Work vehicles

Abstract

To provide a work vehicle which can avoid the occurrence of system trip in an electrically driven type travel drive system by keeping the change width of the power consumption of an electric motor small even if the rotational speed of the electric motor suddenly changes.SOLUTION: In a wheel loader 1 on which an electrically driven type travel drive system is mounted, a controller 5 calculates the power consumption consumed by an electric motor 34 in the output possible power of an engine 31 on the basis of the stepping amount of an accelerator pedal 121 and an operation amount of an operation lever 122, and outputs the calculated power consumption or a torque calculated based on the power consumption to an inverter 4 for electric motor as a command signal, the inverter 4 for electric motor calculates a command current value related to a correction torque Trc of the electric motor 34 on the basis of the command signal output from the controller 5 and a correction rotational speed Fc of the electric motor 34, and outputs the current having the calculated command current value to the electric motor 34.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a work vehicle equipped with an electrically driven traveling drive system. [Background technology]

[0002] In recent years, work vehicles that employ electric drive systems have appeared with the aim of reducing fuel consumption. Generally, an electric drive system includes an engine, a generator driven by the engine, an electric motor that converts the electric power generated by the generator into rotational force, an inverter that controls the torque generated by the electric motor, and a controller that controls the inverter.

[0003] For example, a wheel loader, which is one type of work vehicle, uses a work device attached to the front of the vehicle body to perform excavation work, excavating natural ground containing earth and crushed stone. During this excavation work, the wheels and electric motor suddenly decelerate when the wheel loader penetrates the bucket into the natural ground to be excavated. Furthermore, the wheels are prone to slip when the wheel loader pushes the bucket into the natural ground. When the wheels slip, the rotation speed of the electric motor suddenly increases. When the rotation speed of the electric motor suddenly decreases or increases, the power consumption of the electric motor suddenly changes, causing the bus voltage to become low or high, which can cause a system trip in the travel drive system.

[0004] A sudden change in the power consumption of an electric motor occurs when the electric motor tries to continue outputting a constant torque when its rotational speed changes suddenly. Therefore, for example, the wheel loader disclosed in Patent Document 1 detects a drop in bus voltage and controls the electric motor so that the output torque of the electric motor decreases in response to the detected drop in bus voltage, thereby suppressing a sudden increase in the power consumption of the electric motor and avoiding a system trip in the traveling drive system. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-26175 Summary of the Invention [Problem to be solved by the invention]

[0006] In the wheel loader described in Patent Document 1, for example, when the vehicle body slips, in order to prevent a sudden increase in the power consumption of the electric motor, the torque command output from the controller to the inverter is controlled so that the output torque of the electric motor is reduced. Then, if the vehicle body grips after the output torque of the electric motor has decreased and the rotational speed of the electric motor has decreased, the controller restores the output torque of the electric motor. In this series of steps, if the update cycle of the controller is slower than the update cycle of the inverter, or if there is a communication delay between the controller and the inverter, the range of change in the output torque of the electric motor will be large. Furthermore, in this situation, if the vehicle body repeatedly slips and grips, i.e., if sudden changes in the output torque of the electric motor are repeated, drivability will deteriorate.

[0007] Therefore, an object of the present invention is to provide a work vehicle that can keep the range of change in the power consumption of the electric motor small even if the rotational speed of the electric motor changes suddenly, thereby avoiding the occurrence of a system trip in the electrically driven traveling drive system. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a work vehicle including a body provided with a plurality of wheels, a working device attached to a frame constituting the body, an engine mounted on the body, an operating device for operating the working device, a hydraulic cylinder that drives the working device based on the amount of operation of the operating device, a hydraulic pump that is driven by the engine and supplies hydraulic oil to the hydraulic cylinder, an accelerator pedal for controlling the driving force of the body, a generator driven by the engine, an electric motor that converts electric power generated by the generator into rotational force and transmits it to the plurality of wheels, an electric motor inverter that calculates torque generated by the electric motor and controls current, a controller that outputs a command signal related to power consumption to be consumed by the electric motor to the electric motor inverter, a depression amount detection device that detects the amount of depression of the accelerator pedal, a rotational speed detection device that detects the rotational speed of the electric motor, and an operation amount detection device that detects the amount of operation of the operating device, wherein the controller acquiring the rotational speed of the electric motor detected by the rotational speed detection device as a reference rotational speed at each update period of the controller; calculating the consumed power to be consumed by the electric motor out of the available output power of the engine based on the depression amount of the accelerator pedal detected by the depression amount detection device and the operation amount of the operation device detected by the operation amount detection device; a reference torque command signal relating to a reference torque of the electric motor based on the calculated consumed power and the reference rotation speed acquired at an update period of the controller is generated as the command signal, and the generated reference torque command signal and the reference rotation speed acquired at an update period of the controller are compared; to the electric motor inverter, and the electric motor inverter The latest rotational speed of the electric motor detected by the rotational speed detection device is acquired as an actual rotational speed that matches the actual rotational speed of the electric motor, and the consumed power to be consumed by the electric motor is calculated based on the reference torque command signal and the reference rotational speed output from the controller, and the calculated consumed power is calculated. and, The acquired actual rotation speed and a command current value relating to the torque generated by the electric motor is calculated based on the command current value calculated by the command current value calculation unit, and a current having the command current value is output to the electric motor. [Effects of the Invention]

[0009] According to the present invention, even if the rotation speed of the electric motor changes suddenly, the change in the power consumption of the electric motor can be kept small, thereby preventing the occurrence of a system trip in an electric drive system. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an external side view showing an example of the configuration of a wheel loader according to each embodiment of the present invention. [Figure 2] 1 is a system configuration diagram showing an example of the configuration of a drive system of a wheel loader. [Figure 3] FIG. 10 is a diagram showing the state of the wheel loader during excavation work. [Figure 4] 2 is a functional block diagram showing the functions of a controller and an electric motor inverter according to the first embodiment of the present invention. FIG. [Figure 5] 4 is a flowchart showing the flow of processing executed by a controller according to the first embodiment. [Figure 6] 3 is a flowchart showing the flow of processing executed by the electric motor inverter according to the first embodiment. [Figure 7] 6 is a graph showing, in time series, the exchange of command signals between a controller and an inverter for an electric motor when the electric motor suddenly decelerates. [Figure 8] 6 is a graph showing, in time series, the exchange of command signals between a controller and an inverter for an electric motor when the electric motor suddenly accelerates. [Figure 9] FIG. 6 is a functional block diagram showing the functions of a controller and an electric motor inverter according to a second embodiment of the present invention. [Figure 10] 10 is a flowchart showing the flow of processing executed by a controller according to the second embodiment. [Figure 11] 10 is a flowchart showing the flow of processing executed by an electric motor inverter according to a second embodiment. [Figure 12] FIG. 10 is a functional block diagram showing the functions of a controller and an electric motor inverter according to a third embodiment of the present invention. [Figure 13] 10 is a flowchart showing the flow of processing executed by an electric motor inverter according to a third embodiment. [Figure 14]FIG. 10 is a functional block diagram showing the functions of a controller and an electric motor inverter according to a fourth embodiment of the present invention. [Figure 15] 10 is a flowchart showing the flow of processing executed by an electric motor inverter according to a fourth embodiment. [Figure 16] FIG. 10 is a functional block diagram showing the functions of a controller and an electric motor inverter according to a fifth embodiment of the present invention. [Figure 17] 10 is a flowchart showing the flow of processing executed by a controller according to the fifth embodiment. [Figure 18] FIG. 10 is a functional block diagram showing the functions of a controller and an electric motor inverter according to a sixth embodiment of the present invention. [Figure 19] 10 is a flowchart showing the flow of processing executed by an electric motor inverter according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Below, as one aspect of the work vehicle according to each embodiment of the present invention, a wheel loader that performs loading and unloading work such as digging up work objects such as earth and sand or minerals and loading them onto a loading destination such as a dump truck will be described.

[0012] <Overall configuration of wheel loader 1> First, the overall configuration of the wheel loader 1 will be described with reference to FIG.

[0013] FIG. 1 is an external side view showing an example of the configuration of a wheel loader 1 according to each embodiment of the present invention.

[0014] The wheel loader 1 is an articulated work vehicle that is steered by bending the vehicle body near the center. Specifically, a front frame 1A, which forms the front part of the vehicle body, and a rear frame 1B, which forms the rear part of the vehicle body, are connected by a center joint 10 so as to be freely rotatable in the left-right direction, and the front frame 1A bends in the left-right direction relative to the rear frame 1B.

[0015] The vehicle body is provided with four wheels 11, two of which are front wheels 11A, one on each side of the front frame 1A, and the other two are rear wheels 11B, one on each side of the rear frame 1B. Of the pair of left and right front and rear wheels 11A and 11B, only the left front and rear wheels 11A and 11B are shown in Fig. 1. There is no particular restriction on the specific number of wheels 11 provided on the vehicle body.

[0016] A hydraulically driven working device 2 used for cargo handling work is attached to the front of the front frame 1A. The working device 2 has a lift arm 21 whose base end is attached to the front frame 1A, two lift arm cylinders 22 that drive the lift arm 21, a bucket 23 attached to the tip of the lift arm 21, a bucket cylinder 24 that drives the bucket 23, and a bell crank 25 that is rotatably connected to the lift arm 21 and forms a link mechanism between the bucket 23 and the bucket cylinder 24.

[0017] The two lift arm cylinders 22 and the bucket cylinder 24 are both embodiments of hydraulic cylinders that drive the working device 2. The two lift arm cylinders 22 are arranged side by side in the left-right direction of the vehicle body, but in FIG. 1, only the lift arm cylinder 22 arranged on the left side is shown by a dashed line.

[0018] The lift arm 21 rotates up and down relative to the front frame 1A when hydraulic oil is supplied to the two lift arm cylinders 22, causing the rods 220 to extend and retract. More specifically, the lift arm 21 rotates upward relative to the front frame 1A when the rods 220 of the two lift arm cylinders 22 extend, and rotates downward relative to the front frame 1A when the rods 220 retract.

[0019] The bucket 23 rotates vertically relative to the lift arm 21 when hydraulic oil is supplied to the bucket cylinder 24 and the rod 240 extends or contracts. More specifically, the bucket 23 tilts (rotates upward relative to the lift arm 21) when the rod 240 of the bucket cylinder 24 extends, and dumps (rotates downward relative to the lift arm 21) when the rod 240 contracts.

[0020] The bucket 23 can be replaced with various attachments such as a blade, and the wheel loader 1 can perform various tasks such as earth-dozing and snow removal in addition to excavation work using the bucket 23.

[0021] The rear frame 1B is provided with a cab 12 in which an operator sits, a machine room 13 that houses various devices required to drive the wheel loader 1, and a counterweight 14 that maintains balance with the work implement 2 so that the vehicle body does not tilt. On the rear frame 1B, the cab 12 is located at the front, the counterweight 14 at the rear, and the machine room 13 between the cab 12 and the counterweight 14.

[0022] <Wheel loader 1 drive system> Next, the drive system of the wheel loader 1 will be described with reference to FIG.

[0023] FIG. 2 is a system configuration diagram showing an example of the configuration of a drive system of the wheel loader 1. As shown in FIG.

[0024] In the wheel loader 1, the traveling of the vehicle body is controlled by an electric drive system, and the operation of the work implement 2 and steering is controlled by a hydraulic drive system. The engine 31, which is the drive source for the electric drive system and the hydraulic drive system, is configured to include an internal combustion engine such as a diesel engine, and the rotational speed (rotational speed) is controlled so as to ensure the power consumed by the electric drive system and the hydraulic drive system.

[0025] The electric drive system includes a generator 32 driven by an engine 31, a generator inverter 33 that controls the torque generated by the generator 32, an electric motor 34 that converts the power generated by the generator 32 into rotational force, an electric motor inverter 4 that controls the torque generated by the electric motor 34, and a transmission 35 connected to the output side of the electric motor 34.

[0026] The generator 32 is connected to the engine 31 via a gear 31A, and is also connected to the electric motor 34 via a generator inverter 33 and an electric motor inverter 4. The generator 32 generates electricity based on the output torque of the engine 31 and supplies the generated electricity to the electric motor 34.

[0027] The generator inverter 33 is electrically connected to the controller 5, and outputs a current related to the torque generated by the generator 32 to the generator 32 based on a command signal output from the controller 5.

[0028] The electric motor 34 converts the electric power supplied from the generator 32 into rotational force, and transmits the converted rotational force (torque) to the transmission 35. The rotational speed of the electric motor 34 is detected by a rotational speed sensor 34A, which serves as a rotational speed detection device attached to the electric motor 34.

[0029] The electric motor inverter 4, like the generator inverter 33, is electrically connected to the controller 5, and outputs a command current related to the torque generated by the electric motor 34 to the electric motor 34 based on a command signal output from the controller 5.

[0030] The command signal output by the controller 5 is calculated based on the depression amount of an accelerator pedal 121, which is provided in the driver's cab 12 (see FIG. 1) and controls the driving force of the vehicle body. The depression amount of the accelerator pedal 121 is detected by a depression amount sensor 121A, which serves as a depression amount detection device attached to the accelerator pedal 121.

[0031] The transmission 35 switches the gear ratio between the input shaft and the output shaft by switching multiple engagement clutches provided inside. As a result, the torque transmitted from the electric motor 34 to the transmission 35 (torque generated by the electric motor 34) is multiplied by the gear ratio and then output from the output shaft of the transmission 35. The torque output from the transmission 35 is then transmitted to the four wheels 11 via the propeller shaft and front and rear differential mechanisms, which rotate the four wheels 11 and cause the wheel loader 1 to travel.

[0032] The hydraulic drive system includes a hydraulic pump 61 driven by the engine 31 to discharge hydraulic oil, a pair of left and right steering cylinders 10L, 10R, two lift arm cylinders 22, a bucket cylinder 24, and a directional control valve device 62 that controls the flow (direction and flow rate) of hydraulic oil discharged from the hydraulic pump 61 and supplied to each of the hydraulic cylinders 10L, 10R, 22, 24.

[0033] The hydraulic pump 61 is connected to the engine 31 via the gear 31A, similar to the generator 32. That is, the generator 32 and the hydraulic pump 61 are connected in parallel to the engine 31 and the gear 31A, and the output power of the engine 31 is distributed to the generator 32 (electric drive system side) and the hydraulic pump 61 (hydraulic drive system side).

[0034] The directional control valve device 62 is provided between the hydraulic pump 61 and each of the hydraulic cylinders 10L, 10R, 22, 24, and is controlled based on a command signal output from the controller 5. An operation lever 122 as an operation device for operating the working implement 2 (lift arm 21 and bucket 23) and a handle 123 as a steering device for the vehicle body are provided inside the operator's cab 12 (see FIG. 1 ), and operation signals corresponding to the operation amounts of the operation lever 122 and the handle 123 are input to the controller 5. The controller 5 then outputs command signals to the directional control valve device 62 based on the operation signal output from the operation lever 122 and the operation signal output from the handle 123, respectively.

[0035] The amount of operation of the operating lever 122 is detected, for example, by an operating amount sensor 122A attached to the operating lever 122. In addition to the operating amount sensor 122A, the operating amount detection device for detecting the amount of operation of the operating lever 122 may also be one that estimates the amount of operation by detecting the discharge pressure of the hydraulic pump 61, the angular velocity of the working device 2, or the length and pressure of each of the hydraulic cylinders 22, 24. The amount of operation of the handle 123 is detected by an angle sensor (not shown) attached to the handle 123, etc.

[0036] In this way, both the electric drive system and the hydraulic drive system are controlled based on command signals from the controller 5. The controller 5 receives inputs such as the rotation speed of the electric motor 34 detected by the rotation speed sensor 34A, the depression amount of the accelerator pedal 121 detected by the depression amount sensor 121A, and operation signals from the operation lever 122 and the steering wheel 123, and outputs command signals to the directional control valve device 62, the generator inverter 33, the electric motor inverter 4, etc. based on the input data and signals.

[0037] <Wheel loader 1 excavation work> Next, the excavation work of the wheel loader 1 will be described with reference to FIG.

[0038] FIG. 3 is a diagram showing the wheel loader 1 during excavation work.

[0039] The wheel loader 1 first moves forward toward the natural ground X, which is the excavation target, and plunges the bucket 23 into the natural ground X. At this time, depending on the type of minerals that make up the natural ground X and the condition (hardness) of the natural ground X, the wheel loader 1 may require a large tractive force, causing the vehicle body to stall.

[0040] Next, the wheel loader 1 tilts the bucket 23 while pushing it into the natural ground X to scoop up the load, such as earth and sand, minerals, etc. At this time, depending on the condition of the ground, the wheels 11 may slip, causing the vehicle body to slip.

[0041] When the vehicle body stalls, the rotation speed of the electric motor 34 suddenly decelerates, and conversely, when the vehicle body slips, the rotation speed of the electric motor 34 suddenly increases. When the rotation speed of the electric motor suddenly decreases or increases in this way, the power consumption of the electric motor 34 suddenly changes, causing the bus voltage to become low or high, which may cause the electric drive system to trip. Therefore, in the wheel loader 1, the controller 5 and the electric motor inverter 4 perform control so that the electric drive system does not trip. Below, the specific functional configurations of the controller 5 and the electric motor inverter 4 will be described for each embodiment.

[0042] First Embodiment First, the controller 5 and the electric motor inverter 4 according to the first embodiment of the present invention will be described with reference to FIGS.

[0043] FIG. 4 is a functional block diagram showing the functions of the controller 5 and the electric motor inverter 4 according to the first embodiment.

[0044] The controller 5 is configured by connecting a CPU, RAM, ROM, HDD, input I / F, and output I / F via a bus. Various sensors such as the depression amount sensor 121A, operation amount sensor 122A, and rotation speed sensor 34A are connected to the input I / F, and the electric motor inverter 4 is connected to the output I / F.

[0045] Similarly, the electric motor inverter 4 is configured by interconnecting a CPU, RAM, ROM, HDD, input I / F, and output I / F via a bus. Various sensors such as the rotation speed sensor 34A are connected to the input I / F, and the electric motor 34 and the like are connected to the output I / F.

[0046] In such a hardware configuration, the CPU reads out a control program (software) stored on a recording medium such as a ROM, HDD, or optical disk, expands it on RAM, and executes the expanded control program, whereby the control program and the hardware work together to realize the functions of the controller 5 and the inverter 4 for the electric motor.

[0047] In this embodiment, the controller 5 and the electric motor inverter 4 are each described as a computer configured by a combination of software and hardware, but this is not limiting, and for example, as an example of another computer configuration, an integrated circuit that realizes the functions of a control program executed on the wheel loader 1 side may also be used.

[0048] The controller 5 includes a data acquisition unit 51 , an engine power distribution unit 52 , and a reference torque command unit 53 .

[0049] The data acquisition unit 51 acquires data relating to the depression amount of the accelerator pedal 121 detected by the depression amount sensor 121A, the operation amount of the operating lever 122 detected by the operation amount sensor 122A, and the rotation speed of the electric motor 34 detected by the rotation speed sensor 34A.

[0050] The rotation speed of the electric motor 34 is also acquired by a data acquisition unit 41 of the electric motor inverter 4, which will be described later. However, because the update cycle of the electric motor inverter 4 is shorter than the update cycle of the controller 5, the rotation speed of the electric motor 34 acquired by the data acquisition unit 51 of the controller 5 is older data than the rotation speed of the electric motor 34 acquired by the data acquisition unit 41 of the electric motor inverter 4. Therefore, the rotation speed of the electric motor 34 acquired by the data acquisition unit 51 of the controller 5 is used as reference rotation speed data of the electric motor 34, and will be referred to as the "reference rotation speed Fs" below.

[0051] The engine power distribution unit 52 calculates the power consumption amount to be consumed by the electric motor 34 out of the available output power of the engine 31, based on the depression amount of the accelerator pedal 121 and the operation amount of the operation lever 122 acquired by the data acquisition unit 51. In other words, the engine power distribution unit 52 calculates the power of the engine 31 to be distributed to the electric drive system side and the hydraulic drive system side, respectively, according to the operating state of the vehicle body.

[0052] The reference torque command unit 53 generates a reference torque command signal related to the reference torque Trs of the electric motor 34 based on the power consumption of the electric motor 34 calculated by the engine power distribution unit 52 and the reference rotation speed Fs acquired by the data acquisition unit 51, and outputs the signal to the electric motor inverter 4. Note that the power consumption of the electric motor 34 is determined by the product of the rotation speed of the electric motor 34 and the torque generated by the electric motor, so the controller 5 can calculate a reference torque (reference torque Trs) based on the power consumption of the electric motor 34 and the reference rotation speed Fs, and generate the reference torque command signal.

[0053] The electric motor inverter 4 includes a data acquisition unit 41 , a power consumption calculation unit 42 , a correction torque command unit 43 , a current command unit 44 , and a storage unit 45 .

[0054] The data acquisition unit 41 acquires data relating to the rotational speed of the electric motor 34 detected by the rotational speed sensor 34A. As described above, the update period of the electric motor inverter 4 is shorter than the update period of the controller 5, and therefore the rotational speed of the electric motor 34 acquired by the data acquisition unit 41 of the electric motor inverter 4 is data that matches the actual rotational speed of the electric motor 34. Therefore, hereinafter, the rotational speed of the electric motor 34 acquired by the data acquisition unit 41 of the electric motor inverter 4 will be referred to as the "actual rotational speed Fr" to distinguish it from the "reference rotational speed Fs."

[0055] The power consumption calculation unit 42 calculates the power consumption to be consumed by the electric motor 34 based on the reference torque command signal output from the reference torque command unit 53 of the controller 5 and the reference rotation speed Fs acquired by the data acquisition unit 51 of the controller 5. The power consumption of the electric motor 34 calculated by the power consumption calculation unit 42 is the same value as the power consumption of the electric motor 34 calculated by the engine power distribution unit 52 of the controller 5.

[0056] Furthermore, when the electric motor inverter 4 acquires a reference torque command signal and a reference rotation speed Fs from the controller 5, the power consumption calculation unit 42 calculates the power consumption of the electric motor 34 based on the acquired signals and data, and when the electric motor inverter 4 does not acquire a reference torque command signal and a reference rotation speed Fs from the controller 5, the power consumption calculation unit 42 calculates the power consumption of the electric motor 34 based on the previous reference torque command signal and reference rotation speed Fs stored in the memory unit 45.

[0057] The correction torque command unit 43 calculates the torque generated by the electric motor 34 based on the power consumption of the electric motor 34 calculated by the power consumption calculation unit 42 and the actual rotation speed Fr acquired by the data acquisition unit 41. The torque of the electric motor 34 calculated by this correction torque command unit 43 is a torque (hereinafter referred to as "correction torque Trc") obtained by correcting the reference torque calculated by the controller 5 based on the actual rotation speed Fr. Therefore, the actual rotation speed Fr acquired by the electric motor inverter 4 corresponds to the "correction rotation speed Fc" used to calculate the correction torque Trc, which is a correction value of the reference torque Trs calculated by the controller 5 (Fr = Fc). The correction torque command unit 43 outputs a correction torque command signal related to the calculated correction torque Trc to the current command unit 44.

[0058] The current command unit 44 calculates a command current value corresponding to the correction torque command signal generated by the correction torque command unit 43, and outputs a command current having the calculated command current value to the electric motor 34. In other words, the current command unit 44 converts the correction torque command signal into a command current and outputs it to the electric motor 34.

[0059] Next, a specific flow of processing executed within the controller 5 will be described with reference to FIG.

[0060] FIG. 5 is a flowchart showing the flow of processing executed by the controller 5 according to the first embodiment.

[0061] In the controller 5, first, the data acquisition unit 51 acquires the depression amount of the accelerator pedal 121 output from the depression amount sensor 121A and the operation amount of the operation lever 122 detected by the operation amount sensor 122A (step S501).

[0062] Next, the engine power distribution unit 52 calculates the power consumption of the electric motor 34 based on the depression amount of the accelerator pedal 121 and the operation amount of the operation lever 122 acquired in step S501 (step S502). Next, the data acquisition unit 51 acquires the rotation speed of the electric motor 34 output from the rotation speed sensor 34A as a reference rotation speed Fs (step S503).

[0063] Then, the reference torque command unit 53 outputs a reference torque command signal relating to the reference torque Trs of the electric motor 34 to the electric motor inverter 4 based on the power consumption of the electric motor 34 calculated in step S502 and the reference rotational speed Fs acquired in step S503 (step S504).

[0064] Furthermore, the controller 5 executes the process of step S504 and outputs the reference rotation speed Fs acquired in step S503 to the electric motor inverter 4 (step S505). After completing the processes of step S504 and step S505, the controller 5 returns to the process of step S501 and repeats it.

[0065] Next, a specific flow of processing executed within the electric motor inverter 4 will be described with reference to FIG.

[0066] FIG. 6 is a flowchart showing the flow of processing executed by the electric motor inverter 4 according to the first embodiment.

[0067] First, when the electric motor inverter 4 acquires the reference torque command signal output in step S504 and the reference rotation speed Fs output in step S505 in the controller 5 (step S401 / YES), it updates the reference torque command signal and the reference rotation speed Fs as current values ​​(step S402).

[0068] On the other hand, if the electric motor inverter 4 does not acquire the reference torque command signal and the reference rotation speed Fs from the controller 5 (step S401 / NO), it reads the previously acquired reference torque command signal and the reference rotation speed Fs from the memory unit 45 (step S403).

[0069] Next, the power consumption calculation unit 42 calculates the power consumption of the electric motor 34 based on the reference torque command signal and the reference rotational speed Fs updated in step S402 or read in step S403 (step S404).

[0070] Next, the data acquiring unit 41 acquires the rotational speed of the electric motor 34 output from the rotational speed sensor 34A as the actual rotational speed Fr (corresponding to the corrected rotational speed Fc) (step S405). Then, the corrected torque command unit 43 calculates the corrected torque Trc based on the power consumption of the electric motor 34 calculated in step S404 and the actual rotational speed Fr acquired in step S405 (step S406), and outputs a corrected torque command signal related to the corrected torque Trc to the current command unit 44 (step S407).

[0071] The current command unit 44 converts the correction torque command signal output in step S407 into a corresponding command current and outputs it to the electric motor 34 (step S408). After completing the process of step S408, the electric motor inverter 4 returns to the process of step S401 and repeats it.

[0072] Next, the actions and effects achieved by the processing in the controller 5 and the processing in the electric motor inverter 4 will be described with reference to FIGS.

[0073] Fig. 7 is a graph showing, in time series, the exchange of command signals between the controller 5 and the electric motor inverter 4 when the electric motor 34 suddenly decelerates. Fig. 8 is a graph showing, in time series, the exchange of command signals between the controller 5 and the electric motor inverter 4 when the electric motor 34 suddenly accelerates.

[0074] 7 and 8, the length of the update cycle of the electric motor inverter 4 and the length of the communication delay between the controller 5 and the electric motor inverter 4 are assumed to be sufficiently shorter than the update cycle of the controller 5.

[0075] When the electric motor 34 suddenly decelerates, as shown in FIG. 7, the controller 5 and the electric motor inverter 4 issue a command to the electric motor 34 so that the torque generated by the electric motor 34 increases in accordance with the rotation speed.

[0076] First, at time t01, the controller 5 acquires the rotational speed of the electric motor 34 from the rotational speed sensor 34A (O1), and generates a reference torque command signal using the rotational speed value as a reference rotational speed Fs (shown in the step graph indicated by the solid line at the top of FIG. 7). Next, the generated reference torque command signal is output from the controller 5 at time t02 (O2).

[0077] Then, after a communication delay between the controller 5 and the electric motor inverter 4, the reference torque command signal output from the controller 5 at time t03 reaches the electric motor inverter 4 (R3). Therefore, the reference torque Trs output from the controller 5 and acquired by the electric motor inverter 4 rises in a step-like manner as shown by the graph q01 indicated by the solid line at the bottom of FIG.

[0078] On the other hand, since the electric motor inverter 4 has a short update cycle as described above, it can generate a torque command signal (corrected torque command signal) in accordance with the actual rotation speed of the electric motor 34, and the corrected torque Trc calculated within the electric motor inverter 4 increases linearly as shown by the dashed dotted line in graph q02 at the bottom of FIG. 7.

[0079] In this embodiment, the electric motor inverter 4 outputs to the electric motor 34 a command current related to a corrected torque obtained by correcting the reference torque command signal output from the controller 5 based on the actual rotation speed Fr (the linear graph shown by the dashed line at the top of FIG. 7). Therefore, as shown in graph q02 in FIG. 7, the torque of the electric motor 34 can be changed smoothly, and the electric motor 34 can output the maximum torque that it can output.

[0080] Next, when the speed of the electric motor 34 increases suddenly, as shown in FIG. 8, the controller 5 and the electric motor inverter 4 issue a command to the electric motor 34 so that the torque generated by the electric motor 34 decreases in accordance with the rotation speed.

[0081] As in the case where the electric motor 34 suddenly decelerates, the controller 5 first acquires the rotational speed of the electric motor 34 from the rotational speed sensor 34A at time t11 (O1), and generates a reference torque command signal using the value of the rotational speed as a reference rotational speed Fs (shown by the solid line in the step graph at the top of FIG. 8). Next, the generated reference torque command signal is output from the controller 5 at time t12 (O2).

[0082] Then, after a communication delay between the controller 5 and the electric motor inverter 4, the reference torque command signal output from the controller 5 at time t13 reaches the electric motor inverter 4 (R3). Therefore, the reference torque Trs output from the controller 5 and acquired by the electric motor inverter 4 drops in a step-like manner as shown by graph q11, which is indicated by a solid line at the bottom of FIG.

[0083] On the other hand, the electric motor inverter 4 can generate a torque command signal (corrected torque command signal) in accordance with the actual rotation speed of the electric motor 34, and therefore the corrected torque Trc calculated within the electric motor inverter 4 decreases linearly as shown by the dashed dotted line in graph q12 at the bottom of FIG. 8.

[0084] Therefore, even if the speed of the electric motor 34 suddenly increases, the electric motor inverter 4 outputs to the electric motor 34 a command current corresponding to a corrected torque obtained by correcting the reference torque command signal output from the controller 5 based on the actual rotational speed Fr (the linear graph shown by the dashed line at the top of FIG. 8). This makes it possible to smoothly change the torque of the electric motor 34 as shown in graph q12 in FIG. 8, and also enables the electric motor 34 to output the maximum torque that it can output.

[0085] As described above, the electric motor inverter 4 smoothly changes the torque command for the electric motor 34 in response to a sudden increase or decrease in the rotational speed, so that even if the rotational speed of the electric motor changes suddenly, the range of change in the power consumption of the electric motor is kept small, and it is possible to avoid the occurrence of a system trip in the electric drive system (travel drive system).

[0086] Second Embodiment Next, a controller 5A and an electric motor inverter 4A according to a second embodiment of the present invention will be described with reference to Figures 9 to 11. In Figures 9 to 11, components that are common to those described for the configuration of the controller 5 and the electric motor inverter 4 according to the first embodiment are given the same reference numerals, and their description will be omitted. The same applies to third to sixth embodiments described below.

[0087] Fig. 9 is a functional block diagram showing the functions of the controller 5A and the electric motor inverter 4A according to the second embodiment. Fig. 10 is a flowchart showing the flow of processing executed by the controller 5A according to the second embodiment. Fig. 11 is a flowchart showing the flow of processing executed by the electric motor inverter 4A according to the second embodiment.

[0088] 9, a controller 5A according to this embodiment includes a data acquisition unit 51A and an engine power distribution unit 52A. That is, unlike the controller 5 according to the first embodiment, the controller 5A does not include a "reference torque command unit."

[0089] The data acquiring unit 51A acquires data relating to the depression amount of the accelerator pedal 121 detected by the depression amount sensor 121A and the operation amount of the operating lever 122 detected by the operation amount sensor 122A. That is, in this embodiment, unlike the data acquiring unit 51 in the first embodiment, the data acquiring unit 51A does not acquire the rotation speed of the electric motor 34 detected by the rotation speed sensor 34A.

[0090] The engine power distribution unit 52A calculates the power consumption to be consumed by the electric motor 34 based on the depression amount of the accelerator pedal 121 and the operation amount of the operation lever 122 acquired by the data acquisition unit 51A. Then, the engine power distribution unit 52A generates a power consumption command signal, which is a command signal based on the calculated power consumption of the electric motor 34, and outputs it to the electric motor inverter 4A. That is, in this embodiment, unlike the controller 5 according to the first embodiment, the controller 5A outputs a power consumption command signal, rather than a reference torque command signal, to the electric motor inverter 4A.

[0091] Moreover, the electric motor inverter 4A according to this embodiment includes a data acquisition unit 41, a correction torque command unit 43A, a current command unit 44, and a storage unit 45A. That is, unlike the electric motor inverter 4 according to the first embodiment, the electric motor inverter 4A does not include a "power consumption calculation unit."

[0092] The data acquiring unit 41, like the data acquiring unit 41 in the first embodiment, acquires data relating to the rotation speed of the electric motor 34 detected by the rotation speed sensor 34A as the actual rotation speed Fr.

[0093] The correction torque command unit 43A calculates a correction torque Trc of the electric motor 34 based on the power consumption command signal output from the engine power distribution unit 52A of the controller 5A and the actual rotation speed Fr acquired by the data acquisition unit 41A. Then, the correction torque command unit 43A outputs a correction torque command signal related to the calculated correction torque Trc to the current command unit 44.

[0094] When the electric motor inverter 4A receives a power consumption command signal from the controller 5A, the correction torque command unit 43A calculates the correction torque Trc based on the received signal, and when the electric motor inverter 4A does not receive a power consumption command signal from the controller 5A, the correction torque command unit 43A calculates the correction torque Trc based on the previous power consumption command signal stored in the memory unit 45A.

[0095] The current command unit 44 converts the correction torque command signal output from the correction torque command unit 43A into a command current and outputs it to the electric motor 34, similar to the current command unit 44 in the first embodiment.

[0096] As shown in FIG. 10, in the controller 5A, first, the data acquisition unit 51A acquires the depression amount of the accelerator pedal 121 detected by the depression amount sensor 121A and the operation amount of the operation lever 122 detected by the operation amount sensor 122A (step S501).

[0097] Next, the engine power distribution unit 52A calculates the power consumption of the electric motor 34 based on the depression amount of the accelerator pedal 121 and the operation amount of the operation lever 122 acquired in step S501 (step S502). Subsequently, the engine power distribution unit 52A generates a power consumption command signal based on the power consumption of the electric motor 34 calculated in step S502, and outputs the signal to the electric motor inverter 4A (step S506). After completing the processing of step S506, the controller 5A returns to the processing of step S501 and repeats the processing.

[0098] Then, as shown in FIG. 11, in the electric motor inverter 4A, first, when the consumed power command signal output in step S506 in the controller 5A is acquired (step S401A / YES), the consumed power command signal is updated (step S402A).

[0099] On the other hand, when the electric motor inverter 4A does not acquire a consumption power command signal from the controller 5A (step S401A / NO), it reads the previously acquired consumption power command signal from the storage unit 45A (step S403A).

[0100] Next, the data acquiring unit 41 acquires the rotation speed of the electric motor 34 output from the rotation speed sensor 34A as the actual rotation speed Fr (corresponding to the corrected rotation speed Fc) (step S405).

[0101] Next, the correction torque command unit 43A calculates a correction torque Trc of the electric motor 34 based on the consumed power command signal updated in step S402A or read in step S403A and the actual rotation speed Fr acquired in step S405 (step S406A).The correction torque command unit 43A then outputs a correction torque command signal related to the correction torque Trc calculated in step S406A to the current command unit 44 (step S407).

[0102] The current command unit 44 converts the corrected torque command signal output in step S407 into a corresponding command current and outputs it to the electric motor 34 (step S408). After completing the process of step S408, the electric motor inverter 4A returns to the process of step S401A and repeats it.

[0103] According to the controller 5A of this embodiment, the power consumption of the electric motor 34 is output as a command signal to the electric motor inverter 4A without converting the power consumption of the electric motor 34 into a reference torque Trs, thereby simplifying the processing within the controller 5A and the electric motor inverter 4A and reducing the load on each CPU. Furthermore, this embodiment also provides the same functions and effects as those of the first embodiment.

[0104] Third Embodiment Next, a controller 5 and an electric motor inverter 4B according to a third embodiment of the present invention will be described with reference to FIGS.

[0105] Fig. 12 is a functional block diagram showing the functions of the controller 5 and the electric motor inverter 4B according to the third embodiment. Fig. 13 is a flowchart showing the flow of processing executed by the electric motor inverter 4B according to the third embodiment.

[0106] The controller 5 according to this embodiment has the same functions as the controller 5 according to the first embodiment, so a description of the controller 5 will be omitted and the following description will mainly focus on the electric motor inverter 4B.

[0107] As shown in FIG. 12, the electric motor inverter 4B includes a data acquisition unit 41, a power consumption calculation unit 42, a correction torque command unit 43B, a current command unit 44, a memory unit 45, and in addition, a rotation speed sudden change determination unit 46.

[0108] The electric motor inverter 4B according to this embodiment includes a sudden rotation speed change determination unit 46 that determines whether or not the rotation speed of the electric motor 34 has suddenly changed, based on the rotation speed of the electric motor 34 detected by the rotation speed sensor 34A. Specifically, the sudden rotation speed change determination unit 46 calculates the absolute value |Fs-Fr| of the difference between the reference rotation speed Fs output from the controller 5 and the actual rotation speed Fr acquired by the data acquisition unit 41, and compares the calculated absolute value |Fs-Fr| to determine whether it is equal to or greater than a predetermined threshold value Fth.

[0109] Here, the "predetermined threshold value Fth" corresponds to a value obtained by multiplying the maximum acceleration derived based on the maximum torque and moment of inertia of the electric motor 34 by the update period of the controller 5, for example.

[0110] When it is determined in the rotational speed sudden change determination unit 46 that the rotational speed of the electric motor 34 has suddenly changed, that is, the absolute value |Fs - Fr| is equal to or greater than a predetermined threshold value Fth (|Fs - Fr| ≥ Fth), the correction torque command unit 43B calculates a correction torque Trc based on the power consumption of the electric motor 34 calculated by the power consumption calculation unit 42 and the actual rotational speed Fr acquired by the data acquisition unit 41, and outputs a correction torque command signal to the current command unit 44.

[0111] On the other hand, when it is determined in the rotational speed sudden change determination unit 46 that the rotational speed of the electric motor 34 has not suddenly changed, that is, the absolute value |Fs - Fr| is less than a predetermined threshold value Fth (|Fs - Fr| < Fth), the correction torque command unit 43B outputs the reference torque command signal output from the controller 5 to the current command unit 44.

[0112] As shown in FIG. 13, in the electric motor inverter 4B, the processes of step S401, step S402, step S403, step S404, and step S405 are the same as the processes in the electric motor inverter 4 according to the first embodiment.

[0113] After the data acquisition unit 41 acquires the actual rotational speed Fr in step S405, the rotational speed sudden change determination unit 46 determines whether the absolute value |Fs - Fr| of the difference between the reference rotational speed Fs updated in step S402 or read in step S403 and the actual rotational speed Fr acquired in step S405 is equal to or greater than a predetermined threshold value Fth (step S409).

[0114] When it is determined in step S409 that the absolute value |Fs - Fr| is equal to or greater than a predetermined threshold value Fth (|Fs - Fr| ≥ Fth) (step S409 / YES), the correction torque command unit 43B calculates the correction torque Trc of the electric motor 34 based on the power consumption of the electric motor 34 calculated in step S404 and the actual rotational speed Fr acquired in step S405 (step S406).

[0115] Then, like the inverter 4 for an electric motor according to the first embodiment, the inverter 4B for an electric motor proceeds to step S407 and step S408, and the current command unit 44 converts the corrected torque command signal into a corresponding command current and outputs it to the electric motor 34.

[0116] On the other hand, when it is determined in step S409 that the absolute value |Fs - Fr| is less than the predetermined threshold value Fth (|Fs - Fr| < Fth) (step S409 / NO), the corrected torque command unit 43B outputs the reference torque command signal from the controller 5 as it is to the current command unit 44 (step S410).

[0117] Subsequently, the current command unit 44 converts the reference torque command signal into a command current and outputs it to the electric motor 34 (step S411). When the processing of step S408 or the processing of step S411 is completed, the inverter 4B for an electric motor returns to step S401 and repeats the process.

[0118] According to the inverter 4B for an electric motor according to the present embodiment, control based on the corrected torque Trc is performed on the electric motor 34 only when the rotational speed of the electric motor �4 changes suddenly. When the rotational speed of the electric motor 34 does not change suddenly, the process of calculating the corrected torque Trc can be omitted, so the load on the CPU is reduced. Also, in the present embodiment, the same operations and effects as those in the first embodiment are achieved.

[0119] <Fourth Embodiment> Next, the controller 5C and the inverter 4C for an electric motor according to the fourth embodiment of the present invention will be described with reference to FIGS. 14 and 15.

[0120] FIG. 14 is a functional block diagram showing the functions of the controller 5C and the inverter 4C for an electric motor according to the fourth embodiment. FIG. 15 is a flowchart showing the flow of processing executed by the inverter 4C for an electric motor according to the fourth embodiment.

[0121] The controller 5C according to this embodiment includes a data acquisition unit 51, an engine power distribution unit 52, a reference torque command unit 53, and also a sudden change flag acquisition unit 54. This sudden change flag acquisition unit 54 acquires a sudden rotation speed change flag output from a sudden rotation speed change determination unit 46C of the electric motor inverter 4C, which will be described later.

[0122] Furthermore, the electric motor inverter 4C according to this embodiment includes a data acquisition unit 41, a power consumption calculation unit 42, a sudden change in rotation speed determination unit 46C, a correction torque command unit 43B, a current command unit 44, and a memory unit 45, similar to the electric motor inverter 4B according to the third embodiment.

[0123] In the electric motor inverter 4C, unlike the electric motor inverter 4B according to the third embodiment, when the sudden rotation speed change determination unit 46C determines that the rotation speed of the electric motor 34 has suddenly changed, it outputs a flag ON signal to the controller 5C to set the sudden rotation speed change flag to ON (sudden rotation speed change flag = ON), and when it does not determine that the rotation speed of the electric motor 34 has suddenly changed, it outputs a flag OFF signal to the controller 5C to set the sudden rotation speed change flag to OFF (sudden rotation speed change flag = OFF).

[0124] As shown in FIG. 15, in the electric motor inverter 4C, the processes of steps S401, S402, S403, S404, S405, and S409 are similar to those in the electric motor inverter 4B according to the third embodiment.

[0125] If it is determined in step S409 that the absolute value |Fs-Fr| is equal to or greater than the predetermined threshold value Fth (|Fs-Fr|≧Fth) (step S409 / YES), the rotation speed sudden change determination unit 46C outputs a flag ON signal to the controller 5C (step S412). Then, the electric motor inverter 4C proceeds to steps S406, S407, and S408, similar to the processing in the electric motor inverter 4B according to the third embodiment.

[0126] On the other hand, when it is determined in step S409 that the absolute value |Fs - Fr| is less than a predetermined threshold value Fth (|Fs - Fr| < Fth) (step S409 / NO), the rotational speed rapid change determination unit 46C outputs a flag OFF signal to the controller 5C (step S413). Then, the electric motor inverter 4C proceeds to steps S410 and S411 in the same manner as the processing in the electric motor inverter 4B according to the third embodiment.

[0127] According to the controller 5C and the electric motor inverter 4C according to the present embodiment, when the rotational speed of the electric motor 34 rapidly changes, the electric motor inverter 4C outputs an ON signal related to the rotational speed rapid change flag to the controller 5C. Therefore, the controller 5C can execute the processing required along with the rapid change in the rotational speed of the electric motor 34, and can easily grasp the current situation by determining whether the generated reference torque command signal is valid. Also, in the present embodiment, the same operations and effects as those in the first embodiment are exhibited.

[0128] <Fifth Embodiment> Next, the controller 5D and the electric motor inverter 4D according to the fifth embodiment of the present invention will be described with reference to FIGS. 16 and 17.

[0129] FIG. 16 is a functional block diagram showing the functions of the controller 5D and the electric motor inverter 4D according to the fifth embodiment. FIG. 17 is a flowchart showing the flow of processing executed by the controller 5D according to the fifth embodiment.

[0130] The controller 5D according to the present embodiment includes a data acquisition unit 51, an engine power distribution unit 52, in addition to an arrival time estimation unit 55, a rotational speed estimation unit 56, an estimated torque command unit 57, and a storage unit 58.

[0131] The arrival time estimation unit 55 calculates an estimate of the time it takes for the torque command signal output by the controller 5D to reach the electric motor inverter 4D (to be received by the electric motor inverter 4D), i.e., the arrival time of the command signal output by the controller 5D to reach the electric motor inverter 4D, based on the respective update periods of the controller 5D and the electric motor inverter 4D, and the communication delay time between the controller 5D and the electric motor inverter 4D.

[0132] The update cycles of the controller 5D and the electric motor inverter 4D, and the communication delay time between the controller 5D and the electric motor inverter 4D are stored in the storage unit 58.

[0133] The rotational speed estimation unit 56 calculates the rotational acceleration (rate of change / gradient of the rotational speed) of the electric motor 34, based on the reference rotational speed Fs currently acquired by the data acquisition unit 51 (current reference rotational speed Fs1) and the previously acquired reference rotational speed Fs (previous reference rotational speed Fs0) stored in the memory unit 58. Then, based on the calculated rotational acceleration and the torque command signal arrival time estimated by the arrival time estimation unit 55, the rotational speed estimation unit 56 calculates an estimate (estimated rotational speed) of the rotational speed of the electric motor 34 at the time when the torque command signal output by the controller 5D reaches the electric motor inverter 4D.

[0134] That is, in this embodiment, the actual rotation speed Fr acquired by the electric motor inverter 4D is not used as the corrected rotation speed Fc, but the estimated rotation speed estimated by calculation in the rotation speed estimation unit 56 of the controller 5D is used as the corrected rotation speed Fc.

[0135] The estimated torque command section 57 generates a corrected torque command signal based on the estimated rotation speed estimated by the rotation speed estimating section 56, and outputs the corrected torque command signal to the electric motor inverter 4D.

[0136] Moreover, the electric motor inverter 4D according to this embodiment includes only a current command unit 44D. The current command unit 44D converts the correction torque command signal output from the controller 5D into a command current and outputs it to the electric motor .

[0137] 17, in parallel with the processing of steps S501 and S502, the controller 5D calculates the estimated rotation speed of the electric motor 34. Specifically, in parallel with step S501, the controller 5D acquires the current reference rotation speed Fs1 using the data acquisition unit 51, and reads the previous reference rotation speed Fs0 acquired previously from the storage unit 58 (step S507).

[0138] Next, the rotation speed estimation unit 56 calculates the rotation acceleration of the electric motor 34 based on the current reference rotation speed Fs1 acquired in step S507 and the previous reference rotation speed Fs0 read in step S507 (step S508).

[0139] In addition, in parallel with the processing of steps S501 and S507, the arrival time estimation unit 55 reads the update periods of the controller 5D and the electric motor inverter 4D and the communication delay time between the controller 5D and the electric motor inverter 4D from the memory unit 58 (step S509).

[0140] Next, the arrival time estimation unit 55 estimates the arrival time of the torque command signal based on the update periods and communication delay times read in step S509 (step S510).

[0141] Next, the rotation speed estimation unit 56 calculates an estimated rotation speed of the electric motor 34 based on the rotation acceleration of the electric motor 34 calculated in step S508 and the torque command signal arrival time estimated in step S510 (step S511).

[0142] Then, the estimated torque command unit 57 generates a corrected torque command signal based on the estimated rotational speed estimated by the rotational speed estimator 56 (step S512), and outputs the corrected torque command signal to the electric motor inverter 4D (step S513). After completing the process of step S513, the controller 5D returns to step S501, step S507, and step S509 to repeat the process.

[0143] With the controller 5D and electric motor inverter 4D according to this embodiment, an estimated rotation speed equivalent to the corrected rotation speed Fc is calculated on the controller 5D side, and a corrected torque command signal is generated based on the estimated rotation speed and output to the electric motor inverter 4D, so there is no need for the electric motor inverter 4D side to recalculate the corrected torque Trc, thereby reducing the load on the CPU of the electric motor inverter 4D. Furthermore, this embodiment also provides the same functions and effects as those of the first embodiment.

[0144] Sixth Embodiment Next, a controller 5 and an electric motor inverter 4E according to a sixth embodiment of the present invention will be described with reference to FIGS.

[0145] Fig. 18 is a functional block diagram showing the functions of the controller 5 and the electric motor inverter 4E according to the sixth embodiment, and Fig. 19 is a flowchart showing the flow of processing executed by the electric motor inverter 4E according to the sixth embodiment.

[0146] The controller 5 according to this embodiment has the same functions as the controller 5 according to the first embodiment, so a description of the controller 5 will be omitted and the following description will mainly focus on the electric motor inverter 4E.

[0147] As shown in FIG. 18, the electric motor inverter 4E includes a data acquisition unit 41E, a power consumption calculation unit 42, a correction torque command unit 43E, a current command unit 44, a memory unit 45, and an excavation determination unit 47.

[0148] The excavation determination unit 47 included in the electric motor inverter 4E according to this embodiment determines whether the work implement 2 is performing excavation or not based on the amount of operation of the operating lever 122 acquired by the data acquisition unit 41E. When the work implement 2 is performing excavation, the lift arm 21 is in a position lower than the horizontal position, and the angle of the bucket 23 is horizontal.

[0149] When the excavation determination unit 47 determines that the work implement 2 is performing excavation, the correction torque command unit 43E calculates a correction torque Trc based on the power consumption of the electric motor 34 calculated by the power consumption calculation unit 42 and the actual rotation speed Fr acquired by the data acquisition unit 41, and outputs a correction torque command signal to the current command unit 44.

[0150] On the other hand, when excavation determination unit 47 determines that working implement 2 is not performing excavation, correction torque command unit 43E outputs the reference torque command signal output from controller 5 to current command unit 44.

[0151] As shown in FIG. 19, the processes of steps S401, S402, S403, and S404 for the electric motor inverter 4E are similar to those for the electric motor inverter 4 according to the first embodiment.

[0152] After calculating the power consumption of the electric motor 34 in step S404, the data acquisition unit 41E acquires the operation amount of the operating lever 122 detected by the operation amount sensor 122A (step S414).

[0153] Next, the excavation determination unit 47 determines whether the working device 2 is performing excavation based on the amount of operation of the operating lever 122 acquired in step S414 (step S415). If it is determined in step S415 that the working device 2 is performing excavation (step S415 / YES), the process proceeds to steps S405, S406, S407, and S408 in that order, and the current command unit 44 converts the corrected torque command signal into a command current and outputs it to the electric motor 34.

[0154] On the other hand, if it is not determined in step S415 that the work implement 2 is performing excavation (step S415 / NO), the process proceeds to step S410 and step S411, where the current command unit 44 converts the reference torque command signal into a command current and outputs it to the electric motor 34.

[0155] According to the electric motor inverter 4E of this embodiment, control is performed on the electric motor 34 based on the correction torque Trc when excavation work is being performed, which is particularly prone to engine 31 stall and wheel slip, and when excavation work is not being performed, the process of calculating the correction torque Trc can be omitted, thereby preventing an unnecessary load from being placed on the CPUs of the controller 5 and the electric motor inverter 4E. Furthermore, this embodiment also provides the same functions and effects as those of the first embodiment.

[0156] The above describes each embodiment of the present invention. Note that the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of this embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of this embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of this embodiment with other configurations.

[0157] For example, in the above embodiment, a wheel loader 1 was described as one type of work vehicle, but the present invention is not limited to this, and may be a work vehicle other than the wheel loader 1 as long as it has a work implement 2 attached to the vehicle body. [Explanation of symbols]

[0158] 1: Wheel loader (work vehicle) 2: Work equipment 4, 4A, 4B, 4C, 4D, 4E: Inverter for electric motor 5, 5A, 5C, 5D: Controller 10L, 10R: Steering cylinder (hydraulic cylinder) 11: Wheels 22: Lift arm cylinder (hydraulic cylinder) 24: Bucket cylinder (hydraulic cylinder) 31: Engine 32: Generator 34: Electric motor 34A: Rotational speed sensor (rotational speed detection device) 61: Hydraulic pump 121: Accelerator pedal 121A: Pedal amount sensor (pedal amount detection device) 122: Operating lever (operating device) 122A: Operation amount sensor (operation amount detection device) Fc: Corrected rotation speed Fr: Actual rotation speed Fs: Reference rotation speed

Claims

1. a vehicle body provided with a plurality of wheels; a working device attached to a frame constituting the vehicle body; an engine mounted on the vehicle body; an operating device for operating the working device; a hydraulic cylinder that drives the working device based on the amount of operation of the operating device; a hydraulic pump driven by the engine to supply hydraulic oil to the hydraulic cylinder; an accelerator pedal for controlling the driving force of the vehicle body; a generator driven by the engine; an electric motor that converts the electric power generated by the generator into rotational power and transmits the rotational power to the plurality of wheels; an electric motor inverter that calculates torque generated by the electric motor and controls current; a controller that outputs a command signal related to power consumption to be consumed by the electric motor to the electric motor inverter; a depression amount detection device for detecting the depression amount of the accelerator pedal; a rotational speed detection device for detecting the rotational speed of the electric motor; an operation amount detection device that detects an operation amount of the operation device; In a work vehicle equipped with The controller acquiring the rotational speed of the electric motor detected by the rotational speed detection device as a reference rotational speed at each update period of the controller; calculating the consumed power to be consumed by the electric motor out of the available output power of the engine based on the depression amount of the accelerator pedal detected by the depression amount detection device and the operation amount of the operation device detected by the operation amount detection device; generating, as the command signal, a reference torque command signal relating to a reference torque of the electric motor based on the calculated consumed power and the reference rotation speed acquired at an update period of the controller; outputting the generated reference torque command signal and the reference rotation speed obtained at an update period of the controller to the electric motor inverter; The electric motor inverter comprises: acquiring the latest rotational speed of the electric motor detected by the rotational speed detection device as an actual rotational speed that matches the actual rotational speed of the electric motor; calculating the power consumption to be consumed by the electric motor based on the reference torque command signal and the reference rotational speed output from the controller; calculating a command current value related to a torque generated by the electric motor based on the calculated consumed power and the acquired actual rotation speed; A current having the calculated command current value is output to the electric motor. A work vehicle characterized by:

2. A vehicle body provided with a plurality of wheels; a working device attached to a frame constituting the vehicle body; an engine mounted on the vehicle body; an operating device for operating the working device; a hydraulic cylinder that drives the working device based on the amount of operation of the operating device; a hydraulic pump driven by the engine to supply hydraulic oil to the hydraulic cylinder; an accelerator pedal for controlling the driving force of the vehicle body; a generator driven by the engine; an electric motor that converts the electric power generated by the generator into rotational power and transmits the rotational power to the plurality of wheels; an electric motor inverter that calculates torque generated by the electric motor and controls current; a controller that outputs a command signal related to power consumption to be consumed by the electric motor to the electric motor inverter; a depression amount detection device for detecting the depression amount of the accelerator pedal; a rotational speed detection device for detecting the rotational speed of the electric motor; an operation amount detection device that detects an operation amount of the operation device; In a work vehicle equipped with The controller calculating the consumed power to be consumed by the electric motor out of the available output power of the engine based on the depression amount of the accelerator pedal detected by the depression amount detection device and the operation amount of the operation device detected by the operation amount detection device; outputting the command signal based on the calculated consumed power to the electric motor inverter; The electric motor inverter comprises: determining whether or not the rotation speed of the electric motor has suddenly changed based on the rotation speed of the electric motor detected by the rotation speed detection device; when it is determined that the rotation speed of the electric motor has suddenly changed, a command current value related to the torque generated by the electric motor is calculated based on the command signal output from the controller and a corrected rotation speed based on the rotation speed of the electric motor detected by the rotation speed detection device; When it is not determined that the rotation speed of the electric motor has suddenly changed, the command current value is calculated based on the command signal output from the controller; A current having the calculated command current value is output to the electric motor. A work vehicle characterized by:

3. The work vehicle according to claim 2, The electric motor inverter comprises: When it is determined that the rotation speed of the electric motor has suddenly changed, a flag related to the sudden change in the rotation speed of the electric motor is output to the controller. A work vehicle characterized by:

4. A vehicle body having a plurality of wheels; a working device attached to a frame constituting the vehicle body; an engine mounted on the vehicle body; an operating device for operating the working device; a hydraulic cylinder that drives the working device based on the amount of operation of the operating device; a hydraulic pump driven by the engine to supply hydraulic oil to the hydraulic cylinder; an accelerator pedal for controlling the driving force of the vehicle body; a generator driven by the engine; an electric motor that converts the electric power generated by the generator into rotational power and transmits the rotational power to the plurality of wheels; an electric motor inverter that calculates torque generated by the electric motor and controls current; a controller that outputs a command signal related to power consumption to be consumed by the electric motor to the electric motor inverter; a depression amount detection device for detecting the depression amount of the accelerator pedal; a rotational speed detection device for detecting the rotational speed of the electric motor; an operation amount detection device that detects an operation amount of the operation device; In a work vehicle equipped with The controller calculating the consumed power to be consumed by the electric motor out of the available output power of the engine based on the depression amount of the accelerator pedal detected by the depression amount detection device and the operation amount of the operation device detected by the operation amount detection device; acquiring and storing the rotational speed of the electric motor detected by the rotational speed detection device as a reference rotational speed; calculating a rate of change of the reference rotation speed based on the acquired current reference rotation speed and the stored previous reference rotation speed; calculating an estimated rotation speed as the rotation speed of the electric motor when the command signal output from the controller is input to the electric motor inverter, based on the calculated rate of change, an update cycle of the controller, and a delay time in communication between the controller and the electric motor inverter; generating, as the command signal, a reference torque command signal relating to a reference torque of the electric motor based on the calculated consumed power and the estimated rotation speed; outputting the generated reference torque command signal to the electric motor inverter; The electric motor inverter comprises: calculating a command current value related to the torque generated by the electric motor based on the command signal output from the controller; A current having the calculated command current value is output to the electric motor. A work vehicle characterized by:

5. A vehicle body having a plurality of wheels; a working device attached to a frame constituting the vehicle body; an engine mounted on the vehicle body; an operating device for operating the working device; a hydraulic cylinder that drives the working device based on the amount of operation of the operating device; a hydraulic pump driven by the engine to supply hydraulic oil to the hydraulic cylinder; an accelerator pedal for controlling the driving force of the vehicle body; a generator driven by the engine; an electric motor that converts the electric power generated by the generator into rotational power and transmits the rotational power to the plurality of wheels; an electric motor inverter that calculates torque generated by the electric motor and controls current; a controller that outputs a command signal related to power consumption to be consumed by the electric motor to the electric motor inverter; a depression amount detection device for detecting the depression amount of the accelerator pedal; a rotational speed detection device for detecting the rotational speed of the electric motor; an operation amount detection device that detects an operation amount of the operation device; In a work vehicle equipped with The controller The rotation speed of the electric motor detected by the rotation speed detection device is set as a reference rotation speed. and acquires the data at each update cycle of the controller; calculating the consumed power to be consumed by the electric motor out of the available output power of the engine based on the depression amount of the accelerator pedal detected by the depression amount detection device and the operation amount of the operation device detected by the operation amount detection device; generating, as the command signal, a reference torque command signal relating to a reference torque of the electric motor based on the calculated consumed power and the reference rotation speed acquired at an update period of the controller; outputting the generated reference torque command signal and the reference rotation speed obtained at an update period of the controller to the electric motor inverter; The electric motor inverter comprises: acquiring the latest rotational speed of the electric motor detected by the rotational speed detection device as an actual rotational speed that matches the actual rotational speed of the electric motor; determining whether the work device is performing excavation based on the operation amount of the operation device detected by the operation amount detection device; When it is determined that the working device is performing excavation, the power consumption to be consumed by the electric motor is calculated based on the reference torque command signal and the reference rotational speed output from the controller; calculating a command current value related to a torque generated by the electric motor based on the calculated consumed power and the acquired actual rotation speed; When it is not determined that the working device is performing excavation, the command current value is calculated based on the reference torque command signal output from the controller; A current having the calculated command current value is output to the electric motor. A work vehicle characterized by:

Images