Secondary battery inspection device

Abstract

To provide a secondary battery inspection device capable of suppressing power costs.SOLUTION: A secondary battery inspection device 1 has a voltage conversion unit 3, a plurality of secondary battery units 41, a link unit 5, and a storage battery 6. The voltage conversion unit 3 is connected to a system power supply 2 and converts voltage between the system voltage and a predetermined DC voltage. The secondary battery unit 41 can connect a plurality of secondary batteries in series. Each secondary battery unit 41 has a chopper circuit 411 capable of charging and discharging multiple secondary batteries 10. The link unit 5 connects each of the multiple secondary battery units 41 to the voltage conversion unit 3. The storage battery 6 is connected to the link unit 5 and performs charging and discharging for the multiple secondary battery units 41. The voltage conversion unit 3 detects the DC voltage (link voltage) generated in the link unit 5 and performs active power and regenerative power on the system power supply 2 to maintain the link voltage at the target voltage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a secondary battery inspection device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is known a secondary battery testing device that tests a plurality of secondary batteries simultaneously in parallel by charging and discharging the plurality of secondary batteries.

[0003] For example, Patent Document 1 discloses a secondary battery inspection device that includes a bidirectional AC / DC converter connected to a system power supply, an insulated bidirectional DC / DC converter connected to the bidirectional AC / DC converter, a group of chopper circuits connected to the bidirectional AC / DC converter, and a control unit that controls the chopper circuits. A plurality of secondary batteries to be inspected are connected to each chopper circuit, and the secondary batteries are charged and discharged by controlling the chopper circuits, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-54075 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, in the above-described conventional secondary battery testing devices, power from a power grid is charged to a secondary battery via a bidirectional AC / DC converter, an isolated bidirectional DC / DC converter, and a chopper circuit group, and power discharged from the secondary battery is regenerated to the power grid. However, because power loss occurs in the bidirectional AC / DC converter and the isolated bidirectional DC / DC converter, there is an increasing demand for further reduction in power costs.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a secondary battery inspection device that can reduce power costs. [Means for solving the problem]

[0007] The secondary battery inspection device of the present invention comprises: a voltage conversion unit connected to the system power supply, converting a voltage between the system voltage and a predetermined DC voltage, and outputting the converted voltage; a plurality of secondary battery units each including a chopper circuit capable of charging and discharging a plurality of secondary batteries; a link unit that connects each of the plurality of secondary battery units to the voltage conversion unit; a storage battery connected to the link unit and configured to charge and discharge the plurality of secondary battery units; a voltage control unit that controls the voltage conversion unit; and The voltage control unit detects the DC voltage generated in the link unit, and performs power running and regeneration on the system power supply so as to maintain the DC voltage at a target voltage. According to the above configuration, the discharged power from the multiple secondary batteries is charged to the storage battery, and the power from the storage battery is used to charge the multiple secondary batteries. The voltage control unit detects the DC voltage generated in the link unit and maintains the DC voltage at a target voltage to power the grid power supply and regenerate power. As a result, charging and discharging of the multiple secondary batteries is first performed on the storage battery connected to the link unit, making it possible to reduce the power received from the grid power supply.

[0008] Here, in the secondary battery inspection device of the present invention, the voltage conversion unit includes a bidirectional AC / DC conversion unit and a bidirectional DC / DC conversion unit, The voltage control unit may control the bidirectional DC / DC conversion unit based on the detected DC voltage.

[0009] In addition, in the secondary battery inspection device of the present invention, The target voltage may be set to a value that is higher than the total battery voltage of a plurality of secondary batteries connected in series and lower than the output voltage of the bidirectional AC / DC converter.

[0010] In addition, in the secondary battery inspection device of the present invention, a power supply control unit that instructs the chopper circuit to charge and discharge the plurality of secondary batteries connected thereto; The power supply control unit may control the chopper circuit so that a charging power value of a secondary battery unit that is being charged and a discharging power value of a secondary battery unit that is being discharged are equalized.

[0011] With this configuration, charging and discharging are performed evenly among the multiple secondary battery units, and power discharged from one secondary battery unit is efficiently used to charge another secondary battery unit, further reducing the amount of power received from the grid power supply. [Effects of the Invention]

[0012] According to the present invention, it is possible to reduce power costs. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram of a secondary battery inspection device 1 of the present embodiment. [Figure 2] FIG. 1 is a block diagram of a secondary battery inspection device 1A of a comparative example. [Figure 3] 10 is a diagram showing the state of input and output power to and from the power supply unit 4. FIG. [Figure 4] FIG. 4 is a diagram showing the state of power received from a power system 2 in a comparative example. [Figure 5] FIG. 4 is a diagram showing the state of power received from a power system 2 in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a secondary battery inspection device 1 according to the present invention will be described with reference to the accompanying drawings.

[0015] The secondary battery inspection device 1 is a device used for testing to confirm the performance of secondary batteries. For example, the secondary battery inspection device 1 is used to sequentially check the performance of manufactured secondary batteries. As shown in FIG. 1, the secondary battery inspection device 1 has a voltage conversion unit 3 connected to a system power supply 2, multiple power supply units 4, a link unit 5, a storage battery 6, and a power supply control unit 7.

[0016] The voltage conversion unit 3 is provided to maintain the voltage of the link unit 5 at a target voltage. The voltage conversion unit 3 is connected to a plurality of (e.g., eight) power supply units 4 via the link unit 5. In other words, the voltage conversion unit 3 and the plurality of power supply units 4 are connected by the link unit 5.

[0017] Specifically, the voltage conversion unit 3 includes an AC / DC conversion unit 31, a DC / DC conversion unit 32, and a voltage control unit 33. The AC / DC conversion unit 31 is connected between the system power supply 2 and the DC / DC conversion unit 32. The AC / DC conversion unit 31 controls the output voltage to the DC / DC conversion unit 32 to maintain an output target value (e.g., 400 V). Specifically, when the voltage on the DC / DC conversion unit 32 side becomes a value lower than the output target value (e.g., 399.99 V or lower), the AC / DC conversion unit 31 controls to transfer power from the system power supply 2 to the DC / DC conversion unit 32 (power running). When the voltage on the DC / DC conversion unit 32 side becomes a value higher than the output target value (e.g., 400.01 V or higher), the AC / DC conversion unit 31 controls to transfer power from the DC / DC conversion unit 32 side to the system power supply 2 (regeneration).

[0018] The DC / DC converter 32 transfers power from the AC / DC converter 31 side to the link unit 5 (described later) side, or from the link unit 5 side to the AC / DC converter 31 side, in response to a command from the voltage control unit 33. The DC / DC converter 32 may be, for example, a chopper circuit (a non-insulated bidirectional DC / DC converter) or an insulated bidirectional DC / DC converter. The DC / DC converter 32 may be a step-down type, a step-up type, or a step-up / step-down type, depending on the target voltage value of the direct current voltage generated in the link unit 5 (hereinafter referred to as the "link voltage").

[0019] The voltage control unit 33 inputs, outputs, and processes signals. The voltage control unit 33 may be an MCU (Micro Controller Unit) or the like built into the voltage conversion unit 3, or may be a general-purpose computer that externally controls the voltage conversion unit 3. The voltage control unit 33 executes various functions. It monitors the link voltage and transmits a command value to the DC / DC conversion unit 32 so as to maintain the link voltage at a target voltage value (e.g., 360 V). Specifically, when the link voltage is lower than the target voltage value (e.g., 358 V or lower), the voltage control unit 33 controls the DC / DC conversion unit 32 so as to transfer power from the AC / DC conversion unit 31 side to the link unit 5 side. Furthermore, when the link voltage is higher than the target voltage value (e.g., 362 V or higher), the voltage control unit 33 controls the DC / DC conversion unit 32 so as to transfer power from the link unit 5 (described later) side to the AC / DC conversion unit 31 side. The link voltage may be monitored, for example, once per second.

[0020] In this way, the voltage conversion unit 3 detects the link voltage and performs power running and regeneration for the system power source 2 by converting the voltage between the system voltage and the link voltage (predetermined DC voltage) using the AC / DC conversion unit 31 and the DC / DC conversion unit 32 so as to maintain the link voltage at the target voltage.

[0021] Each power supply section 4 has a plurality of (for example, four) secondary battery units 41. Each power supply section 4 is used to charge and discharge the secondary batteries 10 in order to test each of the plurality of secondary batteries 10. Each power supply section 4 is connected to a power supply control section 7, which will be described later. In this embodiment, the secondary battery testing device 1 is configured to have a plurality of (for example, 1,000) power supply sections 4, but is not limited to this. The number of power supply sections 4 may be one or more.

[0022] The secondary battery unit 41 allows a plurality of (e.g., 64) secondary batteries 10 to be connected in series. For example, the secondary battery unit 41 has a tray (not shown) that stores the plurality of secondary batteries 10 connected in series. The secondary battery unit 41 has a chopper circuit 411 and a battery management unit 412 (the battery management unit is indicated as "BMU" in FIG. 1).

[0023] The chopper circuit 411 is configured to be able to charge and discharge the multiple secondary batteries 10 housed in the secondary battery unit 41. For example, the chopper circuit 411 is configured to be able to perform CCCV control on the multiple secondary batteries 10. For example, the chopper circuit 411 may be a step-down type, a step-up type, or a step-up / step-down type.

[0024] Specifically, the chopper circuit 411 performs charging as follows using CCCV control. That is, the chopper circuit 411 charges the multiple secondary batteries 10 with a constant current (CC, Constant Current) (CC charging) until the voltage reaches a target voltage (e.g., 4.2 V). Then, when the voltage of the secondary batteries 10 reaches the target voltage, the chopper circuit 411 charges the multiple secondary batteries 10 while maintaining the constant voltage (CV, Constant Voltage) until they are fully charged (CV charging).

[0025] The battery management unit 412 is a device that monitors a plurality of secondary batteries 10. The battery management unit 412 monitors, for example, the charge state of each secondary battery 10. One battery management unit 412 monitors a predetermined number of secondary batteries 10 stored in the secondary battery unit 41. The secondary battery unit 41 is provided with a number of battery management units 412 sufficient to monitor all of the secondary batteries 10 in the secondary battery unit 41. Each chopper circuit 411 and each battery management unit 412 is connected to the power supply control unit 7, which will be described later.

[0026] The storage battery 6 is connected to a link unit 5 that connects the voltage conversion unit 3 and multiple secondary battery units 41. The storage battery 6 charges and discharges the multiple secondary battery units 41. That is, the storage battery 6 stores the power discharged from the multiple power supply units 4 connected to the same link unit 5. The storage battery 6 also supplies power to charge the multiple power supply units 4 connected to the same link unit 5. When the voltage of the storage battery 6 drops and the link voltage also drops, the voltage conversion unit 3 supplies power from the system power supply 2.

[0027] The power supply control unit 7 acquires information from the battery management unit 412 of each secondary battery unit 41. The power supply control unit 7 also controls the chopper circuit 411 of each secondary battery unit 41. The power supply control unit 7 receives a signal indicating the charge state of each secondary battery 10 from the battery management unit 412. The power supply control unit 7 transmits a control signal to the chopper circuit 411 to cause it to charge or discharge the secondary battery 10. The power supply control unit 7 controls charging and discharging by the chopper circuit 411 in each power supply unit 41 based on a predetermined algorithm and the charge state of each secondary battery 10 acquired from the battery management unit 412.

[0028] As described above, the secondary battery inspection device 1 has a voltage conversion unit 3, a plurality of secondary battery units 41, a link unit 5, and a storage battery 6. The voltage conversion unit 3 is connected to the system power supply 2. The secondary battery unit 41 can connect a plurality of secondary batteries 10 in series. Each secondary battery unit 41 has a chopper circuit 411 that can charge and discharge the plurality of secondary batteries 10. The link unit 5 connects each of the plurality of secondary battery units 41 to the voltage conversion unit 3. The storage battery 6 is connected to the link unit 5 and charges and discharges the plurality of secondary battery units 41. The voltage conversion unit 3 detects a link voltage and performs power running and regeneration on the system power supply 2 so as to maintain the link voltage at a target voltage.

[0029] According to the above configuration, the discharged power from the plurality of secondary batteries 10 is charged to the storage battery 6, and the power from the storage battery 6 is used to charge the plurality of secondary batteries 10. The power shortage or surplus is detected by the voltage conversion unit 3, and power running and regeneration are performed for the system power supply 2. As a result, charging and discharging of the plurality of secondary batteries 10 is first performed on the storage battery 6 connected to the link unit 5, making it possible to suppress the power received from the system power supply 2.

[0030] The secondary battery inspection device 1 further includes a power supply control unit 7 that instructs the chopper circuit 411 to charge and discharge the multiple secondary batteries 10 connected thereto. The power supply control unit 7 controls the chopper circuit 411 so that the charging power value of the secondary battery unit 41 that is being charged and the discharging power value of the secondary battery unit 41 that is being discharged are equalized.

[0031] According to the above configuration, the multiple secondary battery units 41 are evenly charged and discharged. Therefore, the power discharged from the secondary battery units 41 is efficiently used to charge other secondary battery units 41, which makes it possible to further reduce the power received from the system power supply 2.

[0032] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design modifications are possible within the scope of the claims.

[0033] (Example) The secondary battery inspection device 1 shown in FIG. 1 was used as an example. The secondary battery inspection device 1A shown in FIG. 2 was used as a comparative example. As shown in FIG. 2, a power supply section 4A of the comparative example is configured to include a voltage conversion section 3A and a plurality of secondary battery units 41, unlike the power supply section 4 of the example. Furthermore, the voltage conversion section 3A of the comparative example is configured to not include a voltage control section 33, unlike the voltage conversion section 3 of the example. The plurality of power supply sections 4A are configured to be connected to a system power supply 2 (three-phase three-wire 200V). The number of power supply sections 4 of the example was eight. The number of power supply sections 4A of the comparative example was eight.

[0034] The characteristics of each configuration used in the simulations of the example and comparative example are described below. A total of 256 secondary batteries 10 were connected to one power supply unit 4. Four secondary battery units 41 were installed to one power supply unit 4, with 64 secondary batteries 10 (battery voltage 4.2 V, current 5 A or 6 A) connected in series to each secondary battery unit 41. As a result, the total voltage of one set of secondary batteries 10 was 270 V max. If a step-down chopper with a capacity of 2 kW and a current of 5 A is used for the chopper circuit 411, the output (battery side voltage) of the chopper circuit 411 is 270 V, and therefore the input (grid power supply side) must have a voltage 10% or higher than the battery side voltage (i.e., a voltage of 300 V or higher). Furthermore, to pass a commanded current from the grid power supply 2 to the storage battery 6, a chopper circuit with a capacity of 10 kW and a current of 30 A is required as the DC / DC converter 32. Specifically, taking into account voltage drops along the way, the battery voltage was calculated to be 4.5V, the current was 6A, and there were a total of 256 batteries. The power required for the test was calculated to be approximately 7kW, with a capacity of 10kW to allow for some margin. If a step-down chopper is used in the DC / DC converter 32, the input voltage must be at least 15V higher than the link voltage (battery-side voltage). Taking these factors into consideration, a commonly used 360V, 40A general-purpose battery was used for the storage battery 6. Because the storage battery 6 is directly connected to the link unit 5, the target voltage for the link voltage was the storage battery voltage of 360V, and the input voltage for the DC / DC converter 32 (the output voltage of the AC / DC converter 31) was set to 400V.

[0035] In one test cycle, the chopper circuit 411 in each secondary battery unit 41 controls the 64 secondary batteries 10 as follows: The chopper circuit 411 performs CC charging up to 4.2 V, CV charging until the batteries are fully charged, and then discharges the batteries until the voltage reaches a specified level.

[0036] The charging and discharging algorithm of the chopper circuits 411 in the power supply units 4 and 4A, which is executed by the power supply control unit 7, will now be described. As shown in Fig. 3, eight power supply units 4 (shown as power supplies 1 to 8 in Fig. 3) (eight power supply units 4A in the comparative example) were controlled to have an operating rate of 90%. As shown in Fig. 3, each of the eight power supply units 4 (eight power supply units 4A in the comparative example) was controlled so that the operating timing was shifted sequentially and uniformly.

[0037] As shown in Fig. 4, it can be seen that the power received rises to 15.0 kW. On the other hand, as shown in Fig. 5, it can be seen that the power received in the example is always 0.7 kW.

[0038] As shown in Table 1, the simulation results showed that the amount of power consumed by the comparative example was 2.74 kWh. On the other hand, the simulation results showed that the amount of power consumed by the example was 0.72 kWh. As such, it was found that the example was able to reduce power costs compared to the comparative example.

[0039] [Table 1] [Explanation of symbols]

[0040] 1 Secondary battery inspection equipment 2 power supplies 3 Voltage conversion section 4 Power supply section 5 Link section 6. Storage battery 7 Power supply control unit 10 Secondary battery 31 AC / DC conversion section 32 DC / DC conversion section 33 Voltage control section 41 Secondary battery unit 411 Chopper Circuit 412 Battery Management Unit

Claims

1. a voltage conversion unit connected to the system power supply and converting a voltage between the system voltage and a predetermined DC voltage; a plurality of secondary battery units each including a chopper circuit capable of charging and discharging a plurality of secondary batteries; a link unit that connects each of the plurality of secondary battery units to the voltage conversion unit; a storage battery connected to the link unit and configured to charge and discharge the plurality of secondary battery units; a voltage control unit that controls the voltage conversion unit; and The voltage control unit detects the DC voltage generated in the link unit, and performs power generation and regeneration on the system power supply so as to maintain the DC voltage at a target voltage.

2. The secondary battery inspection device according to claim 1, the voltage conversion unit includes a bidirectional AC / DC conversion unit and a bidirectional DC / DC conversion unit, The secondary battery testing device is characterized in that the voltage control unit controls the bidirectional DC / DC conversion unit based on the detected DC voltage.

3. 3. The secondary battery inspection device according to claim 2, A secondary battery inspection device characterized in that the target voltage is set to a value higher than the total battery voltage of multiple secondary batteries connected in series and lower than the output voltage of the bidirectional AC / DC conversion unit.

4. 4. The secondary battery inspection device according to claim 1, a power supply control unit that instructs the chopper circuit to charge and discharge the plurality of secondary batteries connected thereto; The secondary battery inspection device is characterized in that the power supply control unit controls the chopper circuit so that the charging power value of the secondary battery unit being charged and the discharging power value of the secondary battery unit being discharged are equal.

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