Hello folks,

I have an 3KW 24V inverter having fault code 57. I removed all transistors and test all drivers. Output, buck and PV IGBT have correct voltage values, when measuring the voltage between Source and Gate (5V) while the IGBT removed.

But the voltage across battery Mosfets and Charge IGBT is 0V.

I replaced the SG3525 and still same issue. I checked all measure around 3525 all correct.

What do you think the 0V issue is coming from? Maybe from controller?

 

The schematic reference I referred to during my investigation is 

 

 

And here is the inverter

12 hours ago, Adnano said:

when measuring the voltage between Source and Gate (5V) while the IGBT removed.

I assume you mean between emitter and gate.

12 hours ago, Adnano said:

But the voltage across battery Mosfets and Charge IGBT is 0V.

I assume you mean gate to source and gate to emitter voltages.

I know nothing about the charge IGBT circuit; that's something that only some 24 V models have. As for the MOSFET gates, you have to trace the circuit further. Are you getting pulses at the output of TX8? If so, continue checking to the right of TX8. Otherwise, continue checking to the left.

Have you checked +12 V and -12 V supplies for the SG3525? For most tests, you may need to force the SG3525 to turn on (make sure there is no battery voltage, use power supplies for +12 V and -12 V separately); see the repair and hardware upgrades index for details.

Edit: I can't find the link myself; basically, just short the output of the opto to force  the SG3525 to produce pulses for the MOSFETs. Don't do this if there is a battery connected, or if you do, make sure that the control board is removed.

 

Edited May 5, 20242 yr by Coulomb

Thanks @Coulomb for your kind reply.

I have tried to shorten the opto's output and I found out that pulses are generating.

What is the next step?

8 hours ago, Adnano said:

What is the next step?

If they make it all the way to all the MOSFET gates, with roughly +14 V and -12 V on each, as shown here, then you're done. Otherwise, you troubleshoot and figure out where the signal dies, or why it doesn't go high or low enough.

Do you mean keeping the optocoupler short will not affect the inverter functionality?

No, shorting the opto coupler output is just a way of keeping the SG3525 running so that you can do tests on the bench. Just have +12V and - 12V supplied by bench power supplies, nothing on the battery terminals. 

I supplied the IC with +12 and -12 v, it is producing signals perfectly. 

What is the next step? 

Thanks

Here's the circuit 

 

What do you measure on the MOSFET gates with an oscilloscope?

Yeah correct

Actually I measured the signals directly on 3525

33 minutes ago, Adnano said:

Yeah correct

All the gates? +14 V and -12 V?

If so, what is the problem?

Edit: I see you have all the transistors out. It's probably a good idea to check the gate drivers for the DC->AC converter and buck stage IGBTs, as described here. If all that tests OK, then replace all the transistors and try running it from a strong bench power supply to the battery terminals.

Edited May 9, 20242 yr by Coulomb

The problem is originally that pulses are not generated from the 3525. It only gives output when shorting the optocoupler and supplying it with an external 24V.

10 hours ago, Adnano said:

The problem is originally that pulses are not generated from the 3525.

Ah. Then the problem is that the control board is not enabling the 3525, or the opto or associated circuit is not working.

You could try this: remove the short from pins 3 and4 of the opto, and try to start the 3525 by connecting pin 2 to GND. It might be more convenient to connect pins 2 and 3 of the opto with a ≈1.2 kΩ resistor. That will test that the opto is working.

It's possible that without the transistors installed, the DSP will detect some problem and go into a fault state rather than try to start the DC-DC converter.

Edited May 10, 20242 yr by Coulomb

Look, I found this video that is similar to my case. 

If u can notice, the voltage at Mosfet gate is about 7V when disconnecting all transistors

Unfortunately I don't have another controller to test

I measured the voltage between Shutdown pin and Ground(-12V) pin of 3525, it gives 1.2V, which means the shutdown pin is almost near to -12V pin, then the IC is in stop state!

In other hand, the voltage between pin 2 of opto-coupler and -12V is 24V, which means the Shutdown is not activated from DSP!

Hello! I am in the same situation..Have you found the defect?