Showing papers on "State of charge published in 2002"

Fuzzy logic control for parallel hybrid vehicles

Abstract: In this paper, a fuzzy logic controller is developed for hybrid vehicles with parallel configuration. Using the driver command, the state of charge of the energy storage, and the motor/generator speed, a set of rules have been developed, in a fuzzy controller, to effectively determine the split between the two powerplants: electric motor and internal combustion engine. The underlying theme of the fuzzy rules is to optimize the operational efficiency of all components, considered as one system. Simulation results were used to assess the performance of the controller. A forward-looking hybrid vehicle model was used for implementation and simulation of the controller. Potential fuel economy improvement is shown by using fuzzy logic, relative to other controllers, which maximize only the efficiency of the engine.

Battery management unit, system and method

Abstract: A battery management unit and system for managing the state of charge of cells or batteries (B1-B10). Each battery management unit (1) measures cell or battery terminal voltage and provides this information to a central controller (3) via a communication medium (2). Each battery management unit (1) monitors a plurality of batteries (B1-B10) and can selectively charge a selected battery (B1-B10) via a charger (7) and switch circuit (8, 17) or can selectively discharge a selected battery (B1-B10) via a load (10) and switch circuit (8, 17) under the control of a controller (6). The controller (6) may control charging and discharging in accordance with measurements from voltage sensors (15a-j) or may convey information from a voltge sensors (15a-15j) to the central controller (3) and receive charging and discharging commands from the central controller (3). Charging and discharging is controlled to maintain all batteries within a desired state of charge ranged. The central controller (3) may selectively connect a main charger (20) or generator (21) to a bank of batteries associated with a battery management unit (1).

State of charge prediction method and apparatus for a battery

Abstract: A method of determining the state of a battery including the steps of generating a state vector that describes the state of the battery, predicting a response for the state vector, measuring a response of the battery, and correcting the state vector based on the differences between the predicted response and a measured response to determine the state of the battery.

Method for controlling the operating characteristics of a hybrid electric vehicle

Abstract: A control method for operating internal combustion engine electric hybrid vehicles with smaller battery packs, particularly in configurations where an electric motor (E/M) or electric motor/generator (E/MG), a battery, and associated controls are inserted between the engine and a continuously variable or automatic transmission. The interaction between the combustion engine and battery operated electric motor is controlled by taking energy into the batteries only if it is more efficient than throttling the engine and operating the engine at a lower efficiency. Additionally, the batteries are charged to a certain state or the batteries are maintained at a particular state of charge. A goal of the invention is to obtain the best possible fuel economy while maintaining good driveability.

State of charge algorithm for lead-acid battery in a hybrid electric vehicle

Abstract: A method and apparatus for determining the state of charge of a lead-acid battery. The present invention includes steps to determine a current-based state of charge while accounting for such factors as current, temperature, charge efficiency, parasitic losses and self-discharge. The present invention is capable of measuring and/or calculating the open circuit voltage during and after operation to determine a voltage-based state of charge while compensating the open circuit voltage for its transient behavior and accounting for the voltage shift caused by charge events. The correlation of the open circuit voltage to the state of charge is dependent on the battery's mode of operation. The present invention is adaptive to battery aging by updating the battery resistance, correcting coulomb errors, and accounting for capacity degradation while in operation.

State of charge method and apparatus

Abstract: A method for determining state of charge (SOC) of a battery system based upon an equivalent circuit of the battery system. A potential and resistance of the equivalent circuit are computed. The method uses a least squares regression means, and includes: providing a plurality of data points as a starting point based upon determinations including measurement or prior computation, wherein the determinations include a determination of a voltage of the battery system; weighting the plurality of data points; and computing values of the resistance and potential based upon weighted data points using recursive formulas, wherein only a state at a previous time is reflected respectively.

Method for determining state of charge of a battery by measuring its open circuit voltage

Abstract: A method (Fig. 1) for determining the state of charge (SOC) of a battery by measuring its open circuit voltage (OCV) either with the battery in a fully rested state of chemical and electrical equilibrium or an active state during a period in which the battery settles after charge or discharge is stopped. A first type algorithm (Fig. 4) is developed to correlate the OCV in a fully rested condition (OCVREST) to the state of charge at which that measurement is taken. A second type algorithm is developed that predicts a final settling OCV of a battery (OCVPRED), based on the set of parameters of OCV, rate of change of OCV, and battery case temperature, acquired during the settling period of a battery not at rest. To determine the SOC of a battery being tested that is in the fully settled state the measured OCVREST is applied to the first type algorithm (Fig. 4). To determine the SOC of a battery that has not fully settled, the data of the OCV, rate of change of OCV and battery temperature is applied to a second type algorithm to determine OCVPRED and the OCVPRED value is used in the first type algorithm to determine SOC.

A new estimation method of state of charge using terminal voltage and internal resistance for lead acid battery

Abstract: The accurate state of charge (SOC) is required for the battery for electric vehicles. Various estimation methods for the SOC of the lead acid battery have been proposed. However, any method cannot accurately predict the residual capacity. A new estimation method of the SOC on the lead acid battery is proposed. This method is based on the terminal voltage and the internal resistance of the battery. This proposed equation can decrease the estimation error for the little SOC region. We conducted discharge experiments for the lead acid battery and compared the former method with the proposed new method.

Method for determining the performance of a storage battery

Abstract: A method for determining performance of a storage battery including evaluating a time profile of voltage drop in the storage battery by application of a heavy current load, determining a voltage A from voltage response U(t) of the storage battery after switching on the heavy current load, determining a state value A1 from the voltage value A, battery temperature TBAT and state of charge SOC, comparing state value A1 with a preset value A1 x which depends at least on associated battery temperature (TBAT) and associated state of charge (SOC) of the storage battery, wherein the present value A1 x is calculated from comparison values A1 T which are determined from the state values A1 for previous heavy current loads applied to the storage battery, and determining performance of the storage battery from the difference between the present value A1 x and the state value A1.

Method and apparatus for testing and charging a power source

Abstract: A battery tester and charger is provided for safely and efficiently testing and charging partially charged and discharged batteries. Information about the battery to be tested is inputed by the user. A first heavy loaded is applied and the bounce back voltage is used to determine the state of charge of the battery. If the battery is chargeable then a set charge time is determined. If not, then the battery can be discarded.

Battery usage and thermal performance of the Toyota Prius and Honda Insight during chassis dynamometer testing

Abstract: This study describes the results from the National Renewable Energy Laboratory's (NREL) chassis dynamometer testing of a 2000 model year Honda Insight and 2001 model year Toyota Prius. The tests were conducted for the purpose of evaluating the battery thermal performance, assessing the impact of air conditioning on fuel economy and emissions, and providing information for NREL's Advanced Vehicle Simulator (ADVISOR). A comparative study of the battery usage and thermal performance of the battery packs used in these two vehicles during chassis dynamometer testing is presented. Specially designed charge and discharge chassis dynamometer test cycles revealed that the Insight limited battery usage to 60% of rated capacity, while the Prius limited battery usage to 40% of the rated capacity. The Prius uses substantially more pack energy over a given driving cycle but at the same time maintains the pack within a tight target state of charge (SOC) of 54% to 56%. The Insight does not appear to force the battery to a specific target SOC. The Prius battery contributes a higher percentage of the power needed for propulsion. The study also found that while both vehicles have adequate battery thermal management system for mild driving conditions, the Prius thermal management is more robust, and the Insight thermal management limits pack performance in certain conditions.

Method and apparatus for monitoring the state of the battery of a hybrid electric vehicle

Abstract: A system ( 40 ) for an automotive vehicle has a temperature sensor ( 90 ) generating a temperature signal indicative of the temperature outside the vehicle and a battery. A battery controller ( 54 ) is coupled to the temperature sensor ( 90 ) and the battery ( 64 ). The controller monitors a state of charge of the battery ( 64 ), monitors a temperature outside of the vehicle and compares the state of charge to a predetermined state of charge. The predetermined state of charge is a function of the temperature. The controller ( 54 ) generates an indicator when the state of charge reaches the predetermined state of charge.

Method for determining a maximum charge current and a maximum discharge current of a battery

Abstract: A method for determining a maximum charge current of a battery is provided which comprises: determining a steady-state charge resistance based on a current state of charge of the battery; determining a no-load charge voltage based on the current state of charge of the battery; calculating a maximum temporary charge current; and calculating a maximum charge current based on the maximum temporary charge current.

Hybrid energy storage device charge equalization system and method

Abstract: A system and method for improving the performance of a hybrid power supply apparatus comprising a power generating device, such as a fuel cell, and a primary energy storage device, such as a battery. The purpose of the invention is to provide an equalization charge to the battery from a source other than the fuel cell when the battery achieves a predetermined state of charge condition, thereby avoiding the need to operate the fuel cell in a low power output mode. When the predetermined state of charge condition is detected by a controller, the fuel cell is shut-down. In one aspect of the invention the equalization charge is provided to the battery by a secondary energy storage device, such as a plurality of capacitors or secondary batteries. The predetermined state of charge condition may be satisfied, for example, when the state of charge of the battery exceeds a predetermined threshold, such as 80 % of the battery's storage capacity, for a predetermined period of time. In some aspects of the invention, the secondary energy storage device may also be connectable to the load. Preferably the system also includes a DC/DC converter for regulating current flow between the fuel cell and the storage devices.

Fuzzy logic-based state-of-health determination of lead acid batteries

Abstract: Determining the state-of-health (SOH) of uninterruptible power supply (UPS) batteries using impedance measurements has been demonstrated by several researchers. One such approach uses single frequency impedance measurements, which may not be reliable under all circumstances. Another approach employs measurements over a wide frequency range and uses extracted equivalent circuit parameters to correlate with battery SOH. This is a computationally extensive approach and not easily incorporated into a low cost system. Over the last five years, Villanova University and US Nanocorp. have been jointly developing a patented fuzzy logic method for estimating the state-of-charge (SOC) and SOH of batteries. This methodology has proven to be both a simple and powerful means to model battery characteristics accurately and robustly. In this paper we describe how impedance measurements, combined with fuzzy logic data analysis have been used to estimate the SOH of lead acid batteries used in portable defibrillators. We also propose ways in which this approach may be extended to estimating the SOH of UPS batteries.

Control device and control method for hybrid vehicle

Abstract: A control device and control method for a hybrid vehicle is disclosed having an electric storage detecting section 13 which detects a state of charge (SOC) of an electric storage device 10. A target running efficiency calculating section 14 serves as a unit to calculate a target value of a running efficiency, indicative of a proportion of a given physical quantity, in terms of a drive power rate required for driving the vehicle such that the higher the SOC detected value, the smaller will be the target value. A target unit operating point calculating section 15 calculates a target value of a unit operating point, providing the target running efficiency, from among operating points, that cause a power rate of an internal combustion engine 1 to be utilized at the running efficiency with the maximum efficiency, of a unit 11 (the internal combustion engine 1, a clutch 2, a motor 3 and a stepped power transmission 4), and a target unit operating point actualizing section 16 operates the unit 11 at the target unit operating point.

Multiple model systems and methods for testing electrochemical systems

Abstract: A method for testing an electrochemical system includes obtaining complex impedance data for the electrochemical system at multiple frequencies; fitting the complex impedance data to two or more models of the system to obtain a set of fitted parameters; and deriving a value for a characteristic of the electrochemical system based upon parameters of the set of fitted parameters. The electrochemical system may be an electrochemical battery. The characteristic may be a state of health, state of charge, or other characteristic of a battery.

State of charge measuring apparatus for battery device

Abstract: A state of charge (SOC) measuring apparatus for a battery device is provided capable of detecting accurate state of charge based on integrating charge and discharge current. The state of charge measuring apparatus carries out data substitution for displaying and controlling state of charge depending on the upper limit SOC or lower limit SOC. The integrated SOC obtained by integrating charge and discharge currents is corrected into the corrected SOC by the incremented corrected value incremented at every data substitution time. The state of charge measuring apparatus corrects the integrated SOC at every data substitution such that the difference between the integrated SOC and the corrected SOC becomes larger, and when the integrated SOC is smaller than the upper limit SOC and larger than the lower limit SOC, the corrected SOC is displayed on the display portion as the displaying and controlling SOC.

Battery temperature management method of an electric vehicle

Abstract: A method for managing temperature of a battery of an electric vehicle is provided which comprises: determining whether a value of a state of charge of a battery is less than a predetermined value; regulating temperature of the battery such that the temperature of the battery approaches a temperature for a maximum charge power of the battery, if the value of the state of charge of the battery is less than the predetermined value; and regulating temperature of the battery such that the temperature of the battery approaches a temperature for a maximum charge amount of the battery, if the value of the state of charge of the battery is greater than the predetermined value.

State of charge calculation device and state of charge calculation method

Abstract: A state of charge calculation device includes an ammeter for detecting charge and discharge currents of a secondary battery, a state detection sensor for detecting a start time of discharge from the secondary battery to an engine, a battery electronic control unit (ECU) for calculating a state of charge of the secondary battery. The battery ECU of this state of charge calculation device calculates the state of charge of the secondary battery, based on the current and voltage detected at the time when discharge starts.

Elevator apparatus with rechargeable power supply and discharge control

Abstract: An elevator control apparatus solves a major problem with a conventional elevator control apparatus in that a state of charge of a battery is not always maintained at 100% because of the need for securing an allowance for charging regenerative electric power, causing generation of an inert material in the battery with a resultant decrease in an apparent charging capacity of the battery and a shortened life of the battery. The elevator control apparatus in accordance with the invention includes a converter, an inverter, a controller for controlling a motor based on AC power of a variable voltage and a variable frequency supplied from the inverter so as to operate an elevator; a power storage unit for storing DC power; a charge/discharge control circuit that issues a drive signal such that an amount of discharge from the power storage unit increases within a range of power that can be discharged when an elevator is driven immediately following completion of uniform charging, and a charge/discharge circuit for carrying out discharge from the power storage unit in accordance with the drive signal. This arrangement permits quick discharging while effectively using discharge electric power until a state of charge is reached wherein regenerative electric power can be charged.

A method for resetting a state of charge of a battery of a hybrid electric vehicle

Abstract: A method for resetting a state of charge of a battery for a hybrid electric vehicle comprises: determining whether a discharge current of the battery is greater than a predetermined discharge current; determining whether a minimum voltage module has changed, if the discharge current of the battery is greater than the predetermined discharge current; determining whether a theoretical discharge voltage is greater than a voltage of the minimum voltage module, if the minimum voltage module has changed; determining whether the theoretical discharge voltage remains greater than the voltage of the minimum voltage module for a predetermined period of time, if the theoretical discharge voltage is greater than the voltage of the minimum voltage module; and setting a state of charge of the battery as a very low state, if the theoretical discharge voltage remains greater than the voltage of the minimum voltage module for the predetermined period of time.

Device and method for displaying charge capacity information of smart battery

Abstract: A device and a method for displaying an exact charge capacity of a smart battery includes a portable electric device including a control unit for power management. The portable electric device includes a battery for providing a relative state of charge (RSOC), a control unit for controlling the device to display battery residual capacity information by receiving the RSOC from the battery, and a display unit for displaying the battery residual capacity information. Here, the control unit detects an output voltage of the battery, compares the detected voltage with the RSOC, and controls the device to display the battery residual capacity information in response to data corresponding to the detected voltage, when the battery is in a period of a first low battery and the detected voltage is different from the RSOC, or controls the device to display the battery residual capacity information in response to the RSOC when the battery is in a period of a second low battery lower than the first low battery. Thus, the portable electric device can display the exact battery residual capacity information by correcting a period where an error is generated between the RSOC and the detected voltage.

Control system for hybrid vehicle regulates proportion of driving power performed by electric motor whereby state of charge of battery does not fall below minimum level ensuring basic functions

Abstract: The method involves controlling the proportion of driving undertaken by the electric motor (5) according to data relating to the route and taking into account the charge in an electrical energy storage device (4). The data include information forming a basis for controlling the electric motor driving proportion, whereby the energy storage device's state of charge does not fall below a minimum level that guarantees necessary basic vehicle functions. AN Independent claim is also included for the following: a hybrid vehicle with an internal combustion engine and an electric motor supplied from an energy storage device.

Stress management of battery recharge, and method of state of charge estimation

Abstract: One or more cells are charged by measuring one or more cell parameters or changes in said cell parameters, inputting the measured cell parameter(s) or changes in cell parameters into a state of charge estimation model, obtaining a state of charge of the cell(s) from the state of charge estimation model, selecting an allowable temperature rise for the cell(s), determining a charge parameter in accordance with the state of charge of the cell(s) and in accordance with the selected allowable temperature rise for the cell(s), and supplying energy to the cell(s) in accordance with the determined charge parameter. The invention may be embodied as methods, apparatus and computer program products.

Hybrid power system for an electric vehicle

Abstract: A hybrid power system ( 10 ) for supplying power to a load ( 12 ) such as an electric vehicle is provided. The power system ( 10 ) includes an energy storage device ( 14 ) and a fuel cell system ( 16 ). When the state of charge of the energy storage device ( 14 ) is greater than or equal to a predetermined state of charge, the energy storage device ( 14 ) supplies all of the power to the load ( 12 ). When the state of charge of the energy storage device ( 14 ) falls below the predetermined state of charge, the fuel cell system ( 16 ) supplies at least a portion of the power to the load ( 12 ). In accordance with one aspect of the invention, the fuel cell system ( 16 ) then supplies all of the power to the load ( 12 ) as long as the power requirement of the load ( 12 ) does not exceed an optimal power output of the fuel cell system ( 16 ).

State-of-charge (SOC) estimation of high power Ni-MH rechargeable battery with artificial neural network

Abstract: The paper presents a three-layer feedforward backpropagation (BP) artificial neural network (ANN), whose output is battery state-of-charge (SOC), to estimate and predict SOC of high power Ni-MH rechargeable battery. Five ANN inputs are novelly selected to improve the accuracy of ANN prediction by the proposed method of correlation coefficient ranking based on correlation analysis of different variables and SOC, and they are: battery discharging current i, accumulated ampere hours Ah, battery terminal voltage v, time-average terminal voltage tav and twice time-average voltage ttav (i.e. time-average of tav). Meanwhile, six training sets are equally selected from thirteen data sets about constant current discharging (CCD) from 100 % to 0 % SOC and Levenberg-Marquardt training algorithm is selected. Comparisons between simulation and measurement verify the proposed ANN model. Especially, the ANN can satisfyingly estimate SOC of battery (pack) whose starting SOC (i.e. SOC/sub 0/) is not originally known after about ten minutes (short time compared with the whole discharging process) constant load discharging (CLD), and most of absolute values of absolute errors are not more than 5 %.

A capacitor system for a vehicle

Abstract: A capacitor system suitable for charging and discharging of a vehicle such as discharging due to starting of an engine, charging by an alternator, and recharging upon braking. The capacitor system can be a vehicle power source having several connected cells in which ion conductive materials are arranged between a pair of electrode structures with large surface area materials and an electric double layer is formed between the large surface area materials in the electrode structure and an electrolyte of the ion conductive materials. Charging and discharging are controlled for state of charge of the capacitor unit with several connected modules to be within a predetermined range. A minimum charge within the predetermined range is sufficient for the engine to start while a maximum charge within the predetermined range is within a rated voltage of the capacitor unit with several connected modules.

Battery cell balancing system

Abstract: A battery cell balancing system ( 12 ) for a battery ( 30 ) having a plurality of cells ( 32 ) is provided. The system ( 12 ) includes a power supply ( 38 ) and a plurality of transformer/rectifier circuits ( 34 ) electrically coupled to the cells ( 32 ). Preferential charging occurs for a cell with the lowest state of charge. At least one current limiting device ( 36 ) is electrically coupled to the transformer/rectifier circuits ( 34 ) and the power supply ( 38 ). The current limiting device ( 36 ) buffers a source voltage from a reflected voltage of at least one of the plurality of cells ( 32 ). A method of performing the same is also provided.