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Battery safety is one of the most crucial issues in the utilization of lithium-ion batteries (LiBs) for all-climate electric vehicles. Short circuit, overcharge, and overheat are three common field failures of LiBs. In this paper, online fault diagnosis for external short circuit (ESC) of LiB packs is investigated. The experiments are carried out to obtain and compare ESC characteristics of 18650-type NMC battery pack and single cell. Based on the analysis of experimental results, a two-step equivalent circuit model is established to describe the ESC process and an online model-based scheme is proposed to diagnose ESC faults of battery packs. The proposed scheme is evaluated by experimental data. The results show that it can effectively diagnose ESC faults in 3.5 s after their occurrences with the terminal voltage error less than 25 mV. The proposed scheme has shown great generalization ability. ESC faults of battery packs under different number of cells connected in series and unavailable current information can also be diagnosed at the terminal voltage error less than 48 and 60 mV, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a decoupled power control strategy for a modular multilevel converter (MMC)-based hybrid ac–dc grid integrated with a hybrid energy storage system. This system can mitigate the active power fluctuations caused by intermittent renewable generation and also realize reactive power compensation as required by voltage regulation. The proposed hybrid ac–dc system has a novel configuration in which batteries and supercapacitors are distributed into the upper arm and the lower arm of the MMC, respectively. Therefore, it is possible to design fully decoupled power control and simultaneously optimize the performances of batteries and supercapacitors. First, the system modeling and operational principles of the MMC are briefly introduced in this paper. On the basis of these analyses, the power decoupling between the upper arm and the lower arm is presented to realize different control objectives. Moreover, battery state-of-charge balancing control and supercapacitor voltage control are also presented, which are crucial for ensuring the normal operation of these energy storage components and the proposed MMC-based hybrid ac–dc grid. Finally, the proposed system and its control strategies are verified by laboratory experimental results. [ABSTRACT FROM AUTHOR]

This paper investigates the use of large-scale wayside energy storage to reduce operational costs of ac electric traction power networks. This paper also introduces a method of estimating the battery capacity, based on manufacturer's charging and discharging specifications. The battery model is simple and easy to incorporate into load flow simulation algorithms. The concept and the battery model are validated through a feasibility study within Aurizon's heavy haul electric railway network. [ABSTRACT FROM AUTHOR]

This paper presents a novel two-dimensional real-time modeling approach for a proton exchange membrane fuel cell (PEMFC) based on a tridiagonal matrix algorithm (Thomas algorithm). The Thomas algorithm consists of a forward elimination and a backward substitution, its arithmetic complexity of computations being much lower than the Gaussian elimination. In order to use this advanced numerical solver, the differential equations of reactant gas convection and diffusion phenomena in serpentine channels are transformed into a tridiagonal equations system. In addition, a three-level bisection algorithm has been developed to solve spatial physical quantities distribution for electrochemical domain. The real-time computing methods developed in this paper are then implemented in C language for a fast execution time in a real-time processor. The proposed real-time model is experimentally validated using a 1.2 kW Ballard NEXA fuel cell system, and its practical feasibilities in advanced real-time control for PEMFC systems have been experimentally demonstrated in an RT-LAB real-time simulator. [ABSTRACT FROM PUBLISHER]

This paper presents a hybrid battery parameterization technique for the purpose of battery state-of-charge (SOC) and state-of-power (SOP) monitoring in real time. The proposed technique is centered around an opportunistic initialization of a dual extended Kalman filter (DEKF) algorithm using pseudorandom binary sequence (PRBS) battery excitation. A second-order electrical equivalent-circuit battery model is used whose parameters are identified using a carefully designed 10-bit 10-Hz PRBS signal while the battery is in a zero- or low-current quiescent mode. The PRBS-identified resistive elements of the battery model are then utilized to provide an initial estimate for the battery's SOP. Once in load conditions, the DEKF algorithm is implemented recursively to provide an accurate estimate of the battery's parameters, SOC, and subsequently its SOP in real time. The experimental results obtained from an electrochemical impedance spectroscopy method give confidence to the performance of the proposed hybrid battery parameterization technique. [ABSTRACT FROM AUTHOR]

Accurate information of battery internal variables is crucial for health-conscious and optimal battery management. Due to lack of measurements, advanced battery management systems rely heavily on estimation algorithms that provide such internal information. Although algorithms for cell-level charge and health estimation have been widely explored in the literature, algorithms for electrode-level quantities are almost nonexistent. The main obstacle in electrode-level estimation is the observability problem where the individual electrode states are not observable from terminal voltage output. However, if available, real-time feedback of electrode-level charge and health can be highly beneficial in maximizing energy utilization and battery life. Motivated by this scenario, in this paper we propose a real-time algorithm that estimates the available charge and health of individual electrodes. We circumvent the aforementioned observability problem by proposing an uncertain model-based cascaded estimation framework. The design and analysis of the proposed scheme are aided by a combination of Lyapunov's stability theory, adaptive observer theory, and interconnected systems theory. Finally, we illustrate the effectiveness of the estimation scheme by performing extensive simulation and experimental studies. [ABSTRACT FROM AUTHOR]

An electrical variable transmission (EVT) is an electromagnetic power-split device with two mechanical and two electrical ports. It can be used in hybrid electric vehicles to split the power to the wheels in a part coming from the combustion engine and a part exchanged with the battery. Although crucial for the EVT design and evaluation, no papers are found to give a detailed overview of the different loss components in such a machine and how they can be calculated and measured. In contrast to conventional electrical machines, this machine has more degrees of freedom, which can be exploited to measure the different loss contributions separately. This paper proposes a methodology to identify and measure the different loss components in this kind of machines. The proposed method is able to identify the iron losses in stator and inner rotor, the copper losses, bearing losses, and slip ring friction losses separately. To this end, measurements of both torque and speed sensors in different operating points are combined. The methods are applied to identify the different loss contributions in a prototype permanent magnet assisted EVT, both in no-load operation as under load where its functionality as power-split device is evaluated. [ABSTRACT FROM PUBLISHER]

A new light emitting diode (LED) driver circuit is presented in this paper based on the buck converter with coupled inductors for automotive applications. Soft-switching condition is provided for the switch via a passive resonant circuit incorporating the leakage inductance of the coupled inductors. Also, the leakage inductance energy is recycled to the output. The proposed converter has a very simple structure as well as high efficiency, which makes it a good candidate for battery-operated applications. The proposed converter only applies one magnetic element and the leakage and magnetizing inductances are used as resonant elements. Also, during the resonance, a resonance capacitor is approximately charged to the input voltage, and therefore, the capacitor voltage stress and semiconductor devices voltage stress are low. These are the main advantages of the proposed converter over other similar converters. The theoretical analysis is provided and the operating principles and design considerations are explained. An 8 W laboratory prototype is implemented in order to prove the validity of the theoretical analysis. [ABSTRACT FROM AUTHOR]

In conventional hybrid energy storage systems, two storage units complement each other. One low-capacity and fast-response unit as a power supplier, and one high-capacity and low-response unit as an energy supplier. The power supplier mitigates fast fluctuations in generation or demand by transferring energy over seconds or minutes, and the energy supplier transfers energy over hours for managing energy. According to this concept, this paper presents a new model of hybrid energy storage systems, where three energy suppliers are considered as a three-level hybrid energy storage system. Energy storage at level 1 shifts energy from off-peak (or low-cost) hours to the on-peak (or high-cost) hours during one day, the storage unit at level 2 transfers energy from off-peak (or low-cost) days to the on-peak (or high-cost) days for the period of one week, and level 3 transfers energy from off-peak seasons to the on-peak seasons through one year. The proposed planning results in a large-scale optimization programming that optimizes large numbers of design variables at the same time. In order to increase the flexibility of the planning, the initial energy of the storage units is also modeled as a design variable and optimized. The uncertainty of loads is modeled and a stochastic planning is carried out to solve the problem. The introduced three-level hybrid energy storage planning is simulated on two test systems, and the results demonstrate that the proposed planning can reduce the planning cost by about 1.8%. [ABSTRACT FROM AUTHOR]

A novel three-level (3L) bidirectional converter (BDC) is proposed in this paper. Compared with the traditional BDC, the inductor of the 3L BDC can be reduced significantly so that the dynamic response is greatly improved. Hence, the proposed converter is very suitable for fuel-cell/battery hybrid power systems. In addition, the voltage stress on the switch of the proposed converter is only half of the voltage on the high-voltage side, so it is also suitable for high-voltage applications. The operation principle and the implementation of the control circuit are presented in detail. This paper also proposes a novel bidirectional soft-start control strategy for the BDC. A 1-kW prototype converter is built to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

Wireless power transfer system (WPTS)-based wireless electric vehicles, classified into roadway-powered electric vehicles (RPEVs) and stationary charging electric vehicles (SCEVs), are in the spotlight as future mainstream transportations. RPEVs are free from serious battery problems such as large, heavy, and expensive battery packs and long charging time because they get power directly from the road while moving. The power transfer capacity, efficiency, lateral tolerance, electromagnetic field, air-gap, size, weight, and cost of the WPTSs have been improved by virtues of innovative semiconductor switches, better coil designs, roadway construction techniques, and higher operating frequency. Recent advances in WPTSs for RPEVs are summarized in this review paper. The fifth- and sixth-generation online electric vehicles, which reduce infrastructure cost for commercialization, and the interoperability between RPEVs and SCEVs are addressed in detail in this paper. Major milestones of the developments of other RPEVs are also summarized. The rest of this paper deals with a few important technical issues such as coil structures, power supply schemes, and segmentation switching techniques of a lumped inductive power transfer system for RPEVs. [ABSTRACT FROM PUBLISHER]

There is an emerging application, which uses a mixture of batteries within an energy storage system. These hybrid battery solutions may contain different battery types. A dc-side cascaded boost converters along with a module-based distributed power sharing strategy has been proposed to cope with variations in battery parameters such as, state-of-charge (SOC) and/or capacity. This power sharing strategy distributes the total power among the different battery modules according to these battery parameters. Each module controller consists of an outer voltage-loop with an inner current-loop where the desired control reference for each control-loop needs to be dynamically varied according to battery parameters to undertake this sharing. As a result, the designed control bandwidth (BW) or stability margin of each module control-loop may vary in a wide range, which can cause a stability problem within the cascaded converter. This paper reports such a unique issue and thoroughly investigates the stability of the modular converter under the distributed sharing scheme. The paper shows that a cascaded PI control-loop approach cannot guarantee the system stability throughout the operating conditions. A detailed analysis of the stability issue and the limitations of the conventional approach are highlighted. Finally in-depth experimental results are presented to prove the stability issue using a modular hybrid battery energy storage system prototype under various operating conditions. [ABSTRACT FROM AUTHOR]

In this paper, a novel mixed iterative adaptive dynamic programming (ADP) algorithm is developed to solve the optimal battery energy management and control problem in smart residential microgrid systems. Based on the data of the load and electricity rate, two iterations are constructed, which are $P$ -iteration and $V$ -iteration, respectively. The $V$-iteration is implemented based on value iteration, which aims to obtain the iterative control law sequence in each period. The $P$-iteration is implemented based on policy iteration, which updates the iterative value function according to the iterative control law sequence. Properties of the developed mixed iterative ADP algorithm are analyzed. It is shown that the iterative value function is monotonically nonincreasing and converges to the solution of the Bellman equation. In each iteration, it is proven that the performance index function is finite under the iterative control law sequence. Finally, numerical results and comparisons are given to illustrate the performance of the developed algorithm. [ABSTRACT FROM PUBLISHER]

Smart energy management system (SEMS) is a core part of a smart grid system, which can make this system more intelligent. The final goal of SEMS is to lay a groundwork which would allow efficient management of the smart grid by minimizing the operating costs and by reducing the emission level while meeting the load demand. In this paper, a new technique called as the jump and shift method is developed to handle the multi-objective optimization in SEMS. A 14-bus microgrid (MG) and a 112-bus power system are used to verify the multi-objective optimization algorithm based on the jump and shift method. The results show that the proposed technique performs very well, and it can be used to solve the multi-objective optimization in SEMS for smart grids. [ABSTRACT FROM AUTHOR]

This paper describes the configuration, modeling, and control of a fuel cell (FC)-battery-powered hybrid system for the Metro Centro tramway in Seville, Spain. The proposed hybrid system presents a polymer electrolyte membrane FC as the primary energy source and a nickel-metal hydride cell battery as the secondary energy source, which supplements the output of the FC during tramway acceleration or whenever else needed and cruise and for energy recovery during braking. The tramway presents a traction system which is composed of four traction induction motor drives. The hybrid system also supplies the power for the auxiliary services. The power conditioning system is composed of two converters: 1) a boost-type unidirectional dc/dc converter for the FC and 2) a boost-type bidirectional dc/dc converter for the battery. The energy management system (EMS) of the hybrid tramway determines the reference signals for the electric motor drives, FC, and power converters in order to regulate accurately the power from the two electrical sources. EMS also determines the reference signal for energy dissipation in braking chopper when required during regenerative braking. In this paper, the proposed hybrid system is evaluated for the real driving cycle of the tramway. The results demonstrate the hybrid system capability to meet appropriate driving cycle. [ABSTRACT FROM PUBLISHER]

This paper proposes a new soft-switching bidirectional dc/dc converter. The proposed converter achieves zero-voltage switching (ZVS) for the entire main switches and zero-current switching for the rectifier diodes in the large-load range. These features reduce switching loss, voltage and current stresses, and diode reverse-recovery effect. The simple electrical isolated topology with the soft-switching characteristic provides an attractive solution for a battery charge/discharge system in an electric vehicle, distributed power system, or uninterruptible power system. This paper describes the operation principle and the ZVS condition in detail. The mathematical model based on the state-space averaging method is also deduced to depict the performance characteristic. Then, design guidelines are presented to ensure the ZVS condition for all the switches. Finally, simulation and experimental results obtained from a 1-kW prototype verify the discussed theoretical analysis. [ABSTRACT FROM AUTHOR]

Among the various kinds of electrical vehicle (EV) prototypes presented by the car manufacturers, fuel-cell EVs seem to be a very promising solution. Five different fuel-cell technologies are available in the research laboratories. Nevertheless, only two technologies can really be considered for transportation applications due to their solid electrolyte, i.e., proton exchange membrane fuel cells (PEMFCs) and solid oxide fuel cells. The PEMFCs are investigated in this paper. When talking about EV design, a simulation model of the whole fuel-cell system is a binding milestone. This would lead in the optimization ability of the complete vehicle (including all ancillaries, output electrical converter, and their dedicated control laws). Nevertheless, the fuel-cell model is strongly dependent on many physicochemical parameters that are difficult to evaluate on a real PEMFC stack. Moreover, the analytical relations governing the behavior of a PEMFC system are also far from being easy. Thus, a "minimal behavioral model" of a fuel-cell system, which is able to evaluate the output variables and their variations, is highly interesting. Artificial neural networks propose a very efficient tool to reach such an aim. In this paper, a PEMFC neural network model is proposed. [ABSTRACT FROM AUTHOR]

In this paper, a resonant current-mode receiver is studied to charge low-voltage batteries wirelessly for supplying medical implantable systems. To increase efficiency, the root-mean-square (rms) current in the LC tank of the receiver (RX) is reduced by using a voltage-boosted current-mode (VBCM) receiver. This receiver combines the conventional current-mode receiver with a switched-capacitor converter to boost the voltage instantaneously at the switching node ($V_{X}$) of coil. Owing to the suggested technique, the receiver directly charges a low-voltage battery while maintaining a small rms current without using a complex voltage regulator. The receiver achieves an efficiency as high as 84.7% with a 1.1 V battery while operating at the resonant frequency ($f_{{\text{reso}}}$) of 6.78 MHz. The power delivered to the output ($P_{O}$) is in the range from 1.5 to 50 mW. The VBCM receiver was fabricated by 180 nm CMOS technology with a total active area of 0.22 mm2. [ABSTRACT FROM AUTHOR]

A compact digitally controlled fuel cell/battery hybrid power source is presented in this paper. The hybrid power source composed of fuel cells and batteries provides a much higher peak power than each component alone while preserving high energy density, which is important and desirable for many modern electronic devices, through an appropriately controlled dc/dc power converter that handles the power flow shared by the fuel cell and the battery. Rather than being controlled to serve only as a voltage or current regulator, the power converter is regulated to balance the power flow to satisfy the load requirements while ensuring the various limitations of electrochemical components such as battery overcharge, fuel cell current limit (FCCL), etc. Digital technology is applied in the control of power electronics due to many advantages over analog technology such as programmability, less susceptibility to environmental variations, and low parts count. The user can set the FCCL, battery current limit, and battery `voltage limit in the digital controller. A control algorithm that is suitable for regulating the multiple variables in the hybrid system is described by using a state-machine-based model; the issues about embedded control implementation are addressed; and the large-signal behavior of the hybrid system is analyzed on a voltage-current plane. The hybrid power source is then tested through simulation and validated on real hardware. This paper also discusses some important issues of the hybrid power source, such as operation under complex load profiles, power enhancement, and optimization of the hybrid system. The design presented here can not only be scaled to larger or smaller power capacities for a variety of applications but also be used for many other hybrid power sources. [ABSTRACT FROM AUTHOR]

Fuel cells probably represent the power-production technology receiving the most development attention. The objective of this paper is to regulate the output voltage of inverters for fuel-cell power plants. This lettter describes an effective fuzzy-logic (FL) flux control. The paper demonstrates that the proposed method provides an improved response compared to the conventional flux-control method. [ABSTRACT FROM AUTHOR]

Multilevel converters have received more attention recently. Multilevel converters can be used not only in high-voltage high-power applications, but also in energy storage systems, thanks to reduced harmonics and electromagnetic interferences. State-of-charge (SoC) balancing of the storage system cells within cascaded multilevel inverters, e.g., batteries, can be one of the challenges in practical applications. Different methods have been studied and reported in technical literature. However, the SoC balancing is still a challenging issue. In this paper, a new method is proposed to solve this problem by applying several clever but simple changes to the staircase modulation switching scheme without changing the output waveform properties. Validations for this simple method were performed through simulation and experimental prototype. Despite the simplicity of the method, the simulation and experimental results show that SoC balancing of the cells has significantly improved. [ABSTRACT FROM PUBLISHER]

High-boost dc-ac inverters are used in solar photovoltaic (PV), fuel cell, wind energy, and uninterruptible power supply systems. High step-up and step-down capabilities and shoot-through immunity are some of the desired properties of an inverter for a reliable, versatile, and low-distortion ac inversion. The recently developed Z-source inverter (ZSI) possesses these qualities. However, the realization of ZSI comes at a cost of higher passive component count as it needs two sets of passive filters. A switched boost inverter (SBI) has similar properties as ZSI, and it has one L\-C pair less compared to ZSI, but its gain is less than ZSI. This paper proposes the current-fed switched inverter (CFSI) which combines the high-gain property of ZSI and low passive component count of SBI. The proposed inverter uses only one L\-C filter and three switches apart from the inverter structure. The inverter topology is based on current-fed dc/dc topology. Steady-state analysis of the inverter is presented to establish the relation between the dc input and the ac output. A pulse width modulation (PWM) control strategy is devised for the proposed inverter. An experimental prototype is built to validate the proposed inverter circuit in both buck and boost modes of operation. A 353-V dc-link and a 127 V (rms) ac are obtained from a 35.3-V dc input to demonstrate the boost mode of operation. A 200-V dc-link and a 10.5-V (rms) ac are obtained from a 37.8-V dc input to verify the buck mode of operation of CFSI. [ABSTRACT FROM PUBLISHER]

This paper presents novel machine-learning-based methods for estimating the state of charge (SoC) of lithium-ion batteries, which use the Gaussian process regression (GPR) framework. The measured battery parameters, such as voltage, current, and temperature, are used as inputs for regular GPR, whereas the SoC estimate at the previous sample is fed back and incorporated into the input vector for recurrent GPR. The proposed methods consist of two parts. In the first part, training is performed wherein the optimal hyperparameters of a chosen kernel function are determined to model data properties. In the second part, online SoC estimation is carried out according to the trained model. One of the practical advantages of a GPR framework is to quantify estimation uncertainty and, hence, to enable reliability assessment of the battery SoC estimate. The performance of the proposed methods is evaluated by using a simulated dataset and two experimental datasets, one with constant and the other with dynamic charge and discharge currents. The simulations and experimental results show the superiority of the proposed methods in comparison to state-of-the-art techniques including a support vector machine, a relevance vector machine, and a neural network. [ABSTRACT FROM PUBLISHER]

The quasi-Z-source inverter (qZSI) with battery operation can balance the stochastic fluctuations of photovoltaic (PV) power injected to the grid/load, but its existing topology has a power limitation due to the wide range of discontinuous conduction mode during battery discharge. This paper proposes a new topology of the energy-stored qZSI to overcome this disadvantage. The operating characteristic of the proposed solution is analyzed in detail and compared to that of the existing topology. Two strategies are proposed with the related design principles to control the new energy-stored qZSI when applied to the PV power system. They can control the inverter output power, track the PV panel's maximum power point, and manage the battery power, simultaneously. The voltage boost and inversion, and energy storage are integrated in a single-stage inverter. An experimental prototype is built to test the proposed circuit and the two discussed control methods. The obtained results verify the theoretical analysis and prove the effectiveness of the proposed control of the inverter's input and output powers and battery power regardless of the charging or discharging situation. A real PV panel is used in the grid-tie test of the proposed energy-stored qZSI, which demonstrates three operational modes suitable for application in the PV power system. [ABSTRACT FROM PUBLISHER]

This paper presents a novel snubberless naturally clamped bidirectional current-fed half-bridge isolated dc/dc converter for fuel cell vehicles (FCVs). The proposed converter achieves zero-current switching (ZCS) of the primary-side active semiconductor devices and zero-voltage switching of the secondary-side active semiconductor devices. It is a potential topology for FCVs, front-end dc/dc power conversion for fuel cell inverters, and energy storage. A proposed secondary-modulation clamps the voltage across the primary-side devices (current fed) naturally and eliminates switch turn-off voltage spike concern with ZCS without any additional circuit. This leads to reduced footprints and lower cost. Voltage across the primary-side current-fed devices is independent of duty cycle like conventional current-fed converters but clamped at a reflected output voltage. Therefore, comparatively low-voltage-rating devices with a low on-state resistance are used, introducing low conduction losses and higher efficiency. Steady-state analysis, operation, design, simulation, and experimental results of the proposed converter are reported in this paper. [ABSTRACT FROM PUBLISHER]

This paper presents a compact emergency lamp using light-emitting diodes (LEDs). The goal is to develop a compact and low-cost electronic circuit to drive and control the current of LEDs arranged in a single enclosure. The main advantage of the proposed idea is to use the same equipment in the daily activities, supplied by the ac line, and under a mains failure, supplied by a battery. The proposal also aims to achieve energy saving, higher luminous efficacy, and higher useful life when replacing traditional fluorescent-based emergency lighting systems. The use of the E-27 socket provides the advantage of easy installation, with the simple replacement of the lamp without any change in the electrical wiring. Buck and boost converters were employed in order to supply the LEDs by mains and by battery, respectively. However, the converters are designed in order to work without electrolytic capacitors, which have advantages such as reducing size and cost of the circuit, THD reduction, and increasing the useful life of the driver. The battery can be composed of three rechargeable Ni-MH batteries (1.2 V) or a Li-ion battery (3.6 V). The design complies with the Brazilian and international standards for emergency lighting systems and IEC 61000-3-2. The proposed circuit was implemented, and the experimental results were satisfactory. [ABSTRACT FROM AUTHOR]

The main theme of this paper is to present a new digital-controlled technique for battery charger to achieve constant current and voltage control while not requiring current feedback. The basic idea is to achieve constant current charging control by limiting the duty cycle of charger. Therefore, the current feedback signal is not required and thereby reducing the cost of A/D converter, current sensor, and computation complexity required for current control. Moreover, when the battery voltage is increased to the preset voltage level using constant current charge, the charger changes the control mode to constant voltage charge. A digital-controlled charger is designed and implemented for uninterrupted power supply (UPS) applications. The charger control is based upon the proposed control method in software. As a result, the UPS control, including boost converter, charger, and inverter control can be realized using only one low cost MCU. Experimental results demonstrate that the effectiveness of the design and implementation. [ABSTRACT FROM PUBLISHER]

The planar contactless battery charging system is an emerging technology that can be applied to a wide range of portable consumer electronic products. Beginning with a brief historical background, this paper presents a new single-layer winding array and receiver coil structure with cylindrical ferrite cores for planar contactless battery charging systems. Complying with the “Qi” standard, this design enables multiple devices to be placed and charged simultaneously on the wireless charging pad in a free-positioning manner. The charging flux is totally localized within the covered area between the selected primary winding and the secondary winding inside the load. The electromagnetic characteristics of such winding design are studied in finite-element analysis and confirmed by practical implementation. [ABSTRACT FROM AUTHOR]

This paper presents a prototype of a proton exchange membrane (PEM) fuel-cell hybrid system, with a bus connection set by a dc battery bank and all the power electronics and control needed to manage the system. The system power control is based on analog current control. To choose the topology of the controller, a critical review of all the topologies of analog current controllers for dc/dc converters has been done. This review was necessary because there is no literature found that shows a similar compilation. In the experimental part, the proper functioning of the controlled hybrid system is reflected on one hand and the way to solve the known problem of starvation on the other hand. A very important aspect of the system is its scalability. It can be developed in parallel to implement a whole system that handles power levels higher than the rate power of each single fuel-cell system. [ABSTRACT FROM AUTHOR]

The capacity to store energy in ultracapacitors or double-layer capacitors is about two orders of magnitude greater than that of ordinary capacitors. Also, their capability to receive and transfer power is greater than that of batteries in the same order of magnitude. These characteristics, together with their long life cycle ( > 500 000) and their lack of maintenance work, make them a suitable choice in replacing batteries in pulsed or discontinued power consumption systems. This paper tries to evaluate the possibility to replace batteries with ultracapacitors in Global System for Mobile Communications (GSM)-based remote supervision systems using photovoltaic panels as main power source. [ABSTRACT FROM PUBLISHER]

To obtain zero-current-switching (ZCS) operation, this paper develops a novel soft-switching approach for rechargeable batteries. By inserting an auxiliary switch in series with a resonant capacitor, the proposed topology can obtain a novel ZCS buck dc--dc battery charger and significantly decrease the switching losses in active power switches. The proposed ZCS dc--dc battery charger has a straightforward structure, low cost, easy control, and high efficiency. The operating principles and design procedure of the proposed charger are thoroughly analyzed. The optimal values of the resonant components are computed by applying the characteristic curve and electric functions derived from the circuit configuration. Finally, a prototype charger circuit designed for a 12-V 48-Ah lead acid battery is constructed and tested to confirm the theoretical predictions. The maximum charging efficiency of the proposed topology during the overall charging period is 90.3%. Satisfactory performance is obtained from the experimental results. [ABSTRACT FROM AUTHOR]

Although the use of inductively coupled power transfer (ICPT) systems for electric vehicle battery charge presents numerous advantages, a detailed design method cannot be found in the literature. This paper shows the steps to follow in the optimized design of an ICPT system and the results obtained in their application to the four most common compensation topologies, pointing out the best one in terms of minimum copper mass and proper stability conditions. A new design factor KD is proposed to select the optimum configuration for each topology. Finally, the theoretical results are validated on a 2-kW prototype with a 15-cm air gap between coils. [ABSTRACT FROM AUTHOR]

This paper proposes a simple but effective method of electric brake with energy regeneration for a brushless dc motor of an electric vehicle (EV). During the braking period, the proposed method only changes the switching sequence of the inverter to control the inverse torque so that the braking energy will return to the battery. Compared with the presented methods, the proposed solution simultaneously achieves dual goals of the electric brake and the energy regeneration without using additional converter, ultracapacitor, or complex winding-changeover technique. Since the braking kinetic energy is converted into the electrical energy and then returns to the battery, the energy regeneration could increase the driving range of an EV. In addition to the braking period, the duration of release throttle is also included in the energy-regenerative mechanism such that the EV is similar to engine vehicles having the engine brake. Therefore, the electric brake can improve rider's comfort and enhance the EV's safety. Finally, the feasibility of the proposed method is demonstrated by experimental results. It shows that the driving range of the EV could be increased to about 16.2%. [ABSTRACT FROM AUTHOR]

This paper proposes a method for tracking the maximum power point (MPP) of a photovoltaic (PV) module that exploits the relation existing between the values of module voltage and current at the MPP (MPP locus). Experimental evidence shows that this relation tends to be linear in conditions of high solar irradiation. The analysis of the PV module electrical model allows one to justify this result and to derive a linear approximation of the MPP locus. Based on that, an MPP tracking strategy is devised which presents high effectiveness, low complexity, and the inherent possibility to compensate for temperature variations by periodically sensing the module open circuit voltage. The proposed method is particularly suitable for low-cost PV systems and has been successfully tested in a solar-powered 55-W battery charger circuit. [ABSTRACT FROM AUTHOR]

Abstract-This paper proposes a hybrid fuel cell power system, which consists of a fuel cell, an isolated unidirectional converter, a bidirectional converter, an inverter, and a battery. The fuel cell and the battery are connected to the same voltage bus through an appropriate hybrid full-bridge LLC resonant unidirectional converter and a three-level buck/boost bidirectional converter, respectively. The battery is an auxiliary energy source, powers the load during the system's start state to make it easy for the system to cold start, and provides or absorbs the dynamic power when the load varies and the fuel cell cannot respond immediately, so the system dynamic characteristics are improved. Furthermore, the battery can also provide peak power at overload, so the power rating of the fuel cell can be decreased, which reduces the total system cost. In order to ensure that the system operates with high efficiency, this paper also proposes a power management control scheme, which controls the bidirectional converter operating under buck, boost, or shutdown mode according to the operation condition of the fuel cell and battery, so that the battery can be charged or discharged. The operation of the system during cold start and overload are analyzed in detail. A 1-kW fuel cell power system was built in the laboratory. Experimental results are shown to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

In this paper, a duty-varied voltage pulse-charge strategy (DVVPCS), that can detect and dynamically track the suitable duty of the charge pulse, is proposed to improve the battery-charge performance. To assess the system performance, a prototype of the duty-varied voltage pulse charger (DVVPC) is designed and implemented. Comparing with the standard constant-current and constant-voltage (CC-CV) charge strategy, the charge speed of the proposed DVVPCS is improved by about 14%, while the proposed DVVPCS is improved by about 5% in comparison with the conventional duty-fixed voltage pulse-charge strategy (DFVPCS). The charge efficiency of the proposed DVVPC has been improved by about 3.4% as compared with that of the general CC-CV. In comparison with conventional DFVPCS with D = 50%, the charge efficiency of the proposed DVVPCS is improved by about 1.5%. The results indicate that the DVVPCS can actually provide pulse with suitable duty to charge the battery, and the charge performance is improved. [ABSTRACT FROM AUTHOR]

For hybrid electric vehicles, the batteries and the drive dc link may be at different voltages. The batteries are at low voltage to obtain higher volumetric efficiencies, and the dc link is at higher voltage to have higher efficiency on the motor side. Therefore, a power interface between the batteries and the drive's dc link is essential. This power interface should handle power flow from battery to motor, motor to battery, external genset to battery, and grid to battery. This paper proposes a multi-power-port topology which is capable of handling multiple power sources and still maintains simplicity and features like obtaining high gain, wide load variations, lower output-current ripple, and capability of parallel-battery energy due to the modular structure. The scheme incorporates a transformer winding technique which drastically reduces the leakage inductance of the coupled inductor. The development and testing of a bidirectional flyback dc-dc converter for hybrid electric vehicle is described in this paper. Simple hysteresis voltage control is used for dc-link voltage regulation. The experimental results are presented to show the working of the proposed converter. [ABSTRACT FROM AUTHOR]

In this paper, a reflex charging strategy with the energy recovery function for a bidirectional converter (BC) is proposed to build a novel reflex-based BC (RBC) for increasing the battery charging efficiency in an uninterruptible power supply (UPS). The proposed RBC can provide a reflex charging current profile to charge the battery to obtain a high battery charging efficiency and prolong the battery life cycle. In particular, the negative pulse energy of the reflex charging current profile in the proposed RBC is recovered to reduce the battery charging dissipation. A soft transfer method is also developed in this paper to really erase the spike current in the RBC. A 400 W prototype is designed and implemented to verify the feasibility of the proposed RBC. Compared with a typical bidirectional converter, the battery charging efficiency, the battery charging speed, and the battery thermal deterioration effect are improved by about 10%, 8.8%, and 7%, respectively, with the proposed RBC. [ABSTRACT FROM AUTHOR]

This paper proposes a boost converter with coupled inductors and a buck-boost type of active clamp. In the converter, the active-clamp circuit is used to eliminate the voltage spike that is induced by the trapped energy in the leakage inductor of the coupled inductors. The active switch in the converter can still sustain a proper duty ratio even under high step-up applications, reducing voltage and current stresses significantly. Moreover, since both main and auxiliary switches can be turned on with zero-voltage switching, switching loss can be reduced, and conversion efficiency therefore can be improved significantly. A 200-W prototype of the proposed boost converter was built, from which experiment results have shown that efficiency can reach as high as 92% and surge can be suppressed effectively. It is relatively feasible for low-input-voltage applications, such as fuel cell and battery power conversion. [ABSTRACT FROM AUTHOR]

In this paper, a variable frequency pulse charge system (VFPCS), that can detect and dynamically track the optimal charge frequency, is proposed to improve the battery-charge response. To assess the system performance, a prototype of the VFPCS for 600-mAh lithium-ion battery is designed and implemented. Compared with the standard constant-current and constant-voltage charge system, the charge speed of the proposed VFPCS is improved above 24%, while the proposed VFPCS is improved above 10% compared with the conventional fixed-frequency pulse charge system. The results indicate that the VFPCS can actually provide pulse with optimal frequency to charge the battery and the charge response is improved. [ABSTRACT FROM AUTHOR]

This paper presents a method for operating cascaded multilevel inverters when one or more power cells are damaged. The method is based on the use of additional switches in the power circuit to bypass the faulty cell. To control the cells, the angle of phase shifting in the carrier signals is modified according to the number of operating cells, to minimize the load voltage distortion, when the inverter operates in failure mode. The reference signals of the pulsewidth-modulation modulators are also modified to increase the output voltage. Simulation and experimental results show the effectiveness of this method, which significantly increases the reliability of the drive. [ABSTRACT FROM AUTHOR]

This paper presents a method for achieving individual electrochemical cell balancing by using a cascaded full-bridge multilevel converter where a single electrochemical cell is connected to each converter module. As a result, balancing at cell level is possible without additional circuitry, making this topology ideal for long-service-life grid storage and applications using second-life cells where the cells are inherently poorly matched. In order to estimate the relative state of charge between cells, the control flexibility of the multilevel converter is used to remove each cell from the current path without interrupting the operation of the system. This process eliminates the effect of the internal cell resistance and fast transient electrochemical phenomena, and therefore, the measured voltage serves as a high-quality “pseudo-open-circuit” voltage measurement. The proposed balancing strategy is validated using a 25-level cascaded full-bridge multilevel converter prototype for the individual balancing of 12 lithium polymer cells, during consecutive charging and discharging cycles. Successful balancing to within 5 mV of open-circuit voltage is observed between cells with 45% difference in nominal capacity and 55% initial state-of-charge variation. [ABSTRACT FROM PUBLISHER]

This paper presents a new configuration for integrated on-board battery chargers of electric vehicles (EVs) incorporating symmetrical six-phase machines. The configuration proposes an exclusive utilization of a nine-switch converter (NSC) along with the machine windings during both propulsion and charging of EVs. The proposed configuration has the advantage of employing a reduced number of components in both the EV (on-board) and charging station (off-board), with the privilege of avoiding machine electromagnetic torque production during charging/vehicle-to-grid (V2G) mode of operation. During charging/V2G mode, the NSC is turned into a conventional three-phase pulse width modulation rectifier and is directly connected to the three-phase mains through the machine windings. Conventional three-phase transformers can be employed for galvanic isolation. Switching between propulsion and charging modes is carried out using a simple hardware reconfiguration. Control schemes for both propulsion and charging/V2G modes are elaborated, along with the principles of operation of the NSC. Experimental results are provided to validate the theoretical deductions for the different operating modes. [ABSTRACT FROM PUBLISHER]

The photovoltaic (PV)-based battery switch station (BSS) is one of typical integration systems to implement a solar-to-vehicle system. The charging strategy is important for the operation of the PV-based BSS. Generally, instant charging strategy for swapped electric vehicle (EV) batteries can keep the availability of battery-swapping service at a high level. However, it is always accompanied with the possibility of bringing a negative effect on the utilization of PV energy. The contribution of this paper is mainly on a novel charging strategy for the PV-based BSS considering the service availability and self-consumption of the PV energy. First, considering the features of the PV-based BSS, evaluation indexes for the operation performance are defined, including the availability of battery-swapping service, self-consumption of the PV energy, and operation profit. Second, the charging strategy is proposed, including a battery-swapping service model and a power distribution model. In order to guarantee the service availability, the battery-swapping service model is used to decide the lower limit of charging power based on short-term forecasting results of EV requirements. The power distribution model is obliged to dispatch the charging power supplied by the PV system and power grid. Finally, in the case study, the operation of the BSS is simulated with the instant charging strategy and the proposed strategy under different scenarios. From the analysis of results, the proposed strategy can effectively improve the self-consumption of PV energy with the premise of guaranteeing the availability of the battery-swapping service. [ABSTRACT FROM PUBLISHER]

The development of an auxiliary power unit (APU) with 110 V/60 Hz output from conventional battery, laptop computer battery pack, or other available dc sources and its robust controls are presented in this paper. First, a front-end current-fed push-pull dc/dc converter is designed and implemented. It is used to establish the boosted and well-regulated dc-link voltage for the followed inverter. The quantitative designed feedback controller is augmented with a novel robust tracking error cancellation scheme (RECC) to achieve the desired regulation performance. Then, a full-bridge single-phase pulse-width modulated inverter is established to yield 110 V/60 Hz source for emergency use. In treating the inverter waveform control, the causes of waveform distortion under nonlinear loads are explored. Then a novel robust model following control scheme is proposed accordingly. In the proposed control scheme, the simple model following controller is augmented with a RECC. Theoretic bases of all the proposed control schemes are derived thoroughly. The simulation and experimental evaluations indicate that the developed APU possesses good output voltage waveform under unknown and nonlinear loads. [ABSTRACT FROM PUBLISHER]

Proven methods of battery diagnosis exist in the industry based on the measurement of the internal impedance from cell to cell. Nevertheless, these maintenance methodologies are incompatible with the operation of the industrial traction batteries due to great variations of ambient temperature, the paralyzation needed, and access difficulty. This paper benefits from the tested stationary standards of maintenance and includes innovative proposals in order to take into account the battery operating conditions. The difficult accessibility of industrial traction batteries finds a solution in a quicker and safer method based on the measurement of a group of cells simultaneously. This article also shows an algorithm that establishes the mathematical relation between the impedance of simultaneous cells and the temperature for any model of lead–acid battery. This algorithm is valid throughout the working temperature range of the battery. From an industrial-maintenance standpoint, the model presented can assess, at any time, the state of the acceptance and rejection of the battery modules by comparing their module impedance values. The maintenance meets the international standards for the measurement of the impedance of a group of cells under changing conditions of temperature. This new maintenance method optimizes the quality and time of the inspection process, enhancing the availability and reliability at a low cost. [ABSTRACT FROM PUBLISHER]

Residential energy consumption accounts for 21% of the total electricity use in the United States. Unfortunately, research indicates that almost 41% of this power is wasted. Changing the way that consumers use energy may be important in reducing home energy consumption. This paper looks at whether the implementation of certain real-time energy monitors has an impact on the residential rate of energy consumption in a metropolitan area with relatively low electricity rates. In the following case study, 151 Omaha residences were equipped with two variants of the Aztech In-Home Display (Aztech) as well as the Blue Line Power Cost Monitor (PCM) real-time energy monitors for a period of 16 months. The results of the data, 30 days after installation, revealed a statistically insignificant reduction of 12% in mean electrical consumption in houses equipped with a PCM and no reduction in mean consumption in homes using either variants of the Aztech device when compared to a randomly selected control sample. However, they proved effective in the short term if utilized by utilities for mass distribution to foster awareness among participating residents of their own patterns of residential electricity consumption and on the environmental impacts of energy saving. [ABSTRACT FROM AUTHOR]

In this paper, a new three-level (3L) converter is presented. It is called 3L Vienna neutral-point-clamped (3L-VNPC) converter and consists of two stacked high-frequency (HF) commutation cells working with a shared power device. The HF cells are connected to a single-phase switched bridge controlled at low frequency. The 3L-VNPC topology is extended to 3L active VNPC (3L-AVNPC) concept, which is generalized for five levels (5L) and N odd voltage levels (N \L). The proposed multilevel converters can be seen as two cascaded voltage stages. The high-voltage stage is specific to the single-phase switched bridge, while the low-voltage (LV) stage corresponds to the stacked HF cells with shared power devices. The new concept AVNPC is a useful and suitable solution for medium-voltage applications, where small modulation index (M) is as crucial as large M. The analyses of the new converters are verified by simulations both for 3L and for 5L topologies, and their features are generalized for N\L. Experimental results for single-phase 3L-AVNPC converter on an LV test bench are also provided to validate the proper operation of the new concept. [ABSTRACT FROM AUTHOR]

This paper develops an integrated driving/charging switched reluctance motor (SRM) drive for electric vehicles using off-the-shelf three-phase intelligent power modules (IPMs). Five legs of two IPMs are employed to construct the four-phase SRM modified Miller converter. Moreover, its front-end dc/dc boost converter is formed by the remaining one leg to boost the dc-link voltage from a battery. Proper current and speed control schemes are designed to yield satisfactory driving performance. In particular, the performance under higher speed is enhanced by the boosted dc-link voltage and the advanced shift of commutation instant. In idle case, some imbedded IPM power devices and SRM windings are arranged to form a buck-boost type or a buck-type switch-mode rectifier (SMR) for charging the battery from a utility with good charging control characteristics and a line drawn power quality. The rating derivations, performance analyses, and controller designs for these two SMRs are performed in detail. All constituted circuit components of the charger are naturally placed onboard; only the insertion of a power cable to the ac source socket is needed. A common digital signal processor is used to realize all control schemes fully digitally, and their control performances are demonstrated experimentally. [ABSTRACT FROM AUTHOR]

This paper proposes a method of sharing power/energy between multiple sources and multiple loads using an integrated magnetic circuit as a junction between sources and sinks. It also presents a particular use of the magnetic circuit as an ac power supply, delivering sinusoidal voltage to load irrespective of the presence of the grid, taking only active power from the grid. The proposed magnetic circuit is a three-energy-port unit, viz.: 1) power/energy from grid; 2) power energy from battery–inverter unit; and 3) power/energy delivery to the load in its particular application as quality ac power supply (QPS). The product provides sinusoidal regulated output voltage, input power-factor correction, electrical isolation between the sources and loads, low battery voltage, and control simplicity. Unlike conventional series–shunt-compensated uninterruptible power supply topologies with low battery voltage, the isolation is provided using a single magnetic circuit that results in a smaller size and lower cost. The circuit operating principles and analysis, as well as simulation and experimental results, are presented for this QPS. [ABSTRACT FROM AUTHOR]