JP2024000279A - electric work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric work vehicle configured so that output of a battery for running the vehicle can be managed properly, even when cell voltages of battery cells constituting the battery for running cannot be detected.

SOLUTION: An electric work vehicle is provided with: an electric motor 1; a battery 4 for running the vehicle constituted of a plurality of battery cells 40; an inverter 14 that supplies electric power for driving to the electric motor 1 using electric power from the battery 4 for running; a cell voltage detector 51 that detects cell voltages of the battery cells 40; and a control device 6 that when the cell voltage detector 51 cannot detect at least one cell voltage, stops output of the electric motor 1 or restricts output of the electric motor 1 to a preset limit output value, on the basis of a power supply state of the battery 4 for running.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to an electric working vehicle that avoids overcharging and overdischarging of a battery and suppressing unexpected stops by managing the charging/discharging state of the battery.

Patent Document 1 describes a voltage sensor that detects the electromotive force (cell voltage) of each of a plurality of battery units (battery cells) that constitute a battery, voltage sensor failure detection means that detects a failure of the voltage sensor, and battery current detection means that detects a failure of the voltage sensor. A battery management device is disclosed having a suppression means. This battery current suppressing means suppresses the battery current when a failure of any one of the voltage sensors is detected. Thereby, even if an abnormality occurs in the battery unit, heat generation due to Joule heat is suppressed, and further deterioration of the battery unit is prevented.

Japanese Patent Application Publication No. 2000-357541

In the battery management device according to Patent Document 1, when a failure of a voltage sensor that detects the voltage of a battery unit is detected by a voltage sensor failure detection means, the battery current is suppressed. However, since limited power is supplied from the battery to the motor, there is a risk that the battery unit to which the faulty voltage sensor is assigned may be fatally over-discharged or over-charged during this time.

In view of these circumstances, an object of the present invention is to provide an electric working vehicle that can appropriately manage the output of a driving battery even when it becomes impossible to detect the cell voltage of a battery cell that constitutes a driving battery. The goal is to provide the following.

The electric working vehicle according to the present invention includes an electric motor driven for vehicle body movement, a driving battery including a plurality of battery cells, and supplying driving power to the electric motor using electric power from the driving battery. an inverter that detects the cell voltage of the battery cell, a cell voltage detector that detects the cell voltage of the battery cell, and when the cell voltage detector is unable to detect at least one of the cell voltages, based on the power supply state of the driving battery. and a control device for stopping the output of the electric motor or for limiting the output of the electric motor to a preset limit output value.

According to this configuration, when the cell voltage detector becomes unable to detect at least one of the cell voltages, either the output of the electric motor is stopped or the output of the electric motor is limited. At this time, if it is determined that there is a high possibility of fatal over-discharge or over-charging of the driving battery, the electric motor output is stopped and the vehicle is stopped. Then, the state of the running battery and the state of battery-related equipment such as a cell voltage detector are checked. In addition, if it is deemed that there is no serious over-discharge or overcharging of the traction battery, the electric motor output limit is selected, making it a suitable place to check the traction battery, cell voltage detector, etc. Electric work vehicles can travel to (parking lots, maintenance and inspection service centers, etc.).

Regardless of whether the electric motor output is stopped or the electric motor output is limited, it will greatly affect the running of the electric working vehicle, so it is impossible for the cell voltage detector to detect at least one cell voltage; It is preferable to notify the driver of the selection result (output stop or output restriction). Therefore, in the present invention, the driver is notified through the notification unit that the control device has decided to stop the output of the electric motor or to limit the output of the electric motor.

The battery state of the driving battery, which is a criterion for selecting whether to stop the output of the electric motor or limit the output of the electric motor, can be estimated based on, for example, the total inverter voltage of the inverter. For this reason, the present invention includes an inverter voltage detection section that detects the total inverter voltage of the inverter, and the control device is configured to detect when the total inverter voltage of the inverter deviates from a preset total inverter voltage tolerance range. In this case, the output of the electric motor is stopped. That is, if the total inverter voltage is, for example, a low voltage that indicates over-discharge of the driving battery, the vehicle body is stopped in order to avoid danger due to over-discharge. However, in order to avoid an unexpected stop at an inappropriate location, it is preferable to make the inverter total voltage tolerance range sufficiently large.

The battery state of the running battery, which is a criterion for selecting whether to stop the output of the electric motor or to limit the output of the electric motor, can also be estimated based on the input voltage of the DC/DC converter that is supplied with power from the running battery. For this reason, the present invention is provided with a DC/DC converter that is supplied with power from the driving battery, and the control device is configured to adjust the input voltage of the DC/DC converter from a preset allowable converter input voltage range. If it comes off, the output of the electric motor is stopped. Even in this configuration, it is preferable that the allowable range of converter input voltage be made sufficiently large with a margin in order to avoid unexpected stopping at an inappropriate location.

Since the basic element constituting a driving battery is a battery cell, when the cell voltage of one battery cell falls outside a predetermined range (cell voltage tolerance range), it has a serious effect on the state of the driving battery. In order to solve such problems and appropriately manage the output of the driving battery, the present invention provides that the control device controls the electric motor when the cell voltage deviates from a preset cell voltage tolerance range. The output is stopped or the output of the electric motor is limited to the limited output value. The cell voltage permissible range, like the inverter total voltage permissible range and the converter input voltage permissible range, is determined experimentally and empirically in consideration of the type of work vehicle and the like.

FIG. 3 is a left side view of the tractor. FIG. 3 is a left side view showing the arrangement of a motor and a running battery. FIG. 3 is a schematic diagram showing the flow of power transmission. FIG. 2 is a functional block diagram showing functional units of the battery system. 3 is a flowchart illustrating an example of battery management control. It is a flowchart which shows another example of battery management control.

Embodiments for carrying out the present invention will be described based on the drawings. In the following explanation, unless otherwise specified, the direction of arrow F in the figure is "front", the direction of arrow B is "rear", the direction of arrow L is "left", and the direction of arrow R is "front". Let's say "right". The direction of arrow U in the figure is "up" and the direction of arrow D is "down."

[Overall configuration of tractor]
Below, a tractor as an example of an electric working vehicle according to the present invention will be described. As shown in FIG. 1, the tractor includes left and right front wheels 10, left and right rear wheels 11, and a cover member 12.

The tractor includes a body frame 2 and a driving section 3. The body frame 2 is supported by left and right front wheels 10 and left and right rear wheels 11. The cover member 12 is arranged at the front of the fuselage. The driving section 3 is provided at the rear of the cover member 12.

The driver section 3 includes a protective frame 30, a driver's seat 31, and a steering wheel 32. A steering wheel 32 is provided so as to be operable by a driver seated on a driver's seat 31 in the driving section 3. By operating the steering wheel 32, the left and right front wheels 10 are steered. The driver can perform various driving operations in the driving section 3.

The tractor is equipped with a running battery 4. The cover member 12 is configured to be swingable around an opening/closing axis Q along the left-right direction of the machine body. Thereby, the cover member 12 is configured to be openable and closable. When the cover member 12 is in the closed state, the driving battery 4 is covered by the cover member 12.

As shown in FIG. 2, the tractor includes an inverter 14 and an electric motor 1. The running battery 4 supplies power to the inverter 14 . The inverter 14 converts DC power from the driving battery 4 into AC power to generate driving power to be supplied to the electric motor 1 . The driving power is AC power generated from the inverter 14.

As shown in FIGS. 2 and 3, the tractor includes a hydrostatic continuously variable transmission 15 and a transmission 16. As shown in FIG. 3, the hydrostatic continuously variable transmission 15 includes a hydraulic pump 15a and a hydraulic motor 15b.

The hydraulic pump 15a is driven by rotational power from the electric motor 1. When the hydraulic pump 15a is driven, rotational power is output from the hydraulic motor 15b. Note that the hydrostatic continuously variable transmission 15 is configured so that the rotational power is variable in speed between the hydraulic pump 15a and the hydraulic motor 15b.

The rotational power output from the hydraulic motor 15b is transmitted to the transmission 16. The rotational power transmitted to the transmission 16 is shifted by a gear type transmission mechanism included in the transmission 16 and distributed to the left and right front wheels 10 and the left and right rear wheels 11. As a result, the left and right front wheels 10 and the left and right rear wheels 11 are driven.

As shown in FIGS. 2 and 3, the tractor includes a mid PTO shaft 17 and a rear PTO shaft 18. Rotational power output from the electric motor 1 is distributed to the hydraulic pump 15a, the mid PTO shaft 17, and the rear PTO shaft 18. As a result, the mid PTO shaft 17 and the rear PTO shaft 18 rotate.

If a working device is connected to the mid PTO shaft 17 or the rear PTO shaft 18, the working device will be driven by the rotational power of the mid PTO shaft 17 or the rear PTO shaft 18. For example, as shown in FIG. 2, in this embodiment, a grass cutting device 19 is connected to the mid PTO shaft 17. The mowing device 19 is driven by the rotational power of the mid PTO shaft 17.

[Motor/battery control system configuration]
FIG. 4 schematically shows a configuration related to control of the driving battery 4 and the electric motor 1. The motor/battery control system includes an accelerator device 33 , a key controller 34 , a control device 6 that controls the operation of the electric motor 1 , and an inverter 14 . The accelerator device 33 is provided near the steering wheel 32. Although not shown, the accelerator device 33 includes a swingable lever and a potentiometer that is operated by swinging the lever. The accelerator device 33 is connected to the control device 6. The key controller 34 is also connected to the control device 6, and provides the control device 6 with a key operation signal based on the movement of a main key operated by the driver. The control device 6 is connected to the inverter 14 and gives a drive command to the inverter 14 in response to a command from the accelerator device 33. The inverter 14 controls the output of the electric motor 1 by adjusting the electric power supplied from the driving battery 4 to the electric motor 1 according to a command from the control device 6 .

The control device 6 is also connected to the notification unit 35. The notification unit 35 is a general term for devices such as operation panels, meter panels, lamps, and buzzers that notify information to the driver. ), etc., visually or audibly.

The running battery 4 can be charged from an external power source 44 via a charging section 43 . The charging section 43 is provided with a power supply socket (not shown). The power supply socket can be connected to a power supply connector (not shown) of a charging cable from the external power source 44. The power supply socket is arranged inside the cover member 12, and is exposed to the outside when the cover member 12 is swung open. The control device 6 controls the driving of the inverter 14 and also controls the charging of the driving battery 4 by the charging section 43.

The driving battery 4 is, for example, a lithium ion battery, and is configured by stacking a large number of battery cells 40, which are small, low-voltage unit batteries. The running battery 4 is housed with the outside covered in a sealed state by a storage case.

A battery voltage detection section 5 is provided to detect the battery voltage of the driving battery 4. In this embodiment, the battery voltage detection unit 5 includes a cell voltage detector 51 that detects the voltage at the connection point between the plurality of battery cells 40 connected in series as a cell voltage. In FIG. 4, the cell voltage detector 51 is configured to detect the cell voltage of each battery cell 40, but it is configured to detect the cell voltage of two or more battery cells 40 as one unit. It may be configured as follows. The cell voltage detected by the cell voltage detector 51 is input to the control device 6. Although not shown, a temperature detection sensor for detecting the temperature of the battery cell 40 and other internal temperatures of the driving battery 4 is also provided, and its detection signal is also input to the control device 6.

In addition to the driving battery 4, the tractor is equipped with an electrical component battery 41 that supplies power to the control device 6 and other electrical components. The electrical component battery 41 supplies low voltage (12 volts) power to drive electrical components. The electrical component battery 41 is charged with electric power supplied from the driving battery 4 via the DC/DC converter 42 . The DC/DC converter 42 is driven and controlled by the control device 6.

When the cell voltage detector 51 is unable to detect at least one cell voltage, the control device 6 stops the output of the electric motor 1 or stops the output of the electric motor 1 based on the power supply state of the driving battery 4. It has the function of limiting the output of the output to a preset limit output value. To realize this function, the control device 6 includes a battery management section 60, an inverter voltage detection section 61, and a DC/DC converter voltage detection section in order to manage the output (discharge) of the driving battery 4 according to the state of charge. 62 and a motor drive management section 63.

The inverter voltage detection section 61 detects the total inverter voltage of the inverter 14. The DC/DC converter voltage detection section 62 detects the converter input voltage of the DC/DC converter 42. In FIG. 4, the inverter voltage detection section 61 and the DC/DC converter voltage detection section 62 are provided inside the control device 6, but they may be provided outside the control device 6. The battery management unit 60 manages charging and discharging of the driving battery 4 based on the cell voltage, the total inverter voltage, the converter input voltage, the signal from the accelerator device 33, the signal from the key controller 34, and the like. Motor drive management section 63 generates a drive signal for driving electric motor 1 based on the signal from accelerator device 33 and provides it to inverter 14 .

When a charging command is input to the control device 6 with the plug of the power cable from the external power source 44 inserted into the socket of the charging unit 43, the charging program is executed and the driving battery 4 is charged.

The control device 6 determines whether to stop the output of the electric motor 1 or limit the output of the electric motor 1 based on a control rule set in advance, and the driver is notified of the determination through the notification unit 35.

When the cell voltage detector 51 is unable to detect the cell voltage of at least one battery cell 40, the control device 6 limits the output of the electric motor 1 to a preset limit output value. Even if the cell voltage cannot be detected, it does not necessarily mean that the state of the battery cell 40 is abnormal; however, as a safety measure, first limit the output of the electric motor 1 to prevent an unexpected abnormality of the battery cell 40. In other words, a remedy for the abnormality of the driving battery 4 is taken. Furthermore, it is determined whether or not the driving battery 4 is abnormal by a secondary method other than cell voltage detection by the cell voltage detector 51, and based on the determination result, if necessary, a secondary method is used. As a relief measure, the output of the electric motor 1 is stopped.

An example of a determination rule for determining this secondary relief measure, that is, stopping the output of the electric motor 1 in this embodiment, is as follows.
(1) When the total inverter voltage deviates from the preset total inverter voltage tolerance range, the control device 6 stops the output of the electric motor 1.
(2) When the input voltage of the DC/DC converter 42 deviates from the preset converter input voltage tolerance range, the control device 6 stops the output of the electric motor 1.

Even if the cell voltage detector 51 becomes unable to detect the cell voltage of at least one battery cell 40, it does not necessarily mean that the cell voltage of all the battery cells 40 becomes impossible to detect. may determine whether to limit the output of the electric motor 1 or stop the output of the electric motor 1 from the cell voltage of the battery cell 40 whose cell voltage can be detected. That is, if the cell voltage deviates from the preset cell voltage tolerance range, the control device 6 stops the output of the electric motor 1 or limits the output of the electric motor 1 to the preset limit output value. .

Next, an example of management processing of the driving battery 4 (output management of the electric motor 1) by the control device 6 configured as described above will be described with reference to the flowchart of FIG. 5.

When this battery management process is started, the control device 6 checks whether there is even one battery cell 40 whose cell voltage cannot be detected (#01). This cell voltage undetectable check can be performed based on the detection result of the cell voltage detector 51. If the battery cell 40 whose cell voltage cannot be detected is not detected in the cell voltage undetectable check (#01 No branch), the detected cell voltage is within the preset cell voltage tolerance range (overcharged or overdischarged). It is checked whether there is any battery cell 40 that is out of the state (#02). In this cell voltage out of permissible range check, if all cell voltages are within the cell voltage permissible range (#02 No branch), the battery condition of the driving battery 4 is considered to be normal (#03), Motor output control for the electric motor 1 is performed normally (#04).

In the cell voltage undetectable check in step #01, if at least one battery cell 40 whose cell voltage cannot be detected is detected (#01 Yes branch), the control device 6 detects a battery cell 40 whose cell voltage cannot be detected. This is notified through the notification unit 35 (#10). Further, the control device 6 uses the function of the inverter voltage detection unit 61 to check whether the total inverter voltage is outside a preset allowable total inverter voltage range (#11). In this inverter total voltage check, if the inverter total voltage is within the inverter total voltage allowable range (#11 No branch), although it is impossible to detect the cell voltage, the driving battery 4 will remain active for at least a while. is considered to be usable (#13). However, since the condition of the driving battery 4 is likely to deteriorate in the future, the control device 6 limits the motor output to the electric motor 1 so that it does not exceed a preset output limit value (#14). . At the same time, the control device 6 notifies the electric motor 1 through the notification unit 35 that motor output control is to be performed (#15). This notification allows the driver to move the tractor to a location suitable for maintenance or inspection, such as a barn or repair center, without having to make an unexpected stop.

In the cell voltage out of permissible range check in step #02, if even one cell voltage is out of the cell voltage permissible range (#02 Yes branch), the driving battery 4 is deemed to be abnormal (#20). In other words, if at least one battery cell 40 whose cell voltage cannot be detected is detected, and even one cell voltage is outside the permissible cell voltage range, the driving battery 4 is considered to be abnormal, and the Motor output control for motor 1 is stopped (#21). Further, the control device 6 notifies via the notification unit 35 that the motor output control for the electric motor 1 will be stopped since the driving battery 4 is deemed to be abnormal (#22).

Similarly, in the inverter total voltage check in step #11, if the inverter total voltage is outside the inverter total voltage tolerance range (#11 Yes branch), the power supply by the running battery 4 is insufficient, and the running battery 4 is deemed to be abnormal (#20), and motor output control for the electric motor 1 is stopped (#21). Since the control device 6 considers that the driving battery 4 is abnormal, it notifies via the notification unit 35 that the motor output control for the electric motor 1 will be stopped (#22).

Next, another example of the management process for the driving battery 4 (the output management process for the electric motor 1), which is different from the flowchart in FIG. 5, will be described with reference to the flowchart in FIG.

In the management process shown in FIG. 6, unlike the management process shown in FIG. 5, instead of checking whether the total inverter voltage in step #11 of FIG. 12, the control device 6 uses the function of the DC/DC converter voltage detection section 62 to check whether the converter input voltage is outside a preset converter input voltage tolerance range. Then, in this converter input voltage check, if the converter input voltage is within the converter input voltage tolerance range (#12 No branch), although it is impossible to detect the cell voltage, the driving battery 4 will be charged at least for a while. The remaining time is considered to be usable (#13). In the converter input voltage check in step #12, if the converter input voltage is outside the allowable converter input voltage range (#12 Yes branch), the power supply by the running battery 4 is insufficient, and the running battery 4 is abnormal. (#20). Otherwise, the flowchart of FIG. 6 is the same as the flowchart of FIG. 5. That is, in the management process shown in FIG. 6, a check of the converter input voltage is adopted instead of checking the inverter total voltage in the management process shown in FIG.

As a further management process for the driving battery 4, a management process that combines the flowchart in FIG. 5 and the flowchart in FIG. 6, that is, checking the inverter total voltage in step #11 in FIG. Management processing that incorporates both checking of converter input voltage is also possible. In such a management process, if the total inverter voltage is not outside the permissible range and the converter input voltage is not outside the permissible range, the driving battery 4 is considered to be usable at least for a while. If either the total inverter voltage or the converter input voltage is outside the permissible range, the driving battery 4 is considered to be abnormal.

In the above-described flowchart of the management process for the driving battery 4, if there is at least one battery cell 40 whose cell voltage cannot be detected, and at least one of the remaining battery cells 40 whose cell voltage can be detected, the cell voltage is If the cell voltage is outside the allowable range, that is, if the branch is YES in step #02, the motor output control has been stopped. Instead, the cell voltage tolerance range is composed of a first tolerance range and a second tolerance range, and when the cell voltage deviates from the second tolerance range, motor output control is stopped and the cell voltage falls within the second tolerance range. However, if it deviates from the first tolerance range, a configuration may be adopted that limits the motor output. Furthermore, a configuration may be adopted in which, when a Yes branch is made in step #02, the process jumps to step #11 (FIG. 5) or step #12 (FIG. 6).

In the cell voltage undetectable check in step #01, if even one battery cell 40 whose cell voltage cannot be detected is detected, it is determined that the cell voltage cannot be detected, but two or more small battery cells 40 It may be determined that the cell voltage cannot be detected if the cell voltage cannot be detected.

[Another embodiment]
(1) In the above embodiment, the driving battery 4 was arranged in front of the driving section 3, but instead of this, it may be arranged below the driving section 3 or behind the driving section 3, It may be divided into multiple parts and placed in different locations.

(2) Judgment criteria for cell voltage permissible range, inverter total voltage permissible range, converter input voltage permissible range, etc. are based on whether the tractor is equipped with working equipment such as the mowing device 19 or tilling device, and when it is not installed. It may be changed depending on the non-equipped state, or may be changed depending on the type of the attached working device.

Note that the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with the configurations disclosed in other embodiments as long as there is no contradiction, and The embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the purpose of the present invention.

The present invention is applicable not only to tractors but also to various electric working vehicles such as rice transplanters, combines, and construction machinery.

1: Electric motor 14: Inverter 35: Notification unit 4: Running battery 40: Battery cell 41: Electrical component battery 42: DC/DC converter 43: Charging section 44: External power source 5: Battery voltage detection section 51: Cell voltage Detector 6: Control device 60: Battery management section 61: Inverter voltage detection section 62: DC/DC converter voltage detection section 63: Motor drive management section

Claims (5)

An electric motor that is driven to drive the vehicle;
A driving battery consisting of multiple battery cells,
an inverter that supplies driving power to the electric motor using power from the running battery;
a cell voltage detector that detects the cell voltage of the battery cell;
When the cell voltage detector is unable to detect at least one of the cell voltages, the output of the electric motor is stopped or the output of the electric motor is accelerated based on the power supply state of the driving battery. a control device that limits the output to a set limit output value;
An electric work vehicle equipped with The electric working vehicle according to claim 1, wherein the driver is notified through a notification unit that the control device has decided to stop the output of the electric motor or to limit the output of the electric motor. An inverter voltage detection section that detects a total inverter voltage of the inverter is provided,
The electric working vehicle according to claim 1, wherein the control device stops the output of the electric motor when the total inverter voltage of the inverter deviates from a preset total inverter voltage tolerance range. A DC/DC converter is provided that receives power from the running battery,
The electric working vehicle according to claim 1, wherein the control device stops the output of the electric motor when the input voltage of the DC/DC converter deviates from a preset converter input voltage tolerance range. 2. The control device according to claim 1, wherein the control device stops the output of the electric motor or limits the output of the electric motor to the limited output value if the cell voltage deviates from a preset cell voltage tolerance range. 4. The electric work vehicle according to any one of 4.

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