The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

Although the concept of variable-speed drives, based on utilization of multiphase machines, dates back to the late 1960s, it was not until the mid- to late 1990s that multiphase drives became serious contenders for various applications. These include electric ship propulsion, locomotive traction, electric and hybrid electric vehicles, ldquomore-electricrdquo aircraft, and high-power industrial applications. As a consequence, there has been a substantial increase in the interest for such drive systems worldwide, resulting in a huge volume of work published during the last ten years. An attempt is made in this paper to provide a brief review of the current state of the art in the area. After addressing the reasons for potential use of multiphase rather than three-phase drives and the available approaches to multiphase machine designs, various control schemes are surveyed. This is followed by a discussion of the multiphase voltage source inverter control. Various possibilities for the use of additional degrees of freedom that exist in multiphase machines are further elaborated. Finally, multiphase machine applications in electric energy generation are addressed.

Multiphase Electric Machines for Variable-Speed Applications

The area of multiphase variable-speed motor drives in general and multiphase induction motor drives in particular has experienced a substantial growth since the beginning of this century. Research has been conducted worldwide and numerous interesting developments have been reported in the literature. An attempt is made to provide a detailed overview of the current state-of-the-art in this area. The elaborated aspects include advantages of multiphase induction machines, modelling of multiphase induction machines, basic vector control and direct torque control schemes and PWM control of multiphase voltage source inverters. The authors also provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as an overview of the approaches to the design of fault tolerant strategies for post-fault drive operation, and a discussion of multiphase multi-motor drives with single inverter supply. Experimental results, collected from various multiphase induction motor drive laboratory rigs, are also included to facilitate the understanding of the drive operation.

/pdf/multiphase-induction-motor-drives-a-technology-status-review-1ir91893ja.pdf

Multiphase induction motor drives - : a technology status review

Fractional-slot concentrated-winding (FSCW) synchronous permanent magnet (PM) machines have been gaining interest over the last few years. This is mainly due to the several advantages that this type of windings provides. These include high-power density, high efficiency, short end turns, high slot fill factor particularly when coupled with segmented stator structures, low cogging torque, flux-weakening capability, and fault tolerance. This paper is going to provide a thorough analysis of FSCW synchronous PM machines in terms of opportunities and challenges. This paper will cover the theory and design of FSCW synchronous PM machines, achieving high-power density, flux-weakening capability, comparison of single- versus double-layer windings, fault-tolerance rotor losses, parasitic effects, comparison of interior versus surface PM machines, and various types of machines. This paper will also provide a summary of the commercial applications that involve FSCW synchronous PM machines.

Fractional-Slot Concentrated-Windings Synchronous Permanent Magnet Machines: Opportunities and Challenges

In this paper, a new battery/ultracapacitor hybrid energy storage system (HESS) is proposed for electric drive vehicles including electric, hybrid electric, and plug-in hybrid electric vehicles. Compared to the conventional HESS design, which uses a larger dc/dc converter to interface between the ultracapacitor and the battery/dc link to satisfy the real-time peak power demands, the proposed design uses a much smaller dc/dc converter working as a controlled energy pump to maintain the voltage of the ultracapacitor at a value higher than the battery voltage for the most city driving conditions. The battery will only provide power directly when the ultracapacitor voltage drops below the battery voltage. Therefore, a relatively constant load profile is created for the battery. In addition, the battery is not used to directly harvest energy from the regenerative braking; thus, the battery is isolated from frequent charges, which will increase the life of the battery. Simulation and experimental results are presented to verify the proposed system.

A New Battery/UltraCapacitor Hybrid Energy Storage System for Electric, Hybrid, and Plug-In Hybrid Electric Vehicles

With the advent of more stringent regulations related to emissions, fuel economy, and global warming, as well as energy resource constraints, electric, hybrid, and fuel-cell vehicles have attracted increasing attention from vehicle constructors, governments, and consumers. Research and development efforts have focused on developing advanced powertrains and efficient energy systems. This paper reviews the state of the art for electric, hybrid, and fuel-cell vehicles, with a focus on architectures and modeling for energy management. Although classic modeling approaches have often been used, new systemic approaches that allow better understanding of the interaction between the numerous subsystems have recently been introduced.

https://www.eee.hku.hk/doc/ccchan/Electric,%20Hybrid,%20and%20Fuel-Cell%20Vehicles-%20Architectures%20and%20Modeling.pdf

Electric, Hybrid, and Fuel-Cell Vehicles: Architectures and Modeling

Comparison of energy management strategies of a battery/supercapacitors system for electric vehicle under real-time constraints

In this paper, a new energy storage system (ESS) is developed for an innovative subway without supply rail between two stations. The ESS is composed of a supercapacitor bank and a braking resistor. An inversion-based control of the ESS is deduced from the Energetic Macroscopic Representation of the entire system. This control scheme requires a distribution criterion in order to allow the energy to be shared between the supercapacitors and the braking resistor. Different cases are evaluated via a Hardware-In-the-Loop simulation using a reduced-power ESS. The suggested control enables the energy recovery to be maximal and secure the supercapacitor in real time for different track configurations.

Energy Storage System With Supercapacitor for an Innovative Subway

Hardware-in-the-loop (HIL) simulations are more and more used to assess performances of electric drives. Software simulations lead to develop control of the studied system. In this case generally a lot of simplifications are assumed to reduce the computation time. Before a real-time implementation of the control, HIL simulations could be a very useful intermediary step. Thus a hardware device is introduced in the loop in order to take its real constraints into account. In this paper, three different kinds of HIL simulation are suggested: signal level, power level, and mechanical level. A example is given for the traction system of an electric scooter.

Different types of Hardware-In-the-Loop simulation for electric drives

The storage system in this paper is made of supercapacitors. The main goal is to ensure an efficient energy management in a series hybrid vehicle, even if braking resistors are still needed. Design considerations are discussed. In particular the influence of the inductor resistance on the system stability is described. A maximum control structure is then deduced from the energetic macroscopic representation of the storage system. Comparisons between experimentation and simulation are presented in order to highlight the influence of the inductor resistor. Experiments are then carried out on a normal operating cycle.

Alain Bouscayrol

Papers

Electric, Hybrid, and Fuel-Cell Vehicles: Architectures and Modeling

Comparison of energy management strategies of a battery/supercapacitors system for electric vehicle under real-time constraints

Energy Storage System With Supercapacitor for an Innovative Subway

Different types of Hardware-In-the-Loop simulation for electric drives

Design and Control of a supercapacitor storage system for traction applications