JMAG-RT data files are obtained by running the JMAG simulation in advance and are stored in a lookup table form. During the PSIM simulation, JMAG is no longer needed, and PSIM interfaces directly with the JMAG-RT data.
The main advantage of JMAG-RT is that, since JMAG-RT data are obtained from JMAG simulation, the accuracy of a JMAG-RT model is comparable to that of a dynamic JMAG model. However, since JMAG is not involved in the simulation, the simulation speed is much faster.
MagCoupler-RT does not require JMAG, only the JMAG-RT files.