Battery pack

Abstract

To provide a battery pack capable of performing battery deterioration diagnosis by itself.SOLUTION: A battery pack 40 includes: a battery 50 which supplies electric power to a motor 2 of a hybrid system 10; a resistor 45 which is electrically connected to the battery 50 by an electric circuit; a switch 46 which is provided in an electric circuit 174 between the battery 50 and resistor 45 to open and close the electric circuit 174 between the battery 50 and the resistor 45; and a control part 85 which executes control to close the switch 46 in response to an input signal 86 and diagnoses the degree of degradation of the battery 50 based on the voltage variation of the battery 50 when current flows from the battery 50 to the resistor 45.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Hybrid systems that use an engine, a motor, and a battery in combination have been developed for industrial machinery, automobiles, etc. in response to demands for low pollution and fossil fuel conservation. A 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 hybrid systems, a battery pack including, for example, a lithium-ion battery is used as a power source for driving the motor. Lithium-ion batteries tend to deteriorate over time, resulting in a decrease in their full charge capacity after long-term storage or use. For example, in automobiles such as passenger cars with hybrid systems, the degree of deterioration of the lithium-ion battery can be easily diagnosed periodically during vehicle inspections using a deterioration diagnosis device.

[0004] However, industrial machinery with hybrid systems does not have the opportunity for periodic inspections such as vehicle inspections, making it difficult to periodically diagnose the degree of deterioration of lithium-ion batteries. For example, users of industrial machinery with hybrid systems must separately purchase expensive battery evaluation devices such as battery deterioration diagnosis devices in order to diagnose the degree of deterioration of lithium-ion batteries themselves. As such, because it is difficult to periodically diagnose the degree of deterioration of lithium-ion batteries in industrial machinery with hybrid systems, there is a problem in that it is unclear to users when to replace the lithium-ion batteries.

[0005] Patent Document 1 discloses a cell deterioration diagnosis method for a vehicle battery. Patent Document 2 discloses a battery state determination system and a battery state determination method that can determine the state of deterioration of a battery mounted on a vehicle in a server device. Patent Document 3 discloses a secondary battery deterioration determination device and a deterioration determination method that are realized by an ECU (Engine Control Unit) mounted on an electrically powered vehicle such as an electric vehicle or a hybrid vehicle.

[0006] However, in the technologies described in Patent Documents 1, 2, and 3, a control device or a detection device for detecting physical quantities (such as current and voltage) related to the battery state is installed in the vehicle, and is required separately from the battery pack. Therefore, there is a problem that it is difficult to perform battery degradation diagnosis using the battery pack alone. In other words, there is a problem that battery degradation diagnosis can only be performed when the battery pack is installed in a hybrid system. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-257372 [Patent Document 2] Patent Publication No. 2021-86654 [Patent Document 3] International Publication No. 2011 / 125213 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above circumstances, and has an object to provide a battery pack that can perform deterioration diagnosis of the battery by itself. [Means for solving the problem]

[0009] A first aspect of the present invention is a battery pack mounted on a hybrid system, comprising: a battery that supplies power to a motor of the hybrid system; a resistor electrically connected to the battery by an electric circuit; a switch provided in the electric circuit between the battery and the resistor and that opens and closes the electric circuit between the battery and the resistor; and a control unit that controls to close the switch in response to an input signal and diagnoses the degree of deterioration of the battery based on voltage fluctuations of the battery when current flows from the battery to the resistor.

[0010] According to a first aspect of the present invention, a resistor is provided in a battery pack and is electrically connected to a battery via an electric circuit. A switch is provided in the electric circuit between the battery and the resistor and opens and closes the electric circuit between the battery and the resistor. When the switch closes the electric circuit between the battery and the resistor, a current flows from the battery to the resistor. A control unit provided in the battery pack controls to close the switch in response to an input signal and diagnoses the degree of battery degradation based on the voltage fluctuation of the battery when the current flows from the battery to the resistor. This allows the battery pack according to the first aspect of the present invention to diagnose the deterioration of the battery provided in the battery pack by itself. Furthermore, since the battery pack according to the first aspect of the present invention can diagnose the deterioration of the battery by itself, the deterioration of the battery can be diagnosed by a signal input to the control unit at any time. For example, even when there is no opportunity for a periodic inspection such as a vehicle inspection, the deterioration of the battery can be diagnosed at any time. This makes it clearer when to replace the battery provided in the battery pack.

[0011] A second aspect of the present invention is a battery pack according to the first aspect of the present invention, characterized in that the control unit executes control to automatically open the switch when a predetermined time has elapsed since the switch was closed.

[0012] According to the second aspect of the present invention, the control unit can suppress the occurrence of an over-discharge abnormality in the battery.

[0013] A third aspect of the present invention is a battery pack according to the first or second aspect of the present invention, characterized in that the control unit has an internal circuit built therein that detects a voltage value of the battery.

[0014] According to the third aspect of the present invention, even if a separate detector for detecting the voltage value of the battery is not provided, the control unit can detect the voltage value of the battery using an internal circuit built into the control unit itself, thereby simplifying the structure of the battery pack and enabling the battery pack to be made smaller.

[0015] A fourth aspect of the present invention is a battery pack according to any one of the first to third aspects of the present invention, further comprising: a positive contactor provided in the electrical circuit between the positive terminal of the battery and the resistor, for opening and closing the electrical circuit between the positive terminal and the resistor; and a negative contactor provided in the electrical circuit between the negative terminal of the battery and the resistor, for opening and closing the electrical circuit between the negative terminal and the resistor, wherein the switch is provided in at least one of the electrical circuit between the positive contactor and the resistor and the electrical circuit between the negative contactor and the resistor.

[0016] According to a fourth aspect of the present invention, a switch that opens and closes the electric circuit between the battery and the resistor is provided in at least one of the electric circuit between the positive contactor and the resistor and the electric circuit between the negative contactor and the resistor. Therefore, even if an abnormality such as an overcurrent occurs in the electric circuit, the electric circuit upstream of the switch from the battery side is interrupted by opening at least one of the positive contactor and the negative contactor. This improves the safety of the battery pack.

[0017] A fifth aspect of the present invention is the battery pack of the fourth aspect of the present invention, further comprising a current value detection unit provided in the electric circuit and detecting a current value flowing through the electric circuit, wherein the control unit, when detecting an overcurrent abnormality based on the current value acquired from the current value detection unit, executes control to open the switch and executes control to open at least one of the positive side contactor and the negative side contactor.

[0018] According to a fifth aspect of the present invention, when the control unit detects an overcurrent abnormality based on the current value acquired from the current value detection unit, the control unit executes control to open the switch. Furthermore, when the control unit detects an overcurrent abnormality based on the current value acquired from the current value detection unit, the control unit executes control to open at least one of the positive contactor and the negative contactor. This allows the control unit to more reliably interrupt the electric circuit by opening at least one of the positive contactor and the negative contactor, even if, for example, the switch is welded and cannot be opened. This further improves the safety of the battery pack.

[0019] A sixth aspect of the present invention is a battery pack according to any one of the first to fifth aspects of the present invention, characterized in that the control unit has a memory unit that stores data on the voltage fluctuations, and diagnoses the degree of deterioration based on the data stored in the memory unit.

[0020] According to the sixth aspect of the present invention, the control unit diagnoses the degree of deterioration based on data on battery voltage fluctuations stored in the memory unit, thereby enabling the degree of battery deterioration to be estimated with higher accuracy and making it possible to more clearly determine the timing for battery replacement. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a battery pack that can perform deterioration diagnosis of the battery by itself. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a block diagram showing a hybrid system equipped with a battery pack according to an embodiment of the present invention. [Figure 2] 4 is a flowchart illustrating an example of an operation of a battery deterioration diagnosis executed by the battery pack according to the present embodiment. [Figure 3] 10 is a graph showing an example of the behavior of the voltage fluctuation of a battery when a current flows from the battery toward a resistor. [Figure 4] 1 is a graph showing an example of the transition of the degree of deterioration of a battery depending on the number of years the battery has been used. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The embodiments described below are preferred examples of the present invention, and therefore various technically preferable limitations are applied thereto, but the scope of the present invention is not limited to these aspects unless otherwise specified in the following description to the effect that the present invention is particularly limited. Furthermore, in each drawing, similar components are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0024] FIG. 1 is a block diagram showing a hybrid system equipped with a battery pack according to an embodiment of the present invention. 1 includes an engine 1, a motor generator 2, and a battery pack 40. The motor generator 2 of this embodiment is an example of the "motor" of the present invention.

[0025] The engine 1 is, for example, a multi-cylinder diesel engine such as a turbocharged, high-output, three-cylinder or four-cylinder engine. However, the engine 1 is not limited to a diesel engine. The engine 1 has an ECU (Engine Control Unit) 150. The ECU 150 controls the operation of the engine 1 and also controls the motor generator 2 by communicating with the motor generator 2 via, for example, a CAN (Controller Area Network).

[0026] The motor generator 2 runs on power supplied from the battery pack 40 to support the engine 1 when power is needed, such as when starting or accelerating the industrial machinery or the like in which the hybrid system 10 is installed. The hybrid system 10 is installed in industrial machinery or the like, including construction machinery such as forklifts and agricultural machinery such as tractors. The motor generator 2 also generates electricity by converting the kinetic energy of the industrial machinery or the like in which the hybrid system 10 is installed into electrical energy using regenerative braking or the like. The motor generator 2 has a built-in inverter. 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.

[0027] The battery pack 40 includes a battery 50, a resistor 45, a switch 46, and a BMU (Battery Management Unit) 85. 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 includes a positive terminal 51 and a negative terminal 52. An example of the battery 50 is a 48V high-voltage lithium ion battery (LiB). However, the battery 50 is not limited to a lithium ion battery. Furthermore, the voltage of the battery 50 is not limited to 48V and may be 48V or higher.

[0028] The resistor 45 is electrically connected to the battery 50 by an electric circuit. Specifically, as shown in FIG. 1, the resistor 45 is connected to a positive electrode wiring 174 connected to the positive electrode terminal 51 of the battery 50, and is also connected to a negative electrode wiring 175 connected to the negative electrode terminal 52 of the battery 50. In other words, the positive electrode wiring 174 is a wiring that electrically connects the positive electrode terminal 51 of the battery 50 and the resistor 45. The negative electrode wiring 175 is a wiring that electrically connects the negative electrode terminal 52 of the battery 50 and the resistor 45. The motor generator 2 is connected to a positive electrode branch wiring 176 that branches off from the positive electrode wiring 174, and is also connected to a negative electrode branch wiring 177 that branches off from the negative electrode wiring 175. In other words, as shown in FIG. 1, the electric circuit in which the resistor 45 and the motor generator 2 are connected to the battery 50 constitutes a parallel circuit.

[0029] The resistor 45 is used to discharge the battery 50, i.e., to cause current to flow from the battery 50, when the BMU 85 diagnoses the degree of deterioration of the battery 50. This will be described in detail later. The BMU 85 of this embodiment is an example of the "control unit" of the present invention.

[0030] The switch 46 is provided in an electric circuit between the battery 50 and the resistor 45. Specifically, as shown in FIG. 1 , the switch 46 is provided in the positive electrode wiring 174. That is, the electric circuit between the battery 50 and the resistor 45 includes the positive electrode wiring 174. More specifically, the switch 46 is provided in the positive electrode wiring 174 between the positive electrode side contactor 75 and the resistor 45. The switch 46 may also be provided in the negative electrode wiring 175. In this case, the electric circuit between the battery 50 and the resistor 45 includes the negative electrode wiring 175. More specifically, the switch 46 may also be provided in the negative electrode wiring 175 between the negative electrode side contactor 76 and the resistor 45.

[0031] The switch 46 is electrically connected to the BMU 85 by a signal line 185, and opens and closes the electric circuit between the battery 50 and the resistor 45, i.e., the positive wiring 174, based on a control signal transmitted from the BMU 85 through the signal line 185.

[0032] The battery pack 40 further includes a positive contactor 75, a negative contactor 76, a current value detection unit 65, and a fuse 95. The positive contactor 75 is provided in an electric circuit, i.e., a positive wiring 174, between the positive terminal 51 of the battery 50 and the resistor 45. The positive contactor 75 is electrically connected to the ECU 150 by a signal line 181, and opens and closes the positive wiring 174 based on a control signal transmitted from the ECU 150 through the signal line 181.

[0033] The positive electrode contactor 75 may be electrically connected to the BMU 85. In this case, the positive electrode contactor 75 opens and closes the positive electrode wiring 174 based on a control signal transmitted from the BMU 85.

[0034] The negative contactor 76 is provided in the electric circuit between the negative terminal 52 of the battery 50 and the resistor 45, i.e., in the negative wiring 175. The negative contactor 76 is electrically connected to the BMU 85 by a signal line 182, and opens and closes the negative wiring 175 based on a control signal transmitted from the BMU 85 through the signal line 182.

[0035] The negative contactor 76 may be electrically connected to the ECU 150. In this case, the negative contactor 76 opens and closes the negative wiring 175 based on a control signal transmitted from the ECU 150.

[0036] The BMU 85 is electrically connected to the battery 50 via a signal line 183, and detects the voltage value of the battery 50 based on a signal transmitted from the battery 50 via the signal line 183. Specifically, the BMU 85 uses an internal circuit built into the BMU 85 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 in the battery 50 based on the signal transmitted from the battery 50 via 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 via the signal line 183, and detects an overcharge abnormality and an overdischarge abnormality.

[0037] The BMU 85 is electrically connected to the current value detection unit 65 via a signal line 184, and acquires a 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 value of a current flowing through the positive electrode wiring 174. In other words, the BMU 85 acquires the value of a current flowing through the positive electrode wiring 174 from the current value detection unit 65 via the signal line 184. The BMU 85 detects an overcurrent abnormality based on the current value acquired from the current value detection unit 65 via the signal line 184. Alternatively, the BMU 85 detects an overtemperature abnormality based on a cell temperature acquired from a CMU (Cell Management Unit; not shown).

[0038] The BMU 85 is electrically connected to the ECU 150 via a signal line 193, and controls the negative contactor 76 based on a control signal transmitted from the ECU 150 via the signal line 193. The ECU 150 and the BMU 85 communicate with each other via, for example, a CAN, and monitor each other's status. The BMU 85 includes a storage unit 851 .

[0039] The fuse 95 is provided in the positive electrode wiring 174 between the current value detection unit 65 and the positive electrode contactor 75. The fuse 95 cuts off the electric circuit, that is, the positive electrode wiring 174, when an overcurrent flows through the positive electrode wiring 174.

[0040] However, when a battery pack is installed in industrial machinery, there is no opportunity for periodic inspections such as vehicle inspections, making it difficult to periodically diagnose the degree of deterioration of the battery (e.g., lithium-ion battery). As a result, the timing for battery replacement is unclear to the user. Furthermore, when physical quantities related to the battery state (such as current and voltage) are detected by a control device or detection device separate from the battery pack, it is difficult to diagnose battery deterioration using the battery pack alone. For example, battery deterioration diagnosis can only be performed when the battery pack is installed in a hybrid system.

[0041] In contrast, the BMU 85 of the battery pack 40 according to this embodiment executes control to close the switch 46 in response to an input signal 86 related to an instruction to perform a deterioration diagnosis on the battery 50. The input signal 86 is input to the BMU 85 by a serviceman or a user at any timing via a CAN, an analog switch, or the like. An example of the "any timing" is timing during a production process or an inspection process before the battery pack 40 is shipped from a factory. Another example of the "any timing" is timing during a regular or irregular inspection after the battery pack 40 is incorporated into the hybrid system 10 and installed in an actual vehicle.

[0042] It is preferable that the "arbitrary timing" after the battery pack 40 is mounted on the actual vehicle is a timing when the motor generator 2 is not operating. This allows the BMU 85 to diagnose the degree of deterioration of the battery 50 at a timing when the voltage of the battery 50 is relatively stable. This allows the BMU 85 to diagnose the degree of deterioration of the battery 50 more stably and with higher accuracy.

[0043] Next, when a predetermined time has elapsed since the BMU 85 closed the switch 46, the BMU 85 executes control to automatically open the switch 46. The "predetermined time" is, for example, approximately 8 seconds or more and 12 seconds or less. However, the "predetermined time" is not limited to 8 seconds or more and 12 seconds or less. Next, the BMU 85 diagnoses the degree of deterioration of the battery 50 based on the voltage fluctuation of the battery 50 when current flows from the battery 50 to the resistor 45. Note that the timing at which the BMU 85 diagnoses the degree of deterioration of the battery 50 does not necessarily have to be after the BMU 85 opens the switch 46, and may be before the BMU 85 opens the switch 46. In other words, the BMU 85 may diagnose the degree of deterioration of the battery 50 while the switch 46 is closed. The battery deterioration diagnosis sequence of this embodiment is stored in advance in the storage unit 851 of the BMU 85.

[0044] Next, an example of the operation of the battery pack 40 according to this embodiment to diagnose the degree of deterioration of the battery 50 will be described with reference to the drawings. FIG. 2 is a flowchart showing an example of the operation of the battery deterioration diagnosis executed by the battery pack according to this embodiment. FIG. 3 is a graph showing an example of the behavior of the voltage fluctuation of a battery when a current flows from the battery to a resistor. FIG. 4 is a graph showing an example of the transition of the degree of deterioration of a battery according to the number of years the battery has been in use.

[0045] 2, the BMU 85 determines whether or not a signal related to an instruction to perform a deterioration diagnosis on the battery 50 (i.e., the input signal 86: see FIG. 1) has been input to the BMU 85. An example of the timing at which the input signal 86 is input to the BMU 85 is as described above with reference to FIG.

[0046] When a signal related to an instruction to perform a deterioration diagnosis on the battery 50 is input to the BMU 85 (step S1: YES), in step S2, the BMU 85 executes control to close the switch 46. Subsequently, in step S3, the BMU 85 determines whether an overcurrent abnormality has been detected based on the current value acquired from the current value detection unit 65.

[0047] If the BMU 85 detects an overcurrent abnormality based on the current value acquired from the current value detection unit 65 (step S3: YES), in step S7, it executes control to open the switch 46 and also executes control to open at least one of the positive electrode side contactor 75 and the negative electrode side contactor 76. This allows the BMU 85 to more reliably interrupt the electric circuit. For example, even if the switch 46 is welded and cannot be opened, the BMU 85 can more reliably interrupt the electric circuit by opening at least one of the positive electrode side contactor 75 and the negative electrode side contactor 76. This further improves the safety of the battery pack 40.

[0048] On the other hand, if the BMU 85 does not detect an overcurrent abnormality (step S3: NO), in step S4, the BMU 85 determines whether a predetermined time has elapsed since the switch 46 was closed. As described above with reference to FIG. 1, the "predetermined time" is, for example, approximately 8 seconds or more and 12 seconds or less. However, the "predetermined time" is not limited to 8 seconds or more and 12 seconds or less.

[0049] If the predetermined time has not elapsed since the BMU 85 closed the switch 46 (step S4: NO), the BMU 85 executes the process described above with respect to step S3. On the other hand, if a predetermined time has elapsed since the BMU 85 closed the switch 46 (step S4: YES), the BMU 85 executes control to automatically open the switch 46 in step S5.

[0050] Subsequently, in step S6, the BMU 85 diagnoses the degree of deterioration of the battery 50 based on the voltage fluctuation of the battery 50 when a current flows from the battery 50 to the resistor 45.

[0051] 3, when a current flows from the battery 50 toward the resistor 45 for a predetermined time, the voltage value of the battery 50 detected by the BMU 85 fluctuates. The BMU 85 stores voltage fluctuation data of the battery 50 when a current flows from the battery 50 toward the resistor 45 in the storage unit 851 as a map M1.

[0052] The map M1 shown in Fig. 3 shows an example of the cell voltage of the battery 50 when the SOH (State Of Health) is 100% and an example of the cell voltage of the battery 50 when the SOH is 95%. Here, SOH is an index that indicates the degree of deterioration of the battery (i.e., the health or deterioration state), SOH = Fully charged capacity at degradation (Ah) / Initially fully charged capacity (Ah) x 100 In other words, SOH is the percentage of the full charge capacity of the battery at the time of deterioration (the rate of change in capacity) when the initial full charge capacity of the battery is taken as 100%.

[0053] 4, the BMU 85 estimates the deterioration level H of the battery 50 based on the voltage fluctuation data of the battery 50 in a map M1 stored in the storage unit 851. The deterioration level H of the battery 50 estimated by the BMU 85 is graphed as shown in FIG. 4. In the graph shown in FIG. 4, the vertical axis represents the capacity change rate (percent) of the battery, and the horizontal axis represents the number of years of use. The "capacity change rate" on the vertical axis of the graph shown in FIG. 4 corresponds to the SOH (State Of Health) described above.

[0054] This allows a service person or a user to check the deterioration degree H of the battery 50 as a graph, a numerical value, a warning light, or the like, on a display unit (not shown) provided in the battery pack 40 or an external display, etc., as necessary. For example, when the capacity change rate of the battery 50 becomes equal to or less than a predetermined value, the BMU 85 can execute a process to turn on an indicator lamp indicating the timing of battery 50 replacement, thereby warning the user that it is time to replace the battery 50.

[0055] As described above, in the battery pack 40 according to this embodiment, the resistor 45 is provided in the battery pack 40 and is electrically connected to the battery 50 by an electric circuit. The switch 46 is provided in the positive electrode wiring 174 between the battery 50 and the resistor 45 and opens and closes the positive electrode wiring 174 between the battery 50 and the resistor 45. Therefore, when the switch 46 closes the positive electrode wiring 174 between the battery 50 and the resistor 45, a current flows from the battery 50 to the resistor 45. The BMU 85 provided in the battery pack 40 executes control to close the switch 46 in response to the input signal 86, and diagnoses the degree of deterioration of the battery 50 based on the voltage fluctuation of the battery 50 when a current flows from the battery 50 to the resistor 45. As a result, the battery pack 40 according to this embodiment can perform deterioration diagnosis of the battery 50 provided in the battery pack 40 by itself. Furthermore, the battery pack 40 according to this embodiment can diagnose the deterioration of the battery 50 by itself, and therefore can diagnose the deterioration of the battery 50 at any timing based on a signal input to the BMU 85 (i.e., the input signal 86). For example, even if there is no opportunity for a periodic inspection such as a vehicle inspection, the degree of deterioration of the battery 50 can be diagnosed at any timing. This makes it clearer when to replace the battery 50 provided in the battery pack 40.

[0056] Furthermore, the BMU 85 executes control to automatically open the switch 46 after a predetermined time has elapsed since the switch 46 was closed, thereby making it possible to prevent the occurrence of an over-discharge abnormality in the battery 50.

[0057] Furthermore, according to the battery pack 40 of this embodiment, even if a separate detector for detecting the voltage value of the battery 50 is not provided, the BMU 85 can detect the voltage value of the battery 50 using an internal circuit built into the BMU 85 itself. This simplifies the structure of the battery pack 40, and allows the battery pack 40 to be made smaller.

[0058] Furthermore, a switch 46 that opens and closes the electric circuit between the battery 50 and the resistor 45 is provided in at least one of the positive wiring 174 between the positive contactor 75 and the resistor 45 and the negative wiring 175 between the negative contactor 76 and the resistor 45. Therefore, even if an abnormality such as an overcurrent occurs in the electric circuit, the electric circuit upstream of the switch 46 as viewed from the battery 50 is interrupted by opening at least one of the positive contactor 75 and the negative contactor 76. This improves the safety of the battery pack 40.

[0059] In addition, since the BMU 85 diagnoses the degree of deterioration based on the data of voltage fluctuations of the battery 50 stored in the memory unit 851, the degree of deterioration of the battery 50 can be estimated with higher accuracy, and the timing of replacing the battery 50 can be made clearer.

[0060] The above describes the embodiments of the present invention. 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. The configurations of the above embodiments can be partially omitted or arbitrarily combined in a different manner from the above. [Explanation of symbols]

[0061] 1: Engine, 2: Motor generator, 10: Hybrid system, 40: Battery pack, 45: Resistor, 46: Switch, 50: Battery, 51: Positive terminal, 52: Negative terminal, 65: Current detection unit, 75: Positive contactor, 76: Negative contactor, 85: BMU, 86: Input signal, 95: Fuse, 150: ECU, 174: Positive wiring, 175: Negative wiring, 176: Positive branch wiring, 177: Negative branch wiring, 181: Signal line, 182: Signal line, 183: Signal line, 184: Signal line, 185: Signal line, 193: Signal line, 851: Memory unit

Claims

1. A battery pack mounted on a hybrid system, a battery that supplies power to a motor generator of the hybrid system; a BMU electrically connected to the battery by a signal line, detecting a voltage value of the battery based on a signal transmitted from the battery through the signal line, and detecting an overcharge abnormality and an overdischarge abnormality; a resistor electrically connected to the battery by an electric circuit, connected to a positive wiring connected to a positive terminal of the battery, and connected to a negative wiring connected to a negative terminal of the battery; a positive electrode side contactor that is provided on the positive electrode wiring and opens and closes the positive electrode wiring; a negative electrode side contactor that is provided on the negative electrode wiring and opens and closes the negative electrode wiring; a switch provided in at least one of the positive wiring between the positive contactor and the resistor and the negative wiring between the negative contactor and the resistor, for opening and closing the electric circuit between the battery and the resistor; Equipped with the motor generator is connected to a positive electrode branch wiring branched from the positive electrode wiring between the positive electrode side contactor and the resistor, and is connected to a negative electrode branch wiring branched from the negative electrode wiring between the negative electrode side contactor and the resistor, the BMU has a storage unit that stores voltage fluctuation data of the battery for each SOH when a current flows from the battery toward the resistor for a predetermined time, and stores relationship data indicating a relationship between the age of the battery and the SOH of the battery at each age of the battery; when a signal related to an instruction to diagnose deterioration of the battery is input at a timing when the battery is not supplying the power to the motor generator, control is executed to close the switch, and the voltage fluctuation data of the battery when the current flows from the battery to the resistor is stored in the storage unit; When the predetermined time has elapsed since the switch was closed, control is executed to automatically open the switch; Next, based on the voltage fluctuation data accumulated in the memory unit, and the voltage fluctuation data and the relationship data stored in the memory unit, at least one of the SOH and the number of years of use of the battery to which the signal related to the deterioration diagnosis instruction has been input is estimated.

2. 2. The battery pack according to claim 1, wherein the BMU includes an internal circuit that detects the voltage value of the battery.

3. a current value detection unit provided in the electric circuit and detecting a value of a current flowing in the electric circuit; 2. The battery pack according to claim 1, wherein when the BMU detects an overcurrent abnormality based on the current value acquired from the current value detection unit, the BMU executes control to open the switch and executes control to open at least one of the positive electrode side contactor and the negative electrode side contactor.

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