WO2001050119A1 - Procede et appareil destines a mesurer les impedances de cellule et de batterie electrochimiques - Google Patents

Procede et appareil destines a mesurer les impedances de cellule et de batterie electrochimiques Download PDF

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Publication number
WO2001050119A1
WO2001050119A1 PCT/US2000/035044 US0035044W WO0150119A1 WO 2001050119 A1 WO2001050119 A1 WO 2001050119A1 US 0035044 W US0035044 W US 0035044W WO 0150119 A1 WO0150119 A1 WO 0150119A1
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Prior art keywords
impedance
current
battery
sensing
path
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Application number
PCT/US2000/035044
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English (en)
Inventor
James D. Kozlowski
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The Penn State Research Foundation
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Publication date
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Priority to AU41336/01A priority Critical patent/AU4133601A/en
Publication of WO2001050119A1 publication Critical patent/WO2001050119A1/fr

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    • 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

Definitions

  • This invention relates to techniques for measuring impedance in electrochemical cells. More particularly, the invention is directed to apparatuses and methods used for taking internal impedance measurements of electrochemical batteries and cells with improved sensitivity and noise/electromagnetic immunity as compared to currently existing methods.
  • Electrochemical batteries and cells have very low internal impedance. This is true in different types of cells, including those based on either lead acid or nickel cadmium chemistries
  • These circuits generally include impedance elements 22 that are located along first and second current paths 24 and 26, the impedance elements 22 being located on either side of voltage divider points where the voltages V A and VB can be measured.
  • impedance elements 22 For battery impedance measurements, one of the impedance elements 22 in the bridge represents the battery being measured.
  • the output of the bridge, V 0 is the potential difference between V A and V B .
  • V 0 is equal to zero (i.e. VA - VB ), so that
  • one way of using this circuit is to make one of the impedance elements 22 adjustable and adjust the value of the impedance until V 0 is equal to zero.
  • the problem with this type of operation is that it requires continuous adjustment of the element for each frequency at which the measurement is made. This is because battery impedance is not constant over the frequency spectrum of interest.
  • An automated system for handling such a procedure is complex and difficult to implement.
  • This circuit is typically used by picking nominal values of the three known impedance elements 22 to maximize the output voltage swing as the battery impedance changes through the sweep of frequencies and usable life.
  • bridge circuits Another limitation of bridge circuits relates to the fact that since internal impedance is very low for most cell types, voltage drops across the battery will also be very low. Fixing the values of all but one impedance element 22 and allowing only this battery impedance element to change implies that either V A or V B will remain constant.
  • the bridge 20 reduces to a voltage divider for changes in the battery impedance. The output voltage is inversely proportional to changes in the battery impedance. Thus, as the impedance of the battery increases, output voltage becomes smaller. To get sufficiently large voltage drops at the output, a large amount of current is required. For example, if the magnitude of the battery impedance were 5m ⁇ , a 1A
  • the input impedance of such an amplifier would be the impedance of the bridge circuit 20 and would be very low due to the low battery impedance.
  • amplifiers become highly susceptible to electrical field noise, whether self-generated or from other sources. This condition is compounded where the input signal is also very low. Adverse interference effects can be expected regardless of whether BJT or FET input stages are used.
  • an added transformer can reduce the bandwidth of the output signal produced.
  • bridge circuits do not easily permit impedance sensing without adjustment of the known impedance elements 22, the circuit has no more sensitivity than the voltage divider circuit. Thus, such circuits are normally only usable in laboratory settings where the impedance elements can be adjusted.
  • a second commonly used technique for impedance measuring uses a voltage divider circuit, which is typically preferred over bridge circuits when adjustment of impedance is not required.
  • a voltage divider circuit 28 used for battery impedance measurements is shown in FIG. 2.
  • the circuit 28 like most designs of this type, is driven by an AC current source 30 since voltage levels are typically in the range of millivolts and current in the range of amperes and thus amperage is easier to regulate than voltage.
  • the circuit includes a sensing impedance Z s and a battery impedance Zb in a series loop 29 with the AC current source. Each sensing and battery impedance has a respective sensor 31 that connects to the series loop 29 at the respective impedance's point of positive and negative potential.
  • Each sensor 31 is separated from the series loop 29 by capacitors 32 used to block the battery's DC signal.
  • This technique involves two measurements: (1) measurement of the voltage V s across a sensing impedance Z S; permitting measurement of the loop current given the known size of Z s ; and (2) measurement of the voltage Vb across the battery 34 being measured.
  • Voltage divider circuits used to measure battery impedance are limited by the same disadvantages as bridge circuits. Like bridge circuits, voltage measurements are taken in the millivolt signal level since batteries have very low impedance. Thus, voltage divider circuits, like bridge circuits, are susceptible to electrical field noise and have limited sensitivity.
  • a third technique utilizes a circuit known as a 4-wire or "Kelvin" connection. This is among the most frequently used techniques for measuring battery impedance and has been described in numerous patents and other references.
  • the general configuration of a 4-wire connection 36 is shown in FIG. 3. In principle, this circuit is very similar to a voltage divider circuit, being driven by a current source 37. But the 4-wire connection 36 does not have a sensing impedance Z s .
  • a battery 38 is interrogated with a current signal, and the voltage drop Vb across the battery 38 is measured with a sensor 31 separated from the battery nodes by capacitors 32. As indicated above, for most lead acid and nickel cadmium cells, the internal impedance Zb is very low. This means that the battery 38 will be driven with amperes of current, and output signals will be on the order of millivolts of potential.
  • output signals on the order of tens of millivolts require input signals on the order of tens of amperes.
  • sensitivity tends to be inversely related to the impedance of a battery. Since larger cell sizes ultimately lead to progressively smaller internal impedances, then for progressively larger cells, output voltages produced using the 4- wire technique tend to be smaller for the same input current. It follows that this technique is generally inadequate for using in a broad range of cell sizes.
  • FIG. 4 A simplified illustration of a short circuit 40 is shown in FIG. 4.
  • the circuit has a switch 41 connected to the positive node of a battery 42 having an impedance Zb.
  • the battery's negative node is grounded, while the switch 41 connects the positive node to a current mirror 43 and to ground 45.
  • This technique simply involves taking a voltage measurement on the unloaded battery 42 followed by a measurement of the short-circuited current to calculate a measure of the battery's internal impedance Zb.
  • the short circuit is only applied long enough to get an accurate enough measurement of the discharge current.
  • this technique is useful for calculating impedance in small, lithium iodine batteries, other larger battery types, including larger lithium iodine and most lead acid batteries, pose a serious explosion hazard when similarly short circuited.
  • This technique is also limited in that it can only be used to get a bulk number to represent the battery's internal impedance, which eliminates all phase and frequency related information.
  • One additional technique that is commonly used to measure battery impedance is the time-constant method. As demonstrated in the example circuit in FIG. 5, this method is based on the concept of an RC time response of a battery 44 where R is contributed from a battery 46 and a capacitor 45 is a selected known value C.
  • the battery is connected between ground and a normally-open switch 47 which is connected through capacitor 45 to ground.
  • the charge V c across the capacitor 45 can be monitored through operational amplifier 49.
  • switch 47 is closed, causing the battery voltage Vbto discharge through battery resistance Rb to charge capacitor 45.
  • the battery's internal impedance is assumed to be a resistive element and the resulting measurement is reduced to a bulk number. No information about phase or frequency contributions is measured or determined.
  • the technique is also limited in that there is a necessary tradeoff between capacitor size and processing speed of the detection circuit. A larger capacitor requires a larger amount of energy to be drawn from the battery, while the smaller the capacitors, the less time there is for the detection circuit to determine the time constant, affecting the sensitivity of the circuit. This relative dependence on the capacitor's size ultimately affects the circuit's sensitivity.
  • battery impedance Z s of a battery is measured by a circuit, such as a current divider network which is connected to the battery.
  • the circuit has a current generator producing a current signal Ii and has one or more sensing impedances Z s which are normally positioned electrically parallel, or in some alternate embodiments in series, with the battery.
  • a DC-blocking capacitor is positioned in series with the battery to prevent the battery voltage from draining into the one or more sensing impedances Z s .
  • a magnetic field sensor or comparable device for measuring the electromagnetic field produced by the current flowing through a wire is then used to measure the current I s passing through the sensing impedances Z s . Either the magnitude or the phase, or both, of I s can be measured to arrive at a usable value.
  • the value of the impedance is mathematically determined. This can be done, for example, by substituting a number of calibrated impedances having values Z oa ⁇ through Z ca i N , into the circuit in place of the battery and its impedance value Zb.
  • the mathematical determination includes accounting for the effects of the combined circuit and connector impedances Zl and Z2 which lead, respectively, into the parallel sensing and battery impedances Z s and Zb. An additional accounting is made for the effect of the combined circuit and connector impedance Z3 leading out of the sensing impedance Z s and the combined circuit, connector and blocking capacitor impedance Z4 leading out of the battery impedance Zb. This results in the relationship:
  • Z b I s (Zs + Zl + Z3) + (Z2 + Z4) where the values of Zl, Z2, Z3, and Z4 may be unknown.
  • two calibrated impedances Z ca ⁇ and Z ca ⁇ 2 are substituted into the circuit for the battery impedance Zb where:
  • the invention does not reside in any one of the features of the impedance measuring apparatus and method which is disclosed above and in the Detailed Description of the Preferred Embodiments and claimed below. Rather, this invention is distinguished from the prior art by its particular combination of features disclosed. Important features of this invention have been disclosed in the Detailed Description of the Preferred Embodiments of this invention which are shown and described below, to illustrate the best mode contemplated to date of carrying out this invention.
  • FIG. 1 depicts a typical bridge circuit configuration of the type commonly used in one impedance measuring technique of the prior art
  • FIG. 2 depicts a typical voltage divider configuration of the type commonly used in an additional impedance measuring technique of the prior art
  • FIG. 3 represents a basic 4-wire configuration of the type used in the prior art
  • FIG. 4 depicts a typical a short circuit configuration used in the prior art
  • FIG. 5 is a prior art time constant configuration circuit
  • FIG. 6 is a general form of a proposed circuit which is according to the principles of this invention.
  • FIG. 7 is a general form of a proposed circuit with connector, wire, and capacitor impedance values denoted before and after both the sensing impedance and the battery impedances;
  • FIG. 8 represents a magnetic interface for sensing current I s according to the principles of this invention.
  • FIG. 9 is an alternative series embodiment of a proposed circuit according to the principles of this invention.
  • FIG. 10 is an electrical schematic of a prototype circuit implementing the invention concept
  • FIG. 11 is a graphical representation of impedance of a nickel cadmium battery during discharge.
  • FIG. 6 depicts a general form of a circuit which may be used to calculate a battery's impedance according to the proposed technique.
  • the circuit has the general construction of a current divider network.
  • C represents the capacitance of a DC-blocking capacitor 51 that is selected large enough for the AC range of interest. Selection of an appropriate size of capacitor
  • Z s is the magnitude of this impedance and does not include its phase angle. Without the DC-blocking capacitor 51, current from the battery 48 would drain into the sensing impedance Z s . Ideally, Z s is kept as close as possible to the anticipated impedance of the battery to be measured.
  • Zb represents the battery impedance that is being measured by the circuit, I; represents the input current signal and L. represents the sensing impedance current. Additionally, lb represents the AC current through the battery 48, though the actual current in the cell may contain a DC component if a load is connected to the battery 48.
  • current Ij travels from a current source 53 through a current signal path 50 to a current dividing connector 52 where it splits into portion I s , flowing through sensing current path 54, and into portion lb, flowing through battery current path 56.
  • the sensing current and battery current paths 54 and 56 eventually re-converge at current converging connector 58. If measurements are done online, the AC current signal can be choked with an appropriate AC choke 60, if necessary, so the load impedance, Z is much larger than Z s and Zb.
  • the circuit must be remodeled to include these additional impedance elements.
  • Each of these particular elements is included in FIG. 7, with the load being omitted.
  • the impedance resulting from capacitance C of DC-blocking capacitor 51 is lumped with the impedance of the connector and local segment of the battery current path 56 as Z4.
  • Zl, Z2, and Z3 represent the connector and wire impedances of sensing element 62 and battery 48.
  • Z s is a known value, and as noted above, is ideally kept as close as possible to the impedance of the battery to be measured. However, unlike Z s , the values of Zl, Z2, Z3, and Z4 are not known explicitly. For this circuit, it is known that
  • I s (Z 1 +Z s +Z 3 ) I b (Z 2 +Z b +Z 4 ) .
  • I' is known and measured.
  • Zx and Zy are not precisely known, and may not be known at all.
  • Z b is the value that must be determined.
  • the values of Z and Zy can be determined experimentally using two different calibrated impedances, Z ca ⁇ and Z ca ⁇ 2 .
  • the example procedure involves removing the battery 48 from the circuit and replacing it with Z cal ⁇ first and then Z ca i2. It will be appreciated, however, that removal of the battery 48 may not always be necessary in order to complete the required measurements according to the invention, for example if the values of Zl, Z2, Z3 and Z4 are small in relation to Zb and Z s , or if the values of Zl, Z2, Z3 and Z4 are already known.
  • a measurement of I s is made for each of the two calibrated impedances Z ca ⁇ and Z ca ⁇ . This results in two equations derived from the previous equation for Zb,
  • ZoaiN — INZ X + Z y which, depending on the range of the calibration impedances, can be solved linearly, piecewise- linearly, or nonlinearly for Z x and Z y . It should be noted that, unlike the prior art techniques discussed above, the voltage drops across Z s and Zb are never measured directly. Once the circuit is calibrated for Z x and Z y , the battery 48 can be placed back into the circuit for the determination of Z b from the measurement of I s .
  • I s is accomplished by magnetically coupling I s with a magnetic field sensor 64 such as a Hall effect or a magnetoresistive sensor or any other device which can determine the magnitude and phase of a magnetic field.
  • a magnetic field sensor 64 such as a Hall effect or a magnetoresistive sensor or any other device which can determine the magnitude and phase of a magnetic field.
  • Z s is an electrical conductor such as copper.
  • An appropriate magnetic interface 66 is depicted in FIG. 8. The figure shows how the magnetic interface links the sensing current, I s to the magnetic sensor 64.
  • the interface includes a ferromagnetic core 68 which is coupled to the magnetic field sensor 64 and which need not be wound.
  • the sensing current I s travels along the sensing impedance Z s throughout the ferromagnetic core 68 resulting in a magnetic flux 70.
  • the size and shape of the conductor Z s should be selected to maximize sensitivity of the current change when the battery impedance Zb changes and maximizes the flux linkage to
  • Zs represents a single turn winding on the magnetic core 68 and the magnetic sensor 64 sits in the air gap that dissects the core path.
  • the magnetic flux density that the magnetic field sensor 64 is exposed to is given by the equation
  • ⁇ core is the core permeability factor and ⁇ 0 is the permeability of
  • magnetic field sensor 64 must include considerations such as the sensor's ability for mounting in the core path and the ability to provide sufficient sensitivity to detect the sensing current I s .
  • Some suitable types that have been successfully implemented include Hall effect and anisotopic magnetoresistive (AMR) sensors which are readily available.
  • AMR sensors such as the Honeywell HMCIOOI, have demonstrated greater levels of sensitivity than Hall effect sensors, such as the Optek OHN-xx, for operation in small magnetic fields.
  • AMR sensors also offer a much wider bandwidth at approximately the same cost as Hall effect sensors.
  • Other alternative sensor types may present problems due to cost, bandwidth, and size.
  • Advantages of the invention over previous impedance measuring techniques include greater sensitivity and greater immunity to noise and EMI.
  • sensitivity is controlled mainly by the selection of the sensing impedance and the gap size of the core 68.
  • the fact that no potential measurements are taken across low voltage and impedance sources results in greater immunity to noise and EMI.
  • Most previous methods require that measurements of voltage drops be made across the battery 48 and/or sensing impedance. In comparison, the proposed technique requires only that a current measurement be made.
  • a further advantage of the invention relates to inherent noise and EMI limitations of previous techniques, such as the 4-wire circuit.
  • sensing amplifiers are required to amplify signals in the range of millivolts from a low impedance source, the battery, or sensing impedance.
  • Such amplification typically requires the use of transistor amplifiers, such devices being highly susceptible to electric field noise sources when the input source impedance is low.
  • the DC-blocking capacitor 61 is positioned in series between the battery impedance Zb and sensing impedance Z s . According to the proposed technique, an impedance measurement of the battery 48 would be accomplished first by noting that
  • V Is (Z b + Zs) and Zb - Vi - LZ S
  • implementation of this circuit embodiment requires knowledge of the source voltage V, sensing impedance Z s , as well as measurement of the sensing current I s .
  • this configuration is capable of making impedance measurements that are similar to other embodiments of the invention.
  • this specific configuration of the proposed circuit requires the inclusion of a voltage source V; which must maintain potential magnitudes on the order of millivolts.
  • this embodiment requires that for progressively larger battery cells, the voltage source Vi must become progressively smaller in order to maintain operability. Regulation of the voltage source Vi may become increasingly difficult for smaller battery impedances without an increase in the level of current delivered.
  • FIG. 10 is a schematic illustration of an example prototype circuit 72 incorporating the invention that can be used to collect battery impedance data from lead acid, nickel cadmium and lithium battery cells.
  • the circuit 72 is designed to be used with a PC based data acquisition (DAQ) board.
  • the DAQ board is used to inject a waveform (V DA Q) into the circuit at input 71 and toggle the set/reset circuit 82 of the AMR sensor with a signal (V S/ ) at input 73.
  • V IN J feed current
  • V SENS sensor response signal
  • the circuit section 74 in the upper left dashed box 75 represents the current source 76 and current divider circuit 78.
  • This section drives the current into the battery 79 and sensing element 81.
  • the injected waveform V DA Q is passed to the signal amplifier Ul which in turn generates the current I;.
  • the differential amplifier U2 is used to detect and to determine the value of Ii as it exists at the negative node of resistor R8 and enters the current signal path 50.
  • a ferromagnetic core XI of the magnetic sensor detects the value of I s at the sensing impedance 81.
  • the circuit section 80 in the upper right dashed box 83 represents the current sensing circuit that is linked to the sensing element via the ferromagnetic core XI and the magnetic sensor SI.
  • the combined resistances of component resistors 85 change in proportion to the magnetic field they encounter at the sensing impedance 81, with SI essentially comprising the ferromagnetic core XI.
  • a degaussing resistor 86 comprises a coil used for demagnetizing the component resistors 85 of the ferromagnetic core XI. In the event that an external magnetic signal interferes with the core's operation, the interference (magnetic offset) can be minimized by passing a positive voltage through the degaussing resistor 86 proximate to the component resistors 85.
  • the circuit section of the bottom dashed box 82 of FIG. 10 shows the set/reset circuit used for minimizing the magnetic offset in the magnetic sensor.
  • a signal V S/R at input 73 is electrically isolated from the rest of the circuit by an optical coupling U5.
  • the signal V S/R which is normally on the order of +5V, is manually dropped to 0V for a duration of, for example, one second.
  • the optical coupling U5 electrically isolates the signal V S/ R from the rest of the circuit, U5 still permits a mimicking +5V signal to pass from mimicking potential 88 through resistor R9 in response to each positive (+5V) condition for V S/R .
  • Mimicked signals are fed through four digital inverters U3, all of which may be contained on a single electronic chip allowing the signal to pass to a complementary MOSFET pair Q2.
  • the MOSFET pair Q2 includes an N-channel MOSFET 90 and an E-channel MOSFET 92, the pair functioning together as a combination toggle switch for effecting positive voltage through resistor 86. All four digital inverters act in concert to alternate the positive conditions of the N- and E-channel MOSFETS in order to toggle positive voltage through the degaussing resistor 86 depending on whether V S/ R is currently in its positive +5V condition. Minimizing the magnetic offset in this way insures that the magnetic sensor does not saturate or drift from the zero field point, helping to maintain high sensor resolution. This further enables the circuit to be used to collect impedance data on batteries while charging and discharging.
  • FIG. 11 is a sample plot of the impedance measured for a D-size, 4.3-Ahr nickel cadmium cell during discharge. Each point in the plot represents the cell impedance Zb at different frequencies ranging from 1 Hz at the upper right end of the curve to 17.7kHz at the lower left end of the curve. The data for this plot was obtained using the prototype circuit of FIG. 10 on a nickel cadmium cell during a discharge cycle. It will be appreciated that those skilled in the art will normally test a particular battery at one or more frequencies to determine the battery's impedance Z b at each frequency.

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  • General Physics & Mathematics (AREA)
  • Measurement Of Resistance Or Impedance (AREA)

Abstract

Selon l'invention, on mesure l'impédance d'une batterie par une technique utilisant normalement un réseau de diviseurs de courant connecté à la batterie. Le circuit utilisé dans cette technique comprend un générateur de courant (53), qui permet de produire un signal de courant régulé (Ii), ainsi qu'une ou plusieurs impédances sensibles (Zs) qui sont normalement disposées électriquement en parallèle, ou, dans d'autres réalisations, en série avec la batterie. Un condensateur bloquant l'écoulement de courant continu empêche une décharge de la tension de batterie dans la ou les impédances sensibles (Zs). Un capteur de champ magnétique, ou un dispositif équivalent, permet de mesurer la grandeur et/ou la phase du courant passant dans les impédances sensibles. La substitution d'un nombre d'impédances étalonnées dans le circuit à la place de la batterie permet un calcul mathématique initial de l'impédance de batterie en utilisant cette technique. Après quoi, on peut calculer des impédances de batteries en fonction du courant sans utiliser des impédances étalonnées.
PCT/US2000/035044 2000-01-03 2000-12-22 Procede et appareil destines a mesurer les impedances de cellule et de batterie electrochimiques WO2001050119A1 (fr)

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US17423400P 2000-01-03 2000-01-03
US60/174,234 2000-01-03

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
DE10345057A1 (de) * 2003-09-26 2005-04-28 Rwth Aachen Verfahren und Vorrichtung zur Bestimmung des Ladezustandes einer Batterie
DE102009009954A1 (de) * 2009-02-23 2010-08-26 Volkswagen Ag Verfahren und Vorrichtung zur Ermittlung des Ladungszustandes einer Batterie
CN114200309A (zh) * 2021-12-08 2022-03-18 广州小鹏汽车科技有限公司 车辆电池的仿真测试方法、装置、车辆以及存储介质
CN116953545A (zh) * 2023-09-21 2023-10-27 武汉理工大学 一种大功率燃料电池电堆交流阻抗检测系统及其方法

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US3582774A (en) * 1969-03-13 1971-06-01 Ford Motor Co Circuit impedance measuring device employing clamp on magnetic current sensor
US5483165A (en) * 1994-01-14 1996-01-09 Heartstream, Inc. Battery system and method for determining a battery condition
US6002238A (en) * 1998-09-11 1999-12-14 Champlin; Keith S. Method and apparatus for measuring complex impedance of cells and batteries

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US3582774A (en) * 1969-03-13 1971-06-01 Ford Motor Co Circuit impedance measuring device employing clamp on magnetic current sensor
US5483165A (en) * 1994-01-14 1996-01-09 Heartstream, Inc. Battery system and method for determining a battery condition
US6002238A (en) * 1998-09-11 1999-12-14 Champlin; Keith S. Method and apparatus for measuring complex impedance of cells and batteries
US6172483B1 (en) * 1998-09-11 2001-01-09 Keith S. Champlin Method and apparatus for measuring complex impedance of cells and batteries

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10345057A1 (de) * 2003-09-26 2005-04-28 Rwth Aachen Verfahren und Vorrichtung zur Bestimmung des Ladezustandes einer Batterie
DE10345057B4 (de) * 2003-09-26 2005-09-15 Rheinisch-Westfälisch-Technische Hochschule Aachen Verfahren und Vorrichtung zur Bestimmung des Ladezustandes einer Batterie
US7541814B2 (en) 2003-09-26 2009-06-02 Rheinische Landschaftspflege Jakob Voets Ing. Grad. Gmbh & Co. Kg Method and device for determining the charge of a battery
DE102009009954A1 (de) * 2009-02-23 2010-08-26 Volkswagen Ag Verfahren und Vorrichtung zur Ermittlung des Ladungszustandes einer Batterie
DE102009009954B4 (de) * 2009-02-23 2021-03-11 Volkswagen Ag Verfahren und Vorrichtung zur Ermittlung des Ladungszustandes einer Batterie
CN114200309A (zh) * 2021-12-08 2022-03-18 广州小鹏汽车科技有限公司 车辆电池的仿真测试方法、装置、车辆以及存储介质
CN114200309B (zh) * 2021-12-08 2024-01-09 广州小鹏汽车科技有限公司 车辆电池的仿真测试方法、装置、车辆以及存储介质
CN116953545A (zh) * 2023-09-21 2023-10-27 武汉理工大学 一种大功率燃料电池电堆交流阻抗检测系统及其方法
CN116953545B (zh) * 2023-09-21 2024-02-27 武汉理工大学 一种大功率燃料电池电堆交流阻抗检测系统及其方法

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