Constant Voltage Circuit Research Articles

Accelerated Failure in Li[Ni0.5Mn0.3Co0.2]O2/Graphite Pouch Cells Due to Low LiPF6 Concentration and Extended Time at High Voltage

Li[Ni0.5Mn0.3Co0.2]O2/graphite pouch cells were cycled using protocols that included 24 h spent at high voltage (≥ 4.3 V) under constant voltage or open circuit conditions to accelerate failure. Compared to traditional cycling, failure was reached up to 3.5 times faster. When this protocol was applied to cells containing low LiPF6 concentrations (≤ 0.4 M) failure was achieved up to 17.5 times faster than traditional cycling with normal LiPF6 concentrations. This represents a time improvement on the order of years and therefore can be used as a high-throughput screening method. Failure mechanisms for cells containing a range of LiPF6 concentrations undergoing these aggressive protocols were investigated using charge-discharge cycling, impedance spectroscopy (including symmetric cell analysis) and isothermal microcalorimetry. Long times at high voltage rapidly increase positive electrode impedance but do not seem to consume lithium inventory. The use of lower LiPF6 concentrations does not seem to introduce new failure mechanisms but makes cells less tolerant to positive electrode impedance growth. The utility of this method is demonstrated by screening cells with a variety of electrolyte additive combinations. Fewer than 3 months were required to distinguish cells containing 1% lithium difluorophospate as superior to cells with other additive combinations.

High frequency temperature fluctuation measurements by Rayleigh scattering and constant-voltage cold-wire techniques

The thermal inertia of sensors drastically limits the measurement of the temperature fluctuations in the high-frequency range. This issue is often addressed using cold wire techniques with dedicated corrections. In this study, three methods are employed to compensate high-frequency attenuation, and the correction of the end losses, are evaluated for four wires with different aspect ratios and diameters. The fidelity of the corrected measurements is assessed by comparing the spectra of temperature fluctuations obtained with the cold wires operating in a constant voltage circuit, to those derived from optical measurements. The latter method is based on Rayleigh scattering and is in principle not affected by thermal inertia as it relies on molecular light scattering. Two flows presenting high levels of temperature fluctuations are considered. Namely, the wake of a heated cylinder, and a mixing layer between two jets in co-flow and at different temperatures. These two configurations allow exploring cold wire performances at high frequency, and show that precise measurements can be performed up to 10 kHz with a wire $$1\,\upmu \hbox {m}$$ in diameter.

Dental Implant Electrical Stimulation Healing Device

There is an electrical stimulation device for dental implant healing, which is designed for dental patients who have been received an implant in their jaws during the three months of healing period. The device consists of adjustable constant current (or constant voltage) circuit, power supply (including DC or external AC power supply and transformer), MCU(Microcontrollers), wire and electrode, electrode fixed and connecting device, control panel and shell. When the dental implants have been implanted, the instrument facilitates osseointegration between the implant and the alveolar bone and healing of the implant and gingival tissue. There is the most advantage that we can adjust the corresponding constant voltage (50-1000mV) or constant current (10-200mA)and the loading time(10-60min) depending on the patient's alveolar bone condition.

Experimental study on supersonic film cooling on the surface of a blunt body in hypersonic flow

The experimental study focuses on the heat flux on a double cone blunt body in the presence of tangential-slot supersonic injection into hypersonic flow. The tests are conducted in a contoured axisymmetric nozzle with Mach numbers of 7.3 and 8.1, and the total temperature is about 900 K. The injection Mach number is 3.2, and total temperature is 300 K. A constant voltage circuit is developed to supply the temperature detectors instead of the normally used constant current circuit. The schlieren photographs are presented additionally to visualize the flow and help analyze the pressure relationship between the cooling flow and the main flow. The dependence of the film-cooling effectiveness on flow parameters, i.e. the blow ratio, the convective Mach number, and the attack angle, is determined. A semi-empirical formula is tested by the present data, and is improved for a better correlation.

Design of Digital Control DC Voltage Source Based on AT89C52 MCU

the system to DC voltage source as the core, AT89C52 MCU as the main controller, the output voltage to set the DC power supply through the keyboard, with a step function voltage to reality, the actual output value. This design is divided into four modules: SCM control and display module, digital to analog (D/A) conversion module, a constant voltage source module, output module. MCU control module as the core, the input signal is converted to digital quantity output; constant current source module voltage D/A conversion to analog conversion into constant pressure through a constant voltage circuit. The system has good reliability, high precision.

Consideration of Energy Storage Circuits for Magnetic Energy Harvesting

In this paper, we propose an energy storage circuits for magnetic energy harvesting. We successfully harvested 104 mW from applied magnetic field of 90 μT at 60 Hz. This magnetic field is smaller than the value that ICNIRP2010 guideline provided. In order to use effectively the harvested energy, we consider energy storage circuits. Because an increase in an output voltage produced an increase in the storage energy, we use Cockcroft-Walton circuit for transform AC to DC voltage and step up voltage. Our proposed storage circuit consists of Cockcroft-Walton circuit, capacitor, and constant voltage circuit. It was found that the storage energy was proportional to the square of number of Cockcroft-Walton circuit steps. From experiments, we successfully demonstrate that our energy harvesting device can provide an energy of 1 J for magnetic flux density of 5.43 μT.

제어 방식에 따른 20 W급 LED Converter 설계 및 분석

In this paper, by designing 20 W class driving circuit for driving high-power LED (Light Emitting Diode), we are going to comparatively carry out the analysis of characteristics for power circuit according to each design method. In this case, 200 V 60 Hz was performed as input data. The electrical characteristics such as voltage, current and ripple are checked for constant current circuit and constant voltage circuit in the LED module. In addition, as the ripple has an influence on illumination of LED light, low temperature working (-20 []) and high temperature working(80 []) are measured to make sure the ripple characteristics in accordance with temperature. In low temperature operation -20 [] measurements, both constant current circuit and constant-voltage circuit were less impacted on input fluctuation, whereas in the high temperature operation 80 [], current voltage in constant voltage circuit was surge after 430 [hour]. Voltage current ripple of constant current circuit was much less than constant voltage circuit, therefore we can show that constant current circuit is more stable.

124 形状記憶合金を用いた人工尿道括約筋システムの開発研究(生物医学工学における計測と制御)

This paper presents the development of mechanical SMA urethral valve with transcutaneous energy transformer, which is supplied by batteries. In order to realize the portable type, the constant voltage circuit and the sine wave oscillation circuit are examined through the laboratory tests on cycling characteristics, and so on. From the experimental results, it is seen that the stabilized operation is enabled by introducing the constant voltage circuit between the driving batteries and the other primary circuits, and the efficiency upgrading of electric power transmission was realized by utilizing the sine wave oscillation.

High Power Characterization of Piezoelectric Materials

Three techniques for measuring high voltage/power piezoelectric properties, which have been developed recently, are compared: a voltage-constant piezoelectric resonance method, a current-constant piezoelectric resonance method, and a pulse drive method. The conventional resonance method with a constant voltage circuit exhibits significant distortion (or a hysteresis) in the resonance frequency spectrum under a high vibration level due to large elastic non-linearity, which limits precise determination of the electromechanical coupling parameters. To the contrary, the resonance method with a constant current circuit (i.e., constant velocity) can determine the coupling parameters more precisely from a perfectly-symmetrical resonance spectrum. The general problem in both resonance methods is heat generation in the sample during the measurement. In order to separate the temperature characteristic from the non-linearity, it is recommended that the pulse method be used in parallel, even though the accuracy is not very high.

Electrodermal lability and hypertension

Thirty-nine (39) middle-aged subjects with mild to moderate hypertension (WHO stages I–II) and 35 healthy normotensive controls from a community sample participated in this psychophysiological study, the aim of which was to study whether the electrodermal lability as an indicator of increased sympathetic activity is related to hypertension. Resting blood pressure was measured by using a mercury sphygmomanometer. Electrodermal activity was recorded with a constant voltage circuit. Bipolar skin electrodes were placed on the palmar side of the middle phalanges of the index and middle fingers of both hands. Six years after the electrodermal measurements, the possible use of reimbursed antihypertensive medication was checked in both groups, and blood pressure re-measured in the control group. Multivariate analysis controlling for age, gender and body mass showed that the electrodermal lability was increased in the hypertensive as compared to the normotensive group. This supports the hypothesis that the sympathetic nervous system tonus is increased at least, in some middle-aged subjects with mild to moderate hypertension.

Analysis of resonant type constant voltage circuit with feedback

Analysis of resonant type constant voltage circuit with feedback

An inexpensive multiplexing system for recording multiple physiological responses from several subjects concurrently

A complete multiplexing system capable of transducing and recording four physiological responses concurrently from six subjects at a time is described. Skin conductance level was recorded from the nonpreferred hand with the aid of a simple constant-voltage circuit. Tempera-ture was recorded from the left and right middle fingers with thermistors. Integrated electromyographic activity was recorded from the frontalis muscle with a previously described biofeedback circuit. An electromechanical rotary switch serves as a multiplexer. Responses are converted to frequencies by voltage-to-frequency integrated circuits and recorded on a four-channel AM tape recorder. The records are subsequently transcribed by a Data General computer and InterACT circuitry programmed to count and print frequencies. Data obtained from 36 subjects as they viewed a feature-length film containing explicit violence are presented.

Stability criterion for Gunn diodes with injection-limiting cathodes

According to McCumber [1] a Gunn diode with an ohmic cathode (i.e., cathode \sigma_{c} = \delta ) is stable in a constant-voltage circuit if n_{0}L \le (n_{0}L)_{crit} \equiv 2.7 \times 10^{11} cm-2where n_{0}L is the doping-length product. We show that the same stability criterion applies to Gunn diodes with an injection-limiting cathode (\sigma_{c} \rightarrow 0) , if (n_{0}L)_{crit} is allowed to be a function of \sigma_{c}L . The value of (n_{0}L)_{crit} increases by 30 percent if (\sigma_{c}L) varies from infinity (ohmic cathode) to zero (injection-limiting cathode). If a cathode with negative differential conductivity is realizable, it may be possible to extend the (n_{0}L) region of stable operation of Gunn diodes drastically.

Method for recording foot pad impedance in freely moving mice

The foot pad impedance of a freely moving mouse was measured in a shock runway. Foot pad impedance measurement consisted of a constant current circuit for measuring impedance when the current was subthreshold and a constant voltage circuit for measuring impedance when the current was at an aversive level. Both of these circuits are diagrammed and discussed. Foot pad impedance records obtained by this method are shown.

A Pirani Gauge Improved on Filament Material

Pirani gauge with a tungsten filament has been widely used. The unstable sensitivity due to contamination of a tungsten filament, however, is one serious shortcoming of it.Therefore, in order to eliminate this defect, a Pirani gauge with of coiled filament platinum clad molybdenum has been developed and put to the test, and it has been clearly proved to be stable enough for using by constant voltage circuit in oxygen and satisfactory from both the results of observation of the filament contamination with an electron microscope, and test of the strength with a simple mechanical tester.

The design of solenoid electromagnets

The design of the electrical portion of a solenoid-operated relay may be divided into two main sections, namely, a consideration of the characteristics of the circuit for the magnetic lines of force and the most efficient solenoid winding to produce the forces suited to the working conditions. The forces for a simple plunger type of relay and the increased forces obtained by (1) introducing a short length of iron into the core of the solenoid and (2) providing a complete iron return path for the flux exterior to the winding are treated in detail. The limit for a solenoid winding is the heat rating and a number of formulae are derived to show the relations between the various factors involved, such as the ampere turns, energy losses, resistance, etc., in order that, knowing the conditions and the required performance, an efficient winding may be used. The formulae are applied in two particular cases, namely, (a) a constant voltage circuit and (b) a constant current circuit, to show the effect of modifying the relative dimensions of the diameter and length of the solenoid. The main results arrived at in the design of the magnetic circuit and the winding, in order to obtain an efficient relay, are applied to the particular practical example of improvements to the original design of the Barr type of heavy-current relay. The modifications introduced are treated in detail and the improvements are shown to be very substantial, both in a reduction of the cost of construction of the relay and in a greater rapidity of action when the relay is in operation.