High Performance Control of AC Drives with Matlab / Simulink Models

6.3 Non-Linear Control of Separately Excited DC Motors

Because the separately excited DC motor has the best mechanical characteristics, and it is and one of most widely used DC motors, we will limit our explanation of the control of this motor to our introduction to the topic. Although the DC motor is not being used for advanced drives at this time, presenting this type of motor is beneficial from an educational point of view.

For realizing a linearization of the non-linearity in the mathematical model, a new variable is introduced, proportional to the motor torque [20]:

(6.10)

After taking the derivative of the new variable and making some mathematical arrangements, the following model is derived [18]:

(6.11)

(6.12)

(6.13)

The new model allows us to use linear and cascaded controllers for motor control. The output signals of the controllers are the new variables v1 and v2, which are described from the model as

(6.14)

(6.15)

The control scheme of the motor using the above procedure ...