Transient Analysis of a Voltage-Regulated Aircraft D-C System

The system consisting of a single generator and a carbon pile voltage regulator is a closed-loop regulating system of the proportional type. As such, its stability and dynamic characteristics can be analyzed by the standard theory of servomechanisms. It is, however, necessary to define the variable quantities very carefully as they are not easily recognizable or measurable. For this system it is convenient to utilize the concept of an error transfer function (defined in this paper) rather than to use the system transfer function common in servomechanism literature. When this is done the criteria for frequency spectrum analysis are altered somewhat, as discussed before. The purpose of the foregoing analysis has been to simplify the problem of improving an existing regulator-generator system. A complete loop transfer function can be written in terms of the regulator and generator parameters. From this it can be seen by inspection whether a given system will be stable. For stable systems the effect of changing parameters can easily be determined by examining equations 2, 10, 21, and 22. It is clear that the regulator characteristics alone do not determine the stability of the system. The generator and regulator characteristics must be considered together instead of separately. When the same regulator is used with two different generators, one system may be stable while the other is not. This can be due to the difference of the generator characteristics alone.