JP2007046584A - Energy storage device for construction machinery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy storage device for construction machinery capable of storing and radiating required energy instantaneously and reducing cost of the whole construction machinery. <P>SOLUTION: This energy storage device 30 is provided with a flywheel electric power generator 32, a flywheel 31 connected with the flywheel electric power generator 32, and a flywheel controller 33 for controlling the flywheel electric power generator 32. The flywheel controller 33 rotates and drives the flywheel 31 by switching the flywheel electric power generator 32 into an electric motor to store energy in the flywheel 31 when it is determined that a control voltage value is above a target voltage value and generates electric power by rotation energy of the flywheel 31 by switching the flywheel electric power generator 32 into a power generator to supply current to a power supply line when it is determined that a control voltage value is below the target voltage value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an energy storage device that is applied to a construction machine including an upper-part turning body that is driven by an electric motor and that stores and releases energy.

  In recent years, in response to demands for higher energy efficiency, exhaust gas purification, and noise reduction, a hybrid type electric swing in which the upper swing body provided with a cab and the like is driven by a swing motor and the work machine and the traveling body are driven hydraulically. Excavators are being developed. The electric power necessary for the swing motor for driving the swing body is mainly used as generated by the generator driven by the engine, and the power is stored in a capacitor or the like or discharged as necessary. Therefore, effective use of energy is aimed at.

  Incidentally, a method has been proposed in which a part of the driving force of the engine is stored as the rotational force of the flywheel as mechanical energy, and this energy is used as necessary (see, for example, Patent Document 1).

JP 2001-99103 A

  However, in Patent Document 1, the flywheel is disposed on a shaft between the engine and the hydraulic pump via a clutch, and the flywheel and the engine shaft are integrated when the clutch is coupled. When driving, there is a problem that a very large acceleration torque is required, and a necessary hydraulic pump output cannot be obtained when necessary.

  Further, the energy accumulated as the rotational force of the flywheel is only used for driving the hydraulic pump as mechanical energy. In a hybrid type electric swing excavator in which the swing body is driven by an electric motor, the drive of the swing body is performed. Cannot contribute to anything. Therefore, the electric power necessary for the swing motor must be supplied by a generator connected to the engine as before, and a generator having the same capacity as that of the swing motor is required. Since the means is also required as before, it is expensive in terms of cost.

  An object of the present invention is to provide an energy storage device capable of storing and releasing necessary energy instantaneously and reducing the cost of the entire construction machine.

  An energy storage device for a construction machine according to claim 1 of the present invention is a flywheel connected to a common power line together with a swing motor that drives a swing body of the construction machine and a motor generator that supplies electric power to the swing motor. A motor generator, a flywheel connected to the flywheel motor generator for storing energy, and a flywheel control device for controlling the flywheel motor generator, wherein the flywheel control device includes the flywheel Voltage level determination means for determining whether the control voltage value to be controlled by the motor generator is equal to or higher than the target voltage value, and the control mode of the flywheel motor generator based on the determination result of the voltage level determination means Control mode switching means for switching, and the control voltage value is set to the target voltage by the voltage level determination means. When it is determined that the value is greater than or equal to the value, the control mode switching means accumulates energy in the flywheel by switching the control mode of the flywheel motor generator to an electric motor and rotationally driving the flywheel, When it is determined by the voltage level determination means that the control voltage value is lower than the target voltage value, the control mode switching means switches the control mode of the flywheel motor generator to the generator and uses the rotational energy of the flywheel. Power generation is performed, and current is supplied to the power supply line.

  A construction machine energy storage device according to claim 2 of the present invention is the construction machine energy storage device according to claim 1, wherein the flywheel control device includes a target voltage storage means for storing the target voltage value. The voltage level determination means detects the predetermined voltage value acquired from the target voltage storage means and the line voltage acquired from the line voltage detection means that detects the line voltage of the power supply line and outputs the line voltage as the control voltage value. It is characterized by comparing the value.

  The construction machine energy storage device according to claim 3 of the present invention is the construction machine energy storage device according to claim 1, wherein the flywheel control device converts the power generation voltage of the flywheel motor generator to the control voltage. Power generation voltage output means for outputting as a value, the voltage level determination means compares the power generation voltage value of the motor generator with the power generation voltage value of the flywheel motor generator acquired from the power generation voltage output means It is characterized by doing.

  The construction machine energy storage device according to claim 4 of the present invention is the construction machine energy storage device according to claim 2 or claim 3, wherein the flywheel control device is configured such that the motor generator capacity and the flywheel control device are the same. A control gain setting means in which a control gain determined by the capacity of the wheel motor generator is set; and a voltage control means for controlling the control voltage value, the voltage control means according to the control gain setting, A current determined according to a deviation between the control voltage value and the target voltage value is supplied to the flywheel motor generator to store energy in the flywheel, or the flywheel motor generator supplies the power source. It is characterized by being supplied to a line.

  The construction machine energy storage device according to claim 5 of the present invention is the construction machine energy storage device according to claim 4, wherein the control voltage value is greater than or equal to the target voltage value. The ratio of the current supplied to the motor generator and the current supplied from the power line to the flywheel motor generator, or the motor generator when the control voltage value is lower than the target voltage value The ratio of the current supplied to the power supply line and the current supplied to the power supply line by the flywheel motor generator depends on the ratio between the control gain of the motor generator and the control gain of the flywheel motor generator. It is characterized by being fixed.

  In the above, according to the first aspect of the present invention, the surplus electrical energy is converted into mechanical energy and stored in the flywheel, while the stored energy is converted into electrical energy and released. It can be stored and released instantly. In addition, this makes it possible to reduce or eliminate the capacity of the electrical power storage device, which is a power supply source, as compared with the conventional case, thereby reducing the cost of the entire construction machine. Furthermore, since the swing motor, the motor generator, and the flywheel motor generator are connected to a common power supply line, energy can be effectively used among them.

  According to the invention of claim 2, since the control voltage value of the flywheel motor / generator is the power line voltage value commonly connected with the swing motor and the motor / generator, excess or deficiency of energy supply between them The state can be monitored directly, and energy can be quickly distributed according to each driving situation.

  According to the invention of claim 3, since the control voltage value of the flywheel motor generator is the power generation voltage of itself, and the target value is the power generation voltage of the motor generator, the control by the flywheel control device can be independent, The flywheel control device can be handled as the same function as the secondary battery.

According to the invention of claim 4, since the control gain used for voltage control of the flywheel motor generator is determined by the capacity of the motor generator and the capacity of the flywheel motor generator,
It is possible to prevent the current supplied from the power line to the flywheel motor generator or the current supplied from the flywheel motor generator to the power line from exceeding the respective capacities.

  According to the invention of claim 5, since the respective voltage control gains are determined by the capacity of the motor generator and the capacity of the flywheel motor generator, current supply or consumption can be appropriately distributed between the two.

[First Embodiment]
[1-1] Overall Configuration A first embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing the entirety of an electric swing excavator (construction machine) 1 according to the present embodiment, and FIG. 2 is a diagram showing a connection relationship between each control device constituting the electric swing excavator 1 and a DC line. . FIG. 3 is a diagram showing an output state when the swing body 9 of the electric swing shovel 1 is controlled.

  In FIG. 1, an electric swing excavator 1 is a so-called hybrid construction machine having a pair of hydraulic pumps 3 and a motor generator 4 driven by an engine 2, respectively, from a hydraulic pump 3 supplied via a control valve 3A. The boom cylinder 5, the arm cylinder 6, the bucket cylinder 7, and the hydraulic motor 8 for the left and right lower traveling bodies are driven by the hydraulic pressure, and the upper swing body 9 is driven to swing by the electric power from the motor generator 4.

  In the electric swing excavator 1 of the present embodiment, the electric energy supply unit 10 is configured including the motor generator 4 that supplies electric energy to the upper swing body 9, and the upper swing body 9 driven by this electric energy. The electric energy turning part 20 is comprised. In addition, the electric swivel excavator 1 is an energy storage device 30 provided so as to be able to store and release electric energy, and a swing that comprehensively controls the electric energy supply unit 10, the electric energy swivel unit 20, and the energy storage device 30. And a control unit 40.

  The electric energy supply unit 10 includes the motor generator 4 described above and a motor generator control device 11 that controls the motor generator 4. The motor generator 4 is a motor generator that generates power using the engine 2 as a drive source and also functions as a motor. That is, when functioning as a generator, the driving force of the engine 2 is converted into electric energy, and when functioning as an electric motor, driving of the engine 2 with respect to the hydraulic pump 3 is assisted as necessary. The motor generator control device 11 switches the control mode for causing the motor generator 4 to function as a generator or a motor based on a command from a turning control unit 40 described later. Further, the motor generator control device 11 controls the torque and rotation speed of the motor generator 4 based on the control command from the turning control unit 40.

  The electric energy turning unit 20 includes the turning body 9 described above, a turning motor 21 that drives the turning body 9, and a turning motor control device 22 that controls the turning motor 21. Of these, the swing motor 21 is a DC brushless motor and functions as a generator to regenerate energy when the swing body 9 is braked. The swing motor control device 22 controls the torque, rotation speed, rotation position, and the like of the swing motor 21 based on a control command from the swing control unit 40.

  The energy storage device 30 includes a flywheel 31 that is an energy storage unit, a flywheel motor / generator 32 that drives the flywheel 31, and a flywheel control device 33 that controls the flywheel motor / generator 32. Yes. Of these, the flywheel motor generator 32 is an AC motor generator having functions as a motor and a generator. When the flywheel motor / generator 32 functions as an electric motor, the flywheel 31 is rotationally driven to convert electrical energy into mechanical energy and store it. Mechanical power is converted into electric energy and released by power generation using the rotational force of the wheel 31.

  The flywheel control device 33 switches the control mode for causing the flywheel motor / generator 32 to function as a generator or a motor, controls the voltage when the flywheel motor / generator 32 generates power or operates the motor, and rotates the flywheel 31. Perform number control. For this reason, the flywheel control device 33 is provided with means for determining a deviation between the control voltage value to be controlled by the flywheel motor generator 32 and the target voltage value. Further, the flywheel motor generator 32 is provided with a rotation speed sensor 34, and outputs the detected rotation speed signal to the flywheel control device 33.

  The turning control unit 40 issues a control command to the turning electric motor control device 22 based on the output value of the rotation speed sensor 41 provided in the turning electric motor 21 and the operation amount of the turning lever 43, thereby turning the turning body 9. To control. Further, the turning control unit 40 adjusts the amount of power generated by the motor generator 4, issues a command related to the control of the motor generator 4 to the motor generator control device 11, and issues a command for the rotational speed to the engine 2. . In other words, the turning control unit 40 issues a command to the motor generator control device 11, the turning motor control device 22, and the engine 2, thereby giving a control command for the entire operation necessary for the turning operation of the turning body 9.

  In FIG. 2, the units 10 and 20 described above and the control devices 11, 22 and 33 of the energy storage device 30 are respectively connected on a common DC line. Further, a voltage sensor (line voltage detection means, see FIG. 1) 42 is provided on the DC line, and the motor generator 4 and the flywheel electric motor according to the detected line voltage value (control voltage value). The generator 32 can be controlled. Therefore, when the turning body 9 is driven to turn by the turning motor 21, the motor generator 4 and the flywheel motor generator 32 can jointly supply power to the turning motor 21. Further, at the time of regenerative braking of the swing motor 21, the regenerated electric power can be received by both the motor generator 4 and the flywheel motor generator 32.

This will be specifically described with reference to FIG.
When the operator tilts the swing lever 43 and drives the swing body 9 to turn, the current is sent from the DC line to the swing motor 21 via the swing motor control device 22, so the DC line voltage decreases. In this case, the flywheel control device 33 detects that the DC line voltage value is lower than the target voltage value, and causes the flywheel motor generator 32 to function as a generator. For this reason, in the flywheel motor generator 32, a generated current is generated by the rotational energy of the flywheel 31. Similarly, since the motor generator control device 11 causes the motor generator 4 to function as a generator, the motor generator 4 generates a generated current by the driving force of the engine 2. As a result, since the generated currents from the flywheel motor generator 32 and the motor generator 4 flow on the DC line, the DC line voltage value increases toward the target voltage value.

  Thereafter, when the operator performs an operation of returning the swing lever 43 to the neutral position to brake the swing body 9, the current generated by the regenerative action of the swing motor 21 flows into the DC line via the swing motor control device 22. The line voltage increases. In this case, the flywheel control device 33 detects that the DC line voltage value exceeds the target voltage value, causes the flywheel motor generator 32 to function as an electric motor, and a part of the electrical energy that exceeds the DC voltage value. Is converted into rotational energy by the rotation of the flywheel 31 and stored. Similarly, the motor generator control device 11 causes the motor generator 4 to function as an electric motor and assists the drive of the engine 2 with respect to the hydraulic pump 3, so that this amount of current is consumed. As a result, since the accumulated amount of mechanical energy converted by the flywheel motor / generator 32 and the current consumed by the motor / generator 4 are discharged from the DC line, the DC line voltage value becomes the target voltage value. Going down.

[1-2] Description of Flywheel Control Device 33 Next, the flywheel control device 33 that is characteristic of the present embodiment will be described in detail.
4, the flywheel control device 33 includes a flywheel reference speed storage unit 331, a correction voltage output unit 332, a target voltage storage unit 333, a voltage level determination unit 334, a control mode switching unit 335, a control gain setting unit 336, a voltage The control unit 337 and the control command execution unit 338 are configured.

The flywheel reference speed storage unit 331 stores a predetermined flywheel reference speed.
The correction voltage output means 332 generates power from the motor generator 4 based on the output value of the rotation speed sensor 34 provided in the flywheel motor generator 32 and the flywheel reference speed stored in the flywheel reference speed storage means 331. A power generation voltage correction value for correcting the voltage is calculated and output to the turning control unit 40. Here, speed control by PI (Proportional Integral) control using a deviation between the flywheel reference speed stored in the flywheel reference speed storage means 331 and the output value of the rotation speed sensor 34 is performed. .

  Here, the reason why the correction voltage output means 332 is provided is to prevent the rotation of the flywheel 31 from being greatly reduced only by voltage control, and in this case, it is impossible to generate power. Therefore, the flywheel 31 must always have an appropriate rotational speed so that energy can be repeatedly stored (charged) and released (discharged) at all times. Needs to be controlled so that the flywheel 31 continues to rotate at a specific rotational speed. Therefore, the correction voltage output means 332 performs speed control using the rotational speed of the flywheel motor generator 32, and outputs it to the turning control unit 40 as the power generation voltage correction value of the motor generator 4.

  The power generation voltage correction value is used for controlling the power generation amount of the motor generator 4 by the turning control unit 40, and increases the line voltage by increasing the power generation amount of the motor generator 4. As a result, the flywheel motor generator 32 functions as an electric motor and rotates the flywheel 31 to accumulate energy. For example, when the engine 2 is started, the flywheel 31 is not rotating at all, and thus the power generation voltage correction value is increased, thereby greatly increasing the power generation amount of the motor generator 4, and thus the flywheel motor generator 32. Rotates the flywheel 31 and accumulates energy.

  The target voltage storage means 333 stores a predetermined voltage value corresponding to a line voltage necessary for stably driving the swing motor 21. This voltage value becomes the generated voltage command value (target voltage value) for the flywheel motor generator 32. The generated voltage command value may be changed according to the load condition of the swing motor 21.

  The voltage level determination means 334 determines the sign of the deviation from the DC line voltage value using the predetermined voltage value stored in the target voltage storage means 333 as the generated voltage command value. That is, it is determined whether or not a value obtained by subtracting the DC line voltage value from the generated voltage command value is zero or more.

  The control mode switching unit 335 switches the control mode of the flywheel motor generator 32 based on the determination result of the voltage level determination unit 334. That is, when the deviation is positive, the control mode switching means 335 switches the function of the flywheel motor generator 32 to the generator mode, and when negative, the function of the flywheel motor generator 32 is changed to the motor mode. Switch to.

In the control gain setting means 336, the control gain of the voltage control means 337 is set. Here, a circuit setting is made so as to take a predetermined value.
The voltage control means 337 performs a voltage control calculation for bringing the DC line voltage close to a predetermined generated voltage command value, generates a command to the control command execution means 338 using the deviation, and controls this. Output to the command execution means 338. Here, P (Proportional) control using the control gain set by the deviation and control gain setting means 336 is performed as calculation means by the voltage control means 337, and an arithmetic circuit for that purpose is assembled. .

  FIG. 5 and FIG. 6 are diagrams showing voltage control gains of the flywheel motor generator 32 and the motor generator 4, and specifically show the relationship between voltage and current for each. That is, the control gain setting means 336 and the voltage control means 337 are obtained according to the dotted line in the figure with respect to the varying DC line voltage when the turning motor 21 functions as an electric motor or a generator by turning or braking the turning body 9. The circuit settings are such that current flows from the flywheel motor generator 32 and the motor generator 4 to the DC line, and from the DC line to the flywheel motor generator 32 and the motor generator 4.

For example, when the DC line voltage is lowered to the value A in FIG. 5 due to the turning drive of the turning body 9 by the turning electric motor 21, the current A1 from the flywheel motor generator 32 and the current A2 from the motor generator 4. Is supplied on the DC line.
Further, when the DC line voltage rises to the value B in FIG. 6 due to the regenerative action of the swing motor 21 accompanying the braking of the swing body 9, the current B 1 is supplied to the flywheel motor generator 32, and the motor generator 4 is supplied to the motor generator 4. A current B2 flows and is used for assisting the engine 2 with respect to the rotational drive of the flywheel 31 and the drive of the hydraulic pump 3, respectively (specifically, the fuel injection amount in the engine 2 is reduced).

  The supply distribution of current from the flywheel motor generator 32 and the motor generator 4 to the DC line when the DC line voltage is reduced and the current consumption distribution when the DC line voltage is increased are the flywheel motor generator 32 and It is determined by the capacity ratio of the motor generator 4. That is, if the capacity of the flywheel motor generator 32 is larger than the capacity of the motor generator 4, the voltage control gain of the flywheel motor generator 32 is set smaller.

  The control command execution unit 338 controls the drive of the flywheel motor generator 32 based on a command from the voltage control unit 337. Here, a drive circuit including a power element is used as the control command execution means 338.

[1-3] Control Flow by Flywheel Control Device 33 Next, a control flow by the flywheel control device 33 will be described based on FIG.
First, the flywheel control device 33 reads the DC line voltage value and the output value of the rotation speed sensor 34 provided in the flywheel motor generator 32 (Step 11: Steps in the drawings and in the following description). Simply abbreviated as “S”).

The correction voltage output means 332 calculates a power generation voltage correction value based on the rotational speed of the flywheel motor generator 32 and the flywheel reference speed stored in the flywheel reference speed storage means 331 (S12). The generated voltage correction value is output to the turning control unit 40.
The voltage level determination means 334 determines whether the sign of the deviation of the DC line voltage value from the generated voltage command value, that is, the value obtained by subtracting the DC line voltage value from the generated voltage command value is equal to or greater than zero ( S13).
When the sign here is positive, the control mode switching means 335 switches the function of the flywheel motor generator 32 to the motor mode (S14). On the other hand, when the sign is negative, the control mode switching means 335 switches the function of the flywheel motor generator 32 to the generator mode (S15).

Then, the voltage control unit 337 generates a command to the control command execution unit 338 using the deviation (S16).
The control command execution means 338 controls the drive of the flywheel motor generator 32 based on the command from the voltage control means 337 (S17).

[Second Embodiment]
FIG. 8 shows a second embodiment of the present invention.
In the present embodiment, the power generation voltage of the motor generator 4 is set as a power generation voltage command value (target voltage value) for the flywheel motor generator 32, and the comparison target of the power generation voltage command value is that of the flywheel motor generator 32. It differs from the first embodiment in that the generated voltage (control voltage value) is used. As a result, the control by the flywheel control device 33 can be independent and the flywheel control device 33 can be handled as the same function as the secondary battery.
In this embodiment, since the power generation voltage of the motor generator 4 is the power generation voltage command value for the flywheel motor generator 32, target voltage storage means for storing a predetermined voltage value is not necessary and is provided. Absent.

  On the other hand, since the power generation voltage command value is compared with the power generation voltage of the flywheel motor generator 32, the power generation voltage output means 339 for outputting the power generation voltage of the flywheel motor generator 32 is required. It is provided in the control device 33. At the same time, the power generation voltage correction value calculated by the correction voltage output means 332 is fed back inside the flywheel control device 33 and used for determination by the voltage level determination means 334. As a result, the speed control of the flywheel motor / generator 32 affects the voltage control in the flywheel control device 33 and acts in the direction in which the flywheel motor / generator 32 functions as a generator.

  Accordingly, the voltage level determination means 334 uses the power generation voltage of the motor generator 4 as the power generation voltage command value, and the power generation voltage correction value output from the correction voltage output means 332 and the power generation voltage of the flywheel motor generator 32. The sign of the deviation of the sum with respect to the generated voltage command value is determined. That is, it is determined whether or not the value obtained by subtracting the generated voltage correction value and the generated voltage value of the flywheel motor generator 32 from the generated voltage command value is zero or more. Other control structures are the same as those in the first embodiment, and a description thereof is omitted here.

Next, a control flow by the flywheel control device 33 will be described based on FIG.
First, the flywheel control device 33 reads the generated voltage value of the motor generator 4, the generated voltage value of the flywheel motor generator 32, and the output value of the rotation speed sensor 34 provided in the flywheel motor generator 32. Perform (S21).

The correction voltage output means 332 calculates a power generation voltage correction value based on the rotational speed of the flywheel motor / generator 32 and the flywheel reference speed stored in the flywheel reference speed storage means 331, as in the first embodiment. (S22).
The voltage level determination means 334 is a sign of the deviation of the sum of the power generation voltage correction value and the power generation voltage value of the flywheel motor generator 32 with respect to the power generation voltage command value, that is, the correction voltage value and the flywheel electric motor from the power generation voltage command value. It is determined whether the sign of the value obtained by subtracting the generated voltage value of the generator 32 is positive or negative (S23).

  Subsequent S24 to S27 are the same as those in the first embodiment. That is, based on the result of the voltage level determination means 334, the control mode switching means 335 switches the control mode of the flywheel motor generator 32 (S24, S25), and the control command execution means 338 is generated by the voltage control means 337. Based on the control command (S26), the drive of the flywheel motor generator 32 is controlled (S27).

In addition, this invention is not limited to the said embodiment, Including other structures etc. which can achieve the objective of this invention, the deformation | transformation etc. which are shown below are also contained in this invention.
For example, in the embodiment, the control gain setting unit 336 and the voltage control unit 337 are voltage control circuits, but may be those using a microprocessor. In this case, as the control gain setting means 336, the control gain is selected from patterns stored in advance based on the determination result of the voltage level determination means, or the calculation is based on the deviation used in the determination of the voltage level determination means. Things to do are conceivable.

  The best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this. That is, the invention has been illustrated and described with particular reference to certain specific embodiments, but details of the above-described embodiments have been set forth without departing from the scope and spirit of the invention. In this configuration, those skilled in the art can make various modifications.

  The present invention is applicable to any construction machine equipped with a revolving structure driven by an electric motor.

1 is a block diagram showing an entire construction machine according to a first embodiment of the present invention. The figure which shows the connection relation between each control apparatus and DC line which comprise the construction machine which concerns on the said 1st Embodiment. The figure which shows the output state at the time of control of the turning body of the construction machine which concerns on the said 1st Embodiment. The block diagram which shows the structure of the flywheel control apparatus which concerns on the said 1st Embodiment. The figure for demonstrating the voltage control gain of the said 1st Embodiment. The figure for demonstrating the voltage control gain of the said 1st Embodiment. The flowchart which shows the control flow of the flywheel control apparatus which concerns on the said 1st Embodiment. The block diagram which shows the structure of the flywheel control apparatus which concerns on 2nd Embodiment of this invention. The flowchart which shows the control flow of the flywheel control apparatus which concerns on the said 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric turning shovel (construction machine), 4 ... Motor generator, 9 ... Turning body, 21 ... Turning electric motor, 30 ... Energy storage device, 31 ... Flywheel, 32 ... Flywheel motor generator, 33 ... Flywheel control Device: 42 ... Voltage sensor (line voltage detection means), 333 ... Target voltage storage means, 334 ... Voltage level determination means, 335 ... Control mode switching means, 336 ... Control gain setting means, 337 ... Voltage control means, 339 ... Power generation Voltage output means.

Claims (5)

In the energy storage device (30) of the construction machine (1),
A flywheel electric motor connected to a common power line together with a swing motor (21) for driving the swing body (9) of the construction machine (1) and a motor generator (4) for supplying electric power to the swing motor (21). A generator (32);
A flywheel (31) coupled to the flywheel motor generator (32) for storing energy;
A flywheel control device (33) for controlling the flywheel motor generator (32),
The flywheel control device (33)
Voltage level determination means (334) for determining whether a control voltage value to be controlled by the flywheel motor generator (32) is equal to or higher than a target voltage value;
Control mode switching means (335) for switching the control mode of the flywheel motor generator (32) based on the determination result of the voltage level determination means (334),
When it is determined by the voltage level determination means (334) that the control voltage value is greater than or equal to the target voltage value, the control mode switching means (335) sets the control mode of the flywheel motor generator (32). By switching to an electric motor and rotating the flywheel (31), energy is accumulated in the flywheel (31),
When it is determined by the voltage level determination means (334) that the control voltage value is lower than the target voltage value, the control mode switching means (335) sets the control mode of the flywheel motor generator (32) to the generator. The energy storage device (30) of the construction machine (1), wherein the energy storage device (30) is switched to generate electric power with the rotational energy of the flywheel (31) and supply current to the power line. In the energy storage device (30) of the construction machine (1) according to claim 1,
The flywheel control device (33) includes target voltage storage means (333) for storing the target voltage value,
The voltage level determination means (334) detects a predetermined voltage value acquired from the target voltage storage means (333) and a line voltage of the power supply line, and outputs a line voltage detection means (42) as the control voltage value. The energy storage device (30) of the construction machine (1), characterized in that the line voltage value obtained from (1) is compared. In the energy storage device (30) of the construction machine (1) according to claim 1,
The flywheel control device (33) includes power generation voltage output means (339) for outputting the power generation voltage of the flywheel motor generator (32) as the control voltage value.
The voltage level determination means (334) calculates a power generation voltage value of the motor generator (4) and a power generation voltage value of the flywheel motor generator (32) acquired from the power generation voltage output means (339). An energy storage device (30) for a construction machine (1) characterized in that it is compared. In the energy storage device (30) of the construction machine (1) according to claim 2 or 3, the flywheel control device (33)
Control gain setting means (336) in which a control gain determined by the capacity of the motor generator (4) and the capacity of the flywheel motor generator (32) is set;
Voltage control means (337) for controlling the control voltage value,
The voltage control means (337) supplies, to the flywheel motor / generator (32), a current determined according to a deviation between the control voltage value and the target voltage value according to the control gain setting. An energy storage device (30) for a construction machine (1), wherein energy is stored in a wheel (31) or supplied to the power supply line from the flywheel motor generator (32). In the energy storage device (30) of the construction machine (1) according to claim 4,
A current supplied from the power line to the motor generator (4) when the control voltage value is equal to or higher than the target voltage value, and a current supplied from the power line to the flywheel motor generator (32). The current supplied to the power line by the motor generator (4) when the control voltage value is lower than the target voltage value, and the flywheel motor generator (32) The ratio of the current supplied to the line is determined by the ratio of the control gain of the motor generator (4) and the control gain of the flywheel motor generator (32). Construction machine (1 ) Energy storage device (30).

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