Powerstar W7 Inverter/ Charger Teardown
I bought this for use in our 3.18kW Hybrid/Off grid PV system.
This inverter is rated at 230V 60Hz, 3000W continuous, 3x surge capability.
It can be used as an off grid inverter, charger, or UPS mode.
Carton sticker. It weighs quite a bit too.
After some wrestling about, it is out of the box.
It is wrapped in plastic and two cushion foams on the ends.
Eight screws and we pop the hood.
Ooops, forgot to take a pic of the sticker on the side of the inverter. Here it is.
Back of the front panel and LCD board.
The 3kVA toroidal transformer is huge.
Banana for scale.
Filter inductor connected in series with the transformer HV side.
The power board is underneath.
Battery input and remote control jack.
Fan blows into the heatsinks - good!
mains input and output connections. There are separate breakers for input and output.
High side power MOSFETs.
These are IRFB4310 devices.
These are rated at 140A 100V.
All are the same batch and date codes. Perfect for paralleling.
There is a bit of rust on the chassis as this was a relatively old stock unit.
Battery positive connection is directly to the heatsink which are connected to the MOSFET drain terminals.
Underneath the LED PCB.
Low side MOSFETs.
Sub PCB for the remote control jack.
Same IRFB4310 MOSFETS and same batch and date codes.
Output noise filtering ferrite.
Transformer secondary filter inductor.
Power board part number.
Control board part number.
Main transformer part number.
TO-220 devices hanging in free air. Not sure how much help that "heatsink" provides in cooling.
TLP350 drivers for the MOSFETs.
There are 4 banks of MOSFETs in this inverter. These opto couplers are used for the high side FETs and the low side are driven by the SOT-89 devices nearby.
Chassis earthing connection.
Besides the inverter, We also get this in the box.
Remote panel, battery terminal and mains connector covers, manual and screws.
Build quality looks OK but the lack of heatsink goop on the main switching devices worries me as I have repaired many inverters (different brand) that kept failing, the only fix to stop it blowing up? Adding heatsink goop! This brand seems to have a good track record but the OCD in me wants to add goop. We shall see.
No testing for now as I have not wired it up to the main system yet. Once I do, we shall take measurements and update this page.
13 Aug 2016:
I took the inverter apart again to put thermal grease between the switching devices and the heatsink.
The whole power stage could be taken out as one big module.
Big supply bulk caps are in between the heatsinks.
Heat should not be a problem as the fan blows air through the middle of the two heatsinks.
With the heatsinks removed, We have a clear view of the "Ruelicon" brand caps.
100V 6800uF each rated 105degC. Or so they say.
As I previously thought. The switching devices are mounted dry on the heatsink.
That is not good.
Under the control board.
Not much to see here, just a bunch of passives.
The heatsink faces are machined but very roughly.
There are also a lot of mishaps with the drill/tap.
Same thing here.
I put dabs of goop under each device to improve heat transfer.
Once wired up, It runs at a no load battery current of 483mA.
Battery voltage was at 53V so that is about 25.6W idle consumption.
Charger peaked at 29A on a 90% SoC battery.
It has been raining non stop for over a week now, last full charge was 8 days ago so I really had to get this done and charge via mains or risk damaging the battery bank.
There is a dead line on the LCD but still readable.
23 Feb 2017:
While I was out of town, dad called and said the system was out and there was no power. I came back home to find this, breaker tripped and there are a bunch of mosfets blown.
I contacted the supplier and did some troubleshooting and found out which parts are blown. Supplier sent me replacements free of charge as I was still under warranty.
There were 7 mosfets from two banks that were damaged and one mosfet driver chip that needed replacing.
Replaced 2 banks of 6 mosfets each and one TLP350 driver.
Quick power up on the bench and it seems to be working.
Output voltage is correct
There is proper switching waveforms on the transformer legs.
Frequency is about right.
My bench was pretty messy so I had it on the chair.
Let it run on the bench powersupply overnight on idle to burn in.
The snubber resistors get really hot.
And also the main output filter cap.
This regulator on the control board gets really hot. I should put a heatsink on it.
Transformer and inductor coil gets warm too.
Installed it in the system now and running the fridge. I shall put it all together after running it a few days and making sure all is well.
Page created and copyright R.Quan ©12 Aug 2016.