A Review of Drive-Charging Integrated Systems and Control Strategies for Electric Vehicles

As a clean energy transportation, electric vehicles have attracted more and more attention due to their mature technology and low cost. However, the ability to charge the on-board power supply easily and efficiently has become a key factor limiting the industrialization of electric vehicles. Currently, AC slow-charging on-board charging system is considered as an effective solution to alleviate the charging problem of electric vehicles. The on-board charging system can make electric vehicles less dependent on charging posts and more convenient to charge. However, traditional drive and charging systems operate independently, which undoubtedly causes an increase in the size and weight of electric vehicles and limits the charging capacity. Therefore, the drive-charging integrated topology has been proposed to improve the utilization of on-board devices and effectively reduce costs. At present, the proposed drive-charging integrated systems vary in terms of their on-board charging system performance. Based on the existing studies, the drive-charging integrated topologies proposed in literatures have been sorted out, classified, and summarized according to different applications. It can be found that voltage matching, fast energy matching, electrical isolation, and rotor vibration noise in charging mode are still the key technical issues that need to be solved. The control strategies used to optimize the system performance in different operation modes are reviewed. The research on drive-charging integrated systems is one of the main trends to increase the power density of electric vehicles. There are still many problems. As a major research hotspot in the future, the following aspects related to the drive-charging integrated system should be considered: (1) Minimizing the number of accessory components and simplifying the topology are essential for achieving portability and cost-effectiveness, thereby reducing manufacturing costs and enhancing system reliability by mitigating equipment failures and losses caused by switching devices. (2) To better deal with the problem of matching the voltage between the on-board battery and the DC bus, a two-stage topology needs to be constructed. Tapping into new motor structure designs with two independent windings will be a continuous development research direction. (3) In-depth studies are required to improve the system reliability in charging mode and to address issues of energy conversion efficiency and losses in the electrical isolation section. (4) The current flowing through the motor winding during the charging mode can produce electromagnetic torque. The motor winding multiplexed as a charging inductor using current equalization control and multiplexed as a resolver to reduce motor vibration noise will be a hot spot for future research. (5) For motoring and braking modes, the studies on real-time tracking of load energy, energy detection of energy storage elements, and dynamic energy distribution of hybrid power systems are conducted to improve energy utilization efficiency. In the charging and V2G modes, control optimization based on the charging and discharging efficiency of the hybrid power system and auxiliary power quality regulation of the grid are required. In addition, adopting a multi-objective optimal control strategy to achieve optimal energy utilization efficiency of the power system in a complete operating cycle will become a major focus in integrated system research. © 2023 Chinese Machine Press. All rights reserved.