Abstract
In order to increase the torque density of the fivephase machines, the third harmonic is commonly employed. In this paper, the optimal and critical ratios for the third harmonic current injection are analytically derived and validated by finite element (FE) analyses. It is found that the optimal and critical injection ratios along with the torque improvement are dependent on the ratio of the third harmonic back electromotive force to the fundamental one. In order to improve the electromagnetic torque contributed by the third harmonic component, this paper employs unequal tooth to increase both the fundamental and third harmonic winding factors. Meanwhile, the optimal unequal tooth width combination is deduced and demonstrated by the FE method. When the third harmonic current is injected under the same amplitude constraint, the output torque can be improved. When the third harmonic current is injected under the same RMS value constraint, for the ten-slot/eight-pole equal tooth machine, the output torque can barely be increased, whilst for the unequal tooth machine, the output torque can be increased by 2.1%. Finally, the ten-slot/eightpole machine with unequal teeth is prototyped and tested to prove the analyses.
| Original language | English |
|---|---|
| Article number | 8103333 |
| Pages (from-to) | 206-215 |
| Number of pages | 10 |
| Journal | IEEE Transactions on Vehicular Technology |
| Volume | 67 |
| Issue number | 1 |
| Early online date | 10 Nov 2017 |
| DOIs | |
| Publication status | Published - 1 Jan 2018 |
Funding
Manuscript received March 14, 2017; revised July 5, 2017 and September 7, 2017; accepted October 14, 2017. Date of publication November 10, 2017; date of current version January 15, 2018. This work was supported in part by the National Natural Science Foundation of China under Project 51607089 and 51407093, in part by the Natural Science Foundation of Jiangsu Province under Project BK20150744 and BK20140814, and in part by the Fundamental Research Funds for the Central Universities under Grant NE2016003. The review of this paper was coordinated by the Guest Editors of the VPPC 2016 Special Section. (Corresponding author: K. Wang.) Z. Gu, K. Wang, C. Liu, and R. Cao are with the College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China (e-mail: [email protected]; [email protected]; lc@ nuaa.edu.cn; [email protected]).
Keywords
- Multi-phase machine
- SPM machine
- Third harmonic injection
- Unequal tooth structure
ASJC Scopus subject areas
- Automotive Engineering
- Aerospace Engineering
- Computer Networks and Communications
- Electrical and Electronic Engineering