Battery pack

Abstract

The present invention provides a battery pack capable of easily diagnosing the internal resistance deterioration degree of a battery by itself. A battery pack (40) is provided with: a battery (50); contactors (75, 76); an AC constant current source (3) that supplies an AC constant current of a predetermined frequency to the battery (50); an AC voltmeter (4) that detects a voltage value between the positive electrode (51) and the negative electrode (52) when an AC constant current is supplied to the battery (50); and a control unit (85) that, by controlling the AC constant current source (3) to supply the AC constant current to the battery (50), calculates the internal resistance of the battery (50) on the basis of the voltage value detected by the AC voltmeter (4), and diagnoses the degree of deterioration of the battery (50) on the basis of the internal resistance.

Description

Technical Field

[0001] The present invention relates to a battery pack installed in a hybrid system. Background Art

[0002] With the requirements for low pollution and conservation of fossil fuel resources, hybrid systems that use an engine, an electric motor, and a battery simultaneously are being developed for industrial machinery, automobiles, etc. A hybrid system, for example, includes: an internal combustion engine that generates power using fossil fuel; an electric motor that assists the internal combustion engine; and a battery such as a lithium ion battery that supplies power to the electric motor.

[0003] In a hybrid system, a battery pack including, for example, lithium ion batteries is used as a power source for driving an electric motor. In a lithium ion battery, due to long-term storage or long-term use, internal resistance degradation occurs in which the internal resistance gradually increases and the voltage drop amount during discharge gradually increases. When internal resistance degradation occurs, an ECU (Electronic Control Unit) sometimes performs output limitation in order to suppress the voltage range.

[0004] Patent Document 1 discloses a method for detecting degradation of a lithium secondary battery and a degradation detector that detect at least any one of a set of a charging termination voltage during closed circuit and an open circuit voltage after charging, and a set of a discharging termination voltage during closed circuit and an open circuit voltage after discharging of the lithium secondary battery, calculates a determination value based on the detected set of voltages, and estimates the degree of degradation of the lithium secondary battery based on a result of comparing the determination value with a reference value stored in advance. However, in the degradation detection method and degradation detector described in Patent Document 1, it is necessary to detect at least any one of a set of a charging termination voltage during closed circuit and an open circuit voltage after charging, and a set of a discharging termination voltage during closed circuit and an open circuit voltage after discharging, and a discharging resistor or the like that can perform charging or discharging is required. Therefore, it is difficult to simply diagnose the degree of internal resistance degradation of the battery by the battery pack itself without providing a discharging resistor such as a DC / DC converter.

[0005] Patent Document 2 discloses a method for determining degradation of a storage battery that measures the internal impedance of the storage battery under test during discharge, and determines degradation of the storage battery under test based on the maximum value during a sharp rise in the internal impedance before approaching the discharging termination voltage being greater than the maximum value of the internal impedance of a non-defective storage battery. However, similar to Patent Document 1, in the method for determining degradation of the storage battery described in Patent Document 2, a load such as a discharging resistor is required. Therefore, it is difficult to simply diagnose the degree of internal resistance degradation of the battery by the battery pack itself.

[0006] A method for terminating the capacity alarm of a secondary battery is disclosed in Patent Document 3, which includes a secondary battery; a circuit for measuring the internal impedance of the secondary battery using an AC voltage with a specified period; and an alarm circuit for issuing an alarm when the internal impedance value measured by the circuit is equal to or greater than a specified value. However, the secondary battery described in Patent Document 3 is not a battery (i.e., a battery pack of lithium-ion batteries) installed in the battery pack of a hybrid system. The battery pack installed in a hybrid system includes various electrical devices such as contactors. Therefore, there is room for improvement in applying the degradation diagnosis based on the measurement of the internal impedance of the secondary battery to the battery pack of lithium-ion batteries.

[0007] In summary, for the battery pack installed in a hybrid system, it is desirable to be able to simply diagnose the degree of internal resistance degradation of the battery through the battery pack itself.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2008-192607

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 09-134742

[0012] Patent Document 3: Japanese Patent Application Laid-Open No. 63-157080 Summary of the Invention

[0013] Problems to be Solved by the Invention

[0014] The present invention has been completed in view of the above circumstances, and its object is to provide a battery pack that can simply diagnose the degree of internal resistance degradation of the battery through the battery pack itself.

[0015] Technical Solution for Solving the Problems

[0016] A first aspect of the present invention is a battery pack installed in a hybrid system, characterized by including: a battery that supplies power to an electric generator of the hybrid system; a contactor that is provided in at least one of a first wiring between the positive electrode of the battery and the electric generator and a second wiring between the negative electrode of the battery and the electric generator, and conducts or interrupts at least one of the first wiring and the second wiring; an AC constant current source that provides an AC constant current with a specified frequency to the battery; an AC voltmeter that detects the voltage value between the positive electrode and the negative electrode when the AC constant current is provided to the battery; and a control unit that provides the AC constant current to the battery by controlling the AC constant current source, calculates the internal resistance of the battery based on the voltage value detected by the AC voltmeter, and diagnoses the degree of degradation of the battery based on the internal resistance.

[0017] A second aspect of the present invention is a battery pack installed in a hybrid system, characterized by comprising: a housing; a battery disposed inside the housing for supplying power to an electric generator of the hybrid system; a contactor disposed in at least one of a first wiring between the positive electrode of the battery and the electric generator and a second wiring between the negative electrode of the battery and the electric generator, for making and breaking at least one of the first wiring and the second wiring; a third wiring connected to the first wiring; a fourth wiring connected to the second wiring; a first terminal connected to an end of the third wiring and disposed on the housing, and connected to one terminal of a measuring device for measuring the internal resistance of the battery; and a second terminal connected to an end of the fourth wiring and disposed on the housing, and connected to the other terminal of the measuring device.

[0018] Advantages of the Invention

[0019] According to the present invention, it is possible to provide a battery pack that can simply diagnose the degree of deterioration of the internal resistance of a battery by itself. Description of the Drawings

[0020] Figure 1 is a block diagram showing a hybrid system equipped with the battery pack of the first embodiment of the present invention.

[0021] Figure 2 is a graph showing an example of the behavior of voltage variation of a battery when current flows from the battery to an electric generator.

[0022] Figure 3 is a graph showing the relationship between the degree of deterioration and the amount of voltage change during charge and discharge and the output.

[0023] Figure 4 is a block diagram showing a hybrid system equipped with the battery pack of the second embodiment of the present invention.

[0024] Figure 5 is a flowchart showing the diagnostic process of the degree of deterioration of the battery of the present embodiment.

[0025] Figure 6 is a block diagram showing a hybrid system equipped with the battery pack of the third embodiment of the present invention. Detailed Embodiments

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0027] It should be noted that the following described embodiments are preferred specific examples of the present invention, and thus various technically preferred limitations are given. However, the scope of the present invention is not limited to these embodiments as long as there is no description in the following that particularly limits the meaning of the present invention. In addition, in each drawing, the same reference numerals are assigned to the same components, and detailed descriptions are appropriately omitted.

[0028] Figure 1 It is a block diagram showing a hybrid system equipped with the battery pack of the first embodiment of the present invention.

[0029] Figure 1 The hybrid system 10 shown includes an engine 1, a motor generator 2, and a battery pack 40.

[0030] The engine 1 is, for example, a supercharged high-output multi-cylinder diesel engine such as a three-cylinder engine or a four-cylinder engine with a turbocharger. However, the engine 1 is not limited to a diesel engine. The engine 1 has an ECU (Electronic Control Unit) 150. The ECU 150 controls the operation of the engine 1 and communicates with the motor generator 2 through, for example, CAN (Controller Area Network) to control the motor generator 2.

[0031] The motor generator 2 operates by the power supplied from the battery pack 40 to assist the engine 1 when power is required, such as when starting or accelerating an industrial machine equipped with the hybrid system 10. It should be noted that the hybrid system 10 is installed on industrial machines such as construction machines including forklifts and agricultural machines including tractors. In addition, the motor generator 2 converts the kinetic energy of an industrial machine equipped with the hybrid system 10 into electrical energy for power generation using regenerative braking, etc. The motor generator 2 has an inverter built-in. However, the inverter does not necessarily have to be built into the motor generator 2 and may be provided separately from the motor generator 2.

[0032] The battery pack 40 has a battery 50 and a BMU (Battery Management Unit) 85. The BMU 85 of the present embodiment is an example of the "control unit" of the present invention. The battery 50 is provided as a drive power source for the motor generator 2 and supplies power to the motor generator 2. The battery 50 has a positive terminal 51 and a negative terminal 52. The positive terminal 51 of the present embodiment is an example of the "positive electrode" of the present invention. The negative terminal 52 of the present embodiment is an example of the "negative electrode" of the present invention. As the battery 50, for example, a 48V high-voltage type lithium-ion battery (LiB) etc. can be cited. However, the battery 50 is not limited to a lithium-ion battery. In addition, the voltage of the battery 50 is not limited to 48V and may be 48V or more.

[0033] The electric generator 2 is connected to the positive electrode wiring 174 connected to the positive terminal 51 of the battery 50. The positive electrode wiring 174 is the wiring that electrically connects the positive terminal 51 of the battery 50 and the electric generator 2. The positive electrode wiring 174 is an example of the "first wiring" of the present invention. In addition, the electric generator 2 is connected to the negative electrode wiring 175 connected to the negative terminal 52 of the battery 50. The negative electrode wiring 175 is the wiring that electrically connects the negative terminal 52 of the battery 50 and the electric generator 2. The negative electrode wiring 175 is an example of the "second wiring" of the present invention.

[0034] The battery pack 40 also includes a positive side contactor 75, a negative side contactor 76, and a current value detection unit 65. It should be noted that the battery pack 40 does not necessarily have to have both the positive side contactor 75 and the negative side contactor 76, and may have only the positive side contactor 75, or may have only the negative side contactor 76. In the following description, the case where the battery pack 40 has both the positive side contactor 75 and the negative side contactor 76 is taken as an example for description.

[0035] The positive side contactor 75 is an example of the "first contactor" of the present invention, and is provided on the circuit between the positive terminal 51 of the battery 50 and the electric generator 2, that is, on the positive electrode wiring 174. The positive side contactor 75 is electrically connected to the ECU 150 through the signal line 181, and turns on and off the positive electrode wiring 174 based on the control signal sent from the ECU 150 through the signal line 181.

[0036] It should be noted that the positive side contactor 75 may also be electrically connected to the BMU 85. In this case, the positive side contactor 75 turns on and off the positive electrode wiring 174 based on the control signal sent from the BMU 85.

[0037] The negative side contactor 76 is an example of the "second contactor" of the present invention, and is provided on the circuit between the negative terminal 52 of the battery 50 and the electric generator 2, that is, on the negative electrode wiring 175. The negative side contactor 76 is electrically connected to the BMU 85 through the signal line 182, and turns on and off the negative electrode wiring 175 based on the control signal sent from the BMU 85 through the signal line 182.

[0038] It should be noted that the negative side contactor 76 may also be electrically connected to the ECU 150. In this case, the negative side contactor 76 turns on and off the negative electrode wiring 175 based on the control signal sent from the ECU 150.

[0039] The BMU85 is electrically connected to the battery 50 via the signal line 183, and detects the voltage value of the battery 50 based on the signal transmitted from the battery 50 via the signal line 183. Specifically, the BMU85 uses an internal circuit built into the BMU85 itself to detect the voltage values of the individual battery cells built into the battery 50, and detects the sum of the voltage values of the individual battery cells as the voltage value of the battery 50. The BMU85 monitors the state of the battery 50, and is able to detect an abnormality of the battery 50 based on the signal transmitted from the battery 50 via the signal line 183. For example, the BMU85 detects the voltage value of the battery 50 based on the signal transmitted from the battery 50 via the signal line 183, and detects overcharge abnormality and overdischarge abnormality.

[0040] The BMU85 is electrically connected to the current value detection unit 65 via the signal line 184, and obtains the current value from the current value detection unit 65 via the signal line 184. The current value detection unit 65 is provided on the positive electrode wiring 174, and detects the current value flowing through the positive electrode wiring 174. That is, the BMU85 obtains the current value flowing through the positive electrode wiring 174 from the current value detection unit 65 via the signal line 184. The BMU85 detects overcurrent abnormality based on the current value obtained from the current value detection unit 65 via the signal line 184. Alternatively, the BMU85 detects over-temperature abnormality based on the battery cell temperature obtained from a CMU (Cell Management Unit; not shown).

[0041] In addition, the BMU85 is electrically connected to the ECU150 via the signal line 193, and controls the negative side contactor 76 based on the control signal transmitted from the ECU150 via the signal line 193. The ECU150 and the BMU85 communicate with each other via CAN and monitor each other's states, for example.

[0042] Here, in a secondary battery such as a lithium-ion battery, due to long-term storage or long-term use, internal resistance deterioration occurs in which the internal resistance gradually increases and the voltage drop amount during discharge gradually increases. This will be described below with reference to the drawings.

[0043] Figure 2 It is a graph showing an example of the behavior of voltage variation of the battery when current flows from the battery to the motor generator.

[0044] Figure 3 It is a graph showing the relationship between the degree of deterioration and the amount of voltage change during charge and discharge and the output.

[0045] As Figure 2As shown, when current flows from the battery 50 to the motor generator 2 and passes through a specified time, the voltage value of the battery 50 detected by the BMU 85 decreases. That is, when the battery 50 discharges, a voltage drop occurs in the battery 50. Then, for example, when a metal compound adheres to the negative electrode of the battery 50, causing an increase in the internal resistance of the battery 50 and deterioration of the internal resistance of the battery 50, as Figure 2 shown by the arrow, the amount of voltage drop during discharge increases.

[0046] Then, as Figure 3 shown, when deterioration of the internal resistance of the battery 50 occurs and the amount of voltage change during charge and discharge (i.e., the amount of voltage drop during discharge in the Figure 2 description) becomes above the threshold value, the ECU 150 sometimes performs output limitation to suppress the voltage range.

[0047] Here, as a general method for detecting deterioration of secondary batteries such as lithium-ion batteries, for example, a method using a DC / DC converter and a load such as a discharge resistor can be cited. However, in such a deterioration detection method, since a discharge resistor is required, it is difficult to simply diagnose the degree of internal resistance deterioration of the battery by the battery pack itself. In addition, the battery 50 of the battery pack 40 mounted on the hybrid system 10 is set as a battery pack formed by connecting a plurality of battery cells in series in order to obtain a required voltage (48V in the above example). Therefore, as described above, the battery pack 40 not only has the battery 50, but also various electrical devices such as the positive-side contactor 75, the negative-side contactor 76, and the current value detection unit 65. Therefore, depending on the deterioration detection method, at least one resistance element among the positive-side contactor 75, the negative-side contactor 76, and the current value detection unit 65 may be added, and it is difficult to simply diagnose the degree of internal resistance deterioration of the battery by the battery pack itself.

[0048] In contrast, as Figure 1 shown, the battery pack 40 of the present embodiment further includes an AC constant current source 3 and an AC voltmeter 4. The AC constant current source 3 is connected to the positive wiring 174 via the first lead 31 at the connection point 33 between the positive terminal 51 of the battery 50 and the positive-side contactor 75. The connection point 33 of the present embodiment is an example of the "second connection point" of the present invention. In the Figure 1 shown battery pack 40, the AC constant current source 3 is connected to the positive wiring 174 via the first lead 31 at the connection point 33 between the positive terminal 51 of the battery 50 and the current value detection unit 65.

[0049] In addition, the alternating current constant current source 3 is connected to the negative electrode wiring 175 at a connection point 34 between the negative electrode terminal 52 of the battery 50 and the negative electrode side contactor 76 via a second lead wire 32. The connection point 34 in the present embodiment is an example of the "fourth connection point" of the present invention.

[0050] The alternating current constant current source 3 is electrically connected to the BMU 85 via a signal line 186, and based on a signal sent from the BMU 85 via the signal line 186, an alternating current constant current with a frequency of 1 kilohertz (kHz) is supplied to the battery 50, for example, via a first lead wire 31 and a second lead wire 32. It should be noted that the frequency of the alternating current constant current supplied by the alternating current constant current source 3 to the battery 50 is not limited to 1 kHz.

[0051] The alternating current voltmeter 4 is connected to the positive electrode wiring 174 at a connection point 43 between the positive electrode terminal 51 of the battery 50 and the positive electrode side contactor 75 via a first lead wire 41. The connection point 43 in the present embodiment is an example of the "first connection point" of the present invention. In Figure 1 In the battery pack 40 shown, the alternating current voltmeter 4 is connected to the positive electrode wiring 174 at a connection point 43 between the positive electrode terminal 51 of the battery 50 and the current value detection unit 65 via a first lead wire 41.

[0052] In addition, the alternating current voltmeter 4 is connected to the negative electrode wiring 175 at a connection point 44 between the negative electrode terminal 52 of the battery 50 and the negative electrode side contactor 76 via a second lead wire 42. The connection point 44 in the present embodiment is an example of the "third connection point" of the present invention.

[0053] When the alternating current constant current source 3 supplies an alternating current constant current to the battery 50 based on a signal sent from the BMU 85, the alternating current voltmeter 4 detects the voltage value generated between the positive electrode terminal 51 and the negative electrode terminal 52 of the battery 50.

[0054] The BMU 85 is electrically connected to the alternating current voltmeter 4 via a signal line 185, and obtains the voltage value detected by the alternating current voltmeter 4 via the signal line 185. That is, the BMU 85 obtains from the alternating current voltmeter 4 via the signal line 185 the voltage value generated between the positive electrode terminal 51 and the negative electrode terminal 52 of the battery 50 when the alternating current constant current source 3 supplies an alternating current constant current to the battery 50 based on a signal sent from the BMU 85. Then, the BMU 85 calculates the internal resistance of the battery 50 based on the voltage value obtained from the alternating current voltmeter 4.

[0055] As Figure 1As shown, the connection point 43 where the AC voltmeter 4 is connected to the positive wiring 174 is located between the connection point 33 where the AC constant current source 3 is connected to the positive wiring 174 and the positive terminal 51. The connection point 44 where the AC voltmeter 4 is connected to the negative wiring 175 is located between the connection point 34 where the AC constant current source 3 is connected to the negative wiring 175 and the negative terminal 52. Additionally, since the impedance (i.e., internal resistance) of the AC voltmeter 4 is very large, when the AC constant current source 3 supplies an AC constant current to the battery 50 based on a signal sent from the BMU 85, almost no current flows through the first lead 41 and the second lead 42 connected to the AC voltmeter 4. Thus, the AC voltmeter 4 can detect the voltage value generated between the positive terminal 51 of the battery 50 and the negative terminal 52 of the battery 50 without being affected by the respective wiring resistances of the first lead 41 and the second lead 42 and the respective contact resistances of the connection point 43 and the connection point 44.

[0056] Next, a second embodiment of the present invention will be described.

[0057] It should be noted that in the case where the components of the battery pack in the second embodiment are the same as those of the battery pack in the Figures 1 to 3 described first embodiment, the repeated descriptions will be appropriately omitted. Hereinafter, the description will focus on the differences.

[0058] Figure 4 is a block diagram showing a hybrid system equipped with the battery pack of the second embodiment of the present invention.

[0059] Figure 4 The hybrid system 10A shown includes an engine 1, an electric generator 2, and a battery pack 40A.

[0060] The battery pack 40A has a battery 50 and a BMU 85A. The BMU 85A in this embodiment is an example of the "control unit" of the present invention. The BMU 85A includes an AC constant current source 3 and an AC voltmeter 4. That is, in the battery pack 40A of this embodiment, the Figures 1 to 3 described AC constant current source 3 and AC voltmeter 4 are included in the BMU 85A. In this regard, the battery pack 40A of the second embodiment is different from the battery pack 40 of the Figures 1 to 3 described first embodiment.

[0061] The AC constant current source 3 and the AC voltmeter 4 can be implemented by hardware, or by a combination of hardware and software. Alternatively, the AC constant current source 3 and the AC voltmeter 4 can also be implemented by a computer executing a program stored in a storage unit (not shown) of the BMU85A. The "computer" mentioned here is not limited to a personal computer, and also includes arithmetic processing devices, microcomputers, etc. included in information processing devices, and is a general term for devices and apparatuses capable of implementing the functions of the present invention through programs.

[0062] Based on the signal sent from the BMU85A, the AC constant current source 3 supplies an AC constant current with a frequency of, for example, 1 kilohertz (kHz) to the battery 50 through the signal line 183. It should be noted that the frequency of the AC constant current supplied by the AC constant current source 3 to the battery 50 is not limited to 1 kHz.

[0063] When the AC constant current source 3 supplies an AC constant current to the battery 50 based on the signal sent from the BMU85, the AC voltmeter 4 detects the voltage value generated between the positive terminal 51 of the battery 50 and the negative terminal 52 of the battery 50. As described regarding Figure 1 above, for example, the AC voltmeter 4 detects the voltage values of the individual battery cells built in the battery 50 based on the signal sent from the battery 50 through the signal line 183, and detects the sum of the voltage values of the individual battery cells as the voltage value of the battery 50.

[0064] The BMU85A acquires the voltage value detected by the AC voltmeter 4. Then, the BMU85A calculates the internal resistance of the battery 50 based on the voltage value acquired from the AC voltmeter 4. The other components are the same as those of the battery pack 40 in the first embodiment described regarding Figures 1 to 3 above.

[0065] Figure 5 is a flowchart showing the diagnostic process of the deterioration degree of the battery in this embodiment.

[0066] It should be noted that Figure 5 the flowchart shown shows the diagnostic process of the deterioration degree of the battery 50 in the battery pack 40 of the first embodiment and the battery pack 40A of the second embodiment. That is, the battery pack 40 of the first embodiment and the battery pack 40A of the second embodiment can respectively execute the diagnostic process related to the Figure 5 flowchart shown. In the following description, the case where the battery pack 40 of the first embodiment executes the diagnostic process of the deterioration degree of the battery 50 is taken as an example for explanation.

[0067] First, in step S1, before the battery pack 40 is installed in the hybrid system 10, the BMU 85 calculates the internal resistance of the battery 50 based on the voltage value obtained from the AC voltmeter 4. Specifically, before the battery pack 40 is installed in the hybrid system 10, the BMU 85 controls the AC constant current source 3 to supply an AC constant current to the battery 50. At this time, the AC voltmeter 4 detects the voltage value generated between the positive terminal 51 and the negative terminal 52 of the battery 50. Then, the BMU 85 calculates the internal resistance of the battery 50 based on the voltage value obtained from the AC voltmeter 4.

[0068] Next, in step S2, the BMU 85 uses the internal resistance calculated before the battery pack 40 is installed in the hybrid system 10 as a reference. Then, in step S3, after the battery pack 40 is installed in the hybrid system 10, the BMU 85 determines whether the number of charge-discharge cycles of the battery 50 has reached a specified number. The "specified number" mentioned here is, for example, 60,000 times or more. Or, the "specified number" mentioned here is, for example, 60,000 times or more and 80,000 times or less. However, the "specified number" related to the number of charge-discharge cycles of the battery 50 is not limited to this.

[0069] When the number of charge-discharge cycles of the battery 50 has not reached the specified number (step S3: No), then in step S3, the BMU 85 determines whether the number of charge-discharge cycles of the battery 50 has reached the specified number. On the other hand, when the number of charge-discharge cycles of the battery 50 has reached the specified number (step S3: Yes), in step S4, the BMU 85 controls the AC constant current source 3 to supply an AC constant current to the battery 50.

[0070] Next, in step S5, the AC voltmeter 4 detects the voltage value generated between the positive terminal 51 and the negative terminal 52 of the battery 50.

[0071] Next, in step S6, the BMU 85 calculates the internal resistance of the battery 50 based on the voltage value obtained from the AC voltmeter 4. Then, the BMU 85 diagnoses the degree of deterioration of the battery 50 based on the increase ratio of the internal resistance calculated after the battery pack 40 is installed in the hybrid system 10 (i.e., the internal resistance calculated when the number of charge-discharge cycles of the battery 50 reaches the specified number) relative to the reference internal resistance set in step S2 (i.e., the internal resistance calculated before the battery pack 40 is installed in the hybrid system 10). For example, when the increase ratio of the internal resistance calculated after the battery pack 40 is installed in the hybrid system 10 relative to the reference internal resistance reaches a specified threshold or more, the BMU 85 determines that internal resistance deterioration of the battery 50 has occurred.

[0072] As described above, according to the present embodiment, the battery pack 40 includes: an AC constant current source 3 that supplies an AC constant current with a specified frequency to the battery 50; and an AC voltmeter 4 that detects the voltage value between the positive terminal 51 and the negative terminal 52 when the AC constant current is supplied to the battery 50. Then, the BMU 85 controls the AC constant current source 3 to supply the AC constant current to the battery 50, calculates the internal resistance of the battery 50 based on the voltage value detected by the AC voltmeter 4, and diagnoses the degree of deterioration of the battery 50 based on the calculated internal resistance. Specifically, the BMU 85 diagnoses the degree of deterioration of the battery 50 based on the ratio of the increase in the internal resistance calculated after the battery pack 40 is installed in the hybrid system 10 to the reference internal resistance calculated before the battery pack 40 is installed in the hybrid system 10. Thus, the battery pack 40 of the present embodiment does not require, for example, a DC / DC converter and a discharge resistor such as a load, and can simply diagnose the degree of deterioration of the internal resistance of the battery 50 by the battery pack 40 itself. Such an effect is also obtained in the battery pack 40A of the second embodiment.

[0073] In addition, in the battery pack 40 of the first embodiment, the AC voltmeter 4 is connected to the positive wiring 174 via the first lead 41 at the connection point 43 between the positive terminal 51 of the battery 50 and the positive-side contactor 75 ( Figure 1 the current value detection unit 65 in the battery pack 40 shown). In addition, the AC voltmeter 4 is connected to the negative wiring 175 via the second lead 42 at the connection point 44 between the negative terminal 52 of the battery 50 and the negative-side contactor 76. Thus, the battery pack 40 suppresses the resistance elements included in the positive-side contactor 75, the negative-side contactor 76, and the current value detection unit 65, that is, suppresses the influence of the resistance elements of the positive-side contactor 75, the negative-side contactor 76, and the current value detection unit 65, and can simply diagnose the degree of deterioration of the internal resistance of the battery 50 by the battery pack 40 itself.

[0074] Next, a third embodiment of the present invention will be described.

[0075] It should be noted that when the components of the battery pack in the third embodiment are the same as those of the battery pack in the Figures 1 to 3 first embodiment described above, the repeated description will be appropriately omitted, and hereinafter, the description will be centered on the differences.

[0076] Figure 6 is a block diagram showing a hybrid system equipped with the battery pack of the third embodiment of the present invention.

[0077] Figure 6 The hybrid system 10B shown includes an engine 1, an electric generator 2, and a battery pack 40B.

[0078] Compared with Figure 1 the battery pack 40 described above, the battery pack 40B of the present embodiment does not have the AC constant current source 3 and the AC voltmeter 4. On the other hand, it further has a third wiring 176, a fourth wiring 177, a first terminal 53, and a second terminal 54. In this regard, the battery pack 40B of the third embodiment is different from the battery pack 40 of the Figures 1 to 3 first embodiment described above.

[0079] One end of the third wiring 176 is connected to the positive electrode wiring 174. Specifically, one end of the third wiring 176 is connected to the positive electrode wiring 174 located between the positive electrode terminal 51 of the battery 50 and the positive electrode side contactor 75. In the Figure 6 battery pack 40B shown, one end of the third wiring 176 is connected to the positive electrode wiring 174 located between the positive electrode terminal 51 of the battery 50 and the current value detection unit 65.

[0080] In addition, the other end of the third wiring 176 is connected to the first terminal 53. The first terminal 53 is provided on the housing 401 of the battery pack 40B. For example, as shown in Figure 6 , the first terminal 53 is attached to the outer surface 411 of the housing 401 and protrudes outward from the outer surface 411 of the housing 401. The first terminal 53 is connected to one terminal of a measuring device (not shown) for measuring the internal resistance of the battery 50. As a measuring device for measuring the internal resistance of the battery 50, for example, a battery tester or the like can be cited.

[0081] One end of the fourth wiring 177 is connected to the negative electrode wiring 175. Specifically, one end of the fourth wiring 177 is connected to the negative electrode wiring 175 located between the negative electrode terminal 52 of the battery 50 and the negative electrode side contactor 76. In addition, the other end of the fourth wiring 177 is connected to the second terminal 54. The second terminal 54 is provided on the housing 401 of the battery pack 40B. For example, as shown in Figure 6 , the second terminal 54 is attached to the outer surface 411 of the housing 401 and protrudes outward from the outer surface 411 of the housing 401. The second terminal 54 is connected to the other terminal of the measuring device for measuring the internal resistance of the battery 50. As described above, as a measuring device for measuring the internal resistance of the battery 50, for example, a battery tester or the like can be cited.

[0082] For example, a battery tester (not shown) is connected to the first terminal 53 at one terminal and to the second terminal 54 at the other terminal, provides an AC constant current with a frequency of 1 kHz to the battery 50 through the third wiring 176 and the fourth wiring 177, and calculates the internal resistance of the battery 50 based on the voltage value of the AC voltmeter included in the battery tester.

[0083] As Figure 6As shown, the battery pack 40B further includes a fuse 95. The fuse 95 is provided on the third wiring 176 and disconnects the third wiring 176 when an overcurrent flows through the third wiring 176. Thus, even if it is assumed that the third wiring 176 and the fourth wiring 177 are in contact with each other and an overcurrent flows through the circuit formed by the battery 50, the third wiring 176, and the fourth wiring 177, the fuse 95 can protect the circuit of the battery pack 40B by disconnecting the third wiring 176.

[0084] The fuse 95 may also be provided on the fourth wiring 177 instead of the third wiring 176. Alternatively, the fuse 95 may be provided on both the third wiring 176 and the fourth wiring 177. Even in this case, the fuse 95 can protect the circuit of the battery pack 40B by disconnecting at least one of the third wiring 176 and the fourth wiring 177. The other configurations are the same as the components of the battery pack 40 of the Figures 1 to 3 first embodiment described above.

[0085] As described above, according to the battery pack 40B of the present embodiment, the first terminal 53 is connected to one terminal of a measuring device that measures the internal resistance of the battery 50. In addition, the second terminal 54 is connected to the other terminal of the measuring device that measures the internal resistance of the battery 50. Then, a measuring device such as a battery tester is connected to the first terminal 53 and the second terminal 54, and an alternating constant current with a frequency of 1 kHz is supplied to the battery 50 through, for example, the third wiring 176 and the fourth wiring 177. Thus, the internal resistance of the battery 50 can be calculated based on the voltage value of the alternating voltage meter. Thus, the battery pack 40B of the present embodiment does not require, for example, a discharge resistor such as a DC / DC converter and a load, and can easily diagnose the degree of deterioration of the internal resistance of the battery 50 by the battery pack 40B itself.

[0086] In addition, one end of the third wiring 176 is connected to the positive wiring 174 located between the positive terminal 51 of the battery 50 and the positive-side contactor 75 (the current value detection unit 65 in the Figure 6 battery pack 40B shown). One end of the fourth wiring 177 is connected to the negative wiring 175 located between the negative terminal 52 of the battery 50 and the negative-side contactor 76. Therefore, the resistance elements of the positive-side contactor 75, the negative-side contactor 76, and the current value detection unit 65 can be suppressed, that is, the influence of the resistance elements of the positive-side contactor 75, the negative-side contactor 76, and the current value detection unit 65 can be suppressed, and the degree of deterioration of the internal resistance of the battery 50 can be easily diagnosed by the battery pack 40B itself.

[0087] Since the battery pack 40B of the present embodiment has the first terminal 53 and the second terminal 54 which are service ports capable of always detecting high voltage, it is possible to simply diagnose the degree of internal resistance deterioration of the battery 50 by the battery pack 40B itself not only during the production process of the battery pack 40B, but also after the battery pack 40B is installed in the hybrid system 10B and supplied to the market.

[0088] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the claims. A part of the structure of the above embodiments can be omitted, or they can be arbitrarily combined in a different manner from the above.

[0089] Explanation of the drawing text

[0090] 1: Engine; 2: Motor generator; 3: AC constant current source; 4: AC voltmeter; 10: Hybrid system; 10A: Hybrid system; 10B: Hybrid system; 31: First lead wire; 32: Second lead wire; 33: Connection point; 34: Connection point; 40: Battery pack; 40A: Battery pack; 40B: Battery pack; 41: First lead wire; 42: Second lead wire; 43: Connection point; 44: Connection point; 50: Battery; 51: Positive terminal; 52: Negative terminal; 53: First terminal; 54: Second terminal; 65: Current value detection unit; 75: Positive side contactor; 76: Negative side contactor; 85: BMU; 85A: BMU; 95: Fuse; 150: ECU; 174: Positive wiring; 175: Negative wiring; 176: Third wiring; 177: Fourth wiring; 181: Signal wire; 182: Signal wire; 183: Signal wire; 184: Signal wire; 185: Signal wire; 186: Signal wire; 193: Signal wire; 401: Housing; 411: Outer surface.

Claims

1. A battery pack installed in a hybrid power system, characterized in that: have: a battery that supplies electric power to the electric motor generator of the hybrid system; a contactor provided in at least one of a first wiring between the positive electrode of the battery and the motor generator and a second wiring between the negative electrode of the battery and the motor generator, and performing switching on and off of at least one of the first wiring and the second wiring; an alternating current constant current source, providing an alternating current constant current of a specified frequency to the battery; an AC voltmeter for detecting a voltage value between the positive electrode and the negative electrode when the AC constant current is supplied to the battery; as well as The control unit supplies the AC constant current to the battery by controlling the AC constant current source, calculates the internal resistance of the battery based on the voltage value detected by the AC voltmeter, and diagnoses the degree of deterioration of the battery based on the internal resistance.

2. The battery pack according to claim 1, characterized in that: The AC constant current source and the AC voltmeter are connected to the first wiring and the second wiring, respectively.

3. The battery pack according to claim 2, characterized in that: The contactor comprises: a first contactor, provided on the first wiring, for switching the first wiring on and off; and A second contactor is provided on the second wiring to switch the second wiring on and off. The AC constant current source and the AC voltmeter are connected to the first wiring located between the positive electrode and the first contactor and the second wiring located between the negative electrode and the second contactor, respectively.

4. The battery pack according to claim 3, characterized in that: The first connection point where the AC voltmeter is connected to the first wiring is located between the second connection point where the AC constant current source is connected to the first wiring and the positive electrode. A third connection point at which the AC voltmeter is connected to the second wiring is located between a fourth connection point at which the AC constant current source is connected to the second wiring and the negative electrode.

5. The battery pack according to claim 1, characterized in that: The AC constant current source and the AC voltmeter are included in the control section.

6. The battery pack according to claim 1, characterized in that: The control portion diagnoses the degree of degradation based on a ratio of increase of the internal resistance calculated after installation of the hybrid system relative to the reference internal resistance, using the internal resistance calculated before installation of the hybrid system as a reference.

7. The battery pack according to claim 6, characterized in that: After being installed in the hybrid system, the control unit controls the AC constant current source to supply the AC constant current to the battery and calculates the internal resistance when the number of charge and discharge cycles of the battery reaches a predetermined number.

8. The battery pack according to claim 7, characterized in that: The prescribed number of times is more than 60,000 times.

9. The battery pack according to any one of claims 1 to 8, characterized in that: The prescribed frequency is 1 kHz.

10. A battery pack installed in a hybrid power system, characterized in that: have: case; a battery disposed inside the housing and supplying electric power to the electric generator of the hybrid system; a contactor provided in at least one of a first wiring between the positive electrode of the battery and the motor generator and a second wiring between the negative electrode of the battery and the motor generator, and performing switching on and off of at least one of the first wiring and the second wiring; a third wiring connected to the first wiring; a fourth wiring connected to the second wiring; a first terminal connected to an end of the third wiring and provided on the housing, and connected to one terminal of a measuring device for measuring the internal resistance of the battery; as well as The second terminal is connected to the end of the fourth wiring and is provided in the housing, and is connected to the other terminal of the measuring device.

11. The battery pack according to claim 10, characterized in that: The contactor comprises: a first contactor, provided on the first wiring, for switching the first wiring on and off; and A second contactor is provided on the second wiring to switch the second wiring on and off. The third wiring is connected to the first wiring located between the positive electrode and the first contactor, The fourth wiring is connected to the second wiring located between the negative electrode and the second contactor.

12. The battery pack according to claim 10, characterized in that: The first terminal and the second terminal are respectively attached to the outer surface of the housing.

13. The battery pack according to claim 12, characterized in that: The first terminal and the second terminal protrude outward from the outer surface, respectively.

14. The battery pack according to any one of claims 10 to 13, characterized in that: A fuse is further provided on the third wiring and disconnects the third wiring when an overcurrent flows through the third wiring.

15. The battery pack according to any one of claims 10 to 13, characterized in that: A fuse is further provided on the fourth wiring and disconnects the fourth wiring when an overcurrent flows through the fourth wiring.

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