Battery electric vehicles ( BEVs ) are the most interesting option available for reducing CO 2 emissions for individual mobility. To achieve better acceptance, BEVs require a high cruising range and good acceleration and recuperation. To meet these requirements, hybrid energy storage systems can be used, which combine high-power ( HP ) and high-energy ( HE ) storage units. To date, the coupling of the two energy storage types has been realized passively or actively by using DC/DC converters. In this paper, the corresponding topologies, described in the literature, are presented and reviewed with focus on the usable voltage window of the energy storage types, the utilization of stored energy, the connection to a power train/load, and additionally required power electronics. Besides, reconfigurable topologies on cell level and module level, without the need of additional DC/DC converters, have been investigated in the literature and are also presented and reviewed. We then suggest a new topology class of discrete hybrid energy storage topologies , which combine both research topics. In the proposed topology class, standardized energy storage modules ( ESMs ) consisting of either HP or HE devices are combined. Each ESM is equipped with switching elements, which can activate, bypass, or disable the module and therefore allow reconfigurations. Four sub-topologies emerge when these ESMs are arranged to form an energy storage system.

Review of system topologies for hybrid electrical energy storage systems

The studies for hybrid electrical vehicle (HEV) have attracted considerable attention because of the necessity of developing alternative methods to generate energy for vehicles due to limited fuel based energy, global warming and exhaust emission limits in the last century. HEV incorporates internal composition engine, electric machines and power electronic equipment. In this paper, an overview of HEVs is presented. In fact, we aim to introduce the HEVs and present their history, advantages, disadvantages, classification, vehicle types, energy management strategies and some other related information. The methodology used in this paper is descriptive, library and analytical. The descriptive aspect of this paper is based on identification and definitions and its required materials and information have been complied using related scientific papers.

Hybrid electric vehicles: An overview

Vehicle models whose propulsion system is based on electric motors are increasing in number within the automobile industry. They will soon become a reliable alternative to vehicles with conventional propulsion systems. The main advantages of this type of vehicles are the non-emission of polluting gases and noise and the effectiveness of electric motors compared to combustion engines. Some of the disadvantages that electric vehicle manufacturers still have to solve are their low autonomy due to inefficient energy storage systems, vehicle cost, which is still too high, and reducing the recharging time. Current regenerative systems in motorcycles are designed with a low fixed maximum regeneration rate in order not to cause the rear wheel to slip when braking with the regenerative brake no matter what the road condition is. These types of systems do not make use of all the available regeneration power, since more importance is placed on safety when braking. An optimized regenerative braking strategy for two-wheeled vehicles is described is this work. This system is designed to recover the maximum energy in braking processes while maintaining the vehicle’s stability. In order to develop the previously described regenerative control, tyre forces, vehicle speed and road adhesion are obtained by means of an estimation algorithm. A based-on-fuzzy-logic algorithm is programmed to carry out an optimized control with this information. This system recuperates maximum braking power without compromising the rear wheel slip and safety. Simulations show that the system optimizes energy regeneration on every surface compared to a constant regeneration strategy.

Regenerative Intelligent Brake Control for Electric Motorcycles

This paper proposes a low cost system that can add the ability of regenerative breaking to small electric vehicles. The system uses ultracapacitors to store the energy harvested during braking, and its capacity is kept as low as possible in order to reduce the overall cost of the system. It is also proposed a power electronic topology that can transfer energy from the ultracapacitors to the motor or to the main battery, from the battery to engine and from the engine to the main battery. It is further proposed a new method of control that makes driving more pleasant and reduces consumption by avoiding sudden accelerations.

Sergio Sousa

Papers

A new control method of an electric scooter with a hybrid ultracapacitor/battery energy storage topology