An Adaptive-Equivalent Consumption Minimum Strategy for an Extended-Range Electric Bus Based on Target Driving Cycle Generation

Abstract

Energy management strategies based on instantaneous optimization have been widely used in hybrid/plug-in hybrid electric vehicles (HEV/PHEV) in order to improve fuel economy while guaranteeing vehicle performance. In this study, an adaptive-equivalent consumption minimum strategy (A-ECMS) based on target driving cycle (TDC) generation was proposed for an extended-range electric bus (E-REB) operating on fixed routes. Firstly, a Hamilton function and a co-state equation for E-REB were determined according to the Pontryagin Minimum Principle (PMP). Then a series of TDCs were generated using Markov chain, and the optimal solutions under different initial state of charges (SOCs) were obtained using the PMP algorithm, forming the optimal initial co-state map. Thirdly, an adaptive co-state function consisting of fixed and dynamic terms was designed. The co-state map was interpolated using the initial SOC data and the vehicle driving data obtained by an Intelligent Transport System, and thereby the initial co-state values were solved and used as the fixed term. A segmented SOC reference curve was put forward according to the optimal SOC changing curves under different initial SOCs solved by using PMP. The dynamic term was determined using a PI controlling method and by real-time adjusting the co-states to follow the reference curve. Finally with the generated TDCs, the control effect of A-ECMS was compared with PMP and Constant-ECMS, which was showed A-ECMS provided the final SOC closer to the pre-set value and fully used the power of the batteries. The oil consumption solutions were close to the PMP optimized results and thereby the oil depletion was reduced.

Analysis of the Electric Bus Autonomy Depending on the Atmospheric Conditions

“…LTO batteries have the following advantages: operating safety, longevity, performance, and power density, but have a low energy density and are expensive [36]. The virtual model for the basic cell of the battery pack is shown in Figure 3, and, based on this model, the electrical equations that describe the characteristics of cells, modules, and of the battery packs were formulated [34,[37][38][39][40][41][42]. The voltage at the terminals of a cell (Ucell) is calculated with the following equation [38]: The virtual model for the basic cell of the battery pack is shown in Figure 3, and, based on this model, the electrical equations that describe the characteristics of cells, modules, and of the battery packs were formulated [34,[37][38][39][40][41][42].…”

Studies of Energy Consumption by a City Bus Powered by a Hybrid Energy Storage System in Variable Road Conditions

“…Initial research was related to the analysis of properties and the possibility of using mainly hybrid propulsion systems [6][7][8][9][10] in city buses using internal combustion engines in series [11] or parallel 2 of 39 layouts [12] as well as hydraulic drive [13] and CNG powered systems [14]. With the introduction of increasingly restrictive emissions standards for road transport, technological solutions based on purely battery drive systems [15] and their variants using hybrid battery-capacitors systems [16][17][18][19], replaceable energy store systems [20,21] or range extenders [22] are sought. In addition to the mentioned technologies, research related to the use of photovoltaic panels [23] or hydrogen fuel cells [24,25] for city electric buses was conducted.…”

Optimal Operating Point Determination Method Design for Range-Extended Electric Vehicles Based on Real Driving Tests

“…It is evident that increasing the battery capacity of EVs can increase their driving range; however, owing to issues related to battery weight and costs, it is not possible to indefinitely increase battery capacity in EVs [4][5][6][7][8]. Furthermore, in other efforts to extend the driving range of EVs, methods of maximizing their power conversion efficiency by reducing air and ground resistance as well as decreasing their weight have already been developed; it is noteworthy that these methods are not significantly different from those used in conventional vehicles using internal combustion engines.…”

“…In particular, Re-EVs consist of an engine and generator, i.e., a genset, which could provide extra electric power for charging the on-board battery, thus extending the traveling distance of the Re-EVs. [1,[4][5][6][7][12][13][14][15][16]. This increase of available energy can make Re-EVs suitable for use as various purpose-built vehicles, such as agricultural and industrial vehicles.…”

“…In rule-based energy management approaches, conventionally, the Re-EV is initially operated in a purely electric mode; however, when the SOC of the battery is below a certain threshold level, it is operated in the sustain mode. In contrast, some studies use optimization-based approaches to EV design, such as those involving equivalent consumption minimization strategy (ECMS), equivalent fuel consumption optimal control strategy (EFCOCS) [4][5][6], and dynamic programming (DP) methods [10,26].…”