CN117148191A - Method and system for testing internal resistance of battery - Google Patents
Method and system for testing internal resistance of battery Download PDFInfo
- Publication number
- CN117148191A CN117148191A CN202311442315.7A CN202311442315A CN117148191A CN 117148191 A CN117148191 A CN 117148191A CN 202311442315 A CN202311442315 A CN 202311442315A CN 117148191 A CN117148191 A CN 117148191A
- Authority
- CN
- China
- Prior art keywords
- code value
- sampling
- voltage
- effective
- current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000012360 testing method Methods 0.000 title claims abstract description 28
- 238000005070 sampling Methods 0.000 claims abstract description 233
- 230000005284 excitation Effects 0.000 claims abstract description 32
- 238000006243 chemical reaction Methods 0.000 claims abstract description 22
- 230000003321 amplification Effects 0.000 claims description 20
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 20
- 238000002372 labelling Methods 0.000 claims description 6
- 238000005259 measurement Methods 0.000 abstract description 13
- 239000002253 acid Substances 0.000 description 6
- 238000004364 calculation method Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 238000004422 calculation algorithm Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000006978 adaptation Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000004590 computer program Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/389—Measuring internal impedance, internal conductance or related variables
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/08—Measuring resistance by measuring both voltage and current
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/385—Arrangements for measuring battery or accumulator variables
Abstract
The invention discloses a method and a system for testing internal resistance of a battery, wherein the method comprises the following steps: the signal source inputs an alternating current excitation signal with a target frequency to the target battery; the AD converter samples the voltage and the current of the target battery; the AD converter performs FFT conversion on the actual voltage code value and the actual current code value respectively to obtain a frequency domain voltage code value and a frequency domain current code value corresponding to the N sampling points; the micro control unit determines the effective voltage code value amplitude and the effective current code value amplitude of each sampling point under the target frequency; the micro control unit determines the internal resistance of the target battery according to the reference voltage of the AD converter, the resolution of the AD converter, the effective voltage code value amplitude, the effective current code value amplitude and the resistance value of the sampling resistor. The alternating current excitation signal input by the scheme is small in amplitude, the damage to the storage battery is small, the internal resistance measurement can be carried out under the working state and the non-working state of the storage battery, and the resistance measurement precision is high.
Description
Technical Field
The invention relates to the field of power electronics, in particular to a method and a system for testing internal resistance of a battery.
Background
The internal resistance of the battery is considered as a decisive parameter for judging the capacity state of the battery, and the battery state can be evaluated by testing the internal resistance of the battery.
In the prior art, a direct current discharge method is mainly adopted for testing the internal resistance of the battery. This method has the following disadvantages: firstly, when the internal resistance is measured by using a direct current discharging method, the measured storage battery needs to be separated from a working system due to the existence of a contactor in a circuit, so that the emergency function of the storage battery pack when the power supply system is powered off is lost, and potential safety hazard is brought. And secondly, because the internal resistance of the lead-acid storage battery is extremely small, when the current change at two ends of the lead-acid storage battery is extremely small, the collected voltage change is also extremely small, and noise signals in the circuit often influence the voltage collection result, so that the measurement accuracy is reduced. In order to improve the acquisition precision and reduce the noise influence, a current signal with higher amplitude needs to be applied, and a large current flows through the storage battery, so that irreversible damage is caused to the performance of the storage battery, and the service life of the storage battery is influenced. Meanwhile, excessive current can generate higher electromagnetic radiation, which affects the normal operation of surrounding circuits.
Therefore, the battery internal resistance testing method in the prior art has the problems that the tested battery is required to be separated from a working system, the measurement accuracy is low, and the performance of the battery is damaged by the applied current signal with higher amplitude.
Disclosure of Invention
The invention aims at solving at least the technical problems existing in the prior art, and therefore, a first aspect of the invention provides a battery internal resistance testing method which is applied to a battery internal resistance testing system, wherein the battery internal resistance testing system comprises a micro control unit, an AD converter, a target battery to be tested, a sampling resistor, a signal source and a programmable gain amplifier, and the method comprises the following steps:
the signal source inputs an alternating current excitation signal with a target frequency to the target battery;
the AD converter is used for counting and counting according to a preset sampling duration time and a preset sampling pointSampling the voltage and the current of the target battery at a preset sampling frequency to obtainVoltage code values and current code values of the data points; the sampling duration is K (K is more than or equal to 3) times of the alternating current excitation signal period, the number N of points is 2 to the power of m (m is an integer), and the sampling frequency is greater than or equal to N times of the target frequency;
the AD converter determines an actual voltage code value and an actual current code value corresponding to the voltage code value and the current code value according to the amplification factor of the programmable gain amplifier, and performs FFT conversion on the actual voltage code value and the actual current code value respectively to obtain a frequency domain voltage code value and a frequency domain current code value corresponding to N sampling points;
The micro control unit determines the effective voltage code value amplitude and the effective current code value amplitude of each sampling point under the target frequency according to the frequency domain voltage code value and the frequency domain current code value;
the micro control unit determines the internal resistance of the target battery according to the reference voltage of the AD converter, the resolution of the AD converter, the effective voltage code value amplitude, the effective current code value amplitude and the resistance value of the sampling resistor.
Optionally, the determining, according to the frequency domain voltage code value and the frequency domain current code value, an effective voltage code value amplitude and an effective current code value amplitude of each sampling point at the target frequency includes:
placing the frequency domain voltage code values of the N sampling points into a first array according to a sampling sequence, taking the sampling points except the first sampling point in the first array as effective sampling points, and labeling sampling point serial numbers for the effective sampling points; the sampling point sequence number is a natural number from 2;
the frequency domain current code values of the N sampling points are put into a second group according to the sampling sequence, and the sampling point serial numbers are marked for the effective sampling points;
Determining a first quotient of the sampling frequency and the target frequency;
for each sampling point in the first array, determining a second quotient of the first quotient and the sampling point sequence number;
under the condition that the second quotient is an integer, determining the product of the second quotient and the frequency domain voltage code value of the sampling point to obtain the effective voltage code value amplitude of each effective sampling point under the target frequency;
and for each sampling point in the second array, determining the product of a second quotient corresponding to the sampling point and the frequency domain current code value of the sampling point to obtain the effective current code value amplitude of each effective sampling point under the target frequency.
Optionally, after determining the second quotient of the first quotient and the sampling point sequence number, the method further includes:
inputting the first array and the second array into target software if the second quotient is not an integer;
drawing a voltage frequency domain image and a current frequency domain image corresponding to the frequency domain voltage code value and the frequency domain current code value respectively by utilizing the target software;
determining the effective voltage code value amplitude of each effective sampling point under the target frequency by utilizing the voltage frequency domain image;
And determining the effective current code value amplitude of each effective sampling point at the target frequency by using the current frequency domain image.
Optionally, the determining, according to the amplification factor of the programmable gain amplifier, an actual voltage code value and an actual current code value corresponding to the voltage code value and the current code value, and performing FFT conversion on the actual voltage code value and the actual current code value respectively includes:
respectively determining the quotient of the voltage code value and the amplification factor of the programmable gain amplifier, and obtaining an actual voltage code value and an actual current code value by the quotient of the current code value and the amplification factor;
the saidThe actual voltage code value and the actual current code value of the data point are respectively put into a third array and a fourth array according to the sampling sequence;
performing FFT conversion on the voltage code values in the third array to obtain frequency domain voltage code values corresponding to N sampling points;
and carrying out FFT conversion on the actual current code values in the fourth array to obtain frequency domain current code values corresponding to the N sampling points.
Optionally, the determining the internal resistance of the target battery according to the reference voltage of the AD converter, the resolution of the AD converter, the effective voltage code value amplitude, the effective current code value amplitude, and the resistance value of the sampling resistor includes:
Converting the effective voltage code value amplitude into an actual voltage value according to the reference voltage of the AD converter and the resolution of the AD converter;
converting the effective current code value amplitude into an actual current value according to the reference voltage of the AD converter, the resolution of the AD converter and the resistance value of the sampling resistor;
taking the quotient of the actual voltage value and the actual current value as the internal resistance value of the target battery.
The second aspect of the present invention proposes a battery internal resistance test system, which includes a micro control unit, an AD converter, a target battery to be tested, a sampling resistor, a signal source, and a programmable gain amplifier: wherein, the signal source is used for:
inputting an alternating current excitation signal with a target frequency to the target battery;
the AD converter is used for:
sampling the voltage and the current of the target battery according to a preset sampling duration, a preset sampling point number and a preset sampling frequency to obtainVoltage code values and current code values of the data points; the sampling duration is K (K is more than or equal to 3), the point number N is 2 m times (m isAn integer) the sampling frequency is greater than or equal to N times the target frequency;
Determining an actual voltage code value and an actual current code value corresponding to the voltage code value and the current code value according to the amplification factor of the programmable gain amplifier, and performing FFT (fast Fourier transform) on the actual voltage code value and the actual current code value respectively to obtain a frequency domain voltage code value and a frequency domain current code value corresponding to N sampling points;
the micro control unit is used for:
according to the frequency domain voltage code value and the frequency domain current code value, determining the effective voltage code value amplitude and the effective current code value amplitude of each sampling point under the target frequency;
and determining the internal resistance of the target battery according to the reference voltage of the AD converter, the resolution of the AD converter, the effective voltage code value amplitude, the effective current code value amplitude and the resistance value of the sampling resistor.
Optionally, the micro control unit is specifically configured to:
placing the frequency domain voltage code values of the N sampling points into a first array according to a sampling sequence, taking the sampling points except the first sampling point in the first array as effective sampling points, and labeling sampling point serial numbers for the effective sampling points; the sampling point sequence number is a natural number from 2;
The frequency domain current code values of the N sampling points are put into a second group according to the sampling sequence, and the sampling point serial numbers are marked for the effective sampling points;
determining a first quotient of the sampling frequency and the target frequency;
for each sampling point in the first array, determining a second quotient of the first quotient and the sampling point sequence number;
under the condition that the second quotient is an integer, determining the product of the second quotient and the frequency domain voltage code value of the sampling point to obtain the effective voltage code value amplitude of each effective sampling point under the target frequency;
and for each sampling point in the second array, determining the product of a second quotient corresponding to the sampling point and the frequency domain current code value of the sampling point to obtain the effective current code value amplitude of each effective sampling point under the target frequency.
Optionally, the micro control unit is further configured to:
inputting the first array and the second array into target software if the second quotient is not an integer;
drawing a voltage frequency domain image and a current frequency domain image corresponding to the frequency domain voltage code value and the frequency domain current code value respectively by utilizing the target software;
Determining the effective voltage code value amplitude of each effective sampling point under the target frequency by utilizing the voltage frequency domain image;
and determining the effective current code value amplitude of each effective sampling point at the target frequency by using the current frequency domain image.
Optionally, the AD converter is specifically configured to:
respectively determining the quotient of the voltage code value and the amplification factor of the programmable gain amplifier, and obtaining an actual voltage code value and an actual current code value by the quotient of the current code value and the amplification factor;
the saidThe actual voltage code value and the actual current code value of the data point are respectively put into a third array and a fourth array according to the sampling sequence;
performing FFT conversion on the voltage code values in the third array to obtain frequency domain voltage code values corresponding to N sampling points;
and carrying out FFT conversion on the actual current code values in the fourth array to obtain frequency domain current code values corresponding to the N sampling points.
Optionally, the micro control unit is specifically configured to:
converting the effective voltage code value amplitude into an actual voltage value according to the reference voltage of the AD converter and the resolution of the AD converter;
converting the effective current code value amplitude into an actual current value according to the reference voltage of the AD converter, the resolution of the AD converter and the resistance value of the sampling resistor;
Taking the quotient of the actual voltage value and the actual current value as the internal resistance value of the target battery.
The embodiment of the invention has the following beneficial effects:
according to the battery internal resistance testing method provided by the embodiment of the invention, the signal source inputs the alternating current excitation signal with the target frequency to the target battery; the AD converter samples the voltage and the current of the target battery according to a preset sampling duration, a preset sampling point number and a preset sampling frequency to obtainVoltage code values and current code values of the data points; the sampling duration is K (K is more than or equal to 3) times of the alternating current excitation signal period, the number N of points is 2 to the power of m (m is an integer), and the sampling frequency is greater than or equal to N times of the target frequency; the AD converter determines an actual voltage code value and an actual current code value corresponding to the voltage code value and the current code value according to the amplification factor of the programmable gain amplifier, and performs FFT conversion on the actual voltage code value and the actual current code value respectively to obtain a frequency domain voltage code value and a frequency domain current code value corresponding to N sampling points; the micro control unit determines the effective voltage code value amplitude and the effective current code value amplitude of each sampling point under the target frequency according to the frequency domain voltage code value and the frequency domain current code value; the micro control unit determines the internal resistance of the target battery according to the reference voltage of the AD converter, the resolution of the AD converter, the effective voltage code value amplitude, the effective current code value amplitude and the resistance value of the sampling resistor. The alternating current excitation signal input by the scheme is small in amplitude, small in damage to the storage battery, capable of measuring internal resistance in the working state and the non-working state of the storage battery, high in resistance measurement precision and beneficial to analysis and prediction of the battery.
Drawings
Fig. 1 is a schematic diagram of a battery internal resistance test system according to an embodiment of the present invention;
fig. 2 is a flowchart of steps of a method for testing internal resistance of a battery according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terms "first" and "second" are used below for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the embodiments of the present disclosure, unless otherwise indicated, the meaning of "a plurality" is two or more. In addition, the use of "based on" or "according to" is intended to be open and inclusive in that a process, step, calculation, or other action "based on" or "according to" one or more of the stated conditions or values may in practice be based on additional conditions or beyond the stated values.
Fig. 1 is a schematic diagram of a battery internal resistance test system according to an embodiment of the present invention.
As shown in fig. 1, the battery internal resistance test system includes a micro control unit (MCU, microcontroller Unit), an AD converter, a target battery to be tested, a sampling resistor, a signal source, and a programmable gain amplifier (Pmgramable Gain Amplifier, PGA).
The signal source, the PGA, the target battery and the sampling resistor are sequentially connected in series. The signal source is a device for providing an excitation signal, and the programmable gain amplifier is used for amplifying the amplitude of the excitation signal and changing the frequency or the phase of the signal so that the signal can meet the requirement of testing the internal resistance of the battery.
An AD converter (Analog-to-Digital Converter, ADC) is connected in parallel with the target battery, and is configured to collect voltages at both ends of the target battery and currents flowing through the target battery, and to convert the collected voltage code values and current code values into digital signals. The micro control unit is used for calculating and processing the digital signals converted by the AD converter according to a battery internal resistance test algorithm stored on the chip to obtain the internal resistance of the battery.
Fig. 2 is a flowchart of steps of a method for testing internal resistance of a battery according to an embodiment of the present invention. The method is applied to the battery internal resistance test system in fig. 1, and comprises the following steps:
Step 101, the signal source inputs an alternating current excitation signal with a target frequency to the target battery.
The signal source is a device that provides an excitation signal. The alternating current excitation signal is a voltage and current signal with direction changing and periodical change, and the magnitude, direction and frequency of the alternating current excitation signal are periodical change. The period being the inverse of the frequency, the frequency of the ac excitation signal being predetermined, as used hereinRepresenting the target frequency of the ac excitation signal, +.>Can take a value between 10Hz and 1000Hz according to the requirement. The scheme adopts an alternating current excitation signal of 100 HZ.
102, the AD converter samples the voltage and the current of the target battery according to a preset sampling duration, a preset sampling point number and a preset sampling frequency to obtainVoltage code values and current code values of the data points; the sampling duration is K (K is more than or equal to 3) times of the alternating current excitation signal period, the number N of points is m times (m is an integer) of 2, and the sampling frequency is greater than or equal to N times (N is more than or equal to 2) of the target frequency.
Sampling voltage and current by AD converter, and setting sampling duration as K (K is greater than or equal to 3) excitation signals for ensuring signal integrity And (3) a period. The sampling frequency is preset, and according to the Nyquist sampling theorem, the sampling frequency is larger than 2 times of the highest frequency of the signal, so that the complete information of the signal can be kept without distortion. Thus, the sampling frequency of the AD converterThe following should be satisfied: />，（N≥2）。
The sampling frequency of the AD converter can be setThe sampling duration was 30ms at 25600 Hz.
The more the sampling points are, the better the conversion effect and the filtering effect are. The number of sampling points N may generally be taken to be to the power of 2 m (m is an integer), e.g., 128, 256, 512, 1024, etc. According to the scheme, through experimental debugging, the sampling point number N=256 is selected, and the precision requirement can be met.
At this time, the resolution j=of the AD converter. The smaller the J value, the higher the representative resolution, the better the effect of the AD converter, and the more accurate the result of the effective value.
If the resolution is to be improved, the number of sampling points is required to be increased, namely the sampling duration is increased, the resolution and the time are in inverse relation, and the longer the sampling duration is, the higher the resolution is, and the more accurate the experimental result is possible. However, in practical experiments, it is impossible to extend the sampling time without limitation, the sampling needs to be completed in a short time, and the K value should be selected to be within a reasonable range and not be excessively large.
Step 103, the AD converter determines an actual voltage code value and an actual current code value corresponding to the voltage code value and the current code value according to the amplification factor of the programmable gain amplifier, and performs FFT conversion on the actual voltage code value and the actual current code value, so as to obtain a frequency domain voltage code value and a frequency domain current code value corresponding to N sampling points.
And converting the acquired voltage code value and current code value to obtain an actual voltage code value and an actual current code value. To ensure accuracy, the two-precision floating point number Double is stored and sharedActual voltage code value and->The actual current code value.
For a pair ofActual voltage code value->And->Actual current code value->FFT (Fast Fourier Transformation, fast Fourier transform) conversion is respectively carried out to obtain frequency domain voltage code values of N sampling pointsAnd N sample points of the frequency domain current code value +.>。
The fourier transform can transform a time domain signal into a frequency domain signal, and help us analyze the spectral characteristics of the signal by calculating the amplitude and phase information of the signal at different frequencies. The frequency domain signal refers to the distribution of the signal over frequency, and the frequency refers to the number of periodic changes in the signal, expressed in Hertz (HZ).
The fast Fourier transform FFT is a fast algorithm of the discrete Fourier transform DFT, so that the operation process of the DFT is simplified, a precise result can be obtained, and the operation time is shortened by 1 to 2 orders of magnitude.
The working current of the lead-acid storage battery in a charging and discharging state contains harmonic components with different frequencies, and the amplitude is larger. Under the excitation of the AC discharge method, the harmonic components can also induce voltage signals at two ends of the lead-acid storage battery, so that the sampling signals contain multiple harmonics.
Although various filter circuits have been designed in the circuit in consideration of the presence of noise, ideal filters do not exist. The actually obtained sampling digital signal is also mixed with a large amount of noise, and the measurement accuracy of the resistance value is greatly reduced due to the existence of non-effective components when the existing methods such as a peak value method and the like are used for processing test data. On the basis of a hardware circuit, if the filter design can be completed in a software layer, the collected digital signals are subjected to software filter processing, and effective components in the signals are extracted, so that the measurement accuracy of the internal resistance can be improved. Spectral analysis of signals using fast fourier transforms is a very important tool for digital signal processing. It is proposed to process the sampled data by a fast fourier transform to extract the required frequency division amplitude, thereby improving the measurement accuracy of the internal resistance value.
Step 104, the micro control unit determines the effective voltage code value amplitude and the effective current code value amplitude of each sampling point under the target frequency according to the frequency domain voltage code value and the frequency domain current code value.
The FFT algorithm may convert the signal from the time domain to the frequency domain to obtain an array of complex numbers containing the amplitude and phase information of the signal at different frequencies.
Amplitude refers to the amplitude of a signal at a frequency that reflects the energy of the signal. The effective voltage code value amplitude and the effective current code value amplitude of each sampling point under the target frequency can be obtained through calculation or can be obtained through drawing a frequency domain image.
Step 105, the micro control unit determines the internal resistance of the target battery according to the reference voltage of the AD converter, the resolution of the AD converter, the effective voltage code value amplitude, the effective current code value amplitude, and the resistance value of the sampling resistor.
Since the ADC of each chip has a certain offset, it is biased to either positive or negative, or linear. Therefore, by converting the effective voltage code value amplitude and the effective current code value amplitude into the voltage value and the current value, there is a certain error in dividing the voltage value by the current value.
Because the target battery is connected with the sampling resistor in series, in the scheme, according to the reference voltage of the AD converter, the resolution of the AD converter and the effective voltage code value amplitude, the voltage values of two ends of the sampling resistor are calculated, and the voltage value of the sampling resistor is divided by the resistance value of the sampling resistor, so that the current value flowing through the target battery is obtained. And dividing the voltage value of the target battery by the current value flowing through the target battery to obtain the internal resistance of the target battery.
In summary, in the embodiment of the present invention, the signal source inputs an ac excitation signal with a target frequency to the target battery; the AD converter samples the voltage and the current of the target battery according to a preset sampling duration, a preset sampling point number and a preset sampling frequency to obtainVoltage code values and current code values of the data points; the sampling duration is K (K is more than or equal to 3) times of the alternating current excitation signal period, the number N of points is 2 to the power of m (m is an integer), and the sampling frequency is greater than or equal to N times of the target frequency; the AD converter determines an actual voltage code value and an actual current code value corresponding to the voltage code value and the current code value according to the amplification factor of the programmable gain amplifier, and performs FFT conversion on the actual voltage code value and the actual current code value respectively to obtain a frequency domain voltage code value and a frequency domain current code value corresponding to N sampling points; the micro control unit determines the effective voltage code value amplitude and the effective current code value amplitude of each sampling point under the target frequency according to the frequency domain voltage code value and the frequency domain current code value; the micro control unit determines the internal resistance of the target battery according to the reference voltage of the AD converter, the resolution of the AD converter, the effective voltage code value amplitude, the effective current code value amplitude and the resistance value of the sampling resistor. The alternating current excitation input by the scheme The excitation signal amplitude is smaller, the damage to the storage battery is small, the internal resistance measurement can be carried out under the working state and the non-working state of the storage battery, the resistance measurement precision is higher, and the analysis and the prediction of the battery are facilitated.
In one possible implementation, step 104 includes:
step 1041, placing the frequency domain voltage code values of the N sampling points into a first array according to a sampling sequence, and marking data point serial numbers for the effective data points by taking the data points except the first data point in the first array as the effective data points; the data point sequence number is a natural number starting from 2;
step 1042, placing the frequency domain current code values of the N sampling points into a second group according to the sampling sequence, and labeling each effective data point with the data point serial number;
step 1043, determining a first quotient of the sampling frequency and the target frequency;
step 1044, determining, for each data point in the first array, a second quotient of the first quotient and the data point sequence number;
step 1045, determining a product of the second quotient and the frequency domain voltage code value of the sampling point under the condition that the second quotient is an integer, so as to obtain an effective voltage code value amplitude of each effective data point under the target frequency;
Step 1046, for each data point in the second array, determining a product of a second quotient corresponding to the data point and the frequency domain current code value of the sampling point, to obtain an effective current code value amplitude of each effective data point at the target frequency.
In steps 1041-1046, the first number in the first array is 0HZ, i.e. the frequency without ripple, is a dc component, which needs to be eliminated. And taking the data points except the first data point as effective data points, and labeling the data point serial numbers for the effective data points. For example, labeled 2,3,4 … … N-1.
And executing the same operation on the second data group to obtain the data point serial numbers of all the valid data points.
In the first array and the second array, each data point represents an amplitude at a certain frequency. For example, the 1 st data point represents a frequency ofEffective amplitude under, kth point represents frequency +.>Effective amplitude, K. The excitation signal is required +.>Effective amplitude below.
The algorithm of FFT has two parameters when entering into parameters, the first parameter isA parameter representing the time domain, the second parameter being 1/>Representing the sampling interval. After FFT conversion, the frequency is obtained >The effective amplitude is [ ]xRepresent the firstxData points). The required frequency is +.>The effective amplitude of the lower is then satisfied +.>=/>Thus, it isx=Wherein->As a first quotient of the first and second quotient,xis the second quotient.
Thus, the effective voltage code value amplitude and the effective current code value amplitude are calculated as follows:
effective voltage code value amplitude（1）
Effective current code value amplitude（2）
Wherein,representing the frequency domain voltage code value, ">Sampling frequency->Represents the target frequency, N represents the number of sampling points, +.>Represents the frequency domain current code value, and +.>Is an integer.
For example, the number of the cells to be processed,the calculated value is 2, then the effective current code value amplitude +.>If (3)If the calculated value is not an integer, the value of the array cannot be directly extracted. For example, assume that the calculated value is 1.5, but since there is no +.>Such data requires a secondary processing of the data, such thatThe comparison consumes computing resources.
Therefore, in the condition of limited module resources, the module resources should be reasonably selected，/>And N, such that->The value of (2) is an integer, i.e.)>Should be +.>To improve test efficiency, save time and overhead.
In one possible implementation, after step 1044, the method further includes:
step 1047, inputting the first array and the second array into a target software if the second quotient is not an integer;
Step 1048, respectively drawing a voltage frequency domain image and a current frequency domain image corresponding to the frequency domain voltage code value and the frequency domain current code value by using the target software;
step 1049, determining an effective voltage code value amplitude of each effective sampling point at the target frequency by using the voltage frequency domain image;
step 1050, determining the effective current code value amplitude of each effective sampling point at the target frequency by using the current frequency domain image.
In steps 1047-1050, when the second quotient is not an integer, i.eIf the value is not an integer, the effective amplitude cannot be obtained by the formulas (1) and (2). At this time, the first array and the second array are input into the target software, and the voltage frequency domain image and the current frequency domain image are drawn by the target software to obtain the effective voltage code valueAmplitude and effective current code value amplitude.
The target software may specifically select software such as matlab or python that is capable of rendering a frequency domain image.
In one possible implementation, step 103 includes:
step 1031, determining the quotient of the voltage code value and the amplification factor of the programmable gain amplifier, and obtaining an actual voltage code value and an actual current code value by the quotient of the current code value and the amplification factor;
Step 1032, combining theThe actual voltage code value and the actual current code value of the data point are respectively put into a third array and a fourth array according to the sampling sequence;
step 1033, performing FFT conversion on the voltage code values in the third array to obtain frequency domain voltage code values corresponding to the N sampling points;
and 1034, performing FFT conversion on the actual current code values in the fourth array to obtain frequency domain current code values corresponding to the N sampling points.
In steps 1031-1034, the voltage code value and the current code value are first restored to the actual voltage code value and the actual current code value. Then willThe actual voltage code value of the data point is put into the third array,>the actual current code value of the data point is placed in the fourth array.
And performing FFT conversion on the third array and the fourth array respectively to obtain frequency domain voltage code values of N sampling points and frequency domain current code values of N sampling points.
In one possible implementation, step 105 includes:
step 1051, converting the effective voltage code value amplitude to an actual voltage value according to the reference voltage of the AD converter and the resolution of the AD converter.
In the embodiment of the invention, a calculation formula for converting the effective voltage code value amplitude into the actual voltage value is as follows:
（3）
Wherein,representing the actual voltage value, #>Representing the magnitude of the effective voltage code value, n representing the resolution of the AD converter,/for the voltage code value>Is the reference voltage of the AD converter.
Step 1052, converting the effective current code value amplitude to an actual current value according to the reference voltage of the AD converter, the resolution of the AD converter and the resistance value of the sampling resistor.
In the embodiment of the invention, a calculation formula for converting the effective current code value amplitude into the actual current value is as follows:
（4）
wherein,representing the actual current value, +.>Representing the magnitude of the effective current code value, n representing the resolution of the AD converter,/for the current code value>For the reference voltage of the AD converter, +.>Is the resistance of the sampling resistor.
Step 1053, taking the quotient of the actual voltage value and the actual current value as the internal resistance value of the target battery.
Specifically, the internal resistance value of the target batteryThe calculation formula of (2) is as follows:
（5）
wherein,representing the magnitude of the effective voltage code value, +.>Representing the magnitude of the effective current code value, +.>Is the resistance of the sampling resistor.
The scheme adopts an alternating current discharge method to measure the internal resistance of the battery, and has the advantages that compared with a direct current discharge method, the method comprises the following steps: the safety and reliability are realized; the excitation signal amplitude is smaller, and the damage to the lead-acid storage battery is small; the electromagnetic interference generated to other equipment in the power supply system is small; internal resistance measurement can be carried out in the working state and the non-working state of the lead-acid storage battery; the resistance measurement accuracy is higher, and the analysis and the prediction of the battery are facilitated.
In addition, the sampling data is processed by Fast Fourier Transform (FFT), and the required frequency division amplitude is extracted, so that the measurement accuracy of the internal resistance value is improved.
The invention also provides a battery internal resistance test system. As shown in fig. 1, the battery internal resistance test system includes a Micro Control Unit (MCU), an AD converter, a target battery to be tested, a sampling resistor, a signal source, and a Programmable Gain Amplifier (PGA): wherein, the signal source is used for:
inputting an alternating current excitation signal with a target frequency to the target battery;
the AD converter is used for:
according toSampling the voltage and the current of the target battery by a preset sampling duration, a preset sampling point number and a preset sampling frequency to obtainVoltage code values and current code values of the data points; the sampling duration is K (K is more than or equal to 3) times of the alternating current excitation signal period, the number N of points is 2 to the power of m (m is an integer), and the sampling frequency is greater than or equal to N times of the target frequency;
determining an actual voltage code value and an actual current code value corresponding to the voltage code value and the current code value according to the amplification factor of the programmable gain amplifier, and performing FFT (fast Fourier transform) on the actual voltage code value and the actual current code value respectively to obtain a frequency domain voltage code value and a frequency domain current code value corresponding to N sampling points;
The micro control unit is used for:
according to the frequency domain voltage code value and the frequency domain current code value, determining the effective voltage code value amplitude and the effective current code value amplitude of each sampling point under the target frequency;
and determining the internal resistance of the target battery according to the reference voltage of the AD converter, the resolution of the AD converter, the effective voltage code value amplitude, the effective current code value amplitude and the resistance value of the sampling resistor.
The specific manner in which the various modules perform the operations in relation to the systems of the above embodiments have been described in detail in relation to the embodiments of the method and will not be described in detail herein.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), memory bus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.
Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any adaptations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
It is to be understood that the present disclosure is not limited to the precise arrangements and instrumentalities shown in the drawings, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.
Claims (10)
1. A battery internal resistance testing method, characterized in that it is applied to a battery internal resistance testing system, the battery internal resistance testing system includes a micro control unit, an AD converter, a target battery to be tested, a sampling resistor, a signal source and a programmable gain amplifier, the method includes:
the signal source inputs an alternating current excitation signal with a target frequency to the target battery;
The AD converter samples the voltage and the current of the target battery according to a preset sampling duration, a preset sampling point number and a preset sampling frequency to obtainVoltage code values and current code values of the data points; the sampling duration is K (K is more than or equal to 3) times of the alternating current excitation signal period, the number N of points is 2 to the power of m (m is an integer), and the sampling frequency is greater than or equal to N times of the target frequency;
the AD converter determines an actual voltage code value and an actual current code value corresponding to the voltage code value and the current code value according to the amplification factor of the programmable gain amplifier, and performs FFT conversion on the actual voltage code value and the actual current code value respectively to obtain a frequency domain voltage code value and a frequency domain current code value corresponding to N sampling points;
the micro control unit determines the effective voltage code value amplitude and the effective current code value amplitude of each sampling point under the target frequency according to the frequency domain voltage code value and the frequency domain current code value;
the micro control unit determines the internal resistance of the target battery according to the reference voltage of the AD converter, the resolution of the AD converter, the effective voltage code value amplitude, the effective current code value amplitude and the resistance value of the sampling resistor.
2. The method of claim 1, wherein said determining the effective voltage code value amplitude and the effective current code value amplitude for each of the sampling points at the target frequency from the frequency domain voltage code value and the frequency domain current code value comprises:
placing the frequency domain voltage code values of the N sampling points into a first array according to a sampling sequence, taking the sampling points except the first sampling point in the first array as effective sampling points, and labeling sampling point serial numbers for the effective sampling points; the sampling point sequence number is a natural number from 2;
the frequency domain current code values of the N sampling points are put into a second group according to the sampling sequence, and the sampling point serial numbers are marked for the effective sampling points;
determining a first quotient of the sampling frequency and the target frequency;
for each sampling point in the first array, determining a second quotient of the first quotient and the sampling point sequence number;
under the condition that the second quotient is an integer, determining the product of the second quotient and the frequency domain voltage code value of the sampling point to obtain the effective voltage code value amplitude of each effective sampling point under the target frequency;
And for each sampling point in the second array, determining the product of a second quotient corresponding to the sampling point and the frequency domain current code value of the sampling point to obtain the effective current code value amplitude of each effective sampling point under the target frequency.
3. The method of claim 2, further comprising, after determining the second quotient of the first quotient and the sample point sequence number:
inputting the first array and the second array into target software if the second quotient is not an integer;
drawing a voltage frequency domain image and a current frequency domain image corresponding to the frequency domain voltage code value and the frequency domain current code value respectively by utilizing the target software;
determining the effective voltage code value amplitude of each effective sampling point under the target frequency by utilizing the voltage frequency domain image;
and determining the effective current code value amplitude of each effective sampling point at the target frequency by using the current frequency domain image.
4. The method according to claim 1, wherein determining an actual voltage code value and an actual current code value corresponding to the voltage code value and the current code value according to the amplification factor of the programmable gain amplifier, and performing FFT conversion on the actual voltage code value and the actual current code value, respectively, includes:
Respectively determining the quotient of the voltage code value and the amplification factor of the programmable gain amplifier, and obtaining an actual voltage code value and an actual current code value by the quotient of the current code value and the amplification factor;
the saidThe actual voltage code value and the actual current code value of the data point are respectively put into a third array and a fourth array according to the sampling sequence;
performing FFT conversion on the voltage code values in the third array to obtain frequency domain voltage code values corresponding to N sampling points;
and carrying out FFT conversion on the actual current code values in the fourth array to obtain frequency domain current code values corresponding to the N sampling points.
5. The method according to claim 1, wherein the determining the internal resistance of the target battery based on the reference voltage of the AD converter, the resolution of the AD converter, the effective voltage code value amplitude, the effective current code value amplitude, and the resistance value of the sampling resistor includes:
converting the effective voltage code value amplitude into an actual voltage value according to the reference voltage of the AD converter and the resolution of the AD converter;
converting the effective current code value amplitude into an actual current value according to the reference voltage of the AD converter, the resolution of the AD converter and the resistance value of the sampling resistor;
Taking the quotient of the actual voltage value and the actual current value as the internal resistance value of the target battery.
6. The battery internal resistance test system is characterized by comprising a micro control unit, an AD converter, a target battery to be tested, a sampling resistor, a signal source and a programmable gain amplifier: wherein, the signal source is used for:
inputting an alternating current excitation signal with a target frequency to the target battery;
the AD converter is used for:
according to the preset sampling duration and the preset sampling pointSampling the voltage and the current of the target battery by the number and the preset sampling frequency to obtainVoltage code values and current code values of the data points; the sampling duration is K (K is more than or equal to 3) times of the alternating current excitation signal period, the number N of points is 2 to the power of m (m is an integer), and the sampling frequency is greater than or equal to N times of the target frequency;
determining an actual voltage code value and an actual current code value corresponding to the voltage code value and the current code value according to the amplification factor of the programmable gain amplifier, and performing FFT (fast Fourier transform) on the actual voltage code value and the actual current code value respectively to obtain a frequency domain voltage code value and a frequency domain current code value corresponding to N sampling points;
The micro control unit is used for:
according to the frequency domain voltage code value and the frequency domain current code value, determining the effective voltage code value amplitude and the effective current code value amplitude of each sampling point under the target frequency;
and determining the internal resistance of the target battery according to the reference voltage of the AD converter, the resolution of the AD converter, the effective voltage code value amplitude, the effective current code value amplitude and the resistance value of the sampling resistor.
7. The system according to claim 6, wherein the micro control unit is specifically configured to:
placing the frequency domain voltage code values of the N sampling points into a first array according to a sampling sequence, taking the sampling points except the first sampling point in the first array as effective sampling points, and labeling sampling point serial numbers for the effective sampling points; the sampling point sequence number is a natural number from 2;
the frequency domain current code values of the N sampling points are put into a second group according to the sampling sequence, and the sampling point serial numbers are marked for the effective sampling points;
determining a first quotient of the sampling frequency and the target frequency;
for each sampling point in the first array, determining a second quotient of the first quotient and the sampling point sequence number;
Under the condition that the second quotient is an integer, determining the product of the second quotient and the frequency domain voltage code value of the sampling point to obtain the effective voltage code value amplitude of each effective sampling point under the target frequency;
and for each sampling point in the second array, determining the product of a second quotient corresponding to the sampling point and the frequency domain current code value of the sampling point to obtain the effective current code value amplitude of each effective sampling point under the target frequency.
8. The system of claim 7, wherein the micro-control unit is further configured to:
inputting the first array and the second array into target software if the second quotient is not an integer;
drawing a voltage frequency domain image and a current frequency domain image corresponding to the frequency domain voltage code value and the frequency domain current code value respectively by utilizing the target software;
determining the effective voltage code value amplitude of each effective sampling point under the target frequency by utilizing the voltage frequency domain image;
and determining the effective current code value amplitude of each effective sampling point at the target frequency by using the current frequency domain image.
9. The system of claim 6, wherein the AD converter is specifically configured to:
Respectively determining the quotient of the voltage code value and the amplification factor of the programmable gain amplifier, and obtaining an actual voltage code value and an actual current code value by the quotient of the current code value and the amplification factor;
the saidActual voltage code value and actual current of data pointThe code value is respectively put into a third array and a fourth array according to the sampling sequence;
performing FFT conversion on the voltage code values in the third array to obtain frequency domain voltage code values corresponding to N sampling points;
and carrying out FFT conversion on the actual current code values in the fourth array to obtain frequency domain current code values corresponding to the N sampling points.
10. The system according to claim 6, wherein the micro control unit is specifically configured to:
converting the effective voltage code value amplitude into an actual voltage value according to the reference voltage of the AD converter and the resolution of the AD converter;
converting the effective current code value amplitude into an actual current value according to the reference voltage of the AD converter, the resolution of the AD converter and the resistance value of the sampling resistor;
taking the quotient of the actual voltage value and the actual current value as the internal resistance value of the target battery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311442315.7A CN117148191A (en) | 2023-11-01 | 2023-11-01 | Method and system for testing internal resistance of battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311442315.7A CN117148191A (en) | 2023-11-01 | 2023-11-01 | Method and system for testing internal resistance of battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117148191A true CN117148191A (en) | 2023-12-01 |
Family
ID=88897318
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311442315.7A Pending CN117148191A (en) | 2023-11-01 | 2023-11-01 | Method and system for testing internal resistance of battery |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117148191A (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1967270A (en) * | 2005-11-18 | 2007-05-23 | 北华大学 | Method and system for testing battery impedance spectroscopy |
| CN104950180A (en) * | 2015-06-02 | 2015-09-30 | 国电南京自动化股份有限公司 | Method for precisely measuring internal resistance of single storage batteries on basis of EIS (electrochemical impedance spectroscopy) |
| CN204789762U (en) * | 2015-06-29 | 2015-11-18 | 国电南京自动化股份有限公司 | Practical monomer holds internal resistance of cell measurement circuit |
| CN107843855A (en) * | 2017-12-14 | 2018-03-27 | 株洲广锐电气科技有限公司 | Accumulator internal resistance detecting system |
| CN110231581A (en) * | 2019-06-10 | 2019-09-13 | 哈尔滨佳云科技有限公司 | Accumulator internal resistance measuring circuit and measurement method |
| CN110376438A (en) * | 2019-08-06 | 2019-10-25 | 黑龙江省计量检定测试研究院 | Internal resistance of power lithium battery detection device and its detection method |
| CN111580006A (en) * | 2020-05-29 | 2020-08-25 | 中国电力科学研究院有限公司 | Online measurement method and system for dynamic impedance of battery |
| CN115494414A (en) * | 2022-10-26 | 2022-12-20 | 大连理工大学 | Online real-time monitoring system and method for internal resistance of energy storage battery |
-
2023
- 2023-11-01 CN CN202311442315.7A patent/CN117148191A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1967270A (en) * | 2005-11-18 | 2007-05-23 | 北华大学 | Method and system for testing battery impedance spectroscopy |
| CN104950180A (en) * | 2015-06-02 | 2015-09-30 | 国电南京自动化股份有限公司 | Method for precisely measuring internal resistance of single storage batteries on basis of EIS (electrochemical impedance spectroscopy) |
| CN204789762U (en) * | 2015-06-29 | 2015-11-18 | 国电南京自动化股份有限公司 | Practical monomer holds internal resistance of cell measurement circuit |
| CN107843855A (en) * | 2017-12-14 | 2018-03-27 | 株洲广锐电气科技有限公司 | Accumulator internal resistance detecting system |
| CN110231581A (en) * | 2019-06-10 | 2019-09-13 | 哈尔滨佳云科技有限公司 | Accumulator internal resistance measuring circuit and measurement method |
| CN110376438A (en) * | 2019-08-06 | 2019-10-25 | 黑龙江省计量检定测试研究院 | Internal resistance of power lithium battery detection device and its detection method |
| CN111580006A (en) * | 2020-05-29 | 2020-08-25 | 中国电力科学研究院有限公司 | Online measurement method and system for dynamic impedance of battery |
| CN115494414A (en) * | 2022-10-26 | 2022-12-20 | 大连理工大学 | Online real-time monitoring system and method for internal resistance of energy storage battery |
Non-Patent Citations (1)
| Title |
|---|
| （美）ROBERT A.PEASE著；刘波文译: "模拟电路", 31 July 2014, 北京航空航天大学出版社 , pages: 338 - 342 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Yao et al. | Fast S-transform for time-varying voltage flicker analysis | |
| CN111007450A (en) | Method for detecting result reliability of load identification equipment | |
| CN108387824B (en) | Oiled paper insulation state evaluation method for improving return voltage measurement mode | |
| Serfontein et al. | Continuous event-based harmonic impedance assessment using online measurements | |
| CN109459465B (en) | Rapid electrochemical impedance spectrum measurement method based on current pulse injection | |
| Djurić et al. | Frequency measurement of distorted signals using Fourier and zero crossing techniques | |
| CN114879085B (en) | Single-phase earth fault identification method and device, electronic equipment and medium | |
| CN103229062A (en) | Method for measurement of total harmonic distortion | |
| CN105675994A (en) | Measuring method for equivalent system harmonic impedance of feeder line in power distribution network | |
| Manganiello et al. | FPGA implementation of the EIS technique for the on-line diagnosis of fuel-cell systems | |
| Tran et al. | Realtime internal-impedance measurement of lithium-ion battery using discrete-interval-binary-sequence injection | |
| CN117148191A (en) | Method and system for testing internal resistance of battery | |
| Li et al. | An improved battery on-line parameter identification and state-of-charge determining method | |
| CN115219787A (en) | Power grid phasor movement measurement method, system and medium based on improved matrix bundle | |
| CN114325057B (en) | PT primary voltage reconstruction method based on inverse black box and inverse electromagnetic dual model | |
| CN115086361A (en) | Analysis system and method for monitoring data of motor train unit, electronic device and storage medium | |
| Chang et al. | A new procedure for tracking the source location | |
| Qingfeng et al. | Fault detection of rectifier based on residuals | |
| Islam et al. | High precision on-line impedance measurement for a li-ion battery | |
| Peretto et al. | The effect of the Integration Interval on the Measurement Accuracy of rms Values and Powers in Systems with Nonsinusoidal Wavefo | |
| Shadmehr et al. | Beyond FFT algorithm in analyzing harmonics at frequency range of 2 kHz to 500 kHz | |
| Radil et al. | Detection and extraction of harmonic and non-harmonic power quality disturbances using sine fitting methods | |
| Cervera et al. | PEMFC impedance spectroscopy using synthetic wide-band signals | |
| Michalski et al. | Estimation of parameters for obnoxious load which does not increase amplitude of voltage fluctuations | |
| KR20140013465A (en) | System and method for measuring harmonic distortion ratio in watt-hour meter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |