JP6640650B2 - Construction machinery - Google Patents

Description

  The present invention relates to a construction machine equipped with an electric motor, a power storage device, and a hydraulic pump.

  In general, a hybrid construction machine including an electric motor mechanically coupled to an engine and a hydraulic pump, and a power storage device such as a lithium ion battery or a capacitor is known. In such a hybrid construction machine, the electric motor plays a role of charging the power storage device with the power generated by the driving force of the engine or assisting the engine by powering using the power of the power storage device.

  In addition, a power storage device such as a lithium ion battery needs to control voltage, current, temperature, and the like in order to prevent primary performance degradation and damage. For this reason, the power storage device is provided with a monitoring device for monitoring its state, and the monitoring device controls the voltage and the like so as not to deviate from a predetermined usage range (for example, see Patent Documents 1 and 2).

  Patent Literature 1 discloses that a reversible internal resistance due to a short-time large current inside a battery and an irreversible internal resistance due to a long-time low current are calculated, and charging / discharging is stopped according to a ratio of these resistances. A configuration for preventing an increase in the target internal resistance is disclosed. Patent Document 2 discloses a configuration in which in order to suppress heat generation of a component, the current is limited using a first-order lag equation of the square value of the current, and the temperature of the component within the rated temperature is suppressed.

Japanese Patent No. 4923116 JP 2012-96812 A

  By the way, in the control method described in Patent Literature 1, charging and discharging of a battery are stopped based on a ratio between a reversible internal resistance and an irreversible internal resistance. For this reason, for example, there is a problem that it is difficult to apply to a construction machine which is highly dependent on the electric power of a battery and is based on the assumption that a steady motor output is used.

  On the other hand, in the control method described in Patent Literature 2, the limit value is switched between charging and discharging. However, basically, a single component is controlled with a single limiting value. That is, the current is merely limited based on the result of the single first-order lag equation, and a plurality of indices (such as reversible internal resistance, irreversible internal resistance, temperature, etc.) of the battery, which are calculated from the current value, There is a problem that the same target (battery or battery current) cannot be controlled by the (restriction condition).

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the related art, and an object of the present invention is to provide a construction capable of controlling the current of a power storage device according to a plurality of limiting conditions while suppressing operation stop of the power storage device. To provide a machine.

In order to solve the above problems, the present invention provides an electric motor, a power storage device electrically connected to the electric motor, a hydraulic pump driven by the electric motor, and a hydraulic device driven by hydraulic oil from the hydraulic pump. And, in the construction machine having a controller that controls the output of the power storage device, the controller has a different time constant from each other, a plurality of first-order delay calculators that perform a first-order delay calculation based on the current of the power storage device, A current control calculator that controls the current of the power storage device based on the calculation results of the plurality of first-order delay calculators , wherein the current control calculator is a time constant of the plurality of first-order delay calculators. The plurality of operations for adjusting the calculation results of the first-order lag calculators such that the steady-state value of the first-order lag calculator having a smaller time constant is smaller than the steady-state value of the first-order lag calculator having a larger time constant. A result adjuster, a maximum value selector that selects the largest one of the adjustment results from the plurality of operation result adjusters, and a current limit value of the power storage device based on an output result from the maximum value selector. And a current limit value calculation unit that calculates the current limit value .

  According to the present invention, a power storage device having a plurality of limiting conditions can be appropriately (efficiently) operated while suppressing operation stoppage.

1 is a front view illustrating a hybrid excavator according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a hydraulic system and an electric system applied to the hybrid hydraulic shovel in FIG. 1. FIG. 3 is a block diagram illustrating a configuration of a battery unit in FIG. 2. FIG. 4 is a block diagram of a configuration of the present invention mounted in the hybrid controller in FIG. 3. FIG. 9 is a characteristic diagram showing a time change of an output signal output from the first to fourth primary delay calculators when the current of the power storage device changes stepwise. FIG. 6 is a characteristic diagram showing a change over time of a ratio output from the first to fourth dividers based on the output signal shown in FIG. 5.

  Hereinafter, a hybrid hydraulic shovel will be described as an example of a construction machine according to an embodiment of the present invention with reference to the accompanying drawings.

  1 to 4 show an embodiment of the present invention. The hybrid hydraulic shovel 1 (hereinafter, hydraulic shovel 1) includes an engine 21 and a generator motor 27 (electric motor), which will be described later. The hydraulic excavator 1 is mounted on a lower traveling body 2 of a crawler type that is capable of self-traveling, a swing device 3 provided on the lower traveling body 2, and is swingably mounted on the lower traveling body 2 via the swing device 3. And a multi-joint working device 11 provided on the front side of the upper rotating body 4 for performing excavation work and the like. At this time, the lower traveling unit 2 and the upper revolving unit 4 constitute a vehicle body of the excavator 1.

  The upper swing body 4 includes a building cover 6 provided on the swing frame 5 and housing the engine 21 and the like, and a cab 7 on which an operator rides. A driver's seat (not shown) on which an operator sits is provided in the cab 7, and around the driver's seat, a traveling operation device 8 including an operation lever and an operation pedal, and a turning operation including an operation lever and the like. A device 9 and a work operation device 10 including an operation lever and the like are provided (see FIG. 2).

  Here, the operation devices 8 to 10 are provided with operation amount sensors 8A to 10A for detecting these operation amounts, respectively. These operation amount sensors 8 </ b> A to 10 </ b> A detect operation states of the vehicle body such as a traveling operation of the lower traveling body 2, a turning operation of the upper revolving body 4, a raising / lowering operation (excavation operation) of the working device 11, and the like.

  As shown in FIG. 1, the working device 11 includes, for example, a boom 11A, an arm 11B, and a bucket 11C, and a boom cylinder 11D, an arm cylinder 11E, and a bucket cylinder 11F that drive these. The boom 11A, the arm 11B, and the bucket 11C are pin-connected to each other. The working device 11 is attached to the turning frame 5 and moves up and down by extending or contracting the cylinders 11D to 11F.

  Here, the hydraulic shovel 1 includes an electric system that controls the generator motor 27 and the like, and a hydraulic system that controls the operation of the working device 11 and the like. Hereinafter, the system configuration of the excavator 1 will be described with reference to FIGS. 2 and 3.

  The engine 21 is mounted on the turning frame 5. The engine 21 is configured by an internal combustion engine such as a diesel engine, for example. As shown in FIG. 2, a hydraulic pump 23 and a generator motor 27 are mechanically connected in series on the output side of the engine 21, and the hydraulic pump 23 and the generator motor 27 are driven by the engine 21. Is done. Here, the operation of the engine 21 is controlled by an engine control unit 22 (hereinafter, referred to as ECU 22), and the ECU 22 controls the output torque, rotation, The speed (engine speed) is controlled. The maximum output of the engine 21 is smaller than the maximum power of the hydraulic pump 23, for example.

  The hydraulic pump 23 is mechanically connected to the engine 21. The hydraulic pump 23 can be driven by the torque of the engine 21 alone. The hydraulic pump 23 can also be driven by a combined torque (total torque) obtained by adding the assist torque of the generator motor 27 to the torque of the engine 21. The hydraulic pump 23 pressurizes hydraulic oil stored in a tank (not shown) and discharges the hydraulic oil as hydraulic oil to the traveling hydraulic motor 25, the swing hydraulic motor 26, the cylinders 11D to 11F of the working device 11, and the like.

  The hydraulic pump 23 is connected to a traveling hydraulic motor 25 as a hydraulic device, a swing hydraulic motor 26, and cylinders 11D to 11F via a control valve 24. These hydraulic motors 25 and 26 and cylinders 11D to 11F are driven by pressure oil from a hydraulic pump 23. The control valve 24 supplies the hydraulic oil discharged from the hydraulic pump 23 to the travel hydraulic motor 25, the swing hydraulic motor 26, and the cylinders 11D to 11F in accordance with operations on the travel operation device 8, the swing operation device 9, and the work operation device 10. Supply or discharge.

  The generator motor 27 (motor generator) is mechanically connected to the engine 21. The generator motor 27 is constituted by, for example, a synchronous motor or the like. The generator motor 27 functions as a generator using the engine 21 as a power source to supply power to the power storage device 32, and assists driving of the engine 21 and the hydraulic pump 23 by using power from the power storage device 32 as a motor as a motor. And play two roles. Therefore, the assist torque of the generator motor 27 is added to the torque of the engine 21 according to the situation, and the hydraulic pump 23 is driven by these torques. The running operation, the turning operation, the raising / lowering operation of the working device 11 and the like are performed by the hydraulic oil discharged from the hydraulic pump 23.

  As shown in FIG. 2, the generator motor 27 is connected to a pair of DC buses 29A and 29B via an inverter 28. The inverter 28 is configured using a plurality of switching elements including, for example, a transistor, an insulated gate bipolar transistor (IGBT), and the like, and ON / OFF of each switching element is controlled by a power control unit 30 (hereinafter, referred to as a PCU 30). The DC buses 29A and 29B form a pair on the positive electrode side and the negative electrode side, and a DC voltage of, for example, about several hundred volts is applied thereto.

  When the generator motor 27 generates power, the inverter 28 converts AC power from the generator motor 27 into DC power and supplies the DC power to the power storage device 32. During power running of the generator motor 27, the inverter 28 converts the DC power of the DC buses 29 </ b> A and 29 </ b> B into AC power and supplies the AC power to the generator motor 27. The PCU 30 controls on / off of each switching element of the inverter 28 based on a generator motor output command from the HCU 35 and the like. Thereby, the PCU 30 controls the generated power when the generator motor 27 generates power and the driving power during power running.

  The battery unit 31 includes a power storage device 32 made of, for example, a lithium ion secondary battery, a current sensor 33, and a battery controller 34 (hereinafter, referred to as a BC 34) (see FIG. 3). Power storage device 32 is electrically connected to generator motor 27. Specifically, power storage device 32 is connected to inverter 28 via DC buses 29A and 29B.

  The power storage device 32 charges the electric power supplied from the generator motor 27 when the generator motor 27 generates electric power, and supplies driving power to the generator motor 27 when the generator motor 27 is running (assist driving). The HCU 35 controls the charging operation and the discharging operation of the power storage device 32 based on information from the BC 34.

  The current sensor 33 is connected to, for example, a positive terminal of the power storage device 32 and detects a charging current or a discharging current of the power storage device 32. The output side of the current sensor 33 is connected to the BC 34. The current sensor 33 outputs a signal corresponding to the detected current I to the BC 34.

  The current I of the power storage device 32 is input to the BC 34 based on a signal from the current sensor 33. Further, a voltage sensor and a temperature sensor (both not shown) are connected to the BC 34, and the voltage V and the temperature T of the power storage device 32 are input. The BC 34 calculates power that can be discharged from the power storage device 32 as battery discharge power based on the current I, the voltage V, and the temperature T. Similarly, the BC 34 calculates power that can be charged in the power storage device 32 as battery charging power. The BC 34 outputs a battery storage rate (SOC), battery discharge power, battery charge power, and the like to a hybrid control unit 35 (hereinafter, referred to as HCU 35).

  In addition, the BC 34 monitors the state of the power storage device 32 based on the voltage V, the current I, the temperature T, the state of charge (SOC: State Of Charge), the degree of deterioration (SOH: State Of Health), and the like. presume. The BC 34 transmits a signal to the HCU 35 and issues an abnormality / warning when any one of these indices deviates from or is likely to deviate from the proper use range.

  The HCU 35 is configured by, for example, a microcomputer, and is electrically connected to the ECU 22, the PCU 30, the BC 34, and the MC 36 using a CAN (Controller Area Network) or the like. The MC 36 is connected to operation amount sensors 8A to 10A that detect the lever operation amounts of the operation devices 8 to 10. The MC 36 communicates with the ECU 22 and the HCU 35, and transmits various control signals to the ECU 22, the PCU 30, and the HCU 35 based on, for example, the lever operation amount, the rotation speed of the engine 21, the state of charge (SOC) of the power storage device 32, and the like. Thus, the ECU 22 controls the number of revolutions of the engine 21 and the like based on the control signal from the MC 36. Also, the HCU 35, based on the state of other hybrid devices (motors and inverters) and information on the lever operation amounts of the operating devices 8 to 10 from the MC 36, the generator motor 27, the inverter 28, and the power storage device 32, which are hybrid devices. Control.

  In addition, HCU 35 forms a controller and controls the output of power storage device 32. Specifically, the current I of the power storage device 32 is input to the HCU 35 based on a signal from the BC 34. At this time, the HCU 35 calculates a current limit value Ilim [%] for limiting the current I based on the current I. If the current I does not need to be limited, the current limit value Ilim becomes 100%. On the other hand, when the current I needs to be limited, the current limit value Ilim becomes a value lower than 100% (Ilim <100) according to the degree of the restriction. HCU 35 controls charging and discharging of power storage device 32 using PCU 30 and inverter 28 such that current I becomes smaller than current limit value Ilim.

  Next, a specific configuration of the present invention mounted on the HCU 35 will be described. As shown in FIG. 4, the HCU 35 includes a square calculator 41, first to fourth primary delay calculators 42 to 45, and a current control calculator 46.

The input side of the square calculator 41 is connected to the BC 34, and the current I detected by the current sensor 33 is input. The square calculator 41 calculates a current calculation value I ² obtained by squaring the current I. At this time, the current calculation value I ² becomes a positive value regardless of whether the charging or discharging current I is input. Square calculation unit 41 outputs a current operation value I ² to the first to fourth first-order lag calculator 42-45.

The first primary delay calculator 42 calculates the first-order lag response of the current calculation value I ^2, and outputs an output signal Y1 (t). The first primary delay calculator 42 has a predetermined time constant T1 and constitutes a low-pass filter. The first primary delay calculator 42 has a transfer function H1 (s) shown in the following equation (1).

The second to fourth first-order lag calculators 43 to 45 have substantially the same configuration as the first first-order lag calculator 42. Therefore, the second to fourth first-order lag calculator 43 to 45, calculates a first-order lag response of the current calculation value I ^2, and outputs an output signal Y2 (t) ~Y4 (t) . The second to fourth primary delay calculators 43 to 45 have predetermined time constants T2 to T4 and constitute a low-pass filter. The second to fourth first-order lag calculators 43 to 45 have transfer functions H2 (s) to H4 (s) represented by the following equations 2 to 4, respectively.

  Here, the time constants T1 to T4 are set to different values. Specifically, the time constants T1 to T4 satisfy the relationship shown in the following equation (5). That is, the time constants T1 to T4 are sequentially increased. Therefore, the time constant T2 is larger than the time constant T1, the time constant T3 is larger than the time constant T2, and the time constant T4 is larger than the time constant T3.

  For this reason, among the first to fourth primary delay arithmetic units 42 to 45, the first primary delay arithmetic unit 42 has the highest cutoff frequency. For this reason, even when the current I changes sharply in a short time, the output signal Y1 (t) of the first primary delay calculator 42 changes. On the other hand, among the first to fourth primary delay arithmetic units 42 to 45, the fourth primary delay arithmetic unit 45 has the lowest cutoff frequency. For this reason, when the current I changes sharply in a short time, the output signal Y4 (t) of the fourth primary delay calculator 45 changes little, and when the current I changes slowly in a long time, the output signal Y4 (t) changes. Y4 (t) changes.

  The cutoff frequency of the second primary delay calculator 43 is lower than the cutoff frequency of the first primary delay calculator 42 and higher than the cutoff frequency of the fourth primary delay calculator 45. For this reason, the output signal Y2 (t) of the second primary delay calculator 43 has intermediate characteristics between the output signal Y1 (t) and the output signal Y4 (t). Therefore, for example, when the current I increases stepwise, the output signal Y2 (t) rises slower than the output signal Y1 (t) and rises earlier than the output signal Y4 (t).

  The cutoff frequency of the third primary delay calculator 44 is lower than the cutoff frequency of the second primary delay calculator 43 and higher than the cutoff frequency of the fourth primary delay calculator 45. Therefore, the output signal Y3 (t) of the third primary delay calculator 44 has an intermediate characteristic between the output signal Y2 (t) and the output signal Y4 (t). Therefore, for example, when the current I increases stepwise, the output signal Y3 (t) rises slower than the output signal Y2 (t) and rises earlier than the output signal Y4 (t).

  In the equations (1) to (4), coefficients K1 to K4 indicate the gain of the pass band. These coefficients K1 to K4 are appropriately set according to specifications and the like. The coefficients K1 to K4 may have the same value or different values. The coefficients K1 to K4 are set to 1, for example, as the same value.

  Current control calculator 46 controls the charge / discharge current of power storage device 32 based on the calculation results of first to fourth primary delay calculators 42 to 45. More specifically, the current control calculator 46 controls the charge / discharge current based on the output signals Y1 (t) to Y4 (t) from the first to fourth primary delay calculators 42 to 45. The current limit value Ilim [%] is output. The current control calculator 46 includes first to fourth dividers 46A to 46D, a maximum value selector 46E, and a current limit value calculator 46F.

  The first to fourth dividers 46A to 46D constitute an operation result adjuster. In the first to fourth dividers 46A to 46D, the steady-state value of the first-order lag calculator having the smaller time constant among the first-order lag calculators 42 to 45 is smaller than the steady-state value of the first-order lag calculator having the larger time constant. The output signals Y1 (t) to Y4 (t) of the first-order lag calculators 42 to 45 are adjusted so as to be as follows.

  The first divider 46A divides the output signal Y1 (t) by a predetermined threshold C1. The first divider 46A calculates a first ratio R1 (R1 = Y1 / C1) as a ratio of the output signal Y1 (t) to the threshold C1.

  The second divider 46B divides the output signal Y2 (t) by a predetermined threshold C2. The second divider 46B calculates a second ratio R2 (R2 = Y2 / C2) as a ratio of the output signal Y2 (t) to the threshold C2.

  The third divider 46C divides the output signal Y3 (t) by a predetermined threshold C3. The third divider 46C calculates a third ratio R3 (R3 = Y3 / C3) as a ratio of the output signal Y3 (t) to the threshold C3.

  The fourth divider 46D divides the output signal Y4 (t) by a predetermined threshold C4. The fourth divider 46D calculates a fourth ratio R4 (R4 = Y4 / C4) as a ratio of the output signal Y4 (t) to the threshold C4.

  The first to fourth dividers 46A to 46D output the ratios R1 to R4 to the maximum value selector 46E. Here, the thresholds C1 to C4 are set so as to satisfy the relationship shown in the following equation (6). Therefore, as the time constants T1 to T4 of the first-order lag calculators 42 to 45 that calculate the output signals Y1 (t) to Y4 (t) increase, the coefficients corresponding to the output signals Y1 (t) to Y4 (t) increase. The ratio between K1 to K4 and thresholds C1 to C4 is small. Therefore, K1 / C1 is the smallest and K4 / C4 is the largest.

  The maximum value selector 46E selects the largest maximum ratio Rmax among the first to fourth ratios R1 to R4. At this time, in the dividers 46A to 46D, the ratios of the coefficients K1 to K4 and the thresholds C1 to C4 are set to different values according to the time constants T1 to T4 of the first-order lag calculators 42 to 45. Therefore, for example, when the current I sharply increases in a short time, the output signal Y1 (t) becomes larger than the output signals Y2 (t) to Y4 (t) earlier. As a result, immediately after the current I increases, the ratio R1 output from the first divider 46A tends to be higher than the other ratios R2 to R4.

  On the other hand, for example, when the current I gradually increases over a long period of time, the output signals Y1 (t) to Y4 (t) all gradually increase. In this case, since K4 / C4 is the largest in the equation (6), after a long time, the ratio R4 output from the fourth divider 46D is smaller than the other ratios R1 to R3. Tends to be larger.

  As described above, the magnitude relationship of the first to fourth ratios R1 to R4 differs depending on the current change ratio, the elapsed time, and the like. Therefore, the maximum value selector 46E can extract an element (component) that needs to limit the current I by selecting the maximum ratio Rmax among the first to fourth ratios R1 to R4.

  The current limit value calculator 46F outputs a current limit value Ilim [%] for limiting the charge / discharge current based on the maximum ratio Rmax. The current limit value Ilim [%] indicates a rate of decrease (decrease rate) with respect to this reference value, with the charge / discharge current allowed at normal times as a reference value (100%). The current limit value calculator 46F calculates the current limit value Ilim from the maximum ratio Rmax based on the table 47 shown in FIG.

  When the maximum ratio Rmax is equal to or less than a predetermined lower limit (for example, Rmax ≦ 0.8), the current limit value calculation unit 46F sets the current limit value Ilim to the same value as in the normal state (Ilim = 100%). When the maximum ratio Rmax is larger than the predetermined lower limit and smaller than the upper limit (for example, 0.8 <Rmax <1), the current limit value calculator 46F responds to the difference between the maximum ratio Rmax and the lower limit. Thus, the current limit value Ilim is made lower than usual (0% <Ilim <100%). When the maximum ratio Rmax reaches a predetermined upper limit value (for example, Rmax = 1), the current limit value calculating unit 46F sets the current limit value Ilim to a value at which charging / discharging is stopped (Ilim = 0%). In this way, the current limit value Ilim is gradually reduced as the maximum ratio Rmax approaches the upper limit value. For this reason, stoppage of charging / discharging can be suppressed as compared with the case where the charging / discharging current is controlled in two states of permission and inhibition. Note that the lower limit, the upper limit, and the rate at which the current limit value Ilim decreases are not limited to those illustrated above, but are appropriately set according to the specifications of the power storage device 32 and the like.

  HCU 35 controls charging / discharging current I of power storage device 32 so as not to exceed current limit value Ilim output from current limit value calculation unit 46F. That is, the HCU 35 controls the current I so that the maximum ratio Rmax does not exceed the upper limit. As a result, the HCU 35 controls the engine 21 and the generator motor 27 in consideration of, for example, a decrease in power supply from the power storage device 32 due to the current limit value Ilim.

  The hydraulic shovel 1 according to the present embodiment has the above-described configuration. Next, the control of the current I of the power storage device 32 by the HCU 35 will be described with reference to FIGS. 4 to 6. FIGS. 5 and 6 show a case where the current I increases stepwise from the start time ts, and the current I rises from 0 A to a predetermined value (for example, 150 A) that can be used in normal times. In the actual battery unit 31, when a predetermined time (for example, several tens seconds to several minutes) elapses from the start time ts, the current I is limited by the HCU 35 and decreases. 5 and 6 show a virtual case where the current I is not limited.

  As shown in FIG. 5, when the current I increases stepwise at the start time ts, the output signals Y1 (t) to Y4 (t) output from the first-order lag calculators 42 to 45 all increase. At this time, the first-order delay calculators 42 to 45 of the HCU 35 have different time constants T1 to T4. For this reason, in the transient state immediately after the increase of the current I, the increase rates of the output signals Y1 (t) to Y4 (t) differ from each other according to the time constants T1 to T4. For example, the time constant T1 of the first primary delay calculator 42 is smaller than the other time constants T2 to T4, so that the output signal Y1 (t) in the transient state is different from the other output signals Y2 (t) to Y4. It increases earlier than (t). Conversely, the time constant T4 of the fourth primary delay calculator 45 is larger than the other time constants T1 to T3, so that the increase of the output signal Y4 (t) increases the other output signals Y1 (t) to Y3. Delay compared to (t).

  In this case, the four dividers 46A to 46D make the steady value of the output signal Y1 (t) smaller than the steady values of the other output signals Y2 (t) to Y4 (t). The signal Y1 (t) is larger than the other output signals Y2 (t) to Y4 (t). For this reason, as shown in FIG. 6, immediately after the current I increases, the ratio R1 output from the first divider 46A becomes larger than the other ratios R2 to R4. As a result, the current limit value calculator 46F calculates the current limit value Ilim for the current I in the transient state based on the ratio R1 selected by the maximum value selector 46E.

  On the other hand, as shown in FIG. 5, in a steady state in which the current I converges to a predetermined value, if the coefficients K1 to K4 have the same value, the output signals Y1 (t) of the first-order lag calculators 42 to 45 ＹY4 (t) converge to substantially the same value. At this time, the dividers 46A to 46D output the signal Y1 (t) so that the steady-state value of the first-order lag calculator 42 having a small time constant T1 is smaller than the steady-state values of the other first-order lag calculators 43 to 45. ) To Y4 (t) are adjusted to output ratios R1 to R4. For this reason, as shown in FIG. 6, in a steady state where a sufficient time has elapsed since the increase of the current I, the time constant T3 is larger than the time constants T1 and T2, so that the output signal Y3 ( The ratio R3 obtained by adjusting t) becomes larger than the ratios R1 and R2. Similarly, when the current I is further continued to flow, the ratio R4 eventually exceeds the ratio R3. As a result, the current limit value calculator 46F calculates the current limit value Ilim for the steady state current I based on the ratios R3 and R4 selected by the maximum value selector 46E.

  As described above, when the current I changes rapidly in a short time and when the current I changes slowly in a long time, the current limit is determined based on different output signals Y1 (t) to Y4 (t). The value Ilim can be calculated. As a result, the same target (battery or battery current) is controlled by a plurality of indices (restriction conditions) such as a reversible internal resistance, an irreversible internal resistance, and a temperature of the power storage device 32, which are calculated from the current I. be able to.

  Thus, according to the present embodiment, the HCU 35 has four different time constants T1 to T4, and four first-order delay calculators 42 to 45 that perform the first-order delay calculation based on the charging / discharging current of the power storage device 32. And a current control calculator 46 for controlling the current I of the power storage device 32 based on the calculation results of the four primary delay calculators 42 to 45. For this reason, since the first-order lag calculators 42 to 45 output the output signals Y1 (t) to Y4 (t) having different responsiveness from each other, the current control calculator 46 is based on a plurality of conditions having different responsiveness. , The current I of the power storage device 32 can be controlled. Therefore, the same object (battery or battery current) is controlled by a plurality of indices (restriction conditions) such as reversible internal resistance, irreversible internal resistance, and temperature of the power storage device 32, which are calculated from the current I. Can be. As a result, the current I of the power storage device 32 can be controlled according to a plurality of limiting conditions while suppressing the operation stop of the power storage device 32, so that the performance of the power storage device 32 can be appropriately prevented from deteriorating. Can be used.

  The current control calculator 46 includes four dividers 46A to 46D (calculation result adjusters), a maximum value selector 46E, and a current limit value calculator 46F. At this time, the four dividers 46A to 46D change the steady-state value of the first-order lag calculator having the smaller time constant among the four first-order lag calculators 42 to 45 into the steady-state value of the first-order lag calculator having the larger time constant. The output signals Y1 (t) to Y4 (t) of the first-order lag calculators 42 to 45 are adjusted so as to be smaller.

  Therefore, in the steady state, the output signals Y1 (t) to Y4 (t) of the first-order lag calculators 42 to 45 are close to each other, so that the output signal Y4 (t) of the first-order lag calculator 45 having a large time constant T4. ) Is larger than the other ratios R1 to R3. On the other hand, in the transient state, the output signal Y1 (t) of the first-order lag calculator 42 having a small time constant T1 is larger than the other output signals Y2 (t) to Y4 (t). Is larger than the other ratios R2 to R4.

  At this time, the maximum value selector 46E selects the maximum ratio Rmax among the ratios R1 to R4 (adjustment results) in which the output signals Y1 (t) to Y4 (t) are adjusted by the four dividers 46A to 46D. . Accordingly, the maximum value selector 46E can select different ratios R1 to R4 depending on whether the current I changes abruptly or when the current I changes gradually, and it is necessary to limit the current I. Elements (components) can be extracted.

  Further, current limit value calculating section 46F calculates current limit value Ilim of power storage device 32 based on maximum ratio Rmax (output result) from maximum value selector 46E. As a result, the current I can be limited in accordance with the rate of change of the current, the elapsed time, and the like.

  As a result, when the current I changes abruptly in a short time, the current control calculator 46 changes the ratio R1 of the calculation result (output signal Y1 (t)) of the primary delay calculator 42 having a small time constant T1. When approaching the upper limit value, current I of power storage device 32 can be limited. On the other hand, when the current I gradually changes over a long period of time, the current control calculator 46 sets the upper limit of the ratio R4 of the calculation result (output signal Y4 (t)) of the primary delay calculator 45 having a large time constant T4. When approaching the value, current I of power storage device 32 can be limited.

  In the above-described embodiment, the current control calculator 46 is configured to include the four dividers 46A to 46D, the maximum value selector 46E, and the current limit value calculator 46F. The present invention is not limited to this. For example, when the coefficients K1 to K4 (gains) of the first-order lag calculators 42 to 45 increase as the time constants T1 to T4 increase, the dividers 46A to 46D are omitted. Is also good.

  In the above embodiment, the dividers 46A to 46D are used as operation result adjusters. The present invention is not limited to this. Each primary delay computing unit is configured such that the primary value of the primary delay computing unit having a small time constant is smaller than the stationary value of the primary delay computing unit having a large time constant. Any device that adjusts the operation result of the delay operation device may be used. For example, a multiplier that multiplies a coefficient may be used.

  In the above-described embodiment, the HCU 35 is configured to include the four primary delay arithmetic units 42 to 45, but may be configured to include two or three primary delay arithmetic units, and may be configured to include five or more primary delay arithmetic units. It is good also as composition provided with a container.

  In the above embodiment, the HCU 35 calculates the current limit value Ilim for controlling the power storage device 32. However, the BC 34 may calculate the current limit value Ilim. The HCU 35 includes the square calculator 41, the first to fourth first-order lag calculators 42 to 45, and the current control calculator 46. Of these, the former part (for example, the square calculator 41) ) May be provided in the BC 34, and the HCU 35 may be provided in the HCU 35 with subsequent stages (for example, the first-order lag calculators 42 to 45 and the current control calculator 46). Further, the HCU 35 and the BC 34 may be integrated to form a single controller.

  In the above-described embodiment, the maximum output of the engine 21 is smaller than the maximum power of the hydraulic pump 23. However, the maximum output of the engine 21 is appropriately set according to the specifications of the hydraulic excavator 1. Therefore, the maximum output of the engine 21 may be about the same as the maximum power of the hydraulic pump 23, or may be larger than the maximum power of the hydraulic pump 23.

  In the above-described embodiment, the case where a lithium ion secondary battery is used as the power storage device 32 has been described as an example. However, another secondary battery (for example, a nickel cadmium battery, a nickel hydride battery) capable of supplying necessary power is described. Or a capacitor may be used. Further, a step-up / step-down device such as a DC-DC converter may be provided between the power storage device and the DC bus.

  In the above-described embodiment, the crawler type hybrid hydraulic excavator 1 has been described as an example of the construction machine. The present invention is not limited to this. For example, various hybrid construction machines including an electric motor connected to an engine and a hydraulic pump and a power storage device, such as a wheel-type hybrid hydraulic excavator, a hybrid wheel loader, a lift truck, and the like. Applicable. The present invention is also applicable to an electric construction machine in which an engine is omitted and a hydraulic pump is driven only by an electric motor.

1 hybrid hydraulic excavator (construction equipment)
11 work equipment 11D boom cylinder (hydraulic device)
11E Arm cylinder (hydraulic device)
11F Bucket cylinder (hydraulic device)
21 engine 23 hydraulic pump 25 traveling hydraulic motor (hydraulic device)
26 Rotating hydraulic motor (hydraulic device)
27 Generator motor (motor)
32 Power storage device 33 Current sensor 34 Battery controller 35 Hybrid controller (controller)
42-45 First-order lag calculator 46 Current control calculator 46A-46D Divider (calculation result adjuster)
46E maximum value selector 46F current limit value calculator

Claims (2)

Electric motor,
A power storage device electrically connected to the electric motor,
A hydraulic pump driven by the electric motor,
A hydraulic device driven by pressure oil from the hydraulic pump,
A construction machine having a controller that controls an output of the power storage device;
The controller is
A plurality of primary delay calculators having different time constants and performing a primary delay calculation based on the current of the power storage device;
A current control calculator that controls a current of the power storage device based on a calculation result of the plurality of primary delay calculators ,
The current control calculator is such that, among the plurality of first-order delay calculators, the steady-state value of the first-order delay calculator having a smaller time constant is smaller than the steady-state value of the first-order delay calculator having a larger time constant. A plurality of operation result adjusters for adjusting the operation result of the primary delay operation unit;
A maximum value selector for selecting the largest one of the adjustment results by the plurality of operation result adjusters,
A construction machine , comprising: a current limit value calculator that calculates a current limit value of the power storage device based on an output result from the maximum value selector . Further comprising an engine mechanically connected to the electric motor,
The construction machine according to claim 1, wherein the hydraulic pump is driven by the electric motor and the engine.

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