This information is part of the Modelica Standard Library maintained by the Modelica Association.

This example demonstrates how to use a coupling to implement a drive consisting if two permanent magnet DC machines. Note that dcpm1 is turning in the positive direction, whereas dcpm2 is turning in the opposite direction. This is evident by comparing speedSensor1.w and speedSensor2.w. Therefore, the armature of dcpm2 is connected reversed to the source.

Machine dcpm1 starts the drive with a voltage ramp up to half of no-load speed, the armature of dcpm2 is not connected. Since the induced voltage of dcpm2 is the same as that of dcdcInverter2, the switch is closed without any transient. After that, the armature voltage of dcpm2 is slightly increased, causing dcpm2 to drive as motor and dcpm1 to brake as generator. Therefore, the speed coupling.w increases.

Note that in stationary operation the battery only delivers the losses of both machines, since power is exchanged directly between both machines. Only during short time spans with transient operation power is delivered back to the battery, which is the case after accelerating the whole drive when angular velocity settles. An additional energy storage between the battery and the inverters (like a large capacitor or a super capacitor) would help to avoid such situations and to smooth possible current spikes.