SPRACM9B June 2019 – November 2020 F29H850TU , TMS320F28384D , TMS320F28384S , TMS320F28386D , TMS320F28386S , TMS320F28388D , TMS320F28388S , TMS320F28P650DH , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK , TMS320F28P659DH-Q1 , TMS320F28P659DK-Q1 , TMS320F28P659SH-Q1
The board has various current sense methods, such as shunt, LEM, and SDFM. Overcurrent monitoring is provided for signals generated from shunt and LEM using an on-chip comparator subsystem (CMPSS) module. The module has a programmable comparator and a programmable digital filter. The comparator generates the protection signal. The reference to the comparator is user programmable for both positive and negative currents. The digital filter module qualifies the comparator output signal, verifying its sanity by periodically sampling and validating the signal for a certain count time within a certain count window, where the periodicity, count, and count window are user programmable.
In the Expressions window, users can see the following variables:
tripFlagDMC is a flag variable that represents the overcurrent trip status of the inverter. If this flag is set, then you can adjust the previous settings and try to rerun the inverter by setting clearTripFlagDMC to 1. This clears tripFlagDMC and restarts the PWMs.
The default current limit setting is to shut down at 8A. Any of these settings can be fine-tuned to suit your system. When satisfactory values are identified, write them down, modify the code with these new values, and rebuild and reload for further tests.
It is possible to shut down the inverter using a digital signal from an external source through H9. No code is provided currently, but it can be used as an exercise to experiment and learn.