Inductance in Salient Pole Machine - V — Lesson 6

This lesson covers the derivation of expressions for mutual inductance between the coil on the rotor and the coil on the stator, and the self-inductance of the rotor coil. The lesson also discusses the challenges encountered in deriving an expression for the self-inductance of the stator coil. It further explores the flux density distribution around the air gap and how it changes with respect to the rotor angle. It expalains the concept the Blondel's two-reaction theory, which simplifies the understanding of the machine's behavior. This lesson also covers how to calculate the flux linkage due to the elemental flux.

Video Highlights

00:11 - Introduction
01:07 - Discussion on the difficulties encountered in deriving an expression for self inductance of the stator coil
02:43 - Explanation of a finite element study of a simple machine geometry
07:21 - Explanation of how the flux density distribution around the air gap will look for a salient pole machine
12:18 - Explanation of the variation of inductance with the help of a plot
20:06 - Machine behaviour as if interpoalr regions are associated with large air gaps and low flux density
33:23 - Discussion on the concept of two reaction theory and how it helps in understanding the flux density distribution
46:25 - Explanation of how to calculate the flux linkage due to the elemental flux
49:55 - Discussion on how to calculate the total flux linkage and the inductance

Key Takeaways

- The flux density distribution around the air gap is not constant and changes with respect to the rotor angle.
- The flux density waveform and flux levels in the machine change with respect to the rotor angle, creating challenges in determining the self-inductance of the stator coil.
- The Blondel's two-reaction theory simplifies the understanding of the machine's behavior by assuming two air gaps in the machine, one representing the pole face regions and the other representing the inter-polar regions.
- The flux levels in the machine change depending on the rotor's position.
- The inductance changes with respect to the rotor angle.