Dump truck and power supply system

Abstract

The present disclosure provides a dump truck which does not require installation of a power supply device including a trolley wire on a downhill slope and is capable of using regenerative braking even when the state of charge of a power storage device is high. This dump truck 2 comprises a power reception device 21, a power storage device 22, a sensor 23, a travel motor 24, an inverter 25, a DC / DC converter 26, a resistor 27, a chopper circuit 28, and a control device 29. The control device 29 controls the DC / DC converter 26 and the chopper circuit 28 to supply regenerative power to the power storage device 22. In addition, the control device 29 controls, when the state of charge of the power storage device 22 exceeds an upper limit value, the DC / DC converter 26 and the chopper circuit 28 to supply regenerative power to the resistor 27.

Description

[Technical Field]

[0001] The present disclosure relates to a dump truck and a power supply system. [Background technology]

[0002] Electric power systems for mining transport trucks have been known for some time. Patent Document 1 below discloses a power system for supplying power to an electric motor of a mining transport truck that does not have an engine. This conventional power system includes an on-board electric energy storage system, an inverter, and a controller.

[0003] Patent Document 1 describes that the inverter is configured to receive power from the onboard electrical energy storage system and a trolley power supply system and supply power to the electric motor. Patent Document 1 also describes that the controller supplies power to the electric motor only from the onboard electrical energy storage system while the mining haul truck is traveling on substantially flat ground, and supplies power to the electric motor only from the trolley power supply system when the mining haul truck is traveling uphill or downhill. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2015 / 0090554 Summary of the Invention [Problem to be solved by the invention]

[0005] The above-mentioned conventional power system uses a regenerative brake that converts mechanical energy into electrical energy in the wheel motor when braking the mining transport truck and supplies it to the inverter (Patent Document 1, paragraph 0034). However, this conventional power system has room for improvement in terms of how to deal with cases where excessive electrical energy is generated by the regenerative brake or when the electrical energy storage rate is high. For example, this conventional power system does not have a grid resistor that converts the electrical energy (retard energy) generated by the wheel motor into heat (Patent Document 1, Figure 6).

[0006] Therefore, this conventional power system may not be able to use regenerative braking by the wheel motors once the ultracapacitor bank of the onboard electrical energy storage system is fully charged. It is noted that this conventional power system is capable of returning excess retard energy to the power grid via the trolley wire (Patent Document 1, paragraph 0040). However, in loading areas where no trolley wire is installed, it is necessary to use mechanical brakes, which may be subject to wear.

[0007] Furthermore, if most of the excess retard energy generated by the regenerative braking of the wheel motors is to be returned to the power grid via the trolley wire, it would be necessary to install trolley power systems in many locations, for example, on both uphill and downhill slopes. However, at mining and construction sites, the terrain changes constantly due to mining and excavation, making it necessary to remove and reinstall the trolley power systems. Therefore, it is desirable to minimize the installation location of the trolley power systems.

[0008] The present disclosure provides a dump truck and a power supply system that minimizes the installation space for a power supply device, including a trolley wire, and that allows regenerative braking to be used even when the charge rate of a power storage device is high. [Means for solving the problem]

[0009] One aspect of the present disclosure relates to a vehicle including a power receiving device that receives a supply of electric power from an external source, a power storage device that is electrically connected to the power receiving device and is charged by receiving electric power from the power receiving device, a sensor that detects the voltage of the power storage device, first and second traction motors that rotate by receiving electric power from the power receiving device or the power storage device and generate regenerative electric power during braking, first and second inverters that are provided between the first and second traction motors, the power receiving device, and the power storage device, a DC / DC converter that is provided between the first and second inverters and the power storage device, and a power supply that is electrically connected to the first and second traction motors and generates regenerative electric power during braking. The dump truck is characterized by comprising: a resistor that converts the regenerative power generated by the second traction motor into heat; a chopper circuit provided between the resistor and the first and second traction motors; and a control device that estimates the charging rate of the power storage device based on the detection result of the sensor, and when the regenerative power is generated by the first and second traction motors, controls the DC / DC converter and the chopper circuit to supply the regenerative power to the power storage device, and when the charging rate is higher than a predetermined upper limit, controls the DC / DC converter and the chopper circuit to supply the regenerative power to the resistor. [Effects of the Invention]

[0010] According to the above-described aspect of the present disclosure, it is possible to provide a dump truck and a power supply system that can use regenerative braking even when the charge rate of the power storage device is high, for example, without installing a power supply device including a trolley wire on a downhill slope. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating an embodiment of a power supply system according to the present disclosure. [Figure 2] 1 is a schematic diagram illustrating an embodiment of a power supply system according to the present disclosure. [Figure 3] 1 is a schematic diagram illustrating an embodiment of a power supply system according to the present disclosure. [Figure 4]1 is a schematic diagram illustrating an embodiment of a power supply system according to the present disclosure. [Figure 5] 1 is a schematic diagram illustrating an embodiment of a power supply system according to the present disclosure. [Figure 6] 1 is a schematic diagram illustrating an embodiment of a power supply system according to the present disclosure. [Figure 7] 1 is a schematic diagram illustrating an embodiment of a power supply system according to the present disclosure. [Figure 8] FIG. 7 is a perspective view of a mining site showing an example of the installation location of the power supply system of FIGS. 1 to 6. [Figure 9] 1 is a perspective view showing an embodiment of a dump truck according to the present disclosure. FIG. [Figure 10] 10 is a schematic circuit diagram of the dump truck of FIG. [Figure 11] FIG. 11 is a circuit diagram showing a state when power is supplied to the pantograph of the dump truck of FIG. 10. [Figure 12] FIG. 11 is a circuit diagram showing a state when power is supplied to the pantograph of the dump truck of FIG. 10. [Figure 13] FIG. 11 is a circuit diagram showing a state when power is being supplied from the power storage device of the dump truck of FIG. 10. [Figure 14] FIG. 11 is a circuit diagram showing a state when regenerative braking of the dump truck of FIG. 10 is activated. [Figure 15] FIG. 11 is a circuit diagram showing a state when regenerative braking of the dump truck of FIG. 10 is activated. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of a dump truck and a power supply system according to the present disclosure will be described with reference to the drawings. In the following embodiments, the configuration of the power supply system will be described in detail first, and then the configuration of the dump truck will be described in detail.

[0013] (Power supply system) 1 to 7 are schematic diagrams showing an embodiment of a power supply system according to the present disclosure. The power supply system 1 of this embodiment includes a dump truck 2 of this embodiment and a power supply device 3 that supplies power to a power receiving device 21 of the dump truck 2. Fig. 8 is a perspective view of a mining site MS showing an example of an installation location of the power supply device 3 of Figs. 1 to 6.

[0014] The power supply system 1 of this embodiment can be installed at a site where the topography changes from moment to moment due to excavation, such as a mining site MS or a construction site shown in Fig. 8. The power supply system 1 includes, for example, a plurality of dump trucks 2 and a plurality of power supply devices 3. The power supply devices 3 include, for example, at least one of a trolley wire 31 (see Fig. 1, etc.), a stationary charging overhead line 32 (see Fig. 2), a high-voltage charging station 33 (see Figs. 4 and 5), a low-voltage charging station 34 (see Figs. 4 and 6), and a mobile charging vehicle 35 (see Figs. 4 and 7).

[0015] 1 to 4, the mine site MS includes, for example, a loading area M1 where a load such as minerals is loaded onto a dump truck 2 by a work machine such as a hydraulic excavator HS, an unloading area M2 where the dump truck 2 unloads the load, and a predetermined travel route M3 for the dump truck 2. In addition, for example, as shown in FIG. 4, the mine site MS includes a workshop M4 for performing maintenance on the dump truck 2, a parking lot M5 where operators of the dump truck 2 are changed over, and a vehicle assembly site M6 where the dump truck 2 is assembled.

[0016] The loading area M1 is, for example, an area where the hydraulic excavator HS excavates minerals and earth and is located at a lower position than the unloading area M2. The unloading area M2 is, for example, an area where the cargo loaded onto the body of the dump truck 2 at the loading area M1 is dropped off, and includes a collection site for minerals and earth, a crushing facility, a dump site, etc.

[0017] The travel route M3 is a predetermined travel path for the dump truck 2, for example, between a loading area M1 and an unloading area M2, or between the loading area M1 or the unloading area M2 and a workshop M4, an aircraft parking area M5, or a vehicle body assembly site M6. The travel route M3 includes an uphill slope M31, a flat section M32 (see FIG. 3), and a downhill slope M33. The uphill slope M31, the flat section M32, and the downhill slope M33 can be distinguished, for example, by their gradients. The gradients of the uphill slope M31 and the downhill slope M33 are, for example, 1% or more, and the gradient of the flat section M32 is, for example, less than 1%.

[0018] The trolley wire 31 of the power supply device 3 is installed on a predetermined travel route M3 of the mine site MS, for example, as shown by a dashed line in Fig. 8. In this embodiment, for example, as shown in Figs. 1, 3, and 4, the trolley wire 31 is installed only on an uphill slope M31 included in the predetermined travel route M3 of the dump truck 2, and is not installed on a flat section M32 or a downhill slope M33. Power is supplied to the trolley wire 31 via a main station M7 and a substation M8 of the mine site MS, for example, as shown in Fig. 3.

[0019] The main station M7, for example, steps down high-voltage AC power of 20 kV to 30 kV supplied from a power plant via a transmission line to AC power of about 6 kV to 7.2 kV and supplies it to the substation M8 via a power transmission cable. The substation M8, for example, converts the AC power supplied from the main station M7 into DC power of about 2000 V to 2600 V and supplies it to the trolley wire 31. The trolley wire 31 supplies power to a pantograph 211 (see FIGS. 9 and 10) of the power receiving device 21 of the dump truck 2, which will be described later.

[0020] In this embodiment, for example, as shown in FIGS. 2 and 8 , the stationary charging overhead line 32 of the power supply device 3 is installed in a power supply area M9 that is off the predetermined travel route M3 of the dump truck 2. The stationary charging overhead line 32 is supplied with power via a main station M7 and a substation M8, for example, similar to the trolley wire 31. The stationary charging overhead line 32 supplies power to a pantograph 211 of the dump truck 2, for example, similar to the trolley wire 31. The length of the stationary charging overhead line 32 is, for example, the length of one to several dump trucks 2, and is shorter than the length of a normal trolley wire 31. The stationary charging overhead line 32 can be installed in the power supply area M9 that is adjacent to a workshop M4 and a parking area M5, for example.

[0021] In this embodiment, for example, the high-voltage charging station 33 is installed in a power supply area M9 that is off the predetermined travel route M3 of the dump truck 2, similar to the stationary charging overhead line 32. The high-voltage charging station 33 is supplied with power via a main station M7 and a substation M8, similar to the trolley wire 31 and the stationary charging overhead line 32. As shown in FIG. 5 , a first charging port 212 included in the power receiving device 21 of the dump truck 2 is connected to a power supply unit 331 of the high-voltage charging station 33. The high-voltage charging station 33 supplies power to the first charging port 212 of the dump truck 2 that is connected to the power supply unit 331.

[0022] In this embodiment, for example, the low-voltage charging station 34 is installed in a power supply area M9 that is off the predetermined travel route M3 of the dump truck 2, similar to the stationary charging overhead line 32 and the high-voltage charging station 33. The low-voltage charging station 34 is supplied with DC power via, for example, a main station M7 and a substation M8. The low-voltage charging station 34 reduces the voltage of the supplied DC power from 400 V to approximately 1500 V, and supplies the power to a second charging port 213 included in the power receiving device 21 of the dump truck 2 via a charging cable 341, as shown in FIG. 6 .

[0023] 7, in this embodiment, the mobile charging vehicle 35 is a self-propelled vehicle equipped with a plurality of secondary batteries. The mobile charging vehicle 35, for example, drives to the vicinity of the dump truck 2 that needs to be charged and stops there, and supplies the power stored in the plurality of secondary batteries to the second charging port 213 of the dump truck 2 via a charging cable 351, similar to the low-voltage charging station 34.

[0024] In this embodiment, a case will be described in which the mobile charging vehicle 35 has a secondary battery charged with power for supplying to an external device such as a dump truck 2. However, the mobile charging vehicle 35 may also have, for example, a power generation device that generates power using an engine. In this case, the mobile charging vehicle 35 does not need to have all of the power for supplying to the external device charged in the secondary battery. Also, for example, the mobile charging vehicle 35 does not need to have a secondary battery as long as it has a configuration that allows the generated power to be supplied to the external device from the power generation device without going through a secondary battery.

[0025] (Dump truck) Next, the configuration of the dump truck 2 of this embodiment will be described in detail. Fig. 9 is a perspective view showing an embodiment of the dump truck according to the present disclosure. Fig. 10 is a schematic circuit diagram of the dump truck 2 of Fig. 9.

[0026] The dump truck 2 of this embodiment includes a power receiving device 21, a power storage device 22, a sensor 23, a traveling motor 24, an inverter 25, a DC / DC converter 26, a resistor 27, a chopper circuit 28, and a control device 29. In the example shown in Fig. 10, the dump truck 2 also includes a switch box SB and an auxiliary power device PD. The configuration of each part of the dump truck 2 of this embodiment will be described in detail below.

[0027] The power receiving device 21 is a device that receives a supply of electric power from outside the dump truck 2. The power receiving device 21 includes at least one of a pantograph 211, a first charging port 212, and a second charging port 213, for example.

[0028] As shown in Fig. 9 , the pantograph 211 is provided on the upper part of the dump truck 2, and is configured to be extendable and retractable up and down by, for example, an operation by an operator of the dump truck 2. By extending upward, the pantograph 211 comes into contact with the trolley wire 31 or the stationary charging overhead line 32 of the power supply device 3, and receives a supply of power from the trolley wire 31 or the stationary charging overhead line 32. By contracting downward, the pantograph 211 separates from the trolley wire 31 or the stationary charging overhead line 32, and stops the supply of power from the trolley wire 31 or the stationary charging overhead line 32. As shown in Fig. 10 , the pantograph 211 is connected, for example, to the traction motor 24 via an inverter 25, and to the power storage device 22 via a DC / DC converter 26.

[0029] 5, the first charging port 212 is provided on the upper part of the dump truck 2 and is configured to extend and retract up and down by operation of the operator of the dump truck 2, similar to the pantograph 211, for example. When the first charging port 212 extends upward, it comes into contact with the power feeding unit 331 of the high-voltage charging station 33 of the power feeding device 3, and receives a supply of power from the high-voltage charging station 33. When the first charging port 212 contracts downward, it moves away from the power feeding unit 331 of the high-voltage charging station 33, and the supply of power from the high-voltage charging station 33 stops.

[0030] Furthermore, the first charging port 212 may be configured to automatically extend and come into contact with a power supply unit 331 of the high-voltage charging station 33, for example, when the dump truck 2 is stopped at a predetermined position relative to the high-voltage charging station 33. As shown in FIG. 10 , the first charging port 212 is connected to a positive terminal 221 and a negative terminal 222 of the power storage device 22 via a DC / DC converter 26, for example.

[0031] 6 and 7, the second charging port 213 is provided, for example, at a lower position on the front, side, or rear of the dump truck 2. The second charging port 213 can be connected to a charging cable 341 of a low-voltage charging station 34 or a charging cable 351 of a mobile charging vehicle 35. As shown in FIG. 10, the second charging port 213 is directly connected to the positive terminal 221 and the negative terminal 222 of the power storage device 22.

[0032] The electrical configuration related to the traveling drive of the dump truck 2 will be described below with reference to Fig. 10. The power storage device 22 is electrically connected to the power receiving device 21, and is charged by receiving power from the power receiving device 21. The power storage device 22 is also electrically connected to the travel motor 24, and is charged by receiving regenerative power generated by regenerative braking of the travel motor 24. The power storage device 22 includes, for example, a plurality of unit cells 223 connected in series and in parallel. The type of unit cells 223 is not particularly limited, and it is possible to use, for example, a lead battery or a lithium-ion secondary battery.

[0033] Sensor 23 is used to estimate the charging rate of power storage device 22. Sensor 23 detects the voltage of power storage device 22 when power is stored therein, the voltage received by power receiving device 21, and the voltage regenerated by traction motor 24. Sensor 23 includes, for example, a voltage sensor 231 that detects the voltage of the power supply path between power receiving device 21 and DC / DC converter 26. Voltage sensor 231 is a sensor that can detect, for example, the power receiving voltage of power receiving device 21 and the regenerated voltage of traction motor 24, the voltage of the power receiving voltage and the regenerated voltage that is supplied to power storage device 22 and the voltage that is supplied to resistor 27 (described later), and the voltage stored in power storage device 22 when power that can be charged to power storage device 22 is being generated by power receiving device 21 or traction motor 24 (i.e., when power receiving device 21 is connected to power supply device 3 or traction motor 24 is receiving regenerative braking). More specifically, sensor 23 includes a voltage sensor 231 that detects the voltage of the power supply path between pantograph 211 or first charging port 212 and DC / DC converter 26. Sensor 23 also includes a voltage sensor 232 that detects the voltage between positive terminal 221 and negative terminal 222 of power storage device 22, for example, to more directly detect the voltage of power storage device 22.

[0034] The travel motor 24 is driven by power supplied from the power receiving device 21 or the power storage device 22. More specifically, in this embodiment, the dump truck 2 has a rear-wheel drive drive system in which, of the front and rear wheels, the rear wheels, which are the left and right wheels on the rear side, are drive wheels, and the front wheels, which are the left and right wheels on the front side, are driven wheels. The travel motor 24 has a right travel motor (first travel motor) 241 that drives the right rear wheel, and a left travel motor (second travel motor) 242 that drives the left rear wheel.

[0035] The traveling motor 24 is supplied with power from the pantograph 211 or the power storage device 22 and driven to perform rotational motion. In this embodiment, the right rear wheel (right rear tire) rotates when the right traveling motor 241 rotates, and the left rear wheel (left rear tire) rotates when the left traveling motor 242 rotates. In this way, the traveling motor 24 is driven, causing the wheels of the dump truck 2 to rotate and causing the dump truck 2 to travel.

[0036] Furthermore, each of the right traveling motor 241 and the left traveling motor 242 of the traveling motor 24 is rotated by the wheels when braking the dump truck 2 to generate electricity and is used for regenerative braking that converts the kinetic energy of the dump truck 2 into electrical energy. Here, the power generated by using the traveling motor 24 for regenerative braking is called regenerative power. In other words, the traveling motor 24 is configured to rotate by receiving power from the power receiving device 21 or the power storage device 22 and to generate regenerative power by being braked during rotation.

[0037] The inverters 25 (first and second inverters 251 and 252) are provided between the travel motors 24 (right travel motor 241 and left travel motor 242), the power receiving device 21, and the power storage device 22. For example, the inverter 25 includes a right inverter (first inverter) 251 provided between the right travel motor (first travel motor) 241, the power receiving device 21, and the power storage device 22, and a left inverter (second inverter) 252 provided between the left travel motor (second travel motor) 242, the power receiving device 21, and the power storage device 22. In this embodiment, the right inverter 251 is provided between the right travel motor 241 and the power receiving device 21, and the left inverter 252 is provided between the left travel motor 242 and the power storage device 22. The inverter 25 is controlled by, for example, the control device 29, and converts DC power supplied from the power supply device 3 or the power storage device 22 into AC power and supplies it to the traction motor 24, and also converts regenerative power generated by the traction motor 24 into DC power and supplies it to the power storage device 22 or the resistor 27.

[0038] DC / DC converter 26 is provided in a power supply path between right and left inverters (first and second inverters) 251 and 252 of inverter 25 and power storage device 22. For example, in this embodiment, DC / DC converter 26 is provided between left inverter (second inverter) 252 and power storage device 22. DC / DC converter 26 is controlled by, for example, control device 29, and reduces regenerative power supplied from traction motor 24 via inverter 25 to a predetermined voltage and supplies the power to power storage device 22. DC / DC converter 26 is also provided in a power supply path between pantograph 211 and first charging port 212 of power receiving device 21 and power storage device 22. DC / DC converter 26 is controlled by, for example, control device 29, and reduces DC power supplied from pantograph 211 or first charging port 212 of power receiving device 21 to a predetermined voltage and supplies the power to power storage device 22.

[0039] Resistor 27 is electrically connected to right and left travel motors (first and second travel motors) 241 and 242 of travel motor 24, and converts regenerative power generated by regenerative braking of travel motor 24 into heat. More specifically, resistor 27 converts regenerative power supplied from travel motor 24 via inverter 25 and chopper circuit 28 into heat and dissipates it into the atmosphere. Resistor 27 is mounted on a grid box of dump truck 2, for example.

[0040] Chopper circuit 28 is provided between resistor 27 and right and left travel motors (first and second travel motors) 241 and 242 of travel motor 24. More specifically, a right inverter 251 is provided between chopper circuit 28 and right travel motor 241, and chopper circuit 28 is provided between right inverter 251 and resistor 27. Furthermore, a left inverter 252 is provided between chopper circuit 28 and left travel motor 242, and chopper circuit 28 is provided between left inverter 252 and resistor 27. Chopper circuit 28 is controlled by control device 29, for example, to control the amount of regenerative power supplied to resistor 27.

[0041] The control device 29 is configured by, for example, one or more microcontrollers equipped with a central processing unit (CPU), memory, a timer, an input / output unit, etc. The control device 29 is connected to the sensor 23 via, for example, a signal line, and receives detection results from the sensor 23. In the example shown in FIG. 10, the dump truck 2 is equipped with two control devices 29, but the dump truck 2 may be equipped with one or a plurality of control devices 29, three or more.

[0042] Control device 29, for example, causes a CPU to execute a program stored in memory, thereby estimating the state of charge of power storage device 22 based on the detection result of sensor 23, and controls inverter 25, DC / DC converter 26, chopper circuit 28, and switch box SB. More specifically, when the state of charge of power storage device 22 estimated based on the detection result of sensor 23 is below a predetermined lower limit, control device 29 controls DC / DC converter 26 and chopper circuit 28 to supply regenerative power of traction motor 24 to power storage device 22.

[0043] Furthermore, when the charging rate of power storage device 22 is higher than a predetermined upper limit, control device 29 controls DC / DC converter 26 and chopper circuit 28 to supply regenerative power from traction motor 24 to resistor 27. The upper and lower limits of the charging rate of power storage device 22 are set in advance in control device 29 to have a predetermined range, for example, between 60% and 80%, or between 70% and 90%, etc.

[0044] The lower limit value, which is a threshold value of the charging rate for determining whether or not the power received by the above-mentioned power receiving device 21 or the regenerative power of the driving motor 24 should be supplied to the power storage device 22, and the upper limit value, which is a charging rate for determining whether or not the power should be supplied to the resistor 27, are set, for example, from the viewpoint of protecting the power storage device 22.

[0045] The lower limit value does not have to be set, and may be set to the same value as the upper limit value, for example. That is, for example, if the traction motor 24 generates electric power that can be supplied (charged) to the power storage device 22, the regenerative electric power may be supplied to the power storage device 22 and charging of the power storage device may be started as long as the charging rate has not reached the upper limit value.

[0046] The switch box SB includes, for example, a first switch box SB1 provided in the power supply path between the pantograph 211 of the power receiving device 21 and the right inverter 251 of the inverter 25, and a second switch box SB2 provided in the power supply path between the left inverter 252 of the inverter 25 and the DC / DC converter 26. The switch box SB is always turned on, for example, when the dump truck 2 is started up and during normal operation, and is turned off by the control device 29 when the dump truck 2 is at rest or in predetermined cases, thereby interrupting the power supply path.

[0047] The auxiliary power device PD is connected to the pantograph 211 and the inverter 25 via, for example, a switch box SB. In this embodiment, the auxiliary power device PD is provided between the second switch box SB2 and the DC / DC converter 26. The auxiliary power device PD supplies electric power to, for example, an air conditioning power supply, a power supply for a power device, a cooling system power supply, a hydraulic system power supply, a vehicle body control power supply, and a lighting power supply of the dump truck 2.

[0048] Hereinafter, the flow of current in several states of the dump truck 2 of this embodiment will be described with reference to Fig. 11 to Fig. 15. Note that in Fig. 11 to Fig. 15, for clarity of the drawings, the flow of current (positive side) from the power supply source toward the power consumption destination (supply destination) in each state is schematically shown as a hollow arrow, and the flow of current (negative side) from the consumption destination (supply destination) toward the power supply source is schematically shown as a solid black arrow.

[0049] 11 is a circuit diagram that is superimposed on the circuit diagram of FIG. 10 to show a schematic electrical state when the dump truck 2 receives power from the trolley wire 31 via the pantograph 211 and operates. For example, when the dump truck 2 traveling through a mining site MS approaches an uphill slope M31 on the travel route M3, the operator of the dump truck 2 extends the pantograph 211 to bring it into contact with the trolley wire 31 of the power supply device 3 that is installed only on the uphill slope M31. As a result, power is supplied to the dump truck 2 from the trolley wire 31 via the pantograph 211 of the power receiving device 21, and current flows from the pantograph 211 to the pair of travel motors 24 via the pair of inverters 25, driving the travel motors 24 and causing the dump truck 2 to travel.

[0050] Here, when the charging rate of power storage device 22 estimated based on the detection result of sensor 23 is below a predetermined lower limit, or when power receiving device 21 is receiving power and the charging rate is below an upper limit of the active charging rate, control device 29 controls DC / DC converter 26 and chopper circuit 28 to supply the power supplied to pantograph 211 to power storage device 22, as shown in Fig. 11. As a result, a current flows from pantograph 211 to power storage device 22 via DC / DC converter 26, and power storage device 22 is charged. Furthermore, a current flows from pantograph 211 to auxiliary power device PD via two switch boxes SB, and power is supplied to auxiliary power device PD.

[0051] Fig. 12 is a circuit diagram that is superimposed on the circuit diagram of Fig. 10 and that schematically shows another electrical state when the dump truck 2 operates receiving power from the trolley wire 31 via the pantograph 211. When the charging rate of the power storage device 22 estimated based on the detection result of the sensor 23 exceeds a predetermined upper limit value, the control device 29 turns off the switch box SB adjacent to the DC / DC converter 26, for example.

[0052] 12, the power supply path between the pantograph 211 and the power storage device 22 is interrupted, the current from the pantograph 211 to the power storage device 22 is stopped, and charging of the power storage device 22 is stopped. In addition, a current flows from the power storage device 22 to the auxiliary power device PD via the DC / DC converter 26, and power is supplied from the power storage device 22 to the auxiliary power device PD.

[0053] Fig. 13 is a circuit diagram that is superimposed on the circuit diagram of Fig. 10 and that schematically shows the electrical state when the dump truck 2 operates using the power stored in the power storage device 22. For example, when the dump truck 2 travels through a mining site MS, the operator of the dump truck 2 retracts the pantograph 211 to separate it from the trolley wire 31 of the power supply device 3 when the dump truck 2 reaches the top of the uphill slope M31 on the travel route M3 and approaches the flat area M32 or the unloading area M2. This stops the power supply from the trolley wire 31 to the dump truck 2 via the pantograph 211.

[0054] Then, the control device 29 controls, for example, the pair of inverters 25, the DC / DC converter 26, the switch box SB, and the chopper circuit 28 to supply power from the power storage device 22 to the traveling motor 24. As a result, a current flows from the power storage device 22 to the pair of traveling motors 24, driving the pair of traveling motors 24 to travel the dump truck 2. In addition, a current flows from the power storage device 22 to the auxiliary power device PD, and power is supplied from the power storage device 22 to the auxiliary power device PD.

[0055] Fig. 14 is a circuit diagram that is superimposed on the circuit diagram of Fig. 10 to show a schematic electrical state when the dump truck 2 operates using electric power obtained by regenerative braking. For example, an operator of the dump truck 2 traveling through a mining site MS activates regenerative braking by the pair of travel motors 24 when braking the dump truck 2. More specifically, for example, when the dump truck 2 approaches a downhill slope M33 from an uphill slope M31, a flat area M32, a loading area M1, or an unloading area M2, the operator activates regenerative braking by the pair of travel motors 24. As a result, the kinetic energy of the dump truck 2 is converted into electric energy by the pair of travel motors 24, braking the dump truck 2, and regenerative electric power is generated by the travel motors 24.

[0056] Here, when the charging rate of power storage device 22 estimated based on the detection result of sensor 23 is below a predetermined lower limit, or when regenerative power is generated by traction motor 24 and is below the upper limit of the active charge rate, control device 29 controls DC / DC converter 26 and chopper circuit 28 to supply regenerative power generated by traction motor 24 to power storage device 22. As a result, current flows from the pair of traction motors 24 to power storage device 22, charging power storage device 22. In addition, current flows from the pair of traction motors 24 to auxiliary power devices PD, and regenerative power is supplied from the pair of traction motors 24 to auxiliary power devices PD.

[0057] Fig. 15 is a circuit diagram that is superimposed on the circuit diagram of Fig. 10 and that schematically shows another electrical state when the dump truck 2 operates using electric power obtained by regenerative braking. When the state of charge of the power storage device 22 estimated based on the detection result of the sensor 23 exceeds a predetermined upper limit, the control device 29 controls the DC / DC converter 26 and the chopper circuit 28 to supply the regenerative electric power generated by the traveling motor 24 to the resistor 27. As a result, a current flows from the pair of traveling motors 24 to the resistor 27 via the pair of inverters 25 and the chopper circuit 28, and the regenerative electric power generated by the pair of traveling motors 24 is converted into thermal energy and dissipated (consumed) into the atmosphere.

[0058] Furthermore, the control device 29 turns off the switch box SB, for example, to interrupt the power supply path between the pair of traction motors 24 and the power storage device 22. This stops the current from the pair of traction motors 24 to the power storage device 22, and stops charging of the power storage device 22. Furthermore, a current flows from the power storage device 22 to the auxiliary power device PD via the DC / DC converter 26, and power is supplied from the power storage device 22 to the auxiliary power device PD.

[0059] As described above, the dump truck 2 of this embodiment includes the power receiving device 21 that receives a supply of electric power from an external source, the power storage device 22 that is charged by receiving electric power from the power receiving device 21, and the sensor 23 that detects the voltage of the power storage device 22. The dump truck 2 also includes the travel motors 24 (first and second travel motors 241 and 242) that are driven by receiving electric power from the power receiving device 21 or the power storage device 22, the inverters 25 (first and second inverters 251 and 252) that are provided between the travel motors 24 (first and second travel motors 241 and 242) and the power receiving device 21 and the power storage device 22, and the DC / DC converter 26 that is provided between the inverters 25 (first and second inverters 251 and 252) and the power storage device 22. Furthermore, the dump truck 2 is equipped with a resistor 27 that converts regenerative power generated by the regenerative braking of the traveling motor 24 into heat, a chopper circuit 28 that is provided between the resistor 27 and the traveling motor 24, and a control device 29. This control device 29 estimates and monitors the state of charge of the power storage device 22 based on the detection result of the sensor 23. When regenerative power is generated by the first and second traction motors 241, 242, the control device 29 controls the DC / DC converter 26 and the chopper circuit 28 to supply the regenerative power to the power storage device 22. When regenerative power is generated by the first and second traction motors 241, 242 and the state of charge of the power storage device 22 exceeds an upper limit, the control device 29 controls the DC / DC converter 26 and the chopper circuit 28 to supply the regenerative power to the resistor 27.

[0060] With this configuration, the dump truck 2 of this embodiment can activate the regenerative brake by the traveling motor 24 on the downhill slope M33 of the travel route M3, and dissipate the regenerative power into the atmosphere as heat, even if the charging rate of the power storage device 22 exceeds a predetermined upper limit. This eliminates the need to use the mechanical brake of the dump truck 2, thereby reducing the maintenance costs of the mechanical brake. Furthermore, it is not necessary to return the regenerative power generated by the traveling motor 24 to the trolley wire 31, and therefore it is not necessary to install a trolley wire 31 that takes into account the return of the regenerative power, for example, on the downhill slope M33.

[0061] As a result, it is possible to reduce the distance over which the trolley wire 31 is installed at mining sites MS, construction sites, etc., thereby reducing the installation and maintenance costs of the trolley wire 31. Furthermore, by reducing the distance over which the trolley wire 31 is installed, it becomes easier to install and move the trolley wire 31 at mining sites MS and construction sites where the topography changes from moment to moment, and the number of travel routes M3 that can have a small curvature without having to consider loss of contact with the trolley wire 31 increases.

[0062] Furthermore, by reducing the distance over which the trolley wire 31 is installed, it is possible to increase the travel route M3 where there is no need to consider separation from the trolley wire 31 due to unevenness in the road surface, and to reduce the frequency of maintenance of the travel route M3. Also, by eliminating the need for the trolley wire 31 other than on the uphill slope M31, the flexibility of the travel route M3 increases, and the productivity of the dump truck 2 can be improved.

[0063] In addition, by reducing the distance over which the contact wire 31 is installed, it is possible to reduce the risk of damage to the contact wire 31 and the substation M8 due to stones flying in due to blasting at a mining site MS or a construction site. Also, since the distance over which the pantograph 211 of the dump truck 2 must travel carefully to stay close to the contact wire 31 is reduced, the operator of the dump truck 2 can pay more attention to his surroundings, improving safety.

[0064] Moreover, the power supply system 1 of the present embodiment includes the dump truck 2 of the present embodiment described above, and a power supply device 3 that supplies power to the power receiving device 21 of the dump truck 2. With this configuration, the power supply system 1 of the present embodiment can supply power to the power receiving device 21 of the dump truck 2 by the power supply device 3, and can achieve the same effects as the dump truck 2 of the present embodiment described above.

[0065] Moreover, in the dump truck 2 of this embodiment, the sensor 23 includes a voltage sensor 231 that detects the voltage of the power supply path between the power receiving device 21 and the DC / DC converter 26. With this configuration, for example, when the power feeding device 3 is connected to the power receiving device 21 or when regenerative power is being generated in the traveling motor 24, the control device 29 of the dump truck 2 can estimate the state of charge of the power storage device 22 based on the voltage detected by the voltage sensor 231.

[0066] Furthermore, in the dump truck 2 of this embodiment, the sensor 23 includes a voltage sensor 232 that detects the voltage between the positive terminal 221 and the negative terminal 222 of the power storage device 22. With this configuration, the control device 29 of the dump truck 2 can more accurately estimate the state of charge of the power storage device 22 based on the voltage between the terminals of the power storage device 22 detected by the voltage sensor 232. The dump truck 2 is only required to have at least one of the voltage sensor 231 and the voltage sensor 232. By providing the voltage sensor 231 and monitoring the detected value thereof, it becomes possible for the control device 29 to accurately control the DC / DC converter 26 and the chopper circuit 28, for example, to distribute power from the power receiving device 21 to the traveling motor 24, the power storage device 22, and the resistor 27, and to distribute power from the traveling motor 24 to the power storage device 22 and the resistor 27, as described above.

[0067] In the dump truck 2 of this embodiment, the power receiving device 21 includes a pantograph 211 connected to the traveling motor 24 via the inverter 25 and connected to the power storage device 22 via the DC / DC converter .

[0068] That is, in the power supply system 1 of this embodiment, the power receiving device 21 of the dump truck 2 includes a pantograph 211 that is connected to the traveling motor 24 via an inverter 25 and is connected to the power storage device 22 via a DC / DC converter 26. Also, in the power supply system 1, the power supply device 3 includes a trolley wire 31 that is installed only on an uphill slope M31 included in the predetermined travel route M3 of the dump truck 2 to supply power to the pantograph 211 of the dump truck 2.

[0069] With this configuration, the power supply system 1 and dump truck 2 of this embodiment can supply power from the trolley wire 31 to the pantograph 211 to drive the travel motor 24 on the uphill slope M31, which consumes the most power in the travel route M3. Therefore, with the power supply system 1 and dump truck 2 of this embodiment, the trolley wire 31 is installed only on the uphill slope M31, reducing the distance of the trolley wire 31, while suppressing an increase in the weight of the power storage device 22 and maintaining the payload capacity of the dump truck 2 and, ultimately, productivity.

[0070] Moreover, in the power supply system 1 of this embodiment, as described above, the power receiving device 21 of the dump truck 2 includes the pantograph 211 that is connected to the traveling motor 24 via the inverter 25 and connected to the power storage device 22 via the DC / DC converter 26. Moreover, in the power supply system 1, the power supply device 3 includes the stationary charging overhead line 32 that is installed in a power supply area M9 that is off the predetermined travel route M3 of the dump truck 2 and supplies power to the pantograph 211.

[0071] With this configuration, it becomes possible to reduce the distance over which the trolley wire 31 is installed, while supplying power from the stationary charging overhead line 32 to the pantograph 211 of the dump truck 2 as needed to charge the power storage device 22. More specifically, the stationary charging overhead line 32 can be installed, for example, adjacent to a workshop M4 where maintenance of the dump truck 2 is performed or a parking lot M5 where operators of the dump truck 2 are changed over.

[0072] This allows charging of the power storage device 22 of the dump truck 2, whose charging time has been reduced due to the reduced installation distance of the trolley wire 31, in the power supply area M9, ​​which does not affect production at the mining site MS or construction work at the construction site. From the perspective of preventing overheating of the contact portion between the stationary charging overhead line 32 and the pantograph 211, it is preferable to supply power from the stationary charging overhead line 32 to the pantograph 211 while moving the dump truck 2 slightly or while cooling the contact portion.

[0073] Furthermore, in the dump truck 2 of this embodiment, the power receiving device 21 includes a charging port 213 that is directly connected to the positive terminal 221 and the negative terminal 222 of the power storage device 22. With this configuration, for example, in a workshop M4, a parking lot M5, or a vehicle body assembly site M6 where the dump truck 2 is assembled, an operator can connect a charging cable 341 of a low-voltage charging station 34 to the charging port 213 to charge the power storage device 22.

[0074] Furthermore, in the power supply system 1 of this embodiment, the power receiving device 21 of the dump truck 2 includes, as described above, the charging port 213 that is directly connected to the positive terminal 221 and the negative terminal 222 of the power storage device 22. Furthermore, in the power supply system 1 of this embodiment, the power supply device 3 includes a mobile charging vehicle 35 that supplies power to the charging port 213.

[0075] With this configuration, the power supply system 1 of this embodiment can move the mobile charging vehicle 35 to the vicinity of a dump truck 2 that has difficulty traveling due to a drop in the charge rate of the power storage device 22. Furthermore, the operator can connect the charging cable 351 of the mobile charging vehicle 35 that has stopped near the dump truck 2 to the charging port 213 of the dump truck 2, thereby charging the power storage device 22.

[0076] Furthermore, in the dump truck 2 of this embodiment, the power receiving device 21 includes a charging port 212 that is connected to a positive terminal 221 and a negative terminal 222 of the power storage device 22 via the DC / DC converter 26. With this configuration, the dump truck 2 of this embodiment can supply power from the high-voltage charging station 33 of the power feeding device 3 to the charging port 212, thereby charging the power storage device 22 in a short time. Note that, since charging of the power storage device 22 using the charging port 212 is performed via the DC / DC converter 26, the dump truck 2 needs to be in an activated state, not in a dormant state.

[0077] While the embodiments of the dump truck and power supply system according to the present disclosure have been described in detail above using the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not deviate from the gist of the present disclosure are also included in the present disclosure. For example, the power receiving device 21 of the dump truck 2 may include at least one of the pantograph 211, the first charging port 212, and the second charging port 213. [Explanation of symbols]

[0078] 1 Power supply system 2 dump trucks 21 Power receiving device 211 Pantograph 212 charging port 213 Charging port 22 Energy storage device 221 Positive terminal 222 Negative terminal 23 Sensors 231 Voltage Sensor 232 Voltage Sensor 24 Drive motor 25 inverter 26 DC / DC converters 27 Resistor 28 Chopper Circuit 29 Control Device 3 Power supply equipment 31 Trolley Wire 32 Stationary charging overhead line 35 Mobile charging vehicle M3 driving route M31 uphill M9 Power Supply Area

Claims

1. a power receiving device that receives power from an external source; a power storage device electrically connected to the power receiving device and charged by power supplied from the power receiving device; a sensor for detecting a voltage of the power storage device; first and second traction motors that are supplied with electric power from the power receiving device or the power storage device and rotate, and that generate regenerative electric power during braking; first and second inverters provided between the first and second traction motors, the power receiving device, and the power storage device; a DC / DC converter provided between the first and second inverters and the power storage device; a resistor electrically connected to the first and second traction motors and configured to convert the regenerative power generated by the first and second traction motors into heat; a chopper circuit provided between the resistor and the first and second traction motors; an auxiliary power device connected to a switch box provided in a power supply path between the power receiving device and the first inverter and in a power supply path between the second inverter and the DC / DC converter, and provided between the switch box and the DC / DC converter, the auxiliary power device receiving power from the power receiving device, power stored in the power storage device, or the regenerated power from the first and second traction motors, and supplying power to auxiliary devices; a control device that estimates a state of charge of the power storage device based on a detection result of the sensor, and controls the first and second inverters, the DC / DC converter, the chopper circuit, and the switch box based on the estimated state of charge; The control device When the regenerative electric power is generated by the first and second traction motors, when the charging rate of the power storage device is less than a predetermined upper limit value, the DC / DC converter and the chopper circuit are controlled to supply the regenerative power to the power storage device to charge the power storage device and also to supply the regenerative power to the auxiliary power device; when the charging rate is higher than the upper limit value, the DC / DC converter and the chopper circuit are controlled to supply the regenerative power to the resistor, and the switch box is controlled to interrupt the power supply path between the first and second traction motors and the power storage device, thereby stopping charging of the power storage device and supplying power from the power storage device to the auxiliary power device. A dump truck characterized by:

2. The dump truck according to claim 1 , wherein the sensor is a voltage sensor that detects a voltage in a power supply path between the power receiving device and the DC / DC converter.

3. The dump truck according to claim 1, wherein the sensor is a voltage sensor that detects a voltage between a positive terminal and a negative terminal of the power storage device.

4. The dump truck according to claim 1 , wherein the power receiving device includes a charging port directly connected to a negative terminal and a positive terminal of the power storage device.

5. The dump truck according to claim 1 , wherein the power receiving device includes a charging port connected to a negative terminal and a positive terminal of the power storage device via the DC / DC converter.

6. 2. The dump truck according to claim 1, wherein the power receiving device is a pantograph connected to the first and second travel motors via the first and second inverters and connected to the power storage device via the DC / DC converter.

7. A power supply system comprising: the dump truck according to any one of claims 1 to 6; and a power supply device that supplies electric power to the power receiving device of the dump truck.

8. the power receiving device is a pantograph connected to the first and second traction motors via the first and second inverters and connected to the power storage device via the DC / DC converter; The power supply system according to claim 7, wherein the power supply device is a contact wire that is installed only on an uphill slope included in a predetermined travel route of the dump truck and supplies power to the pantograph.

9. the power receiving device is a pantograph connected to the first and second traction motors via the first and second inverters and connected to the power storage device via the DC / DC converter; 8. The power supply system according to claim 7, wherein the power supply device is a stationary charging overhead line that is installed in a power supply area outside a predetermined travel route of the dump truck and supplies power to the pantograph.

10. the power receiving device includes a charging port directly connected to a negative terminal and a positive terminal of the power storage device, The power supply system according to claim 7, wherein the power supply device is a mobile charging vehicle that supplies power to the charging port.

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