Secondary battery charging / discharging test device

Abstract

A charging and discharging test device 10 comprises: an AC converter 14 with an AC-side connection connected to a commercial AC power supply 12 and a DC-side connection connected to a common DC bus 13, and a plurality of bidirectional DC converters 15, one end of each of which is connected to the common DC bus 13 and the other end of each of which is connected to the test object 11 in which a plurality of secondary batteries are connected in series, a storage battery 16, an auxiliary power generation device 17 connected to the common DC bus 13, and a control unit 18 which controls each of the bidirectional DC converters 15.At the time of charging and discharging each test object 11, energy is transferred and received between each of the test objects 11 and the storage battery 16, and in case of an energy shortage in the storage battery 16, energy is supplemented by the auxiliary energy generation device 17.

Description

Technical area

[0001] The present invention relates to a charge / discharge test apparatus for secondary batteries, with which charge and discharge tests (life tests) on a plurality of secondary batteries, such as lithium-ion batteries, can be carried out jointly and efficiently with low power consumption. General state of the art

[0002] In recent years, the demand for secondary batteries (mainly lithium-ion batteries) has increased rapidly due to the development of IT devices such as smartphones and the practical implementation of electric vehicles and the like. In the final step of industrial mass production of such secondary batteries, activation and quality tests are conducted on the secondary batteries, and delivery is carried out after verification through a charge and discharge test to determine whether the specified performance and characteristics are met. However, with the increasing popularity of electric vehicles and the like, the capacity of secondary batteries is also increasing, and thus the energy consumption during charge and discharge testing is increasing.Furthermore, since many secondary batteries are used in electric vehicles and the like, a charge and discharge test device is required that can test a larger number of secondary batteries simultaneously and efficiently while saving energy. Therefore, Patent Document 1, for example, proposes a charge and discharge test system comprising: a bidirectional AC-DC converter with an AC side terminal connected to an AC power supply and a DC side terminal connected to a DC bus; a bidirectional DC-DC converter with one end connected to the DC bus and the other end connected to a sample (secondary battery); and a controller that controls the DC-DC converter so that the charge / discharge of the sample is controlled by the bidirectional DC-DC converter.The number of DC-DC converters connected to the DC bus is greater than the number of bidirectional AC-DC converters connected to the DC bus. The controller controls a plurality of bidirectional DC-DC converters according to the charging and discharging patterns of a plurality of probes each connected to the plurality of bidirectional DC-DC converters. The charging and discharging patterns of the plurality of probes are scheduled to minimize the regenerative energy supplied by the plurality of bidirectional DC-DC converters to the bidirectional AC-DC converters. Literature listPatent literature

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-154793 Summary of the inventionTechnical problem

[0004] According to Patent Document 1, by providing the DC bus for exchanging currents between the plurality of bidirectional DC-DC converters, the regenerative energy returned from the bidirectional AC-DC converter to the AC bus is reduced and the AC conversion loss in the bidirectional AC-DC converter is reduced, thereby improving the performance efficiency of the charging and discharging test system. However, each time new secondary batteries are to be tested, power must be supplied from the power grid (commercial AC power supply) and a plurality of secondary batteries to be tested must be charged, making it difficult to reduce energy consumption. Cost reduction is limited, and it may also be difficult to ensure energy supply.Furthermore, if a plurality of bidirectional DC / DC converters are controlled according to the charging and discharging patterns of the plurality of samples connected to the plurality of bidirectional DC / DC converters, the control device must be designed to minimize the regenerative energy supplied from the bidirectional DC / DC converters to the bidirectional AC / DC converter, which requires complicated control and may lead to increased costs. According to Patent Document 1, additionally connecting a storage battery to the DC bus reduces the power peaks of the regenerative AC power supply (bidirectional AC / DC converter) and contributes to reducing the size and cost of the regenerative AC power supply; however, it does not describe exactly how the storage battery is used, and its operation remains unclear.

[0005] The present invention was conceived in light of this circumstance. An object of the present invention is to provide a charge and discharge test apparatus that can perform cycle life evaluation at low cost without complicated control and significantly reduce power consumption by reusing energy supplied at an early stage multiple times and charging and discharging a plurality of secondary batteries. Task solution

[0006] A charging and discharging test apparatus according to the present invention that achieves this object is a charging and discharging test apparatus for simultaneously performing charging and discharging tests on a plurality of test objects, each of the test objects being a plurality of series-connected secondary batteries, the charging and discharging test apparatus comprising: an AC-DC converter having an AC-side (alternating current side) terminal connected to a commercial AC power supply and a DC-side (direct current side) terminal connected to a common DC bus; a plurality of bidirectional DC-DC converters, one end of which is connected to the common DC bus and the other end of which is connected to the test objects; a storage battery connected to the common DC bus; an auxiliary power generation device connected to the common DC bus;and a control device that controls each of the bidirectional DC-DC converters, wherein, during charging and discharging of each of the test objects, energy is transmitted and received between each of the test objects and the storage battery, and, when the storage battery is insufficient in energy, energy generated by the auxiliary power generation device is supplemented.;

[0007] In the charge and discharge test apparatus according to the invention, each of the test objects may be a battery module in which the plurality of secondary batteries may be connected in series and modularized, or a composite battery in which a plurality of battery modules identical to the battery module are connected in series.

[0008] In the charging and discharging testing device according to the invention, the AC converter is preferably a bidirectional AC converter.

[0009] In the charging and discharging test device according to the invention, the auxiliary energy generating device is preferably a solar panel.

[0010] The charging and discharging test apparatus according to the invention may comprise a voltage adjusting device connected to each of the test objects during the charging and discharging tests and controlled by the control device to make an adjustment such that a charging and discharging voltage of each of the secondary batteries is within a preset allowable deviation range. Advantageous effects of the invention

[0011] With the charging and discharging test device according to the invention, repeated charging and discharging processes can be performed between the test objects (a plurality of secondary batteries connected in series) and the storage battery. Since charging the storage battery at an early stage eliminates the need for power supply via the commercial AC power supply, energy consumption can be significantly reduced, and a large number of test objects (many secondary batteries) can be tested for their service life simultaneously with extremely low energy consumption. Instead of converting regenerative direct current (discharge energy) into regenerative alternating current when discharging the test object and then feeding it back into the commercial AC power supply, the regenerative direct current can be stored in the storage battery without conversion and reused when charging the test object.In this way, conversion losses of renewable energy can be avoided and renewable energy can be utilized highly efficiently. Since the discharge energy of the test object is stored in the storage battery and reused as charging energy, power peaks are reduced, and the power supply during the test operations can be stable and safe. Thus, energy can be supplied continuously and without interruption at a constant voltage from the storage battery, without readjustment in the event of a power outage, and the operating stability is excellent. Since energy generated by the auxiliary power generation device is supplemented when the storage battery is insufficient, the consumption and electricity bill of the commercial AC power supply can be reduced as much as possible, thus achieving cost reduction.

[0012] In the charge and discharge test device according to the invention, when the test object is a battery module in which a plurality of secondary batteries are connected in series and modularized, or an assembled battery in which a plurality of battery modules are connected in series, the charge and discharge tests of one or a plurality of the battery modules or the assembled batteries can also be performed as a charge and discharge test of each secondary battery. There is no need to separately perform the charge and discharge test of each secondary battery and the charge and discharge test of the battery modules or the assembled battery, thereby significantly reducing the burden and time-consuming nature of the charge and discharge tests compared to conventional tests.

[0013] In the charging and discharging test apparatus according to the invention, if the AC converter is a bidirectional AC converter, when the storage battery is in a fully charged state and the regenerative DC power (discharge energy) of the test object cannot be consumed as charging energy, excess regenerative DC power can be converted into regenerative AC power and fed back into the commercial AC power supply.

[0014] If the auxiliary power generation device in the charging and discharging testing device according to the invention is a solar panel, energy generated by solar energy can be supplemented in the event of an energy shortage and carbon dioxide emissions can be reduced.

[0015] If the charge and discharge test device according to the invention includes a voltage adjustment device connected to each of the test objects during the charge and discharge test operations and controlled by the controller to adjust the voltage so that the charge and discharge voltage of each of the secondary batteries falls within a preset fluctuation range, the influence of fluctuations in the performance values ​​(battery internal resistance values, etc.) of a plurality of series-connected secondary batteries can be reduced, and the charge and discharge test operations of all the secondary batteries can be completed simultaneously. Therefore, its efficiency is excellent, and overcharging, non-charging, non-discharging, and the like can be avoided, resulting in safe and accurate testing and highly reliable life testing. Short description of the drawing Fig. 1 is an explanatory diagram showing the structure of a charge and discharge inspection apparatus according to an embodiment of the present invention. Description of the embodiments

[0016] In the following, embodiments of the invention are described with reference to the accompanying drawings for a better understanding of the present invention.

[0017] A charging and discharging test device 10 according to a Fig. The embodiment of the invention shown in Figure 1 is used to simultaneously perform charge and discharge test operations on a plurality of test objects 11, each of the test objects 11 being a plurality of secondary batteries connected in series. This charge and discharge test device 10 is also used for activation and quality testing of produced secondary batteries (e.g., lithium-ion batteries), but particularly preferably for a service life test (prediction of battery service life).

[0018] The charging and discharging test device 10 is described in detail below.

[0019] As in Fig.As shown in FIG. 1, the charge and discharge test apparatus 10 includes a bidirectional AC-DC converter (an example of an AC-DC converter) 14 having an AC-side terminal connected to a commercial AC power supply 12 and a DC-side terminal connected to a common DC bus 13, and a plurality of bidirectional DC-DC converters 15, each of which has one end connected to the common DC bus 13 and the other end connected to the test object 11 in which a plurality of secondary batteries are connected in series. Furthermore, the charge and discharge test apparatus 10 includes a storage battery 16 connected to the common DC bus 13, an auxiliary power generation device 17 connected to the common DC bus 13, and a controller 18 that controls each of the bidirectional DC-DC converters 15.This charging and discharging test apparatus 10 controls the charging and discharging of each test object 11 (each secondary battery) by controlling each bidirectional DC-DC converter 15 with the controller 18. The charging and discharging of each test object 11 is performed by transmitting and receiving power between each test object 11 and the storage battery 16, but when the power in the storage battery 16 is insufficient, it is supplemented by power generated by the auxiliary power generation device 17.

[0020] The bidirectional AC converter 14, the bidirectional DC converters 15, the storage battery 16 and the auxiliary power generation device 17 form a power supply unit 20.

[0021] The above arrangement enables repeated charging and discharging tests while minimizing the power supply from the commercial AC power supply 12. Furthermore, the service life of a test object (a secondary battery) with a large capacity, which has been difficult to achieve until now, can be evaluated. Accordingly, by performing the charging and discharging test on a new secondary battery to be used for an electric vehicle or the like as a test object and storing the results (a charging curve and / or a discharging curve), the service life of a used secondary battery can be predicted by comparing it with the result of a charging and discharging test on a used secondary battery of the same type designated as the test object. Thus, it is possible to estimate whether to sell (use) the used secondary battery or dispose of it.an appropriate purchase or sales price can be established, and an expansion and optimization of the used market for secondary batteries (electric vehicles) can be promoted.

[0022] By switching from a conventional alternating current bus (AC bus) to a common DC bus 13, the charging and discharging test apparatus 10 eliminates the need to connect each bidirectional DC-DC converter 15 to a bidirectional AC-DC converter, simplifying the configuration. Note that, although at least one AC-DC converter is required to supply power from the commercial AC power supply 12 to the common DC bus 13, by using the bidirectional AC-DC converter 14, at a time when the storage battery 16 is fully charged and regenerative DC power (discharge energy) of the test object 11 (each secondary battery) cannot be used as charging energy, excess regenerative DC power can be converted into regenerative AC power and fed back to the commercial AC power supply 12.Furthermore, since the test object 11 and the storage battery 16 are each connected to the common DC bus 13, regenerative direct current (discharge energy) can be stored in the storage battery 16 when discharging the test object 11 and reused at the time the test object 11 is charged without conversion to regenerative alternating current. This avoids conversion loss of the regenerative energy and utilizes the regenerative energy highly efficiently, enabling the charging and discharging test of the test object 11 to be performed safely and continuously without being affected by power outages.

[0023] Furthermore, when there is a power shortage in the storage battery 16, the charge and discharge test 10 can reduce the usage or electricity bill of the commercial AC power supply 12, thus achieving cost reduction, since power generated by the auxiliary power generation device 17 can be supplemented. The auxiliary power generation device 17 can be of a single type, or a plurality of types can be used in combination. Note that, instead of the auxiliary power generation device 17, energy can be stored in the storage battery 16 using night-time power, or the auxiliary power generation device 17 and night-time power can be combined and used for various purposes depending on the weather and time. However, energy can also be stored in the storage battery 16 with the commercial AC power supply 12 when needed.

[0024] The auxiliary power generation device 17 is preferably a solar panel (solar power generation), but is not limited thereto, and may utilize renewable energy from wind power, etc.

[0025] The operation of the charging and discharging test device 10 is described below.

[0026] First, a plurality of secondary batteries are connected in series as the test object 11 to each bidirectional DC-DC converter 15. The test object 11 (each secondary battery) is initially in an uncharged state, and the storage battery 16 is previously charged via the commercial AC power supply 12 (or power generated by the auxiliary power generation device 17). When the control device 18 issues the charge command for each test object 11, the storage battery 16 supplies power to each test object, and each test object 11 (each secondary battery) is charged. After the charging process is completed, when the control device 18 issues the discharge command for each test object 11, each test object 11 supplies power to the storage battery 16, and each test object 11 (each secondary battery) is discharged.In this way, each device under test 11 is repeatedly charged and discharged by transmitting and receiving power between each device under test 11 and the storage battery 16. However, the charging and discharging times of each device under test 11 vary depending on characteristic differences (performance differences) (for example, different internal resistances, capacities, and the like). Accordingly, each device under test 11 is in an asynchronous state and repeatedly charges and discharges via the storage battery 16. The device under test 11 that has repeated charging and discharging a certain number of times and completed the charging and discharging test is advanced to the next step according to a command from the controller 18, and the test of the newly supplied device under test 11 is performed as needed.Since the energy generated by the auxiliary power generation device 17 supplements the energy in the event of a power shortage in the storage battery 16, the charge and discharge test can continue continuously. The storage battery 16 is preferably a lithium-ion battery, the capacity of which can be appropriately selected according to the total capacity of the test objects 11 being tested simultaneously. The number of test objects 11 and the number of secondary batteries comprising each test object 11 can thus be selected such that the total capacity of the test objects 11 being tested simultaneously falls within the capacity range of the storage battery 16, and secondary batteries of different capacities and types can also be tested simultaneously.

[0027] It is worth noting that any test object can be used as long as it is a test object in which a plurality of secondary batteries are connected in series, and also a battery module in which a plurality of secondary batteries are connected in series and modularized, or an assembled battery in which a plurality of battery modules are connected in series.

[0028] In this context, the charge and discharge test apparatus 10 may include a voltage adjusting device 21 connected to each test object 11 during the charge and discharge test operations and controlled by the control device 18 to adjust such that a charge and discharge voltage of each secondary battery constituting each test object 11 is within a preset allowable fluctuation range.

[0029] The voltage adjusting device 21 includes, for example, a device having a voltage measuring circuit that measures a charge and discharge voltage of each secondary battery with a voltage sensor connected in parallel to each secondary battery constituting each test object 11, and a bypass circuit having an on-off switch connected in parallel to each secondary battery.By controlling each voltage sensor and each bypass circuit (on-off switch) with the control unit 18 during the charge and discharge tests, a charge and discharge voltage of each secondary battery is measured at a preset measurement time interval. At this time, the bypass circuit connected in parallel to a secondary battery in which the measured charge and discharge voltage is higher than a reference voltage level is turned on for a specified period of time, so that a portion of the charge and discharge currents of the corresponding secondary battery are distributed to the bypass circuit. This reduces the charge and discharge currents flowing in the secondary battery with a charge and discharge voltage higher than the reference voltage level, and suppresses the charge and discharge, thereby reducing the overall variation in the charge and discharge voltage.The currents distributed to the bypass circuit are discharged via a resistor connected in series with the on / off switch and consumed as heat energy.

[0030] Despite the above description of the embodiments of the invention, the present invention is by no means limited to the arrangements described in the above embodiments and includes other embodiments and modifications that are conceivable within the scope of the facts described in the claims.

[0031] The secondary battery used as a test object includes, in addition to lithium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid storage batteries, and the like.

[0032] In the configurations described above, the bidirectional AC / DC converter is connected between the commercial AC power supply and the common DC bus; however, it does not always have to be a bidirectional AC / DC converter. Furthermore, the number of bidirectional DC / DC converters connected to the common DC bus is chosen appropriately. Industrial applicability

[0033] With the charging and discharging test device according to the invention, energy released at an early stage is repeatedly used to charge and discharge a large number of secondary batteries, and the service life can be evaluated cost-effectively without complicated control and with significantly reduced energy consumption. In particular, this can contribute to the expansion and optimization of the used market for electric vehicles (high-capacity secondary batteries). List of reference symbols

[0034] 10: Charging and discharging test device, 11: Test object, 12: Commercial AC power supply, 13: Common DC bus, 14: Bidirectional AC converter, 15: Bidirectional DC converter, 16: Storage battery, 17: Auxiliary power generation device, 18: Control device, 20: Power supply unit, 21: Voltage setting device QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] 2012-154793

[0003]

Claims

[1] A charging and discharging test device for simultaneously performing charging and discharging test operations on a plurality of test objects, each of which is a plurality of secondary batteries connected in series, the charging and discharging test device comprising: an AC converter having an AC side terminal connected to a commercial AC power supply and a DC side terminal connected to a common DC bus, a plurality of bidirectional DC-DC converters, one end of which is connected to the common DC bus and the other end of which is connected to each of the test objects, a storage battery connected to the common DC bus, an auxiliary power generation device connected to the common DC bus and a control unit that controls each of the bidirectional DC-DC converters, where at the time of charging and discharging of each of the test objects, energy is transmitted and received between each of the test objects and the storage battery, and in case of an energy shortage in the storage battery, energy is supplemented by energy generated by the auxiliary power generation device. [2] The charge and discharge test apparatus according to claim 1, wherein each of the test objects is a battery module in which the plurality of secondary batteries are connected in series and modularized, or a composite battery in which a plurality of battery modules identical to the battery module are connected in series. [3] A charging and discharging testing apparatus according to claim 1 or 2, wherein the AC converter is a bidirectional AC converter. [4] A charging and discharging testing apparatus according to any one of claims 1 to 3, wherein the auxiliary power generating means is a solar panel. [5] A charging and discharging test apparatus according to any one of claims 1 to 4, wherein the charging and discharging test apparatus comprises a voltage adjusting device connected to each of the test objects during the charging and discharging test operations and controlled by the controller to adjust such that a charging and discharging voltage of each of the secondary batteries is within a preset allowable deviation range.

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