A Robust Single-Sensor MPPT Strategy for Shaded Photovoltaic-Battery System

A robust single-sensor global maximum power point tracking(MPPT)strategy based on modern optimization for photovoltaic systems considering shading conditions is proposed in this work.The proposed strategy is designed for battery charging applications and direct current(DC)microgrids.Under normal operation,the curve of photovoltaic(PV)output power versus PV voltage contains only a single peak point.This point can be simply captured using any traditional tracking method like perturb and observe.However,this situation is completely different during the shadowing effect where several peaks appear on the power voltage curve.Most of these peaks are local with only a single global.This condition leads to the incapability of traditional tracking approaches to extract the global peak power due to their inability to distinguish between the local and global peak points.They are trapped in the first peak point even when the point is local.Therefore,global tracking approaches based on modern optimization are highly required.A recent marine predators algorithm(MPA)has been used to solve the problem of tracking the global MPP under shadowing influence.Different shadowing scenarios are used to test and evaluate the performance of MPA based tracker.The obtained results are compared with particle swarm optimization(PSO)and ant lion optimizer(ALO).The results of the comparison con-firmed the effectiveness and robustness of the proposed global MPPT-MPA based tracker over PSO and ALO.

Vehicle-to-grid power system services with electric and plug - in vehicles based on flexibility in unidirectional charging

With proper power scheduling and dynamic pricing,a unidirectional charger can provide benefits and regulation services to the electricity grid,at a level approaching that of bidirectional charging.Power scheduling and schedule flexibility of electric and plug-in hybrid vehicles are addressed.The use of electric vehicles(EVs)as flexibility resources and associated unidirectional vehicle-to-grid benefits are investigated.Power can be scheduled with the EV charger in control of charging or via control by a utility or an aggregator.Charging cost functions suitable for charger-and utility-controlled power scheduling are presented.Ancillary service levels possible with unidirectional vehicle-to-grid are quantified using sample charging scenarios from published data.Impacts of various power schedules and vehicle participation as a flexibility resource on electricity locational prices are evaluated.These include benefits to both owners and load-serving entities.Frequency regulation is considered in the context of unidirectional charging.

Influence of the Electrical Vehicle Charging on the Grid Harmonic

This paper described the impact of the electrical vehicle（EV） charging on the grid harmonic. In view of the randomness of the EV charging process, the harmonic admittance matrix method and superposition method were used to build the single and multiple EVs charging simulation model. By using Matlab as a simulation tool, we analyzed harmonic currents of single and multiple EVs chargers. The results show that the harmonic ratio is beyond the scope of the national harmonic standard. Finally a parallel hybrid active filter（PHAPF） was introduced for governance of harmonic.The experimental results show that net side harmonic currents are significantly reduced by using the PHAPF and meet the national standard GB/Z17625.6-2003 regulations limit.

Battery Charger for Electric Vehicles based on a Wireless Power Transmission

In this paper,the case of a battery charger for electric vehicles based on a wireless power transmission is addressed.The specificity of every stage of the overall system is presented.Based on calculated and measured results,relevant capacitive compensations of the transformer and models are suggested and discussed in order to best match the operating mode and aiming at simplifying as much as possible the control and the electronics of the charger.

Multi-objective Optimal Operation of Centralized Battery Swap Charging System with Photovoltaic

Electric vehicles(EVs)are widely deployed throughout the world,and photovoltaic(PV)charging stations have emerged for satisfying the charging demands of EV users.This paper proposes a multi-objective optimal operation method for the centralized battery swap charging system(CBSCS),in order to enhance the economic efficiency while reducing its adverse effects on power grid.The proposed method involves a multi-objective optimization scheduling model,which minimizes the total operation cost and smoothes load fluctuations,simultaneously.Afterwards,we modify a recently proposed multi-objective optimization algorithm of non-sorting genetic algorithm III(NSGA-III)for solving this scheduling problem.Finally,simulation studies verify the effectiveness of the proposed multi-objective operation method.

Cascaded Multilevel Inverter Based Power and Signal Multiplex Transmission for Electric Vehicles

Power&signal multiplex transmission(P&SMT)is a technique that uses power electronic circuits for communication signal transmission.In this paper,a three-phase cascaded multilevel inverter-based P&S MT system is proposed.The proposed method can transmit communication signals without using a Controller Area Network bus,thereby reducing the wiring cost of the conventional electric vehicle(EV)communication system.The designed system can achieve motor speed regulation and battery balance discharging for EVs.With the combined pulse width modulation scheme and frequency shift keying method,both power and communication signals are transmitted successfully in a simulation model implemented in Matlab/Simulink.By evaluating the bit error rate of the transmitted signal,the maximum signal rate of the proposed system is determined as 600 bit/s.

Analysis and Comparison of Two Wireless Battery Charger Arrangements for Electric Vehicles

The paper deals with wireless battery chargers(WBCs)for plug-in electric vehicles(PEVs)and analyzes two arrangements for the receiver of a series-series resonant WBC.The first arrangement charges the PEV battery in a straightforward manner through a diode rectifier.The second arrangement charges the PEV battery through the cascade of a diode rectifier and a chopper whose input voltage is kept constant.Figures of merit of WBCs such as efficiency and sizing factor of both the power source and the transmitter/receiver coils are determined.Afterwards,they are discussed and compared with reference to the case study of WBC for an electric city car.A proposal to optimize the efficiency of the second arrangement by a suitable selection of the chopper input voltage is presented.Measurements on the efficiency of the two arrangements are included to support the theoretical results.

Energy Management Strategy for Hybrid Electric Vehicle Based on System Efficiency and Battery Life Optimization

A novel method to calculate fuel-electric conversion factor for full hybrid electric vehicle（HEV）equipped with continuously variable transmission（CVT）is proposed.Based on consideration of the efficiency of pivotal components,electric motor,system efficiency optimization models are developed.According to the target of instantaneous optimization of system efficiency,operating ranges of each mode of power-train are determined,and the corresponding energy management strategies are established.The simulation results demonstrate that the energy management strategy proposed can substantially improve the vehicle fuel economy,and keep battery state of charge（SOC）change in a reasonable variation range.

Comprehensive Review and Analysis of Two-element Resonant Compensation Topologies for Wireless Inductive Power Transfer Systems

Wireless power transfer(WPT)is gaining much attention for battery charging of electric vehicles(EVs).Resonant WPT systems play a crucial role in achieving efficient power transfer from source to load.An overview of two-element resonant compensation techniques and their characteristics under various operating conditions are presented.Also the converter and control strategies used for different topologies are reviewed.The behavior of the performance factors are evaluated against the operating conditions and compared for the different topologies.

Room-temperature extraction of individual elements from charged spent LiFePO_(4)batteries

Recycling millions of metric tons of spent LiFePO_(4) batteries would benefit human health while reducing resource depletion and environmental pollution.However,recovering individual elements from the spent batteries without generating waste is challenging.Here,we present a distinctive approach for recycling spent LiFePO_(4) batteries at room temperature,where water is the only leaching agent consumed.FePO_(4) and lithium intercalated graphite act as a precursor material for selectively extracting lithium,iron,and phosphorus through charging the LiFePO_(4) batteries to the delithiated state.NaOH solution extracted Fe from FePO_(4) within 30 min and regenerated without consumption,similar to a catalyst.Under the optimal leaching conditions(1 mol·L^(-1) NaOH,0.5 h,NaOH/Fe molar ratio of 4.5),Fe and P leaching efficiencies achieved 89.1%and 99.2%,respectively.The methodology reflected in this research reduced the material cost per kg cathode material to a fraction of previously published reports,only occupies 6.13%of previous reports.In addition,the method improved the battery recycling revenue calculated by the EverBatt model by 2.31 times and 1.94 times over pyrometallurgical and hydrometallurgical methods.The proposed method allows for the convenient recovery of the elemental components of spent LiFePO_(4) batteries.