Yliopiston kampusalue HYBRID EXCITATION SYNCHRONOUS MACHINES (HESMs) FOR ISLAND OPERATION Katteden Kamiev Janne Nerg Juha Pyrhönen CONTENTS • Introduction • Classification • Mechanical Considerations • Radial Flux Machines • Example Machine • Finite Element Analysis • Conclusion • References INTRODUCTION Boundary conditions set e.g. by the marine classification societies • The generator voltage must remain within ±10% in all cases • The generator sustainable short circuit current must be three time the rated current at least for two seconds Short circuit current depends on the induced voltage and the direct axis inductance I sc,pu = Ef,pu Ld,pu = 3 ⋅ I n,pu , where Ef,pu is the induced per unit voltage and Ld,pu is the per unit synchronous inductance. CLASSIFICATION of HESMs Combining excitation sources • series hybrid excitation • parallel hybrid excitation Locations of PMs and excitation coils Classification of HESMs PM+EW PMs in the Rotor EW in the Rotor (Brushes/ Brushless) EW in the Stator (Brushless) PMs in the Stator EW in the Machine’s End (Brushless) EW in the Stator (Brushless) Classification of HESMs PMs and excitation coils are located on the rotor side. - Synchronous/Permanent Magnet Hybrid AC Machine Combination Rotor Hybrid Excitation Machine (CRHE) Classification of HESMs PMs are in the rotor and excitation coils are in the stator.  Consequent Pole PM Hybrid Excitation Machine (CPPM) PMs are in the rotor side and excitation coils are in the machine’s end.  Hybrid Excitation Machine with Powered Iron Core PMs and excitation coils are in the stator.  Hybrid Excitation Doubly Salient Machine Classification of HESMs Operation Principle Applications HESM has two excitation sources. One is the PM source that provides the airgap with constant flux and the other one is the EW (DC current) that acts as the flux regulator to adjust the air gap flux distribution. • as a generator it may be used in an island operation (alp, island, ship, etc.) • as a motor HESM is attractive for traction applications, for example, in electric, hybrid electric and fuel cell vehicles Special Features • two excitation sources which can be connected either in series or in parallel • location of PMs and excitation coils • bi-directional DC current Mechanical Considerations Advantages of radial flux vs. axial flux construction • The rotor of a radial flux machine may be more rugged than the rotor of an axial flux machine • Ideally, radial flux machine produces no axial forces • Radial flux machine is easier to cool as the rotor can in some cases be built as hollow • Damper winding is easier to arrange in a radial flux machine • The radial flux rotor dimensions may easily be adjusted to produce a suitable inertia for the prime mover Radial Flux Machines The advantages of the SPM vs VPM SPM - Utilizes the PM material best - Magnets mechanically vulnerable - Damper winding construction is complicated - Low volume of magnets because of only small magnet stray flux - Good damper properties VPM - High air gap flux density - High efficiency a) b) c) - High armature reaction - Mechanically rugged - Higher magnet stray losses → increase the volume of magnets d) e) f) → higher magnet price - Good damper properties Different rotor constructions of radial flux machines. (a) Rotor-surface-mounted magnets, (b) magnets embedded in the surface, (c) pole shoe rotor, (d) tangentially embedded magnets, (e) radially embedded magnets, (f) two magnets per pole in the V position. EXAMPLE MACHINE Structure Design specifications Cross-section view Main geometry data Parameter Value Unit Parameter Value Unit Phase number, m 3 - 750 mm Nominal power, Pn 400 kW Air gap diameter, Ds Length, l 400 mm Nominal voltage, Un 400 V Nominal current, In 725 A Number of PMs per pole 2 - Power factor, cosφ 0.8 - Rotational speed, n 750 rpm Frequency, f 50 Hz Number of pole pairs, p 4 - EXAMPLE MACHINE Operation Principal PM EW N S S N N N S S S N N S Magnetic flux paths due to PMs (blue lines) and excitation coils (red lines) Magnetic path of the PM flux: N pole of the PM → PM pole body → air gap → stator tooth → stator yoke → stator tooth → air gap → PM/EW pole body → S pole of the neighbour PM/own pole to form a loop. Magnetic path of the flux due to the electric excitation: pole of the electric excitation → S pole of the neighbour PM → PM pole → air gap → stator tooth → stator yoke → stator tooth → air gap → electrically excited pole to form a loop. E = EPM + Ef Finite Element Analysis Flux lines of the HESM Positive excitation current Zero excitation current Finite Element Analysis 600 1 Positive DC Zero DC Negative DC 400 Positive DC Zero DC Negative DC 0.8 200 Normal flux density [T] Induced phase voltage [V] 0.6 0 -200 0.4 0.2 0 -0.2 -0.4 -0.6 -400 -0.8 -600 0 0.002 0.004 0.006 0.008 t [s] 0.01 0.012 0.014 0.016 Armature winding EMF waveforms -1 0 100 200 300 400 500 x [mm] 600 700 800 Air gap flux density distributions Finite Element Analysis Short-circuit current as a function of time CONCLUSION HESMs - combine advantages of PM machines and traditional synchronous machines - have different constructions - have good flux control capability - can increase the short-circuit current REFERENCES . Hybrid Excitation Synchronous Machines: Energy-Efficient Solution for Vehicles Propulsion Amara, Y.; Vido, L.; Gabsi, M.; Hoang, E.; Hamid Ben Ahmed, A.; Lecrivain, M.; Vehicular Technology, IEEE Transactions on Volume 58, Issue 5, Jun 2009 Page(s):2137 - 2149 Digital Object Identifier 10.1109/TVT.2008.2009306 . Direct control of air-gap flux in permanent-magnet machines J. S. Hsu, IEEE Trans. Energy Convers., vol. 15, no. 4, pp. 361–365,Dec. 2000. . A new axial flux surface mounted permanent magnet machine capable of field control M. Aydin, S. Huang, and T. A. Lipo, in Conf. Rec. IEEE IAS Annu. Meeting, 2002, vol. 2, pp. 1250–1257. . A synchronous/permanent magnet hybrid AC machine Xiaogang Luo; Lipo, T.A.;Energy Conversion, IEEE Transaction on Volume 15, Issue 2, June 2000 Page(s):203 - 210 Digital Object Identifier 10.1109/60.867001 . Trial production of a hybrid excitation type synchronous machine N. Naoe and T. Fukami, Electric Machines and Drives Conference, 2001. IEMDC 2001. IEEE International, pp. 545-547,2001. REFERENCES . Design and test of permanent magnet synchronous motor with auxiliary excitation winding for electric vehicle application G. Henneberger, J. R. Hadji-Minaglou, and R. C. Ciorba Proc. Eur. Power Electron. Chapter Symp., Lausanne, Switzerland, Oct. 1994, pp. 645–649. . A double excited synchronous machine for direct drive application - Design and prototype tests D. Fodorean, A. Djerdir, I. A. Viorel, and A. Miraoui, IEEE Trans. Energy Convers., vol. 22, no. 3, pp. 656–665, Sep. 2007. . Consequent-pole permanent-magnet machine with extended field-weakening capability Tapia, J.A.; Leonardi, F.; Lipo, T.A.; Industry Applications, IEEE Transactions on Volume 39, Issue 6, Nov.-Dec. 2003 Page(s):1704 - 1709 Digital Object Identifier 10.1109/TIA.2003.818993 . Hybrid excitation machines with powdered iron core for electrical traction drive applications Kosaka, T.; Matsui, N.; Electrical Machines and Systems, 2008. ICEMS 2008. International Conference on 17-20 Oct. 2008 Page(s):2974 – 2979 . Static characteristics of a novel hybrid excitation doubly salient machine Chen Zhihui; Sun Yaping; Yan Yangguang; Electrical Machines and Systems, 2005. ICEMS 2005. Proceedings of the Eighth International Conference on Volume 1, 27-29 Sept. 2005 Page(s):718 - 721 Vol. 1 THANK YOU!