Doubly excited electromechanical system - Electrical Machines

Doubly excited electromechanical system

Doubly excited electromechanical system

By keeping the rotor at a fixed position the switches S1 and S2 are closed. The differential electrical input to the system is equal to 

As long as the physical geometry of an electromagnetic system remains same the inductances also maintained constant.

Since the above system cannot produce any mechanical output. As the rotor is released, it starts rotating by torque T. 

Consider its rotation through a small angular displacement d(theta).

The torque developed also depends upon the angular derivatives of inductances along with stator and rotor currents.

For producing reluctance torque single excitation is sufficient but for getting mutual torque multi excitations are required.

The direction of reluctance torque cannot be reversed by reversing the excitation current whereas the mutual torque direction can be reversed either by reversing stator  current or rotor current but not both.