IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 66, NO. 6, JUNE 2019 4189 Development and Analysis of a New Hybrid Excitation Brushless DC Generator With Flux Modulation Effect Linnan Sun , Student Member, IEEE, Zhuoran Zhang , Senior Member, IEEE, Li Yu , Student Member, IEEE, and Xiangpei Gu Abstract—A new hybrid excitation brushless dc genera- tor (HEBLDCG) consisting of structure-parallel permanent magnet machine part and flux modulation machine part is proposed in this paper. Based on the flux modulation ef- fect, the permanent magnet machine and flux modulation machine parts, which have different operating principles, can be combined. In addition, the proposed HEBLDCG fea- tures a lower short-circuit current by regulating field cur- rent, which increases reliability. The operating modes of flux modulation machine part are fully analyzed under different conditions. Changes in the phase shift factor of the perma- nent magnet machine part caused by the operating modes of the flux modulation machine part are investigated. Fur- ther, the proposed HEBLDCG features constant voltage out- put at a wide range of speeds. Finally, a prototype HEBLDCG is designed and manufactured. The experimental data agree with the simulated data. Loss breakdown is analyzed and efficiency is measured. An HEBLDCG with a reliable diode rectifier is promising for application in on-board dc power generation systems. Index Terms—Brushless dc power generation system, flux modulation machine (FMM), hybrid excitation machine (HEM), operating mode, permanent magnet machine (PMM), phase shift factor (PSF). I. INTRODUCTION A BRUSHLESS dc power generation system is the core component of hybrid electric vehicles and more electric aircrafts. Hybrid excitation machines (HEMs) involving per- manent magnet (PM) and wound field (WF) excitation exhibit good flux regulation capability when regulating the field current, which simplifies the structure of the system and the methods Manuscript received January 22, 2018; revised April 3, 2018 and June 26, 2018; accepted July 23, 2018. Date of publication August 15, 2018; date of current version January 31, 2019. This work was supported in part by the National Natural Science Foundation for Excellent Young Scholar of China under Award 51622704, in part by Jiangsu Provin- cial Science Funds for Distinguished Young Scientists under Award BK20150033, in part by Funding for Outstanding Doctoral Dissertation in NUAA under Project BCXJ15-01, and in part by Foundation of Graduate Innovation Center in NUAA under Project kfjj20170307. (Corresponding author: Zhuoran Zhang.) The authors are with the Center for More-Electric-Aircraft Power System, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China (e-mail:, sunlinnan_nuaa@163.com; apsc-zzr@nuaa. edu.cn; yulipc@126.com; 153272201@qq.com). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TIE.2018.2864701 TABLE I COMBINATIONS OF PMMS AND WFMS used to control generation use [1] and [2]. Generally, HEMs can be divided into those with series and parallel topologies de- pending on the type of coupling of PM and WF excitation [3], [4]. Parallel HEMs (PHEM) [5]–[9] have improved flux regu- lation capacity since WF flux does not pass through PMs, thus avoiding the disadvantage of irreversible demagnetization risk of PMs, which exists in series HEMs [10], [11]. Structure PHEMs (SPHEMs), which consist of a PM ma- chine (PMM) part and a WF machine (WFM) part, exhibit the benefits of PHEMs and the negligible coupling of the PM and WF flux paths. Based on the location of the excitation source, PMMs can be divided into rotor-mounted PMMs and stator- mounted PMMs [12]. Similarly, WFMs can be categorized as rotor-wound WFMs, stator-wound WFMs, or reluctance ma- chines without independent field winding [13]. These categories can be combined in six ways, as shown in Ta- ble I. A hybrid excitation type synchronous machine with tradi- tional PMM and a wound rotor synchronous machine (WRSM) [14] belongs to the Type I. Prior experiments [15] show that the HEM exhibits good flux regulation. However, it is necessary for the WRSM to have a brush and slip ring, which shortens its oper- ating life and reduces the maintainability. In addition, brushless WRSM has a complicated rotor structure with a rotating recti- fier, which decreases reliability. Further, the unidirectional field current in this type of machine limits its flux regulation range. Combination of a PM and a reluctance motor with a two-part rotor proposed in [16] and [17] produces Type III. The double- stage rotor shares one stator and no independent field winding occurs. Flux can be regulated by the d-axis component of the ar- mature current. A controlled rectifier is required for generation use. 0278-0046 © 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications standards/publications/rights/index.html for more information. Authorized licensed use limited to: NANJING UNIVERSITY OF AERONAUTICS AND ASTRONAUTICS. Downloaded on March 23,2020 at 12:20:08 UTC from IEEE Xplore. Restrictions apply.