PJ 15KW Quirks

20 minutes ago, wonka said:

Always looking for a challenge!

Challenge granted 🤣

I see the displays you've added to the front of the inverter in an attempt to get some sort of useful information out of it.  Methinks you'll drool over all the settings and data available on the Genetry Solar WiFi board...

Absolutely... already drooling at the thought of it!

Not like you can use one of the 3 PWM fan channels together with an external 15K thermistor to one of the 6 thermistor channels to have the WiFi board automatically throttle up a circulation pump if the oil starts to get a little warm 😉

yep, thats the kind of thing that gets me excited.  I already have the pump but so far haven't needed it.  Not sure what summer temps will bring though; my installation is in an un-condtioned outbuilding.  Last fall, after I got it all put together, a 6kw load for an hour only brought the oil temp up to about 130*.  I was able to manage that pretty well with just natural convection currents and a fan, but the ambient temp was only 70*.  Our summers can be quite hot, sometimes 100+ for a week or longer, so the pump may end up being necessary.

One question I have regarding the GS board; how does it bode in the RFI/EMI department? I've come to accept that I will probably just have to live with the increased noise levels on my amateur radio gear as my inverter and the MPPT's (MSB) are pretty noisy under load  I am, however, curious if the board will be affected when I transmit on various bands, sometimes at power levels >500watts.  I operate HF, VHF and UHF within proximity of the inverter gear.  I've noticed a few times that the voltage regulation will take some wild swings under certain conditions when I transmit but I haven't been able to reproduce that very consistently so there is still some detective work to be done on my end. Various RF bypass caps in different locations have seemed to reduce the symptoms to moot at this time so I haven't dug much further.

38 minutes ago, wonka said:

One question I have regarding the GS board; how does it bode in the RFI/EMI department?

You might be a very valuable test bench in that regard 😉.  Like any designer, I want to believe it's solid, but until tested in every situation, it's hard to say.  There's significant EMI inside the inverter chassis...and it's pretty stable, so I don't envision there being any unwarranted issues.

38 minutes ago, wonka said:

I've noticed a few times that the voltage regulation will take some wild swings under certain conditions when I transmit but I haven't been able to reproduce that very consistently so there is still some detective work to be done on my end

Have to say that I'm not surprised at all: There is no true AC-DC isolation in a PJ inverter.  If you look at the PJ LF Control board, you'll probably notice the 4x8 block of 32 resistors on the PJ control board...each one is 499K ohms.  These form 2 strings of resistors in series.  One side connects to one phase of the AC output (i.e. 120v).  The other side directly connects to DC ground and an op-amp circuit.

This means that the AC output signal has roughly 16 megohms impedance to the DC control circuitry...and as someone working in RF, you know how much of an antenna that could be.

Adding insult to injury, after this signal is "rectified" by an op-amp (diodes in the feedback path, etc.), the output is then run over another foot of wires to the front panel adjustment knob, before being fed pretty much directly into the CPU.  This is another huge path for noise to wreck havoc with the AC output feedback--not to mention giving a great "input" for the inverter to get into wild oscillations with itself (which is part of the cause of your opening comment).

Sometimes it's a wonder that it works at all.

The GS board setup is considerably different: at least for the current revisions of boards, I am using optoisolators to truly isolate the AC side of the inverter from the DC battery side.  Impedance is considerably lower: less than 200K into the optoisolators...and less than 4.7K impedance directly into the CPU...with no ridiculous "adjustment" cable going another foot to the front panel.  All voltage regulation/calibration adjustments, etc. are 100% handled via firmware...which has a surprisingly high resistance to EMI 🤪.

So with that in mind...I think the GS control board should be considerably better.

16 hours ago, Sid Genetry Solar said:

You might be a very valuable test bench in that regard 😉. 

Happy to oblige.

17 hours ago, Sid Genetry Solar said:

Sometimes it's a wonder that it works at all.

I see what you mean, that explains a lot.  Glad to hear about the opto's on the GS board.  It should be FAR superior.

I'm sold. It sure sounds like the GS board solves all of my problems and gives me the flexibility to tinker the way I'd like to.  I suppose the next step is to place the order.  What's the best way to go about ordering- Call? or via the genetry website contact form?  Do I need to request anything specific for my unit? 

Checked the schematic...impedance to the CPU on the GS board is actually <1k.  The only pitfall with the optos is their (significant) temperature coefficient.  Fortunately, with some external thermistors, we can reduce the temperature error from +15v (i.e. 220 -> 235v) to +4v...but still, future GS board revisions will be switching to a small feedback transformer to solve this issue.  (Impedance: similar.)

Well, if you need any further "tinkers", you're talking to the programmer 😉.  There's not much that can't be tweaked--as a matter of fact, Sean & I have been tinkering with the H-bridge dead time settings lately.  I can easily provide a "tech" update to add/tweak a function as needed.

TBH I'm not super sure...at the end of the day, you're trying to reach someone who is pulled so many different ways during the day (i.e. Sean) 😉.  Thinking the contact form would be the best way to start the conversation; from there, he probably will want to call you.  You're looking for the GS WiFi board + control board upgrade kit; things you would need for your unit (off the top of my head!)...

• GS WiFi board (updated to latest firmware)
  • "big" hall sensor (for WiFi board total output power monitoring)--your inverter does not have this
  • mounting screws for WiFi board (not sure if the "plate" screws on your unit are the same size?  They're M3.)
  • FDBK cable (4-pin XHB straight-through pinout i.e. 1-1, 2-2, 3-3, 4-4, NOT crossed)--your inverter does not have this
  • COMM cable (custom made for GS)
  • Battery wires for WiFi board (it directly powers from the battery terminals, due to the potential high current draw of the fans)
  • XHB-2 connectors for 2-wire fans and/or XHB-4 connectors for PWM 4-wire fans (NOTE: observe pinout!)
• GS LF Control board Rev. A.1 (latest firmware, with thermistors added, output filter caps corrected, all M5 terminal screws installed, tested)
  • NEG spade terminal and wire (long enough to reach the back negative battery terminal)
  • empty XHB-4 connector header (for the thermistors)
  • the RGB power switch + connector (this actually sorta fits into the original power switch hole in the chassis)

You'll obviously need a good bit of electrical expertise and such to get it installed.  Such as: popping the thermistor pins out of the PJ wiring harness, and slipping them into the XHB-4 connector for the GS board.  We may want to schedule a video call so I can try to make sure everything's wired up right before the dreaded "smoke test."