DESIGN OF HYBRID-ELECTRIC VEHICLE ARCHITECTURES USING AUTO-GENERATION OF FEASIBLE DRIVING MODES

Several hybrid-electric vehicle architectures have been commercialized to serve different categories of vehicles and driving conditions. Such architectures can be optimally controlled by switching among driving modes, namely, the power distribution schemes in their planetary gear (PG) transmissions, in order to operate the vehicle in the most efficient regions of engine and motor maps. This paper proposes a systematic way to identify the optimal architecture for a given vehicle drive cycle, rather than parametrically optimizing one or more pre-selected architectures. An automatic generator of feasible driving modes for a given number of PGs is developed. For a powertrain consisting of one engine, two motors and two PGs, this generator results in 1116 modes. A heuristic search is then proposed to find a near-optimal pair of modes for a given driving cycle and vehicle specification. In a study this process identifies a dual-mode architecture with an 8 % improvement in fuel economy compared to a commercially available architecture over a standard drive cycle.

A sensitivity based heuristic for optimal blade arrangement in a linear mistuned rotor

This paper investigates methodologies for finding optimal or near-optimal blade arrangements in a bladed disk with inserted blades for minimizing or maximizing blade response amplification due to mistuning in material properties of the blades. The mistuning in the blades is considered to be known, and only their arrangement is modifiable. Hence, this is a problem in discrete optimization, particularly combinatorial optimization where the objective of response amplification is a nonlinear function of the blade arrangement. Previous studies have treated mistuning as a continuous parameter to analyze its effects on the response amplification. Sensitivity metrics have proven to be an important tool in quantifying the effects of mistuning. One such sensitivity metric is used here to formulate an iterative heuristic approach to solve the optimization problem. A component mode mistuning reduced order model is used for fast evaluations of the dynamic responses of a bladed disk with a given blade arrangement. At any iteration the sensitivity of the maximum response of the current rotor design to changes in blade stiffnesses due to changes in the blade arrangement is used to predict the arrangement for the following iteration. In addition to the proposed sensitivity-based approach, we use genetic algorithms to find optimal arrangements and compare results with the heuristic approach

Hybrid electric vehicle powertrain design: Construction of topologies and initial design schemes

This paper introduces the generic representation and construction methods for the architectures of the four-wheel-drive hybrid electric vehicle (HEV) powertrain, which achieve the unified rules to represent and construct all types of HEV powertrains. To map the architecture into numerical variables and add it into optimization, the kinematic matrix of the HEV powertrain is extracted corresponding to the topological structure. Based on the torque distribution requirement of four-wheel-drive HEV, the initial design schemes (architecture and parameters) are created by charge-under-go feasibility inspection