Small Signal Model of DC Machine — Lesson 2

This lesson covers the concept of small signal models in DC machines. It explains how these models are derived from large signal models using certain approximations and the method of small perturbations. The lesson further discusses the application of these models in control system applications. It also elaborates on the process of obtaining small signal models for a separately excited DC machine and how these models can be used to determine the machine's behavior under various conditions. For instance, the lesson illustrates how changes in armature voltage can affect the speed of the machine.

Video Highlights

00:24 - Introduction
05:25 - Explanation of the equations for steady state model
09:04 - External inputs and how small disturbances affect the system
25:20 - Explanation of the small signal model for the machine
34:27 - Explanation of how to recast the small signal equations in the form of the state variable
38:01 - Discussion on how to design a close loop system for a DC machine
41:59 - Explanation of how to evaluate the response between speed and armature voltage

Key Takeaways

- Small signal models are derived from large signal models using certain approximations and the method of small perturbations.
- These models are particularly useful in control system applications where the disturbances applied are generally small.
- The small signal model for a separately excited DC machine can be obtained by simplifying the equations developed for a four-coil system.
- Changes in armature voltage can significantly affect the speed of the machine. Understanding this relationship is crucial for designing control systems.
- The small signal model provides a useful tool for studying the behavior of the system under various conditions.