JP2023152732A - electric work vehicle - Google Patents

Abstract

To achieve protection of a battery and improvement of working efficiency in an electric work vehicle.SOLUTION: An electric work vehicle includes at least one motor configured to drive one or both of a travelling part and a working part included in the vehicle; an operation section 32 configured to direct a rotational speed or actuation of the motor; a control section 100 configured to control the motor according to operation of the operation part 32; and a battery 82 configured to supply electric power to the motor. The control section 100 decreases an upper limit of the rotational speed of the motor based on a detected result of a battery condition including a voltage of the battery.SELECTED DRAWING: Figure 3

Description

The present invention relates to an electric work vehicle that includes a traveling section and a working section.

2. Description of the Related Art Work vehicles equipped with a work section have been known in the past. For example, lawn mowing vehicles equipped with a lawn mower as a working unit that is driven to perform lawn mowing work are conventionally known. Further, among such work vehicles, an electric work vehicle is also being considered that includes a travel motor that is an electric motor that drives a travel portion such as a wheel, and a work motor that is an electric motor that drives a work portion.

For example, Patent Document 1 describes an electric work vehicle in which running motors, which are left and right electric motors, drive wheels on the corresponding side, and a blade motor (work motor) drives a rotating blade of a lawn mowing unit (work part). is listed.

In the vehicle described in Patent Document 1, the temperature sensor further detects the temperature of the blade motor, and when the detected temperature of the temperature sensor is higher than the threshold value, the exceptional speed control section controls the speed control unit to set the target determined by the left and right control levers. The travel motor is driven so that the vehicle travels at an exceptional speed lower than the travel speed. It is said that this makes it possible to protect the blade motor.

Patent No. 6121213

By the way, in an electric work vehicle that includes at least one motor that drives one or both of a traveling section and a working section, if the load on the battery that supplies power to the motor becomes high, the life of the battery may be shortened. Further, if the upper limit of the power supplied to the motor is always kept low with a sufficient margin from the viewpoint of battery protection, this will lead to a decrease in work efficiency. Thereby, it is desired to achieve both protection of the battery and improvement of work efficiency.

In addition, when controlling the running of a vehicle equipped with a running motor that drives the running section and a work motor that drives the working section, when controlling the running according to the torque generated by each motor, the discharge current from the battery is May rise excessively. When the discharge current of the battery exceeds the allowable upper limit value, processing such as cutting off the current flowing from the battery to each motor is performed in order to protect the battery. Therefore, when the vehicle suddenly stops, the efficiency of work using the work section is greatly reduced.

An object of the present invention is to achieve both protection of a battery and improvement of work efficiency in an electric work vehicle.

A first electric work vehicle according to the present invention includes at least one motor that drives one or both of a traveling section and a working section provided in the vehicle, an operating section that instructs the rotational speed or operation of the motor, and the operating section. a control unit that controls the motor according to the operation of the motor; and a battery that supplies power to the motor, and the control unit controls the motor based on the detection result of the battery state including the voltage of the battery. This is an electric work vehicle that lowers the upper limit of rotation speed.

According to the first electric work vehicle, when the load on the battery becomes high, such as when the amount of change in voltage of the battery that supplies power to the motor increases, by lowering the upper limit of the rotational speed of the motor, Since the load on the battery can be reduced, it is possible to protect the battery and improve work efficiency at the same time.

In the first electric work vehicle, the control unit controls the motor when the amount of change in the voltage of the battery from the reference voltage or the magnitude of the rate of change with respect to the reference voltage is equal to or greater than a first threshold value. The upper limit of the rotational speed may be lowered to a set first rotational speed limit.

In the first electric work vehicle, the control unit sets the upper limit of the rotational speed of the motor depending on the amount of change from a reference voltage for each change in voltage of the battery or the magnitude of a rate of change with respect to the reference voltage. It may also be configured to adjust.

According to the above configuration, the battery can be protected while suppressing a decrease in work efficiency compared to a case where the target rotational speed is greatly reduced all at once.

In the first electric work vehicle, the battery state includes a remaining charge of the battery, and the control unit is configured to determine an amount of change from a reference voltage or a rate of change with respect to the reference voltage for each change in voltage of the battery. , the upper limit of the rotational speed of the motor may be adjusted depending on the remaining charge amount.

According to the above configuration, it is possible to achieve both battery protection and work efficiency improvement with higher precision.

The first electric work vehicle includes a battery monitoring device that monitors the battery state,
The control unit may be configured to lower an upper limit of a target rotational speed of the motor and lower an upper limit of an actual rotational speed based on a detection result of the battery state from the battery monitoring device.

In the first electric work vehicle, the at least one motor may be a travel motor that drives at least one of the travel sections and a work motor that drives at least one of the work sections.

A second electric work vehicle according to the present invention includes at least one motor that drives one or both of a traveling section and a working section included in the vehicle, an operating section that instructs the rotational speed or operation of the motor, and the operating section. a control unit that controls the motor according to the operation of the motor; and a battery that supplies power to the motor, and the control unit controls the motor based on the detection result of the battery state including the voltage of the battery. This is an electric work vehicle that lowers the upper limit of torque.

According to the above-mentioned second electric work vehicle, when the load on the battery becomes high, such as when the amount of change in the voltage of the battery that supplies power to the motor increases, the upper limit of the torque of the motor is lowered. Since the load on the battery can be reduced, it is possible to protect the battery and improve work efficiency at the same time.

A third electric work vehicle according to the present invention includes a travel motor that drives at least one travel section, a work motor that drives at least one work section, and a battery that supplies power to the travel motor and the work motor. the battery, the battery having a specified maximum discharge current, and a control unit that controls the travel motor and the work motor, the control unit controlling the discharge current of the battery while the work motor is being driven; is an electric work vehicle in which the rotational speed of the traveling motor is controlled so as not to exceed the maximum discharge current.

According to the third electric work vehicle described above, by controlling the rotational speed of the travel motor, it is possible to prevent the discharge current of the battery from exceeding the maximum discharge current while the work motor is being driven. Therefore, even if a process is performed to cut off the current flowing from the battery to each motor in order to protect the battery, it is possible to prevent the vehicle from suddenly stopping. This makes it possible to both protect the battery and improve work efficiency.

The third electric work vehicle may include a battery monitoring device that monitors the state of the battery, and the control unit may acquire the maximum discharge current from the battery monitoring device via the communication means.

According to the above configuration, when the battery type is changed, in order to set the maximum discharge current according to the battery type, the settings of the battery monitoring device can be changed, and the settings of the control unit can be changed. There's no need to.

In the third electric work vehicle, the travel motor is driven by a travel inverter, the work motor is driven by a work inverter, and the control unit is configured to transfer the discharge current to the battery obtained by the travel inverter. The calculation may be made from the sum of a detected value of a discharge current from the battery to the running inverter and a detected value of a discharge current from the battery to the working inverter, which is obtained by the working inverter.

According to the above configuration, in order to obtain the battery discharge current with the control unit, the current sensor that detects the battery discharge current and the control unit are connected only to the signal line dedicated to transmitting the detected value of the battery's actual discharge current. There is no need to connect.

The third electric work vehicle may include a battery monitoring device that monitors the state of the battery, and the control unit may acquire the discharge current from the battery monitoring device via a communication means.

According to the above configuration, in order to obtain the actual discharge current of the battery by the control unit, the current sensor that detects the discharge current of the battery and the control unit are connected to a signal line dedicated to transmitting the detected value of the actual discharge current of the battery. No need to connect only.

The third electric work vehicle may include a sensor that measures the discharge current of the battery, and the control unit may acquire the discharge current from the sensor via a communication means.

In any one of the first electric work vehicle, the second electric work vehicle, and the third electric work vehicle, the battery is configured such that a plurality of battery packs are detachably connected to a plurality of pack connection parts. The plurality of battery packs can be electrically connected in parallel, and each of the plurality of pack connection parts is connected to a forward converter that allows current to flow only in the direction of output from the corresponding battery pack. A configuration may also be used.

According to the above configuration, when outputting electric power from a plurality of battery packs to a load section, current can be outputted to the load section in order from the battery pack with the highest voltage among the plurality of battery packs. This eliminates the need to adjust the voltages of the plurality of battery packs in advance before outputting current from the battery to the load section. Therefore, the batteries can be charged without excessively adjusting the voltages and charging amounts of the plurality of battery packs.

In any one of the first electric work vehicle, the second electric work vehicle, and the third electric work vehicle, the battery is configured such that a plurality of battery packs are detachably connected to a plurality of pack connection parts. The plurality of battery packs can be electrically connected in parallel, and each of the plurality of pack connection parts has an output direction from the corresponding battery pack and an input direction to the corresponding battery pack by switching. The first configuration may be such that a bidirectional converter capable of passing a current is connected to both of the two.

According to the first configuration, by switching the bidirectional converter to enable bidirectional conduction, the battery can be charged by supplying power to the battery pack from the load side through power regeneration or the like.

The first configuration described above includes a voltage sensor that detects the voltage of each of the plurality of battery packs, and based on the detected value of the voltage sensor, the voltage of at least two or more of the plurality of battery packs is determined. A configuration may be adopted in which it is determined whether or not the voltages match.

According to the above configuration, when the voltages of at least two or more battery packs match, the bidirectional converter corresponding to the battery pack with the matched voltage is configured to be switched to enable bidirectional conduction. Therefore, when it is possible to supply power to the battery pack from the load section side, input/output of power between the battery packs can be prevented.

The first configuration described above includes a current sensor that detects a current value output from each of the plurality of battery packs, and based on the detected value of the current sensor, at least two or more of the plurality of battery packs are detected. A configuration may be adopted in which it is determined whether the voltages of the battery packs match.

According to the above configuration, when the voltages of at least two or more battery packs match, the bidirectional converter corresponding to the battery pack with the matched voltage is configured to be switched to enable bidirectional conduction. Therefore, when it is possible to supply power to the battery pack from the load section side, input/output of power between the battery packs can be prevented.

According to the electric work vehicle according to the present invention, it is possible to protect the battery and improve work efficiency at the same time.

1 is a perspective view of an electric work vehicle according to an embodiment of the present invention. 2 is a schematic configuration diagram of the vehicle in FIG. 1. FIG. FIG. 2 is a block diagram showing a control system of the vehicle in FIG. 1. FIG. FIG. 6 is a diagram illustrating an example of how the upper limit values of the battery voltage and the rotation speed of the traveling motor change over time in the embodiment. In another example of the embodiment, it is a diagram showing an example of the passage of time of the upper limit values of the battery voltage and the rotation speed of the traveling motor. In another example of the embodiment, it is a diagram showing an example of the passage of time of the battery voltage, the remaining charge level (SOC) of the battery, and the upper limit value of the rotation speed of the traveling motor. FIG. 7 is a diagram illustrating an example of a case where the upper limit rotation speed of the travel motor is lowered in terms of the relationship between the rotation speed of the travel motor and the designated position of the operating unit in the embodiment. In the embodiment, it is a diagram showing another example of lowering the upper limit rotation speed of the travel motor in terms of the relationship between the rotation speed of the travel motor and the designated position of the operating unit. 5 is a diagram corresponding to FIG. 4 in another example of the embodiment; FIG. It is a block diagram showing the control system of the vehicle of another example of an embodiment. In another example of the embodiment, it is a diagram showing an example of the discharge current from the battery to the deck motor and the discharge current to the travel motor, and the number of rotations of the deck motor and the travel motor over time. In another example of the embodiment, it is a diagram schematically showing a circuit configuration for supplying power from a battery to a traveling motor (or deck motor). In another example of the embodiment, it is a diagram schematically showing a circuit configuration for supplying power from a battery to a traveling motor (or deck motor). In another example of the embodiment, it is a diagram schematically showing a circuit configuration for supplying power from a battery to a traveling motor (or deck motor). In another example of the embodiment, it is a diagram schematically showing a circuit configuration for supplying power from a battery to a traveling motor (or deck motor).

Hereinafter, embodiments of the present invention will be described in detail using the drawings. In the following, we will explain the case where the electric work vehicle is a lawn mowing vehicle, but the electric work vehicle is not limited to this, and can be used for any one or more of snow removal work, excavation work, civil engineering work, and agricultural work. Other work vehicles may also be used. In addition, in the following, a case will be explained in which a left and right lever type operator having two left and right operation levers is used, but this is just an example, and the steering wheel is used as a turning indicator, The accelerator pedal may be used as an acceleration indicator. In the following, an electric working vehicle will be described that has wheels as a traveling section driven by a traveling motor and travels by driving the wheels, but the traveling section may be a crawler or the like. The shape, number, arrangement of parts, etc. described below are examples for explanation, and can be changed as appropriate according to the specifications of the electric work vehicle. Hereinafter, similar elements in all drawings will be denoted by the same reference numerals to omit or simplify redundant description.

1 to 4, an electric work vehicle 10 according to an embodiment will be described. Hereinafter, the electric work vehicle 10 will be referred to as a vehicle 10. FIG. 1 is a perspective view of a vehicle 10. FIG. 2 is a schematic configuration diagram of the vehicle 10. In addition, in the configurations of FIGS. 1 to 4, a case will be explained in which the left and right wheels 12 and 13 are arranged on the rear side and the caster wheels 15 and 16 are arranged on the front side, but the wheels are on the front side and the caster wheels are on the rear side. But that's fine.

The vehicle 10 is a self-propelled lawn mowing vehicle suitable for mowing lawns. The vehicle 10 has two left and right wheels, a left wheel 12 and a right wheel 13 (FIG. 2), caster wheels 15 and 16, a lawn mower 18 which is a working part, a left travel motor 30 and a right travel motor 31 (FIG. 2). 2), three deck motors 60 (FIG. 2) that are working motors, two left and right operating levers 22 and 23 that constitute the operating section 32, and a working section start switch 33 (FIG. 3). The vehicle 10 further includes two left and right running inverters 84 and 86, three deck inverters 88, a control device 40 (FIG. 3), a battery 82 (FIG. 2), and a battery monitoring device 90 (FIG. 3), which constitute the control unit 100. 3). The left travel motor 30, the right travel motor 31, and the deck motor 60 are each electric motors. Deck inverter 88 corresponds to a working inverter.

The left wheel 12 and the right wheel 13 are rear wheels supported on both left and right sides of the rear side of the main frame 20, which is a vehicle body, and are main drive wheels. The main frame 20 is made of metal such as steel and has a beam structure or the like. The main frame 20 includes side plate portions 20a and 20b extending substantially in the front-rear direction at both left and right ends, and a connecting portion 20c that connects the side plate portions 20a and 20b on both the left and right sides. A driver's seat 21 on which a driver sits is fixed on the upper side between the rear ends of the left and right side plates 20a and 20b.

In the main frame 20, two guide panels 26, 27 are fixed to the left and right sides of the driver's seat 21, and two left and right operation levers 22, 23 project upward from the two guide panels 26, 27, respectively. It is supported by the main frame 20. The left operation lever 22 corresponds to an acceleration instruction section that instructs the left travel motor 30 to accelerate, and the right operation lever 23 corresponds to an acceleration instruction section that instructs the right travel motor 31 to accelerate. The tip of each of the operating levers 22 and 23 is grasped by the driver and used to instruct the rotational direction and rotational speed of the left wheel 12 and right wheel 13. The left operating lever 22 is operated to instruct driving and acceleration of the left wheel 12 by changing the rotational speed instruction of the left wheel 12 so that the rotational speed becomes higher. The right operating lever 23 is operated to instruct driving and acceleration of the right wheel 13 by changing the rotational speed instruction of the right wheel 13 so that the rotational speed becomes higher. Each of the operating levers 22 and 23 is approximately L-shaped, and a grip portion 24 extending in the left-right direction is formed at the upper end. The grip portion 24 is grasped and operated by the driver. Each operating lever 22, 23 is swingable at its lower end about an axis along the left-right direction. Each control lever 22, 23 moves the motor 30 (or 31) on the same side as the control lever 22 (or 23) forward when it is tilted forward based on the N position, which is a neutral position close to the upright position. Instructs to drive at a target rotational speed per unit time (sec ⁻¹ ) corresponding to the target rotational speed. The target rotational speed may be set as a target rotational speed per minute (min ⁻¹ ). The operating levers 22 and 23 instruct that the higher the amount of inclination, the higher the target rotation speed. When the control levers 22 and 23 are tilted to the rear with respect to the N position, they drive the motor 30 (or 31) on the same side as the control lever 22 (or 23) at a target rotation speed corresponding to reverse movement. The higher the amount of fall, the higher the target rotational speed. Thereby, each operating lever 22, 23 instructs the target rotation speed of the corresponding travel motor 30, 31.

The swinging positions of the two left and right operating levers 22 and 23 in the front-rear direction are detected by a left lever sensor 50 and a right lever sensor 51 (FIG. 3), which are lever position sensors, respectively. Each lever sensor 50, 51 includes, for example, a potentiometer. Detection signals from each lever sensor 50, 51 are transmitted to the control device 40.

The two left and right caster wheels 15 and 16 are steering wheels supported by the front end of the main frame 20, and are also front wheels. Each caster wheel 15, 16 is provided apart from the left wheel 12 and the right wheel 13 in the longitudinal direction of the vehicle 10. Each of the caster wheels 15 and 16 is capable of free rotation of 360 degrees or more about an axis in the vertical direction (vertical direction in FIG. 1). Note that the configuration is not limited to two caster wheels disposed on the vehicle, and only one caster wheel, or three or more caster wheels may be disposed on the vehicle.

As shown in FIG. 2, the left travel motor 30 is connected to the left wheel 12 via a left reduction gear device 58 supported on the rear side of the main frame 20. As shown in FIG. The right travel motor 31 is connected to the right wheel 13 via a right reduction gear device 59 supported on the rear side of the main frame 20 . The left travel motor 30 and the right travel motor 31 are supported on the left side and the right side, respectively, on the rear side of the main frame 20.

A battery 82 (FIG. 3) is connected to the left travel motor 30 via a left travel inverter 84 (FIG. 3), and power is supplied from the battery 82. A battery 82 is connected to the right travel motor 31 via a right travel inverter 86 (FIG. 3), and power is supplied from the battery 82. The left travel motor 30 and the right travel motor 31 are, for example, three-phase motors. As shown in FIG. 2, the battery 82 is fixed to the upper surface side or the lower surface side of the main frame 20 behind the driver's seat 21.

As shown in FIGS. 1 and 2, the lawn mower 18 is supported below the longitudinally intermediate portion of the main frame 20. As shown in FIGS. Thereby, the lawn mower 18 is arranged between the caster wheels 15, 16 and the left and right wheels 12, 13 in the front-rear direction. The lawn mower 18 includes three lawn mowing blades 18a, 18b, and 18c (FIG. 2), which are rotary lawn mowing tools, arranged inside a mower deck 19, which is a cover. The mowing blades 18a, 18b, and 18c are covered on the upper side by a mower deck 19. Each lawn mowing blade 18a, 18b, 18c has a plurality of blade elements that rotate around an axis oriented in the vertical direction (the front and back directions of the paper in FIG. 2). This allows the blade element to rotate to break up and mow the grass. A corresponding deck motor 60 among the three deck motors 60, which are work motors, is connected to each of the three lawn mowing blades 18a, 18b, and 18c. A battery 82 is connected to each deck motor 60 via a deck inverter 88 (FIG. 3) that is an inverter for the corresponding deck motor 60, and power is supplied from the battery 82. Each deck motor 60 is, for example, a three-phase motor.

A lawn mower is a rotary tool for mowing lawns, and has a function of mowing grass, etc. by arranging, for example, a spiral blade on a rotating shaft parallel to the ground surface, and can also be configured to include a lawn mowing reel driven by a deck motor. good.

FIG. 3 is a block diagram showing the control system 80 of the vehicle 10. The control device 40 includes a start switch 35, a work unit start switch 33, two lever sensors 50 and 51 on the left and right, two travel inverters 84 and 86 on the left and right, a deck inverter 88, and two motor speed sensors 54 on the left and right. , 55 are connected. The starting switch 35 and the working unit starting switch are provided on or near one guide panel 26 (or 27) that guides one of the two left and right operating levers 22 and 23. The start switch 35 is provided so as to be operable by the user, and starts the control device 40 by supplying power from the battery 82 to the control device 40 based on the operation. The work unit start switch 33 is provided so as to be operable by the user, and switches between activation and deactivation of the lawn mower 18 based on the operation. When the lawn mower 18 is instructed to start, that is, turned on, by the working part start switch 33, the control device 40 controls a deck inverter 88, which will be described later, to continue rotating the deck motor 60 at a predetermined target rotation speed. Activate it.

Thereby, the operation unit 32 instructs the target rotation speeds of the two left and right travel motors 30 and 31, and also instructs the operation of the three deck motors 60. On the other hand, the vehicle is equipped with only one travel motor instead of the two left and right travel motors 30 and 31, and is equipped with only one work motor instead of the three deck motors 60, and the operation unit is configured to set the target of one travel motor. It may be configured to instruct the rotation speed and to instruct the operation of one work motor.

The control system 80 includes a starting switch 35, a working section starting switch 33, and an operating section 32 including two left and right operating levers 22, 23, two left and right lever sensors 50, 51, two left and right travel motors 30, 31, and It includes traveling inverters 84 and 86, two left and right motor speed sensors 54 and 55, three deck motors 60 and a deck inverter 88, three deck motor speed sensors 52, and a control device 40. Although only one deck motor 60, one deck inverter 88, and one deck motor speed sensor 52 are shown in FIG. 3, in reality three deck motors 60 are provided as shown in FIG. 2, so the control system At 80, three deck inverters 88 and three deck motor speed sensors 52 are provided correspondingly.

The left travel inverter 84 drives the left travel motor 30, and the right travel inverter 86 drives the right travel motor 31. Each running inverter 84, 86 has, for example, a running inverter circuit including three arms each having two switching elements electrically connected in series, and a running inverter control device that controls the running inverter circuit.

The operation of each travel inverter 84, 86 is controlled by control device 40. Thereby, the left travel motor 30 is controlled by the control device 40 via the left travel inverter 84. The right travel motor 31 is controlled by the control device 40 via the right travel inverter 86 . Therefore, the rotation direction and rotation speed of the left travel motor 30 and the right travel motor 31 are independently controlled by the control device 40. Therefore, the left travel motor 30 and the right travel motor 31 independently drive the left wheel 12 and the right wheel 13 in terms of rotation direction and rotation speed.

Furthermore, the detected value of the rotation speed n (sec ⁻¹ ) of the left travel motor 30 is inputted from the left motor speed sensor 54 to the left travel inverter control device of the left travel inverter 84 . The detected value of the rotation speed n (sec ⁻¹ ) of the right travel motor 31 is input from the right motor speed sensor 55 to the right travel inverter control device of the right travel inverter 86 . The two left and right motor speed sensors 54 and 55 detect the respective rotational speeds of the two left and right travel motors 30 and 31. The detected value of the rotation speed of each motor speed sensor 54, 55 is output to the control device 40.

Each deck inverter 88 drives a corresponding deck motor 60. Each deck inverter 88 also has a deck inverter circuit and a deck inverter control device that controls the deck inverter circuit, similar to the traveling inverter circuit and traveling inverter control device of each traveling inverter 84, 86.

The operation of each deck inverter 88 is controlled by the control device 40. Thereby, each deck motor 60 is controlled by the control device 40 via the deck inverter 88. Therefore, each mowing blade 18a, 18b, 18c is rotationally driven by a corresponding deck motor 60. Each deck motor 60 is basically driven to maintain a predetermined target rotation speed. The grass cut by the lawnmower 18 is discharged to one side of the vehicle 10 in the left-right direction through a discharge duct 18d provided on one side of the mower deck 19 in the left-right direction.

Furthermore, the detected value of the rotation speed n (sec ⁻¹ ) of the deck motor 60 is input from the deck motor speed sensor 52 to the deck inverter control device of each deck inverter 88 . Each deck motor speed sensor 52 detects the rotation speed of the corresponding deck motor 60. The detected value of the rotation speed of the deck motor speed sensor 52 is output to the control device 40 via the corresponding deck inverter 88. In addition, in FIG. 3, the power supply path from the battery 83 is shown by a thick solid line. Further, in FIG. 3, the signal transmission path is shown by a thin solid line.

The control device 40 includes a calculation section such as a CPU and a storage section such as a memory, and is configured by, for example, a microcomputer. The control device 40 acquires the operation positions of the two operation levers 22 and 23 from the detection signals of the two left and right lever sensors 50 and 51, and controls the left travel motor 30 and the right drive motor according to the operation positions of each operation lever 22 and 23. Each target rotation speed of the travel motor 31 is set.

The control device 40 sets the target rotation speeds of the two left and right travel motors 30 and 31 according to the operation positions of the two left and right operation levers 22 and 23, thereby making it possible to perform both straight travel and turning travel. can.

Furthermore, the vehicle 10 of this example is configured to include a battery monitoring device 90 that monitors the battery status of the battery 82, including at least the battery voltage. For this purpose, the battery monitoring device 90 detects the battery voltage using a voltage sensor. The detected value of the battery voltage is output to the control device 40. The control device 40 presets the upper limit of the target rotation speed of at least one of the travel motors 30 and 31 and the deck motor 60 based on the detection results of the battery state including the detected value of the battery voltage Vb from the battery monitoring device 90. The rotational speed is reduced to the first rotational speed limit, which is the first rotational speed limit. At this time, for example, the control device 40 gradually lowers the upper limit of the target rotation speed of the travel motors 30, 31 by a first predetermined amount or a first predetermined rate for a preset predetermined time. for example linearly. The control device 40 gradually, for example, linearly lowers the upper limit of the target rotation speed of the deck motor 60 by a second predetermined amount or a second predetermined rate in a preset predetermined time. You may let them.

According to the configuration of this example, the load on the battery 82 can be reduced depending on the state of the battery 82. Specifically, the amount of change in the voltage of the battery 82 varies depending on the current output from the battery 82. If the amount of change in the voltage of the battery 82 is large, this means that the current output from the battery 82 is large, so the load on the battery 82 becomes large. Therefore, it is desirable to protect the battery 82 by reducing the load on the battery 82. In the configuration of this example, in order to solve this problem, when the amount of change in the detected value of the battery voltage increases, the upper limit of the target rotation speed of at least one of the travel motors 30, 31 and the deck motor 60 is lowered. As a result, the actual rotation speed decreases, and the load on the battery 82 can be reduced. Further, in order to protect the battery 82, it is not necessary to always lower the upper limit of the power supplied to at least one of the travel motors 30, 31 and the deck motor 60 with a sufficient margin. This makes it possible to both protect the battery 82 and improve work efficiency.

Furthermore, if the amount of change in the voltage of the battery 82 becomes large and the current output from the battery 82 is large, it can be inferred that a large load is being applied to the lawn mower 18 as a working part. In this case, since the deck motor 60 will be overloaded, it is desirable to protect the deck motor 60. In the configuration of this example, when the upper limit of the target rotation speed of the deck motor 60 is lowered when the amount of change in the detected value of the battery voltage increases, the load on the battery 82 can be reduced and the deck motor 60 can be protected. You can also plan.

In FIG. 4 below, a case will be described in which the upper limit value of the target rotation speed of the travel motors 30, 31 is lowered when the amount of change in the voltage of the battery 82 increases. The same applies to the case where the upper limit value of the target rotation speed is lowered.

FIG. 4 shows an example of how the voltage of the battery 82 and the upper limit values of the rotation speeds of the travel motors 30 and 31 change over time in the embodiment. In the example shown in FIG. 4, the control unit 100 controls each traveling motor 30, The upper limit of the target rotation speed of No. 31 is lowered from the reference rotation speed vT0 to the set first limit rotation speed vT1. This makes it possible to both protect the battery 82 and improve work efficiency. In FIG. 4, the thick solid line in the lower diagram shows an example of a change in the actual rotation speed. As shown in FIG. 4, when the rotational speed upper limit value, which is the upper limit of the target rotational speed, decreases from vT0 to the first rotational speed limit vT1, the first rotational speed limit vT1 is lower than the target rotational speed after the rotational speed upper limit value decreases. If it is low, the actual rotational speed also drops to vT1. Thereby, the load on the battery 82 can be reduced by lowering the actual rotational speed, so that it is possible to protect the battery 82 and improve work efficiency at the same time.

FIG. 5 shows an example of how the voltage of the battery 82 and the upper limit values of the rotation speeds of the travel motors 30 and 31 change over time in another example of the embodiment. In the example shown in FIG. 5, the control unit 100 adjusts the upper limit of the target rotation speed of each travel motor 30, 31 according to the magnitude of the amount of change from the reference voltages V1, V2 for each change in battery voltage. Specifically, when the amount of change in battery voltage Vb from reference voltage V1 becomes equal to or greater than first threshold value ΔVbat1 and battery voltage Vb drops to voltage V2, control unit 100 controls the control unit 100 to 4, the upper limit of the target rotation speed of each traveling motor 30, 31 is lowered from the reference rotation speed vT0 to the set first limit rotation speed vT1.

Further, when the battery voltage Vb further decreases from the voltage V2, the control unit 100 sets the target rotation speed of each travel motor 30, 31 according to the amount of change from the voltage V2, using the voltage V2 as a reference voltage. The upper limit is lowered to the set second limit rotation speed vT2. For example, when comparing the voltage change amount △Vbat1 and the voltage change amount △Vbat2, and if △Vbat2 is smaller than △Vbat1, the amount of decrease of the second limit rotation speed vT2 from the first limit rotation speed vT1 is The amount of decrease of the limit rotation speed vT1 from the reference rotation speed vT0 is made smaller, for example, by the ratio of voltage change amount (ΔVbat2/ΔVbat1). On the other hand, when △Vbat2 is larger than △Vbat1, the amount of decrease of the second rotation speed limit vT2 from the first rotation speed limit vT1 is made larger than the amount of decrease of the first rotation speed limit vT1 from the reference rotation speed vT0. . Thereby, the upper limit of the target rotational speed of each traveling motor 30, 31 is adjusted.

Therefore, the target rotation speed of each travel motor 30, 31 can be lowered in stages according to the increase in the load on the battery 82, which improves work efficiency compared to the case where the target rotation speed is greatly reduced all at once. The battery 82 can be protected while suppressing deterioration. In this example, other configurations and operations are the same as those in FIGS. 1 to 4.

In the case of this example as well, in FIG. 5, each deck motor 60 is activated in place of each traveling motor 30, 31, or together with each traveling motor 30, 31, depending on the magnitude of the change in battery voltage from the reference voltage V1. The upper limit of the target rotation speed may be adjusted.

FIG. 6A shows an example of how the voltage of the battery 82, the remaining charge level (SOC) of the battery 82, and the upper limit values of the rotation speeds of the travel motors 30 and 31 change over time in another example of the embodiment. In the configuration of this example, the battery status monitored by the battery monitoring device 90 includes the battery voltage and the remaining charge level (SOC) of the battery 82. The SOC can be expressed as a ratio (%) of the remaining charge amount to the full charge amount of the battery 82.

The control device 40 adjusts the upper limit of the target rotation speed of each travel motor 30, 31 according to the amount of change from the reference voltages V1, V2 for each change in battery voltage and the measured value of the SOC. For this purpose, the battery monitoring device 90 uses, for example, a detection value of a current sensor that detects the input/output current of the battery 82, or a detection value of the current sensor and a detection value of a voltage sensor that detects the voltage of the battery 82. Calculate SOC. The measured SOC value is output to the control device 40.

In the example shown in FIG. 6A, as in the case of FIG. 5, the magnitude of the change in the battery voltage Vb from the reference voltage V1 becomes the first threshold ΔVbat1, and after the battery voltage Vb decreases to the voltage V2, further , has decreased from voltage V2. Further, after the battery voltage Vb decreases by one minute of the first threshold value ΔVbat, the measured SOC of the battery 82 decreases below the SOC threshold value before the battery voltage Vb decreases below the voltage V2.

In this example, when the measured value of SOC is equal to or greater than the SOC threshold value, the control device 40 controls the battery voltage Vb to increase when the amount of change in the battery voltage Vb from the reference voltage V1 becomes equal to or greater than the first threshold value ΔVbat1. When the rotation speed has decreased, the upper limit of the target rotation speed of each traveling motor 30, 31 is lowered to the set first limit rotation speed vT1. On the other hand, when the battery voltage Vb falls below the voltage V2 and the measured value of SOC falls below the SOC threshold, the control device 40 sets the upper limit of the target rotation speed of each traveling motor 30, 31 to the set second limit. Reduce the rotation speed to vT2. At this time, the amount of decrease in the rotational speed limit is changed depending on whether the measured value of SOC is lower than the SOC threshold value. That is, when the SOC measurement value is less than the SOC threshold value, the amount of decrease in the rotational speed limit is made larger than when the SOC measurement value is greater than or equal to the SOC threshold value.

The amount of change in the voltage of the battery 82 changes depending on the SOC. Especially in lithium ion batteries, there is a high correlation between battery voltage and SOC. Therefore, by setting the amount of reduction in the rotational speed limit of each travel motor 30, 31 using the amount of change in the voltage of the battery 82 and the measured value of SOC, it is possible to protect the battery 82 and perform work with higher accuracy. This can be achieved at the same time as improving efficiency. In this example, other configurations and operations are the same as those in FIGS. 1 to 4.

Also in the case of this example, in FIG. 6A, instead of each traveling motor 30, 31, or together with each traveling motor 30, 31, depending on the amount of change in battery voltage from reference voltage V1 and the measured value of SOC, A configuration may also be adopted in which the upper limit of the target rotation speed of each deck motor 60 is adjusted.

Furthermore, in the configuration described using FIG. 6A above, the magnitudes of the first threshold value ΔVbat1 and the threshold value ΔVbat2a may be changed according to the measured value of the SOC. For example, the magnitude of the threshold value when the measured value of SOC is greater than 0 and less than 30% may be different from the magnitude of the threshold value when the measured value of SOC is 30% or more.

Furthermore, in each of the above examples, instead of the amount of decrease of the battery voltage from the reference voltages V1, V2, the rate of change of the battery voltage with respect to the reference voltages V1, V2 is used, The upper limit of one of the target rotational speeds may be lowered. Further, in the configuration described using FIG. 6A, it is determined whether to lower the upper limit of the target rotation speed of at least one of the travel motors 30, 31 and the deck motor 60 using the amount of change in battery voltage and the measured value of SOC. However, the measured value of the maximum discharge current of the battery 82 may be used instead of the measured value of the SOC. At this time, when the measured value of the maximum discharge current becomes a predetermined current value or more, and the amount or rate of change of the battery voltage from the reference voltage V1 becomes a predetermined value or more, the traveling motors 30, 31 and the deck motor 60 The upper limit of at least one of the target rotational speeds may be lowered to a greater extent than when the measured value of the maximum discharge current is less than a predetermined current value. According to this configuration, it is possible to more accurately protect the battery 82 and improve work efficiency.

In each of the above examples, the method shown in FIG. 6B or FIG. 6C, for example, can be considered as a configuration for lowering the upper limit of the target rotation speed of each traveling motor 30, 31. FIG. 6B shows an example of the case where the upper limit rotation speed of the travel motors 30, 31 is lowered in the embodiment, and the relationship between the rotation speed of the travel motors 30, 31 and the indicated positions of the operation levers 22, 23, which are operation units. It is a figure shown by. In the method shown in FIG. 6B, in normal times when the upper limit rotation speed of the travel motor is not lowered, when the operating levers 22 and 23 are at the indicated positions, that is, at the initial position where the operation position instructs to stop the travel motor, the rotation speed of the travel motor is 0%. When it is set to 100% at the position where it is instructed to make the rotation speed as high as possible, the relationship between the indicated position and the rotation speed is in direct proportion over the entire range of the indicated position. As the indicated position approaches 100%, the rotation speed of the travel motor linearly increases. At this time, the upper limit rotation speed of the travel motor is vT0 when the indicated position is 100%. On the other hand, when lowering the upper limit rotation speed of the travel motor, the rotation speed of the travel motor is lower than the upper limit rotation speed vT0 before the change in the range from the predetermined position P1 where the instruction position is lower than 100% to 100%. The rotation speed becomes vT1.

FIG. 6C shows another example of the case where the upper limit rotation speed of the travel motors 30, 31 is lowered in the embodiment. It is a figure shown by. In the method shown in FIG. 6C, the relationship between the designated position and the rotation speed of the travel motor during normal times is the same as that in FIG. 6B. On the other hand, when lowering the upper limit rotation speed of the travel motor, the indicated position is 100% and the upper limit rotation speed vT1 is lower than the upper limit rotation speed vT0 before the change. Further, when the indicated position is other than 100%, as the position approaches 100% from the initial position, the rotational speed increases linearly from 0 toward vT1. In this case, the rotation speed corresponding to the indicated position is lower over the entire range of the indicated position than in normal times.

FIG. 6D is a diagram corresponding to FIG. 4 in another example of the embodiment. In the configuration of this example, each operating lever 22, 23 indicates the target torque of the corresponding travel motor 30, 31 depending on its indicated position. When the amount of change in battery voltage Vb from reference voltage V1 exceeds the first threshold ΔVbat and battery voltage Vb decreases, the control device sets the upper limit of the target torque of each traveling motor 30, 31 to The reference torque tT0 is reduced to the set first limit torque tT1. This makes it possible to both protect the battery 82 and improve work efficiency. In FIG. 6D, an example of the change in actual torque is shown by the thick solid line in the lower diagram. When the torque upper limit value, which is the upper limit of the target torque, decreases from tT0 to the first limit torque tT1 as shown in FIG. also decreases to tT1. Thereby, the load on the battery 82 can be reduced by reducing the actual torque, so that it is possible to protect the battery 82 and improve work efficiency at the same time.

In FIG. 6D, instead of each traveling motor 30, 31, or together with each traveling motor 30, 31, the upper limit of the target torque of each deck motor 60 is It may also be configured to adjust. For example, in each deck motor 60, the target torque changes from the reference torque to the limit torque when the amount of change in the battery voltage Vb from the reference voltage V1 becomes greater than or equal to the first threshold ΔVbat and the battery voltage Vb decreases. It is also possible to adopt a configuration in which the power decreases. In this example, other configurations and operations are the same as those in FIGS. 1 to 4.

In each of the above examples, the upper limit of the motor's target rotation speed or target torque is lowered when the battery voltage change is large. may be controlled.

FIG. 7 is a block diagram showing a vehicle control system 80a according to another example of the embodiment. In the configuration of this example, a maximum discharge current is specified for the battery 82 for driving each traveling motor 30, 31 and each deck motor 60. The specified value of the maximum discharge current is stored in advance in the storage section of the control device 40, or is acquired from the battery monitoring device 90 via the signal line S1, which is a communication means. At this time, the maximum discharge current may be constantly transmitted from the battery monitoring device 90 via CAN communication. Instead of the signal line, the battery monitoring device 90 and the control device 40 may have a wireless communication section as a communication means for mutually transmitting and receiving wireless signals.

The vehicle also includes a first current sensor 61 that detects a discharge current ia output from the battery 82 to the left inverter 84, and a second current sensor 61 that detects a discharge current ib output from the battery 82 to the right inverter 86. 62, and a third current sensor 63 that detects the discharge current IC output from the battery 82 to each deck inverter 88. The first current sensor 61, the second current sensor 62, and the third current sensor 63 constitute a current sensor that measures the actual discharge current of the battery 82.

The detected value of the first current sensor 61 is acquired by the left running inverter control device of the left running inverter 84. The detected value of the second current sensor 62 is acquired by the right running inverter control device of the right running inverter 86. The detected value of the third current sensor 63 is acquired by the deck inverter control device of the deck inverter 88. The control device 40 detects the detected value of the discharge current from the battery 82 to each running inverter 84 , 86 obtained by each running inverter 84 , 86 , and the detected value of the discharge current from the battery 82 to the deck inverter 88 obtained by the deck inverter 88 . The detected value of the discharge current is acquired via the signal lines S2, S3, and S4, and the actual discharge current of the battery 82 is calculated from the sum of each detected value. At this time, the detection value of the discharge current acquired by each inverter 84, 86, 88 may be always transmitted from each inverter 84, 86, 88 by CAN communication. Instead of the signal line, each inverter 84, 86, 88 and the control device 40 have a wireless communication section as a communication means for transmitting and receiving wireless signals between the inverters 84, 86, 88 and the control device 40. May have.

Further, the control device 40 controls the rotational speed of each of the travel motors 30 and 31 while each deck motor 60 is being driven so that the actual discharge current of the battery 82 does not exceed a prescribed maximum discharge current. For example, when the actual discharge current of the battery 82 reaches a threshold current lower than the maximum discharge current, the control device 40 reduces the target rotation speed of each travel motor 30, 31. At this time, for example, the control device 40 adjusts the target rotation speed of the travel motors 30, 31 by a preset first predetermined amount for a preset predetermined time regardless of the operation of the left and right operating levers 22, 23. Alternatively, it is gradually decreased at a first predetermined rate, for example linearly. At this time, if an instruction is given to reduce the speed of the vehicle using the left and right operating levers 22, 23 in order to further improve safety when the vehicle is running, the target rotation speed of the travel motors 30, 31 is determined according to the instruction. It is also possible to adopt a configuration that reduces the .

According to the configuration of this example, by controlling the rotational speed of each traveling motor 30, 31, it is possible to prevent the actual discharge current of battery 82 from exceeding the maximum discharge current while driving each deck motor 60. Therefore, even if a process is performed to cut off the current flowing from the battery 82 to each motor 30, 31, 60 in order to protect the battery 82, the vehicle can be prevented from suddenly stopping.

In addition, when the control unit 100 is configured to obtain the maximum discharge current from the battery monitoring device 90 via the communication means, when the type of battery is changed, the maximum discharge current according to the type of battery is changed. In order to set the current, it is only necessary to change the settings of the battery monitoring device 90, and there is no need to change the settings of the control unit 100.

Furthermore, as shown by the broken line in FIG. 7, the vehicle may be configured to include a battery current sensor 64 that detects the actual discharge current iz output from the battery 82. Then, the battery monitoring device 90 acquires the detected value of the battery current sensor 64, and the control device 40 transmits the detected value of the actual discharge current iz acquired by the battery monitoring device 90 to a signal line serving as a communication means or to a wireless communication unit. The configuration may be such that the information is acquired via the . According to this configuration, in order to obtain the actual discharge current of the battery 82 by the control device 40, the current sensor that detects the discharge current of the battery 82 and the control device 40 transmit the detected value of the actual discharge current of the battery 82. There is no need to connect only with a dedicated signal line.

Furthermore, in the above description, a current sensor is provided separately from each inverter 84 , 86 , 88 to detect the discharge current output from the battery 82 to the inverter 84 , 86 , 88 . , 86, 88 may be included inside the inverter control device.

FIG. 8 shows the discharge current from the battery 82 to the deck inverter 88 (deck motor side discharge current), the discharge current to the travel inverters 84 and 86 (travel motor side discharge current), and the deck motor 60 in another example of the embodiment. An example of the time course of the target rotational speed of the traveling motors 30 and 31 is shown. In FIG. 8, changes in the amount of grass along the vehicle travel route are shown using shading, and the darker the density, the greater the amount of grass at the current vehicle position. In the part showing the amount of grass, the amount of grass is approximately constant in each range indicated by a plurality of arrows, and the larger the number of arrows, the more the amount of grass is.

As shown in FIG. 8, the target rotation speed of the deck motor 60 is constant. Moreover, since the amount of operation of the left and right operating levers 22, 23 toward the front side is constant from time 0 to t1, the target rotation speed of each traveling motor 30, 31 is also constant. When the vehicle is running, the amount of grass gradually increases from time 0 to t1, which increases the load on the deck motor 60 and increases the discharge current on the deck motor side. Then, at time t1, when the actual discharge current of the battery 82 reaches a threshold current id lower than the maximum discharge current imax, the target rotation speed of each traveling motor 30, 31 decreases thereafter. As a result, the load on the deck motor 60 decreases as the vehicle speed decreases, so the discharge current of the deck motor 60 increases more slowly from time t1 to time t2 than before, and after time t2 the deck motor 60 increases. discharge current decreases. Then, the actual discharge current of the battery 82 gradually decreases and reaches the threshold current id at time t3. Therefore, the restriction control on the target rotation speed of each travel motor 30, 31 is released, so that the target rotation speed of each travel motor 30, 31 is set to a target rotation speed corresponding to the operation amount of the left and right operation levers 22, 23. to return to.

Since the actual discharge current of the battery 82 is thus prevented from exceeding the maximum discharge current, the battery 82 can be protected while preventing the vehicle from suddenly stopping. This makes it possible to both protect the battery 82 and improve work efficiency. In this example, other configurations and operations are the same as those in FIGS. 1 to 4. In the configuration of this example, the control device 40 controls, while each deck motor 60 is being driven, a future predicted discharge current calculated from the trend of the detected discharge current in the past or present of the battery 82, which is a predetermined maximum discharge current. The rotational speed of each travel motor 30, 31 may be controlled so as not to exceed the current.

FIG. 9 schematically shows a circuit configuration for supplying power from the battery 82 to the travel motors 30, 31 (or the deck motor 60) in another example of the embodiment. In this example, the battery 82 is configured to include a plurality of battery packs 101, 102, and 103. In this example, the battery 82 includes n battery packs 101, 102, and 103. The plurality of battery packs 101, 102, 103 are electrically connected to the traveling inverters 84, 86 (or deck inverter 88) by being detachably connected to the pack connecting portion 104, respectively. Parallel connection is possible. The following explanation will focus on a configuration in which the battery 82 and the travel motors 30, 31 are connected via the travel inverters 84, 86, but a configuration in which the battery 82 and the deck motor 60 are connected through the deck inverter 88. But it's the same.

The pack connection section 104 is a connector such as a plug, and is removably connected to the connectors of the battery packs 101, 102, and 103. Since such a pack connection part 104 has a well-known structure in a battery connection part of an electrically assisted bicycle, a detailed description thereof will be omitted. The user can easily attach and detach the plurality of battery packs 101, 102, and 103 one by one to the corresponding pack connection portions 104 independently. Each battery pack 101, 102, 103 has a voltage Vbat_1, Vbat_2, . . . Vbat_n, respectively.

The plurality of pack connection parts 104 include a plurality of forward converters D1, D2 that can flow current only in the direction from the corresponding battery packs 101, 102, 103 to the traveling motors 30, 31, which are the loads. . . . One end of each Dn is connected one by one. The forward converters D1, D2...Dn are, for example, diodes. The other ends of the plurality of forward converters D1, D2, . . . , Dn are connected at a connecting portion 105. Travel motors 30 and 31 are connected to the connection portion 105 via travel inverters 84 and 86.

According to the configuration of this example, when outputting power from the plurality of battery packs 101, 102, 103 to the load section, the battery pack 101, 102, 103 with the highest voltage among the plurality of battery packs 101, 102, 103 Current can be output to the load in order from Thereby, there is no need to adjust the voltages of the plurality of battery packs 101, 102, 103 in advance before outputting current from the battery 82 to the load section. Therefore, the battery 82 can be charged without excessively adjusting the voltage or charge amount of the plurality of battery packs 101, 102, 103. Furthermore, the voltage of the battery 82 can be more stabilized.

In FIG. 9, consider the case where, for example, n=3 and the voltages at the time when the plurality of battery packs 101, 102, 103 are connected to the pack connection part 104 are Vbat_1>Vbat_2>Vbat_n. In this case, power is supplied to the load section from the battery pack 101 with the highest voltage before the other battery packs 102 and 103, so that the voltage of the battery pack 101 decreases. Then, when the voltages of the two battery packs 101 and 102 become equal to each other (Vbat_1=Vbat_2), power is supplied from both of the two battery packs 101 and 102 to the load section side. As a result, the voltages of the two battery packs 101 and 102 decrease.

Furthermore, when the voltages of the three battery packs 101, 102, and 103 become equal to each other (Vbat_1=Vbat_2=Vbat_3), power can be supplied to the load section from all three battery packs 101, 102, and 103. Become.

In this example, other configurations and operations are similar to those in FIGS. 1 to 4. Note that the configuration of this example may be combined with the configuration of FIG. 5, the configuration of FIGS. 6A and 6D, or the configuration of FIGS. 7 and 8.

FIG. 10 schematically shows a circuit configuration for supplying power from the battery 82 to the travel motors 30, 31 (or the deck motor 60) in another example of the embodiment. In this example, each of the plurality of pack connection parts 104 to which the battery packs 101, 102, 103 are connected has one end of the first bidirectional converter 110 in parallel with the forward converters D1, D2...Dn. The sides are connected. The other end side of the first bidirectional converter 110 is connected to the travel motors 30 and 31 (or the deck motor 60) via the connection portion 105 and the travel inverters 84 and 86 (or the deck inverter 88).

The first bidirectional converter 110 is a switch SW1, SW2...SWn connected in parallel to the forward converter D1, D2...Dn. The switches SW1, SW2, . . . SWn are semiconductor switches or mechanical switches whose conduction is controlled by a control signal output from the control device 40. Each first bidirectional converter 110 can, by switching, allow current to flow in both the direction of output from the corresponding battery pack 101, 102, 103 and the direction of input to the corresponding battery pack 101, 102, 103. can.

Further, the vehicle includes voltage sensors 112, 113, and 114 that detect voltages of the plurality of battery packs 101, 102, and 103, respectively. Detection signals representing detection values Vbat_1, Vbat_2, and Vbat_3 of voltage sensors 112, 113, and 114 are output to control device 40.

The control device 40 determines whether the voltages of at least two of the plurality of battery packs 101, 102, 103 match based on the detected values of the voltage sensors 112, 113, 114. It will be judged. When the control device 40 determines that the voltages of at least two or more battery packs 101, 102, 103 match, the control device 40 controls the battery packs 101, 102, 103 whose voltages match. Control signals G1, G2, and Gn for switching to enable bidirectional conduction are output to the first bidirectional converter 110. As a result, the first bidirectional converters 110 corresponding to the battery packs 101, 102, and 103 whose voltages match are switched to enable bidirectional conduction.

According to the configuration of this example, by switching the first bidirectional converter 110 so that conduction can occur in both directions, power is supplied from the load section to the battery packs 101, 102, and 103 through power regeneration, etc., and the battery 82 is activated. Can be charged.

Furthermore, when the voltages of at least two or more battery packs 101, 102, 103 match, the first bidirectional converter 110 corresponding to the battery packs 101, 102, 103 with matching voltages becomes capable of bidirectional conduction. Can be switched. Thereby, when it is possible to supply power to the battery packs 101, 102, 103 from the load section side, input/output of power between the battery packs 101, 102, 103 can be prevented. Thereby, the voltage of the battery 82 can be more stabilized.

In FIG. 10, consider the case where, for example, n=3 and the voltages at the time when the plurality of battery packs 101, 102, 103 are connected to the pack connection part 104 are Vbat_1>Vbat_2>Vbat_n. In this case, when the battery pack 101 with the highest voltage is attached to the pack connection part 104, the corresponding first bidirectional converter 110 is switched by the control device 40 so that bidirectional conduction is possible. Then, as power is supplied from the battery pack 101 to the load section side, the voltage of the battery pack 101 decreases.

Next, when the voltages of the two battery packs 101 and 102 become equal to each other (Vbat_1=Vbat_2), both of the first bidirectional converters 110 corresponding to the two battery packs 101 and 102 can conduct bidirectionally. can be switched to At this time, power is supplied from both of the two battery packs 101 and 102 to the load section side. As a result, the voltages of the two battery packs 101 and 102 decrease.

Furthermore, when the voltages of the three battery packs 101, 102, 103 become equal to each other (Vbat_1=Vbat_2=Vbat_3), all of the first bidirectional converters 110 corresponding to the three battery packs 101, 102, 103 is switched to enable bidirectional conduction. At this time, power is supplied to the load section from all three battery packs 101, 102, and 103.

In this example, other configurations and operations are similar to the configurations in FIGS. 1 to 4 or the configuration in FIG. 9. Note that the configuration of this example may be combined with the configuration of FIG. 5, the configuration of FIG. 6A, the configuration of FIG. 6D, or the configuration of FIGS. 7 and 8. By combining the configuration capable of stabilizing the battery voltage with the configuration of FIGS. 1 to 4, the configuration of FIG. 5, the configuration of FIG. 6A, the configuration of FIG. 6D, or the configuration of FIGS. 7 and 8, the battery 82 protection becomes easier.

FIG. 11 schematically shows a circuit configuration for supplying power from the battery 82 to the travel motors 30, 31 (or the deck motor 60) in another example of the embodiment. In this example, instead of omitting the voltage sensor that detects the voltage of each battery pack 101, 102, 103, the vehicle detects current values Ibat_1, Ibat_2, Ibat_3 output from each battery pack 101, 102, 103. Current sensors 115, 116, 117 are provided. Detection signals from current sensors 115, 116, and 117 are output to control device 40.

The control device 40 determines whether the voltages of at least two of the plurality of battery packs 101, 102, 103 match based on the detected values of the current sensors 115, 116, 117. is determined. When the control device 40 determines that the voltages of at least two or more battery packs 101, 102, 103 match, the control device 40 controls the battery packs 101, 102, 103 whose voltages match. A control signal for switching to enable bidirectional conduction is output to the first bidirectional converter 110. As a result, the first bidirectional converters 110 corresponding to the battery packs 101, 102, and 103 whose voltages match are switched to enable bidirectional conduction.

With the configuration of this example, as well as the configuration of FIG. 10, by switching the first bidirectional converter 110 to enable bidirectional conduction, power is supplied to the battery packs 101, 102, 103 from the load side through power regeneration, etc. can be supplied to charge the battery 82. In this example, other configurations and operations are similar to those in FIG. 10.

FIG. 12 schematically shows a circuit configuration for supplying power from the battery 82 to the travel motors 30, 31 (or the deck motor 60) in another example of the embodiment. In this example, in the configuration of FIG. 10, a second bidirectional converter 118 is connected between the pack connection section 104 and the connection section 105 instead of the first bidirectional converter 110.

The second bidirectional converter 118 is constituted by a FET (field effect transistor) having a parasitic diode. Switching of conduction of the second bidirectional converter 118 is controlled by a control signal output from the control device 40. By switching, each second bidirectional converter 118 can cause current to flow in both the direction of output from the corresponding battery pack 101, 102, 103 and the direction of input to the corresponding battery pack 101, 102, 103. can.

In FIG. 12, consider the case where, for example, n=3 and the voltages at the time when the plurality of battery packs 101, 102, 103 are connected to the pack connection part 104 are Vbat_1>Vbat_2>Vbat_n. In this case, when the battery pack 101 with the highest voltage is attached to the pack connection section 104, the corresponding second bidirectional converter 118 is switched by the control device 40 so that bidirectional conduction is possible. Then, as power is supplied from the battery pack 101 to the load section side, the voltage of the battery pack 101 decreases.

Next, when the voltages of the two battery packs 101 and 102 become equal to each other (Vbat_1=Vbat_2), both of the second bidirectional converters 118 corresponding to the two battery packs 101 and 102 can conduct bidirectionally. can be switched to At this time, power is supplied from both of the two battery packs 101 and 102 to the load section side. As a result, the voltages of the two battery packs 101 and 102 decrease.

Furthermore, when the voltages of the three battery packs 101, 102, 103 become equal to each other (Vbat_1=Vbat_2=Vbat_3), all of the second bidirectional converters 118 corresponding to the three battery packs 101, 102, 103 is switched to enable bidirectional conduction. At this time, power is supplied to the load section from all three battery packs 101, 102, and 103.

In this example, other configurations and operations are similar to the configurations in FIGS. 1 to 4, the configuration in FIG. 9, or the configuration in FIG. 10. Note that the configuration of this example may be combined with the configuration of FIG. 5, the configuration of FIG. 6A, the configuration of FIG. 6D, the configuration of FIGS. 7 and 8, or the configuration of FIG. 11.

10 electric work vehicle (vehicle), 12 left wheel, 13 right wheel, 15, 16 caster wheels, 18 lawn mower, 18a to 18c lawn mowing blade, 18d discharge duct, 19 mower deck, 20 main frame, 20a, 20b side plate section, 20c Connection part, 21 Driver's seat, 22, 23 Operation lever, 24 Grip part, 26, 27 Guide panel, 30 Left travel motor, 31 Right travel motor, 32 Operation part, 33 Working part start switch, 35 Start switch, 40 Control device 40, 50 left lever sensor, 51 right lever sensor, 52 deck motor speed sensor, 54 left motor speed sensor, 55 right motor speed sensor, 60 deck motor, 61 first current sensor, 62 second current sensor, 63 third current sensor, 64 battery sensor, 80, 80a control system, 82 battery, 84 left running inverter, 86 right running inverter, 88 deck inverter, 90 battery monitoring device 90, 100 control unit, 101, 102, 103 battery pack, 104 pack connection part, 105 connection part, 110 bidirectional converter, 112, 113, 114 voltage sensor, 115, 116, 117 current sensor, 118 bidirectional converter, 119 FET.

Claims (17)

at least one motor that drives one or both of a traveling section and a working section included in the vehicle;
an operation unit that instructs the rotational speed or operation of the motor;
a control unit that controls the motor according to an operation of the operation unit;
a battery that supplies power to the motor;
The control unit lowers an upper limit of the rotational speed of the motor based on a detection result of a battery state including a voltage of the battery.
Electric work vehicle. The electric work vehicle according to claim 1,
The control unit sets an upper limit of the rotational speed of the motor when an amount of change in the voltage of the battery from a reference voltage or a magnitude of a rate of change with respect to the reference voltage becomes a first threshold value or more. reducing the rotational speed to a first limit rotational speed;
Electric work vehicle. The electric work vehicle according to claim 1,
The control unit adjusts an upper limit of the rotational speed of the motor according to an amount of change from a reference voltage for each change in voltage of the battery, or a magnitude of a rate of change with respect to the reference voltage.
Electric work vehicle. The electric work vehicle according to claim 1,
The battery state includes a remaining charge of the battery,
The control unit adjusts an upper limit of the rotational speed of the motor according to an amount of change from a reference voltage for each change in voltage of the battery, or a rate of change with respect to the reference voltage, and the remaining charge amount.
Electric work vehicle. The electric work vehicle according to any one of claims 1 to 4,
comprising a battery monitoring device that monitors the battery state;
The control unit lowers the upper limit of the target rotational speed of the motor and lowers the upper limit of the actual rotational speed based on the detection result of the battery state from the battery monitoring device.
Electric work vehicle. The electric work vehicle according to any one of claims 1 to 5,
The at least one motor is a travel motor that drives at least one of the travel units and a work motor that drives at least one of the work units.
Electric work vehicle. at least one motor that drives one or both of a traveling section and a working section included in the vehicle;
an operation unit that instructs the torque or operation of the motor;
a control unit that controls the motor according to an operation of the operation unit;
a battery that supplies power to the motor;
The control unit lowers the upper limit of the torque of the motor based on the detection result of the battery state including the voltage of the battery.
Electric work vehicle. a travel motor that drives at least one travel section;
a work motor that drives at least one work part;
a battery that supplies power to the travel motor and the work motor, the battery having a specified maximum discharge current;
A control unit that controls the travel motor and the work motor,
The control unit includes:
controlling the rotational speed of the travel motor so that the discharge current of the battery does not exceed the maximum discharge current while the work motor is being driven;
Electric work vehicle. The electric work vehicle according to claim 8,
comprising a battery monitoring device that monitors the state of the battery,
The control unit acquires the maximum discharge current from the battery monitoring device via a communication means.
Electric work vehicle. The electric work vehicle according to claim 8,
The travel motor is driven by a travel inverter,
the working motor is driven by a working inverter;
The control unit may calculate the discharge current by using a detected value of a discharge current from the battery to the running inverter obtained by the running inverter and a discharge current from the battery to the working inverter obtained by the working inverter. Calculated from the sum of the detected current value,
Electric work vehicle. The electric work vehicle according to claim 8,
comprising a battery monitoring device that monitors the state of the battery,
The control unit acquires the discharge current from the battery monitoring device via a communication means.
Electric work vehicle. The electric work vehicle according to claim 8,
comprising a sensor that measures the discharge current of the battery,
The control unit acquires the discharge current from the sensor via a communication means.
Electric work vehicle. The electric work vehicle according to any one of claims 1, 7, and 8,
The battery allows the plurality of battery packs to be electrically connected in parallel by detachably connecting the plurality of battery packs to the plurality of pack connection parts,
Each of the plurality of pack connections is connected to a forward converter that can flow current only in the direction of output from the corresponding battery pack.
Electric work vehicle. The electric work vehicle according to any one of claims 1, 7, and 8,
The battery allows the plurality of battery packs to be electrically connected in parallel by detachably connecting the plurality of battery packs to the plurality of pack connection parts,
A bidirectional converter is connected to each of the plurality of pack connection parts, which can cause current to flow in both directions of output from the corresponding battery pack and input direction to the corresponding battery pack by switching. be done,
Electric work vehicle. The electric work vehicle according to claim 14,
comprising a voltage sensor that detects the voltage of each of the plurality of battery packs,
Based on the detected value of the voltage sensor, it is determined whether the voltages of at least two or more of the plurality of battery packs match.
Electric work vehicle. The electric work vehicle according to claim 14,
including a current sensor that detects a current value output from each of the plurality of battery packs,
Based on the detected value of the current sensor, it is determined whether the voltages of at least two or more of the plurality of battery packs match.
Electric work vehicle. The electric work vehicle according to claim 15 or 16,
When the voltages of at least two or more of the battery packs match, the bidirectional converter corresponding to the battery pack whose voltages match is switched to enable bidirectional conduction.
Electric work vehicle.

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