Charging Limit Research Articles

An investigation of the electrical dynamics in electroactive polymer transducers with resistive electrodes

To pursue a variable-capacitance working principle, transducers based on soft electroactive polymers (EAPs) need deformable electrodes that match the compliance and stretchability of the EAP polymeric substrates. A variety of manufacturing procedures are available to create conductive materials that can achieve this, including solutions that can provide remarkably low resistivity. However, the simplest and most feasible options often involve the use of particle-filled (e.g. carbon-filled) polymer composites, which, while easy to produce, tend to exhibit relatively high resistivity. This high level of resistivity, combined with the inherent capacitance of EAP transducers, introduces dynamic effects in the devices electrical activation, which may affect performance. This paper investigates the impact of electrode resistivity on the electrical dynamics of EAP devices, combining continuum models and experimental validations. We use a continuum generalisation of known resistive-capacitive (RC) transmission line models to accurately predict voltage gradients on the surfaces of electrostatic transducers subject to rapidly varying voltages. We then present an experimental validation by measuring the spatial voltage distributions over carbon-based polymeric electrodes of dielectric elastomer (DE) transducers, and find a good agreement with our model predictions. We use our validated model to provide general estimates of the typical charging time and limit working frequency ranges of DE devices as a function of their dimensional scale and electrode sheet resistance. Our model provides useful indications for designing compliant electrodes in EAP transducers given target performance, or to understand the working limits of devices with given geometry and dielectric-electrode properties.

Electric Vehicle Charging Scheduling Optimization Method Based on Improved Ant Colony

The influx of electric vehicles significantly impacts the power grid. In the process of power grid operation, the operation of charging and discharging of electric vehicles can be used to dispatch the load of power grid operation. The optimization method of charging and dispatching electric vehicles based on improved ant colony is studied. Pheromones generated during the charging of the electric vehicle are obtained, and the charging limit range of the battery is delimited. The dynamic window constructs the charging scheduling model improved ant colony algorithm, and the optimal charging path is selected to complete the scheduling method design. The experimental results show that the proposed method can adjust the charging and discharge in the period of valley price and peak price, play the role of peak clipping, and realize the load regulation in different periods, which has application value.

An energy harvesting technology controlled by ferromagnetic resonance

We have successfully demonstrated electrical charging using the electromotive force (EMF) generated in a ferromagnetic metal (FM) film under ferromagnetic resonance (FMR). In the case of Ni80Fe20 films, electrical charge due to the EMF generated under FMR can be accumulated in a capacitor; however, the amount of charge is saturated well below the charging limit of the capacitor. Meanwhile, in the case of Co50Fe50, electrical charge generated under FMR can be accumulated in a capacitor and the amount of charge increases linearly with the FMR duration time. The difference between the Ni80Fe20 and Co50Fe50 films is due to the respective magnetic field ranges for the FMR excitation. When the FM films were in equivalent thermal states during FMR experiments, Co50Fe50 films could maintain FMR in a detuned condition, while Ni80Fe20 films were outside the FMR excitation range. The EMF generation phenomenon in an FM film under FMR can be used as an energy harvesting technology by appropriately controlling the thermal conditions of the FM film.

Performance of ACO-MPPT and Constant Voltage Method for Street Lighting Charging System

Electricity consumption continues to increase every year. Alternative energy source such as solar panel have been easily developed and do not cause pollution. By utilizing the sun's rays on its surface, solar panels can produce electricity depending on the level of surface temperature and the conditions of the intensity of solar radiation. Most street lighting electrical systems with conventional solar panels have minimal output power due to not having the Maximum Power Point Tracking (MPPT) function. In addition, the absence of a charging function results in an uncontrolled voltage magnitude affecting the parameters of electrical energy (accumulators), especially when the accumulator's State of Charge (SOC) approaches the full charging limit. Therefore, a system of street lighting is used which is capable of carrying out MPPT functions and charging functions with an electrical system that uses a CUK type DC-DC Converter. Ant Colony Optimization (ACO) algorithm as MPPT control, and the Constant Voltage (CV) method as charging control with measurements, SOC uses the coulomb counting method. The performance has proven to optimize a 200 Watt-peak solar panel power output up to 18.92 Watts, maintain a voltage value with a maximum error difference of 2% only, which can read the battery SOC accurately.

A Proposed Strategy for Power Management of a Standalone Wind Energy Conversion System with Storage Battery

Several strategies have been suggested to optimize power extracted from the Standalone Variable Speed Wind Energy Conversion System (SVSWECS) using a Squirrel Cage Induction Generator (SCIG). Where, many of them use the battery as a storage unit for future use. However, the latter is assumed as an ideal component and that no maximum charging or critical limit. With the considered strategy, the generated wind power can be managed using a fast and reliable fully rugged electrical control. Indeed, the use of reliable Power Management and Control (PMC) algorithm where the battery current is well controlled. However, this solution allows maintaining the system operation in two stable modes.The considered system consists of an SCIG connected mechanically to the wind turbine through a gearbox, and electrically through a PWM rectifier to the DC bus capacitor, the latter is connected to the load and the battery through a PWM inverter and buck-boost converter respectively. In this paper, to approach the system to reality, a new PMC is proposed using a purely reliable electrical control. The Direct Torque Control (DTC) is used. The latter is combined with the Maximum Power Point Tracking (MPPT) technique and the State Of Charge (SOC) of battery. The important key of the proposed control strategy are the SOC and the sign of the difference between the generated and the demanded powers. The obtained simulations results are assessed and carried out using MATLAB/Simulink package and show the effectiveness and the performance of the proposed algorithm.

Polyaniline supercapacitor electrode and carbon fiber graphene oxide: Electroactive properties at the charging limit

Electroactive materials have presented increasingly relevant application potentials as energy storage, because of the use of 5G technologies, artificial intelligence, IoT and batteries for electric vehicles. The objective of this work was to evaluate their electroactive properties in different potential applications and to test the electrode charge limit for energy storage devices. Structural carbon fiber composite materials coated by electrochemical synthesis of polyaniline with graphene oxide were obtained. The electrodes were characterized by GCD (with and without cutoff), FEG, FTIR, Raman, CV, EIS and 4 probes. The electrodes can be classified with supercapacitive properties according to the Ragone Diagram and applied to different potential variations reaching a charging limit (potential limit that stores the largest amount of charge). Mapping of specific power and energy during cycling reveals that the GO electrode confers structural stability to the PANI and maintains the material’s electroactive properties elevated over 500 cycles.

EDA-Based Charging Algorithm for Plug-In Hybrid Electric Vehicle to Shift the Peak of Power Supply

This paper proposes a charging algorithm which is based on the Estimation of Distribution Algorithm (EDA) for Plug in Hybrid Electric Vehicle (PHEV). The proposed algorithm shifts the peak of power supply, satisfies the requested State of Charge (SoC [%]), and minimizes the charging cost. The proposed algorithm uses flexible weight for charging and upper charging limit to each PHEV to minimize the charge amount in peak time. The simulation result shows that the proposed algorithm shifts the peak of power supply in commute time zones, satisfies SoC of 93% PHEVs, and reduces charging cost by 31% compared with conventional EDA algorithm.

Impedance Diagnostic for Overcharged Lithium-Ion Batteries

We use electrochemical impedance spectroscopy (EIS) to monitor the resistance increases associated with Li-ion batteries during and after overcharge. EIS is commonly used to measure the resistance within a Li-ion cell and can show changes in resistance behavior originating from chemical and electrochemical reactions occurring within bulk electrodes, electrolyte, and along electrode/electrolyte interfaces [1]. The physical processes in electrochemical cells have different time constants or effective capacitances, which result in different frequency responses [2]. We report the impedance characteristics for overcharged batteries are markedly different from those of the healthy batteries. At 500 Hz, the results are independent of state of charge for healthy batteries, and grossly different for overcharged batteries [3]. The changes at 500 Hz are not coincidental, as this frequency responsive to the cell passivation layers that form upon overcharge. From the results, we recommend a singlepoint impedance-based diagnostic tool for monitoring battery health. Commercial Li-ion prismatic cells (Full River 10 to 300 mAh) are used for these experiments. EIS measurements were collected using a Solartron SI 1260 impedance gain-phase analyzer driven by an EG&G PAR263A potentiostat. Impedance data were collected under open circuit conditions using a ±10 mV amplitude perturbation between 50 kHz and 10 mHz at various voltages during charge, overcharge and discharge. The upper limit for the charge voltage ranged from 4.2 V to 5.0 V, while the discharge voltage cutoff was held constant at 2.8 V throughout all experiments. EIS data were collected and analyzed by ZPlot and ZView software packages (Scribner Associates Inc.). The batteries were charged and discharged at constant 1C rates (30 mA) at approximately 23°C. Repeated charge/discharge (2.8–4.2 V) and overcharge/discharge (2.8 – 4.4, 4.6, 4.8, 5.0 V) data were measured using a Maccor Series 4300 battery tester. Overcharged LiCoO2|C cells have drastically different impedance spectra as compared to properly operated ones (charged between 2.8 – 4.2 V). A soft overcharge to 4.4 V results in small changes in the impedance spectrum compared to the recommended 4.2 V upper charging limit. When overcharged above 4.4 V, the impedance characteristics change dramatically. The shapes of the impedance spectra irreversibly change upon discharge after a severe 5.0 V overcharge and no longer resemble the impedance spectra measured for the battery charged to 4.2 V (see reference 3). This irreversibility in the impedance response for overcharged Li-ion cells is most pronounced at 500 Hz (Fig 1). A single overcharge to 4.6 V causes the battery impedance at 500 Hz to drop significantly, reflecting a change in the structure of the electrode passivation layers. With further overcharge cycles, the battery impedance at 500 Hz increases, reflecting an increase in the cell resistance, and the first steps toward an overheating battery. These trends are independent of battery sizes from 10 to 300 mAh, but more work is needed to determine these trends across different chemistries (i.e. LiFePO4 cathodes), battery packs, and for cells operating at different temperatures. This work points to a simple prognostic and diagnostic for the safe operation of Li-ion batteries, and also sheds some information on the causes of overcharge failure in batteries.

Assessment charges are a backward step.

Do nurses realise that the single assessment process for long-term care will be introduced in October this year for older people and in April 2002 for all other care groups? NHS nurses will be expected to assess nursing and personal needs using purely financial criteria and with a charging limit of £100 per week for nursing interventions.

Sensitivity enhancement of electrospray ionization-MS for aqueous solutions in the corona-assisted cone-jet mode

An experimental study is reported of the sensitivity obtained for the electrospray ionization of aqueous solutions in two different cone-jet modes. Six different polypeptides varying in molecular weight from ~600 to ~ 12 000 Da were analyzed using a quadrupole mass spectrometer. The sensitivity comparison suggests that more than an order of magnitude enhancement in signal intensity can be achieved in some cases by simply shifting the electrospray operation from the classic cone-jet mode to the corona-assisted cone-jet mode. The sensitivity enhancement in the corona mode spray appears to be independent of both liquid flow rate and sample molecular weight, suggesting that droplet field charging by the corona discharge is the dominant process. Comparison at the field charging limit and the Rayleigh limit indicates that the droplet charge can be effectively increased to the field charging limit for corona mode electrosprays of aqueous solutions at low flow rate.

Surface charging limit for a woven fabric on a ground plane

Abstract This paper investigates the problem of depositing the maximum possible charge on a sheet of porous material, such as cloth, using a corona discharge. In the experiments, 50 to 75 μm-thick samples of nylon parachute fabric of varying porosity were charged over a ground plane using corona ions generated by a pin array energized at 6 kV – 9 kV dc and 0.5 cm gap spacing. The cloth exhibited a material-dependent maximum surface potential that was independent of the potential of the corona electrodes. This characteristic maximum surface potential was larger for low-porosity fabrics (tighter weave pattern), reaching a high of approximately 600V for 65 μm-thick, “zero porosity”, calendared ripstop nylon. Maximum surface potentials on the order of 200–500 V were observed on higher-porosity, “standard-issue” parachute fabrics of similar thicknesses. The experiments suggest a fundamental limit to surface charge that depends on the properties of the cloth, but not on the corona charging voltage. The observed results can be explained, in part, by a back ionization discharge mechanism that limits the indefinite build up of surface charge. The onset of back ionization is predicted from the Paschen breakdown curve and the weave geometry of the cloth. Breakdown field strengths inside the pores of the material were estimated using a simple dielectric layer model.

On the Manufacturing method of Yonkontya (Part 1)

1. The manufacturing method of Yonko-ntya was examined with the green leaves of Tamamidori and domestic varieties plucked with shears in the first, second and third seasons in 1958.2. It was recognized that a similar process to the ordinary black Guri tea making was the best for making Yonkontya among the three methods tested.3. When the raw material. was common class leaves (shearsplucked), decreasing feed rate of the seccndary tea drier or application of the secondary rolling tea drier in place of the former machine had no good effect.4. Accordingly, in the final drying process, it was indispensable to feed a considerable large charge into the rotating drier.5. But the increasing charge accompanied a deterioration of the qualities of tea inevitably, so it should be very necessary not to exceed the charging limit in the secondary tea drier.