Transient response and frequency domain analysis of an electrically variable transmission

Abstract

This article deals with the dynamic behavior of a passenger car equipped with an electrically variable transmission, which is analyzed both in time and frequency domains. After deriving the dynamic equations in the state-space form for both open-and closed-loop systems, a methodology for objectively evaluating the drivability of this over-actuated system is proposed. Several simulation results are presented with the aim of highlighting the transient response to fast engine torque changes and the effect of the generator speed controller calibration on the system dynamics. Moreover, the influence of the ratio between electrical and thermal power on the frequency response is discussed. The proposed analysis, which is based on a simple static torque split between internal combustion engine and propulsion electric motor, depicts the dynamic signature of the electrically variable transmission powertrain system, without any additional drivability filter. Hence, these results can constitute the base for the design of dynamic torque splitting aimed at optimizing the longitudinal vehicle response to the driver's acceleration demand.

Energy Management Strategy for Hybrid Multimode Powertrains: Influence of Inertial Properties and Road Inclination

“…The series-parallel incorporates the characteristics of both the series and parallel configurations, but including an additional mechanical link compared with the series architecture and an additional generator compared with the parallel architecture. The power-split category represents the most attractive solution due to its multimode and flexible nature which guarantees an adaptive solution to every vehicle working condition and fully realizes the powertrain potential to achieve both better fuel economy and improved drivability [12,13].…”

“…Zhuang et al [16] prove that three or more PGS do not lead to a significant fuel economy improvement with respect to the two PGSs configuration, thus justifying the low number of hybrid powertrains with three PGSs introduced in the automotive market. The second point is the most crucial, since the strategy to control the energy flow among these multiple sources, generally named "Energy Management Systems" (EMS), should try to minimize fuel consumption without compromising the smoothness and responsiveness of the vehicle, usually referred to as drivability, as shown by Galvagno et al [13]. According to the literature review, the most accredited EMS can be classified into two categories [17,18]: rule-based and optimization-based strategies.…”