JP2015070690A - Device and method for charging power storage device for driving work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method for charging a power storage device for a work machine capable of securing the safety and shortening a charging time.SOLUTION: Provided is a device for charging a power storage device for a work machine, comprising one accumulator battery group 32 configured by series-connecting a plurality of accumulator batteries 31, and the other accumulator battery group 33 connected in parallel to the one accumulator battery group 32. The device for charging a power storage device for a work machine comprises: switches 36 and 37 switching an external power supply 100 and each accumulator battery group to an electrically-connected state or a disconnected state; voltage sensors 38 and 39 respectively detecting a voltage of each accumulator battery group; and a controller 41, in a case where it is determined that a voltage difference occurs between the one accumulator battery group 32 and the other accumulator battery group 33 on the basis of the detection value from each voltage sensor, controlling the switch of the low-voltage side accumulator battery group to a closing state and controlling the switch of the high-voltage side accumulator battery group to an opening state, and in a case where it is determined that a voltage of the one accumulator battery group 32 is substantially the same as a voltage of the other accumulator battery group 33, controlling each switch to the closing state.

Description

  The present invention relates to a charging device and a charging method for a power storage device for driving a work machine.

  Some work machines employ an electric drive instead of an internal combustion engine as a power source for driving a hydraulic pump, and are equipped with a power storage device that supplies electric power to the electric motor. In order to enable long-time operation, the power storage device of the electrically driven work machine includes a plurality of storage battery groups configured by connecting a plurality of storage batteries in series, and connects each storage battery group in parallel. The power is switched and supplied to the motor. In a power storage device provided with such a plurality of storage battery groups, each storage battery group is generally switched and charged in order, and therefore a long charging time is required. Therefore, in order to shorten the charging time, a method is conceivable in which a plurality of storage battery groups are connected in parallel and charged simultaneously.

  As a method of charging by connecting multiple storage batteries (groups) in parallel, efficiency is easily achieved by a single charging operation from a low-voltage power source without the need for cost and labor and without using a special device such as a buck-boost chopper. In order to charge well, all the storage batteries are connected in parallel by the switch device, so that a current flows from the high-voltage storage battery to the low-voltage storage battery, and the voltage of the plurality of storage batteries becomes a predetermined voltage after the voltage becomes substantially the same. Some start charging after the passage of time (see Patent Document 1).

JP 2006-67683 A (paragraph 0023, FIG. 3)

  In the invention described in Patent Document 1 described above, the current is passed from the high-voltage storage battery to the low-voltage storage battery by connecting the storage batteries in parallel, and the plurality of storage batteries have a predetermined voltage after the voltages become substantially the same. Since charging starts after a certain period of time, charging is not performed until the voltage of the plurality of storage batteries becomes substantially the same voltage, and it takes a lot of time to start charging. I must.

  Moreover, in the invention described in Patent Document 1, in order to flow current from a high-voltage storage battery to a low-voltage storage battery by connecting the storage batteries in parallel, the voltages of the plurality of storage batteries are set to substantially the same voltage. When the voltage between the two is greatly different, a large current flows from the high-voltage storage battery to the low-voltage storage battery, the connection wiring and the storage battery become high temperature, and a safety problem may occur.

  The present invention has been made based on the above-described matters, and an object of the present invention is to provide a charging device and a charging method for a power storage device for a working machine that can ensure safety and shorten the charging time. Is.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided one storage battery group configured by connecting a plurality of storage batteries that are charged by power supply from an external power supply in series, and the one storage battery group connected in parallel. A storage device for a working machine comprising the other storage battery group, wherein the external power source and each of the storage battery groups are switched between a state of being electrically connected and a state of being shut off, and each of the storage batteries. When it is determined that there is a voltage difference between the one storage battery group and the other storage battery group based on the voltage sensor that detects the voltage of each group and the detection value from each voltage sensor, The switch of the low-voltage side storage battery group is closed and the switch of the high-voltage side storage battery group is controlled to be in the open state, and it is determined that the one storage battery group and the other storage battery group have substantially the same voltage. If, before Each switch characterized by comprising a controller for controlling a closed state.

  In a second aspect based on the first aspect, the controller calculates an absolute value of a difference between detection values from the voltage sensors, compares the calculation result with a prestored threshold value, and calculates the calculation result. When the result is smaller than the threshold value, it is determined that the one storage battery group and the other storage battery group have substantially the same voltage, and otherwise, between the one storage battery group and the other storage battery group It is characterized in that it is determined that there is a voltage difference.

  Furthermore, the third aspect of the invention relates to one storage battery group configured by connecting a plurality of storage batteries charged by power supply from an external power supply in series, and the other storage battery group connected in parallel to the one storage battery group. A method for charging a power storage device for a working machine comprising: a step of detecting a voltage of each of the storage battery groups with a voltage sensor; and based on a detection value of the voltage sensor, the one storage battery group and the other storage battery group A procedure for determining whether there is a voltage difference with the storage battery group or whether the one storage battery group and the other storage battery group have substantially the same voltage, and the one storage battery group in the determining procedure; When it is determined that a voltage difference has occurred with the other storage battery group, the storage battery group on the high voltage side and the external power supply are electrically disconnected, and the storage battery group on the low voltage side is connected with the external power supply. Connect electrically to charge When it is determined that the one storage battery group and the other storage battery group have substantially the same voltage in the procedure and the determination procedure, the storage battery groups are electrically connected to the external power source and charged. And a procedure.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the determining step is performed by comparing the step of calculating the absolute value of the difference between the detected values from the voltage sensors and the calculation result with a previously stored threshold value. And determining that the voltage between the one storage battery group and the other storage battery group is substantially the same when the calculation result is smaller than the threshold, and otherwise, the one storage battery It is a procedure for judging that a voltage difference is generated between the group and the other storage battery group.

  According to the present invention, when a voltage difference is generated between one storage battery group and the other storage battery group, only the storage battery group on the low voltage side is charged in advance, and one storage battery group and the other storage battery group are charged. Since the storage battery groups connected in parallel are charged at the same time after the voltage becomes substantially the same voltage, a large current does not flow from the storage battery group on the high voltage side to the storage battery group on the low voltage side, ensuring safety. In addition, the charging time can be shortened.

1 is a side view showing a working machine to which an embodiment of a charging device for a power storage device for driving a working machine of the present invention is applied. It is a top view which shows the working machine which applied one Embodiment of the charging device of the electrical storage apparatus for working machine drive of this invention shown in FIG. It is a block diagram which shows one Embodiment of the charging device of the electrical storage apparatus for working machine drive of this invention with an electrical storage apparatus. It is a flowchart figure which shows an example of the charging method in one Embodiment of the charging device of the electrical storage apparatus for working machine drive of this invention shown in FIG. It is a schematic diagram which shows transition of the charging rate of each storage battery group in an example of the charging method in one Embodiment of the charging device of the electrical storage apparatus for working machine drive of this invention shown in FIG. 3, (a) is a low voltage side The figure which shows the state which charges only the storage battery group in advance, (b) is a figure which shows the state which charges each storage battery group used as the substantially the same voltage simultaneously.

Hereinafter, a battery-type hydraulic excavator will be described as an example of a work machine, and an embodiment of a charging device and a charging method for a power storage device for driving a work machine according to the present invention will be described with reference to the drawings.
The present invention can be applied to a work machine including a power storage device as a power source of an electric motor, and is not limited to a battery-type hydraulic excavator. For example, the present invention can also be applied to a so-called hybrid work machine in which a work machine such as a battery-type forklift that uses a power storage device as a main power source or an auxiliary power of an internal combustion engine that uses an electric motor.

  1 to 3 show an embodiment of a charging device for a power storage device for driving a work machine according to the present invention. FIG. 1 shows an embodiment of a charging device for a power storage device for driving a work machine according to the present invention. 2 is a side view showing the working machine, FIG. 2 is a plan view showing the working machine to which an embodiment of the charging device for the power storage device for driving the working machine of the present invention shown in FIG. 1 is applied, and FIG. 3 is the working machine of the present invention. It is a block diagram which shows one Embodiment of the charging device of the electrical storage apparatus for a drive with an electrical storage apparatus. In FIG. 2, the work front 4 shown in FIG. 1 is partially omitted.

  In FIG. 1, a battery-type hydraulic excavator 1 includes a traveling body 2, a revolving body 3 that is turnably mounted on the traveling body 2, and a work front 4 that is installed on the front side of the revolving body 3 so as to be able to be raised and lowered. ing.

  The traveling body 2 is rotatably supported by a track frame 5, a rear end (right side in FIG. 1) of the track frame 5, and is driven by a traveling electric motor (not shown). An idler wheel 7 rotatably supported at the front end (left side in FIG. 1) and a crawler belt 8 wound around the drive wheel 6 and the idler wheel 7 are provided.

  The work front 4 includes a boom 9 attached to the revolving body 3 so as to be able to be lifted and lowered by a boom cylinder 9a, an arm 10 attached to the boom 9 so as to be rotatable by an arm cylinder 10a, and a arm 10 that can be turned by a bucket cylinder 11a. And a bucket 11 provided at the tip.

  As shown in FIGS. 1 and 2, the revolving unit 3 is provided on a revolving frame 12 that can be revolved on the traveling unit 2 and on the front side of the revolving frame 12 (left side in FIGS. 1 and 2). A cab 13 for operation, a counterweight 14 provided at the rear end (right side in FIGS. 1 and 2) of the revolving frame 12, and provided between the cab 13 and the counterweight 14 to store the power storage device 30. The power storage device storage portion 15, the hydraulic pump storage portion 16 provided on the right side of the cab 13 (upper side in FIG. 2) and storing the hydraulic pump 21 and the hydraulic motor 22 for the hydraulic pump, the cab 13 and the hydraulic pump storage. And a turning mechanism 17 having a turning electric motor 23.

  The battery-type hydraulic excavator 1 drives the hydraulic pump 21 with a hydraulic pump electric motor 22 to supply pressure oil to the boom cylinder 9a, the arm cylinder 10a, and the bucket cylinder 11a. Each bucket 11 is driven. Further, the turning body 3 is turned by the turning electric motor 23, and the traveling body 2 is moved forward and backward by the running electric motor (not shown). The hydraulic pump electric motor 22, the turning electric motor 23, and the traveling electric motor are supplied with electric power from the power storage device 30.

  Next, an embodiment of a charging device for a power storage device for driving a work machine according to the present invention will be described with reference to FIG. In FIG. 3, the same reference numerals as those shown in FIGS. 1 and 2 are the same parts, and detailed description thereof is omitted.

  The charging device illustrated in FIG. 3 charges the power storage device 30 by supplying power from the external power supply 100. Power storage device 30 is electrically connected to external power supply 100 via connector 25 during charging.

  The power storage device 30 includes a first storage battery group 32 configured by connecting a plurality (for example, five in FIG. 3) of storage batteries 31 in series, and a plurality of (for example, five in FIG. 3) storage batteries 31 in series. The second storage battery group 33 is connected and configured, and the first storage battery group 32 and the second storage battery group 33 are connected in parallel.

  The power storage device 30 is electrically connected to the vehicle body drive system 24 including the hydraulic pump electric motor 22 (see FIG. 2), the turning electric motor 23 (see FIG. 2), and the traveling electric motor (not shown). The first storage battery group 32 and the second storage battery group 33 are switched to supply electric power to the electric motors 22 and 23 of the vehicle body drive system 24.

  A first switch 36 is connected in series to the first storage battery group 32. The first switch 36 switches the first storage battery group 32 and the external power source 100 between an electrically connected state and a disconnected state. A second switch 37 is connected in series to the second storage battery group 33. The second switch 37 switches the second storage battery group 33 and the external power source 100 between an electrically connected state and a disconnected state.

  A first voltage sensor 38 that detects the voltage of the first storage battery group 32 is connected to both ends of the first storage battery group 32. A second voltage sensor 39 that detects the voltage of the second storage battery group 33 is connected to both ends of the second storage battery group 33. Each of the first voltage sensor 38 and the second voltage sensor 39 is connected to the controller 41 and outputs detection signals V1 and V2 corresponding to the detected voltage to the controller 41.

  The controller 41 includes an input unit 42 that inputs the detection signals V1 and V2 of the voltage sensors 38 and 39, a storage unit 43 that stores a threshold value and a set value in advance, a calculation unit 44 that performs predetermined calculation and comparison determination, An output unit 45 that outputs an open command signal or a close command signal to each of the switches 36 and 37 based on the determination of the calculation unit 44 is provided.

  In the storage unit 43, there is a voltage difference between the first storage battery group 32 and the second storage battery group 33, or the first storage battery group 32 and the second storage battery group 33 have substantially the same voltage. In order to determine whether or not there is, a threshold value Vt to be compared with a calculation result | δV | to be described later of the calculation unit 44 is stored. Further, in order to determine whether or not the first storage battery group 32 and the second storage battery group 33 that are being charged have reached a fully charged state, comparison is made with the detection signals V1 and V2 from the voltage sensors 38 and 39. A set value Vc is stored.

  As will be described later, the calculation unit 44 calculates the absolute value | δV | (= | V1−V2 |) of the difference between the detection value V1 from the first voltage sensor 38 and the detection value V2 from the second voltage sensor 39. By calculating and comparing the calculation result | δV | with the threshold value Vt stored in the storage unit 43, there is a voltage difference between the first storage battery group 32 and the second storage battery group 33, or the first It is determined whether the first storage battery group 32 and the second storage battery group 33 have substantially the same voltage. When it is determined that there is a voltage difference between the first storage battery group 32 and the second storage battery group 33, only the storage battery group on the low voltage side is charged to charge only the storage battery group on the low voltage side. Outputs a switch close command signal. On the other hand, when it is determined that the first storage battery group 32 and the second storage battery group 33 have substantially the same voltage, the first storage battery group 32 and the second storage battery group 33 connected in parallel are simultaneously connected. In order to charge, the close command signal of each switch 36 and 37 is output.

  The calculation unit 44 also detects the detected values V1 and V2 from the voltage sensors 38 and 39 and the set value Vc stored in the storage unit 43 during simultaneous charging of the first storage battery group 32 and the second storage battery group 33. Are compared to determine whether or not the first storage battery group 32 and the second storage battery group 33 have reached a fully charged state. When it is determined that the fully charged state is reached, an open command signal for each of the switches 36 and 37 is output.

  The output unit 45 receives the opening command signal or the closing command signal for the first switch 36 from the calculating unit 44 as the first switch 36, and the opening command signal or the closing command signal for the second switch 37 from the calculating unit 44. Output to the second switch 37.

Next, a charging method in an embodiment of a charging device for a power storage device for driving a work machine according to the present invention will be described with reference to FIGS.
FIG. 4 is a flowchart showing an example of a charging method in the embodiment of the charging device for the power storage device for working machine drive of the present invention shown in FIG. 3, and FIG. 5 is the power storage device for driving the work machine of the present invention shown in FIG. It is a schematic diagram which shows transition of the charging rate of each storage battery group in an example of the charging method in one embodiment of this charging device, (a) shows the state of charging only the storage battery group on the low voltage side in advance. FIG. 4B is a diagram illustrating a state in which the storage battery groups having substantially the same voltage are charged simultaneously. In FIG. 5, the hatched area indicates the storage rate of the storage battery group, the arrow indicates the increase in the storage rate, and the broken line arrow indicates power supply to the storage battery group. 4 and FIG. 5, the same reference numerals as those shown in FIG. 1 to FIG. 3 are the same parts, and detailed description thereof will be omitted.

  First, the power storage state of the power storage device 30 configured as described above will be described. Since the power storage device 30 shown in FIG. 3 switches the first storage battery group 32 and the second storage battery group 33 and supplies power to the vehicle body drive system 24, the first storage battery group 32 and the second storage battery The group 33 generally differs greatly in the remaining amount of electricity depending on the usage status. Therefore, the voltage of the 1st storage battery group 32 and the 2nd storage battery group 33 is also greatly different according to the electrical storage residual amount.

  Next, a charging method in an embodiment of the charging device for the power storage device for driving a work machine according to the present invention will be described. In order to charge this power storage device 30, external power supply 100 is connected to the charging device shown in FIG. 3 via connector 25, and a switch (not shown) for instructing the start of charging is operated. As a result, the controller 41 starts charging control of the first storage battery group 32 and the second storage battery group 33.

  In FIG. 4, the controller 41 outputs an open command signal to both the first switch 36 and the second switch 37 shown in FIG. 3 (step S1). Accordingly, the first switch 36 and the second switch 37 are controlled to be in the open state, and the first storage battery group 32 and the second storage battery group 33 are electrically disconnected from the external power source 100.

  Next, the voltage detection signal V1 of the first battery group 32 detected by the first voltage sensor 38 shown in FIG. 3 and the voltage of the second battery group 33 detected by the second voltage sensor 39 are detected. Each of the signals V2 is captured (step S2).

  Next, the controller 41 determines whether or not the first storage battery group 32 and the second storage battery group 33 have substantially the same voltage (step S3). Specifically, the absolute value | δV | (= | V1−V2 |) of the difference between the detection signal V1 from the first voltage sensor 38 and the detection signal V2 from the second voltage sensor 39 is calculated, and this calculation is performed. Judgment is made based on whether or not the result | δV | is smaller than the threshold value Vt stored in advance in the storage unit 43 shown in FIG. If the calculation result | δV | is smaller than the threshold value Vt, it is determined that the first storage battery group 32 and the second storage battery group 33 have substantially the same voltage, and the process proceeds to step S16. It is determined that there is a voltage difference between the first storage battery group 32 and the second storage battery group 33, and the process proceeds to step S4.

  When the power storage device 30 is in the above-described power storage state, that is, when the voltages of the first storage battery group 32 and the second storage battery group 33 are greatly different, a detection signal from the first voltage sensor 38 in step S3. It is determined that the absolute value | δV | of the difference between V1 and the detection signal V2 from the second voltage sensor 39 is equal to or greater than the threshold value Vt (NO), and the first storage battery group 32 is lower than the second storage battery group 33. It is determined whether or not it is a voltage (step S4). Specifically, determination is made based on whether or not the detection signal V1 from the first voltage sensor 38 is smaller than the detection signal V2 from the second voltage sensor 39. When the detection signal V1 from the first voltage sensor 38 is smaller than the detection signal V2 from the second voltage sensor 39, it is determined that the first storage battery group 32 has a lower voltage than the second storage battery group 33. The process proceeds to step S5. Otherwise, it is determined that the second storage battery group 33 has a lower voltage than the first storage battery group 32, and the process proceeds to step S12.

  In step S4, when the controller 41 determines that the detection signal V1 from the first voltage sensor 38 is smaller than the detection signal V2 from the second voltage sensor 39 (YES), the first storage battery group 32 is in the second state. It is determined that the voltage is lower than that of the storage battery group 33, and a close command signal is output to the first switch 36 (step S5). As a result, the first switch 36 is controlled to be closed, and the first storage battery group 32 is electrically connected to the external power source 100. That is, as shown in FIG. 5A, only the first storage battery group 32 on the low voltage side is charged in advance. At this time, the controller 41 controls the external power supply 100 so as to obtain a charging current corresponding to the case where only one storage battery group is charged.

  Thereafter, the charging rate of the first storage battery group 32 increases, and the voltage also increases according to the charging rate. During charging of the first storage battery group 32, the controller 41 takes in the detection signal V1 from the first voltage sensor 38 and the detection signal V2 from the second voltage sensor 39, respectively (step S6). It is determined whether or not the storage battery group 32 and the second storage battery group 33 have substantially the same voltage (step S7). Specifically, as in step S3, the absolute value | δV | of the difference between the detection signal V1 and the detection signal V2 is calculated, and whether or not the calculation result | δV | is smaller than the threshold value Vt is determined.

  In step S7, when the voltage of the first storage battery group 32 has not increased until it becomes substantially the same as the voltage of the second storage battery group 33, the controller 41 determines that the calculation result | δV | is equal to or greater than the threshold value Vt (NO ), That is, it is determined that there is a voltage difference between the first storage battery group 32 and the second storage battery group 33, the process returns to step S6, and the above-described procedure is repeated. In other words, charging of only the first storage battery group 32 is continued until the voltage of the first storage battery group 32 on the low voltage side becomes substantially the same as the voltage of the second storage battery group 33 on the high voltage side.

  Thereafter, when the voltage of the first storage battery group 32 on the low voltage side rises and becomes substantially the same as the voltage of the second storage battery group 33 on the high voltage side, the controller 41 determines that the calculation result | δV | It determines with it being smaller than the threshold value Vt (YES), and outputs a close command signal to the 2nd switch 37 (step S8). Accordingly, the second switch 37 is controlled to be closed, and the first storage battery group 32 and the second storage battery group 33 are electrically connected to the external power source 100, respectively. That is, as shown in FIG. 5B, the switches 36 and 37 are closed, and the first storage battery group 32 and the second storage battery group 33 connected in parallel are simultaneously charged.

  At this time, since the storage battery groups 32 and 33 have substantially the same voltage, a large current does not flow from the high-voltage storage battery group to the low-voltage storage battery group during charging. During this charging, the controller 41 controls the external power supply 100 so as to obtain a charging current corresponding to the case where both the storage battery groups 32 and 33 are charged.

  Next, in a state where both the storage battery groups 32 and 33 are charged at the same time, the controller 41 takes in the detection signal V1 from the first voltage sensor 38 and the detection signal V2 from the second voltage sensor 39 (steps). S9), it is determined whether or not the first storage battery group 32 and the second storage battery group 33 have reached full charge (step S10). Specifically, the determination is made based on whether or not the detection signals V1 and V2 from the voltage sensors 38 and 39 are larger than a set value Vc stored in the storage unit 43 in advance.

  In step S10, when the controller 41 determines that the detection signals V1 and V2 from the voltage sensors 38 and 39 are equal to or lower than the set value Vc (NO), the first storage battery group 32 and the second storage battery group 33 are It is determined that charging is insufficient, and the process returns to step 9 to repeat the above-described procedure. In other words, simultaneous charging of the first storage battery group 32 and the second storage battery group 33 connected in parallel is continued until the first storage battery group 32 and the second storage battery group 33 reach a fully charged state.

  On the other hand, in step S10, when the controller 41 determines that the detection signals V1 and V2 from the voltage sensors 38 and 39 are larger than the set value Vc (YES), both the storage battery groups 32 and 33 have reached a fully charged state. Is determined, an open command signal is output to each of the first switch 36 and the second switch 37 (step S11), and the charging control is terminated. As a result, the first switch 36 and the second switch 37 are controlled to be in the open state, and the first storage battery group 32 and the second storage battery group 33 are electrically disconnected from the external power source 100, respectively.

  In step S 4, when the second storage battery group 33 has a lower voltage than the first storage battery group 32, the controller 41 indicates that the detection signal V 1 from the first voltage sensor 38 is output from the second voltage sensor 39. It determines with it being larger than the detection signal V2 (NO), and outputs a close command signal to the 2nd switch 37 (step S12). As a result, the second switch 37 is controlled to be in a closed state, and the second storage battery group 33 is in a state of being electrically connected to the external power source 100. That is, only the second storage battery group 33 on the low voltage side is charged in advance.

  Next, the controller 41 detects from the voltage sensors 38 and 39 while the second storage battery group 32 is being charged, as in the case where only the first storage battery group 32 is charged (steps S6 and S7). Each of the signals V1 and V2 is captured (step S13), and it is determined whether or not the first storage battery group 32 and the second storage battery group 33 have substantially the same voltage (step S14).

  The controller 41 determines that the calculation result | δV | is greater than or equal to the threshold value Vt in step S14 until the voltage of the second storage battery group 33 on the low voltage side becomes substantially the same as the voltage of the first storage battery group 32 on the high voltage side. It determines with (NO), returns to step S13, and repeats the procedure mentioned above. That is, the charged state of only the second storage battery group 33 is continued.

  When the voltage of the second storage battery group 33 becomes substantially the same as the voltage of the first storage battery group 32 by charging only the second storage battery group 33, the controller 41 determines that the calculation result | δV | is smaller than the threshold value Vt (YES). (Step S14), and a close command signal is output to the first switch 36 (step S15). As a result, the first switch 36 is controlled to be closed, and the storage battery groups 32 and 33 are electrically connected to the external power source 100, respectively. That is, the first storage battery group 32 and the second storage battery group 33 connected in parallel are charged simultaneously.

  Next, the controller 41 ends the charging control after executing the procedure of Steps S9 to S11 in the same manner as described above in the state where both the storage battery groups 32 and 33 are charged simultaneously.

  Further, in step S3, when the power storage device 30 is different from the power storage state described above, when the first storage battery group 32 and the second storage battery group 33 before charging have substantially the same voltage, the controller 41 calculates It is determined that the result | δV | is smaller than the threshold value Vt (YES), and a close command signal is output to each of the first switch 36 and the second switch 37 (step S16). As a result, the first switch 36 and the second switch 37 are controlled to be closed, and the first storage battery group 32 and the second storage battery group 33 connected in parallel are charged simultaneously.

  Next, the controller 41 ends the charging control after executing the procedure of Steps S9 to S11 in the same manner as described above in the state where both the storage battery groups 32 and 33 are charged simultaneously.

  As described above, according to the embodiment of the charging device and the charging method for the power storage device for driving a work machine of the present invention, between one storage battery group 32 (33) and the other storage battery group 33 (32). When there is a voltage difference, only the low-voltage storage battery group is charged in advance, and one of the storage battery groups 32 (33) and the other storage battery group 33 (32) become substantially the same voltage in parallel. Since the connected storage battery groups 32 and 33 are simultaneously charged, a large current does not flow into the storage battery group on the low voltage side from the storage battery group on the high voltage side, and safety can be ensured, and charging time can be reduced. Shortening can be achieved.

  In the above-described embodiment, the first voltage sensor 38 and the second voltage are used to determine whether or not the first storage battery group 32 and the second storage battery group 33 have reached the fully charged state. Although an example in which the detection signals V1 and V2 from the sensor 39 are determined based on whether or not the detection signals V1 and V2 are larger than the set value Vc stored in advance in the storage unit 43 is shown, the charging of the first storage battery group 32 and the second storage battery group 33 is performed. It is also possible to determine whether or not the first storage battery group 32 and the second storage battery group 33 have reached a fully charged state based on the current and a preset value stored in the storage unit 43. In this case, current sensors for detecting the current values of the storage battery groups 32 and 33 are connected in series to the storage battery groups 32 and 33, respectively.

  Moreover, in embodiment mentioned above, although the case where the two storage battery groups 32 and 33 were connected in parallel was demonstrated to the example, it is applicable also when three or more storage battery groups are connected in parallel. In this case, the controller 41 precedes and simultaneously charges the storage battery group having the lowest voltage and the storage battery group having substantially the same voltage as the lowest voltage storage battery group. Thereafter, the storage battery group having substantially the same voltage as the voltage of the storage battery group increased by charging is further connected to an external power source and simultaneously charged. Further, this procedure is repeated until all the storage battery groups have substantially the same voltage. As a result, the same effects as those of the above-described embodiment can be obtained.

1 Battery-powered excavator (work machine)
30 power storage device 31 storage battery 32 first storage battery group 33 second storage battery group 36 first switch 37 second switch 38 first voltage sensor 39 second voltage sensor 41 controller 100 external power source

Claims (4)

A power storage device for a working machine comprising one storage battery group configured by connecting a plurality of storage batteries that are charged by power supply from an external power supply in series, and the other storage battery group connected in parallel to the one storage battery group Charging device,
A switch for switching between a state in which the external power source and each storage battery group are electrically connected to each other, and a state in which they are shut off;
A voltage sensor for detecting a voltage of each of the storage battery groups,
When it is determined that there is a voltage difference between the one storage battery group and the other storage battery group based on the detection value from each voltage sensor, the switch of the low voltage side storage battery group is closed. In addition, the switches of the storage battery group on the high voltage side are controlled to be in the open state, and when it is determined that the one storage battery group and the other storage battery group have substantially the same voltage, the switches are controlled to be in the closed state. A charging device for a power storage device for a working machine. In the charging device of the electrical storage device for work machines according to claim 1,
The controller calculates an absolute value of a difference between detection values from the voltage sensors, compares the calculation result with a previously stored threshold value, and if the calculation result is smaller than the threshold value, It is determined that the other storage battery group has substantially the same voltage, and otherwise, it is determined that a voltage difference is generated between the one storage battery group and the other storage battery group. A power storage device charging device for a working machine. A power storage device for a working machine comprising one storage battery group configured by connecting a plurality of storage batteries that are charged by power supply from an external power supply in series, and the other storage battery group connected in parallel to the one storage battery group Charging method,
A procedure for detecting the voltage of each storage battery group with a voltage sensor, and
Based on the detection value of the voltage sensor, there is a voltage difference between the one storage battery group and the other storage battery group, or the one storage battery group and the other storage battery group have substantially the same voltage. A procedure to determine if it exists,
When it is determined that a voltage difference is generated between the one storage battery group and the other storage battery group in the determining procedure, the high-voltage side storage battery group and the external power source are electrically disconnected, A procedure for electrically connecting a storage battery group on the low voltage side with the external power source and charging the battery group;
When it is determined in the determining procedure that the one storage battery group and the other storage battery group have substantially the same voltage, a procedure for electrically connecting each storage battery group with the external power source and charging A method for charging a power storage device for a work machine, comprising: The method for charging the power storage device for a work machine according to claim 3,
The determining step includes a step of calculating an absolute value of a difference between detection values from the voltage sensors, and a step of comparing the calculation result with a prestored threshold value, and the calculation result is smaller than the threshold value. In this case, it is determined that the voltage between the one storage battery group and the other storage battery group is substantially the same, and in other cases, there is a voltage difference between the one storage battery group and the other storage battery group. A method of charging a power storage device for a work machine, characterized in that the procedure is to determine that it occurs.

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