Effects of Electric Circulation on the Energy Efficiency of the Power Split e-CVT Hybrid Systems

Abstract

This paper aims at investigating the fundamental characteristics of energy efficiency for power split electronic-continuously-variable-transmission (e-CVT) hybrid systems under the operation of electric circulation, i.e., circulating part of the engine power through the generator and motor in form of electric energy to improve system efficiency as well as perform the continuously-variable-transmission (CVT) functionality. The relations of kinematics and energy conservation for each power component are constructed and analyzed to classify how the operating points of the engine in term of torque and rotational speed may vary under different degrees of electric circulation indicated by a parameter called ratio of circulating power. Thereby, power split e-CVT hybrid systems can be classified into three types: upward circulation, downward circulation, and neutral circulation. Accordingly, two power split e-CVT hybrid systems, one of input split type and the other of output split type, are selected to be analyzed regarding their operating characteristics and simulated on their performances of energy efficiency. As a result, the former is a type of downward circulation in favor of driving at low speed and high driving load, while the latter is a type of upward circulation with an advantage of driving at high speed and low driving load. Thereby, applying this analysis to investigate the effects of electric circulation on power split e-CVT systems may help the developers implement suitable energy management and control strategy in accordance with their corresponding operating characteristics of energy efficiency.

Turbocompound Power Unit Modelling for a Supercapacitor-Based Series Hybrid Vehicle Application

“…The corresponding m  values obtained combining Equations (6), (7) and (9) are reported with red rhombi in Figure 3. One can note that the m  values obtained with the proposed process are in accordance with the values shown in [37].…”

“…The increasing interest in sustainable mobility has led to the study and development of new hybrid architectures, which can be mainly divided in three main categories [1]: parallel [2][3][4][5][6], series/parallel (also known as power-split) [6][7][8][9][10][11][12][13][14], and series hybrid [15][16][17][18][19][20][21]. Passalacqua et al [22] proposed a new series architecture configuration for medium size cars, with a storage system based only on supercapacitors and they highlighted the benefits in terms of internal combustion engine (ICE) optimal working points.…”

Analytical Modeling and Comparison of Two Consequent-Pole Magnetic-Geared Machines for Hybrid Electric Vehicles

“…Additionally, the battery can be charged under a regenerative braking state. The concept that a PMSM is added after the CP-MGM is derived from that in E-CVT [33]. The PMSM in Figure 1 is used to regulate the performances of the outer rotor.…”

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“…A 200kW engine is selected with the functional expressions of engine torque, engine power, and BSFC shown in Eqs. (1), (2), and (3). The operation range of engine is designated by the constraint of engine output torque.…”

“…The automobile emission standards have become more stringent due to energy crisis and environmental problems in the past few years [1]. Many researches focused on the optimal energy management of internal combustion engine vehicles including conventional diesel/gasoline vehicles and hybrid electric vehicles were undertaken and documented [2,3]. The energy efficiency performances of vehicles are closely correlated to either driving patterns or steering behaviors.…”