Dump truck

Abstract

The purpose of the present invention is to provide an electric dump truck capable of stabilizing a DC voltage generated between a battery serving as a power source for a travel motor and an inverter for driving the travel motor. A dump truck (1) is provided with a battery (2), travel motors (9, 10), inverters (7, 8), a DC / DC converter (3), a smoothing capacitor (5), a battery control device (6), and a vehicle control device (11). The storage battery control device (6) calculates the chargeable / dischargeable power of the storage battery (2) on the basis of the state of charge of the storage battery (2). The vehicle control device (11) acquires an operation signal corresponding to an acceleration / deceleration operation on the travel motors (9, 10), and calculates a torque command value to be output to the inverters (7, 8) on the basis of the acquired operation signal and the chargeable / dischargeable power calculated by the battery control device (6).

Description

Technical Field

[0001] The present invention relates to an electric dump truck powered by a storage battery. Background Art

[0002] For an electric dump truck, it is important to control the power balance of the storage battery in such a way that the power consumption during the power operation of the driving motor and the generated power during regeneration (hereinafter also referred to as "regenerated power") do not exceed the limits of the charge and discharge power of the storage battery. Patent Document 1 is known as the prior art regarding such control.

[0003] Patent Document 1 discloses a vehicle control device mounted on a vehicle having an internal combustion engine, an electric motor, a storage battery, a DC / DC converter, and an inverter. The vehicle control device disclosed in Patent Document 1 limits the generated power or power consumption of the electric motor to below the upper limit value of the output power of the storage battery.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent No. 6350031 Gazette Summary of the Invention

[0007] An electric dump truck has a capacitor for smoothing voltage (hereinafter also referred to as "smoothing capacitor") between a DC / DC converter that steps down or steps up the input / output voltage of a storage battery serving as a power source for a driving motor and an inverter that drives the driving motor. If the regenerated power of the driving motor exceeds the power that can be charged to the storage battery, the DC voltage of the smoothing capacitor will rise excessively (hereinafter also referred to as "overvoltage state"), resulting in damage to components. On the other hand, if the power consumption during the power operation of the driving motor exceeds the power that the storage battery can release, the DC voltage of the smoothing capacitor will drop excessively (hereinafter also referred to as "voltage shortage state"), and the input voltage of the inverter will decrease. If the input voltage of the inverter decreases, the control of the inverter and the driving motor becomes unstable, leading to the stop of the driving system.

[0008] Patent Document 1 only discloses the following technology: in a vehicle having an internal combustion engine, in order to suppress component damage caused by overcurrent, the generated power or power consumption of the electric motor is limited to below the upper limit value of the output power of the storage battery. The technology disclosed in Patent Document 1 does not consider the application to an electric dump truck without an internal combustion engine at all, and there is room for improvement regarding the stabilization of the DC voltage generated in the dump truck.

[0009] In view of the above, an object of the present invention is to provide an electric dump truck capable of stabilizing the DC voltage generated between a storage battery that serves as a power source for a traveling motor and an inverter that drives the traveling motor.

[0010] To solve the above problems, the dump truck of the present invention is an electric dump truck, comprising: a storage battery; a traveling motor powered by the storage battery; an inverter that generates a drive voltage for the traveling motor; a DC / DC converter that steps down or steps up the input / output voltage of the storage battery; a capacitor provided between the DC / DC converter and the inverter; a battery control device that monitors the charge state of the storage battery; and a vehicle control device that outputs a torque command value for the traveling motor to control the drive of the traveling motor. The dump truck is characterized in that the battery control device calculates the charge and discharge power of the storage battery based on the charge state, the vehicle control device obtains an operation signal corresponding to an acceleration or deceleration operation of the traveling motor, and calculates the torque command value output to the inverter based on the obtained operation signal and the charge and discharge power calculated by the battery control device. For the vehicle control device, a maximum power consumption representing the maximum power consumption of the traveling motor during power running and a maximum regenerative power representing the maximum regenerative power generated by the traveling motor during regeneration are preset. The battery control device calculates a dischargeable power representing the power that the storage battery can release and a chargeable power representing the power that can be charged to the storage battery. The vehicle control device is configured to limit the torque command value so that the power consumption of the traveling motor does not exceed the dischargeable power when the dischargeable power is less than the maximum power consumption, and limit the torque command value so that the regenerative power of the traveling motor does not exceed the chargeable power when the chargeable power is less than the maximum regenerative power.

[0011] Advantages of the Invention

[0012] According to the present invention, an electric dump truck capable of stabilizing the DC voltage generated between a storage battery that serves as a power source for a traveling motor and an inverter that drives the traveling motor can be provided. Description of the Drawings

[0013] Figure 1 It is a view showing the appearance of a dump truck.

[0014] Figure 2 It is a view showing the circuit configuration of the dump truck according to Embodiment 1.

[0015] Figure 3 It shows Figure 2A diagram showing the general operation of the vehicle control device shown.

[0016] Figure 4 It shows Figure 2 A diagram showing the arithmetic logic related to the torque command value of the vehicle control device shown.

[0017] Figure 5 It shows Figure 4 A diagram showing the arithmetic logic related to the torque ratio.

[0018] Figure 6 It explains Figure 5 A diagram showing the maximum power consumption and the maximum regenerative power.

[0019] Figure 7 A diagram showing the circuit configuration of the dump truck according to Embodiment 2.

[0020] Figure 8 It shows Figure 7 A diagram showing the arithmetic logic related to the torque ratio of the vehicle control device shown. Detailed implementation

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For components with the same reference numerals in each embodiment, unless otherwise specified, they have the same functions in each embodiment, and their descriptions are omitted.

[0022] [Embodiment 1]

[0023] Using Figures 1 to 6 , the dump truck 1 of Embodiment 1 will be described. Figure 1 A diagram showing the appearance of the dump truck 1.

[0024] The dump truck 1 is an electric dump truck powered by a storage battery 2. The dump truck 1 is, for example, a dump truck (mine dump truck) that transports earth and sand, minerals, etc. excavated in an open-pit mine. The dump truck 1 may also be a dump truck that receives power supply from a trolley wire W connected to a power generation device. The dump truck 1 may also have a power receiving device such as a pantograph 20 connected to the trolley wire W.

[0025] Figure 2 A diagram showing the circuit configuration of the dump truck 1 of Embodiment 1. Figure 3 It shows Figure 2 A diagram showing the general operation of the vehicle control device 11 shown.

[0026] The dump truck 1 has a storage battery 2, a DC / DC converter 3, a smoothing capacitor 5, a battery control device 6, inverters 7, 8, driving motors 9, 10, and a vehicle control device 11.

[0027] The storage battery 2 is the power source for the traveling motors 9 and 10. The storage battery 2 is connected to the inverters 7 and 8 that drive the traveling motors 9 and 10 via the DC circuit 4. The storage battery 2 discharges electricity when the traveling motors 9 and 10 are in power operation and charges electricity when the traveling motors 9 and 10 are in regeneration.

[0028] The DC / DC converter 3 is a power conversion device that steps down or steps up the input / output voltage of the storage battery 2. The DC / DC converter 3 is provided on the DC circuit 4 that connects the storage battery 2 and the inverters 7 and 8. The DC / DC converter 3 steps up the output voltage of the storage battery 2 and outputs it to the DC circuit 4. The DC / DC converter 3 steps down the voltage of the DC circuit 4 and outputs it to the storage battery 2.

[0029] The DC / DC converter 3 operates based on a control command from the vehicle control device 11. For example, the DC / DC converter 3 maintains the voltage of the DC circuit 4 at a fixed value based on the DC voltage command value from the vehicle control device 11. When the traveling motors 9 and 10 are in power operation, the voltage of the DC circuit 4 decreases. Therefore, the DC / DC converter 3 discharges the storage battery 2 to maintain the voltage of the DC circuit 4 at a fixed value. When the traveling motors 9 and 10 are in regeneration, the voltage of the DC circuit 4 increases. Therefore, the DC / DC converter 3 charges the storage battery 2 to maintain the voltage of the DC circuit 4 at a fixed value.

[0030] The smoothing capacitor 5 is provided on the DC circuit 4 between the DC / DC converter 3 and the inverters 7 and 8. The smoothing capacitor 5 smooths the voltage of the DC circuit 4.

[0031] The traveling motors 9 and 10 are traveling motors that rotate the drive wheels of the dump truck 1. The traveling motors 9 and 10 are electric motors powered by the storage battery 2. The traveling motors 9 and 10 are AC motors and are connected to the inverters 7 and 8. The traveling motors 9 and 10 include a left traveling motor 9 that rotates the drive wheels on the left side of the dump truck 1 and a right traveling motor 10 that rotates the drive wheels on the right side of the dump truck 1. The left traveling motor 9 is connected to the left traveling motor inverter 7. The right traveling motor 10 is connected to the right traveling motor inverter 8.

[0032] The inverters 7 and 8 are power conversion devices that generate the voltage for driving the traveling motors 9 and 10. The inverters 7 and 8 are connected to the DC circuit 4 that is connected to the DC / DC converter 3. The inverters 7 and 8 convert the DC voltage of the DC circuit 4 into a three-phase AC voltage and output the converted AC voltage as the drive voltage to the traveling motors 9 and 10. The inverters 7 and 8 convert the three-phase AC voltage output from the traveling motors 9 and 10 into a DC voltage and output it to the DC circuit 4. The inverters 7 and 8 include a left traveling motor inverter 7 that drives the left traveling motor 9 and a right traveling motor inverter 8 that drives the right traveling motor 10.

[0033] The inverters 7 and 8 operate based on control instructions from the vehicle control device 11. For example, the inverters 7 and 8 adjust the output voltage (i.e., the drive voltage) for the traveling motors 9 and 10 based on the torque command value from the vehicle control device 11 so that the traveling motors 9 and 10 rotate with a torque corresponding to the torque command value.

[0034] The battery control device 6 monitors the charge state of the battery 2. Based on the charge state of the battery 2, the battery control device 6 calculates the charge and discharge power of the battery 2. The charge and discharge power of the battery 2 includes the dischargeable power indicating the power that the battery 2 can release and the chargeable power indicating the power that can be charged to the battery 2. The dischargeable power represents the maximum value (unit: kW) of the power that the battery 2 can instantaneously (per unit time) release when the battery 2 discharges. The chargeable power represents the maximum value (unit: kW) of the power that the battery 2 can instantaneously (per unit time) charge when the battery 2 is charged.

[0035] The battery 2 is configured as a normal characteristic such that the upper limit value of the current that can be charged and discharged varies according to the charge rate of the battery 2. If the charge rate is low, the upper limit value of the current that can be discharged decreases, and if the charge rate is high, the upper limit value of the current that can be charged decreases. The battery control device 6 can calculate the dischargeable power by multiplying the dischargeable current corresponding to the charge rate of the battery 2 by the terminal voltage of the battery 2. The battery control device 6 can calculate the chargeable power by multiplying the chargeable current corresponding to the charge rate of the battery 2 by the terminal voltage of the battery 2.

[0036] The battery 2 has a structure formed by connecting a plurality of secondary battery units in parallel, and is configured to be able to operate even if some of the secondary battery units fail. The battery control device 6 can calculate the dischargeable power or chargeable power of the entire battery 2 based on the dischargeable power or chargeable power of each secondary battery unit and the number of units that can operate. The battery control device 6 outputs the calculated dischargeable power or chargeable power of the entire battery 2 to the vehicle control device 11 via the in-vehicle network of the dump truck 1. The battery control device 6 outputs the calculated dischargeable power or chargeable power to the vehicle control device 11 at a fixed cycle.

[0037] The vehicle control device 11 is a control device that comprehensively controls the travel of the dump truck 1. The vehicle control device 11 includes a processor and a memory, and the processor executes a program stored in the memory, thereby realizing the travel function of the dump truck 1.

[0038] The vehicle control device 11 can make the dump truck 1 travel in different travel modes according to the connection state of the pantograph 20 and the overhead wire W. For example, asFigure 3 As shown, the vehicle control device 11 determines whether the pantograph 20 is connected to the overhead line W (step S1). And, when the pantograph 20 is connected to the overhead line W, the vehicle control device 11 makes the dump truck 1 travel in the overhead line driving mode (step S2). On the other hand, when the pantograph 20 is not connected to the overhead line W, the vehicle control device 11 makes the dump truck 1 travel in the battery driving mode (step S3). And, the vehicle control device 11 calculates control commands for the inverters 7, 8, and the DC / DC converter 3, and outputs them to the inverters 7, 8, and the DC / DC converter 3 respectively (step S4).

[0039] The overhead line driving mode is a driving mode in which the traveling motors 9, 10 are driven and the battery 2 is charged using the power supplied from the power generation equipment via the overhead line W. The battery driving mode is a driving mode in which the traveling motors 9, 10 are driven using the power charged in the battery 2. In any driving mode, the vehicle control device 11 acquires an operation signal corresponding to the acceleration / deceleration operation of the traveling motors 9, 10. For example, it acquires an operation signal indicating the operation amount of the operator on the acceleration pedal or the deceleration (brake) pedal of the dump truck 1. And, the vehicle control device 11 calculates the wheel torque as the target value based on the acquired operation signal and the wheel speed, and calculates the torque command value to be applied to the inverters 7, 8. The power generation equipment connected to the overhead line W has sufficient power supply capacity relative to the motor output of the traveling motors 9, 10. On the other hand, the available discharge power and the available charge power of the battery 2 change according to the charge rate or the failure condition of the battery 2. Therefore, it is important for the vehicle control device 11 to calculate the torque command value that can appropriately drive the traveling motors 9, 10 while considering the available discharge power and the available charge power of the battery 2 in the battery driving mode.

[0040] Therefore, the vehicle control device 11 limits the torque command value based on the charge / discharge power calculated by the battery control device 6. That is, the vehicle control device 11 acquires an operation signal corresponding to the acceleration / deceleration operation of the traveling motors 9, 10, and calculates the torque command value to be output to the inverters 7, 8 based on the acquired operation signal and the charge / discharge power of the battery 2 calculated by the battery control device 6.

[0041] Specifically, for the vehicle control device 11, a maximum power consumption value indicating the maximum power consumption of the driving motors 9 and 10 during power running, and a maximum regenerative power value indicating the maximum regenerative power generated by the driving motors 9 and 10 during regeneration are preset. When the dischargeable power calculated by the battery control device 6 is less than the preset maximum power consumption value, the vehicle control device 11 restricts the torque command value so that the power consumption of the driving motors 9 and 10 does not exceed the dischargeable power. When the chargeable power calculated by the battery control device 6 is less than the preset maximum regenerative power value, the vehicle control device 11 restricts the torque command value so that the regenerative power of the driving motors 9 and 10 does not exceed the chargeable power.

[0042] Use Figure 4 And Figure 5 , the method by which the vehicle control device 11 restricts the torque command value will be described in detail. Figure 4 Is a diagram showing Figure 2 The operation logic related to the torque command value of the vehicle control device 11 shown in the figure. Figure 5 Is a diagram showing Figure 4 The operation logic related to the torque ratio shown in the figure.

[0043] The vehicle control device 11 acquires an operation signal corresponding to the acceleration / deceleration operation of the driving motors 9 and 10. The operation signal corresponding to the acceleration / deceleration operation indicates the operation amount of the acceleration / deceleration operation. For example, the operation signal corresponding to the acceleration / deceleration operation is an operation signal indicating the operation amount of the operator on the acceleration pedal or deceleration pedal of the dump truck 1.

[0044] As Figure 4 Shown in the figure, for the vehicle control device 11, a table (hereinafter also referred to as "torque table") indicating the correspondence between the wheel speed of the dump truck 1 or the rotational speed of the driving motors 9 and 10 and the wheel torque of the dump truck 1 is preset. The torque table includes an acceleration torque table used when the dump truck 1 accelerates and a deceleration torque table used when the dump truck 1 decelerates. The vehicle control device 11 uses the torque table to determine the wheel torque corresponding to the wheel speed. The vehicle control device 11 calculates the torque command value by multiplying the determined wheel torque by a ratio (hereinafter also referred to as "torque ratio") corresponding to the operation amount of the acceleration / deceleration operation indicated by the acquired operation signal.

[0045] Specifically, as Figure 4As shown, the vehicle control device 11 multiplies the wheel torque determined using the acceleration torque table by the torque ratio to calculate the acceleration torque command value, and multiplies the wheel torque determined using the deceleration torque table by the torque ratio to calculate the deceleration torque command value. Further, the vehicle control device 11 uses the polarity of the torque ratio (positive: power running, negative: regeneration), the traveling direction of the dump truck 1, the polarity of the wheel speed, etc. as judgment conditions to determine whether to output the acceleration torque command value or the deceleration torque command value. Then, the vehicle control device 11 outputs the command value corresponding to the judgment result as the torque command value to the inverters 7 and 8.

[0046] The torque ratio represents the ratio of the torque command value to the wheel torque determined using the torque table. In the present embodiment, the vehicle control device 11 restricts the torque ratio based on the dischargeable power and the chargeable power calculated by the battery control device 6, thereby restricting the torque command value. That is, the vehicle control device 11 sets the upper limit value of the torque ratio based on the dischargeable power calculated by the battery control device 6 and the maximum consumption power set in advance. The vehicle control device 11 sets the lower limit value of the torque ratio based on the chargeable power calculated by the battery control device 6 and the maximum regeneration power set in advance.

[0047] Specifically, as Figure 5 shown, the vehicle control device 11 calculates the upper limit value of the torque ratio by dividing the dischargeable power calculated by the battery control device 6 by the maximum consumption power set in advance. The vehicle control device 11 calculates the lower limit value of the torque ratio by dividing the chargeable power calculated by the battery control device 6 by the maximum regeneration power set in advance. The vehicle control device 11 sets the calculated upper limit value and lower limit value of the torque ratio.

[0048] For example, when the dump truck 1 is accelerating, consider the following cases: The storage battery 2 is in a healthy state (a state without faults and with a sufficient charge rate), and the available discharge power of the storage battery 2 is 1900 kW. The maximum power consumption of the driving motors 9 and 10 is 1800 kW. In this case, the vehicle control device 11 calculates the upper limit value of the torque ratio as (1900 / 1800)×100 ≈ 105%. Additionally, consider the following case: The storage battery 2 is in a state with a low charge rate, and the available discharge power of the storage battery 2 is 1500 kW. The maximum power consumption of the driving motors 9 and 10 is 1800 kW. In this case, the vehicle control device 11 calculates the upper limit value of the torque ratio as (1500 / 1800)×100 ≈ 83%. Additionally, consider the following case: A secondary battery unit of a part of the storage battery 2 is in a faulty state, and the available discharge power of the storage battery 2 is 1200 kW. The maximum power consumption of the driving motors 9 and 10 is 1800 kW. In this case, the vehicle control device 11 calculates the upper limit value of the torque ratio as (1200 / 1800)×100 ≈ 66%.

[0049] After setting the upper limit value and the lower limit value of the torque ratio, the vehicle control device 11 regards the acceleration signal, which is the operation signal indicating the operation amount of the operator's accelerator pedal, or the deceleration signal, which is the operation signal indicating the operation amount of the operator's deceleration pedal, as information on the torque ratio input, and compares it with the set upper limit value and lower limit value of the torque ratio. The operation amount of the accelerator pedal or the deceleration pedal represents the amount of depression when the accelerator pedal or the deceleration pedal is depressed to the maximum as 100%.

[0050] When the acceleration signal or the deceleration signal is within the range of the set upper limit value and lower limit value of the torque ratio, the vehicle control device 11 uses this acceleration signal or deceleration signal as the torque ratio to be multiplied by the Figure 4 indicated wheel torque. On the other hand, when the acceleration signal or the deceleration signal exceeds the set upper limit value or lower limit value, the vehicle control device 11 uses the exceeded upper limit value or lower limit value of the torque ratio as the torque ratio to be multiplied by the Figure 4 indicated wheel torque. The vehicle control device 11 calculates the torque command value by multiplying the adopted torque ratio by the Figure 4 indicated wheel torque.

[0051] Using Figure 6 , the maximum power consumption and the maximum regenerative power of the driving motors 9 and 10 preset for the vehicle control device 11 are described. Figure 6 It is to describe Figure 5 the shown maximum power consumption and the maximum regenerative power.

[0052] As described above, the maximum power consumption represents the maximum power consumption of the traveling motors 9 and 10 during power running. The maximum regenerative power represents the maximum regenerative power generated by the traveling motors 9 and 10 during regeneration. The maximum power consumption and the maximum regenerative power are parameters that are predetermined according to the specifications of the dump truck 1 represented by the specifications of the traveling motors 9 and 10 (hereinafter also referred to as "vehicle body specifications") and are preset for the vehicle control device 11.

[0053] The torque table representing the correspondence between the wheel speed of the dump truck 1 or the rotational speeds of the traveling motors 9 and 10 and the wheel torque of the dump truck 1 is determined according to the vehicle body specifications. The wheel torque can be converted into the motor torque T (unit: N·m) of the traveling motors 9 and 10 from the wheel diameter and the reduction ratio of the dump truck 1. The motor torque T can be converted into the motor output P (unit: kW) from the conversion formula P = 2πTN / 60 according to the motor speed N (unit: min －1 ). Therefore, the torque table ( Figure 6 upper figure) can be converted into a motor output table ( Figure 6 lower figure) representing the correspondence between the wheel speed of the dump truck 1 or the rotational speeds of the traveling motors 9 and 10 and the motor output of the traveling motors 9 and 10. From this motor output table, the maximum value of the motor output determined by the vehicle body specifications (hereinafter also referred to as "maximum motor output") is obtained. The maximum power consumption can be calculated by adding the efficiency of the traveling motors 9 and 10 and the power conversion efficiency of the inverters 7 and 8 to the maximum motor output. The maximum regenerative power can be calculated by subtracting the power conversion efficiency of the inverters 7 and 8 from the maximum motor output.

[0054] In this way, the maximum power consumption and the maximum regenerative power are predetermined by the vehicle body specifications and are preset for the vehicle control device 11.

[0055] As described above, the dump truck 1 of Embodiment 1 includes a storage battery 2, traveling motors 9 and 10 powered by the storage battery 2, inverters 7 and 8 that generate drive voltages for the traveling motors 9 and 10, a DC / DC converter 3 that steps down or steps up the input / output voltage of the storage battery 2, a smoothing capacitor 5 provided between the DC / DC converter 3 and the inverters 7 and 8, a storage battery control device 6 that monitors the charge state of the storage battery 2, and a vehicle control device 11 that outputs a torque command value for the traveling motors 9 and 10 to the inverters 7 and 8 to control the drive of the traveling motors 9 and 10. The storage battery control device 6 calculates the charge / discharge power of the storage battery 2 based on the charge state of the storage battery 2. The vehicle control device 11 obtains an operation signal corresponding to the acceleration / deceleration operation for the traveling motors 9 and 10, and calculates a torque command value to be output to the inverters 7 and 8 based on the obtained operation signal and the charge / discharge power calculated by the storage battery control device 6.

[0056] Accordingly, the vehicle control device 11 can limit the power consumption and regenerative power of the traveling motors 9 and 10 to below the charge and discharge power of the storage battery 2. Therefore, the vehicle control device 11 can prevent the DC circuit 4 from becoming a voltage shortage state or an overvoltage state. Thus, the dump truck 1 of the first embodiment can stabilize the voltage of the DC circuit 4 and can prevent the stop of the traveling system and the breakage of components.

[0057] Moreover, in the dump truck 1 of the first embodiment, for the vehicle control device 11, the maximum power consumption and the maximum regenerative power of the traveling motors 9 and 10 are preset. The battery control device 6 calculates the available discharge power and the available charge power of the storage battery 2. When the available discharge power is less than the maximum power consumption, the vehicle control device 11 limits the torque command value so that the power consumption of the traveling motors 9 and 10 does not exceed the available discharge power. When the available charge power is less than the maximum regenerative power, the vehicle control device 11 limits the torque command value so that the regenerative power of the traveling motors 9 and 10 does not exceed the available charge power.

[0058] Accordingly, the vehicle control device 11 can reliably limit the power consumption and the regenerative power of the traveling motors 9 and 10 to below the available discharge power and the available charge power of the storage battery 2. Therefore, the vehicle control device 11 can reliably prevent the DC circuit 4 from becoming a voltage shortage state and can reliably prevent the DC circuit 4 from becoming an overvoltage state. Thus, the dump truck 1 of the first embodiment can reliably stabilize the voltage of the DC circuit 4 and can reliably prevent the stop of the traveling system and the breakage of components.

[0059] Moreover, in the dump truck 1 of the first embodiment, a torque table is preset for the vehicle control device 11. The vehicle control device 11 uses the torque table to determine the wheel torque corresponding to the wheel speed. The vehicle control device 11 calculates the torque command value by multiplying the determined wheel torque by a torque ratio corresponding to the operation amount of the acceleration / deceleration operation indicated by the operation signal. The vehicle control device 11 sets the upper limit value of the torque ratio based on the available discharge power of the storage battery 2 and the maximum power consumption of the traveling motors 9 and 10, and sets the lower limit value of the torque ratio based on the available charge power of the storage battery 2 and the maximum regenerative power of the traveling motors 9 and 10, thereby limiting the torque command value.

[0060] Accordingly, without using a special arithmetic logic or algorithm, the vehicle control device 11 can reliably limit the power consumption and regenerative power of the driving motors 9 and 10 to below the discharge possible power and the charge possible power of the storage battery 2. Therefore, the vehicle control device 11 can reliably and easily prevent the voltage shortage state and overvoltage state of the DC circuit 4. As a result, the dump truck 1 of the first embodiment can reliably and easily stabilize the voltage of the DC circuit 4, and can reliably and easily prevent the stoppage of the driving system and the breakage of components.

[0061] [Second Embodiment]

[0062] Use Figure 7 And Figure 8 , the dump truck 1 of the second embodiment will be described. In the dump truck 1 of the second embodiment, the description of the same configuration and operation as those of the first embodiment will be omitted.

[0063] Figure 7 FIG. is a diagram showing the circuit configuration of the dump truck 1 of the second embodiment. Figure 8 Is showing Figure 7 The arithmetic logic related to torque ratio of the vehicle control device 11 shown in FIG.

[0064] As Figure 7 Shown, the dump truck 1 of the second embodiment includes a left resistor 12 and a left chopper 13 connected in parallel with the left driving motor inverter 7, and a right resistor 14 and a right chopper 15 connected in parallel with the right driving motor inverter 8. That is, the left resistor 12 and the left chopper 13 are connected to the DC circuit 4 between the smoothing capacitor 5 and the left driving motor inverter 7. The right resistor 14 and the right chopper 15 are connected to the DC circuit 4 between the smoothing capacitor 5 and the right driving motor inverter 8.

[0065] The vehicle control device 11 of the second embodiment controls the DC / DC converter 3 in such a way that the regenerative power of the driving motors 9 and 10 charges the storage battery 2, and controls the choppers 13 and 15 in such a way that the remainder is consumed in the resistors 12 and 14. The choppers 13 and 15 supply the regenerative power of the driving motors 9 and 10 to the resistors 12 and 14 based on a control command from the vehicle control device 11. The resistors 12 and 14 convert the supplied regenerative power into heat and consume it.

[0066] As Figure 8As shown, for the vehicle control device 11 of Embodiment 2, in addition to the maximum power consumption and the maximum regenerative power, the resistor consumable power indicating the power that the resistors 12 and 14 can consume is also preset in advance. The resistor consumable power is a parameter that is determined in advance according to the specifications of the resistors 12 and 14 and preset for the vehicle control device 11. The resistor consumable power may also correspond to the capacities of the resistors 12 and 14.

[0067] The vehicle control device 11 of Embodiment 2 sets the lower limit value of the torque ratio based on the chargeable power calculated by the battery control device 6, the maximum regenerative power preset in advance, and the resistor consumable power.

[0068] Specifically, when the battery 2 is in a chargeable state, the vehicle control device 11 of Embodiment 2 calculates the lower limit value of the torque ratio by dividing the sum of the chargeable power calculated by the battery control device 6 and the resistor consumable power preset in advance by the maximum regenerative power preset in advance. When the battery 2 is in a non-chargeable state, the vehicle control device 11 of Embodiment 2 calculates the lower limit value of the torque ratio by dividing the resistor consumable power preset in advance by the maximum regenerative power preset in advance. In addition, the state where the battery 2 is non-chargeable means a state where the charge rate of the battery 2 is 100%, or a state where a failure occurs in the battery 2 or the DC / DC converter 3 or the like and charging is impossible.

[0069] For example, when the dump truck 1 decelerates, consider the following cases: The storage battery 2 is in a healthy state (a state without faults and with a low charge rate), and the chargeable power of the storage battery 2 is 1900 kW. The possible power consumption of the resistors 12 and 14 is 1800 kW, and the maximum regenerative power of the traveling motors 9 and 10 is 2900 kW. In this case, the vehicle control device 11 calculates the magnitude of the lower limit value of the torque ratio as {(1900 + 1800) / 2900}×100 ≒ 127%. For example, consider the following case: When the dump truck 1 decelerates, the charge rate of the storage battery 2 is high, the chargeable power of the storage battery 2 is 1000 kW, the possible power consumption of the resistors 12 and 14 is 1800 kW, and the maximum regenerative power of the traveling motors 9 and 10 is 2900 kW. In this case, the vehicle control device 11 calculates the magnitude of the lower limit value of the torque ratio as {(1000 + 1800) / 2900}×100 ≒ 96%. Consider the following case: Due to a fault in the DC / DC converter 3, the storage battery 2 cannot be charged, the chargeable power of the storage battery 2 is 0 kW, the possible power consumption of the resistors 12 and 14 is 1800 kW, and the maximum regenerative power of the traveling motors 9 and 10 is 2900 kW. In this case, the vehicle control device 11 calculates the magnitude of the lower limit value of the torque ratio as {(0 + 1800) / 2900}×100 ≒ 62%. In addition, the vehicle control device 11 multiplies the calculated magnitude of the lower limit value of the torque ratio by -1 and sets the lower limit value of the torque ratio to a negative value.

[0070] In addition, similar to the vehicle control device 11 of the first embodiment, the vehicle control device 11 of the second embodiment calculates the upper limit value of the torque ratio by dividing the dischargeable power calculated by the battery control device 6 by the maximum power consumption set in advance.

[0071] As described above, the dump truck 1 of the second embodiment further includes resistors 12 and 14 that are connected between the smoothing capacitor 5 and the inverters 7 and 8 and consume the regenerative power of the traveling motors 9 and 10. For the vehicle control device 11, the possible resistor power consumption indicating the power that the resistors 12 and 14 can consume is preset. The vehicle control device 11 sets the lower limit value of the torque ratio based on the chargeable power of the storage battery 2, the maximum regenerative power of the traveling motors 9 and 10, and the possible resistor power consumption of the resistors 12 and 14.

[0072] Accordingly, the vehicle control device 11 can limit the power consumption and regenerative power of the traveling motors 9 and 10 to below the discharge possible power and the charge possible power of the storage battery 2, while reducing the reduction ratio of the torque command value that occurs with the reduction of the charge possible power. Therefore, the vehicle control device 11 can reduce the chance that the charge possible power is lower than the maximum value of the regenerative power, and reduce the chance of limiting the torque command value during deceleration. Therefore, the vehicle control device 11 can easily maintain the original regenerative braking performance of the traveling motors 9 and 10, and can suppress the wear of the mechanical brake of the dump truck 1. Thus, the dump truck 1 of the second embodiment can stabilize the voltage of the DC circuit 4, and can suppress the operating cost of the dump truck 1 while preventing the stop of the traveling system and the breakage of components.

[0073] Moreover, in the dump truck 1 of the second embodiment, the vehicle control device 11 calculates the upper limit value of the torque ratio by dividing the discharge possible power of the storage battery 2 by the maximum value of the power consumption of the traveling motors 9 and 10. When the storage battery 2 is in a state where it can be charged, the vehicle control device 11 calculates the lower limit value of the torque ratio by dividing the sum of the charge possible power of the storage battery 2 and the resistor consumption possible power of the resistors 12 and 14 by the maximum value of the regenerative power of the traveling motors 9 and 10. When the storage battery 2 is in a state where it cannot be charged, the vehicle control device 11 calculates the lower limit value of the torque ratio by dividing the resistor consumption possible power by the maximum value of the regenerative power.

[0074] Accordingly, the vehicle control device 11 can limit the power consumption and regenerative power of the traveling motors 9 and 10 to below the discharge possible power and the charge possible power of the storage battery 2, and at the same time, can maintain the regenerative braking performance of the traveling motors 9 and 10 even when the storage battery 2 is in a state where it cannot be charged. Therefore, the vehicle control device 11 can further suppress the wear of the mechanical brake of the dump truck 1. Thus, the dump truck 1 of the second embodiment can stabilize the voltage of the DC circuit 4, and can suppress the operating cost of the dump truck 1 while preventing the stop of the traveling system and the breakage of components.

[0075] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention described in the technical solution. The present invention can add the configuration of one embodiment to the configuration of another embodiment, replace the configuration of one embodiment with the configuration of another embodiment, or delete a part of the configuration of one embodiment.

[0076] Description of Reference Numerals

[0077] 1…Dump truck, 2…Storage battery, 3…DC / DC converter, 5…Smoothing capacitor (capacitor), 6…Battery control device, 7, 8…Inverter, 9, 10…Travel motor, 11…Vehicle control device, 12, 14…Resistor.

Claims

1. A dump truck, which is an electric dump truck, comprising: a storage battery; a traveling motor powered by the storage battery; an inverter that generates a driving voltage of the traveling motor; a DC / DC converter that steps down or steps up the input / output voltage of the storage battery; A capacitor provided between the DC / DC converter and the inverter; a battery control device for monitoring the charge state of the battery; and a vehicle control device that outputs a torque command value for the drive motor to the inverter to control the drive of the drive motor, The dump truck is characterized in that, The battery control device calculates the charge and discharge power of the battery based on the charge state, The vehicle control device obtains an operation signal corresponding to an acceleration / deceleration operation for the drive motor, and calculates the torque command value output to the inverter based on the obtained operation signal and the charge and discharge power calculated by the battery control device, For the vehicle control device, a maximum power consumption representing the maximum power consumption of the drive motor during power operation and a maximum regenerative power representing the maximum regenerative power generated by the drive motor during regeneration are preset, The battery control device calculates a dischargeable power representing the power that the battery can release and a chargeable power representing the power that can be charged to the battery, The vehicle control device is configured to, When the dischargeable power is less than the maximum power consumption, limit the torque command value so that the power consumption of the drive motor does not exceed the dischargeable power, When the chargeable power is less than the maximum regenerative power, limit the torque command value so that the regenerative power of the drive motor does not exceed the chargeable power.

2. The dump truck according to claim 1, characterized in that, For the vehicle control device, a table representing the correspondence between the wheel speed of the dump truck or the rotational speed of the drive motor and the wheel torque of the dump truck is preset, The vehicle control device is configured to, Use the table to determine the wheel torque corresponding to the wheel speed, and multiply the determined wheel torque by a ratio corresponding to the operation amount of the acceleration / deceleration operation indicated by the operation signal, thereby calculating the torque command value, Set an upper limit value of the ratio based on the dischargeable power and the maximum power consumption, and set a lower limit value of the ratio based on the chargeable power and the maximum regenerative power, thereby limiting the torque command value.

3. The dump truck according to claim 2, characterized in that, It further has a resistor connected between the capacitor and the inverter and consuming the regenerative power, For the vehicle control device, a resistor consumable power representing the power that the resistor can consume is preset, The vehicle control device sets the lower limit value of the ratio based on the chargeable power, the maximum regenerative power, and the resistor consumable power.

4. The dump truck according to claim 3, characterized in that, The vehicle control device is configured to, Divide the dischargeable power by the maximum power consumption, thereby calculating the upper limit value of the ratio, When the storage battery is in a state where it can be charged, the lower limit value of the ratio is calculated by dividing the sum of the chargeable power and the power that can be consumed by the resistor by the maximum value of the regenerative power. When the storage battery is in a state where it cannot be charged, the lower limit value of the ratio is calculated by dividing the power that can be consumed by the resistor by the maximum value of the regenerative power.

Images