Guo, H.J.

Ichinokura, O.

Kimura, M.

Onda, T.

Watanabe, T.

Yanada, T.

IEEE Transactions on Magnetics

English

application/pdf学術論文 (Article)296159 bytesjournal articl

Tohoku University Repository (TOUR) / 東北大学機関リポジトリ

IEEE TRANSACTIONS ON MAGNETICS, VOL 34, NO 4, JULY 1998 2147 Analysis of Dynamic Characteristics of Switched Reluctance Motor Based on SPICE 0. Ichinokura, T. Onda, M. Kunura, T. Watanabe, T. Yanada and H.J. Guo Dept. of Elect & Comm. Engng., Tohoku University, Sendai 980-77, JAPAN Abstract-A method for calculating the dynamic characteristics of Switched Reluctance Motor (SRM) has been proposed. The inductance model of SRM that is changed following the rotor position can be estimated from FEM analysis. Based on the model, we design a circuit simulation of SRM using SPICE, which can simulate voltages, currents, torque and rotation speed of the SRM In& term-Switched Reluctance Motor, Reluctance, Dynamic characteristics, Circuit simulation I . INTRUDOCTION WITCHED Reluctance Motor(SRM), using reluctance torque S which comes from the change of the relactance of magnetic circuit, can be thought of as a type of synchronous motor. However, compared with a regular synchronous motor, no field winding, slip ring and brush are used In addition, instead of using a permanent magnet, a pole configuration shaped by stacked-Si-Fe will be used as rotor. The SRM has desirable features including simple construction, high reliability and lower cost. Recently, following the development of power electronics, the interest in SRM has risen year after year [l], [2], even though it also has some bad perfonnance, for example, low power factor, large torque ripple and that the rotor position must be detected. However, analysis and optimum design have not been clarified fully [3]. A main reason for this is that it is dependent so much on experimental knowledge in making and controlling of a SRM. Thus, a computer-based simulation tool of SRM including a model of SMR and driving circuit will be useful in design of SRh4 and in the development of various control algorithms. In this paper, we present a method for calculation of dynamic characteristics of SRM. Based on the method, a computer simulation tool in order to analyze the dynamic characteristics of SRM also has been proposed. Because the reluctance of SRM is variable following the rotor position, the FEM analysis was applied to estimate the inductance depending on the rotor position. Then using inductance characteristics, an analysis model of SRM was constructed using a SPICE simulator. The calculation method will be discussed in section 2, the SPICE model will be found at section 3, and section 4 is conclusion. U .  RELUCTANCE ESTIMATION so we measure the output torque of SRM in order to verify the estimated reluctance. A. Reluctance Estimation using magnetic field analysis Fig.1 is the schematic diagram of a six-stator pole, four-rotor pole, three phase motor with phase A stator winding. Assume that the magnetic characteristics of the Si-Fe in both stator and rotor to be linear and that the motor shape is constant in axis direction. Let the relative permeability of Si-Fe be 3000 and the relative permeability of the winding part be 1. A FEM program, ANSYS, has been used to magnetic field analysis and the boundary condition of the vector potential at the outermost contact circle is set to be zero. Consider that only phase A has been excited when the rotor rotates 90 degree. The same magnetic circuit will be reconstructed due to the four-rotor pole. We assume the zero position as that when the center of both excited stator pole and the rotor pole just meet. Then we calculate the magnetic coenergy from 0 deg to 45 deg on 3 deg steps. It is well known that the magnetic coenergy and the reluctance has following relation where W’is magnetic coenergy, i is exciting current, L(Q) is reluctance and B is the position of rotor. So the reluctance can be obtained for every 3 degree from 0 to 45 degree. The result of the reluctance as a function of 8 in the case of i = 2 A is shown in Fig.2. It can be obtained from Fig.2 that the reluctance decreases with increasing 8 and after B = 33 deg, the reluctance appears constant. The outcome of flux density distribution at 8 = 24 deg is shown in Fig. 3. e+- ,- U The magnetic coenergy will be used to estimate the reluctance of SRM. The magnetic coenergy can be calculated from magnetic field analysis. But the magnetic coenergy can not be measured directly, Manuscript received October 13, 1997. Stator pole arc PS 30 deg. Rotor pole arc j3r 32 deg. Stack length 51 mm Number of windings I phase 72 turns Fig. 1 .  The structure of the SRh4 with parameters 0018-9464/98$10.00 0 1998 IEEE Authorized licensed use limited to: TOHOKU UNIVERSITY. Downloaded on October 8, 2008 at 00:45 from IEEE Xplore.  Restrictions apply.2148 B. Calculatzon of Torque To verify the estimated reluctance of SRM, the followng Using followng well-known relation, the torque can be indirect method is used calculated easily from magnetic coenergy. A SPICE model of SIiiM On the basis of inductance -rotor position charactenstics, we can construct a clrcuit analysis model of SRM using SPICE simulator [4] The SPICE model consists of a mam clrcuit and four sub- circuits that express vanable mductance, control signal, motor torque and equahon of motion The simulabon flow dagram between mam crrcuit and sub-cxcuit is shown in Fig 5 The main clrcmt is shown m Fig 6, m wluch LA, LB and L, are vanable mductances that represent the SRM, 6 andV, are the DC power sources, Q,,, . Qc2 are the bipolar transistors used as swtch, D,, , Dcz are the feedback &odes and RA, R, are the wmng resistances 1) Inductance sub-circuit The vanable mductance charactenstc shown m Fig2 wll  be represented by Founer senes, so the mductance sub-clrcuit can be smulated by a mulhplier of the signal source whch depends on the position of the rotor and standard mductance Lref such as shown m Fig 7 2) Motor torque sub-circuit: A current source can be used to represent the torque for each phase The total torque can be obtsuned by parallel cascade of each current source as shown in Fig 8 From the above relation, reluctance torque occurs if we tum on the excitation current when the rotor is in the position where the differentiation of reluctance is positive. Clearly the torque and the reluctance depend on 8 ,  and hence a rotor position detector is needed. The calculated value and the measured value of static torque under three values of exciting current is shown in Fig.4. D. DYNAMICAL CHARACTERISTIC ANALYSIS OF SRM USING SPICE MODEL - 3 30 Y U" 20 g 10 U .- U '0 IO 20 30 40 50 Rotor position [deg.] Fig.2. Variable Inductance as a hc t ion  of position Fig.3. FEM analysis result when 8 = 24deg 0.20 I I I I I 1 E Line: Calc. * 0.15 Symbol: Meas. d 0.05 0 k- Rotor position, 8 [deg.] Fig.4. The characteristics of static torque 1 50 Fig. 5. Simulation flow diagram I I I I I 1 I Fig.6. The main circuit of SRM model Fig.7. Inductance sub-circuit T Fig.8. Motor torque sub-circuit Authorized licensed use limited to: TOHOKU UNIVERSITY. Downloaded on October 8, 2008 at 00:45 from IEEE Xplore.  Restrictions apply.2149 - 6000 - E e- 2 4000 - h - I I 1 I I - \ - 9  -2 - h - h\ a - - 5 0 %\ \ g 2000- .- U - b - R i  I I I I I 3) Control signal sub-circuit: The control signal must turn on when the differentiation of inductance is positive and turn off when the differentiation of inductance is negative. The control signal is used to open and close the transistors, in order to keep continually rotating. We take the control signal as a current source in Fig.9. L Q  .... Emitter Q off Fig.9. Control signal sub-circuit Fig. 10. Equation of motion sub-circuit Phase Torque IV. CONCLUSION Toque INml n I I I 1 Tlms[msecl .- Pnase TOW,. -0 2 I 0' I I Fig. 1 1, The results of dynamical characteristic of SRM A use l l  simulation method used to analyze the dynamical characteristic of SRM has been presented. The key point is to estimate the reluctance of SRM. Because the result of proposed estimation method is certified well by experiments(see Fig.4), the proposed method is believed appropriate. Using the simulation tool, we can consistently design SRM from calculating the characteristics to evaluating performance. As a future work, we will use the simulation tool to design some real SRM and measure their dynamical characteristics in order to improve our method and develop some excellent control algorithms. REFRENCES [l] T.A. Lip0 and Yue Li, "The CFM-A New Family of Electrical Machines," Proceeding of International Power Electronics Conference, pp. 1-9, 1995. [2] D.A. Staton, W.L. Soong and T.J. Miller, "Unified Theory of Torque Production in Switched Reluctance and Synchronous Reluctance Motors," IEEE Transactions on Industry Applications, vo1.3 1, No.2, pp. 329-337, 1995. [3] R.C. Becerra, M. Ehsani and T.J E. Miller, "Commutation of SR Motors," E E E  Transactions on Power Electronics, vo1.8, No.3, [4] The Design Center Circuit Analysis-Application Notes Manual, pp. 257-263, 1993. MicroSim Corporation, 1995. Authorized licensed use limited to: TOHOKU UNIVERSITY. Downloaded on October 8, 2008 at 00:45 from IEEE Xplore.  Restrictions apply.

Analysis of Dynamic Characteristics of Switched Reluctance Motor Based on SPICE

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Analysis of Dynamic Characteristics of Switched Reluctance Motor Based on SPICE

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