Hierarchical control of the Zero Inertia powertrain

Abstract A vehicular powertrain incorporating a continuously variable transmission (CVT) and a flywheel is considered and divided into a number of system layers with descending response times. Among these layers are the electronic circuits supplying the control currents, solenoids controlling the CVT pulley pressures, the engine throttle valve, the CVT, the engine, and finally the vehicle. Figure 2 in Section 1 will illustrate the system layers and their interaction in more detail. In view of the system layer hierarchy, a hierarchical—or cascaded—control scheme is introduced, simplifying the total control design. Such an approach is justified if the operation of each layer can be described independently of the rest of the system, i.e., the faster layer can be assumed static with respect to the slower one (Singular Perturbation Methods in Control: Analysis and Design, Academic Press, New York, 1986, p. 1). This assumption does not appear to be appropriate for all layers, though not insurmountable in practice. The new Zero Inertia powertrain, control hierarchy and the results from simulations and various experiments are discussed in the paper.