Hybrid Battery Charger / Tester

Abstract

A hybrid battery charger test apparatus is described as a modification to a battery charger having a DC output stage, and a boost converter added to the DC output stage of the charger, the boost converter being configured to output pulses and / or continuous AC waves for testing a battery. The hybrid charger may be used to output pure AC test waves (e.g., sine waves for electrochemical impedance spectroscopy testing), to output pulses such as HPPC pulses, and / or to perform GITT or incremental charge tests. For example, determining battery parameters through diagnostic testing may be accomplished by combining the existing functionality of the battery charger with a test procedure involving currents much lower than those used during battery charging or returning battery energy to the grid.

Description

[0001] The present invention relates to a hybrid battery charger / tester and methods of using or making such a charger / tester.

[0002] background

[0003] The state of health (SoH) of a battery can be determined using battery testing equipment with accurate voltage and current measurements, for example using impedance spectrometry or by GITT. These techniques are useful where the state of charge of the battery to be tested is known. This is usually achieved by fully charging the battery and then discharging it to the required level at which the test can be performed. All of this is time-consuming and energy-consuming, as the test can take days to complete and, in the case of traction batteries, requires a large amount of energy to be transferred into or out of the battery.

[0004] Another option is to derive the state of health from the operational data of the battery in normal use, for example by techniques that record battery parameters during operation. In this approach, the actual load during operation is considered equivalent to the test "excitation" or stimulus, and the battery voltage measured during this operation is considered the associated "response" to the load. However, the "excitation" is not controlled according to the test protocol, and the "response" cannot always be measured by accurate instruments. In some cases, the load and the variations in this load may even make it impossible to obtain useful information about the SoH. Impedance spectroscopy methods are not possible in this case.

[0005] Unidirectional and bidirectional chargers are known. Unidirectional chargers are common for all sizes of batteries and cannot perform the full range of diagnostic tests because the current needs to flow in both directions during the test. Discharging would require discharge equipment (such as a discharge resistor, which would waste energy from the battery while it is discharged), require cooling and add additional weight. Bidirectional chargers are designed to be able to charge the battery and to be able to send power back from the battery to the grid. Therefore, the current ratings for charging will be the same as those used for discharging, which for automotive batteries are much higher than those used in diagnostic tests, so the low diagnostic test currents cannot be accurately measured. SUMMARY OF THE INVENTION

[0007] There is a need for a battery test (of a car battery, for example, used to drive a traction motor) that is not expensive and time consuming to perform and that is preferably more accurate than test values ​​recorded during use of operating data.

[0008] In one aspect, the present invention provides a hybrid battery charger test device comprising:

[0009] A battery charger with a DC output stage, and

[0010] A unidirectional or bidirectional boost converter added to the DC output stage of the charger is configured to output a current test sequence for testing the battery. This allows the car battery used to drive the traction motor to be tested in a simple manner.

[0011] The unidirectional or bidirectional boost converter can be adapted to output unidirectional or bidirectional pulses and / or continuous AC waves, respectively, for testing the battery. This allows a wide range of tests to be performed.

[0012] The unidirectional or bidirectional boost converter may be a retrofit boost converter and may be retrofitted to an existing charger. This provides a useful capacity increase to an existing charger without the need to purchase an entirely new device.

[0013] The unidirectional or bidirectional boost converter preferably has a dedicated current and / or voltage sensor whose full-scale range is adapted for testing the current or voltage to be applied to the battery.Instruments for operational control cannot achieve increased sensitivity.

[0014] Bypassing of the current and / or voltage sensors may be provided to avoid operating currents and voltages that damage the specialized equipment used in the present invention.

[0015] The unidirectional or bidirectional boost converter circuit has a controller for controlling the unidirectional or bidirectional pulse output and / or continuous AC wave for testing the battery, respectively. The controller may be adapted to communicate with the power electronics in the battery charger to output unidirectional charging pulses. This will reuse the charger for testing in an efficient manner.

[0016] The unidirectional or bidirectional boost converter preferably has one or more capacitors configured so that the boost converter can obtain a specified voltage and the one or more capacitors can obtain a specified capacitance. This provides the boost converter with the ability to generate a voltage high enough to charge the battery. At the same time, the current can be absorbed in the capacitor during discharge, so no energy is lost or a current sink like a resistive heater is required.

[0017] A unidirectional or bidirectional boost converter can be adapted to perform any, some or all of GITT testing, HPPC testing, impedance spectroscopy testing, incremental charge testing, pulse testing. This provides a wide range of testing possibilities.

[0018] The unidirectional or bidirectional boost converter has storage for storing test results of diagnostic tests performed on the battery.Data acquisition can be used to confirm or refine the model of the battery.

[0019] In another aspect, the present invention provides a retrofit unidirectional or bidirectional boost converter circuit for retrofitting to a battery charger, comprising:

[0020] Connections for coupling a retrofitted unidirectional or bidirectional boost converter circuit to a DC output stage of a battery charger, the retrofitted unidirectional or bidirectional boost converter circuit being configured to output a current test sequence for testing a battery.

[0021] A hybrid battery charger test device is described as a modification to a battery charger having a DC output stage, and a boost converter added to the DC output stage of the charger, the boost converter being configured to output pulsed and / or continuous AC waves for testing a battery.

[0022] The hybrid charger may be used to output a pure AC test wave (e.g., a sine wave for electrochemical impedance spectroscopy testing), to output pulses such as HPPC pulses, and / or to perform GITT or incremental charge tests. For example, determining battery parameters through diagnostic testing may be accomplished by combining the existing functionality of the battery charger with a test procedure that involves currents much lower than those used during battery charging or returning battery energy to the grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A hybrid charger / tester according to one embodiment of the present invention is shown.

[0025] Figure 2 A hybrid charger / tester with a voltage boost circuit according to one embodiment of the present invention is shown.

[0026] Figure 3 A hybrid charger / tester with a voltage boost circuit according to a further embodiment of the present invention is shown.

[0027] Figure 4 Pulses typically applied during HPPC testing are shown.

[0028] Figure 5 The response of the battery to the pulse test is shown.

[0029] Figure 6 The charge and discharge curves of the battery during the incremental charge test are shown.

[0030] definition

[0031] SOC: State of Charge

[0032] SOH: State of Health

[0033] EV: Electric Vehicle

[0034] GITT: Galvanostatic Intermittent Titration Technique

[0035] HPPC: Hybrid Pulse Power Characterization

[0036] EIS: Electrochemical Impedance Spectroscopy

[0037] "Retrofitting" or "retrofitting" refers to adding new technology or features to an older system (i.e., a system that includes legacy equipment). Legacy equipment can be identified by its installation date or based on other records. Retrofitted equipment can be identified by its installation date or based on other records. DETAILED DESCRIPTION

[0038] The present invention will be described with respect to specific embodiments and with reference to certain drawings, but the invention is not limited thereto but only by the claims. The drawings described are schematic and non-limiting only. In the drawings, the dimensions of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and relative dimensions do not correspond to actual reductions to the implementation of the invention.

[0039] In addition, the terms first, second, third, etc. in the specification and claims are used to distinguish between similar elements and not necessarily to describe a sequential or chronological order. It should be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operating in other sequences than described or illustrated herein.

[0040] It should be noted that the term "comprising" used in the claims should not be interpreted as being limited to the means listed thereafter; it does not exclude other elements or steps. Therefore, the term should be interpreted as specifying the presence of the stated features, integers, steps or components as mentioned, but does not exclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Therefore, the scope of the expression "a device comprising means "A and B" should not be limited to devices consisting only of components A and B. This means that for the present invention, the only relevant components of the device are A and B.

[0041] refer to Figure 1 , one aspect of the present invention is a dedicated battery charger 11, which is also adapted to act as test equipment 12. Such a hybrid charger / tester 10 according to various embodiments of the present invention may be on-board or off-board. Whether on-board or off-board, when connected to the battery 14 (i.e. at the DC level), the hybrid charger / tester 10 according to various embodiments of the present invention may have, for example, power electronics 16 to regulate the current supplied to the battery, as well as the voltage of the battery 14. A preferred form of the charger / tester 10 is a charger, such as a fast charger for charging a car battery used to drive the traction motor of an electric vehicle.

[0042] The hybrid battery charger / tester 10 according to various embodiments of the present invention is a dedicated battery charger that is also adapted to serve as a test rig. Once the battery 14 is connected to the charger / tester 10, a test may be performed to determine the state of charge (SoC) of the battery 14, or to collect test results from which the SoC of the battery or other parameters of the battery may be estimated. The execution of the test and the recording of the results (data acquisition) may be performed by a suitable processing engine 18 (such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP, or an ASIC) in combination with a suitable memory 19 (e.g., a random access memory (RAM) and / or a non-volatile memory). The test rig 12 of the hybrid battery / tester 10 according to various embodiments of the present invention may be configured to perform known methods for determining or estimating SoC. For example, the known methods may be controlled by a processing engine 18 (such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP, or an ASIC). For example, the hybrid charger / tester 10 according to various embodiments of the present invention may communicate with a battery management system (BMS 30), from which the initial SoC may be determined. Communication may be performed between the processing engine 18 and the BMS 30 by means of a communication interface (e.g., via a wired or wireless interface), wherein the BMS 30 and the hybrid charger / tester 10 may be part of a CAN. The BMS 30 and / or the battery charger / tester 10 may be configured to modify the SoC of the battery by partially charging the battery 14. Thereafter, a test cycle may be initiated using the tester 12 (e.g., controlled by the BMS 30 and / or the battery charger / tester 10), for example, similar or identical to a phase of a proprietary or known battery health diagnostic test (such as an HPPC test). The full HPPC may be performed using bidirectional pulses or may only apply unidirectional pulses. In many cases, such testing only requires being at an intermediate SoC level (e.g., not 0 or 100%, but at an intermediate value such as 70%). For example, one advantage of such testing may be that the values ​​of the test results of the components in the electrical equivalent model of the battery are derived, and preferably accurately obtained. The current 36 has a full scale range, which is adapted to accurately measure currents below the operating charging current and thereby give a more accurate value. The voltage sensor 34 may also have a sensitivity adapted to smaller voltage changes during testing. A processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP or an ASIC may be configured to derive the values ​​of the components in the equivalent model of the battery from historical voltage and current measurements. These parameters are preferably stored in a database 20, and the test results over a period of time may be recorded in the database 20. This database 20 may be stored as part of the memory 19, or may be stored remotely (e.g., remotely stored on a server on a local or remote network). Long-term evolution may be traced back from the stored historical test results.This access to the long term evolution may allow for precise or more precise state of health (SoH) estimates. A processing engine 18 such as a microcontroller, microprocessor with dedicated software, FPGA, ASIP or ASIC may be configured to determine the long term evolution and calculation of precise or more precise state of health (SoH) estimates.

[0043] For example, the time required for one HPPC test phase is limited to a few minutes, so the impact on the charging time is limited. HPPC testing is typically performed by applying charge and discharge pulses. Since it is typically not possible or permitted to discharge the battery using the charger 11, one aspect of the present invention is to provide a hybrid charger / tester 10 that is capable of applying current in either or both directions to the battery. A processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP, or an ASIC can be configured to control the application of current in either direction to the battery, for example, also to apply pulses in either direction. This is an advantage because a test method using pulses applied only on the charging side would initially generate values ​​of unknown correlation prior to validating the method.

[0044] In various embodiments of the hybrid charger / tester 10 according to the present invention, the power electronics of the charger 11 or the tester 12 can be used to inject AC current into or extract AC current from the battery 14 as required by the impedance spectroscopy method. The various embodiments of the hybrid charger / tester 10 according to the present invention do not need to measure the complete spectrum, and this reduced number of test frequencies has the advantage of reduced test time. Preferably, the various embodiments of the charger / tester 10 according to the present invention preferably test only at the frequencies of interest. The processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP or an ASIC can be configured to control the testing at multiple frequencies or a single frequency. In particular, the various embodiments of the hybrid charger / tester 10 according to the present invention test at frequencies that produce a phase shift close to zero. These test frequencies can be of the order of 1 kHz. This is advantageous because the test at lower frequencies is not used. Testing at <1 kHz requires longer test time. In the case where the battery charger does not allow discharge, a small AC current can be superimposed on a small DC current so that the total current never reverses.

[0045] Embodiments of the hybrid charger / tester 10 according to the present invention may perform diagnostic tests such as differential charge measurement, HPPC or GITT, for example, under the control of a processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP or an ASIC. This produces information about the battery chemistry and life, but it is time consuming. According to embodiments of the charger / tester 10 according to the present invention, these tests are performed if there is enough time. This can be indicated by input of a user action, which the user uses to indicate that a suitable time period is available, for example, an input indicating that the car will not be used for a specific time period (such as the next two days). The hybrid charger / tester 10 of embodiments of the present invention may have a user input device 26, for example, coupled to an I / O port of a processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP or an ASIC.

[0046] Another alternative is that the processing engine 18 such as a microcontroller, microprocessor with dedicated software, FPGA, ASIP or ASIC can be configured to combine the DC charging process with other diagnostic tests such as HPPC current pulse or small AC current test. The charger current is then a superposition of the DC current required for charging and the AC current required for impedance spectroscopy. The loss of charging time is limited.

[0047] The hybrid charger / tester 10 according to various embodiments of the present invention is different from a conventional unidirectional charger, a conventional bidirectional charger or a conventional tester in at least one, at least some or all of the following features:

[0048] 1. It can adjust the current and voltage according to different algorithms for testing, charging or discharging instead of simple (fast) charging. For example, a processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP or an ASIC can be configured to execute these algorithms.

[0049] 2. It enables more accurate measurements. For example, a processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP, or an ASIC can be configured to make more accurate measurements by using signals from the voltage sensor 34 and the current sensor 36, whose full-scale range and accuracy are adapted to the test voltage and current.

[0050] 3. It optionally uses a battery model for each relevant battery type. Optionally, a processing engine 18 such as a microcontroller, microprocessor with dedicated software, FPGA, ASIP or ASIC can be configured to store such battery models in a memory 19.

[0051] 4. It can calibrate a single battery to a selected model. For example, a processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP, or an ASIC can be configured to calibrate the battery 14 to a selected model.

[0052] 5. It can store the battery data in a database 20. This database 20 can be local, such as stored in the memory 19, or stored at a remote location, such as the cloud. Embodiments of the hybrid charger / tester 10 according to the present invention can be provided with a communication port and appropriate communication capabilities to communicate with a remote database. For example, a processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP or an ASIC can be configured to perform such communications.

[0053] 6. Various embodiments of the hybrid charger / tester 10 according to the present invention may be provided with sufficient non-volatile memory 19 to store historical measurement results of the tester / charger 10 , which may be downloaded to the database 20 from time to time.

[0054] 7. Embodiments of the hybrid charger / tester according to the present invention may determine SoH by a method based not only on battery operating data, but may include, for example, the use of predetermined stimulus / response. For example, a processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP, or an ASIC may be configured to determine SoH by a method based not only on battery operating data, but may include, for example, measurements from predetermined stimulus / response.

[0055] 8. Embodiments of the hybrid charger / tester 10 according to the present invention can determine the SoH without requiring separate dedicated test equipment that must be applied in a separate procedure initiated by a technician or without requiring time-consuming testing. A processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP, or an ASIC can be configured to determine the SoH using the test equipment 12.

[0056] Embodiments of the present invention utilize a battery charger 11 for an automobile as part of a hybrid charger / tester 10 by adding a unidirectional or bidirectional current testing device 12. There are two main types of chargers for charging batteries for electric vehicles:

[0057] • A charger for charging the car's starter battery, which is conventional and may typically be a multi-stage charger, such as a 3-stage charger for use with embodiments of the present invention.

[0058] • A charger for charging an electric vehicle (EV) battery pack for a traction motor used with embodiments of the present invention. A hybrid charger / tester according to embodiments of the present invention can use either single-phase or three-phase AC input.

[0059] Electric vehicle battery chargers are already available from companies such as Zivan, Manzanita Micro, Elcon, Quick Charge, Rossco, Brusa, Delta-Q, Kelly, Lester, and Soneil. The maximum charging power of such chargers can vary from 1 kW to 7.5 kW. There are various known charging protocols, any of which can be used with embodiments of the present invention, such as charging using a charging curve, or constant voltage, constant current, etc.

[0060] Embodiments of the present invention may be used in public EV charging stations (eg, having a power rating of 6 kW).

[0061] Rapid charging used with embodiments of the present invention results in faster charging times and is limited only by the available AC power source, battery type, and charging system type.

[0062] The on-board EV charger used with embodiments of the present invention changes AC power to DC power for charging the EV battery pack and may be:

[0063] Isolated, where there is no physical connection between the A / C grid and the battery being charged. These typically employ some form of inductive charging. Some isolated chargers can be used in parallel. This allows for increased charging current and reduced charging time. Typically, EV batteries have a maximum current rating that cannot be exceeded.

[0064] Non-isolated: The battery charger has a direct electrical connection to the A / C outlet wiring. Non-isolated chargers cannot be used in parallel.

[0065] An off-board or on-board hybrid charger / tester 10 according to any embodiment of the present invention may have an AC input side 28 and a DC output side 29 for charging purposes, such as Figure 1. For example, an off-board or on-board hybrid charger / tester 10 may include a converter that converts an AC voltage of an input AC source 32 (such as from a power grid) to a boosted DC voltage (optionally higher than the AC voltage amplitude). The AC side 28 may include one or more power factor converters (PFCs). A subsequent DC-DC converter may generate a high-frequency AC voltage that is rectified at the secondary of the isolation transformer to generate a DC charging output. The hybrid charger / tester 10 according to various embodiments of the present invention may also include a voltage sensor 34 and / or a current sensor 36.

[0066] As another example, the AC side of the hybrid charger / tester 10 according to various embodiments of the present invention may be a rectifier with one or more PFC boost converters. The subsequent DC-DC converter may be an isolated full-bridge DC-DC converter.

[0067] The PFC boost converter may include an interleaved PFC including two CCM boost converters in parallel that operate 180° out of phase. Since the ripple currents are out of phase in such an arrangement, they tend to cancel each other and reduce the input ripple current. Interleaving reduces the output ripple current as a function of the duty cycle. Interleaved boost converters inherently utilize parallel semiconductors to reduce conduction losses. In addition, by switching the converters out of phase, the effective switching frequency is doubled, thereby reducing the input current ripple, thereby reducing the size of the input EMI filter. The interleaved PFC boost converters each operate at half the rated power of the load. A full-bridge zero voltage switching (ZVS) converter with an output rectifier may be provided.

[0068] Similar topologies can be found in fast chargers for electric vehicles. For example, the output can be a buck converter for controlling the voltage level at the output. There can be two buck converters, one for the positive voltage cycle and another for the negative voltage cycle.

[0069] Embodiments of the present invention provide a hybrid charger / tester 10 that includes any known unidirectional charger (such as any of the designs mentioned above), wherein the DC output, rectifier or DC-DC converter (e.g., a buck converter at the output of the charger) does not allow negative current, i.e., the charger is unidirectional, and the charger 11 applies current in only one direction. The tester 12 according to embodiments of the present invention can provide pulses of polarity and / or pure AC current, such as sine wave, triangle wave or square wave output.

[0070] For example, in order to enable the tester function, in various embodiments of the present invention, a bidirectional boost converter 40 is added to the output of the charger 11, such as Figure 2 and Figure 3The boost converter 40 may use the same inductor 42 and capacitor 44 as the LC filter 46 (as already available at a typical conventional output of the charger 11 or similar conditions), so that when the converter 40 is active, the charger or fast charger does not deliver any current that would otherwise not be purely sinusoidal.

[0071] The converter 40 only needs to deliver a current of about 1 amp AC RMS to produce a measurable voltage ripple in the battery 14. Most car batteries have a resistance higher than 0.1 ohms, so a 1A current will produce a 0.1V voltage drop, which can be accurately measured by a voltage sensor 34 across the battery, but cannot usually be measured by a voltmeter on a charger adapted to measure 300-400V. The voltage sensor 34 has a full-scale range suitable for the generated test voltage. A current sensor 36 is also provided, which also has a full-scale range suitable for measuring lower currents during testing than during operation. The maximum voltage of most car batteries is about 300-400V, so in most cases, two diodes 52 and 54 such as two 600V / 1A MOSFETs and two semiconductor switches 57 and 59 (wherein diodes 52 and 54 are connected in parallel) are sufficient to form the converter 40. At higher voltages, 1200V / 1A IGBTs can be used. If the existing LC filter 46 from the charger 11 is reused, no additional filter needs to be added, however if the LC filter 46 is not present, a small 1A inductor can be added. A processing engine 18 such as a microcontroller, microprocessor with dedicated software, FPGA, ASIP or ASIC can be configured to control the converter 40 to apply such current by controlling switches 56, 57 and 59.

[0072] If a 400V battery is to be tested with a 1A current at 1kHz, the energy included in each half cycle is 400VRMS*1ARMS*0.5ms=200mJ. If the voltage at the input side of the boost converter is limited to, for example, between 500 and 520V, a 20mF capacitor can be used. This is a feasible solution and can be achieved by configuring one or more capacitors 43, 45, 47, 49 (such as four 12mf / 450V capacitors) together with one or more capacitors such as two capacitors in series (to obtain the required voltage) and one or more capacitors such as two capacitors in parallel (to obtain the required capacitance).

[0073] Another embodiment of the boost converter 40 is as follows: Figure 3 shown. Figure 2 All components and functions of the boost converter 40 shown in FIG. Figure 3All are available in the illustrated embodiments, such as using the same inductor 42 and capacitor 44 as the LC filter 46 (already available in the typical conventional output of the charger 11), a voltage sensor 34 across the battery (usually not measurable by a voltmeter on the charger adapted to measure 300-400V). The voltage sensor 34 has a full-scale range suitable for the generated test voltage. A current sensor 36 is also provided, which also has a full-scale range suitable for measuring lower currents during testing than during operation. In addition, a current sensor bypass is also provided, for example, by switch 62, which is controlled by a processing engine 18 (such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP or an ASIC). If the LC filter 46 is not present, a small 1A inductor can be added. A processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP or an ASIC can be configured to control the boost converter 40 current by controlling switches 57 and 59 (where diodes 52 and 54 are connected in parallel) and switch 56. The processing engine 18, such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP or an ASIC, is also configured to communicate with the power electronics of the charger via connection 64. The processing engine 18, such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP or an ASIC, is also configured to communicate with a remote database 26. One or more capacitors, such as four capacitors 43, 45, 47, 49, may also be provided, configured with one or more capacitors, such as two capacitors in series, to obtain the required voltage, and with one or more capacitors, such as two capacitors in parallel, to obtain the required capacitance.

[0074] In the case of hybrid pulse power characterization (HPPC test), an additional boost converter 40 applies 10 second discharge and charge pulses to the battery at different SoCs of the battery 14. A processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP or an ASIC can be configured to control the converter 40 to apply unidirectional or bidirectional (e.g., discharge and / or charge) pulses. For the charge pulse, the conventional output of the charger 11 can be used. The available charging power can be derived from the voltage response and current measured during the charge pulse. The voltage response and current during the charge pulse can be measured by the voltage and current sensors 34 and 36, respectively. For the discharge pulse, it cannot be provided by the charger 11 because ordinary fast chargers are unidirectional devices that cannot apply discharge pulses. Bidirectional chargers for automotive batteries that drive traction motors do not have current control that can apply such pulses. If this 10 second discharge pulse is to be applied, a switch resistor such as a switch resistor 56 can be added to the output of the charger 11, which allows the 10 second discharge pulse to be drawn. Since the pulse is applied for only 10 seconds, the switch and resistor can handle the significant transient temperature rise, minimizing the need for cooling of both. This switch resistor is added to the charger output. The available discharge power can also be derived from the voltage response and current measured during the discharge pulse.

[0075] The HPPC test is intended to determine the dynamic power capability of the device within the available voltage range using a test curve that combines both discharge and regeneration pulses. A processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP, or an ASIC can be configured to control the converter 40 by controlling switches 56, 57, and 59 to perform the HPPC test and to measure voltage and current changes using voltage sensors 34 and current sensors 36. The first step in this test is to establish the Vmin0 discharge power capability at the end of (a) a 10s discharge current pulse and the Vmaxop regeneration power capability at the end of (b) a 10s regeneration current pulse as a function of the capacity or available energy removed. These power and energy capabilities are then used to derive other performance characteristics, such as charge maintenance available energy and available power and charge consumption available energy, in order to directly compare with the target values ​​of these parameters. A processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP, or an ASIC can be configured to perform the derivation and comparison of these parameters.

[0076] For example, additional data from the HPPC test includes voltage response curves, which can be measured and stored, and if desired, transmitted to a remote device by a processing engine 18 (such as a microcontroller, microprocessor with dedicated software, FPGA, ASIP or ASIC), from which the fixed (ohmic) battery resistance and battery polarization resistance as a function of removed capacity can be determined, assuming sufficient resolution to reliably establish the battery voltage response time constant during discharge, rest and regeneration operating regimes. This resolution is provided by the voltage sensor 34 and the current sensor 36. These data can be used to assess resistance degradation during subsequent life testing and to develop hybrid battery performance models for automotive system analysis.

[0077] Electrochemical impedance spectroscopy (EIS) is an effective method for obtaining information about electrochemical systems such as batteries. It is applied to batteries, fuel cells, and super or ultra capacitors. EIS can be used in all stages of new device development, from initial evaluation of half-cell reaction mechanisms and kinetics to quality control of packaged batteries. The development of batteries for higher power applications such as electric vehicles has led to the development of devices with very low impedance. The impedance of modern batteries is usually so low that it cannot be easily or accurately measured using conventional systems on commercial chargers. The various embodiments of the present invention solve this problem by providing a boost converter 40. In the case of electrochemical impedance spectroscopy testing, an additional boost converter 40 with a small storage capacity is sufficient to excite the battery with a 1A current, ranging from less than 1kHz to the bandwidth of the added small converter (which can be tens of kHz in the case of using MOSFETS or GaN switches). This allows EIS testing to be performed at a specified frequency range. In addition, the full-scale range of the voltmeter 34 and the ammeter 36 included in the boost converter 40 is suitable for (i.e., has the required sensitivity) the voltage and current to be measured to allow accurate testing using EIS.

[0078] The GITT procedure consists of a series of current pulses, each followed by a relaxation time during which no current flows through the cell. A processing engine 18 such as a microcontroller, microprocessor with dedicated software, FPGA, ASIP or ASIC can be configured to control the converter 40 to perform the GITT test. The current is positive during charging and negative during discharging. During the positive current pulse, the cell potential increases rapidly to a value proportional to the drop in iR, where R is the uncompensated resistance Run (R 未补偿 ) and charge transfer resistance Rct(R 电荷转移). Afterwards, due to the constant current charging pulse, the potential increases slowly to maintain a constant concentration gradient. When the current pulse is interrupted (i.e. during the relaxation time), the composition in the electrode tends to become uniform, for example by diffusion of lithium ions in a lithium battery. Therefore, the potential first drops suddenly to a value proportional to the drop in iR, and then slowly decreases until the electrode is in equilibrium again (i.e., when dE / dt~0) and reaches the open circuit potential (Voc) of the battery. Then, a constant current pulse is applied again, after which the current is interrupted. The sequence of charging pulses followed by relaxation times is repeated until the battery is fully charged. During a negative current pulse, the opposite is true. The battery potential drops rapidly to a value proportional to iR. Then, the potential drops slowly due to a constant current discharge pulse. During the relaxation time, the potential suddenly increases by a value proportional to iR, and then slowly increases until the electrode is in equilibrium again (i.e., when dE / dt~0) and reaches the Voc of the battery. Then, a subsequent constant current pulse is applied, after which the current is interrupted. The sequence of a discharge pulse followed by a relaxation time is repeated until the battery is fully discharged. The chemical diffusion coefficient can be calculated at each step.

[0079] In the case of the incremental charge test, the battery is charged at a very slow rate, limited to C / 20, so charging a depleted battery will take at least 20 hours. During this test, the battery is charged at a constant current. During charging, the voltage will experience one or more voltage plateaus. A processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP, or an ASIC can be configured to control the converter 40 to perform the incremental charge test. Based on these results, the derivative of voltage and charge (dV / dq) can be plotted as a function of voltage (or SoC). This graph can be used to determine, for example, the SoH of the battery. A processing engine 18 such as a microcontroller, a microprocessor with dedicated software, an FPGA, an ASIP, or an ASIC can be configured to provide the derivative of voltage and charge (dv / dq) as a function of voltage (or SoC) and determine, for example, the SoH of the battery.

[0080] In the above case, a small inverter 40 or a switched resistor 56 with minimal storage capacity is included in the hybrid charger / tester 10 to perform the required tests in both current directions. According to various embodiments of the present invention, these additions transform a unidirectional charger 11 or a bidirectional charger that cannot apply a test negative current from the battery to the charger into a charger / tester 10.

[0081] Testing Procedure

[0082] Embodiments of the present invention may be used with two types of chargers:

[0083] 1. Those chargers with unidirectional current capability

[0084] 2. Those chargers that are inherently bidirectional and capable of delivering high discharge power

[0085] Bidirectional testing capability can be achieved by adding a low power boost circuit 40 to the charger 11. This can be done as a retrofit action. The boost circuit 40 can be a retrofit circuit. The test current is much lower than the charge or discharge current of the car battery, so an additional low power boost circuit 40 with voltage and current sensing devices 34, 36 is required that is accurate for the test voltage and current that are low compared to the operating current and voltage variations.

[0086] Embodiments of the present invention may be used with three types of State of Health SoH or State of Charge (SoC) test procedures:

[0087] 1. Impedance spectroscopy (EIS): This test can be performed in pure AC or DC+AC mode.

[0088] Information on the relationship between pure AC impedance and SoH can be obtained from the battery manufacturer or battery tester. DC+AC (AC is superimposed on the DC offset) impedance test requires verification. Embodiments of the present invention can provide full bidirectional charging and (ACEIS), so there is no need to use unverified tests unless otherwise required.

[0089] 2. HPPC or similar: This test requires multiple high power pulses to be input and output from the battery in order to calibrate the equivalent electrical model of the battery. Individual pulses can be used for this (e.g., charging pulses), more pulses provide more information and thus a more accurate model. Various embodiments of the present invention may provide charging pulses.

[0090] HPPC test Figure 4 As shown, this is a series of pulses in charge and discharge. This process allows the Figure 5 The voltage response of the current pulse shown in Figure 1 is used to calibrate the equivalent circuit. Figure 5 As can be seen from the diagram, both current directions contain similar information, so there is no need to provide pulses in both directions. Therefore, during charging, for example, the test can only be performed in one direction.

[0091] 3. Incremental charging: This method evaluates the form of the dq / dV curve while charging and discharging the battery at a low rate. The height and position of the peak in this curve can be related to the SoH of the battery. Figure 6As can be seen in Figure 1, the charge and discharge curves are similar to each other. The offset between them is largely determined by twice the voltage drop across the battery internal resistance caused by the C / 20 excitation current. One of the charge / discharge curves plus the knowledge of the battery internal resistance is sufficient for a SoH assessment. Furthermore, it is not always necessary to start with an empty battery and charge it to full charge in c / 20 (in 20 hours), as only the area around the peak is important.

[0092] Overview

[0093]

[0094] The above test procedures usually produce relevant information. As the battery ages, the test results vary over time, and it is preferred to store historical test results from which the aging can be observed. Reference values ​​are preferably obtained when the battery is new and SoH=100%. Measurements made in this case should be stored for future reference. Such results can be stored in a central database so that any charger, regardless of where the battery is charged, can access this data for reference and store the current situation. This allows accurate follow-up, preventive action when necessary, or even battery failure prediction in the future.

[0095] Control and data acquisition

[0096] Control options

[0097]

[0098]

[0099] Data collection options (e.g. using processing engine 18 and memory 19)

[0100]

[0101] The data sampled at a high rate and for a considerable period of time may result in a large amount of data. A processing engine 18, such as a microcontroller, microprocessor with dedicated software, FPGA, ASIP or ASIC, may be configured to run the SoH algorithm and store this data (either in memory 19 or to remote storage) in order to perform calculations on it, such as curve fitting.

[0102] A processing engine 18 such as a microcontroller, microprocessor with dedicated software, FPGA, ASIP or ASIC can be configured to determine the SoH of the battery processor (hardware or software function block). It only needs to know when the stimulus is applied. Because both the stimulus and the response are measured, no further connection to the power electronics controller in the charger 11 is required.

Claims

1. A hybrid battery charger test device comprising: A battery charger with a DC output stage, and A unidirectional or bidirectional boost converter added to the DC output stage of the charger, the unidirectional or bidirectional boost converter being configured to output a current test sequence for testing a battery, wherein the unidirectional or bidirectional boost converter has a dedicated current and / or voltage sensor, the full-scale range of the dedicated current and / or voltage sensor being adapted to test the current or voltage to be applied to the battery, wherein the unidirectional or bidirectional boost converter is adapted to output a continuous AC wave for testing the battery at a frequency that produces a near-zero phase shift.

2. The hybrid battery charger test device as claimed in claim 1, characterized in that The unidirectional or bidirectional boost converter is adapted to output unidirectional or bidirectional pulses, respectively, for testing the battery.

3. The hybrid battery charger testing device as claimed in claim 1, characterized in that: The hybrid battery charger test device is adapted to output an AC current superimposed on a DC current such that the total current never reverses.

4. The hybrid battery charger testing device according to claim 1 or 2, characterized in that: Further included is a bypass of the current and / or voltage sensor.

5. The hybrid battery charger testing device as claimed in claim 1, characterized in that: The unidirectional or bidirectional boost converter circuit has a controller for controlling the output of unidirectional or bidirectional pulses and / or a continuous AC wave, respectively, for testing a battery.

6. The hybrid battery charger testing device as claimed in claim 5, characterized in that: The controller is adapted to communicate with power electronics in the battery charger to output unidirectional charging pulses.

7. The hybrid battery charger testing device as claimed in claim 1, characterized in that: The unidirectional or bidirectional boost converter has one or more capacitors configured to enable the boost converter to reach a specified voltage.

8. The hybrid battery charger testing device as claimed in claim 1, characterized in that The unidirectional or bidirectional boost converter is adapted to perform any, some or all of GITT test, HPPC test, impedance spectroscopy test, incremental charge test, pulse test.

9. The hybrid battery charger testing device as claimed in claim 1, characterized in that: The unidirectional or bidirectional boost converter has storage for storing test results of diagnostic tests performed on the battery.

10. A retrofit unidirectional or bidirectional boost converter circuit for retrofitting to a battery charger, comprising: a connection for coupling the retrofitted unidirectional or bidirectional boost converter circuit to a DC output stage of the battery charger, the retrofitted unidirectional or bidirectional boost converter circuit being configured to output a current test sequence for testing a battery, wherein the retrofitted unidirectional or bidirectional boost converter circuit has a dedicated current and / or voltage sensor having a full-scale range adapted to test the current or voltage to be applied to the battery, wherein the retrofitted unidirectional or bidirectional boost converter circuit is adapted to output a continuous AC wave for testing the battery at a frequency that produces a near-zero phase shift.

11. The modified unidirectional or bidirectional boost converter circuit according to claim 10, characterized in that: The retrofitted unidirectional or bidirectional boost converter circuit is adapted to output unidirectional or bidirectional pulses, respectively, for testing a battery.

12. The modified unidirectional or bidirectional boost converter circuit according to claim 10 or 11, characterized in that: Further included is a bypass of the current and / or voltage sensor.

13. The modified unidirectional or bidirectional boost converter circuit according to claim 10, characterized in that: The retrofit unidirectional or bidirectional boost converter circuit has a controller for controlling the output of unidirectional or bidirectional pulses and / or continuous AC waves, respectively, for testing the battery.

14. The modified unidirectional or bidirectional boost converter circuit according to claim 10, characterized in that: The retrofitted unidirectional or bidirectional boost converter has one or more capacitors configured to enable the retrofitted unidirectional or bidirectional boost converter circuit to reach a specified voltage.

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