Novel Direct Flux and Torque Control of Optimally Designed 6 Phase Reluctance Machine with Special Current Waveform

Authors: E T. Rakgati, E. Matlotse

Abstract:

In this paper the principle, basic torque theory and design optimisation of a six-phase reluctance dc machine are considered. A trapezoidal phase current waveform for the machine drive is proposed and evaluated to minimise ripple torque. Low cost normal laminated salient-pole rotors with and without slits and chamfered poles are investigated. The six-phase machine is optimised in multi-dimensions by linking the finite-element analysis method directly with an optimisation algorithm; the objective function is to maximise the torque per copper losses of the machine. The armature reaction effect is investigated in detail and found to be severe. The measured and calculated torque performances of a 35 kW optimum designed six-phase reluctance dc machine drive are presented.

Keywords: Reluctance dc machine, current waveform, design optimisation, finite element analysis, armature reaction effect.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1085748

References:

[1] Weh H.: "Zur Weiterentwicklung wechselrichter-gespeister reluktanzmaschinen fur hohe leistungs-dichten und grobe leistung", ETZ Archiv, 1984, Vol. 6, No.4, pp. 135-141.
[2] Weh H. and Schroder U.: "Static inverter concepts for multiphase machines with square-wave current field distributions", European Power Electronic Conference (Brussels), 1985, pp. 1147-1152.
[3] Boldea I. and Nasar S.A.: "Emerging electric machines with axially laminated anisotropic rotors: A review", Electric Machines and Power systems, 1991, Vol. 19, pp. 673 - 701.
[4] Toliyat H.A, Xu L and Lipo T.A, "A five-phase reluctance motor with high specific torque", IEEE Transactions on IAS, Vol. 28, pp. 659 - 667, no.3, May/June 1992.
[5] Xu L, "Rotor structure selections of non-sine five-phase synchronous reluctance machines for improved torque capability", IEEE Transactions on IAS, vol. 36, no.4, pp. 1111 - 1117, July/August 1992.
[6] Toliyat H.A, Waikar P.S. and Lipo T.A, "Analysis and simulation of five phase synchronous reluctance machines including third harmonic of airgap MMF", IEEE Transactions on IAS, vol. 34, no.2, pp. 332 - 339, March/April 1998.
[7] Xu L and Fu W.N, "Evaluation of 3rd harmonic component effects in 5- phase synchronous reluctance motor drive using time stepping finite element method", IEEE IAS Conf. record , 2000, pp. 1- 8.
[8] Toliyat H.A, Shi R and Xu H, "A DSP-based vector control of fivephase synchronous reluctance motor", IEEE IAS Conf. record , 2000, pp. 1- 7.
[9] Bomela X.B., Kamper M.J.: "Effect of stator chording and rotor skewing on performance of reluctance synchronous machine", IEEE Trans. Ind. Appl. Soc. (IAS), vol. 38, no. 1, pp. 91-100, Jan. 2002.
[10] Abdel-Razek A.A., Coulomb J.L., Feliachi M. and Sabonnadiere J.C.: "The calculation of the electromagnetic torque in saturated electric machines within combined numerical and analytical solutions in the field equations", IEEE Trans. on Magnetics, vol. 17, no. 6, pp. 3250- 3252, Nov. 1981.
[11] Powell M.J.D.: "An efficient method for finding the minimum of a function of several variables without calculating derivatives", Computer Journal, 1964, vol. 7, pp. 155-162.
[12] Rakgati E.T and Kamper M.J, "Torque performance of optimally designed three and five-phase reluctance synchronous machines with two rotor structures", Trans. SAIEE, on printing Dec. 2006.
[13] Thompson S.P.: "Dynamo electric machinery", M. Strong (New York, N.Y.), eighth edition, pp. 389 (Fig. 264), 1911.
[14] Manjrek M.D, Steimer P.K and Lipo T.A: "High multilevel power conversion system: A competitive solution for high power applications", IEEE Transactions on IAS, vol. 36, no.3, pp. 834- 841, May/June 2000.