Smart Integration of Electric Buses in Cities: A Technological Review

Abstract

This paper provides a comprehensive overview of the state-of-the-art related to the implementation of battery electric buses (BEBs) in cities. In recent years, bus operators have started focusing on the electrification of their fleet to reduce the air pollutants in cities, which has led to a growing interest from the scientific community. This paper presents an analysis of the BEB powertrain topology and the charging technology of BEBs, with a particular emphasis on the power electronics systems. Moreover, the different key technical requirements to facilitate the operation of BEBs are addressed. Accordingly, an in-depth review on vehicle scheduling, charger location optimization and charging management strategies is carried out. The main findings concerning these research fields are summarized and discussed. Furthermore, potential challenges and required further developments are determined. Based on this analysis, it can be concluded that an accurate energy consumption assessment of their BEBs is a must for bus operators, that real-time, multi-objective smart charging management strategies with V2X features should be included when performing large bus fleet scheduling and that synchronized opportunity charging, smart green depot charging, and electric bus rapid transit can further reduce the impact on the grid. This review paper should help to enable a smarter and more efficient integration of BEBs in cities in the future.

Direct Predictive Power Control Strategy to Improve Charging and Power Quality of Autonomous Robotic Electric Vehicle Charging Systems

“…This technique has advantages over standard PI based control strategy. As reported in [18], THD of line current is 3.5% and 2.8% for G2V and V2G, respectively. MPC does not require any additional voltage-current loops, modulators or PLLs.…”

“…( 1)-( 8) have been derived in a 𝛼𝛽 reference frame for the three-phase AFE AC-DC bidirectional converter, based on Fig 2 [21]. These first-order differential equations of the LCL filter are utilized to create the state-space model [18] [22]. The discrete state-space model is further utilized to implement the MPC algorithm.…”

“…These improvements are necessary for the next-generation off-board chargers. However, since WBG semiconductors are only used in a limited number of applications today, there is a strong need for accurate models of such systems and new controllers to cope with the high switching frequencies and the fast dynamics of these devices [9].…”

Real-Time Charging Scheduling and Optimization of Electric Buses in a Depot

“…As a result, public transport operators (PTOs) of European cities are looking at battery electric buses (BEBs) to replace their current diesel fleet [2]. This transition however presents several challenges which must be overcome, such as the rescheduling of the vehicle operations due to the limited range of BEBs, reducing the total cost of ownership (TCO) and improving the power quality [3].…”

Design and Real-Time Implementation of a Control System for SiC Off-Board Chargers of Battery Electric Buses

“…Indeed, there is a lack of accurate models of such systems and new controllers to cope with the devices' high switching frequencies and fast dynamics. Moreover, the commercially available off-board chargers for BEBs mostly have an efficiency >95% [8]. This research aims to design a charger for the specification of BEBs to enhance efficiency >97% and reduce size and weight through the integration of WBG semiconductors.…”