Non-linear analysis of advanced high-phase number induction machines for adjustable speed drive applications

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references (leaves 147-151).Issued also on microfiche from Lange Micrographics.This study focuses on the effect of high order phases on electrical machines' parameters and performance. A general approach has been conducted using the induction motor equivalent circuit, winding function and conventional design methods. This approach was supported with finite element analysis. The study shows that high order phase machines have higher peak torque than the equivalent three phase machines. This is attributed to the lower leakage inductance that decreases as the number of phases increases. However, the peak slip frequency increases causing an increase in the skin effect and losses of the rotor. Some design suggestions are proposed to resolve this issue. The conducted harmonic analysis shows that high order harmonics (3rd, 5th, ..) that generate pulsating torque in the three phase machine can be used in high order phase machines to generate torque. For this purpose, a multiphase coordinate transformation and a revised dq model of the five phase induction motor under the fundamental and third harm,monic currents are established in a newly defined d₁q₁d₃q₃n reference frame. An extensive analysis using the finite element package has been conducted to compare the performance of different machines when supplied with quasi-rectangular currents with concentrated windings. From torque per ampere point of view, five-phase machine shows an outstanding performance compared with other machines. Futhermore, additional analysis has been conducted for the five-phase and three-phase machines when supplied with sinusoidal voltage source. Experiments have been performed on a 7.5hp five-phase induction motor using TMS320C32 DSP to systematically test and compare stator tooth flux densities and torques in the presence and absence of third harmonic currents. The results obtained are consistent with theoretical studies and simulation analysis, which further demonstrate the feasibility and practical significance of the high-order phase machines