A convenient way to do this is to use a Configurable Subsystem.
Run the simulation first with the sub-cycle average model. Once the simulation has reached the desired operating point, store the system state. Then switch the configurable subsystem to the switched model and restart the simulation from the stored system state.
The complete workflow is described in this forum post:
I’ve also attached a small boost converter example. Run the simulation script via Simulation > Simulation Scripts…. The script demonstrates exactly this workflow: it runs the average model, stores the system state, switches to the switched model, and continues the simulation from the stored state.
boost_converter_configuration_change.plecs (15.4 KB)