Electric work machine and starting method for the same

Abstract

To provide an electric work machine that can prevent damage to an internal circuit of a battery pack due to the effect of inrush current at startup.SOLUTION: The electric work machine includes an electric circuit 21, a plurality of battery packs 22, etc., and a control unit 23. The electric circuit 21 includes a plurality of external relays 211, etc corresponding to the battery packs 22. The control unit 23 performs an external relay diagnosis process to diagnose whether contacts of the external relays 211 corresponding to the second and subsequent battery packs 22 are stuck. In the external relay diagnosis process, if voltages of positive and negative external terminals 223a, 223b of the battery packs 22 are equal to or greater than a threshold value, the control unit determines that the contacts of the external relays 211 are stuck. If a voltage between the positive and negative external terminals 223a, 223b of the battery packs 22 is lower than the threshold value, the control unit determines that the contacts of the external relay 221 are normal.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an electric working machine that operates with power supplied from a plurality of battery packs. [Background technology]

[0002] Conventionally, there has been provided an electric working machine that operates on power supply from a plurality of battery packs (assembled batteries). This type of electric working machine includes an electric device, an electric circuit electrically connected to the electric device, and a plurality of battery packs connected in parallel to the electric device via the electric circuit (see, for example, Patent Documents 1 and 2). In general, a battery pack (assembled battery) has an internal relay that opens and closes an internal circuit, and the battery pack itself is switched ON / OFF by opening and closing the internal relay. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 167024 [Patent Document 2] JP 2011-188789 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the internal relay of the battery pack is closed while the electric circuit is in a conductive state (conductive state), an inrush current acts on the internal relay, which may damage the internal circuit (internal relay).

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide an electric operating machine and a method for starting the electric operating machine that can prevent damage to the internal circuitry of the battery pack due to the influence of an inrush current at the time of startup. [Means for solving the problem]

[0006] The electric working machine according to the present invention includes an electric device, an electric circuit electrically connected to the electric device, a plurality of battery packs having positive and negative external terminals, the plurality of battery packs being sequentially connected to the electric device via the electric circuit and connected in parallel, and a control unit, the electric circuit including a plurality of external relays corresponding to each of the plurality of battery packs, the plurality of external relays opening and closing a circuit connecting the corresponding battery pack and the electric device, the control unit performs an external relay diagnosis process for diagnosing whether or not a contact of the external relay corresponding to the battery pack is stuck with an internal circuit of the battery pack in an open state before the battery pack is connected to the electric device, the control unit operates the internal circuit of the battery pack to be diagnosed in an open state in the external relay diagnosis process, and when a voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than a threshold value with the external relay corresponding to the battery pack in an open state, the control unit determines that the contact of the external relay is stuck, and when a voltage between the external terminals of the positive and negative electrodes of the battery pack is lower than the threshold value, the control unit determines that the contact of the external relay is normal.

[0007] The electric operating machine according to the present invention includes an electric device, an electric circuit electrically connected to the electric device, a plurality of battery packs having positive and negative external terminals, the plurality of battery packs being sequentially connected to the electric device via the electric circuit and connected in parallel, and a control unit, the electric circuit including a plurality of external relays corresponding to each of the plurality of battery packs, the plurality of external relays opening and closing a circuit connecting the corresponding battery pack and the electric device, the battery packs being configured to control a control circuit in an internal circuit of the battery pack. the control unit has a discharge circuit connecting a negative external terminal side and a positive external terminal side of a battery pack, the discharge circuit including a discharge resistor and a discharge relay connected in series, and when connecting the battery pack to the electrical device, the control unit performs a discharge relay diagnostic process to diagnose whether or not a contact of the discharge relay of the battery pack is stuck, and in the discharge relay diagnostic process, the control unit operates the external relay corresponding to the battery pack to be diagnosed to a closed state and operates the discharge relay of the battery pack to an open state, and determines that the contact of the discharge relay of the discharge circuit is stuck if the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than the threshold value and the voltage across the discharge circuit is equal to or lower than the threshold value, and determines that the contact of the discharge relay of the discharge circuit is normal if the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than the threshold value and the voltage across the discharge circuit is higher than the threshold value.

[0008] The method for starting an electric work machine according to the present invention includes an electric device, an electric circuit electrically connected to the electric device, and a plurality of battery packs having positive and negative external terminals, the battery packs being sequentially connected to the electric device via the electric circuit and connected in parallel, the electric circuit including a plurality of external relays corresponding to each of the plurality of battery packs, the plurality of external relays opening and closing a circuit connecting the corresponding battery pack and the electric device, the method for starting an electric work machine includes the steps of: before the battery pack is connected to the electric device, performing an external relay diagnostic process for diagnosing whether or not a contact of the external relay corresponding to the battery pack is stuck, with an internal circuit of the battery pack in an open state; in the external relay diagnostic process, the internal circuit of the battery pack to be diagnosed is operated to an open state, and with the external relay corresponding to the battery pack in an open state, if a voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than a threshold value, it is determined that the contact of the external relay is stuck, and if the voltage between the external terminals of the positive and negative electrodes of the battery pack is lower than the threshold value, it is determined that the contact of the external relay is normal.

[0009] The method for starting an electric operating machine according to the present invention includes an electric device, an electric circuit electrically connected to the electric device, and a plurality of battery packs having positive and negative external terminals, the plurality of battery packs being sequentially connected to the electric device via the electric circuit and connected in parallel, the electric circuit including a plurality of external relays corresponding to each of the plurality of battery packs, the plurality of external relays opening and closing a circuit connecting the corresponding battery pack and the electric device, the battery packs being a discharge circuit connecting an external terminal side of a negative electrode and an external terminal side of a positive electrode in an internal circuit of the battery pack, the discharge circuit including a discharge resistor and a discharge relay connected in series, the method for starting an electric operating machine includes the steps of: when connecting the battery pack to the electric device, a discharge relay diagnostic process is performed to diagnose whether or not a contact of the discharge relay of the battery pack is stuck, and in the discharge relay diagnostic process: The external relay corresponding to the battery pack to be diagnosed is operated to a closed state, and the discharge relay of the battery pack is operated to an open state.If the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or greater than the threshold value and the voltage across the discharge circuit is equal to or less than the threshold value, it is determined that the contacts of the discharge relay of the discharge circuit are stuck.If the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or greater than the threshold value and the voltage across the discharge circuit is higher than the threshold value, it is determined that the contacts of the discharge relay of the discharge circuit are normal. Effect of the Invention

[0010] According to the present invention, it is possible to prevent damage to the internal circuitry of the battery pack caused by the inrush current at the time of startup. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a side view of an electric operating machine according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a hydraulic system and an electrical system of the electric working machine according to the embodiment. [Diagram 3] FIG. 3 is an electrical system diagram of the electric operating machine according to the embodiment. [Figure 4] FIG. 4 is a process flow diagram of the diagnosis of whether or not the battery packs of the electric operating machine according to the embodiment can be connected in parallel. [Diagram 5] FIG. 5 is a process flow diagram of parallel connection processing of the battery packs of the electric operating machine according to the embodiment. [Figure 6] FIG. 6 is a table showing diagnostic conditions and results in each diagnostic process in the opening and closing operation diagnosis of the internal relay of the battery pack of the electric operating machine according to the embodiment. [Figure 7] FIG. 7 is a process flow diagram of the fault diagnosis of the electric operating machine according to the embodiment. [Figure 8]FIG. 8 is a process flow diagram of single connection processing of the battery pack of the electric operating machine according to the embodiment. [Figure 9] FIG. 9 is a process flow diagram of a charging mode for charging the battery pack of the electric operating machine according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an electric operating machine according to one embodiment of the present invention will be described with reference to the drawings.

[0013] As shown in FIG. 1, the electric working machine 1 is a self-propelled traveling type working machine and includes a traveling device 10.

[0014] The traveling device 10 has a traveling frame 100 and a traveling mechanism 101. The traveling frame 100 is a structure to which the traveling mechanism 101 is attached.

[0015] The traveling mechanisms 101 are provided on the left and right sides of the traveling frame 100. That is, a pair of traveling mechanisms 101 are arranged in the left-right width direction perpendicular to the forward and backward directions.

[0016] In this embodiment, the traveling mechanism 101 is a crawler type traveling mechanism. Specifically, the traveling mechanism 101 includes an idler 102, a drive wheel 103, a plurality of rollers 104, an endless annular crawler belt 105, and a traveling motor 106.

[0017] The idler 102 is disposed at the front of the traveling frame 100 in the forward direction. The drive wheel 103 is disposed at the rear of the traveling frame 100 in the backward direction. A plurality of rollers 104 are provided between the idler 102 and the drive wheel 103. The crawler belt 105 is wound around the idler 102, the drive wheel 103, and the rollers 104.

[0018] The traveling motor 106 rotates and drives the drive wheels 103. In this embodiment, a hydraulic motor is adopted as the traveling motor 106. Each of the pair of left and right traveling mechanisms 101 rotates the crawler belt 105 by driving the drive wheels 103 to rotate.

[0019] The electric work machine 1 according to this embodiment includes a work device 11 for performing a predetermined task. The electric work machine 1 also includes a swivel base 12 fixed to a traveling frame 100, a machine body 13 supported by the swivel base 12, and a cabin 14 supported by the machine body 13.

[0020] In this embodiment, the electric work machine 1 includes a dozer device 11a and a sieve as the work device 11. and a shovel device 11b.

[0021] The dozer device 11a is mounted in front of the traveling device 10. Specifically, the dozer device 11a includes a dozer plate 110a, a support arm 111a having a tip connected to the dozer plate 110a, the support arm 111a being connected to the traveling frame 100 via a shaft extending in the horizontal direction and capable of swinging up and down about the shaft, and a hydraulic cylinder 112a that swings the support arm 111a.

[0022] The shovel device 11b includes a boom 110b, an arm 111b, a bucket 112b that is a working tool, and hydraulic cylinders 113b, 114b, and 115b.

[0023] The boom 110b has a base end and a tip end. The base end of the boom 110b is pivotally connected to a swing bracket 130 (described later) via a first shaft S1 extending in a direction perpendicular to the up-down direction. Accordingly, the boom 110b rotates (pivots) about the first shaft S1, thereby allowing the tip end side to swing up and down.

[0024] The arm 111b has a base end and a tip end. The base end of the arm 111b is pivotally connected to the tip end of the boom 110b via a second shaft S2 extending in a direction perpendicular to the up-down direction. Accordingly, the arm 111b rotates (pivots) about the second shaft S2, allowing the tip end side to swing in the front-rear or up-down direction. The bucket 112b is connected to the tip end of the arm 111b so as to be capable of scooping and dumping operations.

[0025] The electric work machine 1 includes, as hydraulic cylinders of the working device 11, a boom cylinder 113b that swings the boom 110b, an arm cylinder 114b that swings the arm 111b, and a bucket cylinder 115b that performs scooping and dumping operations on the bucket 112b. The electric work machine 1 also includes, as a hydraulic cylinder, a swing cylinder 131 that swings the swing bracket 130.

[0026] The swivel base 12 is a swivel bearing having an inner ring and an outer ring, and the traveling frame 100 is connected to either the inner ring or the outer ring, and the machine body 13 is connected to the other of the inner ring or the outer ring. The swivel base 12 has a pinion attached to an output shaft of a swivel motor 120 (see FIG. 2) fixed to either the machine body 13 or the traveling frame 100, and an annular gear provided on the inner circumference of the inner ring or the outer circumference of the outer ring connected to the other of the machine body 13 or the traveling frame 100 meshed with each other. As a result, the swivel base 12 rotates the inner ring and the outer ring relatively around an axis extending in the vertical direction by driving the swivel motor 120, and rotates the machine body 13 connected to the other of the inner ring or the outer ring around an axis extending in the vertical direction. In this embodiment, a hydraulic motor is used for the swivel motor 120.

[0027] A swing bracket 130 is connected to the front part of the machine body 13, which is the front in the forward direction. Specifically, the swing bracket 130 is pivotally connected to the machine body 13 via a shaft extending in the vertical direction. This allows the swing bracket 130 to rotate (pivot) around the shaft extending in the vertical direction. In other words, the swing bracket 130 swings left and right due to the expansion and contraction of the swing cylinder 131. The machine body 13 supports the cabin 14, and the cabin 14 accommodates a seat 140 on which an operator sits, an operating means 141 for operating the electric work machine 1, a start switch for starting the electric work machine 1 (the traveling device 10 and the working device 11), a monitor 142 (see FIG. 2) as a notification means for notifying the operator of the operating state, etc.

[0028] As shown in FIG. 2, the electric work machine 1 includes a traveling device 10 (traveling mechanism 101), a working device 11 (a dozer device 11a or a shovel device 11b), and a swivel 12. The working device 11 is connected to a hydraulic cylinder 112a, In accordance with the provision of a plurality of hydraulic actuators such as 113b, 114b, 115b, 131 and hydraulic motors 106, 120, a hydraulic pump 15 is provided which supplies hydraulic oil to the plurality of hydraulic actuators 106, 112a, 113b, 114b, 115b, 120, 131. In this embodiment, in order to supply hydraulic oil to the plurality of hydraulic actuators 106, 112a, 113b, 114b, 115b, 120, 131, a multiple hydraulic pump is adopted for the hydraulic pump 15.

[0029] The hydraulic pump (multiple hydraulic pump) 15 is an electric type. That is, the electric work machine 1 includes an electric motor 16 that drives the hydraulic pump 15.

[0030] Assuming the above-mentioned configuration, the electric work machine 1 according to this embodiment includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, a plurality of battery packs 22... which are sequentially connected in parallel to the electric device 20 via the electric circuit 21, and a control unit 23. Furthermore, the electric work machine 1 includes a junction box 24 that houses all or a part of the electric circuit 21. Note that in Fig. 2, the electric circuit 21 is indicated by a dashed line, a signal system that transmits and receives control signals is indicated by a dashed line, and a hydraulic system is indicated by a dashed double-dashed line.

[0031] In this embodiment, the electric work machine 1 includes a plurality of electric devices 20. Specifically, the electric work machine 1 includes an inverter 20a for driving the electric motor 16 as the electric device 20 for output. That is, the electric work machine 1 includes the electric devices 20 for driving the work implements 11 (in this embodiment, a dozer device 11a and a shovel device 11b) for performing a predetermined work.

[0032] The electric work machine 1 includes, as other output electric equipment 20, a DC / DC converter 20b and a heater 20c for heating the cabin 14. Note that the other output electric equipment 20 here is an example, and is added depending on the specifications, functions, etc. of the electric work machine 1.

[0033] The electric work machine 1 includes a charging inlet for connecting to an external charging device (for example, a quick charger) as an input electric device 25. In this embodiment, in addition to the battery pack 22, a 12V battery 26 is connected to the DC / DC converter 20b.

[0034] As shown in FIG. 3, the electric devices 20 and 25, whether for input or output, have a positive electrode connection terminal PE and a negative electrode connection terminal NE.

[0035] The electric circuit 21 includes a plurality of external relays 211... corresponding to the plurality of battery packs 22.... Specifically, the electric circuit 21 includes a plurality of primary circuits 210... electrically and physically connected to the plurality of battery packs 22..., each of which is electrically connected to an output electric device 20 (the inverter 20a, the DC / DC converter 20b, the heater 20c) and a charging inlet 25 which is an input electric device, and a plurality of external relays 211... which open and close each of the plurality of primary circuits 210.

[0036] In this embodiment, as described above, the electric work machine 1 includes a plurality of output electric devices 20 (the inverter 20a, the DC / DC converter 20b, the heater 20c) and an input electric device, the charging inlet 25. Accordingly, the electric circuit 21 includes a plurality of secondary circuits 212... electrically and physically connected to the plurality of output electric devices 20 (the inverter 20a, the DC / DC converter 20b, the heater 20c) and the input electric device (the charging inlet) 25.

[0037] Specifically, the electric circuit 21 includes a plurality of batteries connected to the plurality of battery packs 22. the primary circuits 210..., a common circuit 213 to which the multiple primary circuits 210... are electrically and physically connected, and multiple secondary circuits 212... electrically and physically connected to the common circuit 213, each of which is connected to a separate output electrical device 20 (inverter 20a, DC / DC converter 20b, heater 20c) and a charging inlet 25 which is an input electrical device.

[0038] The electric circuit 21 connects the plurality of battery packs 22 in parallel by connecting the plurality of primary circuits 210 to the common circuit 213. More specifically, the electric circuit 21 includes, as the plurality of primary circuits 210, a plurality of positive primary circuits 210a connected to later-described positive output terminals (external terminals on the positive electrode side) 223a of each of the plurality of battery packs 22, and a plurality of negative primary circuits 210b connected to later-described negative output terminals (external terminals on the negative electrode side) 223b of each of the plurality of battery packs 22.

[0039] The electric circuit 21 also includes, as the common circuit 213, a positive common circuit 213a to which the multiple positive primary circuits 210a are connected, and a negative common circuit 213b to which the multiple negative primary circuits 210b are connected. The electric circuit 21 also includes, as the multiple secondary circuits 212, a multiple positive secondary circuits 212a connected to the positive common circuit 213a, each of which is connected to a positive connection terminal PE of a separate output electric device 20 (inverter 20a, DC / DC converter 20b, heater 20c) and an input electric device (charging inlet) 25, and a multiple negative secondary circuits 212b connected to the negative common circuit 213b, each of which is connected to a negative connection terminal NE of a separate output electric device 20 (inverter 20a, DC / DC converter 20b, heater 20c) and an input electric device (charging inlet) 25.

[0040] The external relay 211 is disposed in each of the multiple positive primary circuits 210a... or each of the multiple negative primary circuits 210b.... In this embodiment, the external relay 211 is disposed in each of the multiple negative primary circuits 210b.... The external relay 211 is a relay switch with an a-contact. That is, the external relay 211 is a relay switch that normally maintains the electric circuit 21 in an open (disconnected) state and closes (connects) the electric circuit 21 when activated. The external relay 211 operates upon receiving an instruction from the control unit 23 (ECU 23a) to open or close the electric circuit 21.

[0041] As a result, the multiple external relays 211 can open and close a circuit (electrical system) connecting the multiple battery packs 22 and the output electric devices 20 (the inverter 20a, the DC / DC converter 20b, the heater 20c). The multiple external relays 211 can also open and close a circuit (electrical system) connecting the multiple battery packs 22 and the charging inlet 25, which is an input electric device.

[0042] Each of the battery packs 22 has an internal circuit 222 and an internal relay 220 that opens and closes the internal circuit 222. Each of the battery packs 22 also has a battery cell (single battery) 221. Specifically, each of the battery packs 22 has a plurality of battery cells 221. That is, the battery packs 22 are so-called assembled batteries. Accordingly, each of the battery packs 22 has an internal circuit 222 that includes a plurality of battery cells 221 connected in series. That is, the internal circuit 222 is a series circuit in which the plurality of battery cells 221 and the internal relay 220 are connected in series.

[0043] The battery pack 22 has positive and negative external terminals 223a, 223b which are the ends of the internal circuit 222. That is, the battery pack 22 has a positive output terminal 223a and a negative output terminal 223b as external terminals. The positive output terminal 223a is electrically connected to the positive terminal of the battery cell 221 at one end of the multiple battery cells 221 connected in series. The negative output terminal 223b is electrically connected to the negative terminal of the battery cell 221 at the other end of the plurality of battery cells 221 connected in series.

[0044] Specifically, the internal circuit 222 has a plurality of battery cells 221... connected in series, a first circuit 222a connecting the positive terminal of the battery cell 221 at one end of the plurality of battery cells 221... connected in series to the positive output terminal 223a, the first circuit 222a including a first internal relay 220a on the positive side as the internal relay 220, and a second circuit 222b connecting the negative terminal of the battery cell 221 at the other end of the plurality of battery cells 221... connected in series to the negative output terminal 223b, the second circuit 222b including a second internal relay 220b on the negative side as the internal relay 220.

[0045] The internal relay 220 (the first internal relay 220a and the second internal relay 220b) is a contact a relay switch. That is, the internal relay 220 (the first internal relay 220a and the second internal relay 220b) is a relay switch that normally opens the internal circuit 222 and closes the internal circuit 222 when activated.

[0046] In this embodiment, the internal circuit 222 includes a precharge circuit 224 connected in parallel to the first internal relay 220a of the first circuit 222a. The precharge circuit 224 is a circuit connected to the first circuit 222a on the primary side (upstream) and secondary side (downstream) of the first internal relay 220a, and includes a precharge resistor 224a and a precharge relay 224b that opens and closes the precharge circuit 224. The precharge relay 224b is a relay switch of a contact a. That is, the precharge relay 224b is a relay switch that normally opens the precharge circuit 224 and closes the precharge circuit 224 when activated. In the precharge circuit 224, the precharge resistor 224a and the precharge relay 224b are connected in series. That is, the precharge resistor 224a and the precharge relay 224b form a series-connected circuit, and the precharge circuit 224 including this series-connected circuit (the precharge resistor 224a and the precharge relay 224b) is connected in parallel to the first internal relay 220a.

[0047] The battery pack 22 (internal circuit 222) includes a discharge circuit 225. The discharge circuit 225 is connected to the first circuit 222a and the second circuit 222b. Specifically, the discharge circuit 225 is a so-called discharge circuit, and is a circuit that spans the downstream side of the first internal relay 220a in the first circuit 222a and the upstream side of the second internal relay 220b in the second circuit 222b. Note that the terms "upstream side" and "downstream side" herein are expressions based on the direction of current (electrical flow) based on the multiple battery cells 221 (the multiple battery cells 221 connected in series) that constitute the internal circuit 222 of the battery pack 22.

[0048] The discharge circuit 225 includes a discharge resistor 225a and a discharge relay 225b that opens and closes the discharge circuit 225. The discharge relay 225b is a relay switch with an a-contact. That is, the discharge relay 225b is a relay switch that normally opens the discharge circuit 225 (disconnects) and closes the discharge circuit 225 (connects) when activated. In the discharge circuit 225, the discharge resistor 225a and the discharge relay 225b are connected in series.

[0049] The control unit 23 controls the opening and closing of the electric circuit 21 and the internal circuit 222 of the battery pack 22. That is, the control unit 23 controls the opening and closing of the internal relays 220 (first internal relay 220a and second internal relay 220b), the pre-charge relay 224b, and the discharge relay 225b in the internal circuit 222 of the battery pack 22, in addition to the external relay 211 in the electric circuit 21. The electric working machine 1 has a drive mode for driving the device 20 and a charge mode for charging the battery pack 22. More specifically, as shown in FIG. 2, the electric working machine 1 includes, as the control unit 23, an electronic control unit (hereinafter referred to as ECU) 23a for controlling the entire electric working machine 1. In this embodiment, since the battery pack 22, which is a battery pack, is adopted as the power supply source, the electric working machine 1 includes, as the control unit 23, a battery management system (hereinafter referred to as BMS) 23b for monitoring and controlling the battery pack 22. Accordingly, in this embodiment, the ECU 23a and BMS 23b constituting the control unit 23 operate the opening and closing of relay switches (the external relay 211 in the electric circuit 21, the internal relay 220 (the first internal relay 220a and the second internal relay 220b) in the internal circuit 222 of the battery pack 22, the pre-charge relay 224b, and the discharge relay 225b). Specifically, the ECU 23a issues an instruction to open or close the relay switch, and the BMS 23b receives the instruction from the ECU 23a and causes the relay switch to be opened or closed.

[0050] In this embodiment, the ECU 23a sequentially connects the multiple battery packs 22 to the electric device 20. Accordingly, the multiple battery packs 22 include a first battery pack 22 that is the battery pack that is set to be first in the order of being connected to the electric device 20, and a second battery pack 22 that is the battery pack that is set to be second or later in the order of being connected to the electric device 20. Specifically, the multiple battery packs 22 are sequentially connected to the electric device 20 and are finally connected in parallel, so that each of the battery packs 22 supplies power to the electric device 20.

[0051] Accordingly, here, of the multiple battery packs 22, the battery pack 22 that is first connected to the electric device 20 is referred to as a first battery pack, and the battery pack 22 that is second or later connected to the electric device 20 is referred to as a second battery pack. When there are two battery packs 22, there is one first battery pack 22 and one second battery pack 22, but when there are three or more battery packs 22, there is one first battery pack 22 and two or more second battery packs 22.

[0052] On this premise, the ECU 23a is configured to be able to specify whether or not diagnosis of the opening / closing operation of the internal relay 220 of the second battery pack 22 connected to the electric device 20 is required. Also, the ECU 23a is configured to be able to specify whether or not precharging is required in the precharge circuit 224 of the second battery pack 22. Furthermore, the ECU 23a is configured to be able to specify whether or not the first internal relay 220a and the second internal relay 220b as the internal relay 220 are simultaneously closed when the second battery pack 22 is connected to the electric device 20 (when performing a first post-stage process described later).

[0053] Regarding these designations, preset contents (unchangeable prescribed information) are stored in a storage unit included in the ECU 23a, or input contents (as changeable information) are stored by setting via an input device. Note that the input device may be a device dedicated to input, but for example, the monitor 142 as the notification means may be configured with a touch panel, and input may be made via the monitor 142.

[0054] In this embodiment, the above designation is stored in a storage unit of the ECU 23a as preset contents (unchangeable prescribed information). Specifically, the storage unit of the ECU 23a stores a designation (instruction) that diagnosis is unnecessary for a designation regarding whether or not the opening / closing operation of the internal relay 220 of the second battery pack 22 needs to be diagnosed. Also, the storage unit of the ECU 23a stores a designation (instruction) that precharging is unnecessary for a designation regarding whether or not precharging is required in the precharge circuit 224 of the second battery pack 22. Furthermore, the storage unit of the ECU 23a stores a designation (instruction) that precharging is unnecessary for a designation regarding whether or not the first internal relay 220a and the second internal relay 220b as the internal relay 220 are simultaneously closed when the second battery pack 22 is connected to the electric device 20 (when performing a first post-stage process described later).

[0055] The electric work machine 1 is equipped with a start switch, and is configured to start and stop by turning the start switch ON / OFF. In this embodiment, when the start switch is turned ON, the control unit 23 (ECU 23a) executes a drive mode in which the electric device 20 is driven by power supplied from the battery pack 22. That is, the ECU 23a performs a start process when the start switch is turned ON.

[0056] The BMS 23b is a control device specialized for the battery pack 22, and the ECU 23a is a higher-level control device of the BMS 23b. That is, the BMS 23b executes control such as opening and closing of the internal relay 220 (220a, 220b), but is under the control of the ECU 23a and also follows instructions and commands from the ECU 23a.

[0057] The BMS 23b is provided for each battery pack 22, and monitors (measures) the overall temperature, current, and voltage of the corresponding battery pack 22. The overall current and voltage are the current and voltage between the positive output terminal 223a and the negative output terminal 223b, which are external terminals of each battery pack 22. In this embodiment, the BMS 23b is intended to monitor (measure) the entire battery pack 22, but in addition to monitoring (measurement) the entire battery pack 22, the BMS 23b may also monitor (measure) the temperature, voltage, and current of the multiple battery cells 221... installed therein.

[0058] Although not shown in the figure, the junction box 24 is a housing having an openable and closable door, and houses the electric circuit 21. In this embodiment, the junction box 24 houses downstream portions of the multiple primary circuits 210 (210b, 210a), the common circuit 213 (213b, 213a), and upstream portions of the multiple secondary circuits 212 (212b, 212a). That is, the junction box 24 houses therein the connection portions of the multiple primary circuits 210 (210b, 210a) to the common circuit 213 (213b, 213a) and the connection portions of the multiple secondary circuits 212 (212b, 212a) to the common circuit 213 (213b, 213a).

[0059] In addition, an external relay 211 provided on the primary circuit 210 (210b, 210a) is also provided inside the junction box 24. Accordingly, the multiple external relays 211 are provided in the middle of the multiple primary circuits 210 (negative primary circuit 210b) and are provided inside the junction box 24.

[0060] In this embodiment, the electric circuit 21 includes a negative primary circuit 210b and a positive primary circuit 210a as the primary circuit 210, and the external relay 211 is provided only in the negative primary circuit 210b. Accordingly, the external relay 211 is provided in the middle of the negative primary circuit 210b so as to be accommodated in the junction box 24.

[0061] The external relay 211 is replaceable. That is, the external relay 211 is provided detachably with respect to the junction box 24, and can be replaced in the event of a malfunction.

[0062] In the description of the electrical circuit 21, the "upstream side" means the side of the battery pack 22 (the side of the battery pack 22 from the reference point) based on any position on the electrical circuit connecting the battery pack 22 to the electrical device 20, and the "downstream side" means the side of the electrical device 20 (the side of the electrical device 20 from the reference point) based on any position on the electrical circuit connecting the battery pack 22 to the electrical device 20.

[0063] The electric work machine 1 according to this embodiment is as described above, and in executing the drive mode (start-up process), the control unit 23 supplies power to the electric devices 20 (inverter 20a, DC / DC converter 20b, heater 20c) in the following procedure, causing the electric devices 20 (inverter 20a, DC / DC converter 20b, heater 20c) to function. That is, among the multiple electric devices 20 (inverter 20a, DC / DC converter 20b, heater 20c), the inverter 20a, which is the electric device 20 that operates the work implements 11 (dozer implement 11a, shovel implement 11b), drives the electric motor 16 by receiving power, and the electric motor 16 operates the hydraulic pump 15.

[0064] Specifically, when the operator turns on the start switch to execute the drive mode (performs the start process), the control unit 23 (ECU 23a) judges whether or not the multiple battery packs 22 can be connected in parallel (parallel connection feasibility diagnosis). Specifically, as shown in FIG. 4, the BMS 23b measures the overall voltage of the battery packs 22 and sends the result to the ECU 23a (S1). The ECU 23a compares the voltages of the multiple battery packs 22 with each other and calculates the voltage difference between the battery packs 22, 22 in the combination to be compared (the two battery packs 22, 22) (S2). In this embodiment, since the electric work machine 1 includes only two battery packs 22, 22, the ECU 23a has only one combination to be compared and calculates the voltage difference between the two battery packs 22, 22.

[0065] The ECU 23a judges whether the calculated voltage difference coincides with a preset reference value (S3). The "reference value" here is a value that does not interfere with the flow of electricity between the battery packs 22, 22 due to a voltage difference between the battery packs 22, 22 when the battery packs 22, 22 are connected in parallel. In this embodiment, the "reference value" is set (stored in the ECU 23a) in a range between an upper threshold value and a lower threshold value (between the two threshold values), and is treated as a match if it is within the range of the two threshold values. Note that the reference value does not need to have a range (between the two threshold values) and may be a single threshold value.

[0066] 4 also assumes that there are three or more battery packs 22, and when there are three or more battery packs 22, there are three or more combinations to be compared. Accordingly, the ECU 23a calculates the voltage differences between the battery packs 22, 22 for the three or more combinations, and determines whether each voltage difference matches a reference value.

[0067] When it is determined that the voltage difference between the two battery packs 22, 22 that are the subject of comparison matches the reference value (YES in S3), the ECU 23a determines that the battery packs 22 of the compared combination (the two battery packs 22, 22) are to be connected in parallel (S4). That is, when there are three or more combinations to be compared, if it is determined that the voltage difference in each combination matches the reference value, all of the three or more battery packs 22 are determined to be connected in parallel (S4).

[0068] On the other hand, when it is determined that the voltage difference between the two battery packs 22, 22 to be compared does not match the reference value (NO in S3), the ECU 23a determines whether there is any other combination of the battery packs 22, 22 to be compared in which the voltage difference between the two battery packs 22, 22 matches the reference value (S5).When there is any other combination of the battery packs 22, 22 to be compared in which the voltage difference between the two battery packs 22, 22 matches the reference value (YES in S5), the ECU 23a determines the battery packs 22, 22 of the combination in which the voltage difference between the battery packs 22, 22 matches the reference value as the battery packs to be connected in parallel (S4).

[0069] If there is no other combination in which the voltage difference between the two battery packs 22, 22 in the other combinations to be compared matches the reference value (NO in S5), the ECU 23a determines to use the battery pack 22 with the higher voltage of the two battery packs 22, 22 to be compared as the power source (S6). That is, when the voltage difference between the battery packs 22, 22 to be compared exceeds the reference value (when the reference value has upper and lower thresholds, when it exceeds the upper threshold), the ECU 23a determines that the voltage difference between the battery packs 22, 22 is too large, and determines to connect the battery pack 22 with the highest voltage among the multiple battery packs 22 to the electric device 20 (S6).

[0070] In addition, when there are three or more combinations and none of the combinations match the reference value, the ECU 23a determines to use the battery pack 22 with the highest voltage among the three or more battery packs 22 as the power source (S6). In addition to this determination, the ECU 23a causes the monitor 142 in the cabin 14 to display a message indicating that "charging is required" to notify the operator to charge (S7, END).

[0071] As described above, in this embodiment, since only two battery packs 22, 22 are provided, if the voltage difference between the two battery packs 22, 22 matches the reference value (YES in S3), the ECU 23a determines that the two battery packs 22, 22 are to be connected in parallel (S4). On the other hand, if the voltage difference between the two battery packs 22, 22 does not match the reference value (NO in S3), the ECU 23a determines that there is no combination that can be connected in parallel (NO in S5), and determines that the battery pack 22 with the higher voltage of the two battery packs 22, 22 that are compared is to be used as the power source (S6). In conjunction with this determination, the ECU 23a displays a message on the monitor 142 in the cabin 14 that "charging is required" to notify the operator to charge (S7, END).

[0072] Through the above processing, the ECU 23a diagnoses whether or not multiple battery packs 22... can be connected in parallel. If, as a result, there is a combination of battery packs 22, 22 that can be connected in parallel, the ECU 23a performs processing to connect the battery packs 22... in parallel. If there is no combination of battery packs 22... that can be connected in parallel, the ECU 23a performs processing to connect a single battery pack 22 (single connection processing).

[0073] When performing parallel connection processing of the battery packs 22, as shown in FIG. 5, the ECU 23a checks the number of times the external relay 211 corresponding to the battery pack 22 that is the target of parallel connection (S10). That is, the ECU 23a cumulatively stores the number of times the external relay 211 corresponding to the battery pack 22 is opened and closed, and checks the current total number of times the external relay 211 is opened and closed at the time of startup (S10). Then, the ECU 23a determines the order of connecting the multiple battery packs 22 to the electric circuit 21 based on the number of times the external relay 211 is opened and closed (S11). In this embodiment, the ECU 23a sets the order of the battery packs 22 corresponding to the external relay 211 in descending order of the number of times the external relay 211 is opened and closed. That is, when the order of connecting the multiple battery packs 22 to the electric circuit 21 is determined (S11), the battery packs 22 connected to the external relay 211 that has the greatest number of times of opening and closing as the external relay 211 corresponding to the second battery pack 22 are assigned a smaller order (set in descending order from the first).

[0074] Although details will be described later, in this embodiment, the external relay 211 corresponding to the first battery pack 22 is not (is unlikely to be) damaged by the influence of inrush current accompanying opening and closing. On the other hand, the external relay 211 corresponding to the second battery pack 22 is damaged by the influence of inrush current during opening and closing, and damage accumulates (cumulates) according to the number of times of opening and closing.

[0075] Therefore, as the external relay 211 corresponding to the second battery pack 22, the connection of the battery pack 22 connected to the external relay 211 that is most damaged (the one that is opened and closed the most frequently) is By setting the order of the external relays 211 to be first, the influence (damage) of the inrush current on the external relay 211 that has been significantly damaged (has accumulated damage) is reduced, and the damage that each of the multiple external relays 211 receives is equalized.

[0076] Since the electric work machine 1 of this embodiment has only two battery packs 22, 22, when the machine is started for the first time, one of the battery packs 22 is set as the first battery pack (first battery pack) and the other battery pack 22 is set as the second battery pack or later (second battery pack), but when the machine is started for the second time or later, the battery pack 22 that is set as the first battery pack (set as the first battery pack) will alternate.

[0077] As described above, when the first battery pack 22 is determined, the ECU 23a executes a connection process of connecting the first battery pack (battery pack) 22 to the electric device 20. In this connection process, the ECU 23a executes a diagnosis process for the battery pack 22 designated as requiring a diagnosis process for the opening / closing operation of the internal relay 220, and omits the diagnosis process for the battery pack 22 designated as not requiring a diagnosis process for the opening / closing operation of the internal relay 220. In this embodiment, when the first battery pack 22 is determined, the ECU 23a executes a diagnosis process for the opening / closing operation of the internal relay 220 of the first battery pack 22 (S12). That is, the ECU 23a serving as the control unit 23 is configured to be set (designated) to perform diagnostic processing of the opening / closing operation of the internal relay 220 for the first battery pack 22, which is the first battery pack to be connected to the electric device 20 among the multiple battery packs 22, and to be able to designate whether or not diagnostic processing of the opening / closing operation of the internal relay 220 is required for the second battery pack 22, which is the second or subsequent battery pack to be connected to the electric device 20 among the multiple battery packs 22. In this embodiment, the ECU 23a serving as the control unit 23 is set (designated) to make diagnostic processing of the opening / closing operation of the internal relay 220 unnecessary (omitted) for the second battery pack 22.

[0078] Accordingly, as described above, when the first battery pack 22 is determined, the ECU 23a executes a diagnosis process for the opening and closing operation of the internal relay 220 (S12).

[0079] In a diagnostic process for the opening and closing operation of the internal relay 220, the ECU 23a, which is the control unit 23, determines whether the internal relay 220 is operable based on the opening and closing state of the internal relay 220 and the change in the state of the output voltage of the first battery pack 22 that accompanies switching between opening and closing of the internal relay 220.

[0080] In this embodiment, the battery pack 22 has a pre-charge relay 224b and a discharge relay 225b in addition to the internal relay 220 as relay switches, and therefore, in diagnosing the opening and closing operation of the relay switches, the ECU 23a determines whether or not each relay switch is malfunctioning based on the opening and closing states of the internal relays 220 (first internal relay 220a, second internal relay 220b), the pre-charge relay 224b, and the discharge relay 225b in the battery pack 22, and the change (presence or absence) in the output voltage of the battery pack 22 due to the opening and closing of the relay switches.

[0081] That is, in the diagnosis process of the internal relay 220, the ECU 23a, assuming that the relay switch in the battery pack 22 is an a-contact switch, identifies the relay switch that is malfunctioning (stuck) (internal relay 220 (first internal relay 220a, second internal relay 220b), pre-charge relay 224b) based on the combination of opening and closing of the relay switches in the battery pack 22 and the state of the output voltage of the battery pack 22 according to the opening and closing states of the relay switches (combination of opening and closing).

[0082] Specifically, the external relay 211, the internal relay 220 (first internal relay 220a Since the external relay 211, the internal relay 220 (first internal relay 220a, second internal relay 220b), the pre-charge relay 224b, and the discharge relay 225b are switches of contact a, they are normally in the open state, but in a diagnosis process for the opening and closing operation of the internal relay 220 etc., the ECU 23a instructs the external relay 211, the internal relay 220 (first internal relay 220a, second internal relay 220b), the pre-charge relay 224b, and the discharge relay 225b whether to open or close them.

[0083] Based on this instruction from ECU 23a, BMS 23b opens and closes the external relay 211, internal relay 220 (first internal relay 220a, second internal relay 220b), pre-charge relay 224b, and discharge relay 225b. However, here, a description of the instructions by ECU 23a and the execution by BMS 23b will be omitted, and an explanation will be given simply based on the open / closed states of the external relay 211, internal relay 220 (first internal relay 220a, second internal relay 220b), pre-charge relay 224b, and discharge relay 225b.

[0084] 6, first, the external relay 211 is closed, and the first internal relay 220a, the second internal relay 220b, the pre-charge relay 224b, and the discharge relay 225b are opened. In this state, if there is an output voltage of the battery pack 22 (there is a voltage rise), the ECU 23a determines that any one of the first internal relay 220a, the second internal relay 220b, and the pre-charge relay 224b is stuck in the closed state (first diagnosis).

[0085] From this state, the second internal relay 220b is closed, and in this state, if there is an output voltage of the battery pack 22 (there is a voltage increase), the ECU 23a determines that either the first internal relay 220a or the pre-charge relay 224b is stuck in the closed state (second diagnosis).

[0086] Then, the second internal relay 220b is opened and the pre-charge relay 224b is closed. In this state, if there is an output voltage of the battery pack 22 (there is a voltage increase), the ECU 23a determines that the second internal relay 220b is stuck in the closed state (third diagnosis).

[0087] Next, the second internal relay 220b is closed, and then the first internal relay 220a is closed. When the second internal relay 220b is closed, the output voltage of the battery pack 22 rises, and based on the raised output voltage, if the output voltage of the battery pack 22 does not rise (no voltage is generated) when the first internal relay 220a is closed, the ECU 23a determines that the second internal relay 220b or the pre-charge relay 224b is stuck in the open state, or that the discharge relay 225b is stuck in the closed state (fourth diagnosis).

[0088] Then, the pre-charge relay 224b is opened, and in this state, if the output voltage of the battery pack 22 does not increase (does not change) from the output power that was used as the reference in the fourth diagnosis, the ECU 23a determines that the first internal relay 220a is stuck in the open state (fifth diagnosis).

[0089] Furthermore, after the first internal relay 220a is set to the open state, the discharge relay 225b is set to the closed state. In this state, if the output voltage of the battery pack 22 does not drop from the output power that was used as the reference in the fourth diagnosis, the ECU 23a determines that the first internal relay 220a or the second internal relay 220b is stuck in the closed state, or that the discharge relay 225b is stuck in the open state (sixth diagnosis).

[0090] Next, the second internal relay 220b and the discharge relay 225b are opened, and if the output voltage of the battery pack 22 does not decrease at this time, the ECU 23a determines that the discharge relay 225b is stuck in the open state or the discharge resistor 225a has melted, or the first internal relay 220a or the second internal relay 220b is stuck in the closed state (seventh diagnosis).

[0091] In this way, the diagnostic process for the opening and closing operation of the relay switch (internal relay 220) can diagnose (determine) whether or not there is an abnormality in the relay switches 220, 224b, 225b (internal circuit 222) based on the state (change) of the voltage of the battery pack 22 that occurs when an abnormality occurs in multiple relay switches (internal relay 220 (first internal relay 220a, second internal relay 220b), pre-charge relay 224b, discharge relay 225b) within the battery pack 22.

[0092] In addition, the diagnostic process for the opening and closing operation in this embodiment is designed to find abnormalities in the relay switches based on a combination of the open and closed states of multiple relay switches (internal relays 220 (first internal relay 220a, second internal relay 220b), pre-charge relay 224b, and discharge relay 225b) in the battery pack 22 and the state of the output voltage of the battery pack 22 at the time of that combination, so that the relay switch having an abnormality can be identified from the multiple relay switches.

[0093] Then, as described above, a diagnosis process is performed on the opening and closing operation of the relay switches (internal relay 220 (first internal relay 220a, second internal relay 220b), pre-charge relay 224b, discharge relay 225b) of the first battery pack 22, and if it is determined that there is an abnormality in the relay switches (internal relay 220 (first internal relay 220a, second internal relay 220b), pre-charge relay 224b, discharge relay 225b), the drive mode (start-up process) is stopped, or a connection process of a single battery pack 22 (single connection process: see FIG. 8) is performed for the battery pack 22 as the second battery pack 22. Here, the drive mode (start-up process) is stopped, and accordingly, the fact that there is an abnormality in the battery pack 22 is displayed on the notification means (monitor) 142 to notify the operator.

[0094] Returning to FIG. 5, as described above, the ECU 23a performs diagnostic processing of the opening and closing operation of the relay switches (internal relay 220 (first internal relay 220a, second internal relay 220b), pre-charge relay 224b, and discharge relay 225b) of the first battery pack 22, and when it is determined that there is no abnormality in the relay switches (internal relay 220 (first internal relay 220a, second internal relay 220b), pre-charge relay 224b, and discharge relay 225b), the ECU 23a changes the external relay 211 corresponding to the first battery pack 22 from an open state to a closed state (S13: first pre-stage processing (second connection processing)). That is, the ECU 23a changes the external relay 211 on the primary circuit 210 connected to the first battery pack 22 from an open state to a closed state (S13: first pre-stage processing (second connection processing)). In this embodiment, the ECU 23a changes the external relay 211 on the negative electrode primary circuit 210b connected to the first battery pack 22 from an open state to a closed state (S13: first pre-stage processing (second connection processing)).

[0095] The ECU 23a waits until the external relay 211 of the primary circuit 210 (negative primary circuit 210b) connected to the first battery pack 22 is closed (S14). When the external relay 211 on the primary circuit 210 (negative primary circuit 210b) is closed (YES in S14), the ECU 23a instructs the pre-charge relay 224b of the first battery pack 22 to be switched from the open state to the closed state (S15: second pre-stage processing). In addition, the ECU 23a instructs the internal relay 220 of the first battery pack 22 to be closed in conjunction with closing the pre-charge relay 224b (S15: third pre-stage processing (first connection processing)). In response to this, the BMS 23b corresponding to the first set battery pack 22 closes the internal relay 220 and the pre-charge relay 224b (S15: second pre-stage processing, third pre-stage processing).

[0096] In this embodiment, the battery pack 22 includes a first internal relay as the internal relay 220. Since the precharge circuit 224 is connected in parallel with the first internal relay 220a, when the BMS 23b changes the internal relay 220 of the first battery pack 22 from an open state to a closed state, the BMS 23b changes the first internal relay 220a, which is in parallel with the precharge relay 224b, from an open state to a closed state after changing the second internal relay 220b and the precharge relay 224b from an open state to a closed state (after the precharge in the precharge circuit 224 is completed) (S15: third pre-stage processing). That is, the first internal relay 220a connected in parallel with the precharge circuit 224 finally changes to a closed state, so that the entire internal circuit 222 is in a closed state (conductive state), and the first battery pack 22 is electrically connected to the electric circuit 21 (electrical device 20) (S15: third pre-stage processing).

[0097] An inrush current (starting current) that would normally act on the first internal relay 220a when the first internal relay 220a is closed passes through the precharge circuit 224 connected in parallel to the first internal relay 220a, and is absorbed by the precharge resistor 224a on the precharge circuit 224. This prevents the internal relay 220 (220a, 220b) of the first battery pack 22 from being damaged by the influence of the inrush current.

[0098] The ECU 23a waits until the internal relays 220 (the first internal relay 220a and the second internal relay 220b) of the first battery pack 22 are closed (S16). Although not shown in the flow diagram of Fig. 5, when precharging is performed in the precharge circuit 224, once the internal circuit 222 is closed after the precharge is completed, the first internal relay 220a in parallel with the precharge relay 224b ensures continuity of the internal circuit 222, so that the precharge relay 224b is opened when the first internal relay 220a is closed.

[0099] Then, when the entire internal circuit 222 of the first battery pack 22 is in a conductive state (the internal relays 220 (the first internal relay 220a and the second internal relay 220b) are in a closed state) (YES in S16), the ECU 23a extracts a battery pack 22 that is to be next connected (the battery pack to be connected) from among the battery packs 22 set second or later (S17). In this embodiment, the ECU 23a extracts the other battery pack 22 as the next battery pack to be connected (S17).

[0100] When the ECU 23a extracts the second battery pack 22 (S17), it instructs whether or not to perform a fault diagnosis (external relay diagnosis process, open / close relay diagnosis process) on the discharge relay 225b of the second battery pack 22 (the second or subsequent battery pack 22 to be connected) and the external relay 211 of the electric circuit 21. That is, if it is set to perform a fault diagnosis (YES in S18), the ECU 23a performs a fault diagnosis (S24), and if it is set to not perform a fault diagnosis (NO in S18), it proceeds to the next step (S19) without performing a fault diagnosis.

[0101] In this embodiment, as described above, the diagnostic process for the opening and closing operation of the internal relay 220 of the battery pack 22 is set to be performed for the first battery pack 22 and omitted (not executed) for the second battery pack 22, and therefore a determination as to whether or not the diagnostic process for the opening and closing operation of the internal relay 220 for the second battery pack 22 is required (presence or absence) is omitted. Note that, in the diagnostic process for the opening and closing operation of the internal relay 220 of the battery pack 22, in addition to the diagnosis of the internal relays 220 (first internal relay 220a, second internal relay 220b), the diagnosis of the opening and closing operation of the discharge relay 225b is included, but the fault diagnosis (opening and closing relay diagnostic process) here is specialized for the discharge relay 225b.

[0102] Regarding the specification of whether or not a fault diagnosis is performed for the discharge relay 225b and the external relay 211, preset contents are stored in the storage unit of the ECU 23a. a follows the contents stored in the memory unit.

[0103] In this embodiment, the fault diagnosis (external relay diagnostic processing, open / close relay diagnostic processing) is specified to be performed. Accordingly, the ECU 23a performs the fault diagnosis (external relay diagnostic processing, open / close relay diagnostic processing) (YES in S18, S24). As shown in FIG. 7, when the ECU 23a performs the fault diagnosis (external relay diagnostic processing, open / close relay diagnostic processing), the ECU 23a first monitors (measures) the external terminals (positive output terminal 223a, negative output terminal 223b) of the second battery pack 22 and the voltage of the discharge circuit 225 (the voltage across the discharge circuit 225) (S30). Since the discharge circuit 225 is inside the battery pack 22, the BMS 23b monitors (measures) the voltage of the discharge circuit 225 (the voltage across the discharge circuit 225) and transmits the monitoring (measurement) result to the ECU 23a.

[0104] Based on this, the ECU 23a judges whether or not there is a voltage at the external terminals (positive output terminal 223a, negative output terminal 223b) of the battery pack 22 (S31). If the voltage at the external terminals (positive output terminal 223a, negative output terminal 223b) is equal to or higher than the threshold (YES in S31), the ECU 23a judges that the external relay 211 on the primary circuit 210 is connected (fixedly connected by welding) and that there is an abnormality in the external relay 211 in the electric system of the battery pack 22 to be connected (S37). On the other hand, if the voltage at the external terminals (positive output terminal 223a, negative output terminal 223b) is lower than the threshold (NO in S31), the ECU 23a changes the external relay 211 on the primary circuit 210 from an open state to a closed state (S32). The threshold used as a reference for this judgment is set to a power supply voltage value in the specifications of the battery pack 22.

[0105] In this state, the ECU 23a judges whether or not there is a voltage across the external terminals (positive output terminal 223a, negative output terminal 223b) and both ends of the discharge circuit 225 (S33, S34). As a result, if the voltage across the external terminals (positive output terminal 223a, negative output terminal 223b) is not equal to or higher than the threshold (NO in S33), the ECU 23a judges that the external relay 211 on the primary circuit 210 has failed (has not changed from an open state to a closed state) (S37).

[0106] On the other hand, if the voltage at the external terminals (positive output terminal 223a, negative output terminal 223b) is equal to or higher than the threshold value (YES in S33), it can be assumed that the external relay 211 on the primary circuit 210 has properly changed from an open state to a closed state, and therefore the ECU 23a determines whether or not there is a voltage across the discharge circuit 225 (S34). Here, the voltage across the discharge circuit 225 refers to the voltage on both sides of the discharge relay 225b (one side and the other side sandwiching the discharge relay 225b).

[0107] If there is a voltage across the discharge circuit 225 and the voltage is equal to or lower than the threshold (NO in S34), the ECU 23a determines that the discharge relay 225b is faulty (not open) (S38). On the other hand, if the voltage of the discharge circuit 225 is higher than the threshold (YES in S34), the ECU 23a determines that the discharge relay 225b on the discharge circuit 225 is open and that the connected battery pack 22 and its electrical system (the discharge relay 225b and the external relay 211) are normal (S35).

[0108] Here, the voltage across the discharge circuit 225 when the discharge relay 225b is in the open state is larger (higher) than the voltage across the discharge circuit 225 when the discharge relay 225b is in the closed state because the state of the potential on both sides of the discharge relay 225b changes depending on the open / close state of the discharge relay 225b. Specifically, when the discharge relay 225b is in the closed state, a current flows from the positive side to the negative side, and there is no difference (potential difference) between the potential on the positive side and the potential on the negative side (it becomes zero). On the other hand, when the discharge relay 225b is in the open state, there is a potential on the positive side, but the potential on the negative side is zero because the negative side is grounded.

[0109] This generates a difference (potential difference) between the potential on the positive electrode side and the potential on the negative electrode side on both sides of the discharge relay 225b. Therefore, the voltage (potential difference) across the discharge circuit 225 when the discharge relay 225b is in the open state is larger (higher) than the voltage (potential difference) across the discharge circuit 225 when the discharge relay 225b is in the closed state.

[0110] If the ECU 23a determines that the discharge relay 225b is normal (S35), it returns the external relay 211 to the open state (S36) and ends the diagnosis (END).

[0111] Returning to FIG. 5, when the ECU 23a determines as a result of the failure diagnosis that there is an abnormality in the second battery pack 22 and the external relay 211 (YES in S25), it determines whether there is another second battery pack 22 (S23). If there is no other second battery pack 22 (YES in S23), it does not connect the second battery pack 22 determined to be abnormal (does not connect the subsequent battery pack 22 in the order), and ends the battery parallel connection process (END). That is, the ECU 23a instructs that power is to be supplied only by the first battery pack 22. On the other hand, when there is another second battery pack 22 (YES in S23), the ECU 23a extracts (determines) the battery pack 22 to be connected next to the electric device 20 from the other second battery packs 22 (S17), and determines whether a failure diagnosis is necessary in the same manner as for the previous second battery pack 22 (S18 to S25).

[0112] When it is determined that there is no abnormality (normal) in the second battery pack 22 and the external relay 211 (NO in S25), the ECU 23a executes a connection process of connecting the second battery pack (battery pack) to the electric device 20. In this connection process, similarly to the first battery pack 22, the ECU 23a performs diagnostic processing for the battery pack 22 designated as requiring diagnostic processing of the opening / closing operation of the internal relay 220, and omits diagnostic processing for the battery pack 22 designated as not requiring diagnostic processing of the opening / closing operation of the internal relay 220. In this embodiment, for the second battery pack (battery pack), it is designated as not requiring diagnostic processing of the opening / closing operation of the internal relay 220, and accordingly, diagnostic processing is omitted for the second battery pack 22.

[0113] Specifically, in this embodiment, the ECU 23a, based on the instruction stored in the storage unit, eliminates the need to diagnose the opening and closing operation of the internal relay 220 of the second battery pack 22 and eliminates the need to perform precharging by the precharge circuit 224, and issues an instruction to change the internal relay 220 of the battery pack 22 to be connected from an open state to a closed state (S19: first post-stage processing (first connection processing)). That is, unlike the connection order of the first battery pack 22, the ECU 23a issues an instruction to change the internal relay 220 of the second battery pack 22 from an open state to a closed state without using the precharge circuit 224 (S19: first post-stage processing (first connection processing)). Accordingly, the BMS 23b changes the internal relay 220 from an open state to a closed state (S19: first post-stage processing (first connection processing)).

[0114] In this embodiment, the ECU 23a closes the first internal relay 220a and the second internal relay 220b simultaneously based on the instruction stored in the storage unit (S19: first subsequent stage processing). Specifically, the battery pack 22 includes the first internal relay 220a and the second internal relay 220b as the internal relays 220, but the ECU 23a issues an instruction for the second battery pack 22 to simultaneously change the first internal relay 220a and the second internal relay 220b from the open state to the closed state based on the instruction stored in the storage unit without giving priority to the first internal relay 220a and the second internal relay 220b (S19: first subsequent stage processing (first connection processing)). Accordingly, the BMS 23b changes the first internal relay 220a and the second internal relay 220b simultaneously from the open state to the closed state (S19: first subsequent stage processing (first connection processing)).

[0115] The ECU 23a waits for the internal relay 220 (first internal relay 220a, second internal relay 220b) to change from an open state to a closed state (S20), and when the internal relay 220 (first internal relay 220a, second internal relay 220b) changes from an open state to a closed state (YES in S20), changes the external relay 211 corresponding to the second battery pack 22 (the external relay 211 on the primary circuit 210 connected to the battery pack 22) from an open state to a closed state (S21: second post-stage processing (second post-stage processing)).

[0116] Then, when the external relay 211 corresponding to the second battery pack 22 is closed (YES in S22), the ECU 23a checks whether or not there is a subsequent battery pack 22 (a second battery pack 22 to be connected as a remaining connection target) (S23), and if it determines that there is a subsequent battery pack 22 (NO in S23), it extracts the next battery pack 22 in order and repeats the above procedure (S17 to S23).

[0117] On the other hand, if it is determined that there is no succeeding battery pack 22 (YES in S23), all of the multiple battery packs 22, 22 that are the subject of parallel connection are connected to the electric circuit 21 and supply power to the electric device 20.

[0118] Here, with regard to the second battery pack 22, the internal relay 220 is changed from an open state to a closed state, and then the external relay 211 on the primary circuit 210 is changed from an open state to a closed state, so that a starting current or a current flowing in due to a voltage difference with the previously connected battery pack 22 acts as an inrush current on the external relay 211, but damage to the internal relay 220 of the battery pack 22 can be avoided. Also, unlike the internal relay 220 of the battery pack 22, the external relay 211 that is replaceably mounted inside the junction box 24 is damaged by the inrush current, so even if the external relay 211 is damaged, it can be easily restored by replacement.

[0119] The parallel connection process of the multiple battery packs 22 is as described above, and when the ECU 23a determines not to connect the multiple battery packs 22 in parallel in the parallel connection feasibility diagnosis (when the battery pack 22 with the larger remaining charge is determined to be the power source), the ECU 23a performs a single connection process of the battery packs 22. Specifically, as shown in Fig. 8, the ECU 23a changes the external relay 211 on the primary circuit 210 (210b) connected to the first battery pack 22 from an open state to a closed state (S40). The ECU 23a changes the external relay 211 on the negative electrode primary circuit 210b connected to the first battery pack 22 from an open state to a closed state.

[0120] The ECU 23a waits until the external relay 211 of the primary circuit 210 (negative primary circuit 210b) connected to the first battery pack 22 is closed (S41), and when the external relay 211 on the primary circuit 210 (negative primary circuit 210b) is closed (YES in S41), the ECU 23a issues an instruction to close the pre-charge relay 224b and the internal relay 220 of the first battery pack 22 (S42). Accordingly, the BMS 23b corresponding to the first set battery pack 22 closes the pre-charge relay 224b and the internal relay 220 (S42).

[0121] Specifically, the ECU 23a instructs the pre-charge relay 224b of the first battery pack 22 to be switched from an open state to a closed state (second pre-stage processing). In addition, the ECU 23a instructs the internal relay 220 of the first battery pack 22 to be closed (third pre-stage processing). In response to this, the BMS 23b corresponding to the first battery pack 22 closes the internal relay 220 and the pre-charge relay 224b (second pre-stage processing, third pre-stage processing).

[0122] In this embodiment, the battery pack 22 includes a first internal relay 220a and a second internal relay 220b as the internal relay 220, and the precharge circuit 224 is connected in parallel with the first internal relay 220a. Therefore, when the BMS 23b changes the internal relay 220 of the first battery pack 22 from an open state to a closed state, the BMS 23b changes the second internal relay 220b and the precharge relay 224b from an open state to a closed state (after precharge in the precharge circuit 224 is completed), and then changes the first internal relay 220a, which is in parallel with the precharge relay 224b, from an open state to a closed state (third pre-stage processing).

[0123] In this way, the first internal relay 220a connected in parallel to the precharge circuit 224 finally becomes closed, so that the entire internal circuit 222 becomes closed (conductive), and the first battery pack 22 is electrically connected to the electric circuit 21 (electrical device 20) (third pre-stage processing).

[0124] Normally, when the first internal relay 220a is finally closed, the inrush current (starting current) acting on the first internal relay 220a passes through the precharge circuit 224 connected in parallel to the first internal relay 220a, and is absorbed by the precharge resistor 224a on the precharge circuit 224. Therefore, the internal relay 220 (220a, 220b) of the first battery pack 22 is prevented from being damaged by the influence of the inrush current.

[0125] Then, the ECU 23a waits until the internal relay 220 (the first internal relay 220a and the second internal relay 220b) of the first battery pack 22 is closed (S43). When the internal relay 220 (the first internal relay 220a and the second internal relay 220b) of the first battery pack 22 is closed (YES in S43), the ECU 23a ends the single connection process of the battery packs 22, and the battery pack 22 with the highest voltage is connected to the electric device 20 to drive the electric device 20. Although not shown in the flow chart of FIG. 8, when the battery pack 22 is connected to the electric device 20, the ECU 23a instructs the precharge relay 224b of the precharge circuit 224 of the first battery pack 22 to be changed from a closed state to an open state. Accordingly, the BMS 23b changes the precharge relay 224b of the precharge circuit 224 of the first battery pack 22 from a closed state to an open state.

[0126] In the above parallel connection possibility diagnosis, a notice is given that charging is necessary. In response to this notice, when the operator charges the battery pack 22, a charging cable connected to a charging device (for example, a quick charger) is connected to the charging inlet 25.

[0127] When a charging cable is connected to the charging inlet 25, the ECU 23a detects the connection and executes a charging mode in which the battery pack 22 is charged.

[0128] 9, in the charging mode, the ECU 23a sets the battery pack 22 with the lowest voltage as the battery pack to be charged (S50). In this embodiment, the battery pack 22 that was not selected as the battery pack to be connected to the electric circuit 21 in the previous parallel connection feasibility diagnosis is set as the battery pack to be charged (S50). That is, the ECU 23a sets the battery pack 22 with the least remaining charge among the multiple battery packs 22 as the battery pack to be charged.

[0129] In response to this, the ECU 23a changes the external relay 211 on the primary circuit 210 (210b) connected to the battery pack 22 to be charged from an open state to a closed state, and changes the external relay 211 connected to the battery pack 22 not to be charged (the battery pack 22 with a large remaining capacity) from an open state to a closed state. This causes an external relay 211 on the primary circuit 210 (210b) to be maintained in an open state.

[0130] As a result, while the electrical connection between the battery pack 22 with a large remaining capacity and the charging inlet 25 is cut off, the charging inlet 25 and the battery pack 22 with a small remaining capacity are electrically connected to each other.

[0131] When charging of a battery pack 22 with a low voltage (a battery pack 22 with a low remaining capacity) is started (YES in S51), the ECU 23a measures the voltage of each of the multiple battery packs (all battery packs) 22... including the battery pack 22 that is not the target of charging (S52). Based on this, the ECU 23a compares the voltages of each of the multiple battery packs 22... with each other (S53). That is, the ECU 23a calculates the voltage difference between the battery packs 22 (two battery packs 22, 22) in the combination to be compared (S53). In this embodiment, since the electric work machine 1 has only two battery packs 22, 22, there is only one combination to be compared, and the ECU 23a calculates the voltage difference between the two battery packs 22, 22 (S53).

[0132] The ECU 23a compares the voltages of the battery packs 22 and determines whether the voltage of the battery pack 22 being charged has become equivalent to the voltage of a battery pack 22 not being charged (the battery pack 22 with a higher voltage) (the voltage difference is approximately zero: reference value with the battery pack 22 with a higher voltage as a reference) (S54). In this embodiment, based on the calculation of the voltage difference in S53, which is the voltage comparison, when the voltage difference of the battery pack 22 being compared becomes zero or approximately zero, the ECU 23a determines that the voltage of the battery pack 22 being charged has become equivalent to the voltage of the battery pack 22 not being charged (YES in S54).

[0133] When the ECU 23a determines that the voltage of the battery pack 22 being charged has become equivalent to the voltage of a battery pack 22 that is not being charged (YES in S54), it changes the external relay 211 on the primary circuit 210 connected to the battery pack 22 that is not being charged (the battery pack 22 with a large remaining charge) from an open state to a closed state (S55). That is, in a state where the voltages of the battery packs 22, 22 that are the subject of comparison are the same or approximately the same, all the battery packs 22 that are the subject of comparison are connected in parallel and charged until they are fully charged (S55).

[0134] As a result, each of the battery packs 22 is charged to full charge while the voltage difference is at the reference value (when there is no voltage difference between the battery packs 22 or the voltage difference is small) (S56). If there are three or more battery packs 22, the battery packs 22 that have not been charged are charged in order, provided that their voltages match or nearly match.

[0135] In this way, at start-up, there is no voltage difference or the voltage difference is small among the multiple battery packs 22..., so that when the battery packs 22 are connected in parallel, damage to the external relay 211 that is closed last can be reduced. Also, since the multiple battery packs 22... are fully charged, long-term operation is possible.

[0136] In this embodiment, when the electric work machine 1 is stopped, the start switch is turned OFF, and the ECU 23a switches the internal relay 220 of the battery pack 22 and the external relay 211 on the primary circuit 210 from a closed state to an open state, thereby disconnecting the electrical system and cutting off the power supply from the battery pack 22 to the electrical equipment 20.

[0137] The electric operating machine 1 according to this embodiment is as described above. The electric operating machine 1 includes a plurality of inventions (a group of inventions), each of which provides unique actions and effects.

[0138] Specifically, in the above embodiment, the electric operating machine 1 includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, and a plurality of battery packs 22... each having an internal relay 220 that opens and closes an internal circuit 222, the plurality of battery packs 22... being sequentially connected to the electric device 20 via the electric circuit 21 and connected in parallel, and a control unit 23. The electric circuit 21 includes a plurality of external relays 211... corresponding to the plurality of battery packs 22..., each of which opens and closes a circuit connecting the corresponding battery pack 22 and the electric device 20. The control unit 23 electrically connects, to the electrical device 20, a first battery pack 22 which is the first battery pack 22 to be connected to the electrical device 20 among the plurality of battery packs 22..., and performs a first post-stage process (S19) of closing the internal relay 220 of a second battery pack 22 which is the second or subsequent battery pack 22 among the plurality of battery packs 22..., and a second post-stage process (S21) of closing the external relay 211 corresponding to the second battery pack 22 whose internal relay 220 has been closed.

[0139] According to the above configuration, the electrical circuit 21 includes a plurality of external relays 211... corresponding to each of the plurality of battery packs 22... and opening and closing the circuit connecting the corresponding battery packs 22 and the electrical device 20. Therefore, when the plurality of external relays 211... are closed in sequence, the plurality of battery packs 22... are connected in sequence to the electrical device 20 (electrical circuit 21), and when all of the plurality of external relays 211 are closed, the plurality of battery packs 22... are connected in parallel to the electrical device 20 (electrical circuit 21).

[0140] Since each of the battery packs 22 has an internal relay 220, when the internal relay 220 is open, the internal circuit 222 is open, but when the internal relay 220 is closed, the internal circuit 222 is also closed. Therefore, as described above, when the internal relays 220 of the battery packs 22 are closed and all of the external relays 211 are closed, the battery packs 22 are electrically connected in parallel to the electric device 20. This reduces the electrical load per battery pack 22, making it possible to suppress the occurrence of power supply troubles (breakdowns) in the electric work machine 1.

[0141] In the above configuration, the multiple battery packs 22 are sequentially connected to the electric device 20. Here, the first battery pack 22 is electrically connected to the electric device 20 by closing the internal relay 220 and closing the external relay 211 corresponding to the battery pack 22.

[0142] Based on this state, the control unit 23 performs a first post-processing (S19) of closing the internal relay 220 of the second battery pack 22, and a second post-processing (S21) of closing the external relay 211 corresponding to the second battery pack 22 whose internal relay 220 has been closed, thereby connecting the battery pack 22 to the electrical device 20 without an inrush current acting on the internal relay 220 of the battery pack 22.

[0143] That is, after the internal relay 220 of the battery pack 22 is closed in the first post-stage process (S19), when the external relay 211 is closed in the second post-stage process (S21), an inrush current acts on the external relay 211 that was last closed. That is, the external relay 211 outside the battery pack 22 receives the inrush current.

[0144] Therefore, according to the electric working machine 1 of the above embodiment, even if a plurality of battery packs 22 are connected in parallel, it is possible to prevent the battery packs 22 from breaking down due to the influence of the inrush current when the electric device 20 is started.

[0145] Furthermore, at least the first battery pack 22 has a first internal relay 220a as the internal relay 220, and a precharge circuit 224 in which a series-connected circuit of a precharge resistor 224a and a precharge relay 224b is connected in parallel to the first internal relay 220a, and when the control unit 23 connects the first battery pack 22 to the electrical device 20, it performs a first pre-stage process of closing the external relay 211 corresponding to the first battery pack 22, a second pre-stage process of closing the precharge relay 224b of the first battery pack 22, and a third pre-stage process of closing the first internal relay 220a of the first battery pack 22 after the first pre-stage process and the second pre-stage process.

[0146] In this way, when the external relay 211 is closed in the first pre-stage process (S13), the electric circuit 21 is closed (conductive), but in this state, since the internal circuit 222 of the battery pack 22 is open, no inrush current acts on the external relay 211. Also, in the second pre-stage process (S15), the pre-charge relay 224b of the pre-charge circuit 224 is closed, so that the pre-charge circuit 224 connects the circuit across the internal relay 220.

[0147] Accordingly, the first pre-stage process (S13) is performed before or after the second pre-stage process (S15), and the external relay 211 corresponding to the first battery pack 22 is closed, thereby causing the internal circuit 222 and the electric circuit 21 of the battery pack 22 to be in a conductive state. As a result, an inrush current occurs due to the power supply from the single battery pack 22, but since the pre-charge circuit 224 is in a closed state and in a state in which pre-charge is being performed (the pre-charge resistor 224a of the pre-charge circuit 224 absorbs the inrush current), damage to the internal circuit 222 and the electric circuit 21 (external relay 211) is reduced.

[0148] Then, in the third pre-stage processing (S15), the internal relay 220 (first internal relay 220a) in parallel with the pre-charge circuit 224 of the first battery pack 22 is closed, thereby making it possible to achieve a circuit configuration that does not impose a load on the pre-charge resistor 224a of the pre-charge circuit 224 (normal circuit configuration when current is applied).

[0149] Each of the multiple battery packs 22... has a battery cell 221 and, as internal relays 220, a first internal relay 220a arranged on a path 222a on one pole side of the battery cell 221 and arranged in parallel with the pre-charge circuit 224, and a second internal relay 220b arranged on a path 222b on the other pole side of the battery cell 221, and in the second pre-stage processing, the control unit 23 maintains the first internal relay 220a in an open state and closes the second internal relay 220b and the pre-charge relay 224b.

[0150] In this way, when the second internal relay 220b and the pre-charge relay 224b are closed in the second pre-stage process, the internal circuit 222 is brought into a conductive state via the pre-charge circuit 224, but since the pre-charge circuit 224 has the pre-charge resistor 224a, power is consumed by the pre-charge resistor 224a. As a result, even if the first internal relay 220a is closed in the third pre-stage process (S15), the inrush power acting on the first internal relay 220a is small, and shocks acting on the first internal relay 220a are reduced.

[0151] In the above embodiment, the electric operating machine 1 further includes a junction box 24 that houses a part or all of the electric circuit 21, and the multiple external relays 211 are replaceably housed within the junction box 24. In this manner, even if the external relay 211 breaks down, it is possible to easily restore the operation by replacing the broken external relay 211 with a new external relay 211.

[0152] In the above embodiment, the electric work machine 1 further includes a working device 11 that performs a predetermined task, and the electric device 20 directly or indirectly drives the working device 11. In this manner, the electric device 20 drives the working device 11 by receiving power supply from the battery pack 22 having an undamaged internal circuit 222 (such as the internal relay 220). In other words, the battery pack 22 is connected to the electric device 20 via the above startup process, thereby preventing the internal relay 220 from being damaged or sustaining damage during the startup process, and thus preventing a power supply failure from occurring when the electric device 20 drives the working device 11.

[0153] The control unit 23 sets the battery pack 22 corresponding to the external relay 211 with the largest cumulative number of opening and closing counts among the plurality of external relays 211 as the first battery pack 22. In this way, damage received by each of the plurality of external relays 211 can be equalized.

[0154] Specifically, the damage to the external relay 211 varies depending on the number of opening and closing. That is, the more the number of opening and closing, the more the external relay 211 is damaged by opening and closing the circuit, whereas the less the number of opening and closing, the less the damage is caused by opening and closing the circuit. In the above embodiment, the external relay 211 corresponding to the first battery pack 22 connected to the electric device 20 is closed first in the entire electric system including the battery pack 22, and is therefore not affected (hardly affected) by the inrush current. On the other hand, the external relay 211 corresponding to the second battery pack 22 connected to the electric device 20 is closed last in the entire electric system, and is therefore affected by the inrush current and is heavily damaged. In particular, the damage to the external relay 211 corresponding to the battery pack 22 that is set to the second battery pack 22 many times (set to be connected second or later) accumulates and becomes large.

[0155] However, in the above embodiment, the battery pack 22 corresponding to the external relay 211 with the highest cumulative number of opening and closing times is set to be first in the order (set as the first battery pack 22), so that the damage to the external relay 211 that has been severely damaged is reduced. And, every time the electric device 20 is started, the first battery pack 22 connected to the electric device 20 (electric circuit 21) is changed, and the external relay 211 that is first closed is also changed, so that the damage received by each of the multiple external relays 211 can be equalized. This makes it possible to prevent a specific external relay 211 from breaking down.

[0156] In the above embodiment, the method for starting the electric work machine 1 includes: an electric device 20; an electric circuit 21 electrically connected to the electric device 20; and a plurality of battery packs 22... each having an internal relay 220 for opening and closing an internal circuit 222, the plurality of battery packs 22... being sequentially connected to the electric device 20 via the electric circuit 21 and connected in parallel, the electric circuit 21 including a plurality of external relays 211... corresponding to each of the plurality of battery packs 22... and a plurality of external relays 211... for opening and closing a circuit connecting the corresponding battery pack 22 and the electric device 20. In a method for starting an electric work machine 1 including internal relays 211..., a first battery pack 22, which is the first battery pack 22 to be connected to an electric device 20 among a plurality of battery packs 22..., is electrically connected to the electric device 20, and a first subsequent process is performed to close the internal relay 220 of a second battery pack 22, which is the second or subsequent battery pack 22 among the plurality of battery packs 22..., and a second subsequent process is performed to close the external relay 211 corresponding to the second battery pack 22 whose internal relay 220 has been closed.

[0157] In the above startup method, a first post-stage process (S19) is performed to close the internal relay 220 of the second battery pack 22, and a second post-stage process (S21) is performed to close the external relay 211 corresponding to the second battery pack 22 whose internal relay 220 has been closed. The battery pack 22 is connected to the electric device 20 without an inrush current acting on the internal relay 220 of the battery pack 22.

[0158] That is, after the internal relay 220 of the battery pack 22 is closed in the first post-stage process (S19), when the external relay 211 is closed in the second post-stage process (S21), an inrush current acts on the external relay 211 that was last closed. That is, the external relay 211 outside the battery pack 22 receives the inrush current.

[0159] Therefore, according to the above-described method for starting the electric working machine 1, even if a plurality of battery packs 22 are connected in parallel, it is possible to prevent the battery packs 22 from breaking down due to the influence of an inrush current when the electric device 20 is started.

[0160] In the above embodiment, the electric work machine 1 includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, and a plurality of battery packs 22... each having an internal relay 220 that opens and closes an internal circuit 222, the plurality of battery packs 22... being sequentially connected to the electric device 20 via the electric circuit 21 and connected in parallel, and a control unit 23, the electric circuit 21 including a plurality of external relays 211... corresponding to each of the plurality of battery packs 22... and opening and closing a circuit connecting the corresponding battery pack 22 and the electric device 20, the control unit 23 being configured to be able to specify for each battery pack 22 whether or not diagnostic processing of the opening and closing operation of the internal relay 220 of the battery pack 22 is required, and when the battery pack 22 is connected to the electric device 20, diagnostic processing is performed for the battery packs 22 designated as requiring diagnostic processing of the opening and closing operation, and diagnostic processing is omitted for the battery packs 22 designated as not requiring diagnostic processing of the opening and closing operation.

[0161] According to the above configuration, for the battery pack 22 designated as requiring diagnostic processing of the opening and closing operation, diagnostic processing is performed, so that power can be supplied to the electrical device 20 even when there is no internal trouble in the battery pack 22 (such as trouble in the internal relay 220).

[0162] In contrast, for the battery pack 22 for which the diagnosis process for the opening and closing operation is specified as not being required, the diagnosis process is omitted, so that the connection time of the battery pack 22 to the electric device 20 can be shortened.

[0163] The control unit 23 specifies that diagnostic processing should be performed on the first battery pack 22, which is the first battery pack 22 to be connected to the electrical device 20 among the multiple battery packs 22, and specifies that diagnostic processing should be omitted on the second battery pack 22, which is the second or subsequent battery pack 22 to be connected to the electrical device 20 among the multiple battery packs 22.

[0164] In this manner, the control unit 23 specifies that diagnostic processing should be omitted for the second and subsequent battery packs 22 among the multiple battery packs 22, and thus the connection time of the battery packs 22 can be shortened by omitting the diagnostic processing depending on the situation.

[0165] The control unit 23 diagnoses the opening and closing operation of the internal relay 220 based on the state of the opening / closing instruction for the internal relay 220 and the change in the output voltage of the battery pack 22 accompanying the opening / closing instruction for the internal relay 220. In this way, it is possible to identify not only the presence or absence of a problem with the internal relay 220, but also the internal relay 220 that is in trouble.

[0166] On the premise of the above processing, each of the plurality of battery packs 22... has a precharge circuit 224 that connects a series-connected circuit of a precharge resistor 224a and a precharge relay 224b to an internal relay 220 in parallel, and the control unit 23 closes the internal relay 220. The system is configured such that whether or not to perform pre-charging, in which the pre-charging relay 224b is closed before the battery pack 22 is turned on, can be specified for each battery pack 22, and when a battery pack 22 designated as requiring pre-charging is connected to an electric device 20, a first connection process (third pre-stage process) S15 is performed in which the internal relay 220 of the battery pack 22 is closed after pre-charging, and when a battery pack 22 designated as not requiring pre-charging is connected to an electric device 20, a first connection process (first post-stage process) S19 is performed without performing pre-charging.

[0167] In this manner, when connecting a battery pack 22 that is specified as requiring precharging to an electric device 20, the first connection process (third pre-stage process) S15 is performed after precharging, so that the battery pack 22 can be connected to the electric device 20 without any internal trouble (such as trouble caused by the influence of inrush current on the internal relay 220).

[0168] In contrast, when a battery pack 22 for which pre-charging is specified as not being required is connected to an electric device 20, pre-charging is omitted, so that the connection time of the battery pack 22 to the electric device 20 can be shortened.

[0169] In the above embodiment, the electric operating machine 1 includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, a plurality of battery packs 22... each having an internal relay 220 that opens and closes an internal circuit 222, the plurality of battery packs 22... being sequentially connected to the electric device 20 via the electric circuit 21 and connected in parallel, and a control unit 23, the electric circuit 21 including a plurality of external relays 211... corresponding to the plurality of battery packs 22... respectively, the plurality of external relays 211... opening and closing a circuit connecting the corresponding battery pack 22 and the electric device 20, and each of the plurality of battery packs 22... is connected to the internal relay 220 via a pre-charge resistor 224a and a precharge circuit 224 which connects in parallel the series-connected circuits of the precharge relay 224b, and the control unit 23 is configured to be able to specify for each battery pack 22 whether or not to perform precharge, which closes the precharge relay 224b before closing the internal relay 220, and when a battery pack 22 designated as requiring precharge is connected to the electric device 20, a first connection process (third pre-stage process) S15 is performed in which the internal relay 220 of the battery pack 222 is closed after precharge, and when a battery pack 22 designated as not requiring precharge is connected to the electric device 20, a first connection process (first post-stage process) S19 is performed without performing precharge.

[0170] According to the above configuration, when the battery pack 22 that is specified as needing to be precharged is connected to the electric device 20, the first connection process (third pre-stage process) S15 is performed after the precharge, so that the battery pack 22 can be connected to the electric device 20 without any internal trouble (such as trouble caused by the influence of inrush current on the internal relay 220).

[0171] In contrast, when a battery pack 22 for which pre-charging is specified as not being required is connected to an electric device 20, pre-charging is omitted, so that the connection time of the battery pack 22 to the electric device 20 can be shortened.

[0172] Each of the multiple battery packs 22 has, as the internal relay 220, a first internal relay 220a arranged on the positive electrode side and a second internal relay 220b arranged on the negative electrode side, and the control unit 23 is configured to be able to specify whether or not to simultaneously close the first internal relay 220a and the second internal relay 220b in the first connection process (first subsequent process) S19, and when it is specified that the first internal relay 220a and the second internal relay 220b are simultaneously closed, the first internal relay 220a and the second internal relay 220b are simultaneously closed in the first connection process (first subsequent process) S19. In this way, even if the battery pack 22 has multiple relay switches (the first internal relay 220a, the second internal relay 220b) as the internal relay 220, if it is specified that they are simultaneously closed, the operation time of the internal relay 220 can be shortened and the battery pack 22 and the electric device 20 can be connected.

[0173] The control unit 23 specifies that the first battery pack 22, which is the first battery pack 22 to be connected to the electric device 20, among the multiple battery packs 22, be precharged, and specifies that the second battery pack 22, which is the second or subsequent battery pack 22 to be connected to the electric device 20, be omitted from precharge. In this way, even if the multiple battery packs 22 are connected to the electric device 20 in sequence, precharge of the second battery pack 22, which is the second or subsequent battery pack 22 to be connected to the electric device 20, is omitted, so that the processing time required for precharging the second or subsequent battery packs 22 is shortened, enabling a short startup time.

[0174] When the control unit 23 connects the battery pack 22 to be precharged to the electrical equipment 20, it performs a first pre-stage process S13 in which the external relay 211 corresponding to the battery pack 22 is closed, a second pre-stage process S15 in which the pre-charge relay 224b of the battery pack 22 is closed, and after the first pre-stage process S13 and the second pre-stage process S15, a third pre-stage process S15 in which the internal relay 220 of the battery pack 22 is closed.

[0175] In this way, the internal relay 220 is closed while the pre-charge is being executed, so that the effect of the inrush current is suppressed even if the internal relay 220 in the battery pack 22 is finally closed. That is, the inrush current acting when the internal relay 220 is closed is absorbed by the pre-charge resistor 224a, so that damage to the internal relay 220 is suppressed and damage to the battery pack 22 is prevented.

[0176] The electric work machine 1 further includes a working device 11 that performs a specified task. If the electric equipment 20 is configured to directly or indirectly drive the working device 11, diagnostic processing and pre-charging are omitted when the battery pack 22 is connected to the electric equipment 20, thereby shortening the start-up time of the working device 11.

[0177] In the method for starting an electric work machine 1 according to the above embodiment, the electric work machine 1 includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, and a plurality of battery packs 22... each having an internal relay 220 that opens and closes an internal circuit 222, the plurality of battery packs 22... being sequentially connected to the electric device 20 via the electric circuit 21 and connected in parallel, and the electric circuit 21 includes a plurality of external relays 211... corresponding to each of the plurality of battery packs 22... and opening and closing a circuit connecting the corresponding battery packs 22 and the electric device 20. The method for starting an electric work machine 1 includes a step of specifying for each battery pack 22 whether or not diagnostic processing of the opening and closing operation of the internal relays 220 of the battery packs 22 is required, and a connection step of connecting the battery packs 22 to the electric device 20, and in this connection step, diagnostic processing is performed for battery packs 22 specified as requiring diagnostic processing, and diagnostic processing is omitted for battery packs 22 specified as not requiring diagnostic processing.

[0178] According to the above method, in the process of specifying whether or not diagnostic processing of the opening and closing operation of the internal relay 220 of the battery pack 22 is required, for a battery pack 22 for which diagnostic processing of the opening and closing operation is specified to be required, diagnostic processing is performed in the connection process of connecting the battery pack 22 to the electrical equipment 20, so that the battery pack 22 can be connected to the electrical equipment 20 without any internal trouble in the battery pack 22 (such as trouble in the internal relay 220).

[0179] In contrast, in the step of specifying whether or not the diagnosis process for the opening and closing operation of the internal relay 220 of the battery pack 22 is required, the battery pack 22 for which the diagnosis process for the opening and closing operation is specified is In this regard, since the diagnostic process is omitted in the connection process of connecting the battery pack 22 to the electric device 20, the connection time of the battery pack 22 to the electric device 20 can be shortened.

[0180] In the method for starting the electric work machine 1 according to the above embodiment, a method for starting the electric work machine 1 includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, and a plurality of battery packs 22... each having an internal relay 220 that opens and closes an internal circuit 222, the plurality of battery packs 22... being sequentially connected to the electric device 20 via the electric circuit 21 and connected in parallel, the electric circuit 21 including a plurality of external relays 211... corresponding to each of the plurality of battery packs 22... and opening and closing a circuit connecting the corresponding battery pack 22 and the electric device 20, and each of the plurality of battery packs 22... is connected to the internal relay 220 via a pre-charge resistor 224a and a pre-charge relay 224b. The method for starting an electric work machine 1 having a precharge circuit 224 connecting series-connected circuits in parallel includes a step of specifying for each battery pack 22 whether or not to perform precharge by closing the precharge relay 224b before closing the internal relay 220, and a connection step of connecting the battery pack 22 to the electric equipment 20. In this connection step, for a battery pack 22 for which it is specified that precharge needs to be performed, a first connection process (third pre-stage process) S15 is performed in which the internal relay 220 of the battery pack 22 is closed after precharge is performed, and for a battery pack 22 for which it is specified that precharge does not need to be performed, a first connection process (first post-stage process) S19 is performed without performing precharge.

[0181] According to the above method, for a battery pack 22 for which it is specified that precharging is required in the process of specifying whether or not precharging is required for the battery pack 22, the first connection process (third pre-stage process) S15 is performed after precharging in the connection process of connecting the battery pack 22 to the electric device 20, so that the battery pack 22 can be connected to the electric device 20 in a state where there is no internal trouble in the battery pack 22 (such as trouble caused by the effect of inrush current on the internal relay 220).

[0182] In contrast, in the process of specifying for each battery pack 22 whether or not pre-charging is required, for battery packs 22 for which pre-charging is specified as not required, pre-charging is omitted in the connection process of connecting the battery pack 22 to the electrical equipment 20, so that the connection time of the battery pack 22 to the electrical equipment 20 can be shortened.

[0183] Furthermore, in the above embodiment, the electric operating machine 1 includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, a plurality of battery packs 22... each having positive and negative external terminals, the plurality of battery packs 22... being sequentially connected to the electric device 20 via the electric circuit 21 and connected in parallel, and a control unit 23, the electric circuit 21 including a plurality of external relays 211... corresponding to each of the plurality of battery packs 22... and configured to open and close a circuit connecting the corresponding battery pack 22 and the electric device 20, and the control unit 23 controls the battery packs 22 to be connected to the electric device 20 before the battery packs 22 are connected to the electric device 20. With the internal circuit 222 of the battery pack 22 to be diagnosed in the open state, an external relay diagnosis process is performed to diagnose whether or not the contacts of the external relay 211 corresponding to the battery pack 22 are stuck. In the external relay diagnosis process, with the internal circuit 222 of the battery pack 22 to be diagnosed being operated to the open state and the external relay 211 corresponding to the battery pack 22 being operated to the open state, if the voltage between the external terminals 223a, 223b of the positive and negative electrodes of the battery pack 22 is equal to or higher than a threshold value, it is determined that the contacts of the external relay 211 are stuck, and if the voltage between the external terminals 223a, 223b of the positive and negative electrodes of the battery pack 22 is lower than the threshold value, it is determined that the contacts of the external relay 211 are normal.

[0184] According to the above configuration, the multiple battery packs 22 are connected in parallel by being sequentially connected to the electric device 20, so that electricity from another battery pack 22 flows into a circuit connected to a battery pack 22. However, when the external relay 211 corresponding to a battery pack 22 is in an open state, the positive and negative external terminals 223a, 223b of that battery pack 22 are not affected by electricity from the other battery packs 22, and the voltage between the positive and negative external terminals 223a, 223b becomes lower than the threshold value.

[0185] On the other hand, if the contacts of the external relay 211 are stuck (welded), the external relay 211 is in a closed state (conductive state). If the external relay 211 corresponding to the battery pack 22 is in a closed state (conductive state), the positive and negative external terminals 223a, 223b of the battery pack 22 are affected by electricity from another battery pack 22, and the voltage between the positive and negative external terminals 223a, 223b becomes equal to or higher than the threshold value.

[0186] Therefore, by simply comparing the voltage between the positive and negative external terminals 223a, 223b of the battery pack 22 with a threshold value, it is possible to properly diagnose whether the contacts of the external relay 211 are stuck or not, without operating the external relay 211. As a result, with the electric work machine 1 configured as described above, it is possible to prevent the internal circuit 222 of the battery pack 22 from being damaged by the inrush current at the time of startup. In addition, it is also possible to properly determine whether a plurality of battery packs 22 can be connected in sequence.

[0187] For the first battery pack 22, which is the first battery pack to be connected to the electrical equipment 20 among the multiple battery packs 22..., the control unit 23 connects the first battery pack 22 to the electrical equipment 20 without performing external relay diagnosis processing of the external relay 211 corresponding to the first battery pack 22, and for the second battery pack 22, which is the second or subsequent battery pack to be connected to the electrical equipment 20, the control unit 23 performs external relay diagnosis processing of the external relay 211 corresponding to the second battery pack 22 before connecting the second battery pack 22 to the electrical equipment 20.

[0188] According to the above configuration, the first battery pack 22 is electrically connected to the electric device 20 without performing external relay diagnostic processing on the corresponding external relay 211. As a result, in a state where external relay diagnostic processing is performed on the external relay 211 corresponding to the second battery pack 22, electricity flows from the first battery pack 22 to the electric circuit 21. However, when the external relay 211 corresponding to the second battery pack 22 is in an open state, there is no effect of electricity from the first battery pack 22 on the positive and negative external terminals 223a, 223b of the second battery pack 22, and the voltage between the positive and negative external terminals 223a, 223b of the second battery pack 22 becomes lower than the threshold value.

[0189] On the other hand, if the contacts of the external relay 211 are stuck (welded), the external relay 211 is in a closed state (conductive state). If the external relay 211 corresponding to the second battery pack 22 is in a closed state (conductive state), the positive and negative external terminals 223a, 223b of the second battery pack 22 are affected by electricity from the first battery pack 22, and the voltage between the positive and negative external terminals 223a, 223b of the second battery pack 22 becomes equal to or higher than the threshold value.

[0190] Therefore, by simply comparing the voltage between the positive and negative external terminals 223a, 223b of the second battery pack 22 with a threshold value, it is possible to properly diagnose whether the contacts of the external relay 211 are stuck or not, without operating the external relay 211. As a result, with the electric work machine 1 configured as described above, it is possible to prevent the internal circuit 222 of the battery pack 22 from being damaged by the inrush current at the time of startup. In addition, it is also possible to properly determine whether a plurality of battery packs 22 can be connected in sequence.

[0191] In the above embodiment, when the control unit 23 determines in the external relay diagnosis process that the contact of the external relay 211 is stuck, it stops the electrical connection of the battery pack 22 corresponding to the external relay 211 to the electric device 20. In this way, power is not supplied to the electric device 20 from the battery pack 22 corresponding to the external relay 211 with the stuck contact, and an electrical accident is prevented in advance.

[0192] The battery pack 22 has a discharge circuit 225 that connects the positive external terminal side and the negative external terminal side of the internal circuit 222, the discharge circuit 225 including a discharge resistor 225a and a discharge relay 225b connected in series, and when the control unit 23 determines that the contact of the external relay 211 is normal in the external relay diagnostic process, it performs a discharge relay diagnostic process to diagnose whether or not the contact of the discharge relay 225b of the battery pack 22 is stuck, and in the discharge relay diagnostic process, operates the external relay 211 that is determined to be normal in the external relay diagnostic process to a closed state. Furthermore, the discharge relay 225b of the battery pack 22 is operated to an open state, and if the voltage between the positive and negative external terminals 223a, 223b of the battery pack 22 is above a threshold value and the voltage across the discharge circuit 225 is below a threshold value, it is determined that the contacts of the discharge relay 225b of the discharge circuit 225 are stuck, and if the voltage between the positive and negative external terminals 223a, 223b of the battery pack 22 is above a threshold value and the voltage across the discharge circuit 225 is higher than the threshold value, it is determined that the contacts of the discharge relay 225b of the discharge circuit 225 are normal.

[0193] Since the discharge circuit 225 connects the positive external terminal 223a side and the negative external terminal 223b side of the internal circuit 222, when the discharge relay 225b of the discharge circuit 225 is closed, the internal circuit 222 becomes a closed circuit, and if electricity is applied in this state, there is a risk that the discharge resistor 225a will be broken or the internal circuit 222 will be damaged.

[0194] However, in the above embodiment, since the open / close relay diagnostic process determines whether the contacts of the discharge relay 225b of the discharge circuit 225 are stuck, it is possible to prevent breakage of the discharge resistor 225a and damage to the internal circuit 222.

[0195] More specifically, as described above, when the external relay 211 corresponding to the battery pack 22 is in a closed state (conductive state), the positive and negative external terminals 223a, 223b of the battery pack 22 are affected by electricity from another battery pack 22, and the voltages of the positive and negative external terminals 223a, 223b become equal to or higher than a threshold value.

[0196] Since the discharge circuit 225 connects the positive external terminal 223a side and the negative external terminal 223b side of the internal circuit 222, when the discharge relay 225b is closed, the voltage across the discharge circuit 225 decreases. In other words, when the discharge relay 225b is closed, a current flows and the potential difference across the discharge circuit 225 decreases (or disappears), so that the voltage across the discharge circuit 225 becomes equal to or lower than the threshold value.

[0197] In contrast, when the discharge relay 225b of the discharge circuit 225 is opened, the voltage across the discharge circuit 225 becomes high (the voltage rises). That is, when the discharge relay 225b of the discharge circuit 225 is opened, the discharge circuit 225 is disconnected, and as a result, a voltage (potential difference) is generated on both sides (positive side and negative side) of the discharge relay 225b. That is, when the discharge relay 225b is opened, the voltage (potential difference) across the discharge circuit 225 rises and becomes larger (higher) than the threshold value.

[0198] In this way, it is possible to properly diagnose whether the contacts of the discharge relay 225b of the discharge circuit 225 are stuck or not based on the voltages across the external terminals 223a, 223b and the discharge circuit 225, and it is possible to prevent damage to the internal circuit 222 and the discharge circuit 225 (discharge resistor 225a).

[0199] In the above embodiment, the electric operating machine 1 includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, a plurality of battery packs 22... having positive and negative external terminals, the plurality of battery packs 22... being sequentially connected to the electric device 20 via the electric circuit 21 and connected in parallel, and a control unit 23, the electric circuit 21 including a plurality of external relays 211... corresponding to the plurality of battery packs 22..., respectively, and opening and closing a circuit connecting the corresponding battery packs 22 and the electric device 20, the battery packs 22 having a discharge circuit 225 connecting the negative external terminal side and the positive external terminal side of the internal circuit 222, the discharge circuit 225 including a discharge resistor 225a and a discharge relay 225b connected in series, and when connecting the battery pack 22 to the electric device 20, the control unit 23 A discharge relay diagnostic process is performed to diagnose whether or not the contacts of the discharge relay 225b of the battery pack 22 are stuck. In the discharge relay diagnostic process, the external relay 211 corresponding to the battery pack 22 to be diagnosed is operated to a closed state, and the discharge relay 225b of the battery pack 22 is operated to an open state. If the voltage between the positive and negative external terminals 223a, 223b of the battery pack 22 is equal to or higher than a threshold value and the voltage across the discharge circuit 225 is equal to or lower than a threshold value, it is determined that the contacts of the discharge relay 225b of the discharge circuit 225 are stuck. If the voltage between the positive and negative external terminals 223a, 223b of the battery pack 22 is equal to or higher than a threshold value and the voltage across the discharge circuit 225 is higher than the threshold value, it is determined that the contacts of the discharge relay 225b of the discharge circuit 225 are normal.

[0200] In the above configuration, when the external relay 211 corresponding to the battery pack 22 is in a closed state (conductive state), the positive and negative external terminals 223a, 223b of the battery pack 22 are affected by electricity from another battery pack 22, and the voltages of the positive and negative external terminals 223a, 223b become equal to or higher than a threshold value.

[0201] Since the discharge circuit 225 connects the positive external terminal 223a side and the negative external terminal 223b side of the internal circuit 222, when the discharge relay 225b is closed, the voltage across the discharge circuit 225 decreases. In other words, when the discharge relay 225b is closed, a current flows and the potential difference across the discharge circuit 225 decreases (or disappears), so that the voltage across the discharge circuit 225 becomes equal to or lower than the threshold value.

[0202] In contrast, when the discharge relay 225b of the discharge circuit 225 is opened, the voltage across the discharge circuit 225 becomes high (the voltage rises). That is, when the discharge relay 225b of the discharge circuit 225 is opened, the discharge circuit 225 is disconnected, and as a result, a voltage (potential difference) is generated on both sides (positive side and negative side) of the discharge relay 225b. That is, when the discharge relay 225b is opened, the voltage (potential difference) across the discharge circuit 225 rises and becomes larger (higher) than the threshold value.

[0203] In this way, based on the voltages across the external terminals 223a and 223b and the discharge circuit 225, it is possible to determine whether the contacts of the discharge relay 225b of the discharge circuit 225 are stuck or not. The diagnosis can be performed appropriately, and damage to the internal circuit 222 and the discharge circuit 225 (the discharge resistor 225a) can be prevented in advance.

[0204] In the above embodiment, when the control unit 23 determines in the discharge relay diagnosis process that the contact of the discharge relay 225b is stuck, it stops the electrical connection of the battery pack 22 including the discharge relay 225b determined to be stuck to the electric device 20. In this way, power is not supplied to the electric device 20 from the battery pack 22 having the discharge relay 225b with the stuck contact, and an electrical accident is prevented.

[0205] In the above embodiment, the method for starting the electric working machine 1 includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, and a plurality of battery packs 22... having positive and negative external terminals, the plurality of battery packs 22... being sequentially connected to the electric device 20 via the electric circuit 21 and connected in parallel, and the electric circuit 21 including a plurality of external relays 211... corresponding to each of the plurality of battery packs 22... and opening and closing a circuit connecting the corresponding battery packs 22 and the electric device 20, With the internal circuit 222 of the battery pack 22 in an open state, an external relay diagnosis process is performed to diagnose whether the contacts of the external relay 211 corresponding to the battery pack 22 are stuck or not. In the external relay diagnosis process, with the internal circuit 222 of the battery pack 22 to be diagnosed being operated to an open state and the external relay 211 corresponding to the battery pack 22 being operated to an open state, if the voltage between the external terminals 223a, 223b of the positive and negative electrodes of the battery pack 22 is equal to or higher than a threshold value, it is determined that the contacts of the external relay 211 are stuck, and if the voltage between the external terminals 223a, 223b of the positive and negative electrodes of the battery pack 22 is lower than the threshold value, it is determined that the contacts of the external relay 211 are normal.

[0206] According to the premise of the above method, the multiple battery packs 22 are connected in parallel by being sequentially connected to the electric device 20, so that electricity from another battery pack 22 flows into a circuit connected to a battery pack 22. However, when the external relay 211 corresponding to a battery pack 22 is in an open state, the positive and negative external terminals 223a, 223b of that battery pack 22 are not affected by electricity from the other battery packs 22, and the voltage between the positive and negative external terminals 223a, 223b becomes lower than the threshold value.

[0207] On the other hand, if the contacts of the external relay 211 are stuck (welded), the external relay 211 is in a closed state (conductive state). If the external relay 211 corresponding to the battery pack 22 is in a closed state (conductive state), the positive and negative external terminals 223a, 223b of the battery pack 22 are affected by electricity from another battery pack 22, and the voltage between the positive and negative external terminals 223a, 223b becomes equal to or higher than the threshold value.

[0208] Therefore, according to the above method, it is possible to properly diagnose whether the contacts of the external relay 211 are stuck or not by simply comparing the voltage between the positive and negative external terminals 223a, 223b of the battery pack 22 with a threshold value, without operating the external relay 211. As a result, according to the electric work machine 1 configured as above, it is possible to prevent the internal circuit 222 of the battery pack 22 from being damaged by the influence of the inrush current at the time of startup. In addition, it is also possible to properly determine whether a plurality of battery packs 22 can be connected in sequence.

[0209] In the above embodiment, the method for starting the electric working machine 1 includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, and a plurality of battery packs 22... having positive and negative external terminals, the plurality of battery packs 22... being sequentially connected to the electric device 20 via the electric circuit 21 and connected in parallel, the electric circuit 21 including a plurality of external relays 211... corresponding to each of the plurality of battery packs 22... and opening and closing a circuit connecting the corresponding battery pack 22 and the electric device 20, the battery pack 22 including a discharge circuit 225 connecting the negative external terminal side and the positive external terminal side of the internal circuit 222, the discharge circuit 225 including a discharge resistor 225a and a discharge relay 225b connected in series, At that time, a discharge relay diagnostic process is performed to diagnose whether or not the contacts of the discharge relay 225b of the battery pack 22 are stuck. In the discharge relay diagnostic process, the external relay 211 corresponding to the battery pack 22 to be diagnosed is operated to a closed state, and the discharge relay 225b of the battery pack 22 is operated to an open state. If the voltage between the external terminals 223a, 223b of the positive and negative electrodes of the battery pack 22 is equal to or higher than a threshold value and the voltage across the discharge circuit 225 is equal to or lower than a threshold value, it is determined that the contacts of the discharge relay 225b of the discharge circuit 225 are stuck. If the voltage between the external terminals 223a, 223b of the positive and negative electrodes of the battery pack 22 is equal to or higher than a threshold value and the voltage across the discharge circuit 225 is higher than the threshold value, it is determined that the contacts of the discharge relay 225b of the discharge circuit 225 are normal.

[0210] In the configuration assumed by the above method, when the external relay 211 corresponding to the battery pack 22 is in a closed state (conductive state), the positive and negative external terminals 223a, 223b of the battery pack 22 are affected by electricity from another battery pack 22, and the voltages of the positive and negative external terminals 223a, 223b become equal to or higher than a threshold value.

[0211] Since the discharge circuit 225 connects the positive external terminal 223a side and the negative external terminal 223b side of the internal circuit 222, when the discharge relay 225b is closed, the voltage across the discharge circuit 225 decreases. In other words, when the discharge relay 225b is closed, a current flows and the potential difference across the discharge circuit 225 decreases (or disappears), so that the voltage across the discharge circuit 225 becomes equal to or lower than the threshold value.

[0212] In contrast, when the discharge relay 225b of the discharge circuit 225 is opened, the voltage across the discharge circuit 225 becomes high (the voltage rises). That is, when the discharge relay 225b of the discharge circuit 225 is opened, the discharge circuit 225 is disconnected, and as a result, a voltage (potential difference) is generated on both sides (positive side and negative side) of the discharge relay 225b. That is, when the discharge relay 225b is opened, the voltage (potential difference) across the discharge circuit 225 rises and becomes larger (higher) than the threshold value.

[0213] In this manner, the method of the above configuration can properly diagnose whether or not the contacts of the discharge relay 225b of the discharge circuit 225 are stuck based on the voltages across the external terminals 223a, 223b and the discharge circuit 225, and can prevent damage to the internal circuit 222 and the discharge circuit 225 (discharge resistor 225a).

[0214] In the above embodiment, the electric work machine 1 includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, a plurality of battery packs 22... connected to the electric device 20 via the electric circuit 21, and a control unit 23. The control unit 23 has a drive mode in which the electric device 20 is driven by power supplied from the battery packs 22, and a charge mode in which the battery pack 22 is charged. In the drive mode, when a voltage difference between the plurality of battery packs 22... exceeds a preset reference value, only the battery pack 22 with the highest voltage among the plurality of battery packs 22... is connected to the electric device 20 to drive the electric device 20. Can.

[0215] According to the above configuration, in the drive mode, when the voltage difference between the battery packs 22 exceeds a reference value, i.e., when the battery packs 22 are connected in parallel, a flow of electricity occurs between the battery packs 22, 22, and the flow is expected to exceed an allowable value, the battery pack 22 with the highest voltage is connected to the electric device 20 to drive the electric device 20. This prevents the battery packs 22 with a large voltage difference from being connected in parallel, prevents damage to the battery pack 22, and ensures the supply of power to the electric device 20. In other words, the electric work machine 1 configured as above can prevent the battery pack 22 from breaking down due to the parallel connection of the battery packs 22.

[0216] The control unit 23 starts driving the electric device 20 by connecting only the battery pack 22 with the highest voltage to the electric device 20, and then, when the voltage difference between the battery pack 22 and the other battery packs 22 becomes less than a reference value, connects the battery pack 22 to the other battery packs 22 to drive the electric device 20. In this way, the multiple battery packs 22 supply power to the electric device 20 in a state where the voltage difference between the multiple battery packs 22 is small (or disappears). As a result, power can be efficiently supplied to the electric device 20 without electricity flowing between the battery packs 22, 22 due to the voltage difference between the battery packs 22, 22.

[0217] The electric work machine 1 further includes an alarm means 142 for notifying the operator, and when the voltage difference between the multiple battery packs 22 exceeds a reference value, the control unit 23 causes the alarm means 142 to notify the operator that the battery packs 22 need to be charged.

[0218] According to the above configuration, the notification means 142 can prompt the user to charge the battery pack 22, thereby enabling the battery pack 22 to be charged quickly. In particular, by providing a notification to prompt the user to charge using the notification means 142, the timing to charge the battery pack 22 can be brought forward, and the battery pack 22 with a low voltage can be quickly restored.

[0219] In the charging mode, when the voltage difference among the battery packs 22 exceeds a preset reference value, the control unit 23 performs charging processing on only the battery pack 22 with the lowest voltage among the battery packs 22. In this way, only the battery pack 22 with the lowest voltage is charged, and the voltage of only the battery pack 22 with the lowest voltage increases. This reduces (or eliminates) the difference in voltage between the battery pack 22 that is the charge target and the other battery packs 22 that are not the charge target. This suppresses the flow of electricity between the battery packs 22, 22 when the battery packs 22 are connected in parallel to supply power to the electric device 20, and power is efficiently supplied to the electric device 20.

[0220] In the above embodiment, the electric work machine 1 comprises an electric equipment 20, an electric circuit 21 electrically connected to the electric equipment 20, a plurality of battery packs 22... connected to the electric equipment 20 via the electric circuit 21, and a control unit 23. The control unit 23 has a drive mode in which the electric equipment 20 is driven by power supplied from the battery pack 22, and a charge mode in which the battery pack 22 is charged. In the charge mode, when the voltage difference between the plurality of battery packs 22... exceeds a predetermined reference value, a charging process is performed with only the battery pack 22 with the lowest voltage among the plurality of battery packs 22... as the target for charging.

[0221] According to the above configuration, in the charging mode, only the battery pack 22 with the lowest voltage is charged, so that the voltage of only that battery pack 22 becomes high. The difference in voltage between the battery pack 22 that is the target for charging and the other battery packs 22 that are not the target for charging becomes small (or disappears). As a result, when a plurality of battery packs 22 are connected in parallel to supply power to the electric device 20, the flow of electricity between the battery packs 22, 22 is suppressed, and power is efficiently supplied to the electric device 20.

[0222] The control unit 23 starts a charging process with only the battery pack 22 with the lowest voltage as the charging target, and then, when the voltage difference between the battery pack 22 and the other battery packs 22 falls below a reference value, performs a charging process with the battery pack 22 and the other battery packs 22 as the charging targets. In this way, the charging process increases the voltage of the battery pack 22 with the lowest voltage, and approaches the voltage of the other battery packs 22.

[0223] As a result, when the voltage difference between the battery packs 22 falls below the reference value, the voltage difference becomes small or disappears. In this state, the other battery packs 22 are also charged, so that the multiple battery packs 22 are charged with no (small) voltage difference. Therefore, when the multiple battery packs 22 are connected to the electric device 20, power is efficiently supplied from the multiple battery packs 22 to the electric device 20 with the flow of electricity between the battery packs 22, 22 being suppressed.

[0224] The electric work machine 1 further includes a charging inlet 25 that is connectable to a charging device and is electrically connected to a plurality of battery packs 22... via an electric circuit 21, and the control unit 23 executes the charging mode when a charging device is connected to the charging inlet 25. In this way, the mode is automatically switched to the charging mode without the operator having to switch the mode.

[0225] The electric circuit 21 includes a plurality of external relays 211... corresponding to the plurality of battery packs 22..., which open and close the circuit connecting the corresponding battery packs 22 and the charging inlet 25, and in the charging mode, the control unit 23 closes the external relays 211 corresponding to the battery packs 22 to be charged, and opens the external relays 211 corresponding to the battery packs 22 not to be charged. In this way, the path for supplying power from the battery packs 22 to the electric device 20 can be used as the charging path, and only the battery packs 22 to be charged can be charged.

[0226] As described above, the electric working machine 1 having a drive mode and a charge mode further includes the working device 11 that performs a predetermined task, and the electric device 20 directly or indirectly drives the working device 11. In this way, power is supplied to the electric device from at least the battery pack with a high voltage (large remaining charge), so that the electric device can be stably driven for a long time.

[0227] In the above embodiment, the method for starting an electric work machine 1 includes an electric device 20, an electric circuit 21 electrically connected to the electric device 20, and a plurality of battery packs 22... connected to the electric device 20 via the electric circuit 21, and has a drive mode in which the electric device 20 is driven by power supplied from the battery pack 22, and a charging mode in which the battery pack 22 is charged.In the drive mode, when the voltage difference between the plurality of battery packs 22... exceeds a predetermined reference value, only the battery pack 22 with the highest voltage among the plurality of battery packs 22... is connected to the electric device 20 to drive the electric device 20.

[0228] According to the above method, in the drive mode, when the voltage difference between the multiple battery packs 22 exceeds a reference value, that is, when the multiple battery packs 22 are connected in parallel and it is expected that the flow of electricity will occur between the battery packs 22, 22 and that the flow will exceed an allowable value, the battery pack 22 with the highest voltage is connected to the electric device 20 to drive the electric device 20. Can.

[0229] This prevents battery packs 22 with a large voltage difference from being connected in parallel, prevents damage to the battery packs 22, and ensures power supply to the electric device 20. In other words, the electric work machine 1 configured as described above can prevent failure of the battery packs 22 caused by connecting a plurality of battery packs 22 in parallel.

[0230] In the above embodiment, the method for starting the electric work machine 1 is a charging method for the electric work machine 1, which comprises an electric device 20, an electric circuit 21 electrically connected to the electric device 20, and a plurality of battery packs 22... connected to the electric device 20 via the electric circuit 21, and has a drive mode in which the electric device 20 is driven by power supplied from the battery pack 22, and a charging mode in which the battery pack 22 is charged.In the charge mode, when the voltage difference between the plurality of battery packs 22... exceeds a predetermined reference value, a charging process is performed with only the battery pack 22 with the lowest voltage among the plurality of battery packs 22... as the target for charging.

[0231] According to the above method, in the charging mode, only the battery pack 22 with the lowest voltage is charged, and therefore the voltage of only that battery pack 22 becomes high. This reduces (or eliminates) the difference in voltage between the battery pack 22 to be charged and the other battery packs 22 that are not to be charged. This suppresses the flow of electricity between the battery packs 22, 22 when a plurality of battery packs 22 are connected in parallel to supply power to the electric device 20, and power is efficiently supplied to the electric device 20.

[0232] It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that appropriate modifications can be made without departing from the gist of the present invention.

[0233] In the above embodiment, the two battery packs 22 are connected in parallel, but this is not limited thereto. For example, the electric work machine 1 may include three or more battery packs 22, which are connected in parallel to supply power to the electric device 20. In other words, it is sufficient to connect a plurality of battery packs 22 in parallel in order to reduce the current value of each battery pack 22, and the number of battery packs 22 is not limited thereto.

[0234] In this case as well, the control (processing) for the connected first battery pack 22 and the control (processing) for the connected second battery pack 22 are similar to those in the above embodiment.

[0235] In the above embodiment, the control unit 23 sets the battery pack 22 corresponding to the external relay 211 with the greatest number of opening and closing counts as the external relay 211 corresponding to the second battery pack 22 as the first battery pack 22 (the battery pack 22 that is the first to be connected) based on the cumulative number of opening and closing of each of the multiple external relays 211..., but is not limited to this. For example, the control unit 23 may sequentially change the battery pack 22 set as the first battery pack 22 every time it is started up (every time it performs a process of connecting the multiple battery packs 22... and the electric device 20). In this way, damage received by each of the multiple external relays 211... can be equalized, as in the above embodiment.

[0236] Specifically, the damage that the external relay 211 receives varies depending on the number of times it is opened and closed. That is, when the number of times it is opened and closed increases, the external relay 211 receives greater damage due to the opening and closing of the circuit, whereas when the number of times it is opened and closed decreases, the external relay 211 receives less damage due to the opening and closing of the circuit. Therefore, every time the electric device 20 is started, the external relay 211 receives a large amount of power from the external relay 211 connected to the electric device 20 (electrical circuit 21). By sequentially changing the first battery pack 22, the external relay 211 that is first closed is also changed, so that the damage received by each of the multiple external relays 211 can be equalized. This makes it possible to prevent a specific external relay 211 from breaking down.

[0237] In the above embodiment, a crawler-type running mechanism is adopted as the running mechanism 101, but this is not limited thereto. For example, the running mechanism 101 may be a wheel (tire)-type running mechanism having a pair of wheels at the front and rear. In this case, both the front and rear wheels may be driven, or either one of the front and rear wheels may be driven.

[0238] In the above embodiment, each of the multiple battery packs 22... includes the precharge circuit 224, but this is not limiting. For example, when a specific battery pack 22 is connected first to the electric device 20 (electric circuit 21), at least only the battery pack 22 set to be first in the order may include a precharge circuit 224 in which a precharge resistor 224a and a precharge relay 224b are connected in parallel to the internal relay 220 (220a). However, it goes without saying that, when the battery pack 22 set to be first is changed as in the above embodiment, each of the multiple battery packs 22... must include the precharge circuit 224.

[0239] In the above embodiment, the electric working machine 1 includes, as the control unit 23, an ECU 23a that controls the entire electric working machine 1 and a BMS 23b that monitors and controls the battery pack 22, and the ECU 23a executes various processes, but this is not limiting. For example, the parallel connection feasibility diagnosis, parallel connection processing of the battery pack 22, single connection processing of the battery pack 22, fault diagnosis, and charging mode may be executed (processed) by the BMS 23b, or may be executed (processed) by the ECU 23a and the BMS 23b in a shared manner. Furthermore, as the control unit 23, in addition to the ECU 23a and the BMS 23b, a dedicated control unit (controller unit) that executes the parallel connection feasibility diagnosis, parallel connection processing of the battery pack 22, single connection processing of the battery pack 22, fault diagnosis, and charging mode may be provided.

[0240] In the above embodiment, each of the battery packs 22 has the first internal relay 220a and the second internal relay 220b as the internal relay 220, but is not limited to this. For example, each of the battery packs 22 may have either the first internal relay 220a or the second internal relay 220b as the internal relay 220. In other words, each of the battery packs 22 may have at least one internal relay 220 that opens and closes the internal circuit 222.

[0241] In the above embodiment, each of the battery packs 22... has the first internal relay 220a on the positive (P) side and the second internal relay 220b on the negative (N) side as the internal relay 220, and has the precharge circuit 224 (precharge resistor 224a, precharge relay 224b) connected in parallel to the first internal relay 220a on the positive (P) side. When the first battery pack 22 is connected to the electric device 20, the second internal relay 220b on the negative (N) side and the precharge relay 224b of the precharge circuit 224 are closed together (simultaneously). However, this is not limited to this. For example, when the first battery pack 22 is connected to the electric device 20, the second internal relay 220b on the negative (N) side and the precharge relay 224b of the precharge circuit 224 may be closed at different timings. However, in this case, it is assumed that the internal relay 220 (first internal relay 220a on the positive (P) side) in parallel with the precharge circuit 224 is closed last. Also, if the battery pack 22 has one internal relay 220 that opens and closes the internal circuit 222, and has a precharge circuit 224 connected in parallel to the one internal relay 220, the internal relay 220 may be closed after the precharge relay 224b of the precharge circuit 224 is closed.

[0242] In the above embodiment, the second pre-stage process S15 is performed after the first pre-stage process S13, but is not limited to this. That is, after the external relay 211 corresponding to the first battery pack 22 for the electric device 20 is closed, the internal relay 220 (first internal relay 220a) parallel to the pre-charge circuit 224 (pre-charge relay 224b) is closed, but is not limited to this. For example, after the pre-charge circuit 224 (pre-charge relay 224b) of the first battery pack 22 for the electric device 20 is closed, the external relay 211 corresponding to the battery pack 22 may be closed. Also, the pre-charge circuit 224 (pre-charge relay 224b) of the first battery pack 22 and the external relay 211 corresponding to the battery pack 22 may be closed simultaneously for the electric device 20. That is, the order of the first pre-stage process S13 and the second pre-stage process S15 may be interchanged, or the first pre-stage process S13 and the second pre-stage process S15 may be performed at the same timing.

[0243] However, in any of the above cases, it is assumed that the internal relay 220 (first internal relay 220a) in parallel with the precharge circuit 224 (precharge relay 224b) is closed after the precharge circuit 224 (precharge relay 224b) is closed (after precharge is executed). In other words, it is assumed that the third pre-stage process S15 is performed after the first pre-stage process S13 and the second pre-stage process S15. Also, in order to reliably execute precharge, it goes without saying that it is preferable to close the precharge circuit 224 (precharge relay 224b) after closing the external relay 211, as in the above embodiment.

[0244] In the above embodiment, the storage unit of the ECU 23a as the control unit 23 stores designations regarding whether or not to diagnose the opening and closing operation of the internal relay 220 of the second battery pack 22, designations regarding whether or not to perform precharging in the precharge circuit 224 of the second battery pack 22, and designations regarding whether or not to simultaneously close the first internal relay 220a and the second internal relay 220b, but this is not limited thereto. For example, the storage unit of the ECU 23a may store only designations regarding whether or not to diagnose the opening and closing operation that requires processing time when connecting multiple battery packs 22. Also, as described above, the designations stored in the storage unit may be changeable and limited to fixed contents.

[0245] In the above embodiment, the battery packs 22... and the electric devices 20... are electrically connected via the electric circuit 21, but the present invention is not limited thereto. For example, the battery packs 22... and a single electric device 20 may be connected via the electric circuit 21. That is, as long as the battery packs 22... are connected in parallel, the number of electric devices 20 (electric devices 20 for output) to which power is supplied from the battery packs 22... does not matter. Needless to say, the secondary circuits 212 of the electric circuit 21 are provided in the number of systems corresponding to the number of the electric devices 20. Therefore, when a single electric device 20 is connected to the battery packs 22... as described above, the secondary circuit 212 becomes one system (one set of the positive secondary circuit 212a and the negative secondary circuit 212b).

[0246] In the above embodiment, when the first battery pack 22 is connected to the electric device 20, a diagnosis process of the opening and closing operation of the internal relay 220 is performed, and after a first pre-stage process of closing the external relay 211 corresponding to the first battery pack 22, a third pre-stage process of closing the internal relay 220 of the first battery pack 22 is performed, but this is not limiting. For example, when the first battery pack 22 is connected to the electric device 20, it may be unnecessary (not performed) to specify whether or not to perform a diagnosis process of the opening and closing operation of the internal relay 220.

[0247] In addition, when the first battery pack 22 is connected to the electric device 20, the internal relay 220 is opened and closed. After performing a diagnostic process of the operation and performing a third pre-stage process for closing the internal relay 220 of the first battery pack 22, a first pre-stage process for closing the external relay 211 corresponding to the first battery pack 22 may be performed. However, when pre-charging is performed, if a second pre-stage process for performing pre-charging is performed between the first pre-stage process and the third pre-stage process, it is possible to prevent the relay switch (the internal relay 220 or the external relay 211) that is last closed from being affected by the inrush current.

[0248] In the above embodiment, when the first battery pack 22 is connected to the electric device 20, pre-charging is performed, but the present invention is not limited to this. For example, when the first battery pack 22 is connected to the electric device 20, it is possible to connect the first battery pack 22 to the electric device 20 without specifying whether or not pre-charging is required (not performed). In this case, similar to the second battery pack 22, after the internal relay 220 of the first battery pack 22 is set to a closed state (after the first connection process is performed), the external relay 211 corresponding to the first battery pack 22 may be set to a closed state (the second connection process is performed) so that an inrush current does not act on the internal relay 220.

[0249] In the above embodiment, the first internal relay 220a and the second internal relay 220b are closed together (simultaneously) in the opening and closing of the internal relay 220 of the second battery pack 22 when the second battery pack 22 is connected to the electric device 20, but this is not limiting. For example, in the opening and closing of the internal relay 220 of the second battery pack 22 when the second battery pack 22 is connected to the electric device 20, the first internal relay 220a may be closed after the second internal relay 220b is closed.

[0250] Furthermore, the first internal relay 220a and the second internal relay 220b may be closed together (simultaneously) for the first battery pack 22. That is, when the internal relay 220 of the battery pack 22 includes the first internal relay 220a and the second internal relay 220b, and is configured to be able to specify whether or not to close the first internal relay 220a and the second internal relay 220b simultaneously in the first connection process for closing the internal relay 220, the first internal relay 220a and the second internal relay 220b may be closed according to the specification.

[0251] Therefore, in the first connection process for closing the internal relay 220, if it is specified that the first internal relay 220a and the second internal relay 220b are to be closed simultaneously, the first internal relay 220a and the second internal relay 220b may be closed simultaneously (together). Conversely, in the first connection process for closing the internal relay 220, if it is specified that the first internal relay 220a and the second internal relay 220b are not to be closed simultaneously, the first internal relay 220a and the second internal relay 220b may be closed at different times. In the above embodiment, as a method of correcting the voltage difference among the multiple battery packs 22, only the battery pack 22 with the lowest voltage is charged, and when the voltage of that battery pack 22 becomes equivalent to the voltage of the battery pack 22 with the highest voltage, charging of the battery pack 22 with the highest voltage is also started. However, for example, the control unit 53 may connect only the battery pack 22 with the highest voltage to the electric device 20 and start driving the electric device 20, and then, when the voltage difference between the battery pack (the battery pack supplying power) 20 connected to the electric device 20 and the other battery pack (the low-voltage battery pack 22 not supplying power) becomes less than a reference value, connect the battery pack (the battery pack supplying power) 20 connected to the electric device 20 and the other battery pack (the low-voltage battery pack 22 not supplying power) to the electric device 20 to drive the electric device 20.

[0252] In this way, the voltage difference between the multiple battery packs 22, 22 is small. In a state in which a plurality of battery packs 22 are connected to the electric device 20, the flow of electricity between the battery packs 22, 22 is prevented, and damage to the battery packs 22 can be suppressed.

[0253] Although not specifically mentioned in the above embodiment, the inverter 20a as the electric device 20 drives the electric motor 16 which drives the hydraulic pump 15, and therefore indirectly drives the working device 11, but the electric device 20 that drives the working device 11 is not limited to one that indirectly drives the working device 11. For example, the electric device 20 that drives the working device 11 may be an electric actuator that directly drives the working device 11 and is supplied with power directly from a battery pack 22...

[0254] In the above embodiment, the electric work machine 1 includes, as the working device 11, a shovel device 11b in which a bucket 112b is connected to the tip of an arm 111b, but is not limited thereto. For example, the shovel device 11b may include a bucket 112b as a basic configuration, and the bucket 112b may be replaceable with another working tool. Furthermore, the working device 11 may be a dedicated working device in which another working tool is connected to the tip of the arm 111b configured as the shovel device 11b. Here, examples of the other working tools include a hydraulic breaker, a hydraulic crusher, an angle broom, an earth auger, a pallet fork, a sweeper, a mower, a snow blower, and the like.

[0255] In the above embodiment, the electric work machine 1 for construction having the dozer device 11a and the shovel device 11b has been described as the working device 11, but the present invention is not limited to this. For example, the electric work machine 1 may be an electric work machine 1 for transport or an electric work machine 1 for agriculture. In other words, the electric work machine 1 is not limited to a construction machine, but may be a transport machine (e.g., a forklift) or an agricultural machine (e.g., a tractor), etc. [Explanation of symbols]

[0256] 1: Electric work equipment 20: Electrical equipment (electrical equipment for output) 21: Electrical circuits 22: Battery pack 23: Control section 24: Junction box 25: Charging inlet (electrical input device) 142: Monitor (notification means) 211: External relay 220: Internal relay 220a: First internal relay 220b: Second internal relay 222: Internal circuit 224: Precharge circuit 224a: Precharge resistor 224b: Precharge relay 225: Discharge circuit 225a: Discharge resistor 225b: Discharge relay

Claims

1. Electrical equipment and an electrical circuit electrically connected to the electrical device; a plurality of battery packs each having positive and negative external terminals, the battery packs being sequentially connected to the electric device via the electric circuit and connected in parallel; A control unit, The electrical circuit includes: a plurality of external relays corresponding to the plurality of battery packs, the plurality of external relays opening and closing a circuit connecting the corresponding battery pack and the electric device; The control unit is Before the battery pack is connected to the electric device, an external relay diagnosis process is performed to diagnose whether or not a contact of the external relay corresponding to the battery pack is stuck while an internal circuit of the battery pack is in an open state; In the external relay diagnosis process, An electric work machine in which, when the internal circuit of the battery pack to be diagnosed is operated to an open state and the external relay corresponding to the battery pack is operated to an open state, if the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than a threshold value, it is determined that the contacts of the external relay are stuck, and if the voltage between the external terminals of the positive and negative electrodes of the battery pack is lower than the threshold value, it is determined that the contacts of the external relay are normal.

2. The control unit is a first battery pack that is a first battery pack to be connected to the electrical device among the plurality of battery packs is connected to the electrical device without performing the external relay diagnosis process on the external relay corresponding to the first battery pack; An electric work machine as described in claim 1, wherein for a second battery pack which is the second or subsequent battery pack among the plurality of battery packs, an external relay diagnostic process is performed on the external relay corresponding to the second battery pack before the second battery pack is connected to the electrical equipment.

3. The control unit is 2. The electric operating machine according to claim 1, wherein, when it is determined in the external relay diagnosis process that a contact of the external relay is stuck, electrical connection of the battery pack corresponding to the external relay to the electrical device is discontinued.

4. The battery pack includes: a discharge circuit connecting a positive external terminal side and a negative external terminal side of the internal circuit, the discharge circuit including a discharge resistor and a discharge relay connected in series; The control unit is When it is determined that the contact of the external relay is normal in the external relay diagnosis process, a discharge relay diagnosis process is performed to diagnose whether or not a contact of the discharge relay of the battery pack is stuck; In the discharge relay diagnosis process, The external relay determined to be normal in the external relay diagnosis process is operated to a closed state, and the discharge relay of the battery pack is operated to an open state; When the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than the threshold value and the voltage across the discharge circuit is equal to or lower than the threshold value, it is determined that the contact of the discharge relay of the discharge circuit is stuck, and when the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than the threshold value and the voltage across the discharge circuit is equal to or lower than the threshold value, 2. The electric operating machine according to claim 1, wherein when the detected voltage is higher than the threshold voltage, it is determined that the contacts of the discharge relay of the discharge circuit are normal.

5. Electrical equipment and an electrical circuit electrically connected to the electrical device; a plurality of battery packs each having positive and negative external terminals, the battery packs being sequentially connected to the electric device via the electric circuit and connected in parallel; A control unit, The electrical circuit includes: a plurality of external relays corresponding to the plurality of battery packs, the plurality of external relays opening and closing a circuit connecting the corresponding battery pack and the electric device; The battery pack includes: a discharge circuit connecting a negative external terminal side and a positive external terminal side in an internal circuit of the battery pack, the discharge circuit including a discharge resistor and a discharge relay connected in series; The control unit is When the battery pack is connected to the electric device, a discharge relay diagnosis process is performed to diagnose whether or not a contact of the discharge relay of the battery pack is stuck; In the discharge relay diagnosis process, The external relay corresponding to the battery pack to be diagnosed is operated to a closed state, and the discharge relay of the battery pack is operated to an open state; An electric work machine that determines that the contacts of the discharge relay of the discharge circuit are stuck when the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than the threshold value and the voltage across the discharge circuit is equal to or lower than the threshold value, and determines that the contacts of the discharge relay of the discharge circuit are normal when the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than the threshold value and the voltage across the discharge circuit is higher than the threshold value.

6. The control unit is An electric operating machine as described in claim 4 or 5, wherein, if it is determined in a discharge relay diagnostic process that the contacts of the discharge relay are stuck, the electrical connection of the battery pack having the discharge relay determined to be stuck to the electrical equipment is discontinued.

7. The control unit is The electric operating machine according to claim 2 , wherein the battery pack corresponding to the external relay having the largest cumulative number of openings and closings among the plurality of external relays is set as the first battery pack.

8. The control unit is The electric operating machine according to claim 2 , wherein the first battery pack is changed in sequence from among the plurality of battery packs every time a process for connecting the plurality of battery packs to the electric device is performed.

9. Further comprising a work device for performing a predetermined work, The electric operating machine according to claim 1 or 5, wherein the electric device directly or indirectly drives the operating device.

10. Electrical equipment and an electrical circuit electrically connected to the electrical device; a plurality of battery packs each having positive and negative external terminals, the battery packs being sequentially connected to the electric device via the electric circuit and connected in parallel; The electrical circuit comprises: A method for starting an electric operating machine including a plurality of external relays corresponding to the plurality of battery packs, the plurality of external relays opening and closing a circuit connecting the corresponding battery packs and the electric device, Before the battery pack is connected to the electric device, an external relay diagnosis process is performed to diagnose whether or not a contact of the external relay corresponding to the battery pack is stuck while an internal circuit of the battery pack is in an open state; In the external relay diagnosis process, A method for starting an electric work machine, comprising: operating the internal circuit of the battery pack to be diagnosed to an open state; operating the external relay corresponding to the battery pack to an open state; determining that the contacts of the external relay are stuck if the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than a threshold value; and determining that the contacts of the external relay are normal if the voltage between the external terminals of the positive and negative electrodes of the battery pack is lower than the threshold value.

11. Electrical equipment and an electrical circuit electrically connected to the electrical device; a plurality of battery packs each having positive and negative external terminals, the battery packs being sequentially connected to the electric device via the electric circuit and connected in parallel; The electrical circuit includes: a plurality of external relays corresponding to the plurality of battery packs, the plurality of external relays opening and closing a circuit connecting the corresponding battery pack and the electric device; The battery pack includes: A method for starting an electric operating machine having a discharge circuit that connects a negative external terminal side and a positive external terminal side in an internal circuit of the battery pack, the discharge circuit including a discharge resistor and a discharge relay connected in series, When the battery pack is connected to the electric device, a discharge relay diagnosis process is performed to diagnose whether or not a contact of the discharge relay of the battery pack is stuck; In the discharge relay diagnosis process, The external relay corresponding to the battery pack to be diagnosed is operated to a closed state, and the discharge relay of the battery pack is operated to an open state; A method for starting an electric work machine, which determines that the contacts of the discharge relay of the discharge circuit are stuck when the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than the threshold value and the voltage across the discharge circuit is equal to or lower than the threshold value, and determines that the contacts of the discharge relay of the discharge circuit are normal when the voltage between the external terminals of the positive and negative electrodes of the battery pack is equal to or higher than the threshold value and the voltage across the discharge circuit is higher than the threshold value.

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