JP2011064063A5 - - Google Patents

Description

Hybrid excavator

The present invention relates to a hybrid excavator , and more particularly, to a hybrid excavator including an electric motor that charges a storage battery using power from an engine and assists driving of the engine using electric power of the storage battery .

  As shown in FIGS. 13 and 14A, the conventional hydraulic excavator (working machine) drives the hydraulic pump 8 using the power of the engine (internal combustion engine) 7 mounted on the upper swing body 1, The hydraulic oil discharged from the hydraulic pump 8 is supplied to the boom cylinder 3C for driving the boom 3, the arm cylinder 4C for driving the arm 4, the bucket cylinder 5C for driving the bucket 5, and further for turning through the hydraulic controller. These parts are driven by supplying them to the respective actuators provided in the hydraulic motor 6 and the traveling hydraulic motor 9 of the traveling part 2 (see Patent Document 1).

  In recent years, in response to changes in society where fuel saving performance, low pollution performance, low noise performance, etc. that consider the global environment are important, substituting the hydraulic pump 8 in work machines, and also electric The one using a motor has appeared.

  For example, there is a work machine configured as shown in FIG. FIG. 14B shows an example of a configuration diagram in which a hydraulic excavator is hybridized (hydraulic-electric hybrid) using an electric motor.

  In this configuration diagram, the hydraulic pump 8 is driven using the power of the engine 7, and the pressure oil is supplied to the actuators provided in the boom 3, the arm 4, the bucket 5, and the traveling hydraulic motor 9 in the above-described example. And in common. However, it differs from the above example in that a generator motor 10 provided so as to interrupt between the engine 7 and the hydraulic pump 8 is provided. The generator motor 10 is supplied with electric power from a battery (storage battery) 13, assists in driving the engine 7 and the hydraulic pump 8, and charges the battery 13 using power from the engine 7. Is possible.

  Each unit such as the bucket 5 is supplied with pressure oil from a hydraulic pump 8 and is provided with a generator motor 11. The generator motor 11 is a generator for generating power using the power of each unit and regenerating the power to the battery 13 for reuse. That is, the movement of each unit in the direction in which the potential energy rises uses the driving force of the hydraulic oil from the hydraulic pump 8 to move, and the movement in the direction in which the position energy of each unit decreases decreases the released energy. Then, the generator motor 11 is driven to generate electric power, and the electric power is regenerated.

  By adopting the configuration as described above, low fuel consumption performance, low pollution performance, low noise performance, and the like are improved.

JP 2002-242234 A

  As described above, when the driving method using the electric motor is adopted even in part, a battery as a power supply device is required. In consideration of power regeneration, a storage battery (secondary battery and capacitor) that can freely discharge and store electricity is indispensable as a battery.

Here, to be able to accurately calculate the charging energy to the power storage value, the battery managed ment, further adjustment of the power distribution of energy management of the entire hybrid excavator becomes difficult. If it becomes difficult to adjust the energy management of the entire hybrid excavator , deterioration of overcharge / overdischarge of the storage battery is promoted .

The present invention provides hybrid was made in order to prevent such problems from occurring, battery management, even that can efficiently adjust the power distribution of the energy management of the entire hybrid excavator The challenge is to provide a type excavator .

The present invention relates to a hybrid-type shovel equipped with an engine and a battery to the upper rotating body, performs charging by utilizing the power from the engine to the storage battery, the engine by utilizing the power of the storage battery an electric motor for assisting the driving of a inverter which is connected to the electric motor, a buck-boost converter is arranged between the battery and the inverter, it is disposed between the battery and the 該昇buck converter, voltage measurement means for measuring a voltage of the storage battery, by using the voltage value, and the stored energy calculation means to calculate the energy stored in the battery, the control of charging and discharging a power storage energy of at least storage battery The above-described problem is solved by configuring a hybrid excavator including a battery state management unit that performs the above.

Thus, the battery can be charged and discharged control of the hybrid excavator equipped with an engine and the power storage pond on which to grasp the state of charge (battery) more accurately.

By applying the present invention, battery management, even it is possible to efficiently adjust the power distribution of the energy management of a hybrid type excavator as a whole.

Block diagram of battery management which is the main part of the present invention System configuration diagram of capacitor unit, buck-boost converter unit and inverter Diagram showing an example of capacitor configuration Capacitor unit equivalent circuit diagram Flow chart of SOC monitor A table showing the names of symbols in FIG. Graph showing the progress of SOC measurement Relationship diagram between internal resistance and SOH Equivalent circuit diagram when measuring the internal resistance of the capacitor unit in the buck-boost converter operation state Equivalent circuit diagram when measuring the internal resistance of the capacitor unit when the buck-boost converter is stopped Flow chart of SOH monitor A table showing the names of symbols in FIG. Hydraulic excavator (work machine) described in Patent Document 1 (A) is a diagram showing the construction of a hydraulic excavator, (B) is a diagram showing the construction of a hybrid-type shovel of hydraulic and electric motor

  Hereinafter, an example of an embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

In the following description, the entire work machine (hybrid excavator) will not be described. However, as described in the background art as an example, the work machine is equipped with an “electric motor that operates using the power of the storage battery”. It will be explained on the premise that there is.

  FIG. 1 is a block diagram of battery management provided in a work machine according to the present invention. The battery management here is a function for managing the state of the storage battery used in the work machine.

  The battery management shown in FIG. 1 includes a battery state management unit 100, a charge / discharge control unit 200, a capacitor unit 300 as a storage battery, an SOH monitor 400 corresponding to an internal resistance value calculation unit and a deterioration state determination unit, an SOC It is configured to include at least a monitor 500 and an alarm 600 corresponding to notification means.

  The battery state management unit 100 is a part capable of transmitting a command signal related to charge / discharge control to a charge / discharge control unit 200 described later.

  The charge / discharge control unit 200 receives a signal from the battery state management unit 100 and controls charge / discharge of the capacitor unit 300 through a converter described later, and can measure the current value I and voltage value V of the capacitor unit 300. It is an important part.

  The capacitor unit 300 functions as a storage battery provided in the work machine according to the present embodiment. In this embodiment, a capacitor is employed as a storage battery, but the present invention is not limited to this, and for example, a secondary battery such as a lithium ion battery, a nickel cadmium battery, a nickel metal hydride battery, a lead battery, or a manganese battery is used. Also good.

  The SOH monitor 400 receives the converter operating state flag, the capacitor current value I, and the capacitor voltage value V from the charge / discharge control unit 200 as information, and passes through a predetermined procedure (details will be described later). While calculating a value, the deterioration degree of the capacitor unit 300 can be determined. That is, the SOH monitor 400 corresponds to an internal resistance value calculation unit and a deterioration state determination unit.

  The SOC monitor 500 receives the information on the capacitor current value I and the capacitor voltage value V from the charge / discharge control unit 200 and the information on the internal resistance value of the capacitor from the SOH monitor 400 described above, and determines the charge amount of the capacitor unit 300 in real time. Can be calculated.

  Degradation level of the capacitor output from the SOH monitor 400 (output as a parameter called SOH, details will be described later), the internal resistance of the capacitor, and the charge amount of the capacitor output from the SOC monitor 500 (output as a parameter called SOC) The information of which will be described later is fed back to the battery state management unit 100.

  A signal is output to an alarm 600 serving as a notification unit according to the degree of deterioration of the capacitor unit 300 determined by the SOH monitor 400. In the present embodiment, the “predetermined process” performed by the alarm as the notification means is an alarm sound. Note that the notification means is not limited to this, and visual notification such as a light emitting body such as an LED or a display on an operation panel may be used, or notification may be made sensibly through vibration. Furthermore, you may employ | adopt combining these.

  Next, it demonstrates using FIG. FIG. 2 is a system configuration diagram of the capacitor unit 300, the buck-boost converter unit 201, and the inverter 700.

  The capacitor unit 300 includes a capacitor body 301 in which capacitor cells are gathered and a fuse 303 that functions as a safety device for the capacitor body 301. The capacitor unit 300 is connected to the step-up / down converter unit 201 via a reactor 305 for effectively using inductive reactance. The step-up / down converter unit 201 is controlled by the charge / discharge control unit 200 described with reference to FIG. The step-up / down converter unit 201 includes a step-up / down converter 202. The step-up / down converter 202 adjusts the charging voltage to the capacitor unit 300 and controls the discharging voltage from the capacitor unit 300. The step-up / down converter unit 201 is connected to an inverter 700, and is electrically connected to an electric motor (not shown) of the work machine via the inverter 700. In the present embodiment, only one inverter 700 is connected, but a plurality of inverters 700 may be connected.

  In the present embodiment, a capacitor unit 300 is employed as a storage battery. The capacitor main body 301 in the capacitor unit 300 is configured as shown in FIG. 3, for example. Here, 20 capacitor cells are connected in series to form one module, and 7 modules are further connected in series to form one bank. Further, the capacitor main body 301 is configured by connecting the banks in four parallel. For example, when the rated voltage per capacitor cell is designed to be 2.7 V, the rated voltage per module is 54 V, and the rated voltage per bank is 378 V. Of course, the configuration of the capacitor is not limited to the configuration example described above. Further, the storage battery in the present invention is not limited to the capacitor.

[SOC monitor]
Next, the SOC monitor 500 shown in FIG. 1 will be described.

  The SOC monitor 500 can calculate the charge amount of the capacitor unit 300 that is a storage battery. By using the information on the charge amount of the capacitor unit 300 calculated here, it is possible to determine the switching of charge / discharge in the battery state management unit 100 and to adjust the power distribution of the energy management of the entire work machine. That is, it is desirable to always calculate the charge amount of the capacitor unit 300 during operation of the work machine.

  The amount of charge of the capacitor unit is determined using a parameter called SOC (State Of Charge).

  This SOC is the ratio (E ′ / E) of the stored energy E ′ at the current time (at the time of SOC measurement) to the stored energy E at the rated voltage of the capacitor unit 300 (for example, 378 V in the configuration example of the capacitor described above). It is represented by

  This will be described more specifically with reference to FIG. FIG. 4 is an equivalent circuit diagram of the capacitor unit.

The capacitance value of the capacitor body 301 C, when the rated voltage value of the capacitor body 301 and Vcp0, stored energy E at rated voltage of the capacitor unit 30 0 is expressed by the following equation.

Similarly, when the voltage of the capacitor body 301 does not reach the rated voltage value, for example, the stored energy E ′ when the voltage value (open voltage value) of the capacitor body 301 is VCP1 (current time) is expressed by the following equation. .

However, at this time, it is impossible to actually measure only the open circuit voltage value (VCP) of the capacitor body 301. That is, the capacitor unit 300 has an internal resistance (resistance value RS), which causes a voltage drop. Therefore, even if measured, the voltage after the voltage drop due to the internal resistance (resistance value RS) is measured. Since the voltage drop due to the internal resistance (resistance value RS) is obtained by integrating the current flowing through the internal resistance (resistance value RS) and the internal resistance value, the actual capacitor unit 300 in which this voltage drop has occurred. When the voltage value is VC, VC P1 is expressed by the following equation.

In addition, the SOC value indicating the charge amount of the capacitor unit 300 is equal to the stored energy E ′ of the capacitor unit 300 at the present time (at the time of SOC measurement) with respect to the stored energy E at the rated voltage of the capacitor unit 300 as described above. Because it is a ratio
SOC = E '/ E (4)
It becomes.

Therefore, when derived from the above-described equations (1) to (4), this SOC is expressed by the following equation.

  Next, a specific flow of measurement of the SOC (the order in which the SOC monitor 500 measures the charge amount of the capacitor unit 300) will be described using the flowchart of FIG.

  First, the SOC monitor 500 is activated (S501).

  Next, the current value I of the capacitor unit 300 is read (S502).

  Next, it is determined whether or not the current value I of the capacitor unit 300 has been read (S503). If the current value I has been read, the process proceeds to the next step S504. If the current value I has not been read, the process returns to step S502.

  Next, the voltage value VC of the capacitor unit 300 is read (S504).

  Next, it is determined whether or not the voltage value VC of the capacitor unit 300 has been read. If the voltage value VC is read at this time, the process proceeds to the next step S506, and if the voltage value VC is not read, the process returns to step S504.

  Next, the internal resistance value RS of the capacitor unit 300 is read (S506).

  Next, it is determined whether or not the internal resistance value RS of the capacitor unit 300 has been read (S507). At this time, if the internal resistance value RS is read, the process proceeds to the next step S508, and if the internal resistance value RS is not read, the process returns to step S506.

  Next, the SOC is calculated based on these three read data (S508).

  Next, the calculated SOC value is output (S509), and the process ends.

  Although not shown in the flowchart, the flow of the SOC measurement described here is repeatedly measured at each interval based on a preset SOC measurement interval parameter.

  FIG. 6 is a table showing the name of the symbol and the reference destination of each value in the flow of the flowchart of FIG.

  Symbol VCP0 is a rated voltage value of the capacitor body 301, and this value is read with reference to a preset parameter. VC is a voltage value (at the time of SOH measurement) of the capacitor unit 300, and is read with reference to an output value from the charge / discharge control unit 200. I is a current value (at the time of SOH measurement) of the capacitor unit, and this value is also read with reference to an output value from the charge / discharge control unit 200. RS is an internal resistance value of the capacitor unit 300, and this value is read by referring to a value output from the SOH monitor 400 (details will be described later). It should be noted that the internal resistance value RS output from the SOH monitor 400 at the time of starting the work machine is continuously used until the work machine is started and then stopped. tSOC indicates an SOC measurement interval, and the SOC measurement (flowchart shown in FIG. 5) is executed at each set interval with reference to a preset parameter.

  When the SOC is measured under the flow as described above, a graph as shown in FIG. 7 is obtained. FIG. 7 is a graph showing the progress of SOC measurement.

  Since the voltage value VC and the current value I of the capacitor unit 300 are constantly changing during operation, the value of the SOC is constantly measured during the operation of the work machine (at intervals based on tSOC).

[SOH monitor]
Next, the SOH monitor 400 will be described with reference to FIGS.

The capacitor unit 300, which is a storage battery, causes an increase in internal resistance or a decrease in capacitance due to long-term use, overdischarge / overcharge, heat generation, and the like. The characteristics will change. Therefore, in order for the capacitor unit 300 to perform appropriate charge / discharge during operation of the work machine, it is necessary to measure and grasp the deterioration state of the capacitor unit 300 in advance. By Knowing this, battery Lima ent, even it is possible to perform efficiently the energy management of the entire working machine. Further, when a predetermined deterioration level is reached, the fact is notified to prompt the replacement of the storage battery, and the adverse effects caused by the deterioration, that is, the operation of the work machine cannot be performed or the operation is slowed down. It is possible to prevent the occurrence of adverse effects such as the inability to exert a specified force (for example, propulsion, lifting, excavation, etc.).

  The degree of deterioration of the capacitor unit is determined using a parameter called SOH (State Of Health).

In the SOH monitor 400, the degree of deterioration of the capacitor unit 300 is determined using the increase amount of the internal resistance value RS of the capacitor unit 300 as an index. More specifically, the internal resistance value before use of the capacitor unit 300 (for example, a value at the time of a new product, a value measured in advance before the capacitor unit 300 is actually used after being mounted on a work machine, and further described later. This is expressed as a ratio between the initial value RS0 of the capacitor unit 300 determined by the internal resistance value determination means and the internal resistance value RS at the present time (at the time of SOH measurement), and the internal resistance value RS at the time of measurement is used. The lifetime of the capacitor unit 300 is set when n times the previous internal resistance value RS0 (deterioration coefficient). Deterioration degree coefficient of the time (n) is an optionally settable parameter (second parameter), and type of work machine, set according to the type of battery to be used. For example, if the working machine is used frequently and the charging / discharging performance of the storage battery greatly affects the fuel consumption rate or the operating performance, the deterioration factor coefficient can be calculated because the merit of replacing the storage battery early is great. It is possible to reduce the replacement cost of the storage battery by setting it lower and setting it higher otherwise. Moreover, a set value can also be determined by the property of the site | part operated with a storage battery. In other words, if it is a part where the operation is frequently repeated, the deterioration factor coefficient is set low because it greatly affects the fuel consumption rate and the operating performance as described above, and prompt replacement is promoted. It is possible to reduce the replacement cost of the storage battery by setting it higher. Of course, it can be set according to the user's intention.

The calculation formula of SOH is expressed by the following formula.

  Based on this equation, the value of SOH changes as shown in FIG. The description will be made assuming that “2” is set to the deterioration degree coefficient (n).

  Since the internal resistance value immediately after the start of use of the capacitor unit 300 is substantially the same as RS0 which is the capacitor internal resistance value before use (for example, when it is new), RS0 is subtracted from the doubled RS0. The molecule is RS0. As a result, SOH becomes 1. Thereafter, as the capacitor unit 300 is used, the internal resistance value RS of the capacitor unit 300 gradually increases and reaches a value based on a preset deterioration factor (n times the internal resistance value before use). Becomes 0. That is, it becomes the life of the preset storage battery.

  Next, a method for calculating the internal resistance value of the capacitor unit 300 will be specifically described with reference to FIGS. 9 and 10. FIG. 9 is an equivalent circuit diagram when measuring the internal resistance of the capacitor unit in the operation state of the buck-boost converter. FIG. 10 is an equivalent circuit diagram when measuring the internal resistance of the capacitor unit when the buck-boost converter is stopped.

From the equivalent circuit shown in FIG. 9, the internal resistance RS of the capacitor unit 300 in the operation state of the buck-boost converter is expressed by the following formula (see formula (3)).

Therefore, in order to calculate the internal resistance RS, it is necessary to measure the open circuit voltage VCP1 of the capacitor body 301. As described in the SOC, it is impossible to measure only the open circuit voltage value VCP1. That is, the capacitor unit 300 has an internal resistance (resistance value RS), which causes a voltage drop. Therefore, even if measured, the voltage after the voltage drop due to the internal resistance (resistance value RS) is measured. Since the voltage drop due to the internal resistance (resistance value RS) is obtained by integrating the current flowing through the internal resistance (resistance value RS) and the internal resistance value, the following equation is established.

Here, if the voltage drop due to the internal resistance RS does not occur, the open circuit voltage VCP1 and the voltage value of the capacitor unit 300 match. That is, as shown in FIG. 10, assuming that the voltage value of the capacitor unit 300 when the current I flowing through the capacitor unit 300 is 0 is VC0, VC0 is the open circuit voltage of the capacitor body 301 because the current I = 0. In agreement with the value VCP1, the following equation holds.

Accordingly, the voltage value VC of the capacitor unit 300 when current flows through the capacitor unit 300 (I ≠ 0) and the voltage value VC0 of the capacitor unit 300 when current does not flow through the capacitor unit 300 (I = 0). If the above is measured, substituting it into the above equation (7), the following equation is established.

  Here, control of the current to the capacitor unit 300 (I = 0 or I ≠ 0) can be realized by ON / OFF of the buck-boost converter 202.

  As a result, SOH can be calculated using the above equation (6).

Equation (6) is shown again.

  Thus, the internal resistance calculation means in this embodiment calculates the internal resistance value from the voltage of the storage battery when no current flows through the capacitor unit (storage battery) 300 and the voltage of the storage battery when the current flows. It is a means for calculating.

Substituting the previously determined internal resistance value RS into this equation (6), the following equation is established.

  Using this equation (11), the deterioration degree (SOH) of the capacitor unit 300 can be calculated.

  Next, a specific flow of SOH measurement described so far (the order in which the SOH monitor 400 measures the deterioration degree of the capacitor unit 300) will be described.

  FIG. 11 is a flowchart of the SOH monitor 400.

First, the SO H monitor 400 is activated (S1201).

  Next, the operation command of the buck-boost converter 202 is set to “stop” (S1202).

Next, the operation state flag of the step-up / down converter 202 is observed (S1203).

  Next, it is determined whether or not the converter operation state flag is “stop” (S1204). If the converter operation state flag is “stop”, the process proceeds to the next step S1205. If the converter operation state flag is not “stop”, the process returns to step S1202.

  Next, the current value I of the capacitor unit 300 is measured (S1205).

  Next, it is determined whether or not the current value I of the capacitor unit 300 is “0” (S1206). At this time, if the current value I is “0”, the process proceeds to the next step S1207, and if the current value I is not “0”, the process returns to step S1205.

  Next, the voltage value VC0 of the capacitor unit 300 (the voltage value of the capacitor unit when the current value is 0) is read (S1207).

  Next, it is determined whether or not the voltage value VC0 of the capacitor unit 300 has been read (S1208). At this time, if the voltage value VC0 of the capacitor unit 300 is read, the process proceeds to the next step S1209, and if not, the process returns to step S1207. Next, the buck-boost converter 202 is activated to start charging the capacitor unit 300 (S1209). That is, a current flows through the capacitor unit 300.

  Next, the voltage value VC and current value I of the capacitor unit 300 in a state where current is flowing are read (S1210).

Next, it is determined whether the voltage value VC and current value I of the capacitor unit 300 have been read (S1211). If this time the voltage value VC and the current value I is read, the process proceeds to step S1212, when the voltage value VC and the current value I is not read, the process returns to step S1210.

  Next, the internal resistance value RS of the capacitor unit 300 is calculated using the above-described calculation formula (S1212).

  Steps S1201 to S1212 described so far correspond to the internal resistance value calculating means in the present invention.

  Next, two preset parameters (capacitor internal resistance value RS0 (first parameter) before use, deterioration factor n (second parameter)) before use are read (S1213).

  Next, it is determined whether or not both parameters have been read (S1214). If both parameters are read at this time, the process proceeds to step S1215. If both parameters are not read, the process returns to step S1213.

  Next, SOH is calculated based on the read information (S1215).

  Next, it is determined whether or not the calculated value is “0 (third parameter)” or less (S1216). If the calculated value is “0” or less, the process proceeds to step S1217. If the calculated value is not “0” or less, the process ends.

  Steps S1213 to S1216 described so far correspond to the deterioration state determination means in the present invention. Thus, the deterioration state determination means in this embodiment includes the first parameter (RS0) set for each storage battery, the second parameter (n) set according to the type of work machine, and the internal Depending on the internal resistance value (RS) calculated by the resistance value calculation means, that is, using three data of the first parameter (RS0), the second parameter (n), and the internal resistance value (RS). It is a determination unit that compares the derived numerical value with a preset third parameter to determine the deterioration state.

  Next, an alarm is output (S1217), and the process ends.

  The function of the SOH monitor described here is executed before the work machine is started and the capacitor unit (storage battery) 300 can be charged. More specifically, it is executed after the key is inserted into the work machine and before the engine is started and the work machine is in a workable or movable state.

  FIG. 12 is a table showing the name of the symbol and the reference destination of each value in the flow of the flowchart of FIG.

  Symbol VC0 is a voltage value of capacitor unit 300 when the converter is stopped, and this value is read with reference to an output value from charge / discharge control unit 200. VC is a voltage value of the capacitor unit 300 during the converter operation, and this value is also read with reference to an output value from the charge / discharge control unit 200. RS0 is an internal resistance value of the capacitor unit 300 before use, and this value is read with reference to a preset parameter (first parameter). I is the current value of the capacitor unit 300, and this value is also read with reference to the output value from the charge / discharge control unit 200. n is a deterioration degree coefficient, and this value is read with reference to a preset parameter (second parameter).

  As described above, the electric motor that operates using the power of the storage battery, the internal resistance value calculating means for calculating the internal resistance value of the storage battery, and the internal resistance value calculated by the internal resistance value calculating means are used. When the work machine is started, a deterioration state determination unit for determining the deterioration state of the storage battery and a notification unit that performs predetermined processing based on the determination result of the determination unit are configured. It is possible to know the deterioration state of the storage battery.

  Note that the mathematical expressions used in the description of the embodiments are merely examples, and do not exclude calculation using mathematical expressions other than the mathematical expressions.

The present invention can be widely applied to hybrid excavators .

DESCRIPTION OF SYMBOLS 100 ... Battery state management part 200 ... Charge / discharge control part 201 ... Buck-boost converter unit 202 ... Buck-boost converter 300 ... Capacitor unit 301 ... Capacitor main body 400 ... SOH monitor 500 ... SOC monitor 600 ... Alarm 700 ... Inverter

Claims (4)

A hybrid excavator with an engine and a storage battery mounted on an upper rotating body ,
Performs charging by utilizing the power from the engine to the storage battery, an electric motor for assisting the driving of the engine by utilizing the power of the storage battery,
An inverter connected to the electric motor;
A step-up / down converter disposed between the storage battery and the inverter;
A voltage measuring means disposed between the step-up / step-down converter and the storage battery for measuring the voltage of the storage battery ;
Using the voltage value, and the stored energy calculation means to calculate the energy stored in said storage battery,
A battery state management unit that performs charge / discharge control using at least the energy stored in the storage battery ;
Hybrid excavator with In claim 1,
A reactor is disposed between the storage battery and the buck-boost converter,
A switch arranged in series with the reactor;
A hybrid excavator comprising a resistor arranged in parallel with the switch . In claim 1 or 2,
A charge amount calculating means for calculating a charge amount based on the stored energy;
A battery state management unit that generates a charge / discharge command value based on the calculated charge amount;
Hybrid excavator with In any one of claims 1 to 3,
A hybrid excavator, wherein a fuse is provided in series with the storage battery .