IMC101 - Current sensing offset for Leg Shunt mode issue

[davisonInfineon]

I am having a problem with viewing scaled current on the IMC101TT038XUMA1. I have the parameters set to use Leg Shunt, and have current sensing gain and offset circuits going to the IMC101 inputs IU, IV, and IW. See below for schematic.

I've noticed that the REFV and REVW pins of the IMC101 (DAC generation of voltages for gatekill overcurrent comparator) are at ZERO volts, even when leg shunt mode is enabled. These should be at the value that corresponds to overcurrent (for me about 4.1V). The REFU pin shows the correct DAC value of 4.1V.

Additionally, when reading the value of IV and IW in MCEDesigner, the reading shows the current as the minimum value (-20.1A) with some noise. All of this is true before even starting the motor. Because of this error, the gatekill fault is always active, and therefore prevents the motor from running. 

Can someone help me with this problem? Do the REFU, REFV, and REFW inputs need to be tied together?

[LinGuohui · Accepted solution]

Hi @davisonInfineon 

Can someone help me with this problem? Do the REFU, REFV, and REFW inputs need to be tied together?

Yes, You should connect REFU, REFV, and REFW together.

Refer the software UM, three comparators of UVW are enable when using leg mode.

[davisonInfineon]

Thank you LinGuoHui. This solved my problem.

Another thing I realized now that I also hadn't realized before is that when gatekill fault is tripped, most other functionality of the IMC101 chip stops working.