JP7351053B1 - Secondary battery testing device and secondary battery testing system equipped with the same - Google Patents

Abstract

[Problem] A secondary battery testing device capable of suppressing overcharging and/or overdischarging of a secondary battery even when a malfunction occurs in measuring the voltage of the secondary battery, and a secondary battery tester equipped with the same. Provides battery testing systems. [Solution] A secondary battery testing device that tests a plurality of secondary batteries connected in series, the device is connected in series with each secondary battery, and a preset voltage value is set for the secondary battery. a protection means that generates a voltage according to a set voltage value, and a control section that controls the connection between the protection means and the secondary battery, and the control section controls when the voltage of the secondary battery reaches the set voltage value. Connect the secondary battery and the protection means so that current flows through the protection means when the [Selection diagram] Figure 3

Description

The present invention relates to a secondary battery testing device for testing the charging and/or discharging of secondary batteries such as lithium ion batteries, and a secondary battery testing system equipped with the same, and particularly relates to a secondary battery testing system including a plurality of secondary batteries connected in series. The present invention relates to a secondary battery testing device and a secondary battery testing system including the same.

Conventionally, rechargeable secondary batteries have been widely used as power sources for IT devices such as smartphones and tablet terminals. In recent years, the shift to electric vehicles has been accelerating at a global level with the aim of realizing a decarbonized society, and the importance of secondary batteries as a power source for electric vehicles is increasing. Lithium ion batteries are generally used as secondary batteries for electric vehicles. Lithium-ion batteries have high volumetric and gravimetric energy densities, allowing for rapid charging and discharging, and there is no memory effect that shortens the usable time due to repeated charging without using up the charged power. Due to its advantages, it is used in various devices and equipment, including electric cars.

At the final stage of the manufacturing process, secondary batteries undergo a charge/discharge test to confirm that they meet predetermined performance and characteristics in terms of quality and safety before being shipped. In addition, since the characteristics of a secondary battery vary greatly depending on the internal resistance value of the secondary battery, the internal resistance value is calculated by ACIR (Alternating Current Internal Resistance) test, DCIR (Direct Current Internal Resistance) test, etc. Secondary batteries are sometimes ranked based on internal resistance values. ACIR testing is a test method that applies a minute alternating current signal to the secondary battery to separate and measure the resistance and reactance components of the battery, while DCIR testing involves discharging the secondary battery with a constant current. However, this is an inspection method that calculates the internal resistance value from the discharge current value and the voltage drop at a specific timing.

In charging and discharging tests of secondary batteries, charging and discharging of the secondary batteries are controlled and tests are conducted to confirm the performance and characteristics of the secondary batteries. As a control method for charging and discharging this secondary battery, especially in charge/discharge tests of lithium ion batteries, control using a constant current/constant voltage charging method and a constant current/constant voltage discharging method (hereinafter referred to as "CCCV control") is used. ) is commonly practiced. In CCCV control, first, the voltage of the secondary battery is increased (or decreased) by charging (or discharging) with a constant current (constant current) (hereinafter, this control is referred to as "CC control"), and the voltage When reaches a predetermined voltage, the charging (or discharging) current is finely adjusted to maintain this predetermined voltage (Constant Voltage) (hereinafter, this control is referred to as "CV control"), and the predetermined voltage is When the conditions (for example, a predetermined elapsed time, a predetermined end current value, etc.) are met, charging (or discharging) is ended. By switching from CC control to CV control, overcharging and overdischarging of the secondary battery is prevented. Prevention of overcharging and overdischarging of secondary batteries is an important issue. Particularly in the case of lithium-ion batteries, when overcharged, needle-shaped metallic lithium (dendrites) are deposited on the surface of the negative electrode inside the battery, and this breaks through the separator separating the negative and positive electrodes, causing an internal short circuit. However, there is a risk that the battery may explode or catch fire. In addition, if a lithium-ion battery is over-discharged for a long time, the copper foil used for the battery's negative electrode may melt and deteriorate, eventually making it impossible to charge. There is a possibility that a large amount of gas will be generated due to the progress of the reductive decomposition reaction of the electrolytic solution in parallel with the elution. Even in secondary batteries other than lithium ion batteries, overcharging and overdischarging can cause battery damage, performance deterioration, and the like. Therefore, in a charge/discharge test of a secondary battery, it is necessary to prevent the secondary battery from being overcharged or overdischarged.

In the charge/discharge test of secondary batteries at the final stage of the manufacturing process, basically all batteries are tested, so in order to perform the test efficiently, multiple secondary batteries are tested at the same time. For example, by connecting multiple secondary batteries in series (hereinafter referred to as "series connection method") or in parallel (hereinafter referred to as "parallel connection method"), all connected secondary batteries Charging or discharging batteries simultaneously. Conventional charge/discharge tests for secondary batteries, especially lithium ion batteries, employ a parallel connection method. A charge/discharge test using a parallel connection method measures the voltage of each secondary battery individually, so it is suitable for charge/discharge tests of lithium-ion batteries, which require strict voltage measurement from a safety standpoint. However, in order to perform charge/discharge tests using a parallel connection method, a high-performance, expensive, and large-sized charge/discharge power supply that can output and control high current is required. This may lead to higher costs, etc. Furthermore, when a charging/discharging power source is used for each secondary battery, a cable connecting the positive and negative electrodes of the secondary battery is also required for each secondary battery, which can also be a factor in increasing costs. The use of high-output charging/discharging power supplies and the increase in the number of cables lead to an increase in heat emitted from the entire test equipment, including the secondary battery, and there is a risk that the test will be conducted in a high-temperature environment.

In the case of a charge/discharge test using a series connection method, it is possible to alleviate the problems of the above-mentioned charge/discharge test using a parallel connection method. However, in charge/discharge tests using series connection methods, the overall voltage of secondary batteries connected in series is often measured, and in this case, it is difficult to determine the exact voltage of each individual secondary battery. This point can be particularly problematic when testing lithium ion batteries. Furthermore, since the secondary batteries are connected in series, control for preventing overcharging and overdischarging tends to be more complicated than in the case of parallel connection.

Therefore, devices and systems have been proposed that take advantage of the advantages of the series connection method and attempt to solve the above problems.

For example, in Japanese Unexamined Patent Application Publication No. 2013-29485 (Patent Document 1), a plurality of units each including a secondary battery to be subjected to a charge/discharge test, four switches as switching means, and a switching control section are connected in series. A charging/discharging test device has been proposed that performs various charging/discharging tests and prevents overcharging and overdischarging by configuring a circuit that charges, discharges, and bypasses a secondary battery by a combination of on/off switches. The unit is also equipped with an ammeter that measures the current flowing through the secondary battery and a voltmeter that measures the voltage of the secondary battery. The switching control section controls charging and discharging by CCCV control or the like based on information about the current from the ammeter and the voltage from the voltmeter.

Japanese Patent Laid-Open No. 2019-102267 (Patent Document 2) discloses a switching element (first switching element) for separating the secondary batteries from the series connection state when a plurality of series-connected secondary batteries are subjected to constant current discharge. A charge/discharge test system has been proposed that uses a series control circuit with a diode and a parallel control circuit with a switching element (second switching element) to suppress fluctuations in discharge current and accurately measure discharge capacity. ing. The charging/discharging test system has individual control means for controlling charging and discharging for each secondary battery, and the individual control means includes a comparator that measures the voltage of the secondary battery during discharge and compares it with a specified voltage. , has a driver that switches the first and second switching elements on and off according to the measured voltage of the secondary battery.

JP2013-29485A JP2019-102267A

As in the charge/discharge test device of Patent Document 1 and the charge/discharge test system of Patent Document 2, overcharging and/or overdischarging of secondary batteries connected in series is prevented by turning on/off a switch (switching element). For example, in a device that uses switching, a bypass circuit that disconnects the secondary battery from the series connection and a circuit that allows current to flow through the secondary battery are configured, a switch is provided to switch between the two circuits, and when the switch is on, the bypass circuit is enabled. This is intended to prevent overcharging and/or overdischarging. In charging and discharging tests of secondary batteries using such means, CV control to maintain a predetermined voltage usually monitors the voltage of the secondary battery and turns on the switch when the voltage reaches a predetermined voltage. It repeatedly performs an operation to prevent current from flowing to the secondary battery, and an operation to turn off the switch and allow current to flow to the secondary battery when the voltage deviates from a predetermined voltage.

However, if a problem occurs in measuring the voltage of the secondary battery while CV control is being performed, for example if the voltmeter fails or the voltage value transmission path is disconnected, accurate voltage values cannot be obtained. When the voltage reaches the specified voltage, the switch should be turned on to prevent current from flowing to the secondary battery, but a situation arises where the switch remains off and current continues to flow to the secondary battery. obtain. In this case, overcharging and/or overdischarging cannot be prevented.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to prevent overcharging and/or overdischarging of the secondary battery even if a problem occurs in measuring the voltage of the secondary battery. An object of the present invention is to provide a secondary battery testing device and a secondary battery testing system equipped with the same that can suppress the situation where the above occurs.

The present invention relates to a secondary battery testing device that tests a plurality of secondary batteries connected in series, and the above-mentioned object of the present invention is to test a plurality of secondary batteries connected in series. a protection unit that generates a voltage according to a set voltage value that is a preset voltage value; and a control unit that controls connection between the protection unit and the secondary battery, and the control unit This is achieved by connecting the secondary battery and the protection means so that when the voltage of the secondary battery reaches the set voltage value, a current flows through the protection means.

The above-mentioned object of the present invention is such that the control unit includes a voltage measuring means for measuring the voltage of each of the secondary batteries, and determines whether the voltage measured by the voltage measuring means has reached the set voltage value. and a switching means that switches the connection state of the secondary battery and the protection means based on the result of determination by the switching control unit, or the set voltage value is It is a charging set voltage value used when charging the secondary battery, and the protection means is provided with a protection circuit that generates a voltage according to the charging set voltage value, or the secondary battery is set. By further comprising a time measuring unit that measures the time from when charging of the secondary battery starts until the voltage of the secondary battery reaches the charging set voltage value, or the set voltage value is set to the charging set voltage value. It is a set voltage value for discharging used when discharging a secondary battery, and the protection means is provided with a protection circuit that generates a voltage according to the set voltage value for discharging, or the secondary battery is By further comprising a time measuring unit that measures the time from the start of discharging the battery until the voltage of the secondary battery reaches the set voltage value for discharging, or the protection circuit includes a Zener diode and a By being composed of a resistor, or the set voltage value is a set voltage value for charging used when charging the secondary battery and a set voltage for discharging used when discharging the secondary battery. and the protection means includes a charging protection circuit that generates a voltage according to the charging setting voltage value, and a discharging protection circuit that generates a voltage according to the discharging setting voltage value. Alternatively, the time from the start of charging of the secondary battery until the voltage of the secondary battery reaches the set charging voltage value and the time from the start of discharging of the secondary battery until the voltage of the secondary battery reaches the set voltage value for charging By further comprising a time measuring section that measures at least one of the times until the voltage of the battery reaches the set voltage value for discharging, or the charging protection circuit and the discharging protection circuit each have a Zener The charging protection circuit may be configured with a diode and a resistor, or the protection circuit may further include a current adjustment circuit that adjusts the current flowing through the protection circuit, or the charging protection circuit may further comprising a charging current adjustment circuit that adjusts the current flowing through the discharge protection circuit, and the discharge protection circuit further comprising a discharge current adjustment circuit that adjusts the current flowing through the discharge protection circuit. achieved.

Further, the present invention relates to a secondary battery testing system including the above secondary battery testing device, and the above object of the present invention is achieved by further comprising a management device that manages the operation of the secondary battery testing device. .

According to the secondary battery testing device and the secondary battery testing system of the present invention, when the voltage of the secondary battery reaches the set voltage value, the battery is connected in series to the secondary battery and the voltage is adjusted according to the set voltage value. Since current flows through the protective means that generates the voltage, even if a problem occurs in measuring the voltage of the secondary battery during CV control, the protective means will function and prevent the secondary battery from being overcharged and/or Overdischarge can be suppressed.

1 is a diagram showing a configuration example (first embodiment) of a secondary battery testing system including a secondary battery testing device according to the present invention. It is a schematic diagram which shows the example of the time change of the electric current and voltage of a lithium ion battery in the charge/discharge test by CCCV control. It is a figure showing the example of composition (1st embodiment) of a control board and a series cell part. It is a figure showing the example of composition (1st embodiment) of a protection means. It is a flowchart which shows the operation example (1st Embodiment) of a control board and a series cell part. It is a figure which shows the example of a structure when a switching means is arrange|positioned in the latter stage of a protection means. It is a figure which shows the example of a structure when switching means are integrated. It is a figure which shows the example of a structure (2nd Embodiment, 3rd Embodiment) of a switching means, a protection means, and a lithium ion battery in the secondary battery test apparatus based on this invention. It is a figure showing the example of composition (4th embodiment) of a secondary battery testing system provided with the secondary battery testing device concerning the present invention. It is a flowchart which shows the example of operation of a time measurement part.

The secondary battery testing device according to the present invention performs a charge/discharge test using a series connection method. In other words, charging, discharging, or discharging multiple secondary batteries such as lithium ion batteries connected in series, and checking whether each secondary battery has performance and characteristics that meet predetermined requirements. Conduct the test. Since the test is conducted using a series connection method, it is possible to conduct the test without using a high-output, large-sized charging/discharging power supply, and it is possible to suppress the number of cables connected to the positive and negative electrodes of the secondary battery. Heat emitted from the entire device can be suppressed.

In order to prevent overcharging and/or overdischarging of a secondary battery in a charge/discharge test using a series connection method, the secondary battery testing device according to the present invention installs protective measures for each secondary battery to be tested. It is equipped with The protection means is connected in series with each secondary battery, and when charging and discharging the secondary battery under CCCV control, for example, when switching from CC control to CV control, in other words, the voltage of the secondary battery is When a predetermined voltage (set voltage value) is reached, the connection state between the secondary battery and the protection means is switched so that current flows through the protection means. The protection means is configured to generate a voltage according to the set voltage value, and when current flows through the protection means, the voltage of the secondary battery is reset to the set voltage value. As a result, overcharging can be prevented by preventing the voltage of the secondary battery from becoming an overvoltage during charging, and overdischarging can be prevented by preventing the voltage of the secondary battery from dropping during discharging. In this way, overcharging and overdischarging of the secondary battery is prevented, so problems with voltage measurement during CV control can be avoided, such as when switching with a bypass circuit to prevent overcharging and overdischarging of the secondary battery. It is possible to avoid a situation where the secondary battery is overcharged or overdischarged due to the above.

In addition, in the secondary battery testing device according to the present invention, the time (hereinafter referred to as , "charging time"), and/or the time from the start of discharging the secondary battery until the voltage of the secondary battery reaches the set voltage value for discharging (set voltage value for discharging) (hereinafter referred to as "charging time") , "discharge time"). This information can be used to eliminate cell balance collapse, etc. Cell balancing is a function that equalizes the voltage of each secondary battery (cell) connected in series. This is a collapse of cell balance. Since electric vehicles and the like use battery packs (batteries) in which secondary batteries are connected in series, it is necessary to eliminate cell imbalance in order to use the battery packs efficiently. Ranking each secondary battery based on the charging time and/or discharging time measured by the secondary battery testing device according to the present invention, and determining secondary batteries to be combined in series connection based on the rank. This makes it possible to minimize disruption of cell balance and improve efficient use of the battery pack.

Note that the present invention can be realized as a secondary battery testing device that performs a charging-only test, a discharging-only test, or a both charging and discharging test of a secondary battery. Further, the present invention may be realized as the above-mentioned secondary battery testing device, or may be realized as a secondary battery testing system that includes a management device that manages the operation of the secondary battery testing device in addition to the secondary battery testing device. You may do so.

Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same components are given the same reference numerals, and their explanations may be omitted. Furthermore, the configurations and the like in the following description are merely examples, and the present invention is not limited thereto. Furthermore, the following description focuses on the main configurations and operations for implementing the present invention, and descriptions of general-purpose configurations, operations, etc. necessary for implementing the present invention will be simplified or omitted. are doing.

FIG. 1 shows a configuration example (first embodiment) of a secondary battery testing system including a secondary battery testing device according to the present invention.
The secondary battery testing system 1 of this embodiment performs a charge/discharge test using CCCV control using a lithium ion battery as a test subject. CCCV control is a control method commonly used in charge/discharge tests of lithium ion batteries. FIG. 2 is a schematic diagram showing an example of the time change in current and voltage of a lithium ion battery in a charge/discharge test using CCCV control. FIG. 2(A) shows the time change during charging, and FIG. 2(B) This is the time change during discharge.

In a charge/discharge test using CCCV control, control is performed to shift from CC control to CV control both during charging and discharging. That is, at the time of charging, as shown in FIG. 2(A), the lithium ion battery is first charged with a constant current Ib having a current value I1 as CC control to increase the voltage Vb of the lithium ion battery, and the voltage Vb When reaches a preset voltage value V1 (set voltage value, set voltage value for charging) (for example, 4.25 V), shift to CV control and change current Ib so that voltage Vb maintains voltage value V1. The lithium ion battery is charged by gradually decreasing the current value from I1, and when a preset time t1 (for example, 3 hours) has elapsed, charging is terminated. When the current Ib becomes zero at the end of charging, the voltage Vb slowly decreases. At the time of discharging, as shown in FIG. 2(B), the lithium ion battery is first discharged with a constant current Ib of current value I3 as CC control to lower the voltage Vb of the lithium ion battery, and the voltage Vb is set in advance. When the set voltage value V2 (set voltage value, set voltage value for discharging) (for example, 1V) is reached, shift to CV control and change the current Ib from the current value I3 so that the voltage Vb maintains the voltage value V2. The lithium ion battery is gradually lowered to discharge the lithium ion battery, and when a preset time t2 (for example, 1 hour) has elapsed, the discharge is ended. Note that the charging and/or discharging may be terminated when the current Ib reaches a preset current value (sometimes referred to as "end current value") instead of depending on the elapsed time. For example, during charging, when the current Ib reaches the end current value (current value I2), as shown in FIG. 2(A), charging ends, and during discharging, as shown in FIG. 2(B), Then, when the current Ib reaches the end current value (current value I4), the discharge is ended. In FIG. 2A, the current Ib reaches the end current value at time t1, but the current value at time t1 does not have to be the end current value. Similarly, in FIG. 2B, the current Ib reaches the end current value at time t2, but the current value at time t2 does not have to be the end current value.

The secondary battery testing system 1 prevents overcharging and overdischarging of the lithium ion battery in charge/discharge tests by shifting from CC control to CV control in CCCV control. In particular, in the case of a lithium ion battery, even if the voltage Vb slightly exceeds (for example, 0.1 V) overcharging, there is a risk of explosion or fire, so strict monitoring of the voltage Vb is required in CV control.

Note that the secondary battery test system 1 may perform a charge/discharge test of a lithium ion battery using a control method other than CCCV control, such as constant power constant voltage control (CPCV control). Further, the secondary battery testing system 1 may test secondary batteries other than lithium ion batteries, such as nickel-cadmium batteries, nickel-metal hydride batteries, lead-acid batteries, and the like.

As shown in FIG. 1, the secondary battery testing system 1 includes a secondary battery testing device 10 that performs charge/discharge tests on a plurality of lithium ion batteries, and a management device 20 that manages the operation of the secondary battery testing device 10. . The secondary battery testing device 10 and the management device 20 are connected via a wired LAN (local area network) that conforms to communication standards such as Ethernet. Note that the secondary battery testing device 10 and the management device 20 may be connected by a cable of another standard, or may be connected by a wireless LAN or the like instead of a wired connection.

The management device 20 determines the type of charge/discharge test performed by the secondary battery testing device 10, that is, whether it is a test during charging (hereinafter referred to as "charging test") or a test during discharging (hereinafter referred to as "discharge test"). Mode information Mi indicating this is transmitted to the secondary battery testing apparatus 10. A value indicating a "charging test" (for example, 0) and a value indicating a "discharging test" (for example, 1) are determined in advance, and the corresponding values are set in the mode information Mi in accordance with the form of the charging and discharging test.

The management device 20 also transmits information (hereinafter referred to as "test setting information") Ti necessary for the secondary battery testing device 10 to perform a charge/discharge test using CCCV control to the secondary battery testing device 10. . Specifically, in a charging test where the mode information Mi is "charging test", the management device 20 sets the current value I1, which is the set value in CC control during charging, and the voltage value V1, which is the set value in CV control. , and time t2, which is the set time, are transmitted as the test setting information Ti, and in a discharge test where the mode information Mi is "discharge test", the current value I3, which is the set value in CC control during discharge, and the current value I3, which is the set value in CV control, are transmitted as the test setting information Ti. The voltage value V2, which is the set value, and the time t4, which is the set time, are transmitted as test setting information Ti. In addition, at the start of a charge/discharge test, the setting values for both charging and discharging are sent to the secondary battery testing apparatus 10 as test setting information Ti, and mode information Mi is sent to the secondary battery testing apparatus 10 at the start of a charge test and a discharge test. It may also be transmitted to the battery testing device 10.

A general-purpose information device such as a personal computer may be used as the management device 20, and the processing in the management device 20 may be performed by a dedicated application (application program) or a combination of a dedicated application and a general-purpose application. , a dedicated device may be used as the management device 20. Note that the secondary battery testing apparatus 10 may hold part or all of the test setting information Ti in advance. The secondary battery testing device 10 may be provided with means for directly receiving the mode information Mi and the like. When the secondary battery testing device 10 holds all the test setting information Ti and is provided with means for receiving the mode information Mi, the management device 20 may not be provided.

The secondary battery testing device 10 includes a power supply controller 110, a charge/discharge power supply 120, a control board 130, a series cell section 140, and a voltage monitor controller 150, and includes a plurality of lithium ions mounted in the series cell section 140 and connected in series. The battery is subjected to a charge/discharge test using CCCV control.

The power supply controller 110 controls the current from the charge/discharge power supply 120 based on the mode information Mi and test setting information Ti transmitted from the management device 20 and the voltage Vb of each lithium ion battery mounted in the series cell section 140. Control Ia. The value of the voltage Vb of each lithium ion battery is measured by the control board 130, and the measured voltage value is input to the power supply controller 110 via the voltage monitor controller 150 and the management device 20. In order to perform a charge/discharge test using CCCV control, the power supply controller 110 determines the mode of the charge/discharge test based on the mode information Mi, and in the charge test, performs each of the CC control and CV control during charging included in the test setting information Ti. In the discharge test, the current Ia is controlled by setting each set value of CC control and CV control during discharge included in the test setting information Ti as targets.

The charging/discharging power supply 120 causes a current Ia to flow through the lithium ion battery mounted in the series cell section 140 under the control of the power supply controller 110. As the charge/discharge power supply 120, a stabilized DC power supply that produces stable DC current is used. DC stabilized power supplies include linear power supplies (series power supplies, dropper power supplies) and switching power supplies, and as the charge/discharge power supply 120, a switching power supply that is widely used in charging and discharging tests of secondary batteries is used. Linear power supplies use an AC transformer to reduce the voltage of input alternating current, then rectify it using a rectifier circuit using diodes, and stabilize the voltage using a smoothing circuit using a capacitor. A switching power supply first performs rectification, and then converts the rectified current into a pulse wave using a switching element, treating the rectified current as a pseudo alternating current due to the pulse wave. Adjust voltage. Due to these differences in system, there are differences in noise and size between linear power supplies and switching power supplies.Linear power supplies have less noise but have a larger housing size, while switching power supplies have more noise but have a larger case size. , the housing size becomes smaller. Since a switching power supply is used as the charge/discharge power supply 120, noise countermeasures are taken as necessary.

The control board 130 is equipped with protection means for preventing overcharging and overdischarge of the lithium ion battery mounted in the series cell section 140, and a switching means for switching to the protection means. The protection means and switching means mounted on the control board 130 are provided for each lithium ion battery mounted on the series cell section 140, and the protection means and switching means and the lithium ion batteries are connected in series. With this connection state, a charge/discharge test using a series connection method is performed. The control board 130 is also equipped with voltage measuring means for measuring the voltage Vb of each lithium ion battery mounted in the series cell section 140. Details of the control board 130 and the series cell section 140 will be described later.

The voltage monitor controller 150 aggregates the values of the voltages Vb of each lithium ion battery measured by voltage measuring means mounted on the control board 130. The voltage values aggregated by the voltage monitor controller 150 are immediately transmitted to the management device 20, transmitted to the power supply controller 110 via the management device 20, and used for control processing and the like in the power supply controller 110. It is also possible to provide a means for displaying the aggregated voltage values in the voltage monitor controller 150 and display the voltage value of each lithium ion battery as appropriate, thereby making it possible to monitor the voltage value during the charge/discharge test. . Note that the management device 20 may be provided with means for displaying the voltage value.

In devices that perform charging/discharging tests using a conventional parallel connection method, a power supply controller 110 also functions as a voltage monitor controller 150, and the voltage value of a lithium ion battery is transmitted to the power supply controller via a charging/discharging power supply. There is something. In this case, noise from the switching power supply, which is a charging/discharging power supply, may affect the transmitted voltage value. On the other hand, in the secondary battery testing device 10 , the voltage value of the lithium ion battery is collected in the voltage monitor controller 150 and input to the power supply controller 110 via the management device 20 . In this way, the power supply controller 110 and the voltage monitor controller 150 are not directly connected but are separated, and the voltage value of the lithium ion battery does not go through the charge/discharge power supply 120, so the influence of noise from the switching power supply can be suppressed and Accurate voltage values can be transmitted. Note that in cases where there is little influence of noise between the power supply controller 110 and the voltage monitor controller 150 or noise countermeasures have been taken, the voltage value of the lithium ion battery may be transmitted directly from the voltage monitor controller 150 to the power supply controller 110. You can also do it. Even in this case, since the voltage value of the lithium ion battery does not pass through the charging/discharging power supply 120, the influence of noise from the switching power supply can be suppressed.

Details of the control board 130 and the series cell section 140 will be explained.
FIG. 3 shows a configuration example of the control board 130 and the series cell section 140.
A plurality of lithium ion batteries are mounted in the series cell section 140, and in this embodiment, twelve lithium ion batteries 141a to 141l are mounted. The series cell section 140 may have a configuration in which lithium ion batteries 141a to 141l are individually mounted, or a lithium ion battery as an assembled battery is mounted in the series cell section 140, and the lithium ion batteries 141a to 141l are lithium ion batteries. It may also be configured as a battery cell. Note that the number of lithium ion batteries mounted in the series cell section 140 can be set arbitrarily.

The control board 130 includes 12 switching means 131a to 131l, 12 protection means 132a to 132l, 12 voltage measurement means 133a to 133l, and a switching control unit 134 corresponding to the lithium ion batteries 141a to 141l. is installed. The switching means 131a, the protection means 132a, the voltage measurement means 133a and the lithium ion battery 141a form one set, and similarly the switching means 131b, the protection means 132b, the voltage measurement means 133b and the lithium ion battery 141b form one set. Twelve such sets are configured, each set is connected in series, and a charging/discharging power supply 120 is further incorporated in the connection to form a circuit. The switching control section 134 is connected to the switching means 131a to 131l, the protection means 132a to 132l, and the voltage measuring means 133a to 133l, and is also connected to the voltage monitor controller 150. Note that the switching means 131a to 131l, the voltage measuring means 133a to 133l, and the switching control section 134 constitute a control section. In addition, in the following, when there is no need to distinguish between the switching means 131a to 131l, the protection means 132a to 132l, the voltage measuring means 133a to 133l, and the lithium ion batteries 141a to 141l, representatively, excluding a to l, The switching means 131, the protection means 132, the voltage measuring means 133, and the lithium ion battery 141 may be included. Furthermore, for other constituent elements, the symbols excluding a to l may typically represent the constituent elements.

The switching means 131 is a single pole double throw type (single pole double throw type) switch having three contacts 131-1, 131-2 and 131-3, and the contacts 131-1 and 131-2 are connected. However, contacts 131-1 and 131-3 are connected. The contact 131-2 is connected to the positive electrode of the lithium ion battery 141 of the series cell section 140, and the contact 131-3 is connected to the protection means 132. Regarding the contacts 131-1, the contacts 131a-1 of the switching means 131a are connected to the charging/discharging power supply 120, and the contacts 131b-1 to 131l-1 of the switching means 131b to 131l are connected to the negative electrodes of the lithium ion batteries 141a to 141k, respectively. is connected to. The switch used as the switching means 131 may be mechanical or electronic as long as it can switch the connection between the contact 131-1 and the contacts 131-2 and 131-3.

The switching means 131 performs switching when transitioning from CC control to CV control in a charge/discharge test using CCCV control. That is, in CC control, contact 131-1 and contact 131-2 are connected, and in CV control, contact 131-1 and contact 131-3 are connected. The timing of transition from CC control to CV control is detected by inputting a control switching signal Sc output from the switching control section 134. That is, when the switching means 131 receives the control switching signal Sc, it switches the connection destination of the contact 131-1 from the contact 131-2 to the contact 131-3. By this switching, the charging/discharging power supply 120 and the lithium ion batteries 141a to 141l are directly connected in series in CC control, and are connected in series via protection means 132a to 132l, respectively, in CV control.

The protection means 132 generates a voltage according to a set voltage value in CV control in order to prevent overcharging and overdischarging of the lithium ion battery 141. That is, the protection means 132 generates a voltage according to the voltage value V1 in the CV control in the charging test, and generates a voltage in accordance with the voltage value V2 in the CV control in the discharging test.

An example of the configuration of the protection means 132 is shown in FIG.
The protection means 132 includes a charging protection circuit 132-1, a discharging protection circuit 132-2, and a switching means 132-3. The charging protection circuit 132-1 and the discharging protection circuit 132-2 have the same configuration, and in CV control, the charging protection circuit 132-1 is set at the set voltage value during the charging test (charging set voltage value). A voltage corresponding to a certain voltage value V1 is generated, and the discharge protection circuit 132-2 generates a voltage corresponding to a voltage value V2 which is a set voltage value (discharge set voltage value) at the time of a discharge test. The switching means 132-3 switches between the charging protection circuit 132-1 and the discharging protection circuit 132-2 according to the type of charging/discharging test (charging test, discharging test).

The switching means 132-3, like the switching means 131, is a single pole double throw type (single pole double throw type) switch having three contacts 132-31, 132-32 and 133-33. 132-31 and 132-32 are connected, and contacts 132-31 and 133-33 are connected. The contact 132-31 is connected to the contact 131-3 of the switching means 131, the contact 132-32 is connected to the charging protection circuit 132-1, and the contact 132-33 is connected to the discharging protection circuit 132-2. . Similar to the switching means 131, the switch used as the switching means 132-3 may be mechanical or electronic as long as it can switch the connection between the contact 132-31 and the contacts 132-32 and 132-33.

In a charge/discharge test using CCCV control, the switching means 132-3 connects the contacts 132-31 and 132-32 when performing a charging test, and connects the contacts 132-31 and 132-32 when performing a discharge test. Connect 33. The mode of the charge/discharge test is determined based on the mode switching signal Sm output from the switching control section 134. That is, when the mode switching signal Sm has a value indicating "charging test" (for example, 0), the switching means 132-3 connects the contacts 132-31 and 132-32, and the mode switching signal Sm indicates "discharging test". In the case of a value indicating (for example, 1), contacts 132-31 and 132-33 are connected. Note that, instead of the value of the mode switching signal Sm, the switching control unit 134 outputs the mode switching signal Sm when changing the mode of the charge/discharge test, and the switching means 132-3 outputs the contact when the mode switching signal Sm is input. The connection destination of 132-31 may be switched.

The charging protection circuit 132-1 is composed of a resistor 132-11, a Zener diode 132-12, a transistor 132-13, and a diode 132-14. The transistor 132-13 and the diode 132-14 form a circuit (current adjustment circuit, charging current adjustment circuit) that generates a corresponding voltage and adjusts the current flowing to the charging protection circuit 132-1.

The Zener diode 132-12 has a characteristic that its insulation is broken when a constant reverse voltage is applied, and current flows while keeping the voltage constant. Therefore, in a charging test in which the contacts 132-31 and 132-32 of the switching means 132-3 are connected, the lithium ion battery 141 reaches the voltage value V1, the CC control is shifted to the CV control, and the switching means When contacts 131-1 and 131-3 of 131 are connected, a reverse voltage is applied to the Zener diode 132-12, and a constant voltage in the opposite direction to that of the lithium ion battery 141 is generated in the charging protection circuit 132-1. By adjusting the constant voltage with the resistor 132-11 so that the magnitude of this constant voltage is equal to the voltage value V1, the voltage of the lithium ion battery 141 is reset to the set voltage value, and the overvoltage for the lithium ion battery 141 is can be prevented.

The transistors 132-13 are NPN type transistors and function as an amplifier. The base of transistor 132-13 is connected to resistor 132-11 and Zener diode 132-12. With this configuration, even if the current flowing into the charging protection circuit 132-1 becomes large, fluctuations in the current flowing through the resistor 132-11 and the Zener diode 132-12 are suppressed, and the voltage generated by the charging protection circuit 132-1 is suppressed. can be kept constant. In charge/discharge tests for lithium ion batteries, the magnitude of the current flowing through the lithium ion battery may be changed, such as during rapid charging, to change the charging or discharging time, but even in such cases, the charging protection circuit 132- 1 can absorb changes in the magnitude of the current by adjusting the transistors 132-13. The diode 132-14 functions as a freewheeling diode (freewheeling diode). Note that when a MOSFET (metal oxide semiconductor field effect transistor) is used as the transistor 132-13 and a body diode (parasitic diode) formed within the MOSFET can be used instead of a freewheeling diode, the diode 132-14 is unnecessary. Further, if there is no need to adjust the current flowing through the charging protection circuit 132-1, or if the current is adjusted by another means, the transistor 132-13 and the diode 132-14 are unnecessary.

Similar to the charging protection circuit 132-1, the discharging protection circuit 132-2 includes a resistor 132-21, a Zener diode 132-22, a transistor 132-23, and a diode 132-24. A circuit (current adjustment circuit, discharge current control circuit).

The function and operation of the discharge protection circuit 132-2 are similar to those of the charge protection circuit 132-1.

Note that the charging protection circuit 132-1 and the discharging protection circuit 132-2 do not need to have the configuration shown in FIG. 4 as long as they can generate a voltage according to the set voltage value in CV control. The charging protection circuit 132-1 and the discharging protection circuit 132-2 do not have to have the same configuration.

Voltage measuring means 133 measures voltage Vb of lithium ion battery 141. The voltage measuring means 133 is connected in parallel with the lithium ion battery 141 and measures the voltage Vb of the lithium ion battery 141 at predetermined time intervals. The measured voltage value is output to the switching control section 134.

The switching control unit 134 determines whether the voltage Vb of each lithium ion battery 141 has reached the set voltage value.

The switching control unit 134 selects the mode information Mi and voltage value V1 (in the case of a charging test) or voltage value V2 (discharge test) from among the mode information Mi and test setting information Ti transmitted from the management device 20 to the secondary battery testing device 10. (for exams). Further, the switching control unit 134 sequentially inputs voltage values Vbv_a to Vbv_l of the lithium ion batteries 141a to 141l measured at predetermined time intervals by the voltage measuring means 133a to 133l. Note that in the following, when there is no need to distinguish between the voltage values Vbv_a to Vbv_l, the voltage value Vbv may be used as a representative, except for a to l.

The switching control unit 134 determines the type of charge/discharge test based on the mode information Mi. When the mode information Mi is "charging test", the switching control unit 134 uses the voltage value V1 as the set voltage value and determines whether the voltage Vb of each lithium ion battery 141 has reached the voltage value V1. If there is a lithium ion battery 141 whose voltage value Vbv is equal to or higher than the voltage value V1, a control switching signal Sc is output to the switching means 131 corresponding to the lithium ion battery 141. When the mode information Mi is "discharge test", the switching control unit 134 uses the voltage value V2 as the set voltage value and determines whether the voltage Vb of each lithium ion battery 141 has reached the voltage value V2. If there is a lithium ion battery 141 whose voltage value Vbv is equal to or lower than the voltage value V2, a control switching signal Sc is output to the switching means 131 corresponding to the lithium ion battery 141.

Furthermore, the switching control section 134 outputs a mode switching signal Sm to the switching means 132-3 in the protection means 132 based on the mode information Mi. When the mode information Mi is "charging test", the mode switching signal Sm is set to "charging test", and when the mode information Mi is "discharging test", the mode switching signal Sm is set to "discharging test", and switching is performed. The control unit 134 outputs a mode switching signal Sm. Note that the mode information Mi may be output as is as the mode switching signal Sm.

The switching control unit 134 outputs the input voltage values Vbv_a to Vbv_l to the voltage monitor controller 150.

Note that the switching control unit 134 may be implemented as a program running on the CPU by mounting a general-purpose CPU, memory, etc. on the control board 130, or may be implemented as hardware.

An example of the operation of the configuration of the control board 130 and the series cell section 140 will be described with reference to the flowchart of FIG. 5. Note that a description of general-purpose operations such as operations when an error occurs will be omitted. Further, at the start of operation, it is assumed that in the switching means 131, the contacts 131-1 and 131-2 are connected.

The switching control unit 134 inputs the voltage value V1 or voltage value V2 in the mode information Mi and test setting information Ti output from the management device 20 (step S10).

The switching control unit 134 sets the mode switching signal Sm to "charging test" when the mode information Mi is "charging test", and sets the mode switching signal Sm to "discharging test" when the mode information Mi is "discharging test". , and outputs the mode switching signal Sm to the switching means 132-3 in the protection means 132 (step S20).

The switching means 132-3 connects the contact 132-31 and the contact 132-32 when the mode switching signal Sm is "charging test", and connects the contact 132-31 and the contact when the mode switching signal Sm is "discharging test". Connect 132-33. (Step S30).

The voltage measuring means 133 measures the voltage Vb of the lithium ion battery 141 and outputs the measured voltage value Vbv to the switching control section 134 (step S40).

When the mode information Mi is "charging test" (step S50), the switching control unit 134 compares the voltage value Vbv and the voltage value V1, and when the voltage value Vbv becomes equal to or higher than the voltage value V1 (step S60), the switching control unit 134 changes the voltage A control switching signal Sc is output to the switching means 131 corresponding to the lithium ion battery 141 having the value Vbv (step S70). When the switching means 131 receives the control switching signal Sc, it switches the connection destination of the contact 131-1 from the contact 131-2 to the contact 131-3 (step S80).

When the mode information Mi is "discharge test" (step S50), the switching control unit 134 compares the voltage value Vbv and the voltage value V2, and when the voltage value Vbv becomes equal to or less than the voltage value V2 (step S90), the switching control unit 134 changes the voltage A control switching signal Sc is output to the switching means 131 corresponding to the lithium ion battery 141 having the value Vbv (step S100). When the switching means 131 receives the control switching signal Sc, it switches the connection destination of the contact 131-1 from the contact 131-2 to the contact 131-3 (step S110).

The operations of steps S40 to S110 are repeatedly performed at the timing when the voltage Vb is measured until the test (charging test, discharging test) is completed (step S120).

Although the secondary battery testing device 10 includes one control board 130 and one series cell unit 140, it may also include multiple control boards and/or multiple series cell units, and the number of control boards and series cells may vary. The number of parts does not have to be the same. Accordingly, a plurality of voltage monitor controllers 150 may be provided, or only one voltage monitor controller 150 may be provided.

For example, the following modifications can be made to this embodiment.

In the secondary battery testing apparatus 10, the switching means 131 is arranged before the protection means 132, but it may be arranged after the protection means 132. FIG. 6 shows a part of a configuration example in which the switching means 131 is arranged in this manner. As shown in FIG. 6, the switching means 131 is arranged after the protection means 132, and the contact 131-3 of the switching means 131 is connected to the protection means 132, and the contact 131-1 is connected to the positive electrode of the lithium ion battery 141. are doing. Similarly, the switching means 132-3 of the protection means 132 may also be arranged after the charging protection circuit 132-1 and the discharging protection circuit 132-2, instead of before them.

Alternatively, the switching means 131 and the switching means 132-3 of the protection means 132 may be integrated to use one single-pole three-throw switch. FIG. 7 shows a part of a configuration example in which a switching means 135, which is a single-pole three-throw switch, is used instead of the switching means 131 and the switching means 132-3. The switching means 135 has four contacts 135-1, 135-2, 135-3 and 135-4, and the contact 135-1 is connected to the contacts 135-2, 135-3 and 135-4, respectively. ing. The contact 135-2 is connected to the positive electrode of the lithium ion battery 141, the contact 135-3 is connected to the charging protection circuit 132-1 in the protection means 136, and the contact 135-4 is connected to the discharge protection circuit in the protection means 136. Connected to 132-2. The switching means 135 connects contacts 135-1 and 135-2 in CC control, connects contacts 135-1 and 135-3 in CV control in a charging test, and connects contacts 135-1 and 135-3 in CV control in a charging test. In the CV control, contacts 135-1 and 135-4 are connected.

In the secondary battery testing device 10, the protective means 132 is designed to function in both the charging test and the discharging test in the charging/discharging test, but the protective means 132 is designed to function only during one of the tests. It's okay. In CV control in a test in which the protection means does not function, for example, a bypass circuit is provided to prevent current from flowing to the lithium ion battery 141.

FIG. 8 shows a part of a configuration example of a secondary battery testing device in such a case. FIG. 8 shows an example of the configuration of the switching means, protection means, and lithium ion battery in the secondary battery testing device, and FIG. FIG. 8B shows a configuration example (third embodiment) in which the protection means functions only in the discharge test.

In the second embodiment, the switching means 131 and the lithium ion battery 141 are the same as in the first embodiment, and the charging protection circuit 132-1 in the protection means 137 is also the same as in the first embodiment; The switching means 137-3 in this embodiment is different from that in the first embodiment. That is, among the three contacts 137-31, 137-32, and 137-33 of the switching means 137-3, the contacts 137-31 and 137-32 are similar to the switching means 132-3 in the first embodiment. They are connected to the contact 131-3 of the switching means 131 and the charging protection circuit 132-1, respectively, and the contact 137-33 is connected to the negative electrode side of the lithium ion battery 141. Therefore, in a charge/discharge test using CCCV control, when performing a discharge test, contacts 137-31 and 137-33 are connected, so contacts 131-1 and 131-3 of switching means 131 are connected under CV control. Then, current no longer flows to the lithium ion battery 141. This prevents overcharging of the lithium ion battery 141.

In the third embodiment, the switching means 131 and the lithium ion battery 141 are the same as in the first embodiment, and the discharge protection circuit 132-2 in the protection means 138 is also the same as in the first embodiment. The switching means 138-3 in this embodiment is different from that in the first embodiment. That is, among the three contacts 138-31, 138-32, and 138-33 of the switching means 138-3, the contacts 138-31 and 138-33 are similar to the switching means 132-3 in the first embodiment. They are connected to the contact 131-3 and the discharge protection circuit 132-2 of the switching means 131, respectively, and the contact 138-32 is connected to the negative electrode side of the lithium ion battery 141. Therefore, in a charging/discharging test using CCCV control, when performing a charging test, contacts 138-31 and 138-32 are connected, so contacts 131-1 and 131-3 of switching means 131 are connected under CV control. Then, current no longer flows to the lithium ion battery 141. This prevents over-discharging of the lithium ion battery 141.

Other embodiments of the present invention will be described.
Cell balance is an important function in a battery pack (battery) in which a plurality of secondary batteries (cells) are connected in series, which are used in electric vehicles and the like. In such a battery pack, voltage imbalance (cell imbalance) may occur between the secondary batteries connected in series due to variations in characteristics of the individual secondary batteries. When charging a battery pack with such an imbalance, the secondary battery with the higher voltage will reach the charging upper limit voltage (the upper limit voltage for safe charging) first, and the voltage will reach the charging upper limit voltage first. Charging stops even though there are secondary batteries that are not loaded. On the other hand, when discharging an unbalanced battery pack, the secondary batteries with lower voltage reach the discharge end voltage (the lowest voltage for discharging within a safe range) first, and the secondary batteries can still be used. Even if it exists, it will become unusable as a battery pack unless it is recharged. If there is a voltage imbalance between the secondary batteries in this way, the performance of the battery pack cannot be fully utilized, and there is also a risk of overcharging or overdischarging.

There are active and passive methods for cell balancing to reduce the voltage imbalance between secondary batteries in a battery pack, but the active method has issues such as increased cost, while the passive method has problems with energy efficiency. There are issues such as a decline in Instead of such secondary processing, if secondary batteries that make up a battery pack are combined with secondary batteries with less variation in characteristics, the voltage imbalance between secondary batteries can be reduced. I can do it.

In order to combine secondary batteries with less variation in characteristics, each secondary battery is ranked based on the characteristics of the secondary batteries related to cell balance, and the secondary batteries to be combined are determined based on that rank. . It is possible to use the internal resistance value of a secondary battery determined by ACIR test or DCIR test as the characteristic that is the basis for ranking, but it is not a direct characteristic such as internal resistance, but a direct Secondary characteristics derived from the characteristics, such as charging time, which is the time from the start of charging until reaching the set voltage value for charging, and discharging time, which is the time from the start of discharging until reaching the set voltage value for discharging. It is also possible to use

Configuration example of a secondary battery testing system that measures charging time and discharging time used for ranking secondary batteries to eliminate such voltage imbalance between secondary batteries (fourth embodiment) is shown in Figure 9. In the secondary battery testing system 2 according to the fourth embodiment, compared to the secondary battery testing system 1 according to the first embodiment shown in FIG. Regarding this, the secondary battery testing device 30 includes a time measuring section 160, the control board 130 is replaced by a control board 230, and the switching control section 134 is replaced by a switching control section 234 in the control board 230. Other components are the same as in the first embodiment. The time measuring section 160 is connected to the control board 230.

In addition to mode information Mi and test setting information Ti, the management device 40 generates a signal Scs indicating the start of a charging test (hereinafter referred to as a "charging test start signal") and a signal indicating the start of a discharging test (hereinafter referred to as a "charging test start signal") in a charge/discharge test. , Sds (referred to as a “discharge test start signal”) to the secondary battery testing device 30. The secondary battery testing device 30 that has received the charge test start signal Scs and the discharge test start signal Sds inputs these to the time measurement section 160. Regarding the charging test start signal Scs and the discharge test start signal Sds, the charging test and the discharging test may be started when the secondary battery testing device 30 receives them, or the secondary battery testing device 30 may start the charging test and the discharging test when the secondary battery testing device 30 receives them. Even if the management device 40 detects the start of the test and discharge test (for example, by transmitting a start signal from the secondary battery testing device 30 to the management device 40), and sends the signal after detection. good. In the latter case, the charging test start signal Scs and the discharge test start signal Sds may be input and output within the secondary battery testing device 30 without going through the management device 40. Furthermore, when the secondary battery testing device 30 receives the mode information Mi, the charging test and the discharging test may be started, and the mode information Mi may be used as the charging test start signal Scs and the discharge test start signal Sds.

Similar to the switching control unit 134, the switching control unit 234 of the control board 230 determines whether the voltage Vb of each lithium ion battery 141 has reached the set voltage value. An identifier is assigned in advance to each lithium ion battery 141 mounted in the series cell section 140 that is the target of the charge/discharge test, and when the switching control section 234 determines that the voltage Vb has reached the set voltage value, the switching control section 234 Information (hereinafter referred to as “arrived battery information”) Ab in which an identifier corresponding to the lithium ion battery 141 determined to be set is set is output to the time measurement unit 160.

The time measuring unit 160 measures the charging time and discharging time for each lithium ion battery 141.

When the time measurement unit 160 receives the charging test start signal Scs transmitted from the management device 40, it starts measuring the charging time. Then, when the reached battery information Ab from the switching control unit 234 is input, it is assumed that the voltage Vb of the lithium ion battery 141 corresponding to the identifier set in the reached battery information Ab has reached the set voltage value (set voltage value for charging). , the elapsed time from the measurement start point to that point is calculated as the charging time for the lithium ion battery 141. The calculated charging time is output as the charging time Tc together with the reached battery information Ab.

Similarly, upon receiving the discharge test start signal Sds transmitted from the management device 40, the time measurement unit 160 starts measuring the discharge time. Then, when the reached battery information Ab from the switching control unit 234 is input, it is assumed that the voltage Vb of the lithium ion battery 141 corresponding to the identifier set in the reached battery information Ab has reached the set voltage value (set voltage value for discharging). , the elapsed time from the measurement start point to that point is calculated as the discharge time for the lithium ion battery 141. The calculated discharge time is output as the discharge time Td together with the reached battery information Ab.

In order to aggregate the measured charging time and discharging time, the secondary battery testing device 30 transmits, for example, the reached battery information Ab, the charging time Tc, and the discharging time Td output from the time measurement unit 160 to the management device 40. do.

Note that the time measuring unit 160 distinguishes between a charging test and a discharging test based on the difference between the charging test start signal Scs and the discharging test start signal Sds, and measures the charging time and the discharging time. The time measuring unit 160 also inputs the information to the measuring unit 160, so that the time measuring unit 160 determines whether it is a charging test or a discharging test based on the mode information Mi, and uses the same signal as the signal indicating the start of the charging test and the signal indicating the start of the discharging test. You can also do it.

The time measurement unit 160 may be implemented as a program running on the CPU by mounting a general-purpose CPU, memory, etc. on the secondary battery testing device 30, or may be implemented as hardware.

In the configuration of the secondary battery testing system 2, an example of the operation of the time measuring section 160 will be described with reference to the flowchart of FIG. 10. FIG. 10(A) is a flowchart showing an operational example of charging time measurement, and FIG. 10(B) is a flowchart showing an operational example of discharging time measurement. Note that, similar to the flowchart shown in FIG. 5, description of general-purpose operations such as operations when an error occurs will be omitted.

When the time measurement unit 160 receives the charging test start signal Scs from the management device 40 (step S210), it starts measuring the charging time (step S220).

When the time measurement unit 160 receives the reached battery information Ab from the switching control unit 234 (step S230), it calculates the charging time (step S240), and outputs it as the charging time Tc together with the reached battery information Ab (step S250). .

When the time measuring unit 160 finishes calculating the charging time of all the lithium ion batteries 141 (step S260), it finishes measuring the charging time. If calculation of all charging times has not been completed (step S260), the process returns to step S230.

Furthermore, upon receiving the discharge test start signal Sds from the management device 40 (step S270), the time measurement unit 160 starts measuring the discharge time (step S280).

When the time measurement unit 160 receives the reached battery information Ab from the switching control unit 234 (step S290), it calculates the discharge time (step S300), and outputs it as the discharge time Td together with the reached battery information Ab (step S310). .

When the time measurement unit 160 finishes calculating the discharge times of all the lithium ion batteries 141 (step S320), it ends the measurement of the discharge times. If calculation of all discharge times has not been completed (step S320), the process returns to step S290.

Note that in this embodiment, the secondary battery testing device 30 includes the time measurement section 160, but other components may include the time measurement section 160. For example, the management device 40 may include the time measurement section 160, or the switching control section 234 of the control board 230 may also function as the time measurement section 160. Further, although the time measuring section 160 measures the charging time and the discharging time, it may be configured to measure only one of them. If the secondary battery testing device 30 is a device that performs only either a charging test or a discharging test, the time measuring unit 160 will measure only the corresponding time.

An example of a method for ranking lithium ion batteries 141 using measured charging and discharging times will be described.

As a simple ranking method, there is a method in which only charging time or discharging time is used, and classification is performed at fixed or variable time intervals to classify ranks. Although this is a simple method, since lithium ion batteries with similar charging or discharging times will belong to the same rank, it can be expected to suppress cell imbalance.

As a ranking method using both charging time and discharging time, the ranking is done in two stages: first, ranking is done by charging time or discharging time, and then for each rank, ranking is done by the other time that is not being used. There are ways to separate them. Ranking at each stage is performed by the above-mentioned method of dividing at constant or variable time intervals. By dividing the ranks into two stages, more accurate ranking can be expected than by ranking in one stage.

As a method of dividing ranks into two stages, there is a method that applies the concept of Coulomb efficiency (charging and discharging efficiency). Coulombic efficiency is the ratio of the discharge capacity during discharging to the amount of electricity charged during charging, expressed as a percentage, and lithium-ion batteries with the same Coulombic efficiency are considered to have the same performance. be able to. In the charging and discharging tests, assuming that charging and discharging are performed at the same rate (current), the ratio of discharging time to charging time (hereinafter referred to as "charging and discharging time efficiency") is This value is approximately the same as Coulomb efficiency. Therefore, first, ranks are performed based on charging time or discharging time, and in each rank, ranking is performed based on charging/discharging time efficiency. For example, the discharging time is divided into ranks at fixed or variable time intervals, and in each rank, the charging/discharging time efficiency is divided into ranks at fixed or variable intervals. By performing such a ranking, it is expected that the ranking will be more closely matched to the performance of the lithium ion battery.

Note that the method for ranking the lithium ion batteries 141 is not limited to the above method as long as charging time and/or discharging time is used.

Ranking of the lithium ion batteries 141 using the above-mentioned charging time and discharging time can be performed by the secondary battery testing device 30 or the management device 40, or by another device.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention. Further, matters not explicitly disclosed in the above form do not deviate from the scope of what a person skilled in the art would normally do, and values that can be easily assumed by a person skilled in the art should be adopted. I can do it.

Furthermore, the present invention is also applicable to devices and systems that charge and discharge secondary batteries. For example, the present invention can be applied to a power storage system used as a power source at a charging station (charging stand, charging spot), etc., which is a facility for charging electric vehicles. Such power storage systems store electricity in advance through charging and supply the stored electricity to electric vehicles, etc. Therefore, by applying the present invention during charging and discharging, overcharging and/or overcharging of secondary batteries can be prevented. Discharge can be suppressed.

1, 2 Secondary battery testing system 10, 30 Secondary battery testing device 20, 40 Management device 110 Power supply controller 120 Charging/discharging power supply 130, 230 Control board 131, 132-3, 135, 137-3, 138-3 Switching means 132, 136, 137, 138 Protection means 132-1 Charge protection circuit 132-2 Discharge protection circuit 133 Voltage measurement means 134, 234 Switching control section 140 Series cell section 141 Lithium ion battery 150 Voltage monitor controller 160 Time measurement section

Claims (13)

A secondary battery testing device that tests multiple secondary batteries connected in series,
a protection means connected in series with each of the secondary batteries to generate a voltage according to a set voltage value that is a preset voltage value for the secondary battery;
A control unit that controls connection between the protection means and the secondary battery,
The secondary battery is characterized in that the control unit connects the secondary battery and the protection means so that when the voltage of the secondary battery reaches the set voltage value, a current flows through the protection means. Next battery testing equipment. The control section,
Voltage measuring means for measuring the voltage of each of the secondary batteries;
a switching control unit that determines whether the voltage measured by the voltage measuring means has reached the set voltage value;
The secondary battery testing device according to claim 1, further comprising a switching unit that switches the connection state of the secondary battery and the protection unit based on the result of the determination by the switching control unit. The set voltage value is a charging set voltage value used when charging the secondary battery,
The secondary battery testing device according to claim 1, wherein the protection means includes a protection circuit that generates a voltage according to the set charging voltage value. The secondary battery test according to claim 3, further comprising a time measuring unit that measures the time from when charging of the secondary battery is started until the voltage of the secondary battery reaches the set voltage value for charging. Device. The set voltage value is a discharge set voltage value used when discharging the secondary battery,
The secondary battery testing device according to claim 1, wherein the protection means includes a protection circuit that generates a voltage according to the discharge setting voltage value. The secondary battery test according to claim 5, further comprising a time measuring unit that measures the time from when the secondary battery starts discharging until the voltage of the secondary battery reaches the discharge setting voltage value. Device. The secondary battery testing device according to claim 3 or 5, wherein the protection circuit includes a Zener diode and a resistor. The set voltage value is a charging set voltage value used when charging the secondary battery and a discharging set voltage value used when discharging the secondary battery,
2. The protective device according to claim 1, wherein the protection means includes a charging protection circuit that generates a voltage according to the charging setting voltage value, and a discharging protection circuit that generates a voltage according to the discharging setting voltage value. The secondary battery testing device described. The time from the start of charging of the secondary battery until the voltage of the secondary battery reaches the set voltage value for charging, and the time from the start of discharging of the secondary battery until the voltage of the secondary battery reaches the set voltage value for charging. The secondary battery testing device according to claim 8, further comprising a time measuring section that measures at least one of the times until the set voltage value for discharge is reached. The secondary battery testing device according to claim 8, wherein the charging protection circuit and the discharging protection circuit are each comprised of a Zener diode and a resistor. The secondary battery testing device according to any one of claims 3 to 6, wherein the protection circuit further includes a current adjustment circuit that adjusts the current flowing through the protection circuit. The charging protection circuit further includes a charging current adjustment circuit that adjusts the current flowing through the charging protection circuit,
The secondary battery testing device according to any one of claims 8 to 10, wherein the discharge protection circuit further includes a discharge current adjustment circuit that adjusts the current flowing through the discharge protection circuit. A secondary battery testing system comprising the secondary battery testing device according to claim 1,
A secondary battery testing system further comprising a management device that manages the operation of the secondary battery testing device.

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