Transfer Function Of A Field Controlled Dc Motor
Transfer function of a field controlled DC motor:
It is clear from the above equation that, to have a linear system, one current must be maintained constant while the other current becomes the input current. First, we shall consider the field current controlled motor, which provides a substantial power amplification. Then we have, in Laplace transform notation,
where TL(s) is the load torque and Td(s) is the disturbance torque, which is often negligible. However, the disturbance torque often must be considered in systems subjected to external forces such as antenna wind-gust forces. The load torque for rotating inertia, as shown in Figure 1, is written as
Rearranging, we have,
Fig: 2 Block diagram model of field controlled DC motor.
Therefore, the transfer function of the motor-load combination, with Td(s) = 0, is
The block diagram model of the field-controlled DC motor is shown in Figure 2. Alternatively, the transfer function may be written in terms of the time