In recent years, method of testing has obtained Hesperian extensive approval to adopt internal resistance/conductivity test technology to carry out simply fast to state-of-charge (SOC), the cell health state (SOH) of battery, and this technology has been classified as the testing standard of analysing valve control type lead-acid accumulator battery (VRLA) by International Electrotechnical Commission (IEEE).
Ieee standard (1118-1996) is gone up explanation: the measurement of battery conductance is the two ends that the alternating voltage of given frequency and amplitude are added to battery, measures the electric current that is produced then.The conductance for alternating current value is exactly to change the variation that (descending greater than 20%) just means battery performance with the alternating current component of alternating voltage homophase and the tangible electric conductivity value of ratio of alternating voltage.
The internal resistance of cell measuring method of using in the industry mainly contains following two kinds at present:
1, direct-current discharge internal resistance measurement method
By testing apparatus allow battery at short notice (be generally 2-3 second) force to measure the voltage at battery two ends this moment by a very big Constant Direct Current electric current, and calculate the current internal resistance of cell by the variable quantity of voltage and the variable quantity of electric current.This method can only be measured the DC internal resistance of battery.
2, exchange pressure drop internal resistance measurement method
On battery, apply the electric current of a fixed frequency and fixed amplitude, then sampled measurements is carried out in its voltage responsive, calculate the impedance of battery by alternating current flow valuve and magnitude of voltage.Because the impedance of battery is the function of frequency, its impedance is different under different frequencies, and therefore, the impedance spectrum that measure battery just needs constantly the dull frequency that changes exciting current, repeats above-mentioned measuring process, and the test duration is long, efficient is low.
In recent years, both at home and abroad SOC, the SOH of battery and the correlative study of the internal resistance of cell are shown, the impedance of the SOC of battery, SOH and battery has inherent getting in touch and close correlativity, if can adopt otherwise effective technique and measuring method, battery is measured in the AC impedance under the different frequency, particularly carry out fast on-line measurement, all have important use to be worth research, processing technology and the technological improvement of battery mechanism and the accurate prediction of SOC, SOH in the use.
Summary of the invention
Goal of the invention
The purpose of this invention is to provide a kind of method and system that can finish battery impedance spectrum measurement and analysis at short notice fast.
For realizing quick test battery impedance spectrum, the present invention adopts following method and system:
A kind of battery impedance spectroscopy method of testing may further comprise the steps:
(1) on measured battery, applies the current excitation I (t) of a square wave or approximate square wave;
(2) synchro measure current excitation I (t) and terminal voltage response U (t);
(3) calculate the amplitude frequency spectrum I (ω that current excitation I (t) under the multiple frequency and terminal voltage respond U (t) with current excitation I (t) that measure to gather and terminal voltage response U (t)
k), U (ω
k) and phase frequency spectrum φ
(4) can calculate the anti-Z of the internal resistance of cell under multiple frequency according to the frequency spectrum of I and U
k).Thereby can draw the anti-complete spectrogram of the internal resistance of cell.
The computing method of amplitude frequency spectrum and phase frequency spectrum are to adopt FFT (FastFourier Transform fast fourier transform) or wavelet analysis technology to calculate F[I (t) in step (3)]=I (e
J ω), F[U (t)]=U (e
A kind of battery impedance spectrum testing system comprises that control and data processing unit, high-speed synchronous sampled measurements unit, voltage and current signal are isolated the conditioning unit, control module, controlled discharge unit discharge.Control and data processing unit control high-speed synchronous sampled measurements unit, and by discharge control module control controlled discharge unit starting with stop, calculating that finishing impedance spectrum according to the electric current and the voltage signal of the unit collection of high-speed synchronous sampled measurements; Voltage and current signal is isolated electric current and the voltage signal that battery is gathered in the conditioning unit, and sends high-speed synchronous sampled measurements unit to after isolating conditioning; High-speed synchronous sampled measurements unit carries out high-speed synchronous collection and buffer memory to electric current and voltage signal, and send the signal of gathering to control and data processing unit, analyze and handle for control and data processing unit, the controlled discharge unit discharges to battery by discharge time and the current amplitude set under the control of discharge control module.
Wherein, the discharge control module is one or more photoelectricity isolation coupling switches, receives the control signal of control and data processing unit, according to this control signal control controlled discharge unit.
Wherein, the controlled discharge unit comprises one or morely forms discharge load by N-channel MOS FET and discharge resistance, and each N-channel MOS FET and discharge resistance are formed discharge load and controlled it by the discharge control module and be switched on or switched off discharge load.
1, can finish battery impedance spectrum measurement and analysis at short notice fast.Be generally several ms～hundreds of ms discharge time.Improved efficiency of measurement greatly.
2, the fundamental frequency of current excitation be can adjust by adjustment discharge time, and the internal impedance of some frequency range or frequency more accurate measurement and analysis carried out by signal processing technologies such as FFT, digital filtering, wavelet analysises.
3, can utilize battery in the course of the work shelve gap, the online measurement of finishing battery impedance spectroscopy.
4, the battery impedance of battery impedance spectroscopy under the single fixed frequency can more comprehensively reflect the SOC and the SOH of battery, for calculating and the prediction of SOC and SOH provides a kind of new solution.
Following examples are used to illustrate the present invention; but be not used for limiting the scope of the invention; the those of ordinary skill in relevant technologies field; under the situation that does not break away from spirit and scope of the present utility model; can also make various variations and modification; therefore all technical schemes that are equal to also belong to category of the present invention, and scope of patent protection of the present invention should be limited by every claim.
1, measures ultimate principle
In fact battery can be equivalent to it active network, as current excitation I (the t)=I that applies a certain frequency on battery
t), then the terminal voltage at battery has corresponding response U (t)=U
t+ ψ).Change the frequencies omega of current excitation I (t),, can calculate the internal impedance Z (ω) of battery under different frequency by measuring corresponding terminal voltage response U (t).
According to this ultimate principle, this programme has proposed the anti-measuring method of a kind of new internal resistance of cell, and measuring principle is as follows:
On battery, apply the current excitation I (t) of a square wave or approximate square wave, synchro measure current excitation I (t) and terminal voltage response U (t), adopt FFT (Fast Fourier Transform fast fourier transform) or wavelet analysis technology:
Can calculate the amplitude frequency spectrum I (ω of current excitation I (t) under the multiple frequency and terminal voltage response U (t) simultaneously
k), U (ω
k) and phase frequency spectrum φ
Can calculate the anti-Z of the internal resistance of cell under multiple frequency according to the frequency spectrum of I and U
k).Thereby can draw the anti-complete spectrogram of the internal resistance of cell.Measuring principle as shown in Figure 1.
2, measure implementation method
Measuring system is made of control and data processing unit, high-speed synchronous sampled measurements unit, controlled discharge unit.The structure of system as shown in Figure 2, hardware is formed as shown in Figure 3.
(1) control and data processing unit:
Adopt built-in PC 104CPU module, basic configuration is as follows:
Embedded Pentium (200,300MHz) CPU, 128M internal memory, 40GHD, 640 * 480 color LCDs;
VGA, USB, RS232 serial ports, parallel port, keyboard interface, real-time clock;
24 programmable digital I/O.
(2) voltage and current signal is isolated the conditioning unit
A PhotoMOS relay K s, current-limiting resistance R2, voltage keeps capacitor C
H, a termination of current-limiting resistance detects the positive pole of battery, and the other end is connected with the utmost point of relay K s and the positive input of voltage differential operational amplifier AD620, and voltage keeps capacitor C
HA utmost point connect the negative pole of detected battery, the other end connects another utmost point of relay K s, and directly or by the negative input that a leak resistor R3 is connected to voltage differential operational amplifier AD620 connects;
1s) the positive pole of the detected battery of a termination, and directly or be connected to the positive input of current-differencing operational amplifier A D620 by current signal resistance (R4), one utmost point of another termination controlled discharge unit, and directly or by current signal resistance (R5) being connected to the negative input of current-differencing operational amplifier A D620, another utmost point of controlled discharge unit connects the negative pole of detected battery.
(3) high-speed synchronous sampled measurements unit
Employing has 14 single-ended 4 tunnel synchronous nothings and differs 200K A/D, ± 5V range, and the USB2007 data acquisition module of 32K word FIFO storer is to measuring through the voltage and current signal after the Signal Spacing conditioning unit conditioning.
For improving voltage measurement resolution, in Signal Spacing conditioning unit, adopt the PhotoMOS relay K
S, the battery quiescent voltage keeps capacitor C
HWith the circuit that differential operational amplifier AD620 forms cell voltage dynamic response increment Delta U (t) is measured, its ultimate principle is:
When battery is in static state (shelving state), control K
SMake its conducting, battery passes through K
STo keeping capacitor C
HCharge, because this moment is by C
3The RC constant of charge circuit is R
H=200 Ω * 5 μ F=1ms, therefore C within 10ms
HOn voltage V
CHCan reach the quiescent voltage U (0) of battery;
When beginning that cell voltage dynamic response increment Delta U (t) when measuring, is at first turn-offed K
S, by discharge loop battery being applied the current excitation I (t) of a square wave or approximate square wave then, the voltage responsive of generation is U (t), then
Send after sending AD620 to amplify the Δ U (t) and isolate operational amplifier A D210, give USB2007 data acquisition module AIN0.
To by the PhotoMOS relay with keep capacitor C
HΔ U (t) measured deviation that leakage current produced can be revised by following formula
(2) T in the formula
SFor measuring the sampling period; N is a measure dot number; Δ U (nT
S) be that revised Δ U (t) is at nT
SMeasured value constantly; Δ U
S) be that uncorrected Δ U (t) is at nT
SMeasured value constantly.K
DVFor keeping the voltage fall off rate of electric capacity during keeping, when PhotoMOS relay and maintenance capacitor C
HAfter determining, K
DVBe a constant, K
DVCan when being in static state, demarcate by battery.
150A shunt R is adopted in current measurement
1sMeasure, send after the mV magnitude voltage signals send AD620 to amplify on the shunt and isolate operational amplifier A D210, give USB2007 data acquisition module AIN1.
(4) controlled discharge unit
Hardware is formed as shown in Figure 3.
Employing is formed discharge load by 8 N-channel MOS FET and discharge resistance, by control and 8 bit digital delivery outlets of data processing unit by 8 74LS04 photoelectricity isolation after, the conducting of 8 MOSFET of control and ending, and realize the classification adjustment of discharge current by 8 MOSFET conductings and the combination that ends.
MOSFET K1, K2 ... K8 adopts APT10M07JVFR, V
DS (on)=0.007 Ω;
Discharge resistance R
L8Be respectively 0.8 Ω, 0.4 Ω, 0.2 Ω, 0.1 Ω, 0.08 Ω, 0.04 Ω, 0.02 Ω, 0.01 Ω, power is 200W.
By adjusting the turn-on and turn-off time of MOSFET, the time of adjustable current square wave excitation, promptly adjust the frequency of first-harmonic, with the measuring accuracy of further raising impedance under this fundamental frequency.
3, data acquisition and processing (DAP) software flow
Software block diagram as shown in Figure 4.
Native system adopts the LabView virtual instrument software platform to work out, and the host process of software is finished the parameter setting, tasks such as test starting and test process control, Data Management Analysis; AD conversion thread is controlled the USB2007 data acquisition module, finishes the synchronized sampling of electric current and voltage.
4, concrete measuring process is as follows:
Control and data processing unit at first start high-speed synchronous sampled measurements unit and carry out data acquisition, starting the controlled discharge unit then discharges to tested battery, when reaching discharge time, close discharge cell and stop discharge, and then stop the data acquisition of high-speed synchronous sampled measurements unit, control and data processing unit are analyzed and are handled signal by the measurement ultimate principle that the present invention proposes, and calculate the internal impedance frequency spectrum of battery.