Question 6.5.2: Develop a model of the field-controlled motor shown in Figure......

The voltage \ v_{f} is applied to the field circuit, whose inductance and resistance are L_{f}{\mathrm{~and~}}R_{f}. No back emf exists in the field circuit, and Kirchhoff’s voltage law applied to the field circuit gives

v_{f}=R_{f}i_{f}+L_{f}{\frac{d i_{f}}{d t}}                (1)

For the inertia I,

I\frac{d\omega}{d t}=T-c\omega-T_{L}=K_{T}{i_{f}}-c\omega-T_{L}                (2)

where {{T}}_{L} is the load torque. These two equations form the motor model.