4555 results about "Open-circuit voltage" patented technology

An expert system manages a power grid wherein charging stations are connected to the power grid, with electric vehicles connected to the charging stations, whereby the expert system selectively backfills power from connected electric vehicles to the power grid through a grid tie inverter (if present) within the charging stations. In more traditional usage, the expert system allows for electric vehicle charging, coupled with user preferences as to charge time, charge cost, and charging station capabilities, without exceeding the power grid capacity at any point. A robust yet accurate state of charge (SOC) calculation method is also presented, whereby initially an open circuit voltage (OCV) based on sampled battery voltages and currents is calculated, and then the SOC is obtained based on a mapping between a previously measured reference OCV (ROCV) and SOC. The OCV-SOC calculation method accommodates likely any battery type with any current profile.

A state of charge indicator includes a current sensing circuit for sensing and converting charge or discharge current of a battery into a bipolar voltage. A counter circuit counts battery charge. A charge / discharge circuit is operatively connected to the current sensing and counter circuits and detects the voltage polarity from the current sensing circuit and sets the counter circuit to a count mode with an up or down count for a respective charge or discharge. A reset circuit is operative with the current sensing circuit, counter circuit and charge / discharge circuit for resetting the counter circuit to an actual state-of-charge of the battery after delay when the battery is idle representative of a battery open circuit voltage.

An expert system manages a power grid wherein charging stations are connected to the power grid, with electric vehicles connected to the charging stations, whereby the expert system selectively backfills power from connected electric vehicles to the power grid through a grid tie inverter (if present) within the charging stations. In more traditional usage, the expert system allows for electric vehicle charging, coupled with user preferences as to charge time, charge cost, and charging station capabilities, without exceeding the power grid capacity at any point. A robust yet accurate state of charge (SOC) calculation method is also presented, whereby initially an open circuit voltage (OCV) based on sampled battery voltages and currents is calculated, and then the SOC is obtained based on a mapping between a previously measured reference OCV (ROCV) and SOC. The OCV-SOC calculation method accommodates likely any battery type with any current profile.

A solar cell regulator in a nanosatellite includes a pulse width modulated DC-DC boost converter and a peak power tracking controller for converting solar cell power to bus power for charging of system batteries and powering loads while the controller controls the pulse width modulation operation of the converter for sensing solar cell currents and voltages along a power characteristic curve of the solar cell for peak power tracking, for determining any power data point, including a peak power point, an open circuit voltage point, and a short circuit current point along the power characteristic curve of the solar cell, and for communicating the power data to a satellite processor for monitoring the performance of the solar cell during operational use of the satellite.

A method and apparatus for aggregating power from multiple sources generates a single direct current regulated voltage. The apparatus comprises a plurality of slave voltage converters and a master pulse width modulator circuit. Providing a plurality of direct current power sources, current is drawn through a plurality of lines connected to the plurality of direct current power sources. An open circuit voltage for each direct current power source is unknown. Each line of the plurality of lines has a line resistance. The line resistance of at least some of the plurality of lines may be unknown. The line resistance of at least some of the plurality of lines is large. The single direct current regulated voltage is generated from the drawn current.

The present invention provides a thin film amorphous silicon-crystalline silicon back heterojunction and back surface field device configuration for a heterojunction solar cell. The configuration is attained by the formation of heterojunctions on the back surface of crystalline silicon at low temperatures. Low temperature fabrication allows for the application of low resolution lithography and / or shadow masking processes to produce the structures. The heterojunctions and interface passivation can be formed through a variety of material compositions and deposition processes, including appropriate surface restructing techniques. The configuration achieves separation of optimization requirements for light absorption and carrier generation at the front surface on which the light is incident, and in the bulk, and charge carrier collection at the back of the device. The shadowing losses are eliminated by positioning the electrical contacts at the back thereby removing them from the path of the incident light. Back contacts need optimization only for maximum charge carrier collection without bothering about shading losses. A range of elements / alloys may be used to effect band-bending. All of the above features result in a very high efficiency solar cell. The open circuit voltage of the back heterojunction device is higher than that of an all-crystalline device. The solar cell configurations are equally amenable to crystalline silicon wafer absorber as well as thin silicon layers formed by using a variety of fabrication processes. The configurations can be used for radiovoltaic and electron-voltaic energy conversion devices.

A power source apparatus mounted to a vehicle is equipped with a lead-acid battery and a lithium battery. An open circuit voltage and an internal resistance of each of the batteries are determined to satisfy the following conditions (a1), (a2), and (a3): (a1) In the use range of SOC of the lead-acid battery and the use range of SOC of the lithium battery, there is an equal voltage point Vds at which the open circuit voltage V0 (Pb) of the lead-acid battery becomes equal to the open circuit voltage V0 (Li) of the lithium battery; (a2) The relationship of V0 (Li)>V0 (Pb) is satisfied in the upper limit side of the use range of SOC of the battery; and (a3) A terminal voltage Vc (Li) of the lithium battery is not more than a set voltage Vreg of a regulator when a maximum current flows in the lithium battery.

The remaining run-time (t_rem) of a battery is determined independently of the condition of the battery and the amount of load on the battery by obtaining the value of a present total zero-current capacity (Qmax) of the battery based on relaxed-battery OCV values measured just before and just after a charging or discharging cycle. A current through the battery is integrated to determine a transfer of charge (Q) from the battery, and a value of total run-time (t_total) that would be required to reduce the open circuit voltage of the battery to a predetermined lower limit (Vmin) is determined. The remaining run-time (t_rem) is determined by subtracting the duration of the integrating from the total run-time (t_total).

The invention discloses a method for estimating battery health of an electric automobile, which relates to methods for estimating battery health according to voltage characteristics of a battery charging end. The method solves the defect that battery parameters, such as impedance, internal resistance and the like, need to be calculated while estimating battery health in the prior art. The method is used for estimating battery health. The method comprises the following steps of: emptying a new battery to be detected, and fully charging the new battery to be detected, and in the fully charging process, recording a voltage-time curve and a charge capacity-time curve of charging of the new battery to be detected; calculating actually usable capacity Qnew of the new battery to be detected; setting a threshold of V / dQ; calculating the charged capacity of the new battery to be detected from the time when the threshold of dV / dQ is realized to the time when the battery is fully charged during the charging process; building a relation curve of the open-circuit voltage and SOC (State Of Charge) of the new battery to be detected; estimating a SOCocv, then, calculating theoretically usable capacity Qtest-full of the attenuated battery; and obtaining the health of the battery to be detected according to the attenuated theoretically usable capacity QoId and the actually usable capacity Qnew of the battery.

The invention provides a combined estimation method for lithium ion battery state of charge, state of health and state of function. The combined estimation method comprises the steps that the state of he---alth of a battery is estimated online: open circuit voltage and internal resistance are identified online by adopting a recursive least square method with a forgetting factor, the state of charge is indirectly acquired according to a pre-established OCV-SOC corresponding relation, and then the size of battery capacity is estimated according to cumulative charge and discharge electric charge between two SOC points; the state of charge of the battery is estimated online: the state of charge of the battery is estimated by adopting the Kalman filter algorithm based on a two-order RC equivalent circuit model, and the battery capacity parameter in the Kalman filter algorithm is updated according to the estimation result of battery capacity; and the state of function of the battery is estimated online: the maximum chargeable and dischargeable current is calculated based on the voltage limit and the current limit of the battery according to internal resistance obtained by online identification, and then the maximum chargeable and dischargeable function can be obtained through further calculation.

A method for charging a battery, such as a lithium based battery, which applies different charge pulses and discharge pulses to the battery, takes voltage measurements during those charge pulses, discharge pulses, and rest periods between the charge pulses and discharge pulses, and determines whether to terminate or to continue charging the battery. The full sequence of charge pulses, discharge pulses, and rest periods, includes a plurality of charge pulses (1), separated by rest periods (2) and followed by a rest period (3). This is then followed by a plurality of discharge pulses (4), separated by rest periods (5) and followed by a rest period (6). This is then followed by a plurality of extended charge pulses (7), separated by rest periods (8) and followed by a rest period (9). Then another discharge pulse (10) is applied, followed by a rest period (11). This is followed by a plurality of alternating charge pulses (13) and discharge pulses (12), separated by rest periods (13, 15) and followed by a rest period (16). Then another plurality of discharge pulses (17) is applied, separated by rest periods (18) and followed by a rest period (19). Open circuit voltage measurements taken during the rest periods, loaded circuit voltage measurements taken during the discharge pulses, and charge pulse voltage measurements taken during the charge pulses, are used to determine whether to continue or to terminate the charging of the battery.

A power inverter system includes a DC to AC inverter configured to convert DC voltage from a DC power source to AC voltage. A DC link couples the DC power source and the inverter. An inverter pre-charger operates to pre-charge the inverter to achieve a desired DC link voltage prior to connecting the power inverter system to an AC power grid. A phased lock loop synchronizes the pre-charged inverter to the AC power grid prior to connecting the power inverter system to the AC power grid. The pre-charged inverter regulates the DC link voltage to about the minimum voltage level that allows control of AC grid currents via the inverter subsequent to connecting the power inverter system to the AC grid. The inverter operates in a maximum power point tracking control mode only subsequent to a first voltage transient caused by connecting the DC power source to energize the power inverter system.

A battery management system (BMS) manages a battery for a hybrid vehicle including an engine control unit and a motor generator controlled by the engine control unit and connected to a battery including at least one battery pack, each pack including a plurality of battery cells. The BMS includes a sensor and an MCU unit. The sensor detects temperature, current, and open circuit voltage (OCV) of the battery. The MCU receives the detected temperature, current, and OCV, calculates a key-off time period which is a period between a time point when a battery key-on state ends and a time point when a subsequent battery key-on state begins, calculates an OCV error range corresponding to an SOC error range detected at the key-off time point, and infers an initial SOC of the battery.

A method and apparatus is provided for determining how a vehicle battery would perform when used to start a vehicle. A discharge voltage / current of the battery is predicted as a function of a battery dynamic parameter, an open circuit voltage of the battery, a battery temperature and a fixed current / voltage value at which the battery is to be discharged. This discharge voltage / current value is compared to a minimum starting voltage / current required to start the vehicle in which the battery is employed and an output indicative of a starting capability of the battery is provided.

An alkali metal, solid cathode, nonaqueous electrochemical cell capable of delivering high current pulses, rapidly recovering its open circuit voltage and having high current capacity, is described. The stated benefits are realized by the addition of at least one nitrate additive to an electrolyte comprising an alkali metal salt dissolved in a mixture of a low viscosity solvent and a high permittivity solvent. A preferred solvent mixture includes propylene carbonate, dimethoxyethane and an alkali metal nitrate, alkaline earth metal nitrate and / or an organic alkyl nitrate additive.

The invention discloses a method for predicting the left capacity and the health status of a storage battery. According to the invention, predicting the left capacity of the battery based on an ampere hour integration method and an open-circuit voltage method is realized, an adjustment is carried out based on discharge currents and ambient temperature, a self correction is carried out in a process of continuous driving and influences from cell agedness on electric capacity prediction are corrected. Based on the working characteristic of a vehicle cell, a cell failure determination mode based on a combination of open-circuit voltage and ampere hour integration is put forward and the trouble of carrying out a check discharge test towards the cell is avoided. Experiments show that in the case of vehicle power storage battery which is not at a float status in a long term, the capacity obtained from the method has a high reliability. The invention is directed to the social background that motor-assisted bicycles are frequently used at present while most users know little about the cell status and has great application significances.

A battery capacity measuring device in accordance with the present invention has a fully-charged state detector (80e), a detected current integrator (80a), a divider (80b), and a corrector (80c) incorporated in a microcomputer (80). The fully-charged state detector detects that a battery is fully charged. The detected current integrator integrates current values that are detected by a current sensor during a period from the instant the battery is fully charged to the instant it is fully charged next. The divider divides the integrated value of detected current values by the length of the period. The corrector corrects a detected current using the quotient provided by the divider as an offset. Furthermore, a remaining battery capacity calculating system comprises a voltage detecting unit (50), a current detecting unit (40), an index calculating unit, a control unit, and a calculating unit. The voltage detecting unit detects the voltage at the terminals of a battery. The current detecting unit detects a current flowing through the battery. The index calculating unit calculates the index of polarization in the battery according to the detected current. The control unit controls the output voltage of an alternator so that the index of polarization will remain within a predetermined range which permits limitation of the effect of polarization on the charged state of the battery. When the index of polarization remains within the predetermined range, the calculating unit calculates the remaining capacity of the battery according to the terminal voltage of the battery, that is, the open-circuit voltage of the battery.

A method and apparatus for simulating a battery tester with a fixed resistance load, such as a widely used Japanese load tester that rates the strength of Japanese batteries that are categorized under the Japanese Industrial Standard (JIS), are provided. This invention simulates such a device without invoking large current loads, yields familiar results, utilizes an existing database and provides more conclusive testing. The method includes measuring an open circuit voltage (OCV), temperature and a dynamic parameter of the battery. A load voltage of the battery is estimated as a function of the measured battery dynamic parameter, the OCV, the load resistance value of the load tester and the battery temperature. A bounceback voltage (BBV) of the battery is then predicted. The BBV, the load voltage and the battery temperature are utilized to rate the strength of the battery.

A method and apparatus for testing a storage battery is provided that generates a temperature at which the battery will fail to meet performance criteria. The use of a temperature-based system to rate battery performance provides a clearer understanding to those not skilled in the art of battery testing. The critical failure temperature is obtained using the battery parameters of open circuit voltage, temperature and a dynamic parameter such as conductance or resistance.

A system for actively controlling the charging profile of a battery uses a software-based alternator control unit to control the charging voltage. The system optimizes battery and alternator life. The system, on a dynamic basis, uses battery open-circuit voltage (OCV) to estimate battery state-of-charge (SOC). Also, the charging current of the battery is periodically estimated; this, after processing, provides an estimated SOC of the battery.

Provided is a secondary battery in which high energy density can be obtained and charging / discharging cycle characteristic can be improved. A positive electrode (13) and a negative electrode (15) are stacked with a separator (16) interposed therebetween, and are enclosed inside an exterior can (11) to which an electrolyte is injected. The negative electrode (15) contains a negative electrode material capable of occluding / releasing lithium in an ionic state. Thereby, lithium metal precipitates in the negative electrode (15) in a state where the open circuit voltage is lower than the overcharge voltage. In other words, lithium is occluded in an ionic state in a negative electrode material capable of occluding / releasing lithium in the beginning of charging, and then lithium metal precipitates on the surface of the negative electrode material thereafter during charging. The amount of precipitation of lithium metal is preferable to be from 0.05 to 3.0 times, both inclusive, the ability of charging capacity of the negative electrode material capable of occluding / releasing lithium. Thereby, a high energy density and an excellent cycle characteristic can be obtained.

A system and method for calibrating a sensor of a characteristic monitoring system in real time utilizes a self-calibration module for periodic determination of, and compensation for, the IR drop across unwanted resistances in a cell. A current-interrupt switch is used to open the self-calibration module circuit and either measure the IR drop using a high-frequency (MHz) ADC module, or estimate it through linear regression of acquired samples of the voltage across the sensor's working and reference electrodes (Vmeasured) over time. The IR drop is then subtracted from the closed-circuit value of Vmeasured to calculate the overpotential that exists in the cell (Vimportant). Vimportant may be further optimized by subtracting the value of the open-circuit voltage (Voc) across the sensor's working and reference electrodes. The values of Vmeasured and Vimportant are then controlled by respective first and second control units to compensate for the IR drop.

An apparatus estimates SOH of a battery based on a battery voltage variation pattern. A data storing unit obtains and stores battery voltage, current and temperature data from sensors, at each SOH estimation. A first SOC estimating unit estimates first SOC by current integration using the battery current data. A second SOC estimating unit estimates open-circuit voltage from the voltage variation pattern, and calculates and stores second SOC corresponding to the open-circuit voltage and temperature using correlations between the open-circuit voltage / temperature and SOC. A weighted mean convergence calculating unit calculates and stores convergence value for weighted mean value of ratio of the second SOC variation to the first SOC variation. A SOH estimating unit estimates capacity corresponding to the weighted mean convergence value using correlation between the weighted mean convergence value and the capacity, estimates relative ratio of the estimated capacity to an initial capacity, and stores it as SOH.

An alkali metal, solid cathode, nonaqueous electrochemical cell capable of delivering high current pulses, rapidly recovering its open circuit voltage and having high current capacity, is described. The stated benefits are realized by the addition of at least one phosphonate additive to an electrolyte comprising an alkali metal salt dissolved in a mixture of a low viscosity solvent and a high permittivity solvent. A preferred solvent mixture includes propylene carbonate, dimethoxyethane and an alkyl phosphonate additive.

A method of determining the impedance, inductance, and resistance of the network connecting an electrical power supply to an electric arc welding station including an electrode and a workpiece, wherein the method-comprises: shorting the electrode to the workpiece; creating at least one waveform including a first state operating the power supply at constant current of a selected value and a second state operating the power supply at a low value of current or open circuit voltage whereby the current decays from the selected value along a decay path indicative of di / dt; obtaining the average current Iavg and average resistance Ravg during the first state; selecting a portion of the decay path; sampling the instantaneous current for a number of times on the path during the second state to read the rate of the decay; and, using the average current and the average resistance with the rate of decay to obtain the inductance of the network.

A method of operating a lithium-ion cell comprising (a) a cathode comprising a carbon or graphitic material having a surface area to capture and store lithium thereon; (b) an anode comprising an anode active material; (c) a porous separator disposed between the two electrodes; (d) an electrolyte in ionic contact with the two electrodes; and (e) a lithium source disposed in at least one of the two electrodes to obtain an open circuit voltage (OCV) from 0.5 volts to 2.8 volts when the cell is made; wherein the method comprises: (A) electrochemically forming the cell from the OCV to either a first lower voltage limit (LVL) or a first upper voltage limit (UVL), wherein the first LVL is no lower than 0.1 volts and the first UVL is no higher than 4.6 volts; and (B) cycling the cell between a second LVL and a second UVL.

A solar array system includes a plurality of power-generator modules, each power-generator module having an identical form factor and comprising a plurality of photovoltaic cells wired for power generation. The system also includes at least one sensor module having a substantially identical appearance and form factor as the power-generator modules and comprising a like plurality of photovoltaic cells. The operational state of the system is monitored by an array performance monitor, which measures signals sent from the various modules. At least one photovoltaic cell in the sensor module delivers a short-circuit current signal to the array performance monitor and at least one photovoltaic cell in the sensor module delivers an open-circuit voltage signal to the array performance monitor. These signals are used to calculate a theoretical power output of the array system, which is compared to the actual power output.

The invention discloses a lithium ion battery internal temperature monitoring method. The monitoring method includes the following steps that a charge-discharge tester is used for carrying out charge-discharge tests on a lithium ion battery on different environment conditions to obtain a battery surface temperature change curve; related parameters such as battery internal resistance and an open-circuit voltage temperature coefficient are tested, and a lithium ion battery electric heating coupling model based on a variable heat production rate is set up; the temperature rise change of the discharge process of the battery is simulated to obtain a temperature change simulation curve; the experiment test temperature change curve and the simulation curve are analyzed and compared to optimize and verify the electric heating coupling model; the influence between the battery internal temperature and the battery surface temperature as well as the influence between the discharge currents and the discharge depth are analyzed, and a lithium ion battery internal temperature model is constructed; the battery internal temperature is monitored in real time according to the model. The lithium ion battery internal temperature monitoring method is simple and easy to implement, small in estimation error and capable of well meeting the requirement for monitoring the battery internal temperature in real time.

An apparatus for estimating state-of-health (SOH) of a battery is disclosed, which comprises: a measurement unit, for measuring a working current, a working voltage and a working temperature of the battery; an observer unit, for observing voltages at an output end and RC parallel circuits of the battery; an adaptive algorithm unit, for updating parameters of the battery; an internal voltage estimation unit, for estimating the internal voltages of the RC parallel circuits; an open-circuit voltage (OCV) estimation unit, for estimating static open-circuit voltage of the battery; a SOH estimation unit, for estimating an SOH of the battery; and a state-of-charge (SOC) estimation unit, for estimating a SOC of the battery.

The invention is a charge state evaluation method and system of a power lithium ion battery. According to the method, step one is to establish a circuit model of an equivalent battery. Charging and discharging and standing experiments are performed on the battery, and timing sampling is performed so that a voltage time curve is obtained. Model parameters are identified via a formula so that a non-linear relation between an open-circuit voltage OCV and an SoC is obtained. Step two is to obtain an optical estimation value of the SoC by matrixes of state prediction, prediction error variance, filtering gain, state estimation, estimation error variance, etc., according to Kalman algorithm. According to the system, an analog / digital converter, a program storage device, a programmable storage device, a timer and a displayer are respectively connected with a microprocessor. A current sensor and a voltage sensor are respectively connected in a circuit formed by connecting the battery to be tested and a load, and outputs of the current sensor and the voltage sensor are accessed into the analog / digital converter. The programmable storage device stores battery model parameters obtained by the experiments. The program storage device stores estimation program of the method. Estimation precision of the SoC can reach 1%, and the charge state evaluation method and system is more stable; besides, the system provides estimation values of the SoC in real time.