DC motors a with in-series excitation are very similar to those with independent excitation, except that the circuits of the stator and the rotor are connected in series. Therefore, the current flowing through both circuits is the same and is also what induces the magnetic flux that excites the rotor. As for the rest, everything stated concerning the independent excitation motor is applicable to the in-series excitation motor. Figure 10 depicts the outline of an electromechanical DC motor with in-series excitation, while Figure 11 shows its corresponding Bond Graph.
Fig. 10. Electromechanical diagram of a DC motor with in-series excitation.
Fig. 11. Bond-Graph model of a DC motor with in-series excitation.