Component control for the Zero Inertia powertrain

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Multiobjective control : an overview

An overview of a number of approaches to the multiobjective control problem is given. In practice, this problem usually boils down to a mixed-norm optimization, where traditionally the norms of interest are H2, H8 and l1. To capture different, often conflicting, design specifications a single-norm form is usually not enough and therefore a mixed-norm formalism combining these norms would be of considerable interest. Although it would be nice to have all three norms present, most approaches focus on the two-norm problem. Frequently encountered is the H2/H8 mixed-norm optimization problem, but combinations of l1 and the other two norms are starting to get more attention. It will be seen that the solution to the mixed-norm optimization problem has not yet reached a final shape, since most methods still exhibit problems, like not being able to find a solution if performance specifications are tight, or generating high-order or too conservative controllers, et

Control of a continuously variable transmission in an experimental vehicle

This paper focusses on the development of a component controllerfor a hydraulically actuated metal push-belt Continuously Variable Transmission(CVT), using models for the mechanical and the hydraulic part of the CVT. Theratio controller guarantees that one clamping pressure setpoint is minimal, whilethe other is raised above the minimum level to enable shifting. This approach is beneficial with respect to efficiency and wear. Vehicle experiments show that goodtracking is obtained. The largest deviations from the ratio setpoint are caused by hardware limitations

Optimal energy management for a flywheel-based hybrid vehicle

This paper presents the modeling and design of an optimal Energy Management Strategy (EMS) for a flywheel-based hybrid vehicle, that does not use any electrical motor/generator, or a battery, for its hybrid functionalities. The hybrid drive train consists of only low-cost components, such as a flywheel module and a continuously variable transmission. This hybrid drive train is characterized by a relatively small energy capacity (flywheel) and discrete shifts between operation modes, due to the use of clutches. The main design criterion of the optimized EMS is the minimization of the overall fuel consumption, over a pre-defined driving cycle. In addition, comfort criteria are formulated as constraints, e.g., to avoid high-frequent shifting between driving modes. The criteria are used to find the optimal sequence of driving modes and the generated engine torque. Simulations show a fuel saving potential of 20% to 39%, dependent on the chosen driving cycle

The Empact CVT: modeling, simulation and experiments

This paper shows the implementation of a simulation model for newelectromechanically actuated metal V-belt type continuously variabletransmission (CVT), referred to as the Empact CVT. An analysis ofthe dynamics of the actuation system and of the driveline shows thatthe eigenfrequencies of the system depend on both the CVT ratio andthe slip in the variator. An accurate variator model is required to incorporateall characteristic dynamics. The implemented variator modelis an explicit formulation of a model which gives an estimation of thetension forces and compression forces in the pushbelt. The simulationmodel also includes slip, shifting losses based on transient variator modelsand friction. Simulations are compared to measurements, showinggood results

Multiobjective control : an overview

An overview of a number of approaches to the multiobjective control problem is given. In practice, this problem usually boils down to a mixed-norm optimization, where traditionally the norms of interest are H2, H8 and l1. To capture different, often conflicting, design specifications a single-norm form is usually not enough and therefore a mixed-norm formalism combining these norms would be of considerable interest. Although it would be nice to have all three norms present, most approaches focus on the two-norm problem. Frequently encountered is the H2/H8 mixed-norm optimization problem, but combinations of l1 and the other two norms are starting to get more attention. It will be seen that the solution to the mixed-norm optimization problem has not yet reached a final shape, since most methods still exhibit problems, like not being able to find a solution if performance specifications are tight, or generating high-order or too conservative controllers, et

Hierarchical control of the Zero Inertia powertrain

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

A new CVT powertrain without jet start behaviour : analysis of design, dynamics and control

Due to rotating inertias within the engine and transmission, the response of a vehicle during large engine speed shifts may appear reluctant or even counteracting. Reminiscent of comparable behaviour seen in aircraft jet-propulsion, this phenomenon is also referred to as 'jet-start'. To overcome this behaviour, a CVT powertrain is augmented with a planetary gear set and compact steel ywheel. The new transmission seamlessly combines two contradictory features: the driveability in terms of the pedal-to-wheel response is greatly improved and a large leap towards optimal fuel economy can be made. This is achieved by cruising the vehicle at extremely low engine speeds, using the large ratio-coverage of the CVT. The ywheel acts as a 'peak shaver' during speed shifts: it delivers power during engine acceleration and absorbs kinetic energy during engine decelerations. In this paper, optimal design, system dynamics and control aspects of the new powertrain are discussed