Torsional oscillations in the drivetrain of electric vehicles are an often observed phenomenon. They lead to an uncomfortable jerking of the vehicle and to material problems. Furthermore, thinking more and more about anti-slip control to increase the performance of electric vehicles, the damping of mechanical drivetrain oscillations becomes indispensable. In contrast to speed or even position controlled industrial electrical drives, traction drives in electric vehicles are purely torque controlled. As a consequence, the system damping cannot be increased by a simple adaptation of control parameters. The vehicle half shafts and the rotor inertia are responsible for the first system eigenfrequency with values not higher than 10 Hz. As a result, to influence the system's behavior the mechanical parameters of the half shafts and the rotor have to be changed, i.e. the stiffness and the damping factor of the haft shafts and the inertia of the rotor. As these parameters are difficult to vary by mechanical means, the electrical traction drive shall provide a torque component that leads to active damping. In the paper, the physical background of the active damping algorithms is described and their impact an the mechanical drivetrain is discussed and assessed. As most oscillations are excited by a change of the load, i.e. by the driver pressing the acceleration pedal, the idea of filtering the acceleration command also becomes interesting and, thus, is also discussed. However, most flexibility in damping drivetrain oscillations is reached by closed-loop active damping algorithms. There are two different types of algorithms that are preferred in this paper: the virtual damping factor and the virtual inertia. The functionality of these two active damping algorithms is verified by simulations based an a model of the electric vehicle drivetrain, which was verified by measurements of the half-shaft torque within an electric test vehicle. A comparison shows that the virtual damping factor is the best solution though an additional virtual rotor inertia can be used to further improve the system behavior.
Comparison of drivetrain-oscillation damping-algorithms for electric vehicles
Vergleich von Dämpfungs-Algorithmen für den Antriebsstrang elektrischer Fahrzeuge
2001
11 Seiten, 7 Bilder, 2 Tabellen, 10 Quellen
Aufsatz (Konferenz)
Datenträger
Englisch
Comparison of Drivetrain-Oscillation Damping-Algorithms for Electric Vehicles
British Library Conference Proceedings | 2001
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