DC to AC Inverter Test

[mokie]

Hello, I'm having problems with an air conditioning machine. I think that the problem is in the inverter IC. The model of this inverter is PS21245-E.

This IC transforms 320v DC to 20-300v 3-fase AC (and variable frequency).
I have already desoldered one side to see the identification of the IC.

I ask your help in order to check if this inverter IC is working or not.

The datasheet is here: http://www.ineltron.de/english/mitsu.../PS21245-E.pdf

Thanks in advance.

[budm]

Re: DC to AC Inverter Test

If you look at the internal diagram figure 3, you can at least test the individual MOSFETs (6) to see if they are shorted out or not by using Ohm mode to test between pin P & pin U, P & V, P &W, N & U, N & V, N & W. Not much you can do to test the drive and the control circuit. You need the diagram of the whole system to see how this IC is being used so you can test voltages and signals, it 3-phase motor drive IC.

[mokie]

Re: DC to AC Inverter Test

The measures in ohm scale are (first letter with positive and the second one with negative):

P-U: 4.24 Mohm
P-V: 4.24 Mohm
P-W: 4.24 Mohm
P-N: 7.87 Mohm

N-U: open line
N-V: open line
N-W: open line
N-P: open line

and in diode scale are:

P-U: open line
P-V: open line
P-W: open line
P-N: open line

N-U: 0.435 v
N-V: 0.435 v
N-W: 0.435 v
N-P: 0.797 v

[budm]

Re: DC to AC Inverter Test

Well it is not shorted, beside if it is shorted, it would have caused the protection circuit to kick in. I f you do have voltage present between P and N as shown in figure 2, then you need to find out if you do have correct CONTROL signals applied to the IC or not, that is when the diagram of the unit will help, otherwise you can take a chance by replacing the IC.