Inverter drive module overvolt fault

[Eamon]

Ok, so the three different components are not available from a single source that I can find so I'm considering substitutions.

For the gate driver, there is an "A" version that says "The UCC27524A adds the ability to handle –5 V directly at the input pins for increased robustness" so I think a straight substitution here is ok.

For the MOSFETs (STW34NM60N), apart from ensuring the voltage rating is 600v or above and the current rating is at or above the rating of the existing ones (34 amps), are there particular attributes that I need to match closely with the existing part? I'm thinking of using the STW45N65M5 which has a 3.5amp higher rating and a 650V rating instead of 600v.

And for the diodes (VS-EPU3006), the datasheet link actually goes to the VS-EPU6006 which is essentially the same but with a 60 amp rating instead of 30 amps.  Can I use the VS-EPU6006 instead?

[Eamon]

  Well the parts arrived and after de-soldering all the power components and testing them I decided that they were all good apart from the gate driver (and an electrolytic cap that I may have inadvertently overheated so replaced that too).  So I put all the original parts back in with a new gate driver and voilà, a functioning inverter compressor driver! 

I have the new components at hand should one of the existing ones fail but as they were not an exact part number replacement anyway I felt best to stick with the originals if they appear to function correctly. 

Now when the PFC turns on, the DC voltage jumps up to 380v instead of dropping slightly and at the point where the "AC plate voltage" previously jumped to ~320v it climbs to 230v and no fault occurs.

I've sunk a lot of hours into this but I've mostly enjoyed it and learnt a heap, not to mention a saving of ~$2500 for a replacement part!

Again, I want to give a special thanks to capt bullshot and florentbr if you guys have a paypal account, I'd like to buy you both a beer/coffee/drink msg me.

[capt bullshot]

You're welcome!
Glad to see the good result of your effort, so the thing is working again with mininum hassle. I would have kept the original power components, too. But that bet could have failed in a spectacular way. My former colleagues always used a good amount of protection when powering up a repaired board for the first time - a carton box put over the DUT, shrapnel protection googles, distance and a remotely controlled power on switch - and someone else nearby to watch them and to call emergency / fire brigade in case.

[piratebriggs]

Hi, Sorry for replying to an old thread - I have a different heatpump to you but with the same inverter board.

Mine has suffered damage to the 15v SMPS section of the board (skid marks) so I've desoldered enough components so I can feed 15v in from an external supply and the activity LED next to the mcu is blinking, however the touchscreen is still reporting "F02 - Inverter Offline" so I'd like to try comminicating with it over the rs485 port to see if that section of the board is intact.

So, I was wondering if you still still have a copy of your test application @Eamon to save me the reverse engineering the ModBUS all over again!

I know there are issues on the power side of the board - the DC bus is shorted/trips the breaker when the main relay turns on but I just wanted to verify that the LV side of the board is OK before putting a lot of time/unloading the parts cannon on it 

Anyway, there's lots of useful info in this thread to help diagnose my board already so Thx all

TTFN