JP6937230B2 - Secondary battery charge / discharge test system - Google Patents

Description

The present invention relates to a charge / discharge test system for a secondary battery, in which, when a secondary battery connected in series is discharged in a fixed quantity, the secondary battery having reached a specified capacity is disconnected from the series connected state without interruption of the discharge current. ..

Conventionally, in the manufacture of a battery (secondary battery), a charge / discharge test of the manufactured battery is performed to inspect whether or not the battery satisfies a predetermined performance and characteristic, and then the battery is shipped.
In the charge / discharge test of this secondary battery, a plurality of secondary batteries connected in series are connected to a power supply for charging / discharging, charged with a predetermined constant current to raise the battery voltage, and the battery voltage reaches a predetermined constant voltage. When it rises, it switches to constant voltage charging to maintain this constant voltage. Then, when a predetermined charging time (or a predetermined ending condition) is reached, the charging operation is terminated and the current is switched to constant current discharge. The constant current discharge is executed at a predetermined constant current (discharge current), and the constant current discharge is terminated when the secondary battery reaches a predetermined specified voltage (or a predetermined end condition) that does not cause over-discharge. However, in constant current discharge, the time until each secondary battery reaches the specified voltage differs depending on the characteristics (rank) of each secondary battery, so the secondary batteries that have reached the specified voltage are sequentially disconnected from the circuit (excluded). There is a need to.
For example, Patent Document 1 describes the output voltage of each cell in an assembled battery evaluation test system that evaluates an assembled battery by performing constant current-constant voltage charge / discharge control on an assembled battery composed of a plurality of cells (batteries). A battery evaluation test device equipped with an exclusion device that accommodates a cell voltage detection line for detecting cells and excludes / connects each cell for each cell, and an output voltage of each cell from each cell voltage detection line. A set consisting of a charge / discharge unit that detects the total voltage of the assembled battery obtained by detecting and summing the detected output voltages, and a control unit that commands the charge / discharge unit to detect the total voltage of the assembled battery. A battery evaluation test system has been proposed.

Japanese Patent No. 3981530

However, in the assembled battery evaluation test system of Patent Document 1, a constant current control that performs the same operation as the above-mentioned conventional charging operation during charging and initially outputs a constant current from the assembled battery evaluation test device during discharging. When the assembled battery evaluation test device cannot maintain the constant current output, the constant current-constant voltage charge / discharge control is performed to shift to the constant current control. Therefore, the exclusion / connection of each cell is switched by the internal switch of the exclusion device, which detects the output voltage of each connected cell and sums the detected output voltages to obtain the total battery voltage. This is to detect and increase or decrease the set current value in response to a change in the total voltage of the assembled battery to perform discharge by constant voltage control.
On the other hand, in constant current discharge, the discharge current is constant, and the discharge capacity of each secondary battery is calculated by integrating the time required for each secondary battery to reach the specified voltage and the current value of the discharge current (constant current). Can be measured. Therefore, even if the secondary battery that has reached the specified voltage is disconnected from the charge / discharge circuit, if a constant discharge current is flowing through the charge / discharge circuit without interruption, the current value at that time is the output current of the charge / discharge power supply. It can be easily measured. For that purpose, a diode is installed in parallel in the direction in which the reverse bias is applied to the secondary battery, and while the secondary battery is discharging (until the specified voltage is reached), a discharge current is passed through the secondary battery to make the diode. When the secondary battery reaches the specified voltage and discharge is completed, make the discharge current flow through the diode and disconnect the secondary battery from the charge / discharge circuit (current flows through the secondary battery). A method of avoiding this) is conceivable.
However, when the voltage of the secondary battery decreases due to the discharge of the secondary battery, due to the influence of the voltage drop such as the characteristics of the diode and the wiring resistance, the diode is forwarded even if the discharge is not completed. A voltage is applied and a minute current flows through the diode. In this state, there is a problem that an error occurs between the current actually flowing through the secondary battery and the current value of the discharge power supply, and the discharge capacity cannot be measured accurately. This tendency becomes remarkable when a Schottky barrier diode is used as the diode to apply the reverse bias.

The present invention has been made in view of such circumstances, and while keeping the discharge current flowing through the charge / discharge circuit constant, the discharged secondary batteries are sequentially separated from the charge / discharge circuit to reduce the discharge capacity of each secondary battery. It is an object of the present invention to provide a charge / discharge test system capable of precise measurement.

The secondary battery charge / discharge test system according to the present invention according to the above object is for current control power supply connected to a plurality of secondary batteries connected in series and for voltage control connected in series to the secondary battery. A charge / discharge power supply that has a bias power supply and forms a charge / discharge circuit,
A series control circuit connected in series for each of the secondary batteries and having a first switching element for disconnecting the secondary battery from the charge / discharge circuit.
A diode connected in parallel to each of the secondary batteries to which the series control circuit is connected in a direction in which a reverse bias is applied, and a second switching element connected in parallel to the diode to form a bypass circuit for the secondary battery. With a parallel control circuit,
By detecting the voltage of each of the secondary batteries,
a) While the discharge of the secondary battery connected to the series control circuit is incomplete, the voltage of the secondary battery being discharged and the amount of voltage drop generated in the line connected to the secondary battery The voltage applied to the diode due to the difference is lower than the voltage at which the current starts to flow in the diode, and the discharge of the secondary battery is maintained.
b) When the voltage of the secondary battery reaches the specified voltage and the discharge is completed, the first switching element is turned off to disconnect the secondary battery from the charge / discharge circuit, and at the same time, a current starts to flow in the diode. ,
c) Further, an individual control means for turning on the second switching element and sequentially performing an operation of flowing the discharge current of the charge / discharge circuit to the bypass circuit is provided .
Wherein the parallel control circuit, it is connected is adjusted diode in a direction reverse bias is applied to the diode in series.

In the charge / discharge test system for a secondary battery according to the present invention, the amount of voltage drop generated in the line connected to the secondary battery is preferably defined by the wiring resistance of the line.

In the charge / discharge test system for the secondary battery according to the present invention, the first and second switching elements are preferably semiconductor elements.

The secondary battery charge / discharge test system according to the present invention includes a current control power supply connected to a plurality of secondary batteries connected in series, and a voltage control bias power supply connected in series to the secondary battery. Since it has a charge / discharge power supply that forms a charge / discharge circuit, it is possible to reliably flow a discharge current until the voltage of the secondary battery reaches the specified voltage, and the secondary battery that has been discharged is separated from the charge / discharge circuit. Even if the voltage fluctuates, it is possible to suppress the fluctuation of the discharge current and keep the discharge current flowing stably, and it is possible to improve the accuracy of the discharge capacity measurement.
A series control circuit that is connected in series for each secondary battery and has a first switching element for disconnecting the secondary battery from the charge / discharge circuit, and a direction in which a reverse bias is applied to each secondary battery to which the series control circuit is connected. It is equipped with a parallel control circuit having a diode connected in parallel to the capacitor and a second switching element connected in parallel to the diode to form a bypass circuit for the secondary battery, and the voltage of each secondary battery is controlled by individual control means. While the secondary battery connected to the series control circuit is not completely discharged (until the voltage reaches the specified voltage), the voltage of the secondary battery being discharged and the line connected to the secondary battery are displayed. The voltage applied to the diode due to the difference from the generated voltage drop is lower than the voltage at which the current starts to flow in the diode, and the discharge of the secondary battery can be maintained. As a result, no current flows through the diode during discharge, and a constant discharge current can continue to flow until the voltage of the secondary battery reaches the specified voltage (almost 0 V), and the time until discharge is completed and the discharge current. Accurate discharge capacity can be measured by integrating the current values of. When the voltage of the secondary battery reaches the specified voltage and the discharge is completed, the first switching element is turned off to disconnect the discharged secondary battery from the charge / discharge circuit, and at the same time, current starts to flow in the diode. By turning on the second switching element and letting the discharge current of the charge / discharge circuit flow through the bypass circuit, the discharge current flowing through the charge / discharge circuit is not interrupted, and the heat generation of the diode can be minimized. In this way, the secondary batteries that have been discharged are sequentially separated from the charge / discharge circuit, and even if the number of secondary batteries connected to the charge / discharge circuit decreases, a constant discharge current can continue to flow. It is possible to measure the discharge capacity of all secondary batteries with high accuracy.

When the amount of voltage drop generated in the line connected to the secondary battery is specified by the wiring resistance of the line, the optimum amount of voltage drop according to the characteristics of the diode can be easily set, and the secondary battery is being discharged. No current flows through the diode, the fluctuation of the discharge current flowing through the secondary battery can be prevented, and the measurement error of the discharge capacity can be suppressed.
The parallel control circuit, since the direction in which the reverse-biased diode in series with the adjustment diode is connected, Ki de is possible to increase the voltage current starts flowing to the parallel control circuit (diode), correspondingly, the secondary The line connected to the battery can be lengthened (wiring resistance can be increased), increasing the degree of freedom in circuit design.
When the first and second switching elements are semiconductor elements, the response speed of switching can be adjusted, and the discharge current can be adjusted by combining the current control power supply and the charge / discharge power supply provided with the voltage control bias power supply. It is possible to effectively prevent fluctuations in the discharge capacity and improve the reliability of discharge capacity measurement.

It is explanatory drawing which shows the structure of the charge / discharge test system of the secondary battery which concerns on one Embodiment of this invention. It is explanatory drawing which shows the operation of the charge / discharge test system of the secondary battery. It is explanatory drawing which shows the modification of the parallel control circuit of the charge / discharge test system of the secondary battery.

Subsequently, an embodiment embodying the present invention will be described with reference to the attached drawings, and the present invention will be understood. As shown in FIGS. 1 and 2, the secondary battery charge / discharge test system 10 according to the embodiment of the present invention discharges a plurality of secondary batteries 12 connected in series to the charge / discharge circuit 11 at a constant current. Even if the secondary batteries 12 that have reached the specified voltage (for example, 0 V) and have been discharged are disconnected from the series connection state, the discharge current I flowing through the charge / discharge circuit 11 is not interrupted, and the secondary batteries 12 of each secondary battery 12 are not interrupted. The discharge capacity can be measured accurately.
Hereinafter, the details of the charge / discharge test system 10 for the secondary battery will be described.
First, as shown in FIG. 1, in the secondary battery charge / discharge test system 10, a plurality of secondary batteries 12 are connected in series to the charge / discharge circuit 11 to perform a test at the same time. The charge / discharge power supply 13 forming the charge / discharge circuit 11 is a current control power supply 14 connected to a plurality of secondary batteries 12 connected in series, and a voltage control bias power supply connected in series to the secondary battery 12. It has 15. As the current control power supply 14, one using a swing choke coil is preferably used. As a result, the influence of the ripple current at the time of a minute current can be reduced, and a minute current to a large current can be accurately flowed. Further, the voltage control bias power supply 15 is a power supply that gives an offset voltage to the secondary battery 12 so that the secondary battery 12 can be discharged to a specified voltage (for example, 0 V) even if the voltage of the secondary battery 12 becomes low. Is. The number of secondary batteries 12 to be tested connected in series is not particularly limited.

Next, a series control circuit 16 is connected in series for each secondary battery 12, and the series control circuit 16 has a first switching element 17 for disconnecting the secondary battery 12 from the charge / discharge circuit 11. ing. In the present embodiment, the power MOSFET, which is a semiconductor element, is used as the first switching element 17, but the present invention is not limited to this. Although the diode 18 is shown in FIG. 1, it represents a parasitic diode (body diode) existing inside the power MOSFET, and since it is not an essential configuration, there is no parasitic diode inside. When using a switching element, it is not necessary to connect a diode separately.
Further, a parallel control circuit 20 is connected to each secondary battery 12 to which the series control circuit 16 is connected, and the parallel control circuit 20 is a diode connected in parallel with the secondary battery 12 in the direction in which the reverse bias is applied. It has a second switching element 22 connected in parallel to the 21 and the diode 21 to form a bypass circuit for the secondary battery 12. The second switching element 22 can be appropriately selected, but a semiconductor element is preferably used. Further, as the diode 21, a rectifying diode is preferably used. The rectifying diode has a smaller leakage current than the Schottky barrier diode, can eliminate the influence of the diversion, and can maintain the discharge current I flowing through the secondary battery 12 with high accuracy. When a power MOSFET is used as the second switching element 22, a parasitic diode (body diode) existing inside the power MOSFET is used for the diode 21, so that it is not necessary to separately connect a diode.

The secondary battery charge / discharge test system 10 has an individual control means 25 that controls charge / discharge for each secondary battery 12. The individual control means 25 measures the voltage of the secondary battery 12 being discharged and compares it with a preset specified value (specified voltage, for example, 0 V), and the comparator 26 and the secondary battery 12 measured by the comparator 26. It has a driver 27 for switching on / off of the first and second switching elements 17 and 22 according to the voltage of.
The discharge test is started after the second switching element 22 is turned off and the first switching element 17 is turned on when the secondary battery 12 is fully charged.
Here, since the diode 21 is connected in parallel with respect to the secondary battery 12 in the direction in which the reverse bias is applied, the diode 21 may be subjected to the forward voltage while the voltage of the secondary battery 12 is high. No current flows through the diode 21.

However, a wiring resistor 29 exists in the line 28 connected to the secondary battery 12, and a voltage drop occurs due to the flow of the discharge current I. Therefore, the difference between the voltage of the secondary battery 12 being discharged and the amount of voltage drop generated in the line 28 connected to the secondary battery 12 is the voltage applied to both ends of the diode 21. Therefore, when the voltage of the secondary battery 12 drops with the discharge, the amount of voltage drop generated on the line 28 becomes larger than the voltage of the secondary battery 12 at a certain point, and the voltage on the diode 21 is negative, that is, in the forward direction. The voltage will be applied. Then, when the voltage in the forward direction becomes larger than a certain value, a current starts to flow in the diode 21, and the discharge current flowing in the secondary battery 12 fluctuates.
Therefore, the wiring resistor 29 is set so that the voltage applied to the diode 21 becomes lower than the voltage at which the current starts to flow in the diode 21 until the voltage of the secondary battery 12 being discharged reaches the specified voltage (until the discharge is completed). By specifying, even if the voltage of the secondary battery 12 becomes low due to the discharge, the discharge of the secondary battery 12 can be maintained at a constant current until the discharge is completed without passing a current through the diode 21.

For example, when the forward voltage at which the current starts to flow in the diode 21 is 0.2 V, the wiring resistance 29 is set so that the amount of voltage drop generated in the line 28 is lower than 0.2 V, and the secondary battery 12 If the first switching element 17 is turned off when the voltage of the secondary battery 12 becomes 0V, a current starts to flow in the diode 21 at that time. Can be maintained. Therefore, when the voltage of the secondary battery 12 measured by the comparator 26 becomes almost 0 V, it is determined that the discharge is completed, and the first switching element 17 is turned off by the command from the driver 27. The next battery 12 is disconnected from the charge / discharge circuit 11. Then, as soon as the secondary battery 12 that has been discharged is disconnected from the charge / discharge circuit 11, a current starts to flow in the diode 21, and the discharge current I continues to flow in the charge / discharge circuit 11 through the diode 21. Fluctuations can be prevented. Next, by turning on the second switching element 22 by a command from the driver 27, the discharge current I flowing through the diode 21 is charged and discharged through the bypass circuit side formed by the second switching element 22. Continues to flow through circuit 11. At this time, the on-resistance of the second switching element 22 is small, and heat generation can be minimized. In FIG. 2, the time (T2-T1) from turning off the first switching element 17 to turning on the second switching element 22 can be appropriately selected, but is about several msec. preferable.
Here, when the line 28 connected to the secondary battery 12 becomes long and the wiring resistance 29 becomes large, an adjustment diode is additionally connected in the direction in which the reverse bias is applied in series with the diode 21, and the wiring resistance 29 is used. By offsetting the amount of voltage drop, the secondary battery 12 can be discharged until the voltage becomes almost 0 V. As shown in the modified example of FIG. 3, if a power MOSFET is added as an additional switching element 22a in the parallel control circuit 20a, the parasitic diode (body diode) existing inside the power MOSFET is used as the adjustment diode 30. Therefore, it is not necessary to connect a diode separately.

As described above, according to the charge / discharge test system 10 of the secondary battery, the secondary battery 12 starts discharging, the discharging is completed at time T1, the first switching element 17 is turned off, and the secondary battery 12 A constant discharge current I (output current of the charge / discharge power supply 13) flows through the secondary battery 12 until the battery 12 is disconnected from the charge / discharge circuit 11. Therefore, as shown in FIG. 1, the discharge current I and each secondary battery 12 start discharging by the charging / discharging power supply 13 and the controller 31 connected to each individual control means 25 until the discharge is completed. By measuring the time T1 and integrating the discharge current I and the time T1, the discharge capacity of each secondary battery 12 can be measured accurately. At this time, the discharge current I flowing through the charge / discharge circuit 11 is maintained constant regardless of the number of connected secondary batteries 12, so that the discharge time (T1) depends on the characteristics (rank) of each secondary battery 12. Even if they are different, the discharge capacity of each can be accurately obtained, and a plurality of secondary batteries 12 can be tested and sorted in a short time.
The discharge energy discharged from the secondary battery 12 can be regenerated into a commercial AC power source for effective use, reducing power consumption and reducing the cost of the test. At this time, the voltage of the secondary battery 12 decreases with the discharge, but by using the boost chopper circuit, it is possible to maintain a high voltage output and efficiently regenerate the power.

Although the embodiment of the present invention has been described above, the present invention is not limited to the configuration described in the above-described embodiment, and can be considered within the scope of the matters described in the claims. Other embodiments and modifications are also included.
The secondary battery tested by the secondary battery charge / discharge test system 10 is mainly a nickel hydrogen battery, but other secondary batteries such as a lithium battery and a lead battery can also be targeted.

10: Secondary battery charge / discharge test system, 11: Charge / discharge circuit, 12: Secondary battery, 13: Charge / discharge power supply, 14: Current control power supply, 15: Voltage control bias power supply, 16: Series control circuit , 17: 1st switching element, 18: diode, 20, 20a: parallel control circuit, 21: diode, 22: second switching element, 22a: additional switching element, 25: individual control means, 26: comparator, 27: Driver, 28: Line, 29: Wiring resistance, 30: Adjustment diode, 31: Controller

Claims (3)

A charge / discharge power supply that includes a current control power supply connected to a plurality of secondary batteries connected in series and a voltage control bias power supply connected in series to the secondary batteries to form a charge / discharge circuit.
A series control circuit connected in series for each of the secondary batteries and having a first switching element for disconnecting the secondary battery from the charge / discharge circuit.
A diode connected in parallel to each of the secondary batteries to which the series control circuit is connected in a direction in which a reverse bias is applied, and a second switching element connected in parallel to the diode to form a bypass circuit for the secondary battery. With a parallel control circuit,
By detecting the voltage of each of the secondary batteries,
a) While the discharge of the secondary battery connected to the series control circuit is incomplete, the voltage of the secondary battery being discharged and the amount of voltage drop generated in the line connected to the secondary battery The voltage applied to the diode due to the difference is lower than the voltage at which the current starts to flow in the diode, and the discharge of the secondary battery is maintained.
b) When the voltage of the secondary battery reaches the specified voltage and the discharge is completed, the first switching element is turned off to disconnect the secondary battery from the charge / discharge circuit, and at the same time, a current starts to flow in the diode. ,
c) Further, an individual control means for turning on the second switching element and sequentially performing an operation of flowing the discharge current of the charge / discharge circuit to the bypass circuit is provided .
Wherein the parallel control circuit, the charge-discharge test system for a secondary battery said diode in series to the adjustment diode reverse biased direction, characterized that it is connected. In the secondary battery charge / discharge test system according to claim 1, the amount of voltage drop generated in the line connected to the secondary battery is defined by the wiring resistance of the line. Charge / discharge test system. The charge / discharge test system for a secondary battery according to claim 1 or 2, wherein the first and second switching elements are semiconductor elements.

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