一种新型两相励磁开关磁阻电机驱动系统的静态特性

第22卷第12期中国电机工程学报Vol.22 No.12 Dec. 2002

2002年12月Proceedings of the CSEE©2002 Chin.Soc.for Elec.Eng.文章编号

华中科技大学

STATIC PERFORMANCE OF A NEW SRD SYSTEM WITH

TWO-PHASE EXCITATION

GUO Wei, ZHAN Qiong-hua, QIU Yi-hui

(Huazhong University of Science and Technology, Wuhan 430074, china)

ABSTRACT: This paper provides an analysis of a switched

reluctance motor (SRM) under two-phase excitation. After a

brief introduction of the two-phase excitation scheme, the flux

linkage model of a SRM under two-phase excitation is

developed using FEA. A linearized model is then established

based on the detailed flux linkage analysis. The torque-angle

characteristics of such a linear model are compared with that

derived from the detailed and nonlinear FEA model. Based on

the FEA model, an optimized control strategy is proposed to

improve the performance of the SRM under two-phase

excitation.

KEY WORDS: switched reluctance motor; torque ripple; two-

phase excitation

摘要

SRMÎÄÖÐÊ×ÏȼòÒª½éÉÜÁËÕâÖÖÁ½ÏàÀø´ÅϵͳµÄ½á¹¹»ùÓÚÏêϸµÄ·ÇÏßÐÔÓÐÏÞÔª·ÖÎö的结果

并和非线性FEA模型下的结果进行了比较

根据FEA的结果

关键词转矩波动

TM352 文献标识码

国家科技部

中的专题

１

1

(a) SRM (b) AC motor

图１ 用于SRM和AC电机的功率开关的对比

Fig. 1 Power switch for SRM and AC motor

most often used SRD power converter topology. The power switch and the freewheeling diode in a typical SRD power converter are connected in series as shown in Fig.1 (a) while in the power switch modules for 3-phase AC motor drives they are connected in parallel as Fig.1 (b) shows. Since SRD systems are not widely used in industry, the power

92中 国 电 机 工 程 学 报第22卷

semiconductor manufacturers have no interest to manufacture the power modules suitable for SRD systems in large quantity, which means much higher cost for SRD power converter than the comparable one for AC motor and further weakens the competitiveness of SRD systems.

To overcome this problem, a novel topology of SRD power converter was proposed by Ahn et. Al, in which the conventional three phase inverters for AC drive is used for SRM [5], shown as Fig.2. of such a system. Each phase winding is wound in the reverse direction to the opposite side poles and three phases are Y connected. In addition, the authors proposed a new two-phase excitation (TPE) mode to decrease the acoustic noise by reducing the radial magnetic attractions during magnetizing and demagnetizing.TPE mode excites two phases simultaneously. One phase keeps working while the other two phases commutates. So the abrupt change of magnetization and demagnetization is decreased and so is the a b

c

a ′

b ′

c ′Although the principle analysis of the new topology in [1], basing on a linear model under many assumptions, is quite useful to introduce the concept, it can’t depict the details of the electromagnetic process in the machine, especially when mutual inductance also contributes to toque under TPE mode.Moreover, Ref [1] di

d not show how self and mutual inductances in th

e linear model could be obtained.

In this paper, we try to get some improvements based on the work reported in [1]. We first derive flux linkage model for a SRM under TPE using FEA.Then, we extract self and mutual inductances from the

flux linkage model and use them in a linear model to predict the torque-angle characteristics of SRM under TPE. Afterwards, we derive the torque-angle characteristics from the detailed FEA model and compare that with the one in linear model. Using FEA model analysis, we demonstrate that a phase

advance control can significantly increase average torque and attenuate torque ripple. The paper is concluded with a summary of main observations and suggestions for future work in this area.

2 MAGNETIC ANALYSIS OF THE PROFILES OF SELF-INDUCTANCE AND MUTUAL-INDUCTANCE

The self inductance flux linkage

As a doubly salient motor, the inductances of SRM are highly nonlinear function of current and rotor position. Using the flux linkage to analyze the performance of the motor under TPE may be better than using the inductance. So we first derive the flux linkage model for a SRM under TPE using FEA.

Considering the coupling effect between windings, the total flux linkage of a phase, for example phase A, is generated by all phases, shown as following

),,,(c b a a θψψi i i = (1)And the flux linkage of one phase is also a nonlinear function of all phase-currents and rotor position. For convenience, we define: the part of flux linkage of phase A, which is generated by phase A current i a , is named self-inductance flux linkage of phase A Ψaa while the part derived from phase B/C current i a/c , is named the mutual inductance flux linkage Ψab/ac .

In order to obtain the self inductance flux linkage Ψaa , i a and rotor position θ are set as independent variables and i b = i c =0

1