Hybrid Energy Storage System based on Modular Multilevel Series Parallel Converter

Hybrid energy storage system (HESS) having sources with complimentary characteristics is preferred in electric vehicle application, so as to fulfill the requirements such as reduced weight, long life of sources and improved dynamic response. In this paper, electric vehicle (EV) power conversion system is implemented with HESS which is comprised of battery and ultracapacitor (UC). UC has high power density and more life cycles compared to battery and battery has high energy density. Here UC delivers high current during acceleration and it can take in large and sudden current during regeneration and hence it improves the battery life. Bidirectional converter is used to drive the inverter driven induction motor (IM). Sources are charged during regenerative braking and hence it increases the efficiency of EV. An experimental prototype of EV power conditioner is developed and tested.

Supercapacitors, often referred to as Ultracapacitors, are electrochemical energy storage devices with high power density and moderate energy storage which serves as a bridge between the conventional capacitors and batteries. While conventional capacitors offer extreme power but negligible energy and batteries provide high energy density for long-term storage, Supercapacitors fill the gap between these technologies. By combining the rapid charge-discharge characteristics of conventional capacitors with comparatively enhanced energy storage capability associated with electrochemical systems, supercapacitors become highly suitable for applications that require substantial power delivery over short time interval. These distinct abilities of supercapacitors offer exceptional cycle stability, operational reliability and long service durability. The review focuses on the use of supercapacitors in power density and long cycle life applications, such as quick acceleration and regenerative braking in HEVs, power management in HESS, and battery-less electric vehicle technology based on supercapacitors with ultra-fast charging capabilities. In this paper, a comprehensive review of supercapacitor technology is presented, including the working principle, classification, materials, characteristics, and latest developments in supercapacitor technology. Moreover, the review critically discusses the applications of supercapacitors, such as RBS and HESS, along with the current challenges, limitations, and future research avenues for the betterment of supercapacitor technology. Keywords— Supercapacitors; High Power Density; Hybrid Energy Storage System (HESS); Regenerative Braking System (RBS); Electric Vehicles; Energy Management

To improve the performance and economy of the hybrid energy storage system (HESS) coordinating thermal generators to participate in automatic generation control (AGC), a HESS bi-layer capacity configuration model that considers the control strategy and net benefits of HESS is proposed. In addition, an improved mode-pursuing sampling (MPS) optimization algorithm based on meta-model is presented to improve the accuracy of model solving. In the lower layer, to improve the performance of HESS participating in AGC, a model predictive control (MPC) strategy is presented to distribute HESS power reasonably. Based on this, the upper layer develops a life-cycle net benefit model of HESS participating in AGC to improve its economy. The bi-layer model realizes iterative optimization of HESS capacity and operation through parameter transmission. Furthermore, to improve the solution accuracy of the bi-layer model, the convergence speed of the MPS algorithm is improved, so that the global search and local convergence speed can be taken into account. The case study results show that the bi-layer model can comprehensively consider the interaction between the economy and operating strategy of HESS. The proposed MPC strategy has better frequency regulation performance and the improved MPS algorithm has better solution performance.

This work presents a battery-ultracapacitor hybrid energy storage system (HESS) for pulsed loads (PL) in which ultracapacitors (UCs) run the pulse portion of the load while the battery powers the constant part of the load. Energy stored in UC depends upon the square of its voltage that’s why an active parallel hybrid topology with two bidirectional converters (BDC) is employed here that assigns UC a separate BDC to control its voltage between an upper and lower limit as per-requisite. The other converter is connected between the battery and DC-link to provide a distinct control of the battery. A MATLAB/Simulink model is developed to minimize the factors affecting the battery life such as capacity rate (C-rate), depth of discharge (DoD), and temperature rise due to PL by controlling the operating modes of the BDCs in which voltage of the UC and state of charge (SoC) of the battery are control variables. A constant output voltage across the load is maintained through feedback control. A detailed comparative analysis, among battery-alone, UC-alone, and battery-UC hybrid modes is performed which signifies that the proposed system is 55% lower in cost than its counterparts. The analysis shows that the proposed HESS reduces 50% capacity of a lead-acid battery, which is otherwise necessary to withstand the pulsating loads. Moreover, the performance of the HESS is also tested for electric vehicle (EV) load by hybridizing a high-voltage lithium-ion battery pack with a UC bank which confirms its suitability for EV applications.

To solve the problem of battery capacity degradation caused by high current magnitudes and frequent current variations in electric vehicles (EVs), a hybrid energy storage system (HESS) incorporating high energy density storage (battery) and high power density storage (ultracapacitor) is proposed. The HESS contains a multi‐port DC‐DC converter, which controls the energy flow among the battery pack, the ultracapacitor (UC) pack, and the port of output. Considering the state of charge (SOC) of UC, the speed, and demand power of EV, an energy management strategy (EMS) based on fuzzy logic control (FLC) for the HESS is proposed in this paper. According to the strategy, the battery pack serves as a base power source while the UC pack serves as a transient power source so as to smooth the battery pack current and prolong the battery life. Simulation and experiment results illustrate the effectiveness of the proposed strategy for UC/battery HESS in EVs. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

To solve the low power density issue of hybrid electric vehicular batteries, a combination of batteries and ultra-capacitors (UCs) could be a solution. The high power density feature of UCs can improve the performance of battery/UC hybrid energy storage systems (HESSs). This paper presents a parallel hybrid electric vehicle (HEV) equipped with an internal combustion engine and an HESS. An advanced energy management strategy (EMS), mainly based on fuzzy logic, is proposed to improve the fuel economy of the HEV and the endurance of the HESS. The EMS is capable of determining the ideal distribution of output power among the internal combustion engine, battery, and UC according to the propelling power or regenerative braking power of the vehicle. To validate the effectiveness of the EMS, numerical simulation and experimental validations are carried out. The results indicate that EMS can effectively control the power sources to work within their respective efficient areas. The battery load can be mitigated and prolonged battery life can be expected. The electrical energy consumption in the HESS is reduced by 3.91% compared with that in the battery only system. Fuel consumption of the HEV is reduced by 24.3% compared with that of the same class conventional vehicles under Economic Commission of Europe driving cycle.

In this paper, we develop formulation of a multi-objective optimization problem (MOOP) to optimally size a battery unit (BU) ultracapacitor (UC) hybrid energy storage system (HESS) for plug-in electric vehicle (EV). In this application, the objectives were to minimize cost, weight, volume of the HESS simultaneously maximizing the remaining cycle life of the BU at the end of the driving cycle. The MOOP is solved by the non-dominated sorting genetic algorithm type 2 algorithm. Detailed mathematical models for the BU and UC are given. The thermal effect on performance and sizing are also included in the formulation. The power demand by the EV powertrain is shared amongst the BU and HESS by two methods: First is by using wavelet transformation, while the second is by using power split ratio. The ratio of the power (i.e., power split) handled by each storage unit was determined by the optimizer. A sensitivity analysis was conducted for the power splitting ratio verification. The problem was solved for using the urban dynamometer driving schedule and the highway fuel economy test driving profiles. This has resulted in sizing of an HESS with lower cost, volume, and weight than those existing in literature. Finally, the effect of changing the motor type on the MOOP result was investigated.

In this paper we develop formulation of a multiobjective optimization problem (MOOP) to optimally size a battery unit (BU)-ultracapacitor (UC) hybrid energy storage system (HESS) for plug-in electric vehicle (EV). In this application, the objectives were to minimize cost, weight, volume of the HESS and simultaneously maximize the remaining cycle life of the BU at the end of the driving cycle. The MOOP solved by the Non-dominated Sorting Genetic Algorithm type 2 (NSGA-II) algorithm. Detailed mathematical models for the BU and UC are given. The thermal effect on performance and sizing are also included in the formulation. The power demand by the EV powertrain is shared among the BU and HESS by two methods: the first is by using wavelet transformation, while the second is by using power split ratio. The ratio of the power (i.e: power split) handled by each storage unit was determined by the optimizer. A sensitivity analysis was conducted for the power splitting ratio verification. The problem was solved for the Urban Dynamometer Driving Schedule (UDDS) driving profile. The results of the HESS size were used in the Highway Fuel Economy Test (HFET) driving schedule analysis. This has resulted in sizing of a HESS with lower cost, volume and weight than those existing in literature.

The main purpose of this paper is to describe a novel power management control strategy for battery and supercapacitor hybrid energy storage system with the objective that the load power demand would be distributed into the energy storage devices in a way that each device can be utilized optimally. The paper describes the design and control of such an on-board hybrid energy storage system. The specific control strategy is designed based on a fuzzy-logic controller (FLC), which offers the advantage of flexibility and robustness and has been widely applied to the energy management or power distribution of multiple power sources system of an electric vehicle, to avoid the low efficiency operation region of every power source and achieve high efficiency without degrading the mechanism performance. However, prior experience fuzzy logic supervisory control is often difficulty in realizing the optimal distribution between battery and supercapacitor. In the presented research, an optimization method based on gold ratio cut-off rule is proposed to design the degree of hybridization (DOH) and membership functions of the fuzzy controller, to realize the optimal performance of fuzzy logic controller. The proposed optimization method is simple and effective, and can be applied to the practical hybrid system directly. Finally, the effectiveness of the proposed method was examined by using ADVISOR simulation platform, and in which the hybrid energy storage system was developed and embedded into the electric vehicle model. The model parameters were gained from the tested vehicle. Simulation results have shown that the proposed method can efficiently distribute the power between battery and supercapacitor to realize the design objective set forth.

The power management capabilities of hybrid energy storage systems offer several advantages for EVs, including improved performance, longer battery life, and reduced cost. HES technologies which combine Li-ion cells with ultra-capacitors (UC), are developing as just a possible alternative to the constraints of conventional ESS for conserving electricity. Lithium-ion batteries have a limited cycle life, meaning that they gradually degrade with each charge-discharge cycle. This can reduce the overall lifetime of the ESS and require more frequent replacements, adding to the cost and environmental impact of EVs. To circumvent those constraints, mixed battery packs combining battery technology as well as superconductors are being developed. To improve the design and control of hybrid energy storage systems for electric vehicles (EVs), a bi-level multi-objective framework has been proposed. A Bi-level multi-objective design and control framework, incorporating NSGA-II and fuzzy logic control, to obtain an optimal sized hybrid energy storage system and corresponding power management strategy. This dynamic and multi-objective architecture may achieve optimum solution hybrids battery bank as well as a matching significant power scheme one at a moment through integrating non-dominated sorting genetic and fuzzy logic control methods. To evaluate the effectiveness of the proposed bi-level multi-objective framework, Pareto optimal solutions of different hybrid energy storage systems are obtained. This approach can lead to significant improvements in the performance and efficiency of hybrid energy storage systems, making them more suitable for EVs and other applications that require high-performance energy storage solutions. Index Terms—Batteries, ultra capacitors, recursive imprecise input, non – linear and non optimisation, and e – mobility

Coordinated Active Power Control of Hybrid Energy Storage System for AC Micro-Grids in Islanding Mode

A Hybrid Energy Storage System (HESS), consists of two or more types of energy storage technologies, mostly includingbatteries, flywheels, super-capacitors, and fuel cells. The complementary features of HESS make it outperform any single energy storage device depending on the application energy requirements in different scenarios/conditions. To overcome the opposing limitations of battery and supercapacitor, the battery has relatively high energy density but low power density as compared to the supercapacitor, an active battery/supercapacitor hybrid energy storage system (HESS) with dc/dc converter is proposed. However, the main issue with an active battery/supercapacitor HESS is current flow control to accomplish two goals: minimizing the magnitude fluctuation of current flowing in/out of the battery and minimizing energy loss experienced by the supercapacitor/s. The purpose of this article is to perform optimization of an active battery/supercapacitor HESS for a Hybrid Electric Vehicle (HEV). The HESS topology used for the optimization consists of a parallel connected battery and supercapacitor/s to drive the load through the respective dc/dc converters. In this article, an efficient multiplicative-increase-additive-decrease concept-based algorithm is used to ensure an optimal solution. MATLAB simulations are used to demonstrate that the proposed scheme can optimally minimize the magnitude fluctuation of the battery current and the SC energy loss.

Electric Vehicles (EVs) are the best alternative to deal with fossil fuel and air pollution crisis. These vehicles have an electrical propulsion system which is connected to an Energy Storage System (ESS). Internal combustion engine propulsion system (parallel hybrid EV), engine-generator (series hybrid EV), or fuel cell system (fuel cell hybrid EV) may also exist in an EV. High performance ESS is needed as a result of electric power requirement. The batteries, conventional ESS, have high energy and low power specifications for use in EVs. Another candidate for EV's ESS is ultra-capacitor (UC). The ultra-capacitors have very low energy and high power specifications. In recent years, some designs have been proposed to combine batteries and ultra-capacitors to develop a hybrid energy storage system (HESS) with high energy and high power specifications. In this kind of ESS, the power fluctuation of the battery is reduced and the life of the battery is increased. In this study, the behavior of a heavy duty EV with an ESS is compared with a HESS one. This comparison is done in 5 different driving cycles which have different level of aggressiveness. The results show that the vehicle performance, the energy saving characteristics and the battery life criteria improvement values are related to the aggressiveness characteristics of driving cycles.

Only battery-powered electric/hybrid electric vehicles have been suffering from driving range as well as peak power generation; in order to overcome those problems the size of the battery may be increased. But this solution again remains with some drawback like increased size, weight and cost of the vehicle. Hybrid Energy Storage System (HESS) has been developed by mixing battery with Ultracapacitor (UC). UC always supplies the peak power and battery is mending to supply the average power. In order to obtain the proper switching between the battery and UC, a new controller has been designed based on the speed of an electric motor. Four individual math functions are taken and programmed based on the speed of an electric motor for successful four modes of operation termed as Math Function Based (MFB) controller. The designed MFB controller has been implemented in all modes of electric motor operation in MATLAB/Simulation and results are plotted and discussed in Simulation and results section.

The DC-DC converter crucial in modern power electronic systems. They are extensively used in renewable energy integration, hybrid electric vehicles (HEVs) and portable electronic devices. For the electric vehicles (EVs) with a hybrid energy storage system (HESS) that includes both battery and ultracapacitor (UC) efficient power management is the key feature for improving system performance, reliability, and the lifespan of the storage units. This paper mainly focusses on improving how energy is managed in electric vehicles (EVs) by the help of hybrid energy storage system (HESS) that includes-ultra capacitor, solar photovoltaic (PV) and battery input. Hear to control the flow of power which from the sources to EV load, I design a versatile non isolated multiport converter for integration of solar PV, battery and ultracapacitor and getting a single output. This paper suggests a non-isolated multi-input, single-output multiport converter design. This architecture aims to offer flexibility in the power flow while adjusting to the changing load demands of EVs. The DC-DC converter manages varying power demands by selecting the most appropriate energy source and channeling power through the proper paths depending on whether high or low current are required. It also supports bidirectional power transfer, enabling sources in both directions. Moreover, the converter allows single- stage power conversion, thereby improving the overall efficiency of the system.