JP2017206865A - Construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control an electric current of a power storage device in accordance with a plurality of limiting conditions while restraining a shutdown of the power storage device.SOLUTION: An HCU 35 comprises four primary delay computation units 42-45 having mutually different time constants T1-T4 and executing primary delay computation based on an electric current I of a power storage device 32 and an electric current control computation unit 46 for limiting the electric current I of the power storage device 32 on the basis of output signals Y1(t)-Y4(t) from the four primary delay computation units 42-45. The electric current control computation unit 46 comprises four subtracters 46A-46D for adjusting the output signals Y1(t)-Y4(t) from the primary delay computation units 42-45, a maximum value selector 46E for selecting a maximum ratio Rmax among the ratios R1-R4 output from the subtracters 46A-46D, and an electric current limiting value calculation unit 46F for calculating an electric current limiting value Ilim of the power storage device 32 on the basis of the maximum ratio Rmax.SELECTED DRAWING: Figure 4

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 is known that includes 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. 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 that monitors its state, and the monitoring device controls the voltage and the like so as not to deviate from a predetermined use range (see, for example, Patent Documents 1 and 2).

  Patent Document 1 calculates a reversible internal resistance caused by a large current for a short time inside a battery and an irreversible internal resistance caused by a low current for a long time. A configuration for preventing an increase in the internal resistance is disclosed. Patent Document 2 discloses a configuration in which a current is limited using a first-order lag equation of a square value of current to suppress component heat generation, and a component temperature within a rated temperature can be suppressed.

Japanese Patent No. 4923116 JP 2012-96712 A

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

  On the other hand, in the control system described in Patent Document 2, the limit value is switched between charging and discharging, but basically a single component is controlled with a single limit value. In other words, the current is limited only based on the result of a single first-order lag equation, and a plurality of indicators such as reversible internal resistance, irreversible internal resistance, temperature, and the like obtained by calculation from the current value ( There is a problem that the same object (battery or battery current) cannot be controlled under the (restriction condition).

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is a construction capable of controlling the current of a power storage device according to a plurality of restriction conditions while suppressing the 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 pressure oil from the hydraulic pump And a controller that controls the output of the power storage device, wherein the controller has a plurality of first-order lag calculators having different time constants and performing a first-order lag calculation based on the current of the power storage device; And a current control calculator that controls the current of the power storage device based on the calculation results of the plurality of first-order lag calculators.

  According to the present invention, it is possible to appropriately (efficiently) operate a power storage device having a plurality of restriction conditions while suppressing operation stop.

1 is a front view showing a hybrid excavator according to an embodiment of the present invention. It is a block diagram which shows the hydraulic system and electric system which are applied to the hybrid hydraulic shovel in FIG. It is a block diagram which shows the structure of the battery unit in FIG. It is the figure which embodied the structure of this invention mounted in the hybrid controller in FIG. 3 with the block diagram. It is a characteristic diagram which shows the time change of the output signal output from the 1st thru | or 4th first order lag calculator when the electric current of an electrical storage apparatus changes in step shape. FIG. 6 is a characteristic diagram showing a change over time in the ratio output from the first to fourth dividers based on the output signal shown in FIG. 5.

  Hereinafter, a hybrid hydraulic excavator 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 excavator 1 (hereinafter referred to as the hydraulic excavator 1) includes an engine 21 and a generator motor 27 (an electric motor) which will be described later. The hydraulic excavator 1 is mounted on a crawler type lower traveling body 2 capable of self-running, a turning device 3 provided on the lower traveling body 2, and turnable on the lower traveling body 2 via the turning device 3. The upper swing body 4 and a multi-joint structure working device 11 that is provided on the front side of the upper swing body 4 and performs excavation work or the like. At this time, the lower traveling body 2 and the upper swing body 4 constitute a vehicle body of the hydraulic 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 gets on. A driver's seat (not shown) on which an operator is seated is provided in the cab 7, and around the driver's seat, a traveling operation device 8 including an operation lever, an operation pedal and the like, 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 8A to 10A detect an operation state of the vehicle body such as a traveling operation of the lower traveling body 2, a turning operation of the upper revolving body 4, an uplifting operation (excavation operation) of the work device 11, and the like.

  As shown in FIG. 1, the work 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-coupled to each other. The work device 11 is attached to the revolving frame 5 and moves up and down by extending or contracting the cylinders 11D to 11F.

  Here, the hydraulic excavator 1 is equipped with an electric system that controls the generator motor 27 and the like, and a hydraulic system that controls the operation of the work device 11 and the like. Hereinafter, a 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 constituted by an internal combustion engine such as a diesel engine. 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. 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). The ECU 22 is configured to output and Controls speed (engine speed), etc. Note that 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 pressure 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 via a control valve 24 to a traveling hydraulic motor 25, a turning hydraulic motor 26, and cylinders 11D to 11F as hydraulic devices. These hydraulic motors 25 and 26 and the cylinders 11 </ b> D to 11 </ b> F are driven by pressure oil from the hydraulic pump 23. The control valve 24 sends the pressure 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 response to operations on the travel operation device 8, the turning 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. The generator motor 27 acts as a generator using the engine 21 as a power source to supply power to the power storage device 32, and acts as a motor using the power from the power storage device 32 as a power source to assist in driving the engine 21 and the hydraulic pump 23. It plays two roles with power running. Therefore, the assist torque of the generator motor 27 is added to the torque of the engine 21 depending on the situation, and the hydraulic pump 23 is driven by these torques. The hydraulic oil discharged from the hydraulic pump 23 performs a traveling operation, a turning operation of the vehicle, a lifting / lowering operation of the work device 11, and the like.

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

  During power generation by the generator motor 27, the inverter 28 converts AC power from the generator motor 27 into DC power and supplies it 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. Then, the PCU 30 controls on / off of each switching element of the inverter 28 based on a generator motor output command or the like from the HCU 35. Thereby, the PCU 30 controls the generated power when the generator motor 27 generates power and the drive power when powering.

  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 BC 34) (see FIG. 3). The power storage device 32 is electrically connected to the 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 power supplied from the generator motor 27 when the generator motor 27 generates power, and supplies drive power to the generator motor 27 when the generator motor 27 is in powering (at the time of assist drive). The power storage device 32 is controlled to be charged or discharged by the HCU 35 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 charge current or a discharge 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.

  Based on the signal from the current sensor 33, the current I of the power storage device 32 is input to the BC 34. Further, a voltage sensor and a temperature sensor (both not shown) are connected to BC 34, and voltage V and temperature T of power storage device 32 are input to BC 34. Based on the current I, voltage V, and temperature T, the BC 34 calculates power that can be discharged from the power storage device 32 as battery discharge power. 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 to this, the BC 34 monitors the state of the power storage device 32 based on the voltage V, current I, temperature T, power storage rate (SOC: State Of Charge), degree of deterioration (SOH: State Of Health), and the like. presume. The BC 34 transmits a signal to the HCU 35 to issue an abnormality / warning when any of the indicators of the plurality of elements deviates from or is likely to deviate from the proper use range.

  The HCU 35 is configured by a microcomputer, for example, 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. Further, the MC 36 is connected to operation amount sensors 8A to 10A for detecting 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 rotational speed of the engine 21, the storage rate (SOC) of the power storage device 32, and the like. Thereby, ECU22 controls the rotation speed etc. of the engine 21 based on the control signal from MC36. Further, the HCU 35 is based on information on the state of other hybrid devices (motors, inverters) and lever operation amounts of the operation 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. To control.

  In addition to this, the HCU 35 constitutes a controller and controls the output of the power storage device 32. Specifically, the HCU 35 receives the current I of the power storage device 32 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. When the current I is not limited, the current limit value Ilim is 100%. On the other hand, when it is necessary to limit the current I, the current limit value Ilim becomes a value lower than 100% (Ilim <100) according to the degree of limitation. The HCU 35 controls charging and discharging of the power storage device 32 using the PCU 30 and the inverter 28 so that the current I becomes smaller than the 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 square computing unit 41 has an input side connected to the BC 34 and receives the current I detected by the current sensor 33. The square calculator 41 calculates a current calculation value I ² obtained by squaring the current I. At this time, the calculated current value I ² is a positive value regardless of whether the current I for charging or discharging is input. The square calculator 41 outputs the current calculation value I ² to the first to fourth primary delay calculators 42 to 45.

The first primary delay calculator 42 calculates a primary delay 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 first-order lag calculator 42 has a transfer function H1 (s) expressed by the following equation (1).

The second to fourth primary delay calculators 43 to 45 are also configured in substantially the same manner as the first primary delay calculator 42. Therefore, the second to fourth primary delay calculators 43 to 45 calculate the primary delay response of the current calculation value I ² and output the output signals Y2 (t) to Y4 (t). The second to fourth first-order lag calculators 43 to 45 have predetermined time constants T2 to T4, and constitute a low-pass filter. The second to fourth primary delay calculators 43 to 45 have transfer functions H2 (s) to H4 (s) shown in 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 calculators 42 to 45, the first primary delay calculator 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 calculators 42 to 45, the fourth primary delay calculator 45 has the lowest cutoff frequency. For this reason, when the current I changes steeply in a short time, the output signal Y4 (t) of the fourth first-order lag calculator 45 is small, and when the current I changes slowly in a long time, the output signal 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. Therefore, the output signal Y2 (t) of the second first-order lag calculator 43 has an intermediate characteristic 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 later 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 first-order lag 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 later than the output signal Y2 (t) and rises earlier than the output signal Y4 (t).

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

  The current control calculator 46 controls the charge / discharge current of the power storage device 32 based on the calculation results of the first to fourth primary delay calculators 42 to 45. Specifically, the current control calculator 46 is for limiting 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 a small 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 a large time constant. Thus, the output signals Y1 (t) to Y4 (t) of the first-order lag calculators 42 to 45 are adjusted.

  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 the 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 the 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 the 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 the 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 threshold values C1 to C4 are set so as to satisfy the relationship shown in the following equation (6). Therefore, the coefficients corresponding to the output signals Y1 (t) to Y4 (t) increase 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 ratio between K1 to K4 and threshold values 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 suddenly increases in a short time, the output signal Y1 (t) becomes larger than the output signals Y2 (t) to Y4 (t). Thereby, immediately after the current I increases, the ratio R1 output from the first divider 46A tends to be larger than the other ratios R2 to R4.

  On the other hand, for example, when the current I increases slowly over a long time, the output signals Y1 (t) to Y4 (t) all increase gently. In this case, since K4 / C4 is the largest in the equation (6), the ratio R4 output from the fourth divider 46D is longer than the other ratios R1 to R3 after a long time. There is a tendency to grow.

  Thus, the magnitude relationship of the first to fourth ratios R1 to R4 varies depending on the rate of current change, the passage of time, and the like. Therefore, the maximum value selector 46E can extract an element (component) that needs to be limited by the current I by selecting the maximum ratio Rmax from the first to fourth ratios R1 to R4.

  The current limit value calculation unit 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 the rate of decrease (decrease rate) with respect to this reference value, with the charge / discharge current allowed at normal times as the reference value (100%). The current limit value calculation unit 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 value (for example, Rmax ≦ 0.8), the current limit value calculation unit 46F sets the current limit value Ilim to the same value as in normal time (Ilim = 100%). When the maximum ratio Rmax is larger than the predetermined lower limit value and smaller than the upper limit value (for example, 0.8 <Rmax <1), the current limit value calculating unit 46F responds to the difference between the maximum ratio Rmax and the lower limit value. Thus, the current limit value Ilim is lowered from the normal time (0% <Ilim <100%). Then, the current limit value calculation unit 46F has a value (Ilim = 0%) at which the current limit value Ilim stops charging / discharging when the maximum ratio Rmax reaches a predetermined upper limit value (for example, Rmax = 1). As described above, the current limit value Ilim is gradually decreased as the maximum ratio Rmax approaches the upper limit value. For this reason, the stop of charging / discharging can be suppressed compared with the case where charging / discharging electric current is controlled by permission, prohibition, and two states. In addition, the ratio etc. which the lower limit value mentioned above, an upper limit value, and the electric current limit value Ilim reduce are not limited to what was illustrated, but are suitably set according to the specification etc. of the electrical storage apparatus 32.

  The HCU 35 controls the charge / discharge current I of the power storage device 32 so as not to exceed the current limit value Ilim output from the 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 value. Accordingly, 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, for example.

  The hydraulic excavator 1 according to the present embodiment has the above-described configuration. Next, the control content of the current I of the power storage device 32 by the HCU 35 will be described with reference to FIGS. 4 to 6. 5 and 6 show a case where the current I increases in a stepped manner from the start time ts, and the current I increases from 0 A to a predetermined value that can be used during normal operation (for example, 150 A). In the actual battery unit 31, when a predetermined time (for example, about several tens of seconds to several minutes) elapses from the start time ts, the current I is limited by the HCU 35 and decreases. On the other hand, FIG. 5 and FIG. 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 lag 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 current I increases, the increasing rates of the output signals Y1 (t) to Y4 (t) are different from each other according to the time constants T1 to T4. For example, since the time constant T1 of the first primary delay calculator 42 is smaller than the other time constants T2 to T4, the output signal Y1 (t) in the transient state is the other output signals Y2 (t) to Y4. Increases early compared to (t). Conversely, since the time constant T4 of the fourth first-order lag calculator 45 is larger than the other time constants T1 to T3, the increase in the output signal Y4 (t) increases with the other output signals Y1 (t) to Y3. Delayed 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 calculation unit 46F calculates the current limit value Ilim for the transient state current I based on the ratio R1 selected by the maximum value selector 46E.

  On the other hand, as shown in FIG. 5, in the steady state where the current I has converged around a predetermined value, the output signals Y1 (t) of the first-order lag calculators 42-45 when the coefficients K1-K4 have the same value. .About.Y4 (t) converge to the same value. At this time, the dividers 46A to 46D output the signal Y1 (t so that the steady value of the primary delay calculator 42 having a small time constant T1 is smaller than the steady values of the other primary delay calculators 43 to 45. ) To Y4 (t) adjusted ratios R1 to R4 are output. For this reason, as shown in FIG. 6, in the steady state where a sufficient time has elapsed from the increase in the current I, the time constant T3 is larger than the time constants T1 and T2, so the output signal Y3 ( The ratio R3 adjusted for t) is larger than the ratios R1 and R2. Similarly, when the current I is further continued, the ratio R4 finally exceeds the ratio R3. As a result, the current limit value calculating unit 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, the current limit is based on the different output signals Y1 (t) to Y4 (t) when the current I changes abruptly in a short time and when the current I changes slowly in a long time. 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 reversible internal resistance, irreversible internal resistance, temperature, etc. 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 time delay calculators 42 to 45 that have different time constants T 1 to T 4 and perform a first order delay calculation based on the charge / discharge current of the power storage device 32. The current control calculator 46 controls the current I of the power storage device 32 based on the calculation results of the four first-order lag 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, 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 target (battery or battery current) is controlled by a plurality of indices (limit conditions) such as reversible internal resistance, irreversible internal resistance, temperature, etc. of the power storage device 32, which are calculated from the current I. Can do. As a result, it is possible to control the current I of the power storage device 32 according to a plurality of limiting conditions while suppressing the operation stop of the power storage device 32. 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, in the four dividers 46A to 46D, the steady-state value of the first-order lag calculator having a small time constant among the four first-order lag calculators 42 to 45 becomes the steady value of the first-order lag calculator having a large time constant. The output signals Y1 (t) to Y4 (t) of the respective first-order lag calculators 42 to 45 are adjusted so as to be smaller.

  For this reason, 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, and therefore the output signal Y4 (t of the first-order lag calculator 45 having a large time constant T4. ) Based on R) becomes 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). The ratio R1 based on 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) obtained by adjusting the output signals Y1 (t) to Y4 (t) by the four dividers 46A to 46D. . Thus, 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 gently, and the current I needs to be limited. Can be extracted.

  Furthermore, current limit value calculation unit 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 according to the rate of change in current, the passage of time, and the like.

  As a result, when the current I changes steeply in a short time, the current control calculator 46 has a ratio R1 of the calculation result (output signal Y1 (t)) of the first-order lag calculator 42 having a small time constant T1, for example. When the upper limit value is approached, 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 has an upper limit on the ratio R4 of the calculation result (output signal Y4 (t)) of the primary delay calculator 45 having a large time constant T4, for example. When the value approaches, the current I of the power storage device 32 can be limited.

  In the above embodiment, the current control calculator 46 includes four dividers 46A to 46D, a maximum value selector 46E, and a 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. Also good.

  In the embodiment, the dividers 46A to 46D are used as the calculation result adjusters. The present invention is not limited to this, and the primary values of the primary delay arithmetic units having a small time constant among a plurality of primary delay arithmetic units are smaller than the steady values of the primary delay arithmetic units having a large time constant. What is necessary is just to adjust the calculation result of a delay calculator, for example, the multiplier which multiplies a coefficient may be sufficient.

  In the above embodiment, the HCU 35 includes the four first-order lag calculators 42 to 45. However, the HCU 35 may include two or three first-order lag calculators, and may include five or more first-order lag calculators. It is good also as a structure provided with a vessel.

  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 a square calculator 41, first to fourth first-order lag calculators 42 to 45, and a current control calculator 46. Of these, the preceding stage (for example, the square calculator 41). ) May be provided in the BC 34, and the HCU 35 may be provided with subsequent portions (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 constitute a single controller.

  In the above embodiment, the maximum output of the engine 21 is made 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 and the like. For this reason, 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 or a nickel metal hydride battery) that can supply necessary power. Alternatively, 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 hybrid hydraulic excavator 1 is 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, and a lift truck. Applicable. The present invention is also applicable to an electric construction machine that omits the engine and drives the hydraulic pump only by the electric motor.

1 Hybrid hydraulic excavator (construction machine)
11 Working device 11D Boom cylinder (hydraulic device)
11E Arm cylinder (hydraulic device)
11F Bucket cylinder (hydraulic device)
21 Engine 23 Hydraulic pump 25 Travel hydraulic motor (hydraulic device)
26 Swing hydraulic motor (hydraulic device)
27 Generator motor (motor)
32 Power storage device 33 Current sensor 34 Battery controller 35 Hybrid controller (controller)
42 to 45 First-order lag calculator 46 Current control calculator 46A to 46D Divider (calculation result adjuster)
46E Maximum value selector 46F Current limit value calculator

Claims (3)

An 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;
In a construction machine having a controller for controlling the output of the power storage device,
The controller is
A plurality of first-order lag calculators having different time constants and performing a first-order lag calculation based on the current of the power storage device;
A construction machine comprising: a current control calculator that controls a current of the power storage device based on a calculation result of the plurality of first-order lag calculators. The current control arithmetic unit is configured so that the steady-state value of the primary delay arithmetic unit having a small time constant among the plurality of primary delay arithmetic units is smaller than the steady-state value of the primary delay arithmetic unit having a large time constant. A plurality of calculation result adjusters for adjusting the calculation results of the first-order lag calculator;
A maximum value selector for selecting the maximum of the adjustment results by the plurality of operation result adjusters;
The construction machine according to claim 1, further comprising: a current limit value calculation unit configured to calculate a current limit value of the power storage device based on an output result from the maximum value selector. 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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