Work machine

Abstract

To enable the supply of electric power suitable for driving the drive source installed in the work machine.SOLUTION: A work machine according to one embodiment of the present disclosure includes a main body, a lifting work unit, an inverter capable of converting between direct current and alternating current, a drive source that drives components included in the lifting work unit or the main body with the alternating current converted by the inverter, a power source that can supply direct current to the inverter, a power storage unit, a plurality of converters that are provided between the power storage unit and the inverter and control the charging and discharging of the power storage unit, and a control unit that is configured to instruct each of the plurality of converters to discharge the power storage unit based on the power supplied by the inverter to the drive source in order to drive the drive source in accordance with a received operation.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a work machine. [Background technology]

[0002] Conventionally, engine generators equipped with diesel engines or the like have been used as power sources for driving electric motors such as motors and pumps in cranes, etc. In such cranes, the electric power generated by the engine generator is supplied to the electric motors via a converter and an inverter.

[0003] Increasing the driving force of an electric motor requires increasing the capacity of the system that supplies power to the motor. Specifically, it is necessary to increase the output of the inverter that supplies power to the motor and also increase the current output from the converter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-11021 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in order to increase the current supplied to the electric motor in accordance with the driving force required by the crane or the like, it is necessary to design a converter that corresponds to the driving force of the crane or the like. Designing such a converter increases the burden on the developer and also increases the manufacturing load. In other words, in order to increase the current supplied to the electric motor, instead of designing a high-capacity converter, it is preferable to use multiple existing converters to reduce the burden on the developer and the manufacturing load.

[0006] According to one aspect of the present invention, by providing a plurality of converters, it is possible to supply electric power suitable for driving a drive source provided in a work machine. [Means for solving the problem]

[0007] A work machine according to one aspect of the present invention comprises a main body, a lifting work unit, an inverter capable of converting between direct current and alternating current, a drive source that drives components included in the lifting work unit or the main body with the alternating current converted by the inverter, a power source that can supply direct current to the inverter, a power storage unit, a plurality of converters that are provided between the power storage unit and the inverter and control the charging and discharging of the power storage unit, and a control unit that is configured to instruct each of the plurality of converters to discharge the power storage unit based on the power supplied by the inverter to the drive source, in order to drive the drive source in accordance with a received operation. [Effects of the Invention]

[0008] According to one aspect of the present invention, by providing a plurality of converters, it is possible to supply electric power suitable for driving a drive source provided in a work machine. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic view of a work machine according to a first embodiment. [Figure 2] 1 is a block diagram illustrating an example of a configuration related to the supply of electric power provided in a work machine according to a first embodiment. [Figure 3] FIG. 6 is a block diagram illustrating an example of the configuration relating to the supply of electric power provided in a work machine according to a second embodiment. [Figure 4] FIG. 11 is a block diagram illustrating an example of the configuration relating to the supply of electric power provided in a work machine according to a third embodiment. [Figure 5] FIG. 11 is a diagram illustrating the configuration of a database stored in a storage unit of a first battery converter according to a modified example of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The embodiments described below are illustrative and do not limit the invention. Not all features and combinations thereof in the embodiments of the present disclosure are necessarily essential to the invention. In addition, identical or corresponding components in each drawing are designated by identical or corresponding reference numerals, and redundant description may be omitted.

[0011] The work machine 100 according to the embodiment of the present disclosure is a gantry crane. The work machine 100 may be a crane other than a gantry crane, for example, an overhead crane, a jib crane, a crawler crane, an unloader, or the like. Furthermore, the work machine 100 may be an excavator, an asphalt finisher, a forklift, or the like.

[0012] (First embodiment) An overview of a work machine 100 according to this embodiment will be described with reference to Figure 1. Figure 1(A) is a schematic front view of the work machine 100 according to this embodiment, and Figure 1(B) is a schematic side view of the work machine 100 according to this embodiment. The work machine 100 shown in Figures 1(A) and 1(B) has a portal frame made up of pillars 40 and girders 41. Furthermore, in the work machine 100, multiple pillars 40 support the girders 41. The work machine 100 has wheels 42 attached to the lower ends of the pillars 40 and travels along rails 43. The direction perpendicular to the plane of Figure 1(A) and the left-right direction in Figure 1(B) correspond to the travel direction. A trolley 45 is mounted on the girders 41. A hoist 46 is mounted on the trolley 45. The work machine 100 has a main body made up of pillars 40, girders 41 (portal frame) and wheels 42, and a working section made up of a trolley 45, a hoist 46 and a hoisting working section (hanging tool 47 and wire).

[0013] A plurality of electric actuators provided on the work machine 100 drive components of the main body or operating unit. For example, a travel motor (an example of a drive source) 51 mounted on the portal frame drives the wheels 42. A traverse motor 52 (an example of a drive source) mounted on the trolley 45 moves the trolley 45 in the traverse direction. The left-right direction in FIG. 4(A) and the direction perpendicular to the paper surface in FIG. 4(B) correspond to the traverse direction. The hoist 46 includes a hoist motor 53, and the hoist motor (an example of a drive source) 53 hoists and reels out a wire having a suspending device 47, such as a hook, attached to the tip thereof. In this way, electric actuators such as the hoist motor 53, the traverse motor 52, and the travel motor 51 operate the suspending device 47, the trolley 45, and the wheels 42, respectively.

[0014] The work machine 100 is equipped with an engine power generating facility 60, a power conversion system 90, and a storage battery 70.

[0015] The engine power generation equipment 60 (an example of a power source) includes an engine 61 and a generator 62, and is configured so that the engine 61 can operate the generator 62 to supply electric power as a direct current. For example, the engine power generation equipment 60 supplies direct current to each of a first inverter 94, a second inverter 95, and a third inverter 96. Note that in this embodiment, an example in which electric power is supplied to each of the first inverter 94, the second inverter 95, and the third inverter 96 will be described. However, the destination of the electric power supplied by the engine power generation equipment 60 is not limited, and the engine power generation equipment 60 may be configured to supply electric power to at least one of the first inverter 94, the second inverter 95, and the third inverter 96, and to supply electric power from the storage battery 70 to the other inverter. Furthermore, the electric power supplied from the engine power generation equipment 60 is charged into the storage battery 70.

[0016] The power conversion system 90 converts the power flowing between the engine power generation equipment 60, the storage battery 70, the hoisting motor 53, the traverse motor 52, and the travel motor 51 according to the supply destination. The specific configuration of the power conversion system 90 will be described later.

[0017] Figure 2 is a block diagram illustrating an example of the configuration related to the supply of power provided in the work machine 100 according to this embodiment. As shown in Figure 2, the work machine 100 is equipped with a hoist motor 53, a traverse motor 52, a travel motor 51, an engine power generation facility 60, an engine converter 65, a storage battery 70, a power conversion system 90, a controller 30, an operation device 31, and an operation sensor 32.

[0018] The engine converter 65 receives the electric power generated by the engine power generation equipment 60 , converts it into direct current, and supplies it to the DC link 97 .

[0019] The storage battery 70 is an example of a power storage unit that can charge and discharge power, and may be, for example, a lithium ion battery or a lithium ion capacitor.

[0020] The power conversion system 90 includes a first inverter 94, a second inverter 95, a third inverter 96, a first battery converter 91, a second battery converter 92, and a third battery converter 93. These components are connected by a DC link 97. In this embodiment, the target voltage value of the DC link 97 is 680 V, but an appropriate target voltage value may be determined depending on the implementation.

[0021] The first inverter 94, the second inverter 95, and the third inverter 96 are capable of converting between DC and AC current.

[0022] For example, the first inverter 94 receives a DC link voltage stabilized to a target voltage from the DC link 97, converts it into AC power, and drives the traction motor 51.

[0023] For example, the second inverter 95 receives a DC link voltage stabilized to a target voltage from the DC link 97 , converts it into AC power, and drives the traverse motor 52 .

[0024] For example, the third inverter 96 receives a DC link voltage stabilized to a target voltage from the DC link 97 , converts it into AC power, and drives the hoist motor 53 .

[0025] The traveling motor 51 drives the wheels 42 included in the main body with the AC current converted by the first inverter 94. The traverse motor 52 drives the trolley 45 with the AC current converted by the second inverter 95. The hoisting motor 53 drives the hoisting tool 47 with the AC current converted by the third inverter 96.

[0026] The first battery converter 91, the second battery converter 92, and the third battery converter 93 are provided between the storage battery 70 and the first inverter 94, the second inverter 95, and the third inverter 96, respectively, and control the charging and discharging of the storage battery 70. In this embodiment, an example in which three battery converters 91 to 93 are provided will be described, but the number of battery converters is not limited, and may be determined according to the capacity required to drive the work machine 100. For example, the number of battery converters may be four or more, or may be two. The specific configurations of the first battery converter 91, the second battery converter 92, and the third battery converter 93 will be described later.

[0027] However, when a work machine is equipped with three or more battery converters, it becomes difficult for the battery converter to recognize all of the battery converters equipped in the work machine. For example, when there are two battery converters, it is easy to recognize the existence of other battery converters through mutual communication. In contrast, when three or more battery converters are equipped, it becomes difficult for the battery converter to grasp the number of battery converters equipped in the entire work machine 100, considering the possibility that battery converters may be added or removed. Therefore, in this embodiment, an example will be described in which the controller 30 that controls the entire work machine 100 recognizes the number of battery converters equipped in the work machine 100.

[0028] The controller (control device) 30 is a control device for controlling the work machine 100. For example, the controller 30 is mainly composed of a computer including a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), a non-volatile auxiliary storage device, various input / output interfaces, etc. The controller 30 reads programs from the non-volatile storage device, loads them into the volatile storage device, and has the CPU execute them to realize various functions.

[0029] The operating device 31 is an example of an electric operating device that an operator uses to operate each of the sling 47, the trolley 45, and the wheels 42.

[0030] The operation sensor 32 is configured to detect the operation content of the operator using the operation device 31. In this embodiment, the operation sensor 32 detects the operation direction and operation amount of the operation device 31 corresponding to each of the suspending tool 47, the trolley 45, and the wheel 42, and outputs the detected values ​​to the controller 30.

[0031] Controller 30 is configured to control first inverter 94, second inverter 95, and third inverter 96 in accordance with a signal input from operation sensor 32, causing each of suspending device 47, trolley 45, and wheels 42 to operate in accordance with the operation content. When an operator operates operation device 31, control signals are output according to the operation content and operation direction for operating suspending device 47, trolley 45, and wheels 42. In other words, even when controller 30 does not accept an operation from operation device 31, it can operate each of suspending device 47, trolley 45, and wheels 42 by outputting control signals to each of first inverter 94, second inverter 95, and third inverter 96.

[0032] [Controller function configuration] The controller 30 controls the entire working machine 100. For example, the controller 30 performs control to output a current command to each of the plurality of battery converters 91, 92, 93 to instruct the storage battery 70 to discharge, based on the power supplied by inverters 94, 95, 96 to at least one or more of the traveling motor 51, the traverse motor 52, and the hoisting motor 53, in order to drive at least one or more of the traveling motor 51, the traverse motor 52, and the hoisting motor 53 in accordance with an operation received by the operating device 31. Specifically, the controller 30 includes an operation receiving unit 301, an operation control unit 302, an acquisition unit 303, and a current distribution unit 304.

[0033] The controller 30 recognizes the number of battery converters 91, 92, 93 provided on the work machine 100 as part of the overall configuration of the work machine 100. Any method may be used to recognize the number of battery converters, and the number may be recognized through communication with each of the battery converters 91, 92, 93, or the number of battery converters provided on the work machine 100 may be stored in a memory unit (not shown) provided in the controller 30.

[0034] The operation receiving unit 301 receives an operation signal indicating the operation direction and operation amount for the operation device 31 via the operation sensor 32 .

[0035] Based on the operation signal received by the operation receiving unit 301, the operation control unit 302 generates control signals for operating the first inverter 94, the second inverter 95, and the third inverter 96 in response to the received operation signal, and outputs control commands to each of the first inverter 94, the second inverter 95, and the third inverter 96. A method for generating control commands corresponding to the operation amounts may be the same as a conventional method, and therefore a description thereof will be omitted.

[0036] The acquisition unit 303 acquires detection results from various sensors provided on the work machine 100. Furthermore, the acquisition unit 303 acquires from the first battery converter 91 a current command indicating the value of the current to be supplied to the DC link 97 of the work machine 100.

[0037] The current distribution unit 304 distributes the acquired current command to the battery converters 91 to 93, and outputs the distributed current command to each of the first battery converter 91, the second battery converter 92, and the third battery converter 93.

[0038] In this embodiment, the current distribution unit 304 distributes the current equally to the first battery converter 91, the second battery converter 92, and the third battery converter 93. In this embodiment, the current distribution unit 304 may distribute different current values ​​depending on the characteristics of the first battery converter 91, the second battery converter 92, and the third battery converter 93.

[0039] Furthermore, the current distribution unit 304 stores a current threshold value in advance. When distributing the current, the current distribution unit 304 determines whether the current value distributed to each of the first battery converter 91, the second battery converter 92, and the third battery converter 93 will be lower than the current threshold value. If the current distribution unit 304 determines that the current value to be distributed will be lower than the current threshold value, it outputs the acquired current command to the first battery converter 91 without distributing the current value. This control can improve the stability of the control.

[0040] The work machine 100 according to this embodiment lifts and lowers a load when the hoisting tool 47 is operated. The position where the load to be hoisted is installed and the position where the load is lowered are often determined in advance. That is, in the work machine 100, it is easy to estimate the timing for lifting and lowering. In other words, it is easy to determine the timing for starting the supply of power from the storage battery 70 and the timing for starting charging the storage battery 70 through regeneration, in accordance with the operation received from the operating device 31.

[0041] Furthermore, when autonomous control or semi-automatic control is performed on the work machine 100, the lifting speed and lowering speed of the suspended load are determined in advance. Also, the weight of the suspended load can often be known in advance. In other words, the current values ​​output from each of the first battery converter 91, the second battery converter 92, and the third battery converter 93 can often be estimated in advance.

[0042] Therefore, there is also a method in which, when the controller 30 receives an operation that is presumed to be the start of lifting or the start of lifting, it distributes a predetermined current command corresponding to the lifting operation or the lifting operation to each of the first battery converter 91, the second battery converter 92, and the third battery converter 93, and outputs the distributed current command. By performing this control, the lifting operation or the lifting operation can be performed quickly without the detected voltage value of the DC link 97 decreasing compared to an appropriate target voltage value.

[0043] The first battery converter 91 has a primary side connected to an external DC link 97 and a secondary side connected to the storage battery 70, and functions as a step-up / step-down converter to perform power conversion between the DC link 97 and the storage battery 70. Furthermore, the first battery converter 91 includes a voltage control unit 91A, a current control unit 91B, and an interface circuit 91C.

[0044] The interface circuit 91C is a circuit provided for transmitting and receiving signals to and from the controller 30.

[0045] The voltage control unit 91A generates a current command value that brings the voltage detection value of the DC link 97, detected by the voltage sensor, closer to a target voltage value (an example of a predetermined value). The voltage sensor may be provided at a position where it can detect the voltage of the DC link 97, and may be provided inside the first battery converter 91, for example.

[0046] The voltage control unit 91A includes, for example, an error detector and a PI (proportional-integral) controller, and the error detector detects a voltage error between a detected voltage value and a target voltage value, and the PI controller generates a current command value corresponding to the voltage error. The specific equation for calculating the current command value is similar to that used in conventional PI control, so a detailed explanation will be omitted. The voltage control unit 91A outputs the generated current command value to the controller 30 via the interface circuit 91C.

[0047] Then, interface circuit 91C outputs the current command value to controller 30, and then receives from controller 30 the current command value distributed to first battery converter 91. That is, voltage control unit 91A calculates a current command value that brings the voltage closer to the target value and outputs it to controller 30, and then current distribution unit 304 of controller 30 generates a current command value distributed to each of battery converters 91-93 and outputs it to each of battery converters 91-93 so that the combination of battery converters 91-93 achieves an output according to the input current command value. Then, each of the multiple battery converters 91-93 performs current control based on the distributed current command value.

[0048] The current control unit 91B generates a duty cycle command value so that the current detection value detected by the first current sensor approaches the current command value distributed to the first battery converter 91. The current control unit 91B includes an error detector and a PI controller, and detects the current error between the current detection value detected by the error detector and the current command value, and generates a current command value corresponding to the current error using the PI controller. The equation for calculating the duty cycle command value is the same as that of conventional PI control, so its explanation will be omitted. The first current sensor detects a current detection value corresponding to the current flowing through the first battery converter 91.

[0049] The second battery converter 92 has a primary side connected to an external DC link 97 and a secondary side connected to the storage battery 70, and functions as a step-up / step-down converter to perform power conversion between the DC link 97 and the storage battery 70. Furthermore, the second battery converter 92 includes a current control unit 92A and an interface circuit 92B.

[0050] The interface circuit 92B is a circuit provided for transmitting and receiving signals to and from the controller 30.

[0051] The current control unit 92A generates a duty cycle command value so that the current detection value detected by the second current sensor approaches the current command value distributed to the second battery converter 92. The second current sensor detects a current detection value corresponding to the current flowing through the second battery converter 92.

[0052] The third battery converter 93 has a primary side connected to an external DC link 97 and a secondary side connected to the storage battery 70, and functions as a step-up / step-down converter to perform power conversion between the DC link 97 and the storage battery 70. Furthermore, the third battery converter 93 includes a current control unit 93A and an interface circuit 93B.

[0053] The interface circuit 93B is a circuit provided for transmitting and receiving signals to and from the controller 30.

[0054] The current control unit 93A generates a duty cycle command value so that the current detection value detected by the third current sensor approaches the current command value distributed to the third battery converter 93. The third current sensor detects a current detection value corresponding to the current flowing through the third battery converter 93.

[0055] Each of the battery converters 91-93 according to this embodiment performs current control so as to approach a current command value. Current control has higher responsiveness than voltage control, in other words, by each of the battery converters 91-93 performing current control, it is possible to achieve improved responsiveness when the work machine 100 operates.

[0056] In this embodiment, by using a plurality of battery converters 91 to 93, it is possible to accommodate an increase in the capacity of the power supplied to the inverters 94 to 96 and the power charged into the storage battery .

[0057] Furthermore, in this embodiment, after the voltage control unit 91A of the first battery converter 91 calculates a current command value, the controller 30 controls the distribution of the current command to each of the battery converters 91-93. In other words, in this embodiment, the first battery converter 91, which calculates the current command value, does not need to know the overall configuration of the battery converters 91-93 provided inside the power conversion system 90; it is sufficient for the controller 30, which controls the entire work machine 100, to know the overall configuration of the battery converters 91-93. In other words, by setting the number of battery converters provided inside the power conversion system 90 in the controller 30, it is possible to add or remove battery converters to be installed in the power conversion system 90. Therefore, in the work machine 100 according to this embodiment, it is easy to adjust the number of battery converters depending on the site to which the work machine 100 is shipped.

[0058] (Second embodiment) In the above-described embodiment, an example has been described in which a plurality of battery converters 91 to 93 are connected to one storage battery 70. However, the above-described embodiment is not limited to the example in which a plurality of battery converters are connected to one storage battery. Therefore, in the second embodiment, an example will be described in which a plurality of storage batteries are provided and a battery converter is connected to each of the plurality of storage batteries.

[0059] Figure 3 is a block diagram illustrating the configuration related to the supply of power provided in a work machine 1300 according to this embodiment. In the work machine 1300 shown in Figure 3, the same components as those in the work machines of the above-described embodiments are assigned the same reference numerals, and their description will be omitted.

[0060] In the working machine 1300 according to this embodiment, a plurality of storage batteries are provided so as to correspond to each of a plurality of battery converters.

[0061] The work machine 1300 shown in Fig. 3 is equipped with a first storage battery 171, a second storage battery 172, and a third storage battery 173. The first storage battery 171, the second storage battery 172, and the third storage battery 173 are storage batteries that are capable of charging and discharging power, and for example, lithium ion batteries, lithium ion capacitors, etc. are used.

[0062] The first storage battery 171, the second storage battery 172, and the third storage battery 173 may have the same or different storage capacities and characteristics.

[0063] The first battery converter 91 controls the charging and discharging of the first storage battery 171. The second battery converter 92 controls the charging and discharging of the second storage battery 172. The third battery converter 93 controls the charging and discharging of the third storage battery 173.

[0064] The first battery converter 91, the second battery converter 92, and the third battery converter 93 are controlled in the same manner as in the above-described embodiment. Specifically, the voltage control unit 91A of the first battery converter 91 generates a current command value that brings the voltage detection value of the DC link 97, detected by the voltage sensor, closer to the target voltage value. Then, the current distribution unit 304 of the controller 30 distributes the generated current command value among the first battery converter 91, the second battery converter 92, and the third battery converter 93.

[0065] The current distribution unit 304 of the controller 30 according to this embodiment has a method of varying the output current value depending on one or more of the SOC and battery capacity of the storage batteries 171, 172, and 173 when distributing a current command value to each of the first battery converter 91, the second battery converter 92, and the third battery converter 93.

[0066] For this purpose, the controller 30 stores in advance the battery capacities of the first storage battery 171, the second storage battery 172, and the third storage battery 173. Then, the acquisition unit 303 of the controller 30 acquires the SOCs of the first storage battery 171, the second storage battery 172, and the third storage battery 173 from sensors provided in the first storage battery 171, the second storage battery 172, and the third storage battery 173. Then, the current distribution unit 304 generates a current command value for a storage battery having a smaller SOC or battery capacity than the other storage batteries, such that the current value to be output is smaller than that of the other storage batteries.

[0067] In this embodiment, the controller (an example of a control unit) 30 may perform processing to recognize the number of battery converters and storage batteries connected to the battery converters at a predetermined timing. As a result, when storage batteries and battery converters are added or removed, the controller 30 recognizes the number of storage batteries and battery converter batteries at that predetermined timing. Therefore, in the work machine 1300 according to this embodiment, it is easy to adjust the number of battery converters for storage batteries in accordance with the work site to which the work machine 1300 is shipped.

[0068] (Modification of the second embodiment) In the above-described embodiment, the battery converters 91 to 93 have the same characteristics. However, the above-described embodiment is not limited to the case where the battery converters 91 to 93 have the same characteristics. Therefore, in a modified example of the second embodiment, an example will be described in which the characteristics of the battery converters 91 to 93 are made different depending on the connected storage batteries 171 to 173.

[0069] The storage batteries 171 to 173 according to this modification have different characteristics. The difference in characteristics between the storage batteries 171 to 173 may be the battery capacity or the rated output.

[0070] Each of the battery converters 91 to 93 has a different maximum current that can be output depending on the connected storage batteries 171 to 173. For example, if the battery capacities of the second storage battery 172 and the third storage battery 173 are greater than that of the first storage battery 171, the maximum current that can be output by the second battery converter 92 and the third battery converter 93 (which control the second storage battery 172 and the third storage battery 173) is made greater than that of the first battery converter 91.

[0071] The maximum current that can be output by battery converters 91 to 93 according to this modification is varied depending on the characteristics of connected storage batteries 171 to 173. In other words, this modification makes it possible to supply power according to the characteristics of the connected storage batteries, thereby achieving improved stability.

[0072] (Third embodiment) In the above-described embodiment, an example has been described in which the controller 30 distributes a current command value, in other words, a current, to each of the plurality of battery converters 91 to 93. However, the above-described embodiment is not limited to a method in which the controller 30 distributes a current command value, in other words, a current, to each of the plurality of battery converters 91 to 93. Therefore, in the third embodiment, an example in which the first battery converter distributes a current command value will be described.

[0073] Figure 4 is a block diagram illustrating the configuration related to the supply of power provided in a work machine 1400 according to this embodiment. In the work machine 1400 shown in Figure 4, the same components as those in the work machines of the above-described embodiments are assigned the same reference numerals, and their explanation will be omitted.

[0074] The work machine 1400 shown in FIG. 4 is configured to perform processing differently from the work machines 100 and 1300 according to the above-described embodiments, and is equipped with a controller 130, a first battery converter 191, a second battery converter 192, and a third battery converter 193.

[0075] The controller 130 includes an operation reception unit 301 and an operation control unit 302. The processing by the operation reception unit 301 and the operation control unit 302 is the same as in the above-described embodiment, and therefore a description thereof will be omitted.

[0076] In this embodiment, the first battery converter 191 distributes the current command value, and outputs the distributed current command value to the second battery converter 192 and the third battery converter 193.

[0077] The first battery converter 191 includes a voltage control unit 191A, a current distribution unit 191D, a current control unit 191B, and an interface circuit 191C.

[0078] The interface circuit 191C is a circuit provided for transmitting and receiving signals between the controller 130, the second battery converter 192, and the third battery converter 193.

[0079] The voltage control unit 191A generates a current command value that brings the voltage detection value of the DC link 97, detected by the voltage sensor, closer to the target voltage value.

[0080] Current distribution unit 191D distributes the current command generated by voltage control unit 191A to battery converters 191-193, and outputs the distributed current command to current control unit 191B. Furthermore, current distribution unit 191D outputs the distributed current command to second battery converter 192 and third battery converter 193.

[0081] A memory unit (not shown) of the first battery converter 191 according to this embodiment stores the number of battery converters connected to the work machine 1400. The current distribution unit 191D then divides the current value included in the current command by the number of battery converters. As a result, the current distribution unit 191D generates a current command to be output to each of the battery converters 191-193. The number of battery converters may be set by an administrator or the like. This setting allows the current distribution unit 191D to recognize the number of battery converters provided on the work machine 1400.

[0082] The current control unit 191B generates a duty cycle command value so that the current detection value detected by the first current sensor approaches the current command value distributed to the first battery converter 91 by the current distribution unit 191D.

[0083] The second battery converter 192 includes a current control section 192A and an interface circuit 192B.

[0084] The interface circuit 192B is a circuit provided for transmitting and receiving signals between the controller 130, the first battery converter 191, and the third battery converter 193.

[0085] The current control unit 192A generates a duty cycle command value so that the current detection value detected by the second current sensor approaches the current command value distributed to the second battery converter 92.

[0086] The third battery converter 193 includes a current control unit 193A and an interface circuit 193B.

[0087] The interface circuit 193B is a circuit provided for transmitting and receiving signals between the controller 130, the first battery converter 191, and the second battery converter 192.

[0088] The current control unit 193A generates a duty cycle command value so that the current detection value detected by the third current sensor approaches the current command value distributed to the third battery converter 193.

[0089] Each of the battery converters 191-193 according to this embodiment performs current control so as to approach a current command value. Current control has higher responsiveness than voltage control, in other words, by each of the battery converters 191-193 performing current control, it is possible to achieve improved responsiveness when the work machine 1400 operates.

[0090] In the above-described embodiment, the controller 30 distributes the current command. In contrast to this, in the present embodiment, the current command is distributed within the first battery converter 191. Therefore, transmission and reception of information regarding the current command between the controller 130 and the first battery converter 191 is suppressed, thereby achieving improved responsiveness and improved control stability.

[0091] (Modification of the third embodiment) In the third embodiment, an example has been described in which the current distribution unit 191D distributes the current command generated by the voltage control unit 191A equally to the battery converters 191 to 193. However, the third embodiment is not limited to an example in which the current distribution unit 191D distributes the current command generated by the voltage control unit 191A equally to the battery converters 191 to 193. Therefore, in a modification of the third embodiment, an example will be described in which the current command is determined according to the SOC and battery capacity of the storage batteries 171 to 173. The configuration of this modification is the same as that of the third embodiment.

[0092] A database that associates the SOC and battery capacity of the storage battery connected to the work machine 1400 is stored in a storage unit (not shown) of the first battery converter 191 according to this embodiment. Fig. 5 is a diagram illustrating the configuration of the database stored in the storage unit of the first battery converter 191.

[0093] 5 stores the SOC and battery capacity of each of the first storage battery 171, the second storage battery 172, and the third storage battery 173 in association with each other. The battery capacity of each of the first storage battery 171, the second storage battery 172, and the third storage battery 173 is stored in advance. As shown in FIG. 5, the battery capacity of the first storage battery 171 is 100 [Wh], and the battery capacities of the second storage battery 172 and the third storage battery 173 are 300 [Wh]. In this way, in this modification, the battery capacities of the first storage battery 171, the second storage battery 172, and the third storage battery 173 are different from each other.

[0094] In this embodiment, the acquisition unit 303 acquires a signal indicating the SOC from each of the first storage battery 171, the second storage battery 172, and the third storage battery 173, and updates the database with the SOC indicated by the acquired signal. Note that this modification is not limited to an aspect in which a signal indicating the SOC is acquired from each of the first storage battery 171, the second storage battery 172, and the third storage battery 173, and information indicating the SOC may be acquired from each of the first storage battery 171, the second storage battery 172, and the third storage battery 173 via the controller 30.

[0095] The current distributor 191D distributes the current command based on the SOC and battery capacity of each of the first storage battery 171, the second storage battery 172, and the third storage battery 173.

[0096] Next, a specific method for distributing the current command will be described. Assume that the current command generated by the voltage control unit 191A is A.

[0097] Then, the current distribution unit 191D derives the current value of the first storage battery 171 from "A x coefficient K x (SOC of the first storage battery x battery capacity of the first storage battery) / (SOC of the first storage battery x battery capacity of the first storage battery + SOC of the second storage battery x battery capacity of the second storage battery + SOC of the third storage battery x battery capacity of the third storage battery) + offset Y." When A = 1000 A, coefficient K = 1, and offset Y = 0, a current value of 210.5 A output by the first storage battery 171 is derived.

[0098] Similarly, the current distribution unit 191D derives the current value of the first storage battery 171 from "A x coefficient K x (SOC of the second storage battery x battery capacity of the second storage battery) / (SOC of the first storage battery x battery capacity of the first storage battery + SOC of the second storage battery x battery capacity of the second storage battery + SOC of the third storage battery x battery capacity of the third storage battery) + offset Y." When A = 1000 A, coefficient K = 1, and offset Y = 0, a current value of 394.7 A output by the second storage battery 172 is derived.

[0099] Then, the current distribution unit 191D derives the current value of the third storage battery 173 from "A × coefficient K × (SOC of the third storage battery × battery capacity of the third storage battery) / (SOC of the first storage battery × battery capacity of the first storage battery + SOC of the second storage battery × battery capacity of the second storage battery + SOC of the third storage battery × battery capacity of the third storage battery) + offset Y." When A=1000 A, coefficient K=1, and offset Y=0, a current value of 394.7 A output by the first storage battery 171 is derived.

[0100] The current distributor 191D according to this modification is configured to distribute a current command so as to vary the current value output from each of the plurality of battery converters 191 to 193 based on the SOC and battery capacity of the plurality of storage batteries 171, 172, 173, and to output the current command, thereby instructing the plurality of storage batteries 171, 172, 173 to discharge. In this modification, an example has been described in which the current value is varied based on the SOC and battery capacity of the plurality of storage batteries 171, 172, 173, but the condition for varying the current value is not limited to a combination of SOC and battery capacity, and the distributed current value may also be varied based on the battery capacity, for example.

[0101] In this modification, the current value output from each of the plurality of battery converters 191 to 193 is varied based on the battery capacity of the storage batteries 171, 172, and 173. In other words, it is possible to output a current suited to the battery capacity, thereby preventing imbalances in the SOC of each of the storage batteries 171, 172, and 173, and enabling a stable supply of power.

[0102] For example, the battery capacity of the first storage battery 171 is 100 [Wh], and the battery capacities of the second storage battery 172 and the third storage battery 173 are 300 [Wh]. In this case, the current distribution unit 191D distributes current commands to each of the plurality of battery converters 191 to 193 so that the current values ​​output from the second storage battery 172 and the third storage battery 173 are larger than the current value output from the first storage battery 171.

[0103] Thereafter, the voltage control unit 191A may generate a current command with a different current value. When the change in the current value of the generated current command is smaller than a predetermined threshold value compared to the previously generated current command, the current distribution unit 191D changes the current command to be output to the current control unit 191B of the first battery converter 191 so as to adjust the current value output from the first storage battery 171, and suppresses changes to the current commands to be output to the second battery converter 192 and the third battery converter 193. In other words, even when multiple battery converters are provided, it is only necessary to adjust the current command in the first battery converter 191 when the current value to be adjusted is small, thereby suppressing a decrease in responsiveness due to communication between the battery converters and achieving improved stability.

[0104] Furthermore, in this modification, the second battery converter 192 and the third battery converter 193 are capable of outputting a larger amount of power than the first battery converter 191, while the first battery converter 191 is capable of outputting a smaller amount of power than the second battery converter 192 and the third battery converter 193. In other words, the first battery converter 191 allows for more precise current adjustment than the second battery converter 192 and the third battery converter 193. By being provided with such a configuration, the work machine 1400 according to this modification is able to output a large amount of current using the second battery converter 192 and the third battery converter 193, and by allowing the first battery converter 191 to make precise adjustments to the current value, precise current control is possible even when a large amount of power is output, thereby achieving improved stability.

[0105] <effect> In the above-described embodiment and modified examples, a work machine is provided with multiple converters, and each of the multiple converters is configured to be instructed to discharge from the storage battery, so the power supply can be shared among the multiple converters. In other words, even when a large amount of power is required, there is no need to prepare a converter with special specifications for supplying a large amount of power, which reduces the design and manufacturing burdens.

[0106] The preferred embodiments and modifications of the present disclosure have been described above. However, the invention according to the present disclosure is not limited to the above-described embodiments. Various modifications, substitutions, etc. may be applied to the above-described embodiments without departing from the scope of the invention according to the present disclosure. Furthermore, each of the features described with reference to the above-described embodiments may be combined as appropriate unless technically inconsistent. [Explanation of symbols]

[0107] 100, 1300, 1400 Work Machine 45 Trolley 46 Windlass 47 Hanging Device 51 Drive motor 52 Traverse motor 53 Winding motor 60 Engine power generation equipment 65 Engine Converter 70 Storage battery 171 First Battery 172 Second Battery 173 Third Battery 91, 191 First battery converter 91A, 191A voltage control section 91B, 191B Current control section 91C, 191C interface circuit 191D Current distribution section 92, 192 Second Battery Converter 92A, 192A Current control section 92B, 192B interface circuit 93 Third Battery Converter 93A, 193A Current control section 93B, 193B interface circuit 94 First inverter 95 Second inverter 96 Third Inverter 97 DC Link 30 Controllers 301 Operation reception section 302 Motion control section 303 Acquisition Department 304 Current distribution section 31 Operating device 32 Operation sensor

Claims

1. a main body; A lifting work section; an inverter capable of converting between direct current and alternating current; a drive source that drives a component included in the lifting work unit or the main body unit using the AC current converted by the inverter; and a power source capable of supplying a direct current to the inverter; A power storage unit; a plurality of converters provided between the power storage unit and the inverter to control charging and discharging of the power storage unit; a control unit configured to instruct each of the plurality of converters to discharge the power storage unit based on power supplied from the inverter to the driving source in order to drive the driving source in accordance with the received operation; A work machine comprising:

2. a plurality of the power storage units are provided corresponding to the plurality of converters, 2. The work machine according to claim 1.

3. each of the plurality of converters has a different maximum output current based on characteristics of the power storage unit connected thereto; 3. The work machine according to claim 2.

4. each of the plurality of power storage units has a different battery capacity; the control unit is configured to vary a current value output from each of the plurality of converters based on battery capacities of the plurality of power storage units, and to instruct the power storage units to discharge.

4. The work machine according to claim 3.

5. Three or more of the converters are provided, one of the plurality of converters has a voltage control unit that detects a voltage between the converter and the inverter and generates a current command value that indicates a current value output from the plurality of converters so as to make the detected voltage approach a predetermined voltage value; the control unit distributes the calculated current command value to each of the plurality of converters; Each of the plurality of converters is configured to perform current control based on the distributed current command value. A work machine according to any one of claims 1 to 4.

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