There are various configurations for the variable output DC solutions. Generally you are after a variable output DC sink and source device, so you can provide and absorb energy from your test piece. Generally the DC source is providing a DC voltage to a test inverter which in turn powers an electric motor.
The variable nature of the device enables different battery pack configurations to be replicated by adjusting the demand value. Coupled to a battery modelling device you can adjust the DC level in line with your modelling.
Simple models can be created in the CADET open area, or more complicated models in MatLab or dSpace and the setpoints passed through to CADET to handle.
These DC emulators typically range from 0-1200VDC and up to 1MW power and beyond.