cristof wrote: ↑
Wed, 24 Oct 2018, 02:41
escuse me for my bad english this is a Google translation.
It's quite readable, no problem.
10 months ago I bought a MPPSOLAR MPI 5.5KW hybrid inverter. this inverter is the same as the model from infiny solar voltronic power. After a few days of operation, it broke down, error 6.
For other readers, this is the over temperature fault code.
After long discussions with MPP SOLAR, I received a new inverter, the same model. the second comes in turn to break down with the same error code 6. This error code corespond to a temperature error in the charger part (DC to DC board). Whenever they broke down the charger did not charge more than 25A at 62V DC. my batteries are lithium ion, 15S.
I take it from the 62 V you mention that these are not LiFePO₄ lithium iron phosphate (LFP), but rather one of the other lithium chemistries that charges to some 4.1 VPC. 4.10 x 15 = 61.5 V, which is very high for a nominally 48 V battery. These inverters are designed for lead acid batteries; the "Features" tab of xxx states "Compatible with mainstream VRLA lead acid batteries (48v only)". Usually this chemistry, when used with off grid inverters (the only ones I'm really familiar with) are used in 14S configuration, not 15S. I suspect that this is the root of your problems; the battery voltage at end of charge is too high for the charger MOSFETs and associated circuit.
I found that on the first board DC to DC, one of the MOSFET was exploded (IRFB7730).
This is a 75 V MOSFET, the same voltage (but different part number) to the original MOSFETs found in the off grid inverters. These were limited to under 60 VDC; you could not even set the absorb ("CV") voltage setting to higher than 58.4 V. So pushing these devices higher, even though the user manual specifications say 63 V, seems unwise.
On the 2nd board the MOSFETs are of another model (CSD19505KCS).
Those are at least rated to 80 V.
We recommend upgrading
the capacitors in the off-grid models to 80 V long life parts, and the MOSFETs to 100 V parts. So you can see how low your operating margin would have been.
On the 2nd board, the Mosfets did not explode, but transil 5KP54A diodes located next to the MOSFETs were disbursed from the board and fell into the bottom of the case. When I looked at the data, I noticed that the temperature had risen to 102 ° C, and this in a few seconds.
These seem to be transient voltage devices, with a "nominal" voltage of 54 V. Datasheet here
. They seem to start conducting (5 mA) at 60.0 - 66.3 V, and clamp fully at 87.1 V. It's possible that devices near the lower end of the breakdown voltage range (60.0 V) would overheat when subjected to 61.5 V or 62.0 V for extended time. You could say that this is poor design, or at least misleading advertising (the specification "DC voltage range 40-63 V).
Do you think I can fix the boards? I can buy MOSFETs and transil diodes, but without any diagrams I do not know if there are other parts to change.
Someone can help me.
I happened to have a 3 kW model for observation recently, and could not find a good service manual. I did find one, which even included some schematic diagrams, but they were not detailed at all, they were more of an overview. I also found it confusing how there seemed to be so many power supplies, and what looked to be the "main" power supply had no schematic overview at all. I decided that there wasn't enough detail to perform a repair when the customer would be paying. I did not find a better service manual. Perhaps MPPSolar will send you a service manual specific to your model, perhaps as a way of "shutting up" a difficult customer. Whatever works. It's so frustrating that these things aren't more readily available any more, with the advent of the unlicensed clones.
If you do manage to find a service manual, please post it here, assuming you aren't told not to do that. If you can't find one, the schematics aren't all that difficult to trace, just time consuming. I've done bits and pieces for the off-grid 5 kVA models.
You may find features in common with the off-grid models, so check the index of our PIP-4048MS and PIP-5048MS Inverters
topic. In particular, you'll need to check the gate drivers for the MOSFETs, and associated components. These often fail when the MOSFETs melt; the gate shorts to the drain and/or source, leading to massive overloads.
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.