Battery pack

Abstract

To provide a battery pack of which degradation of the internal resistance can be easily diagnosed by a single battery.SOLUTION: A battery pack 40 includes: a housing 41; a battery 50; a contact 75 provided in at least one of a first wire 174 between a positive electrode 51 of a battery 50 and a motor generator 2 and a second wire 175 between a negative electrode 52 of the battery 50 and the motor generator 2, the contact opening or closing at least one of the first wire 174 and the second wire 175; a third wire 176 connected to the first wire 174; a fourth wire 54 connected to the second wire 175; a first terminal 53 connected to an end part of the third wire 176, provided in the housing 41, and is connected to the terminal of one side of a measuring apparatus for measuring the internal resistance of the battery 50; and a second terminal 54 connected to an end part of the fourth wire 177, provided in the housing 41, and connected to the terminal of the other side of the measuring apparatus.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a battery pack mounted on a hybrid system.

Background Art

[0002] A hybrid system that combines an engine, a motor, and a battery has been developed for industrial machines, automobiles, etc. in response to the demands for reducing environmental impact and conserving fossil fuels. The hybrid system includes, for example, an internal combustion engine that uses fossil fuel to generate power, a motor that assists the internal combustion engine, and a battery such as a lithium-ion battery that supplies power to the motor.

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

[0004] Patent Document 1 discloses a method and a detector for detecting degradation of a lithium secondary battery, which detect at least one of a set of a charging end voltage at the time of a closed circuit and a voltage at the time of an open circuit after charging, and a set of a discharging end voltage at the time of a closed circuit and a voltage at the time of an open circuit after discharging of the lithium secondary battery, calculate a determination value from the detected set of voltages, and estimate the degree of degradation of the lithium secondary battery based on the result of comparing the determination value with a reference value stored in advance. However, in the degradation detection method and the degradation detector described in Patent Document 1, it is necessary to detect at least one of a set of a charging end voltage at the time of a closed circuit and a voltage at the time of an open circuit after charging, and a set of a discharging end voltage at the time of a closed circuit and a voltage at the time of an open circuit after discharging, and a discharging resistor or the like that enables charging or discharging is required. Therefore, it is difficult to simply diagnose the degree of internal resistance degradation of the battery with a single battery pack 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, which measures the internal impedance of a test storage battery during discharging and determines the degradation of the test storage battery because the maximum value at the sharp rise of the internal impedance immediately before the discharging end voltage is larger than the maximum value of the internal impedance of a non-defective storage battery. However, in the method for determining degradation of the storage battery described in Patent Document 2, a load such as a discharging resistor is required as in Patent Document 1. Therefore, it is difficult to simply diagnose the degree of internal resistance degradation of the battery with a single battery pack.

[0006] Patent Document 3 discloses a method for warning of the end of battery capacity of a secondary battery, which includes a secondary battery, a circuit for measuring the internal impedance of the secondary battery with an AC voltage of a predetermined period, and an alarm circuit for issuing an alarm when the measured internal impedance value of the circuit is equal to or greater than a predetermined value. However, the secondary battery described in Patent Document 3 is not the battery of the battery pack mounted on the hybrid system (that is, the assembled battery of lithium-ion batteries). Since the battery pack mounted on the hybrid system includes various electrical devices such as contacts, there is room for improvement in applying the degradation diagnosis based on the measurement of the internal impedance of the secondary battery to the assembled battery of lithium-ion batteries.

[0007] From the above, for the battery pack mounted on the hybrid system, it is desired that the degree of degradation of the internal resistance of the battery can be easily diagnosed with the battery pack alone.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a battery pack that can easily diagnose the degree of degradation of the internal resistance of the battery alone.

Means for Solving the Problems

[0010] One aspect of the present invention is a battery pack mounted on a hybrid system, comprising a housing, a battery provided inside the housing for supplying power to a motor generator of the hybrid system, and 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. A contact provided in at least one of the wirings for opening and closing 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, and an end of the third wiring. A first terminal that is connected to one terminal of a measuring device that measures the internal resistance of the battery and is provided on the housing, and a second terminal that is connected to the end of the fourth wiring and is provided on the housing and is connected to the other terminal of the measuring device. A battery pack characterized by comprising.

Effects of the Invention

[0011] 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 alone.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are preferred specific examples of the present invention, and thus are technically subject to various preferable limitations. However, the scope of the present invention is not limited to these aspects unless there is a description to specifically limit the present invention in the following description. In addition, in each drawing, the same reference numerals are assigned to the same components, and detailed descriptions thereof are appropriately omitted.

[0014] FIG. 1 is a block diagram showing a hybrid system equipped with a battery pack according to an embodiment of the present invention. The hybrid system 10 shown in FIG. 1 includes an engine 1, a motor generator 2, and a battery pack 40.

[0015] The engine 1 is, for example, a multi-cylinder diesel engine such as a supercharged high-output 3-cylinder engine or 4-cylinder engine having turbocharging. However, the engine 1 is not necessarily limited to a diesel engine. The engine 1 has an ECU (Electronic Control Unit). The ECU 150 controls the operation of the engine 1 and communicates with the motor generator 2 via, for example, CAN (Controller Area Network) to control the motor generator 2.

[0016] The motor generator 2 operates by the electric power supplied from the battery pack 40 to support the engine 1 when power is required, such as at the start or acceleration of an industrial machine or the like on which the hybrid system 10 is mounted. Note that the hybrid system 10 is mounted on industrial machines including, for example, construction machines such as forklifts and agricultural machines such as tractors. Further, the motor generator 2 uses, for example, a regenerative brake to convert the kinetic energy of an industrial machine or the like on which the hybrid system 10 is mounted into electric energy for power generation. The motor generator 2 incorporates an inverter. However, the inverter does not necessarily have to be incorporated in the motor generator 2 and may be provided separately from the motor generator 2.

[0017] The battery pack 40 includes a battery 50 and a BMU (Battery Management Unit) 85. The battery 50 is provided as a driving power source for the motor generator 2 and supplies power to the motor generator 2. The battery 50 has a positive electrode terminal 51 and a negative electrode terminal 52. The positive electrode terminal 51 in this embodiment is an example of the "positive electrode" of the present invention. The negative electrode terminal 52 in this embodiment is an example of the "negative electrode" of the present invention. Examples of the battery 50 include a 48V high-voltage type lithium-ion battery (LiB). However, the battery 50 is not limited to a lithium-ion battery. Also, the voltage of the battery 50 is not limited to 48V and may be 48V or higher.

[0018] The motor generator 2 is connected to a positive electrode wiring 174 connected to the positive electrode terminal 51 of the battery 50. The positive electrode wiring 174 is a wiring that electrically connects the positive electrode terminal 51 of the battery 50 and the motor generator 2. The positive electrode wiring 174 is an example of the "first wiring" of the present invention. Also, the motor generator 2 is connected to a negative electrode wiring 175 connected to the negative electrode terminal 52 of the battery 50. The negative electrode wiring 175 is a wiring that electrically connects the negative electrode terminal 52 of the battery 50 and the motor generator 2. The negative electrode wiring 175 is an example of the "second wiring" of the present invention.

[0019] The battery pack 40 further includes a positive electrode side contact 75, a negative electrode side contact 76, and a current value detection unit 65. Note that the battery pack 40 does not necessarily have both the positive electrode side contact 75 and the negative electrode side contact 76, and may have only the positive electrode side contact 75 or may have only the negative electrode side contact 76. In the following description, the case where the battery pack 40 has both the positive electrode side contact 75 and the negative electrode side contact 76 will be taken as an example.

[0020] The positive-side contact 75 is an example of the "first contact" of the present invention and is provided in the electrical circuit between the positive terminal 51 of the battery 50 and the motor generator 2, that is, in the positive wiring 174. The positive-side contact 75 is electrically connected to the ECU 150 via the signal line 181 and opens and closes the positive wiring 174 based on the control signal transmitted from the ECU 150 through the signal line 181.

[0021] Note that the positive-side contact 75 may be electrically connected to the BMU 85. In this case, the positive-side contact 75 opens and closes the positive wiring 174 based on the control signal transmitted from the BMU 85.

[0022] The negative-side contact 76 is an example of the "second contact" of the present invention and is provided in the electrical circuit between the negative terminal 52 of the battery 50 and the motor generator 2, that is, in the negative wiring 175. The negative-side contact 76 is electrically connected to the BMU 85 via the signal line 182 and opens and closes the negative wiring 175 based on the control signal transmitted from the BMU 85 through the signal line 182.

[0023] Note that the negative-side contact 76 may be electrically connected to the ECU 150. In this case, the negative-side contact 76 opens and closes the negative wiring 175 based on the control signal transmitted from the ECU 150.

[0024] The BMU 85 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 through the signal line 183. Specifically, the BMU 85 uses an internal circuit built into the BMU 85 itself to detect the voltage value of each cell built into the battery 50 and detects the sum of the voltage values of each cell as the voltage value of the battery 50. The BMU 85 monitors the state of the battery 50 and can detect an abnormality of the battery 50 based on the signal transmitted from the battery 50 through the signal line 183. For example, the BMU 85 detects the voltage value of the battery 50 based on the signal transmitted from the battery 50 through the signal line 183 and detects overcharge abnormality and overdischarge abnormality.

[0025] The BMU85 is electrically connected to the current value detection unit 65 by the signal line 184, and acquires the current value from the current value detection unit 65 through 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 acquires the current value flowing through the positive electrode wiring 174 from the current value detection unit 65 through the signal line 184. The BMU85 detects an overcurrent abnormality based on the current value acquired from the current value detection unit 65 through the signal line 184. Alternatively, the BMU85 detects an overtemperature abnormality based on the cell temperature acquired from a CMU (Cell Management Unit; not shown).

[0026] In addition, the BMU85 is electrically connected to the ECU150 by the signal line 193, and controls the negative electrode side contactor 76 based on the control signal transmitted from the ECU150 through the signal line 193. The ECU150 and the BMU85 communicate with each other, for example, via CAN, and monitor each other's states.

[0027] Here, in a secondary battery such as a lithium-ion battery, internal resistance increases due to long-term storage or long-term use, and internal resistance deterioration occurs in which the voltage drop amount during discharge increases. This will be described below with reference to the drawings.

[0028] FIG. 2 is a graph showing an example of the behavior of voltage fluctuations of the battery when current flows from the battery toward the motor generator. FIG. 3 is a graph showing the relationship between the degree of deterioration, the amount of voltage change during charge and discharge, and the output.

[0029] As shown in FIG. 2, when current flows from the battery 50 to the motor generator 2 for a predetermined time, the voltage value of the battery 50 detected by the BMU 85 drops. That is, when the battery 50 discharges, a voltage drop occurs in the battery 50. And when, for example, a metal compound adheres to the negative electrode of the battery 50, increasing the internal resistance of the battery 50 and causing internal resistance deterioration of the battery 50, as shown by the arrow in FIG. 2, the amount of voltage drop during discharge increases.

[0030] And as shown in FIG. 3, when internal resistance deterioration of the battery 50 occurs and the amount of voltage change during charge and discharge (that is, the amount of voltage drop during discharge in the description of FIG. 2) becomes equal to or greater than the threshold value, the ECU 150 may perform output limitation to suppress the voltage range.

[0031] Here, as a general method for detecting deterioration of a secondary battery such as a lithium-ion battery, for example, a method using a discharge resistor such as a DC / DC converter and a load can be mentioned. 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 with the battery pack alone. Further, the battery 50 of the battery pack 40 mounted on the hybrid system 10 is provided as a battery module in which a plurality of cells are connected in series to obtain a required voltage (48V in the above example). Therefore, as described above, the battery pack 40 has various electrical devices such as the positive electrode side contact 75, the negative electrode side contact 76, and the current value detection unit 65 in addition to the battery 50. Therefore, depending on the deterioration detection method, the resistance component of at least one of the positive electrode side contact 75, the negative electrode side contact 76, and the current value detection unit 65 may be included, and it is difficult to simply diagnose the degree of internal resistance deterioration of the battery with the battery pack alone.

[0032] On the other hand, as shown in FIG. 1, the battery pack 40 according to this embodiment further includes a third wiring 176, a fourth wiring 177, a first terminal 53, and a second terminal 54. The third wiring 176 is connected to the positive electrode wiring 174 at one end. Specifically, the third wiring 176 is connected to the positive electrode wiring 174 between the positive electrode terminal 51 of the battery 50 and the positive electrode side contactor 75 at one end. In the battery pack 40 shown in FIG. 1, the third wiring 176 is connected to the positive electrode wiring 174 between the positive electrode terminal 51 of the battery 50 and the current value detection unit 65 at one end.

[0033] Also, the third wiring 176 is connected to the first terminal 53 at the other end. The first terminal 53 is provided on the housing 41 of the battery pack 40. For example, as shown in FIG. 1, the first terminal 53 is attached to the outer surface 411 of the housing 41 and protrudes outward from the outer surface 411 of the housing 41. The first terminal 53 is connected to one terminal of a measuring device (not shown) for measuring the internal resistance of the battery 50. Examples of the measuring device for measuring the internal resistance of the battery 50 include a battery tester.

[0034] The fourth wiring 177 is connected to the negative electrode wiring 175 at one end. Specifically, the fourth wiring 177 is connected to the negative electrode wiring 175 between the negative electrode terminal 52 of the battery 50 and the negative electrode side contactor 76 at one end. Also, the fourth wiring 177 is connected to the second terminal 54 at the other end. The second terminal 54 is provided on the housing 41 of the battery pack 40. For example, as shown in FIG. 1, the second terminal 54 is attached to the outer surface 411 of the housing 41 and protrudes outward from the outer surface 411 of the housing 41. The second terminal 54 is connected to the other terminal of a measuring device for measuring the internal resistance of the battery 50. As described above, examples of the measuring device for measuring the internal resistance of the battery 50 include a battery tester.

[0035] 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, and an alternating constant current with a frequency of 1 kHz is applied to the battery 50 through the third wiring 176 and the fourth wiring 177, and the internal resistance of the battery 50 is calculated from the voltage value of the alternating voltage meter included in the battery tester.

[0036] As shown in FIG. 1, the battery pack 40 further includes a fuse 95. The fuse 95 is provided in the third wiring 176 and cuts off the third wiring 176 when an overcurrent flows through the third wiring 176. Thereby, even if the third wiring 176 and the fourth wiring 177 come into contact with each other and an overcurrent flows through the electric circuit constituted by the battery 50, the third wiring 176, and the fourth wiring 177, the fuse 95 can protect the electric circuit of the battery pack 40 by cutting off the third wiring 176.

[0037] The fuse 95 may be provided in the fourth wiring 177 instead of the third wiring 176. Alternatively, the fuse 95 may be provided in both the third wiring 176 and the fourth wiring 177. Even in this case, the fuse 95 can protect the electric circuit of the battery pack 40 by cutting off at least one of the third wiring 176 and the fourth wiring 177.

[0038] As described above, according to the battery pack 40 according to 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. 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 for example, an alternating constant current with a frequency of 1 kHz is applied to the battery 50 through the third wiring 176 and the fourth wiring 177, so that the internal resistance of the battery 50 can be calculated from the voltage value of the alternating voltage meter. Thereby, the battery pack 40 according to the present embodiment does not require 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 with the battery pack 40 alone.

[0039] Also, at one end, the third wiring 176 is connected to the positive electrode wiring 174 between the positive electrode terminal 51 of the battery 50 and the positive electrode side contactor 75 (the current value detection unit 65 in the battery pack 40 shown in FIG. 1). At one end, the fourth wiring 177 is connected to the negative electrode wiring 175 between the negative electrode terminal 52 of the battery 50 and the negative electrode side contactor 76. Therefore, it is possible to suppress the resistance components of the positive electrode side contactor 75, the negative electrode side contactor 76, and the current value detection unit 65 from entering, that is, to suppress the influence of the resistance components of the positive electrode side contactor 75, the negative electrode side contactor 76, and the current value detection unit 65, and it is possible to simply diagnose the degree of deterioration of the internal resistance of the battery 50 with the battery pack 40 alone.

[0040] Since the battery pack 40 according to the present embodiment has the first terminal 53 and the second terminal 54 as service ports capable of constantly detecting a high voltage, not only in the production process of the battery pack 40, but also after the battery pack 40 is mounted on the hybrid system 10 and provided in the market, it is possible to simply diagnose the degree of deterioration of the internal resistance of the battery 50 with the battery pack 40 alone.

[0041] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the scope of the claims. The configurations of the above embodiments can be partially omitted or arbitrarily combined differently from the above.

Explanation of reference numerals

[0042] 1: Engine, 2: Motor generator, 10: Hybrid system, 40: Battery pack, 41: Housing, 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, 95: Fuse, 150: ECU, 174: Positive wiring, 175: Negative wiring, 176: Third wiring, 177: Fourth wiring, 181: Signal line, 182: Signal line, 183: Signal line, 184: Signal line, 193: Signal line, 411: Outer surface

Claims

1. A battery pack mounted in a hybrid system, comprising: a housing; a battery provided inside the housing for supplying power to a motor generator of the hybrid system; a contact 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, for opening and closing 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; a second terminal connected to an end of the fourth wiring and provided on the housing, and connected to the other terminal of the measuring device; a fuse provided on the third wiring for cutting off the third wiring when an overcurrent flows through the third wiring; A battery pack characterized by comprising the above.

2. The contact includes: a first contact provided on the first wiring for opening and closing the first wiring; a second contact provided on the second wiring for opening and closing the second wiring; The third wiring is connected to the first wiring between the positive electrode and the first contact, The fourth wiring is connected to the second wiring between the negative electrode and the second contact. The battery pack according to claim 1.

3. Each of the first terminal and the second terminal is attached to an outer surface of the housing. The battery pack according to claim 1.

4. Each of the first terminal and the second terminal protrudes outward from the outer surface. The battery pack according to claim 3.

5. The battery pack according to any one of claims 1 to 4, further comprising a fuse provided on the fourth wiring for cutting off the fourth wiring when an overcurrent flows through the fourth wiring.

6. A battery pack mounted in a hybrid system, comprising: a housing; a battery provided inside the housing for supplying power to a motor generator of the hybrid system; ​ A contact 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, for opening and closing 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 provided at an end of the third wiring and provided in the housing, and connected to one terminal of a measuring device for measuring the internal resistance of the battery; A second terminal provided at an end of the fourth wiring and provided in the housing, and connected to the other terminal of the measuring device; A fuse provided in the fourth wiring, for interrupting the fourth wiring when an overcurrent flows through the fourth wiring; A battery pack, characterized by comprising the above.

7. The contact includes: A first contact provided in the first wiring for opening and closing the first wiring; A second contact provided in the second wiring for opening and closing the second wiring; The battery pack according to claim 6, characterized in that the third wiring is connected to the first wiring between the positive electrode and the first contact, and the fourth wiring is connected to the second wiring between the negative electrode and the second contact.

8. The battery pack according to claim 6, characterized in that each of the first terminal and the second terminal is attached to the outer surface of the housing.

9. The battery pack according to claim 8, characterized in that each of the first terminal and the second terminal protrudes outward from the outer surface. ​ ​

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