on my unit and they do blow sooner so turn off delay is a factor. I'm now trying IGBTs that are signifcantly faster and it seems more stable. I'm thinking they might not have realized the issue could be a heat issue from slower IGBTs. Anyways, if you don't mind taking a picture of the IGBT on the new Sun1000 so I can see which ones they are using now. The one for the Sun2000 are CRMicro G24T120AK3SD.