JP2015227803A - Secondary battery internal resistance measurement device and measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact and power saving secondary battery internal resistance measurement device and measurement method that measure internal resistance of a multi-cell unit type battery composed of a plurality of secondary batteries.SOLUTION: A contact c of switches 3-1a and 3-1b of a switcher 3-1 is connected to a contact b and a contact c of switches 3-2a and 3-2b of a switcher 3-2 is connected to a contact a, and thereby a secondary battery 4-1 is put into a discharge state, and a secondary battery 4-2 is put into a charge state. In this instance, the secondary battery 4-1 is configured to function as a DC power for charging the secondary battery 4-2, and a discharge current from the secondary battery 4-1 is utilized as a discharge current to the secondary battery 4-2. Further, the switches 3-1 and 3-2 are switched, and thereby, the secondary battery 4-2 is configured to function as a DC current for charging the secondary battery 4-1, and a discharge current from the secondary battery 4-2 is utilized as a charge current to the secondary battery 4-1.

Description

  The present invention relates to a secondary battery internal resistance measuring device and a measuring method for measuring internal resistance of a multi-cell unit type battery in which a plurality of secondary batteries are combined.

  Rechargeable batteries such as lithium batteries mounted on hybrid vehicles (HV), plug-in hybrid vehicles (PHV), and electric vehicles (EV) are the interior of the secondary battery according to the test method (performance requirements) defined by the IEC62660-1 standard. It is necessary to measure resistance. FIG. 8 shows a test order for measuring the internal resistance of the secondary battery defined by the IEC62660-1 standard. The secondary battery internal resistance measuring device controls the secondary battery to be measured to gradually increase the charge / discharge amount while alternately repeating discharge and charge at a constant time interval.

  FIG. 9A shows a configuration of a prior art secondary battery internal resistance measuring device, and FIG. 9B shows a schematic diagram thereof. One terminal of the constant current control circuit 22 is connected to the positive electrode of the DC power supply 21, and the negative electrode of the DC power supply 21 and the other terminal of the constant current control circuit 22 are connected to the switch 23, via the switch 23. Connected to the secondary battery 24. The switch 23 includes two switches 23 a and 23 b that switch the connection between the positive electrode and the negative electrode of the secondary battery 24. In addition, a voltmeter 25 is installed so that the voltage of the secondary battery 24 can be measured.

  9A and 9B show that the secondary battery is in a charged state. At this time, the contacts c of the switches 23a and 23b of the switch 23 are connected to the contact a. In order to discharge the secondary battery 24, the contacts c of the switches 23a and 23b of the switch 23 are connected to the contact b, respectively.

  FIG. 10A shows a discharge state of the prior art secondary battery internal resistance measuring device, and FIG. 10B shows a schematic diagram thereof. Arrows indicate the direction of current.

  As can be seen from the comparison between FIG. 9B and FIG. 10B, the direction of the charging current to the secondary battery and the direction of the discharging current from the secondary battery are reversed. Sometimes, the direction (polarity) of the secondary battery viewed from the constant current control circuit 22 is reversed. FIG. 11 shows the discharge current viewed from the secondary battery and the direction of the charge current.

  Currently, with the increase in output of PHV and EV, in order to secure a large amount of power, multi-cell unit type batteries in which tens or hundreds of single-cell secondary batteries are generally combined in series and in parallel are used. Yes. In such a usage mode, the importance of a technique for appropriately grasping the current state of the battery is increasing even under conditions in which charging and discharging change dynamically, and the large current of a multi-cell unit battery in the EV field is increasing. Testing at is required.

FIG. 12 shows a configuration of an internal resistance measuring device for a multi-cell unit type battery according to the prior art. The prior art secondary battery internal resistance measuring device depends on the number of single-cell secondary batteries connected in series, and the test voltage increases as the number increases. For example, when four secondary batteries having a single cell rated voltage of 50 volts are connected in series, a test voltage of 200 volts is required from the following formula.
Vt = Vc × n
(Vt: test voltage, Vc: rated voltage of single cell, n: number of secondary batteries connected in series)

  In order to cope with the high voltage of such a large-capacity multi-cell unit type battery, it is also necessary to increase the size of the charge / discharge power supply device including the DC power source and the constant current control circuit of the secondary battery internal resistance measuring device.

JP 2003-121516 A

However, as a result, the following problems occur in the conventional technique.
(1) The DC power supply 21 and the constant current control circuit 22 are increased in size, increasing the power consumption and the weight of the entire apparatus.
(2) The DC power supply 21 and the constant current control circuit 22 are expensive.
(3) Increase in the weight of the DC power supply 21 and the constant current control circuit 22 makes it difficult to move.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a small and power-saving secondary battery for measuring the internal resistance of a multi-cell unit battery composed of a plurality of secondary batteries. An internal resistance measuring device and a measuring method are provided.

  In order to solve the above-mentioned problems, the present invention is a secondary battery internal resistance measuring device, wherein a DC power supply device, a constant current control circuit connected in series to the DC power supply device, and a secondary battery are connected to each other. Two or more possible switches, wherein the secondary battery is connected in series to the DC power supply device and the constant current control circuit, and the connection direction to the secondary battery can be switched individually. And two or more voltmeters that respectively measure the voltages of the secondary batteries connected to the respective switches, and the two or more switches are connected to the secondary batteries connected to the respective switches. The connection direction is switched to charge / discharge the plurality of secondary batteries, and the internal resistance of each secondary battery is measured from the current value of the constant current control circuit and the voltage value of each voltmeter.

  According to a second aspect of the present invention, in the secondary battery internal resistance measuring device according to the first aspect of the present invention, each of the switches includes two one-circuit two-contact switches that can be individually controlled.

  According to a third aspect of the present invention, in the secondary battery internal resistance measuring device according to the first or second aspect, when the two or more switches measure the internal resistance of each of the secondary batteries, at least one Switching is performed such that the connection direction of the secondary battery connected to the switch is opposite to the connection direction of the secondary battery connected to the other switch.

  According to a fourth aspect of the present invention, in the secondary battery internal resistance measuring device according to any one of the first to third aspects, the secondary batteries connected to the respective switches have the same rated voltage, and the DC power supply The apparatus is characterized in that the rated voltage is equal to or lower than the secondary battery.

  According to a fifth aspect of the present invention, in the secondary battery internal resistance measuring device according to any one of the first to fourth aspects, the plurality of secondary batteries are connected in series via the switch. And

  The invention according to claim 6 is a secondary battery internal resistance measuring method for measuring an internal resistance of the secondary battery from a current value and a voltage value when a plurality of secondary batteries are charged / discharged. Connecting the secondary batteries in series so that the connection direction of at least one of the secondary batteries is opposite to the connection direction of the other secondary batteries, and supplying a constant current to the plurality of secondary batteries A step of recording a current value of the constant current and a voltage value of the plurality of secondary batteries, a step of switching a current direction of the plurality of secondary batteries in a reverse direction, and a step of supplying the constant current Repeating the step of recording and the step of switching the current direction in the reverse direction, and measuring the internal resistance of each secondary battery from the recorded current value and the voltage value. And butterflies.

  The invention according to claim 7 is the secondary battery internal resistance measuring method according to claim 6, wherein the plurality of secondary batteries have the same rated voltage, and the constant current is a rated voltage equal to or lower than the secondary battery. It is supplied from a direct current power source.

  INDUSTRIAL APPLICABILITY The present invention has an effect of reducing the size of a secondary battery internal resistance measuring device that measures the internal resistance of a multi-cell unit type battery including a plurality of secondary batteries, facilitating movement of the device, and saving power.

It is a figure which shows the structure of the secondary battery internal resistance measuring apparatus which concerns on one Embodiment of this invention. (A), (b) is a figure which shows the operation condition of the secondary battery internal resistance measuring apparatus which concerns on one Embodiment of this invention. (A), (b) is a figure which shows FIG. 2 (a), (b) roughly. (A) is a figure which shows the charge transfer from the secondary battery 4-1 to the secondary battery 4-2, (b) is the charge transfer from the secondary battery 4-2 to the secondary battery 4-1. FIG. It is a figure which shows the case where two secondary batteries with the same amount of stored charges are connected in parallel. It is a figure which shows a mode that the voltage rise of the battery (DC power supply) of a discharge side is compensated with the DC power supply 1 installed separately. (A), (b) is the connection state of the switch in the case of measuring the internal resistance of the secondary battery in the secondary battery internal resistance measuring device according to one embodiment of the present invention by the same measurement method as the prior art. FIG. It is a figure which shows the test order regarding the internal resistance measurement of the secondary battery which IEC62660-1 standard defines. (A) is a figure which shows the structure of the secondary battery internal resistance measuring apparatus of a prior art, (b) is the schematic. (A) is a figure which shows the discharge state of the secondary battery internal resistance measuring apparatus of a prior art, (b) is the schematic. It is a figure which shows the discharge current seen from the secondary battery, and the direction of a charging current. It is a figure which shows the structure of the internal resistance measuring apparatus of the multi-cell unit type battery in a prior art.

Hereinafter, embodiments of the present invention will be described in detail.
In FIG. 1, the structure of the secondary battery internal resistance measuring apparatus which concerns on one Embodiment of this invention is shown. One terminal of the constant current control circuit 2 is connected to the positive electrode of the DC power supply 1, and the other terminal of the constant current control circuit 2 is connected to the contact c of the switch 3-1a of the switch 3-1. 1 is connected to the contact c of the switch 3-2b of the switch 3-2. The contact c of the switch 3-1b of the switch 3-1 and the contact c of the switch 3-2a of the switch 3-2 are connected, and the switches 3-1 and 3-2 are connected in series.

  The secondary battery 4-1 can be connected to the contacts a and b of the switches 3-1a and 3-1b of the switching device 3-1, and the contact c is switched to the secondary battery by switching the switches 3-1a and 3-1b. It is possible to switch the connection between the 4-1 positive electrode and the negative electrode. Similarly, the secondary battery 4-2 can be connected to the switch 3-2. In addition, voltmeters 5-1 and 5-2 are installed so that the voltages of the secondary batteries 4-1 and 4-2 can be measured.

  Although FIG. 1 shows a case where there are two switching devices and two voltmeters, one voltmeter is installed for each secondary battery unit to be measured. Moreover, you may provide the arbitrary number of two or more switches.

  2 (a) and 2 (b) show the operating conditions when measuring the internal resistance at a low voltage of the secondary battery internal resistance measuring device according to one embodiment of the present invention.

  FIG. 2A shows that the secondary battery 4-1 is in a discharged state and the secondary battery 4-2 is in a charged state. In this way, the contacts c of the switches 3-1a and 3-1b of the switch 3-1 are connected to the contacts b, and the contacts c of the switches 3-2a and 3-2b of the switch 3-2 are connected to the contacts a. When connected, the secondary battery 4-1 is discharged, and the secondary battery 4-2 is charged.

  FIG. 2B shows that the secondary battery 4-2 is in a discharged state and the secondary battery 4-1 is in a charged state. In this way, the switching devices 3-1 and 3-2 are switched to connect the contact c of the switches 3-1 a and 3-1 b of the switching device 3-1 to the contact a, and the switch 3 of the switching device 3-2. When the contact c of -2a and 3-2b is connected to the contact b, the secondary battery 4-2 is discharged and the secondary battery 4-1 is charged.

  As described above, in the embodiment of the present invention, when measuring the internal resistance of the secondary battery at a low voltage, each switch always reverses the connection direction of the connected secondary battery by the two switches. It is controlled to become. That is, in the present invention, two or more switchers are provided, and by controlling these two or more switchers, the connection direction of at least one secondary battery is reversed with respect to the connection direction of other secondary batteries. To do.

  3 (a) and 3 (b) schematically show FIGS. 2 (a) and 2 (b). In FIG. 3A, the secondary battery 4-1 functions as a DC power source for charging the secondary battery 4-2, and the discharge current i1 from the secondary battery 4-1 is the secondary battery 4-2. Is used as a charging current i1. In FIG. 3 (b), the batteries 4-1 and 4-2 are connected in the reverse direction with respect to FIG. 3 (a), and the secondary battery 4-2 serves as a DC power source for charging the secondary battery 4-1. The discharging current i1 from the secondary battery 4-2 is used as the charging current i1 to the secondary battery 4-1.

  The main object of the present invention is to reduce the size and power consumption of an internal resistance measuring device of a high-voltage multi-cell unit type secondary battery mounted on an EV vehicle. The internal resistance of the secondary battery can also be measured.

  In the present invention, if two secondary batteries are paired and configured to have the orientation of FIG. 3A and the orientation of FIG. 3B, even if the internal resistance of the secondary battery is measured, Ideally, only the charge needs to move between the secondary batteries 4-1 and 4-2, that is, no DC power supply device other than the secondary batteries 4-1 and 4-2 is required. Therefore, by utilizing such characteristics of the secondary battery, the power capacity of the DC power supply device 1 can be made smaller than that of the prior art, and the test order determined by IEC62660-1 at a low voltage can be executed. It is possible to reduce the size and power consumption of the secondary battery internal resistance measuring device that can also measure the resistance inside the secondary battery when mounted in a car. This will be described in more detail below.

  FIG. 4A is a diagram illustrating charge transfer from the secondary battery 4-1 to the secondary battery 4-2. As can be seen from the figure, the current i1 is a discharge current from the secondary battery 4-1 (DC power supply), and is also a charging current to the secondary battery 4-2.

  Since the charge Q can be expressed by the following equation, the amount of the current i1 corresponds to the amount of charge transferred from the secondary battery 4-1 (DC power supply) to the secondary battery 4-2, and the secondary The amount of charge released from the battery 4-1 (DC power supply) is equal to the amount of charge transferred to the secondary battery 4-2.

FIG. 4B is a diagram illustrating charge transfer from the secondary battery 4-2 to the secondary battery 4-1.
The current i2 is a discharge current from the secondary battery 4-2 (DC power supply), and is also a charging current to the secondary battery 4-1. Therefore, when the current i1 is equal to the current i2, the amount of charge released from the secondary battery 4-2 (DC power supply) is equal to the amount of charge transferred to the secondary battery 4-1.

  If this series of operations is performed at the same time, the secondary battery in the discharged state acts as a DC power source, and charges move only between the secondary batteries 4-1 and 4-2. This DC power supply device is not necessary. The test order defined by IEC62660-1 requires that the battery is first discharged at a current value of 1/3 It for 10 seconds, then rested for a certain period of time, and then charged again at a current value of 1/3 It for 10 seconds. . In the configuration of the present invention, either the secondary battery 4-1 or the secondary battery 4-2 is discharged, and at the same time, the other is charged. Therefore, the charging / discharging operation at the current value of 1/3 It is performed. Are executed simultaneously.

  For example, when the secondary battery 4-1 is in a discharged state and the secondary battery 4-2 is in a charged state, the current value is changed from the secondary battery 4-1 to the secondary battery 4-2 at the current value of 1/3 It. The switches 3-1 and 3-2 are controlled such that the secondary battery 4-2 is in a discharged state and the secondary battery 4-1 is in a charged state after a certain period of time has elapsed since the corresponding charge has moved. . The charge corresponding to the current value of 1/3 It again moves from the secondary battery 4-2 to the secondary battery 4-1.

  As described above, in the present plan, it is not necessary to provide a separate DC power supply in principle, but the charge stored in the secondary battery 4-1 and the secondary battery 4-2 by a series of charge / discharge operations. If the amounts are equal, the charge / discharge operation may be instantaneously stopped even when the test order determined by IEC62660-1 is being executed.

FIG. 5 shows a case where two secondary batteries having the same accumulated charge amount are connected in parallel. The charge Q is expressed by the following formula. Therefore, assuming that the capacitors C are equal, the voltage values when the amounts of accumulated charges are equal are approximately equal.
Q = C × V

  However, since the voltage rising curve at the time of charging the secondary battery and the voltage falling curve at the time of discharging are both non-linear, the voltage when the accumulated charge amount of both is not necessarily the same. In order to solve such a problem, in the present invention, a DC power supply 1 having an upper limit of the voltage value at the time of full charge, that is, the rated voltage of the secondary battery is separately provided.

  FIG. 6 shows how the voltage increase of the battery (DC power supply) on the discharge side is compensated by the separately installed DC power supply 1. The voltage value (test voltage value) of the DC power supply of the prior art depends on the number of single-cell secondary batteries connected in series and in parallel, and the test voltage increases as the number increases. Therefore, for example, when four secondary batteries having a single cell rated voltage of 50 volts are connected in series, a test voltage of 200 volts is required and the test current also depends on the rated current of the single cell. The more you increase, the more power you need.

  On the other hand, in the case of the present invention, two secondary batteries are made into one set, and one secondary battery on the discharge side acts as a DC power source for the other secondary battery for charging, and the combined two secondary batteries In order to carry out the test order defined by IEC62660-1 by alternately discharging and charging between batteries, the charge transfer by the internal resistance measurement is performed only between the secondary batteries 4-1 and 4-2. A DC power supply device having a much smaller capacity than that of the prior art may be provided separately.

  Further, the test voltage value of the DC power supply device may be 50 volts at the maximum when the rated voltage of the single cell is 50 volts, for example. That is, the DC power source 1 of the present invention works as an auxiliary power source for the secondary battery on the discharge side, unlike the DC power source 21 of the prior art.

  As described above, according to the present invention, it is possible to measure the internal resistance of a high-voltage multi-cell unit type secondary battery mounted on an EV car, and the power consumption is small, light weight, small size, and portability. An excellent secondary battery internal resistance measuring device can be realized.

  In the secondary battery internal resistance measuring device of the present invention, when the internal resistance of the secondary battery is not measured, charging / discharging at a high voltage is performed by controlling the switch so as to unify the connection direction of the secondary battery. It is also possible to measure the internal resistance of the secondary battery by the same measurement method as in the prior art.

  FIG. 7 shows a connection state of the switch when the internal resistance of the secondary battery is measured by the same measurement method as that of the conventional technique in the secondary battery internal resistance measurement apparatus according to the embodiment of the present invention. In this case, the secondary batteries 4-1 and 4-2 can be both discharged by connecting the contacts c of the switching devices 3-1, 3-2 to the contact b. Further, by connecting both the contacts c of the switching devices 3-1 and 3-2 to the contact a, both the secondary batteries 4-1 and 4-2 can be charged.

  As described above, in the present plan, the switching operation of the switching device 3-1 and the switching device 3-2 can be controlled to easily switch to the measurement of the internal resistance of the secondary battery in the prior art.

1, 2 1 DC power supply device 2, 22 Constant current control circuit 3-1, 3-2, 23 switch 3-1a, 3-1b, 3-2a, 3-2b, 23a, 23b, switch 4-1, 4 -2, 24, 24a, 24b Secondary battery 5-1, 5-2, 25, 25a, 25b Voltmeter

Claims (7)

A DC power supply,
A constant current control circuit connected in series to the DC power supply device;
Two or more switchers each capable of connecting a secondary battery, wherein the secondary battery is connected in series to the DC power supply device and the constant current control circuit, and the connection direction to the secondary battery can be individually switched Two or more switchers,
Two or more voltmeters each measuring the voltage of the secondary battery connected to each switch;
And the two or more switches switch the connection direction to the secondary battery connected to each switch to charge / discharge the plurality of secondary batteries, and the current value of the constant current control circuit and A secondary battery internal resistance measuring device that measures the internal resistance of each secondary battery from the voltage value of each voltmeter.   The secondary battery internal resistance measuring device according to claim 1, wherein each switching unit includes two one-circuit two-contact switches that can be individually controlled.   When the two or more switching devices measure the internal resistance of each of the secondary batteries, the connection direction of the secondary battery connected to at least one of the switching devices is the secondary connected to the other switching device. The secondary battery internal resistance measuring device according to claim 1 or 2, wherein switching is performed so as to be reversed with respect to a connection direction of the battery.   4. The secondary battery connected to each of the switchers has the same rated voltage, and the DC power supply device has a rated voltage equal to or lower than the secondary battery. 5. Secondary battery internal resistance measurement device.   The secondary battery internal resistance measuring apparatus according to claim 1, wherein the plurality of secondary batteries are connected in series via the switch. A secondary battery internal resistance measurement method for measuring the internal resistance of the secondary battery from a current value and a voltage value when charging and discharging a plurality of secondary batteries,
Connecting the plurality of secondary batteries in series, and connecting the connection direction of at least one of the secondary batteries to be opposite to the connection direction of the other secondary batteries;
Supplying a constant current to the plurality of secondary batteries;
Recording a current value of the constant current and a voltage value of the plurality of secondary batteries;
Switching the current direction of the plurality of secondary batteries to a reverse direction;
Supplying the constant current, repeating the recording step, and switching the current direction in the reverse direction, and measuring the internal resistance of each secondary battery from the recorded current value and the voltage value; ,
A method for measuring the internal resistance of a secondary battery, comprising:   The secondary battery internal resistance measurement according to claim 6, wherein the plurality of secondary batteries have the same rated voltage, and the constant current is supplied from a DC power source having a rated voltage equal to or lower than the secondary battery. Method.

Images