Method and Apparatus for InSitu Real Time Characterization of Energy Storage and Energy Conversion Devices
Opening the door to real time battery health assessment
Idaho National Laboratory
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Technology Fact Sheet (1,352 KB)
Impedance Measurement Box (IMB) provides valuable, real time data about battery state of health.
DescriptionINL has developed a method and apparatus for determining an impedance of an energyoutput device using a random noise stimulus applied to the energyoutput device. A random noise signal is generated and converted to a random noise stimulus as a current source correlated to the random noise signal. A biasreduced response of the energyoutput device to the random noise stimulus is generated by comparing a voltage at the energyoutput device terminal to an average voltage signal. The random noise stimulus and biasreduced response may be periodically sampled to generate a timevarying current stimulus and a timevarying voltage response, which may be correlated to generate an autocorrelated stimulus, an autocorrelated response, and a cross correlated response. Finally, the autocorrelated stimulus, the autocorrelated response, and the cross correlated response may be combined to determine at least one of impedance amplitude, impedance phase, and complex impedance.
BenefitsImpedance in energy storage devices (e.g. batteries) can be measured real time in situ or in a laboratory.
Impedance spectra can be used to assess battery health metrics such as state of charge, capacity, available power and remaining useful life.
Applications and IndustriesElectrochemical energy storage devices. Battery test equipment, Auto industry, Utility industry, Military.
Patents and Patent ApplicationsID Number 
Title and Abstract  Primary Lab 
Date 

Patent 7,675,293 
Method and apparatus for insitu characterization of energy storage and energy conversion devices
Disclosed are methods and apparatuses for determining an impedance of an energyoutput device using a random noise stimulus applied to the energyoutput device. A random noise signal is generated and converted to a random noise stimulus as a current source correlated to the random noise signal. A biasreduced response of the energyoutput device to the random noise stimulus is generated by comparing a voltage at the energyoutput device terminal to an average voltage signal. The random noise stimulus and biasreduced response may be periodically sampled to generate a timevarying current stimulus and a timevarying voltage response, which may be correlated to generate an autocorrelated stimulus, an autocorrelated response, and a crosscorrelated response. Finally, the autocorrelated stimulus, the autocorrelated response, and the crosscorrelated response may be combined to determine at least one of impedance amplitude, impedance phase, and complex impedance. 
Idaho National Laboratory  03/09/2010
Issued 
Patent 7,395,163 
Method of detecting system function by measuring frequency response
Real time battery impedance spectrum is acquired using one time record, Compensated Synchronous Detection (CSD). This parallel method enables battery diagnostics. The excitation current to a test battery is a sum of equal amplitude sin waves of a few frequencies spread over range of interest. The time profile of this signal has duration that is a few periods of the lowest frequency. The voltage response of the battery, average deleted, is the impedance of the battery in the time domain. Since the excitation frequencies are known, synchronous detection processes the time record and each component, both magnitude and phase, is obtained. For compensation, the components, except the one of interest, are reassembled in the time domain. The resulting signal is subtracted from the original signal and the component of interest is synchronously detected. This process is repeated for each component. 
07/01/2008
Issued 

Patent 8,150,643 
Method of detecting system function by measuring frequency response
Realtime battery impedance spectrum is acquired using a onetime record. Fast Summation Transformation (FST) is a parallel method of acquiring a realtime battery impedance spectrum using a onetime record that enables battery diagnostics. An excitation current to a battery is a sum of equal amplitude sine waves of frequencies that are octave harmonics spread over a range of interest. A sample frequency is also octave and harmonically related to all frequencies in the sum. The time profile of this signal has a duration that is a few periods of the lowest frequency. The voltage response of the battery, average deleted, is the impedance of the battery in the time domain. Since the excitation frequencies are known and octave and harmonically related, a simple algorithm, FST, processes the time record by rectifying relative to the sine and cosine of each frequency. Another algorithm yields real and imaginary components for each frequency. 
Idaho National Laboratory  04/03/2012
Issued 
Patent 8,352,204 
Method of detecting system function by measuring frequency response
Methods of rapidly measuring an impedance spectrum of an energy storage device insitu over a limited number of logarithmically distributed frequencies are described. An energy storage device is excited with a known input signal, and a response is measured to ascertain the impedance spectrum. An excitation signal is a limited time duration sumofsines consisting of a select number of frequencies. In one embodiment, magnitude and phase of each frequency of interest within the sumofsines is identified when the selected frequencies and sample rate are logarithmic integer steps greater than two. This technique requires a measurement with a duration of one period of the lowest frequency. In another embodiment, where selected frequencies are distributed in octave steps, the impedance spectrum can be determined using a captured time record that is reduced to a halfperiod of the lowest frequency. 
Idaho National Laboratory  01/08/2013
Issued 
Patent 8,762,109 
Crosstalk compensation in analysis of energy storage devices
Estimating impedance of energy storage devices includes generating input signals at various frequencies with a frequency step factor therebetween. An excitation time record (ETR) is generated to include a summation of the input signals and a deviation matrix of coefficients is generated relative to the excitation time record to determine crosstalk between the input signals. An energy storage device is stimulated with the ETR and simultaneously a response time record (RTR) is captured that is indicative of a response of the energy storage device to the ETR. The deviation matrix is applied to the RTR to determine an inphase component and a quadrature component of an impedance of the energy storage device at each of the different frequencies with the crosstalk between the input signals substantially removed. This approach enables rapid impedance spectra measurements that can be completed within one period of the lowest frequency or less. 
06/24/2014
Issued 

Patent 8,868,363 
Method of estimating pulse response using an impedance spectrum
Electrochemical Impedance Spectrum data are used to predict pulse performance of an energy storage device. The impedance spectrum may be obtained insitu. A simulation waveform includes a pulse wave with a period greater than or equal to the lowest frequency used in the impedance measurement. Fourier series coefficients of the pulse train can be obtained. The number of harmonic constituents in the Fourier series are selected so as to appropriately resolve the response, but the maximum frequency should be less than or equal to the highest frequency used in the impedance measurement. Using a current pulse as an example, the Fourier coefficients of the pulse are multiplied by the impedance spectrum at corresponding frequencies to obtain Fourier coefficients of the voltage response to the desired pulse. The Fourier coefficients of the response are then summed and reassembled to obtain the overall time domain estimate of the voltage using the Fourier series analysis. 
10/21/2014
Issued 

Patent 9,244,130 
Method, system and computerreadable media for measuring impedance of an energy storage device
Realtime battery impedance spectrum is acquired using a onetime record. Fast Summation Transformation (FST) is a parallel method of acquiring a realtime battery impedance spectrum using a onetime record that enables battery diagnostics. An excitation current to a battery is a sum of equal amplitude sine waves of frequencies that are octave harmonics spread over a range of interest. A sample frequency is also octave and harmonically related to all frequencies in the sum. A time profile of this sampled signal has a duration that is a few periods of the lowest frequency. A voltage response of the battery, average deleted, is an impedance of the battery in a time domain. Since the excitation frequencies are known and octave and harmonically related, a simple algorithm, FST, processes the time profile by rectifying relative to sine and cosine of each frequency. Another algorithm yields real and imaginary components for each frequency. 
Idaho National Laboratory  01/26/2016
Issued 
Application 20140358462 
APPARATUSES AND METHODS FOR TESTING ELECTROCHEMICAL CELLS BY MEASURING FREQUENCY RESPONSE
Realtime battery impedance spectra are acquired by stimulating a battery or battery system with a signal generated as a sum of sine signals at related frequencies. An impedance measurement device can be used to interface between the battery system and a host computer for generating the signals. The impedance measurement device may be calibrated to adapt the response signal to more closely match other impedance measurement techniques. The impedance measurement device may be adapted to operate at midrange voltages of about 50 volts and highrange voltages up to about 300 volts. 
Idaho National Laboratory  06/04/2014
Filed 
Technology ID  Development Stage  Availability  Published  Last Updated 

B541, BA395, BA396, BA396C1, BA421, BA559, BA480, BA487, BA706, BA822, BA831  Exclusively Licensed  Prototype systems have been built and are in use.  Licensed  04/14/2011  02/14/2017 