Motor armature voltage feedback circuit

In the thyristor-controlled DC motor transmission system, the fluctuation of the grid voltage, the temperature rise of the motor,
the size of the load, etc. will affect the stability of the motor speed. For this reason, it is necessary to adjust the conduction angle of the thyristor in time to change the output voltage
and thereby correct the speed. What makes this possible is a feedback circuit.
    In situations where steady-state requirements are not high, a motor armature voltage negative feedback circuit is often used , as shown in Figure 16-32. Adjust
the potentiometer RPi to change the negative feedback voltage.