Optimal Current Control of Externally Excited Synchronous Machines in Automotive Traction Drive Applications

The excellent suitability of the externally excited synchronous
machine (EESM) in automotive traction drive applications
is justified by its high efficiency over the whole operation range and
the high availability of materials. Usually, maximum efficiency is
obtained by modelling each single loss and minimizing the sum of all
losses. As a result, the quality of the optimization highly depends on
the precision of the model. Moreover, it requires accurate knowledge
of the saturation dependent machine inductances. Therefore, the
present contribution proposes a method to minimize the overall losses
of a salient pole EESM and its inverter in steady state operation based
on measurement data only. Since this method does not require any
manufacturer data, it is well suited for an automated measurement
data evaluation and inverter parametrization. The field oriented control
(FOC) of an EESM provides three current components resp. three
degrees of freedom (DOF). An analytic minimization of the copper
losses in the stator and the rotor (assuming constant inductances) is
performed and serves as a first approximation of how to choose the
optimal current reference values. After a numeric offline minimization
of the overall losses based on measurement data the results are
compared to a control strategy that satisfies cos (ϕ) = 1.

• Oliver Haala
• Bernhard Wagner
• Maximilian Hofmann
• Martin Marz

• Current control
• efficiency
• externally excited synchronous machine
• optimization.

<p>[1] J. Santiago, H. Bernhoff, B. Ekergard, S. Eriksson, S. Ferhatovic, R. Waters,
M. Leijon, Electrical Motor Drivelines in Commercial All-Electric
Vehicles: A Review, IEEE Transactions on vehicular technology, vol. 61,
no. 2, February 2012.
[2] M. M¨argner, W. Hackmann, Control challenges of an externally excited
synchronous machine in an automotive traction drive application, Emobility
- Electrical Power Train, November 2010.
[3] M. Niemel¨a, Position sensorless electrically excited synchronous motor
drive for an industrial use based on direct flux linkage and torque control,
PhD thesis, Lappeenranta University of Technology, Finnland, 1999.
[4] I. Boldea, G. Andreescu, C. Rossi, A. Pilati, D. Casadei Active Flux Based
Motion-Sensorless Vector Control of DC-Excited Synchronous Machines,
Energy Conversion Congress and Exposition, September 2009.
[5] A. Girardin, G. Friedrich, Optimal control for a Wound Rotor Synchronous
starter generator, Industry Applications Conference, October
2006.
[6] R. Grune, Verlustoptimaler Betrieb einer elektrisch erregten Synchronmaschine
f¨ur den Einsatz in Elektrofahrzeugen, PhD thesis, Technische
Universit¨at Berlin, Germany, 2012.
[7] H. Karmaker, Stray losses in large synchronous machines, IEEE Transactions
on Energy Conversion, vol. 7. no. 1, March 1992.
[8] K. Kanelis, Die feldorientierte Kennliniensteuerung der stromerregten
Synchronmaschine , PhD thesis, Universit¨at der Bundeswehr M¨unchen,
Germany, 1994.
[9] K. H. Bayer, H. Waldmann, M. Weibelzahl Die Transvector-Regelung f¨ur
den feldorientierten Betrieb einer Synchronmaschine, Siemens Zeitschrift,
Heft 10, 1972.</p>