Dynamic Equations of DC Machines — Lesson 1

This lesson covers the derivation and understanding of machine equations, with a focus on Direct Current (DC) machines. It starts with the continuation of the machine equations derived in the previous lesson, explaining the expressions for a four-coil primitive machine. The lesson then delves into the system description in the optional impedance form. It further explains the concept of self-impedance, mutual impedance, and speed EMF terms. The lesson also covers the description of a DC machine, explaining the field winding, armature, and the role of brushes. It also discusses the concept of a pseudo stationary coil and how it affects the machine description. The lesson concludes with the derivation of the electrical system equation for the DC machine and the concept of large signal models and small signal models.

Video Highlights

00:12 - Introduction
05:45 - Explanation of the armature in the DC machine and its behavior
12:17 - Discussion on the steady state equations for the DC machine
16:55 - Explanation of the expressions for series and compound DC machines
24:34 - Explanation of the armature expressions and compensating windings
33:42 - Discussion on armature interconnection
38:14 - Explanation of the large signal models and their applications
42:11 - Discussion on the method of perturbations and the concept of small signal models
45:02 - Explanation of the disturbance response in the DC machine

Key Takeaways

- In a four-coil primitive machine, there are two real coils fixed in space and two factious coils which are stationary.
- The DC machine consists of a field winding and an armature, with the armature behaving like a pseudo stationary coil due to the arrangement of brushes.
- The electrical system equation for the DC machine can be derived using the concepts of self-impedance, mutual impedance, and speed EMF terms.
- Large signal models are used to study the response of a system to a large voltage, while small signal models are used for close loop control of a system.