Three phase inveter ouput issuse with optocouplers islation

Hi,

So the signal path is:
Microcontroller -> cable -> R1 -> IC1 -> ? -> gate driver
And all the signaling is somehow defined by: voltage, current, timing
.. basically that´s all ...


look at your own schematic: do you see
* what microcontroller is used? It´s signal output voltage and/vs current?
* what cable and connectors are used?
* the value of R1?
* the power supply (voltage) to IC1?
* why there is an R9 (what value) in series to the supply of IC1? (I highly doubt that this is accrding datasheet recommendations)
* the power supply decoupling capacitor(s)?
* what is "INH1"
* what gate driver is used? What voltage it is supplied with, if the external connections are according datasheet?

I guess you recognize we really miss a lot of essential informations... ;-)

If you want us to check any IC function and specifications .. please post links to their datasheets (directly at the manufacturer site)
(This makes it more eaysy for us, less time consuming, avoids misunderstandings ... and thus gives faster and more accurate feedback for you.)

***
Regardless ... whether informations are missing.

What did you do so far? (By telling us the results, we see your effort, we see what possible problems can already be excluded. No need for wild guessing)
One appoach should be to trace the signal ... according the above mentioned signal path:
* does the microcontroller output the expected signal? ... according voltage level and timing..
* then the cable input ... and output ..
* the resistor input and output ..
... step by step ...
...
for this you need to have the datasheets by hand . . to know the specified output levels .. as well as the specified input thresholds

.. this - at least - is how I would do the debugging

Klaus

KlausST said:

Hi,

So the signal path is:
Microcontroller -> cable -> R1 -> IC1 -> ? -> gate driver
And all the signaling is somehow defined by: voltage, current, timing
.. basically that´s all ...


look at your own schematic: do you see
* what microcontroller is used? It´s signal output voltage and/vs current?
* what cable and connectors are used?
* the value of R1?
* the power supply (voltage) to IC1?
* why there is an R9 (what value) in series to the supply of IC1? (I highly doubt that this is accrding datasheet recommendations)
* the power supply decoupling capacitor(s)?
* what is "INH1"
* what gate driver is used? What voltage it is supplied with, if the external connections are according datasheet?

I guess you recognize we really miss a lot of essential informations... ;-)

If you want us to check any IC function and specifications .. please post links to their datasheets (directly at the manufacturer site)
(This makes it more eaysy for us, less time consuming, avoids misunderstandings ... and thus gives faster and more accurate feedback for you.)

***
Regardless ... whether informations are missing.

What did you do so far? (By telling us the results, we see your effort, we see what possible problems can already be excluded. No need for wild guessing)
One appoach should be to trace the signal ... according the above mentioned signal path:
* does the microcontroller output the expected signal? ... according voltage level and timing..
* then the cable input ... and output ..
* the resistor input and output ..
... step by step ...
...
for this you need to have the datasheets by hand . . to know the specified output levels .. as well as the specified input thresholds

.. this - at least - is how I would do the debugging

Klaus

Click to expand...

Hi, thank you so much for replying
*So, now for the power stage testing, i only use a waveform generator, and the final signal to the gate driver input is (should be) 5volts as high level, and 0 as low level pwm signal.
*i use the two jumper wires(signal and ground) with a adapter from waveform generator connected to the opto board, and the rest connection to gate driver board both are jumper wires
*R1 is 120ohm
*vcc is 15V
*R9 i use is 1.8kohm
*decoupling caps are 400uf
*INH1 is the input of gate driver also the ouput of opto, they are connected
*gate driver is ir2130

*i observed the waveform from signal generator on scope first, there is some overshoot 8v and -1v, but when i directly connect the generator to inputs of gate driver, the mosfet is swithcing correctly(without opto), i only give one PIN a signal at a time, so i leave the INH pin open when i switch INL and the other way around.
And after i apply the opto, i frist observe the output from opto, i get like 9V as high and -1v as low, i tried to use different pull up res, but i couldn't lower the high level voltage to 5V, so just give this ouput signal from opto to gate driver anyway, and the mosfet switching is correct both low side and high side(individually test), so the ISSUE occurs when i both plug the ouputs from opto to gate driver's inputs ( eg, INH2 and INL2) the same time, then gate driver shut down the mosfet switching, and still i only give one input signal on opto board at a time, for example i give signal to input of low side opto, and i will not give any input signal to high side opto, there should be a output signal from low side opto and no signal from high side opot. But somehow the gate driver just shut dwon the mosfet switching.
i am thinking maybe the issue is that both ouput side of low side and high side opto shared the same ground with driver circuit ground. But i can not serapate them.