JP2013029485A - Charging and discharging test device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging and discharging test device in which, when charging and discharging tests of individual secondary batteries are performed, the tests can be done at low power consumption.SOLUTION: A charging and discharging test device comprises: switches 2a to 2d for arbitrarily switching a circuit which charges, discharges or bypasses a secondary battery 1; a switching control part 3 for performing an ON-OFF control of the switches 2a to 2d; a power supply device 5 for charging or discharging the secondary battery 1; and a series circuit which is obtained by serially connecting a plurality of units and the power supply device 5 after forming the secondary battery 1, the switches 2a to 2d and the switching control part as one unit.

Description

  The present invention relates to a charge / discharge test apparatus that charges or discharges a secondary battery and performs activation or performance test of the secondary battery.

  In recent years, secondary batteries such as rechargeable lithium-ion batteries have been widely used in various electrical and electronic devices. In addition, due to problems such as environmental protection and the depletion of petroleum resources, the range of use, such as electric vehicles using secondary batteries as a drive source, has been expanding. For this reason, technological development of secondary batteries is progressing rapidly, and improvements in energy density, miniaturization, weight reduction, long life, and the like are being achieved. On the other hand, the manufacturing process is required to have very high processing accuracy, and it is important to ensure reliability. In general, a single battery, such as a lithium ion battery, has a low output voltage value and its use is limited. Therefore, in order to ensure high output, a lithium battery may be used in a state of an assembled battery in which unit cells are combined in series. In many cases, in the charge / discharge test at the time of battery manufacture, even if one battery in the assembled battery becomes defective, the performance of the entire assembled battery is affected. Therefore, every battery is inspected. In addition, such a secondary battery needs to activate an internal electrode after assembling, and for this purpose, a plurality of charge / discharge tests are performed on each battery.

  In the activation and performance inspection of the secondary battery, it is necessary to charge / discharge the single cell with an arbitrary current, and there are serial charging, parallel charging, single charging and the like as charging methods. Lithium ion batteries are vulnerable to overcharge and overdischarge, and if used within a specified voltage range, their capacity will be reduced and abnormal heat will be generated. When charging / discharging an assembled battery in which single cells are arranged in series, monitor the voltage of each single cell, and if there is a difference in the voltage balance between single cells, Charging that balances the voltage between the batteries by bypassing the battery and not charging / discharging (for example, see Patent Document 1), or by temporarily suspending charging and discharging a high-voltage unit cell with a resistor or current control circuit. Although there is a discharge method (for example, refer to Patent Document 2), in the charge / discharge test at the time of battery manufacture, there is a large variation in battery performance, so series charging is not used. Also, the parallel charging is not used because the efficiency is greatly reduced because the current is increased while the voltage is low. Currently, single charge is the mainstream in charge and discharge tests during battery production. In addition, when a battery is discharged alone, it may not be sufficiently discharged due to the influence of the internal resistance of the battery or the wiring resistance of the circuit, and a method of providing a bias voltage for discharging in order to avoid this (for example, patent documents) 3).

JP-A-7-163060 JP-A-8-0119188 JP-A-10-191571

  In the inspection of a secondary battery in a mass production factory, charging / discharging is repeatedly performed for a large number of secondary batteries, so that the power consumption used for the charge / discharge test also increases. However, in the current mainstream charge / discharge test equipment using single charge / discharge, the discharge power is not reused but converted to thermal energy or the like, or it is necessary to provide a bias power supply to further discharge to a predetermined voltage value. There was a problem that power use efficiency was bad.

  Then, an object of this invention is to provide the charging / discharging test apparatus which can test by low power consumption in performing the charging / discharging test of each secondary battery.

  In order to achieve the above object, the charge / discharge test apparatus of the present invention comprises a switching means for arbitrarily switching a circuit for charging, discharging or bypassing a secondary battery, a switching control means for controlling on / off of the switching means, A power source for charging or discharging a secondary battery, the secondary battery, the switching unit, and the switching control unit are set as one unit, and a plurality of the units and the power source are connected in series to form a series circuit. Features. The switching means includes a first switch and a second switch connected in parallel from one of the two connection points of the series circuit and the unit, and the other connection point. A third switch and a fourth switch connected in parallel; the other end of the first switch and the third switch is connected to the positive electrode of the secondary battery; the second switch and the fourth switch; The other end of the switch is connected to the negative electrode of the secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, the charging / discharging test apparatus which can test with low power consumption can be provided in performing the charging / discharging test of each secondary battery.

The figure which showed the whole structure of 1st embodiment of the charging / discharging test apparatus concerning this invention. The figure which showed the unit 4 in detail. The figure explaining that the charging / discharging test apparatus of embodiment of this invention reduces power consumption and improves efficiency. The graph which showed the relationship between voltage V2 and efficiency (eta). The figure explaining that the charging / discharging test apparatus of embodiment of this invention reduces power consumption and improves efficiency. The figure which added bias power supply C2. The figure which connected the battery B1 of the terminal voltage V2 and the battery B2 of the terminal voltage V3 in series with the polarity reversed. The figure which shows the case where battery B1 and battery B2 are a plurality of serial connection. The figure which prepared the apparatus which controls start time outside.

  Hereinafter, embodiments of a charge / discharge test apparatus according to the present invention will be described with reference to the drawings. 1 to 9 show examples of embodiments for carrying out the present invention, and the present invention is not limited by these drawings. FIG. 1 is a diagram showing an overall configuration of a first embodiment of a charge / discharge test apparatus according to the present invention. A switch 2 (2a to 2d), which is a switching means, is connected to the secondary battery 1 that is the subject of the charge / discharge test. Further, there is a switching control unit 3 for giving a command for turning on / off the switch, and a unit 4 (4a, 4b,...) Having the secondary battery 1, the switches 2a to 2d, and the switching control unit 3 as one unit. 4n) is connected in series by the number of secondary batteries 1 to be tested, and further, a power supply device 5 that charges and discharges the secondary battery 1 is connected in series.

  The switches 2 a to 2 d are switching elements such as transistors, for example, and perform an on / off operation according to a command from the switching control unit 3. Here, the switch 2a and the switch 2b are connected in parallel from the connection point between the plus side of the power supply device 5 on the series circuit and the unit 4a, and the switch 2c and the switch 2d are connected to the minus side of the power supply device 5 on the series circuit and the unit. The other ends of the switch 2a and the switch 2c are connected to the positive electrode of the secondary battery 1, and the other ends of the switch 2b and the switch 2d are connected to the negative electrode of the secondary battery 1. ing. With such a configuration, it is possible to configure a circuit that charges, discharges, and bypasses the secondary battery 1 by a combination of ON / OFF of the switches 2a to 2d.

  To make the charging circuit, the switches 2a and 2d are turned on and the switches 2b and 2c are turned off, and the secondary battery 1 is connected to the series circuit in the charging direction.

  To make the discharge circuit, the switches 2b and 2c are turned on and the switches 2a and 2d are turned off, and the secondary battery 1 is connected to the series circuit in the discharge direction.

  In order to obtain a bypass circuit, the switches 2b and 2d are turned on, the switches 2a and 2c are turned off, or the switches 2a and 2c are turned on and the switches 2b and 2d are turned off. In this state, the secondary battery 1 can be freely attached and detached regardless of whether the entire circuit is energized.

  Thus, the charging circuit, discharging circuit, or bypass circuit of the secondary battery 1 can be arbitrarily implemented without interrupting the entire series circuit.

  FIG. 2 is a diagram showing the unit 4 in detail, and the same or corresponding parts as those in FIG. The switches 2a to 2d represent cases where transistors are used as switching elements. Moreover, it is comprised from the ammeter 11 which measures the electric current which flows into the secondary battery 1, the voltmeter V1 which measures the voltage of the secondary battery 1, and the switching control part 3 which controls on / off of switch 2a-2d. The switching control unit 3 is constituted by a personal computer, a microcomputer, or the like including a central processing unit, a memory, and the like, and can give on / off commands to the switches 2a to 2d, and can arbitrarily charge, discharge, and bypass circuits. Or it has the function which can switch the electric current value and voltage value of the secondary battery 1 on condition. Furthermore, the switching control unit 3 can arbitrarily control the current flowing through the secondary battery 1 by performing PWM control on the switches 2c and 2d.

  In the charging mode, by turning on only the switches 2a and 2d, the secondary battery 1 can be connected to the series circuit in the charging direction. When controlling the charging current, the switch 2a is always turned on, and the switch 2d is turned on / off by constant current PWM control so that the current flowing through the secondary battery 1 has a predetermined current value. If the switch 2d is turned off at this time, the entire series circuit is cut off. Therefore, by setting the switch 2c to an operation state opposite to that of the switch 2d, the secondary battery 1 is bypassed by the switch 2a and the switch 2c and the whole series circuit is cut off. Do not.

  In the discharge mode, the secondary battery 1 can be connected to the series circuit in the discharge direction by turning on only the switches 2b and 2c. When controlling the discharge current, the switch 2b is always turned on, and the switch 2c is turned on / off by constant current PWM control so that the current flowing through the secondary battery 1 has a predetermined current value. If the switch 2c is turned off at this time, the entire series circuit is cut off. Therefore, by setting the switch 2d to the operation state opposite to the switch 2c, the secondary battery 1 is bypassed by the switch 2b and the switch 2d and the whole series circuit is cut off. Do not.

  Note that a reactor L1 and a capacitor C1 are provided to prevent pulsation due to switching during the constant current PWM control.

  The switching control unit 3 performs the following control based on the information on the current I1 and the voltage V1, and performs various charge / discharge tests and prevention of overcharge / overdischarge on the secondary battery 1.

<CC charge, CC discharge>
The current I1 flowing through the secondary battery 1 during charging or discharging is kept constant by PWM control.
<CCCV charging>
When the voltage V1 of the secondary battery 1 is equal to or lower than the specified voltage, CC charging is performed, and when the voltage V1 becomes equal to or higher than the specified voltage, the charging current is controlled to become the specified voltage. When the charging current becomes less than the specified current, CCCV charging is stopped.
<CCCV discharge>
When the voltage V1 of the secondary battery 1 is equal to or higher than the specified voltage, CC discharge is performed, and the discharge current is controlled so as to become the specified voltage when the voltage is equal to or lower than the specified voltage. When the discharge current becomes less than the specified current, the CCCV discharge is stopped.
<CP charge, CP discharge>
The current I1 is PWM controlled so that the charging power or discharging power to the secondary battery 1 is constant. At this time, the charging power to the secondary battery 1 is obtained by I1 × V1.
<Abnormal voltage monitoring>
When the voltage V1 of the secondary battery 1 exceeds the upper limit or less than the lower limit, charging / discharging is stopped and the secondary battery 1 is protected.

  Next, the principle by which the charge / discharge test apparatus in the embodiment of the present invention reduces power consumption and improves efficiency will be described with reference to FIGS.

One of the problems associated with the charge / discharge test apparatus is a decrease in charge efficiency during low-voltage charge / discharge. Referring to FIG. 3, consider the case where the secondary battery B1 of voltage V2 is charged by the power supply device C1. Necessary when the current I is passed through the circuit, assuming that the loss resistance on the circuit, such as the wiring resistance of the circuit, the internal resistance of the secondary battery B1, and the switching loss of the power supply C1, is equivalent to the loss resistance R. The output voltage V1 of the power supply device C1 is
V1 = V2 + I · R (1)
Thus, the supplied power P1 from the power supply device C1 is
P1 = V1 · I (2)
The injection power P2 to the secondary battery B1 is
P2 = V2 · I (3)
The charging efficiency η is
η = P2 / P1 = V2 / I / V1 · I = V2 / (V2 + I · R) (4)
It becomes. This relational expression also applies to discharge.

  The relationship between the voltage V2 and the efficiency η when charging / discharging at 10A, 20A, and 50A is assumed to be 100 mΩ, assuming that the loss resistance R in the formula (4) is 100 mΩ, is shown in FIG. It turns out that falls. Thereby, since the voltage of the single charge of a lithium secondary battery is as low as 2-4V, it turns out that it is used in the voltage area | region where efficiency is low.

  As described above, when the output voltage is low as in the lithium secondary battery, there is a problem that the charge / discharge efficiency is deteriorated in the single charge method, and the charge / discharge is increased by increasing the battery voltage as shown in the equation (4). It turns out that the efficiency of. On the other hand, the secondary battery can be connected in series to increase the battery voltage, but in the secondary battery test and inspection, the number of series cannot be fixed as in the assembled battery, and it is free from the series circuit individually. It is required to be removable.

  In the charge / discharge test apparatus according to the embodiment of the present invention, as means for this purpose, switches 2a to 2d are provided inside the units 4a to 4n as shown in FIGS. When only the switches 2b and 2d are turned on or only the switches 2a and 2c are turned on, no current flows through the secondary battery 1, so the secondary battery 1 can be freely attached and detached. When there are a plurality of units 1 in which only the switches 2a and 2d are turned on, the internal secondary battery 1 is connected in series, and the voltage V2 shown in FIG. 4 is increased so that the charging efficiency can be improved. Become.

Another problem with the charge / discharge test apparatus is that a bias power supply is required when discharging at a low voltage and a large current. FIG. 5 is a diagram illustrating a case where the secondary battery B1 having the voltage V2 is discharged with the current I using the electronic load D1. The term “electronic load” as used herein means that the resistance value inside the electronic load can be varied so that a specified current flows in the circuit. If the loss resistance on the circuit is R, the voltage V1 across the electronic load D1 is
V1 = V2-I · R (5)
It becomes. In order to discharge only with the energy of the battery, it is necessary that V1> 0. However, due to the recent high performance of the secondary battery, the discharge current has become extremely large. It is necessary. When I increases, the right side of equation (5) may become negative, and at this time, it becomes impossible to discharge only with the energy of the battery. For this reason, as shown in FIG. 6, the bias power supply C2 is added to force the current to flow in the discharge direction. FIG. 6 is a diagram showing a circuit in which the bias power source C2 is provided in the circuit of FIG. 5. When discharging with a large current in this way, there is a problem that it is necessary to supply power for the bias power source C2 even during discharging.

  Thus, there is a problem that the power consumption is increased by using a bias power source for discharging with a large current. To deal with this, as shown in FIG. 7, the battery B1 having the terminal voltage V2 and the terminal voltage V3 have a problem. A case where the battery B2 is connected in series with the polarity reversed may be considered.

The output voltage V1 of the power supply device 2 required when the current I is supplied to this circuit is
V1 = V2 + I · R−V3 (6)
Thus, the supplied power P1 from the power supply device 2 is
P1 = I · V1 = I · (V2 + I · R-V3) = I 2 · R + I (V2-V3) ... (7)
It becomes. When V2 = V3, the supply power P1 in the equation (7) is I ² · R, and only the power consumed by the loss resistor R needs to be supplied.

  In cases other than V2 = V3, it goes without saying that the power supply P1 of the equation (7) can be reduced, and in the state of (V2 + I · R) <V3, P1 is negative, but the power supply C1 is Regeneration to the power supply system can be performed by using a regenerative power source. As shown in FIG. 8, Expression (7) also holds when the battery B1 and the battery B2 are connected in series.

  In the charge / discharge test apparatus according to the embodiment of the present invention, the connection direction of the secondary battery 1 can be reversed by the switches 2a to 2d of the units 4a to 4n connected in series. 7, the state shown in FIG. 8 is obtained, and the power supplied from the power supply device 5 can be reduced as shown by the equation (7). If a regenerative power source is used for the power supply device 5, regeneration to the power system can be performed in a state of (V2 + I · R) <V3.

  Furthermore, another problem concerning the charge / discharge test apparatus is that each cell needs to be controlled with a different current even when connected in series. This is because it is necessary to test at various current values in the charge / discharge test of the secondary battery. As a means for solving this problem, in the embodiment of the present invention, the switch 2c or the switch 2d of the units 4a to 4n connected in series is PWM-controlled to a designated current. Further, the switch 2c and the switch 2d are operated in reverse to prevent the entire series circuit from being cut off. The power supply device 5 may constantly monitor the charge / discharge scheduled currents of the units 4a to 4n and flow the maximum current through the series circuit. It should be noted that this may be achieved by adding all the components that take in all the current values flowing through the secondary batteries of each unit and determine the maximum current.

  According to the present invention, each cell can be charged / discharged with an arbitrary current, and a battery cell that has been inspected can be freely detached, so that the working efficiency can be improved. In addition, the efficiency when using all the batteries in the charge mode or the discharge mode is improved in proportion to the increase of the voltage V2 due to the series connection as shown in the equation (3). Electric power can be reduced.

  When the charging mode and the discharging mode coexist, the power supplied from the power supply device 5 is reduced as shown by the equation (7). Therefore, there is an effect of reducing the power consumed by charging and discharging by two methods of improving efficiency by increasing the voltage by series connection and using voltage energy at the time of discharging as energy at the time of charging. In the performance test at the time of battery development, the same battery has been charged and discharged several hundred times, and in the battery production plant, it is necessary to charge and discharge for battery activation and performance test. Yes, both consume a lot of power. If the present invention is applied to these, power consumption can be greatly reduced.

  As shown in FIG. 9, in the charge / discharge inspection in which there is no restriction on the start time of charge / discharge, an external device for controlling the start time is prepared, and each single cell is set so that the number of batteries for charge and discharge is approximately the same. By controlling the charge / discharge start time of the battery, power consumption can be efficiently reduced.

  In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

  DESCRIPTION OF SYMBOLS 1 ... Secondary battery, 2 ... Switch, 3 ... Switching control part, 4 ... Unit, 5 ... Power supply device, I1 ... Ammeter, V1 ... Voltmeter

Claims (7)

Switching means for arbitrarily switching a circuit for charging, discharging or bypassing the secondary battery; and switching control means for controlling on / off of the switching means;
A power source for charging or discharging the secondary battery;
The charge / discharge test apparatus according to claim 1, wherein the secondary battery, the switching unit, and the switching control unit are one unit, and a plurality of the units and the power source are connected in series to form a series circuit. The switching means includes two connection points between the series circuit and the unit.
A first switch and a second switch connected in parallel from one of the connection points;
A third switch and a fourth switch connected in parallel from the other connection point;
The other ends of the first switch and the third switch are connected to the positive electrode of the secondary battery, and the other ends of the second switch and the fourth switch are connected to the negative electrode of the secondary battery. The charge / discharge test apparatus according to claim 1.   3. The secondary battery can be detached from the charge / discharge test apparatus while the series circuit is energized by using a circuit that bypasses the secondary battery by the switching unit. 4. Charge / discharge test equipment.   The predetermined unit of the plurality of units is charged by the switching unit, and another predetermined unit is discharged by the switching unit, and charging and discharging are performed simultaneously. Item 4. The charge / discharge test apparatus according to any one of Items 3 to 3.   5. The unit according to claim 1, wherein the unit further includes a voltage measuring unit that measures a voltage of the secondary battery, and inputs the measured voltage value to the switching control unit. The charge / discharge test apparatus as described.   The unit further includes a current measuring unit that measures a current flowing through the secondary battery, and inputs the measured current value to the switching control unit. The switching control unit is configured so that a current flowing through the secondary battery is a predetermined value. The charge / discharge test apparatus according to any one of claims 1 to 5, wherein the switching unit is subjected to PMW control so as to obtain a current value.   The charge / discharge test apparatus according to any one of claims 1 to 6, wherein the power source is a regenerative power source.

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