Electric work vehicles

Abstract

To provide an electric work vehicle which downsizes a DC / DC converter and is capable of reducing loss or noise occurring when the vehicle stops or travels at a slow speed while stable power supply for an auxiliary machine is secured.SOLUTION: An electric work vehicle includes: a main machine DC line with which DC power generated by a power generator is supplied; an invertor which drives a traveling motor by DC power supplied by the main machine DC line; an auxiliary machine DC line supplying DC power for driving an auxiliary machine device; a DC / DC converter capable of converting DC voltage of the main machine DC line and supplying it for the auxiliary machine DC line when DC voltage of the main machine DC line is predetermined voltage threshold or higher; an auxiliary machine power supply which has a power storage device accumulating power that can be supplied for the auxiliary machine DC line; and a controller controlling the power generator and the auxiliary machine power supply. The controller controls the power generator and the auxiliary machine power supply in accordance with rotary speed of a traveling motor and a residual power storage amount of the power storage device.SELECTED DRAWING: Figure 1

Description

【Technical Field】 【0001】 The present invention relates to an electric work vehicle. 【Background Art】 【0002】 In recent years, against the backdrop of the depletion of fossil fuels and the worsening of global environmental problems, the popularity of electric vehicles that utilize electric energy, such as hybrid vehicles and electric cars, has been on the rise. For example, at mining sites, various electrically driven work vehicles are used, and as work vehicles for transportation, large electric work vehicles such as electric dump trucks are also being used. 【0003】 As a technology related to the power control of such electric vehicles, for example, the one described in Patent Document 1 is known. Patent Document 1 discloses a vehicle power system including a main battery that stores power for driving, an auxiliary battery that stores power for supplying to vehicle accessories, and a converter capable of performing bidirectional power conversion between the main battery and the auxiliary battery, and a controller for controlling the main battery, the auxiliary battery, and the converter. The controller is configured to supply power from the main battery to the auxiliary battery when a predetermined condition is satisfied, determine whether the vehicle power system is off, and when the vehicle power system is off, further determine whether the remaining charge of the main battery is less than a predetermined value, and when the remaining charge of the main battery is less than the predetermined value, the operation of the accessories is prohibited. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2020-43689 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 Electrically driven dump trucks are equipped with an electric drive system that converts the power generated by the main generator connected to the engine using an inverter to drive the drive motor connected to the main DC line, and also converts the power from the main DC line using a DC / DC converter to supply it to the auxiliary DC line, driving auxiliary equipment such as the air conditioner compressor motor system and the cooling blower motor system. 【0006】 In large electric work vehicles such as electric-driven dump trucks used in mines, the power handled by the main DC line tends to increase in voltage as the capacity of the electric drive system increases. On the other hand, when the electric work vehicle is stopped or traveling at low speed, a relatively low voltage can be applied to the drive motor. Therefore, it is conceivable to change the voltage of the main DC line according to the speed. In other words, by controlling the voltage of the main DC line to a low level when stopped or traveling at low speed, losses and noise generated in the circuit on the main DC line side can be reduced. 【0007】 However, the DC / DC converter that converts the voltage of the power supplied from the main DC line to the auxiliary DC line becomes larger as the range of input voltages that the main DC line can handle widens. In other words, making the DC / DC converter compatible with a wide range of input voltages from high to low voltage leads to a larger DC / DC converter. 【0008】 On the other hand, it is conceivable to miniaturize the DC / DC converter by narrowing the range of input voltages that the DC / DC converter can handle. However, if the voltage on the main engine's DC line side falls below the range of input voltages that the DC / DC converter can handle, such as when the vehicle is stopped or traveling at low speeds, the DC / DC converter may become inoperable, potentially preventing power from being supplied to auxiliary equipment. 【0009】 The present invention has been made in view of the above, and aims to provide an electric work vehicle that can reduce losses and noise that occur when stopped or driving at low speeds, while miniaturizing the DC / DC converter and ensuring a stable power supply to auxiliary equipment. [Means for solving the problem] 【0010】 The present invention includes multiple means for solving the above problems, but to give one example, the invention comprises a power generator, a main DC line to which DC power generated by the power generator is supplied, a travel motor, an inverter that drives the travel motor with DC power supplied to the main DC line, an auxiliary equipment, an auxiliary DC line that supplies DC power to drive the auxiliary equipment, a DC / DC converter that converts the DC voltage of the main DC line and supplies it to the auxiliary DC line when the DC voltage of the main DC line is above a predetermined voltage threshold, and an auxiliary power supply device that stores power that can be supplied to the auxiliary DC line, and a control device that controls the power generator and the auxiliary power supply device, wherein the control device controls the power generator and the auxiliary power supply device according to the rotational speed of the travel motor and the remaining amount of charge stored in the charge storage device. [Effects of the Invention] 【0011】 According to the present invention, it is possible to miniaturize the DC / DC converter, ensure a stable power supply to auxiliary equipment, and reduce losses and noise that occur when the vehicle is stopped or driving at low speeds. [Brief explanation of the drawing] 【0012】 [Figure 1] This is a schematic diagram illustrating the electric drive system of an electric-powered dump truck. [Figure 2] This diagram schematically shows the configuration of the auxiliary power supply unit. [Figure 3] This diagram schematically shows the configuration of the first DC / DC converter. [Figure 4] This is a functional block diagram that schematically shows the processing contents of the control unit. [Figure 5] It is a functional block diagram schematically showing the processing content of the main machine voltage command generation unit. [Figure 6] It is a flowchart showing the processing content of the main machine voltage command generation unit. [Figure 7] It is a functional block diagram schematically showing the processing content of the power generation device control unit and the power consumption device control unit. [Figure 8] It is a functional block diagram schematically showing the processing content of the first DC / DC converter control unit. [Figure 9] It is a diagram schematically showing the configuration of the auxiliary power supply device according to the second embodiment. [Figure 10] It is a diagram schematically showing the configuration of the second DC / DC converter. [Figure 11] It is a functional block diagram schematically showing the processing content of the control device according to the second embodiment. [Figure 12] It is a functional block diagram schematically showing the processing content of the first DC / DC converter control unit according to the second embodiment. [Figure 13] It is a functional block diagram schematically showing the second DC / DC converter control unit. [Figure 14] It is a diagram schematically showing the configuration of the auxiliary power supply device according to the third embodiment. [Figure 15] It is a functional block diagram schematically showing the processing content of the control device according to the third embodiment. [Figure 16] It is a functional block diagram schematically showing the second DC / DC converter control unit according to the third embodiment. [Figure 17] It is a side view schematically showing the appearance of an electric drive dump truck shown as an example of an electric working vehicle. 【Embodiments for Carrying out the Invention】 【0013】 Hereinafter, embodiments of the present invention will be described while referring to the drawings. In this embodiment, an electric dump truck is shown and described as an example of an electric work vehicle. However, the present invention can also be applied to other electric work vehicles such as an electric wheel loader, for example. 【0014】 <First Embodiment> The first embodiment of the present invention will be described while referring to FIGS. 1 to 8 and FIG. 17. 【0015】 FIG. 17 is a side view schematically showing the appearance of the electric dump truck according to this embodiment. FIG. 1 is a diagram schematically showing the electric drive system of the electric dump truck. In FIG. 17, only one of the pair of left and right configurations of the driven wheels, drive wheels, traveling motors, etc. is shown and labeled, and for the other, only the label is shown in parentheses in the figure and the illustration is omitted. 【0016】 In FIG. 17, the electric dump truck 100 includes a vehicle body frame 1 extending in the front-rear direction to form a support structure, a loading platform (bed) 5 disposed on the upper part of the vehicle body frame 1 so as to extend in the front-rear direction, and the lower part of the rear end thereof is provided on the vehicle body frame 1 via a pin joint portion 5a so as to be tiltable, a pair of driven wheels (front wheels) 2L and 2R provided on the left and right of the lower front side of the vehicle body frame 1, a pair of drive wheels (rear wheels) 3L and 3R provided on the left and right of the lower rear side of the vehicle body, a cab 4 provided on the upper front side of the vehicle body frame 1, a fuel tank 9 provided below the vehicle body frame 1, an engine 12 (see FIG. 1) disposed on the vehicle body frame 1 and driven by fuel supplied from the fuel tank 9, a main generator 13 (see FIG. 1) connected to and driven by the engine 12, etc., and is generally configured from an electric drive system (see FIG. 1) that supplies the electric power generated and output by the main generator 13 to traveling motors 10L and 10R that drive the wheels (drive wheels 3L and 3R), auxiliary equipment 31, etc. 【0017】 The drive motors 10L and 10R, along with a reduction gear (not shown), are housed in the rotating shafts of the drive wheels 3L and 3R and are driven by power supplied via the inverter 16. In Figure 1, for simplicity of illustration, some reference numerals have been omitted, and the left and right drive motors 10L and 10R are collectively referred to simply as "10". 【0018】 The vehicle frame 1 and the cargo bed 5 are connected via a hoist cylinder 6. The extension and retraction of the hoist cylinder 6 causes the cargo bed 5 to rotate around the pin joint 5a, raising and lowering the cargo bed 5 relative to the vehicle frame 1. 【0019】 The vehicle frame 1 is fitted with a deck and steps that the operator can walk on, and the operator can move to the driver's cab 4 via these decks and steps. Inside the driver's cab 4 are an accelerator pedal, a brake pedal, a hoist pedal, a steering wheel, etc. (not shown). The operator controls the acceleration and braking force of the electric-driven dump truck 100 by pressing the accelerator pedal and brake pedal inside the driver's cab 4, performs hydraulic steering by turning the steering wheel left and right, and performs hydraulic dumping of the cargo bed 5 by pressing the hoist pedal. 【0020】 Behind the driver's cab 4 are a control cabinet 8 housing various power equipment and multiple grid boxes 7 for dissipating excess energy as heat using power consumption devices 17 (see Figure 1). Although not shown in Figure 17, the engine 12 and main generator 13 shown in Figure 1 are mounted on the vehicle frame 1 located between the left and right front wheels 2L and 2R. 【0021】 In Figure 1, the electric drive system of the electric drive dump truck 100 includes a main generator 13 connected to the engine 12, a rectifier circuit 14 connected to the main generator 13 that rectifies the output of the main generator 13 and outputs it as DC power to the main DC line 15, an inverter 16 for the travel motors connected between the main DC line 15 and the travel motors 10L and 10R, a power consumption device 17 capable of consuming the power of the main DC line 15, an auxiliary device 31, an auxiliary DC line 30 that supplies DC power to drive the auxiliary device 31, an auxiliary power supply device 20 having a DC / DC converter that can convert the voltage of the DC power of the main DC line 15 and supply it to the auxiliary DC line 30 when the voltage of the DC power of the main DC line 15 is above a predetermined voltage threshold (described later), and a control device 40 that controls the operation of the main generator 13, the auxiliary power supply device 20, etc. 【0022】 The power generation device 11 consists of an engine 12, a main generator 13, and a rectifier circuit 14, and generates the main voltage VM in the main DC line 15 by supplying power to the main DC line 15. 【0023】 The DC input of the inverter 16 for the traction motor is connected to the main DC line 15. The AC output of the inverter 16 is connected to the traction motor 10. 【0024】 A current detector 50 is provided between the inverter 16 and the travel motor 10 to detect the current IM supplied from the inverter 16 to the travel motor 10 and transmit the detected value to the control device 40. A speed detector 51 is also provided on the travel motor 10 to detect the rotational speed NM of the travel motor 10 and transmit the detected value to the control device 40. In Figure 1, one current detector 50 and one detection signal line are shown for detecting the current IM, but the system may be configured to detect at least two phases of the three-phase AC current flowing through the travel motor 10. Furthermore, if there are multiple travel motors, the system may be configured to detect the current and rotational speed for all of them. 【0025】 In addition to the inverter 16, a power consumption device 17 for consuming the regenerative power of the drive motor 10 is connected to the main DC line 15. The power consumption device 17 consists of a chopper circuit comprising a switching element 171 and a diode 172, a resistor 173, and a drive control device 174 that drives the switching element 171 based on a control signal CSR (described later) from the control device 40. 【0026】 A voltage detector 18 is provided in the main DC line 15 to detect the main voltage VM, which is the DC voltage generated in the main DC line 15, and transmit the detected value to the control device 40. A capacitor 19 is also provided in the main DC line 15 to smooth the main voltage VM. 【0027】 The input section of the auxiliary power supply unit 20 is connected to the main DC line 15, and the output section is connected to the auxiliary DC line 30. 【0028】 Auxiliary equipment 31 includes, for example, an inverter and compressor motor system for an air conditioner, or an inverter and blower motor system for equipment cooling. In Figure 1 of this embodiment, for the sake of simplicity of explanation, these loads are combined into a single equivalent impedance and shown as auxiliary equipment 31. 【0029】 The auxiliary DC line 30 is equipped with a voltage detector 32, which detects the auxiliary voltage VA, a DC voltage generated in the auxiliary DC line 30, and transmits the detected value to the control device 40. The auxiliary DC line 30 is also equipped with a capacitor 33 for smoothing the auxiliary voltage VA. 【0030】 Although not shown in Figure 1 or the above explanation, capacitor discharge resistors, surge protectors such as varistors and arresters may be connected to the main DC line 15 and the auxiliary DC line 30. Furthermore, fuses, reactors, and switches (such as electromagnetic contactors and circuit breakers) may be inserted when connecting each device to the main DC line 15 and the auxiliary DC line 30. 【0031】 Furthermore, while IGBTs (Insulated Gate Bipolar Transistors) are used as examples of switching elements for the inverter 16 and power consumption device 17, and the circuit symbol for an IGBT is shown in Figure 1, the invention is not limited to these. For example, other types of elements such as MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors), bipolar transistors, and thyristors may be used as switching elements. 【0032】 Furthermore, while Figure 1 shows the circuit symbol for a diode as an example of using a diode as the rectifier circuit 14, it is not limited to this. For example, an AC / DC converter using a switching element may be used as the rectifier circuit 14. 【0033】 In the following explanation, the main generator 13 is described as a wound-excited synchronous generator with an excitation device that acts as an actuator. However, as mentioned above, an AC / DC converter may be used as the rectifier circuit 14, and other types of generators such as permanent magnet synchronous generators may also be used. 【0034】 The control device 40 receives the detected values ​​from the voltage detector 18 (main engine voltage VM), the voltage detector 32 (auxiliary equipment voltage VA), the current detector 50 (current IM), and the speed detector 51 (rotational speed NM). The control device 40 also receives the vehicle information signal DSV from an external higher-level control system. In Figure 1, the vehicle information signal DSV is shown as a single signal line, but the vehicle information signal DSV includes multiple pieces of information, such as vehicle speed information and operator input information (accelerator pedal operation amount DSACL and brake pedal operation amount DSBRK). The control device 40 also receives the detection signal DSA from the auxiliary power supply unit 20. 【0035】 The control device 40 controls the voltage and power flow within the electric drive system by generating and transmitting control signals for each device based on the detected values ​​(detection signals VM, VA, IM, NM) from each detector 18, 32, 50, 51 and the signals DSV, DSA. The control signals generated and transmitted by the control device 40 include the control signal CSE for the engine 12, the control signal CSI for the inverter 16, the control signal CSR for the power consumption device 17, the control signal CSA for the auxiliary power supply device 20, and the control signal VFref for the main generator 13. For example, the control signal VFref for the main generator 13 is the command value for the excitation voltage, and the excitation device of the main generator 13 controls the excitation voltage according to the value of the control signal (excitation voltage) VFref. In Figure 1, these control signals are each shown with a single arrow, but each signal may contain multiple pieces of information. 【0036】 The method of implementing the control device 40 is arbitrary, but for example, it can be implemented as an electronic circuit by mounting devices such as a CPU (Central Processing Unit), DSP (Digital Signal Processor), microcomputer, and FPGA (Field-Programmable Gate Array) on a board. Also, since the control device 40 has multiple arithmetic blocks, each arithmetic block may be mounted on a separate board or device. Alternatively, a single arithmetic block may be divided and mounted on multiple boards or devices. 【0037】 Figure 2 is a schematic diagram showing the configuration of the auxiliary power supply unit. 【0038】 In Figure 2, the auxiliary power supply unit 20 comprises a first DC / DC converter 21 and an energy storage device 60. 【0039】 The input section of the first DC / DC converter 21 is connected to the main DC line 15, and its output section is connected to the auxiliary DC line 30. The energy storage device 60 is also connected to the auxiliary DC line 30. 【0040】 The energy storage device 60 consists of an energy storage device 61, switches 62 and 63, a resistor 64, a voltage detector 65, and a current detector 66. 【0041】 The energy storage device 61 may be a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery, or a capacitor such as an electric double-layer capacitor or a lithium-ion capacitor. 【0042】 Switches 62 and 63 are arranged in series between the energy storage device 61 and the auxiliary DC line 30, with a resistor 64 connected in parallel to switch 63. Switch 62 opens and closes the connection between the energy storage device 61 and the auxiliary DC line 30. The parallel configuration of switch 63 and resistor 64 functions as an initial charging circuit for the capacitor 33 of the auxiliary DC line 30. When switches 62 and 63 are open, first, when switch 62 is closed, power from the energy storage device 61 charges the capacitor 33 via resistor 64, and the auxiliary voltage VA increases to the same level as the DC voltage VB of the input / output section of the energy storage device 61. Then, when switch 63 is closed, resistor 64 is bypassed. These switch operations are performed after the electric drive dump truck 100, which is an electric work vehicle, is started. Also, since the auxiliary voltage VA is equal to the voltage VB of the energy storage device 61, the voltage specifications of the energy storage device 61 are determined so that the voltage VB is within the operating voltage range of the auxiliary equipment 31. Furthermore, when connecting the energy storage device 60 to the auxiliary DC line 30, fuses or circuit breakers may be inserted. 【0043】 Switches 62 and 63 are explained using examples such as electromagnetic contactors and electromagnetic switches, but coils, drive circuits, etc. are not shown in the diagram. Switches 62 and 63 are controlled to open and close by control signals CSS1 and CSS2, respectively. The control signals CSS1 and CSS2 transmitted to switches 62 and 63, and the control signal CSD1 (described later) transmitted to the first DC / DC converter 21 are included in the control signal CSA transmitted from the control device 40 to the auxiliary power supply unit 20. 【0044】 A voltage detector 65 and a current detector 66 are provided between the energy storage device 61 and the auxiliary DC line 30 (i.e., at the input / output section of the energy storage device 61). These detectors detect the voltage VB, which is the DC voltage at the input / output section of the energy storage device 61, and the charge / discharge current IB, which is the DC current exchanged between the energy storage device 61 and the auxiliary DC line 30. These detected values ​​are then combined and transmitted to the control device 40 as a detection signal DSA. 【0045】 As described above, the auxiliary power supply unit 20 can drive the auxiliary equipment 31 and charge the energy storage device 61 using the output power from the first DC / DC converter 21. In addition, the auxiliary power supply unit 20 can also supply power to the auxiliary equipment 31 by discharging the energy storage device 61. 【0046】 Figure 3 is a schematic diagram showing the configuration of the first DC / DC converter. 【0047】 In Figure 3, the first DC / DC converter 21 converts the voltage of the DC power of the main DC line 15 (main voltage VM) to an auxiliary voltage VA and supplies it to the auxiliary DC line 30 when the voltage of the DC power of the main DC line 15 (main voltage VM) is above a predetermined voltage threshold (described later). It is generally composed of a full-bridge inverter 211 made up of four switching elements Q1, Q2, Q3, and Q4, a transformer 212, a full-bridge rectifier circuit 213 made up of four diodes D1, D2, D3, and D4, a choke coil 214, capacitors 215, 216, and a drive control device 217. 【0048】 The full-bridge inverter 211 converts the main motor voltage VM input from the main motor DC line 15 into an AC voltage VTR and applies it to the primary winding of the transformer 212 (on the main motor DC line 15 side). The transformer 212 insulates the input and output of the first DC / DC converter 21 (between the main motor DC line 15 and the auxiliary DC line 30) and transforms the voltage applied to the primary winding to generate an AC voltage on the secondary winding (on the auxiliary DC line 30 side). The AC voltage generated on the secondary winding of the transformer 212 is converted into a DC voltage by the full-bridge rectifier circuit 213 and output to the auxiliary DC line 30 as an auxiliary voltage VA via a filter circuit consisting of a choke coil 214 and a capacitor 216. In other words, the first DC / DC converter 21 can insulate the main motor DC line 15 and the auxiliary DC line 30 by using the transformer 212. Furthermore, even when there is a large difference between the main voltage VM of the main DC line 15 and the auxiliary voltage VA of the auxiliary DC line 30, the current flowing through the primary circuit can be reduced by using the transformer 212. 【0049】 The drive control device 217 outputs a drive voltage for each element constituting the first DC / DC converter 21 based on the control signal CSD1 input from the control device 40. For example, if the first DC / DC converter 21 is configured to control each element on and off based on pulse width modulation (PWM), the control signal CSD1 will be a PWM duty cycle or a PWM signal. 【0050】 In Figure 3, an example is shown where an IGBT is used as the switching element, but the system is not limited to this, and other types of switching elements such as MOSFETs may be used. In addition to the above configuration, the system may also include switches, protective components such as fuses and surge protectors, and noise filters. Furthermore, in Figure 3 and Figure 2 above, the control signal CSD1 is shown with a single arrow, but the control signal CSD1 may contain multiple pieces of information. For example, if the first DC / DC converter 21 has multiple switching elements, the control signal CSD1 is configured as a set of control signals for each element. 【0051】 Here, we will explain the variable range of the main motor voltage VM of the main motor DC line 15 and the input voltage range of the first DC / DC converter. 【0052】 In the electric drive system according to this embodiment shown in Figure 1, the main motor voltage VM of the main motor DC line 15 is controlled by the generator 11 or the power consumption device 17. When the travel motor 10 is stopped or in operation, the main motor voltage VM is controlled by the generator 11. Furthermore, during regeneration of the travel motor 10, the output of the generator 11 is not required, and the main motor voltage VM is controlled by the power consumption device 17. 【0053】 As mentioned above, when the electric-driven dump truck 100 is a large electric work vehicle such as a mining dump truck, the main motor voltage VM tends to be high. On the other hand, even with a large electric work vehicle, when stopped or traveling at low speed, the voltage that the inverter 16 should apply to the travel motor 10 is relatively low. 【0054】 Therefore, in this embodiment, the maximum and minimum values ​​of the main motor voltage VM are set to VMmax and VMmin, respectively, and the main motor voltage VM is changed according to the speed of the electric drive dump truck 100 (in this case, the rotational speed NM of the travel motor 10). This allows the main motor voltage VM to be controlled to a low value when stopped or traveling at low speed, thereby reducing losses and noise generated in the main motor circuits such as the inverter 16 and power consumption device 17. 【0055】 On the other hand, if the configuration is such that the main motor voltage VM is varied, the first DC / DC converter 21 needs to have a wide input voltage specification that can accommodate the range of variation of the main motor voltage VM. Furthermore, the wider the range of input voltage specifications, the larger the first DC / DC converter 21 becomes. Specifically, since the amplitude of the current flowing through the primary side circuit of the transformer 212 increases, the transformer 212, the full-bridge inverter 211, and the cooling system (not shown) need to be made larger to withstand this current. Also, when the main motor voltage VM is low, the input current of the first DC / DC converter 21 increases, so the switches and fuses in the input section (not shown) need to be made larger. 【0056】 In this embodiment, in order to avoid increasing the size of the first DC / DC converter 21, the first DC / DC converter 21 is miniaturized by limiting the range in which it performs power conversion operations to when the main voltage VM is above a predetermined lower voltage limit (threshold voltage) VDmin. At this time, the first DC / DC converter 21 can be made even smaller by setting the lower voltage limit (threshold voltage) VDmin higher than the minimum value VMmin of the main voltage VM, and then setting the lower voltage limit VDmin even higher. In addition, when the main voltage VM is in a range in which the first DC / DC converter 21 does not supply power from the main DC line 15 to the auxiliary DC line 30 (i.e., when the lower voltage limit VDmin > main voltage VM ≥ minimum value VMmin), power is supplied from the energy storage device 61 to the auxiliary equipment 31 as needed. The control of the electric drive system according to this embodiment is realized by the control device 40. 【0057】 Figure 4 is a functional block diagram that schematically shows the processing contents of the control device. 【0058】 In Figure 4, the control device 40 is composed of a drive control unit 41, an SoC calculation unit 42, a main motor voltage command generation unit 43, a power generation device control unit 44, a power consumption device control unit 45, a first DC / DC converter control unit 46, and a power storage device switch control unit 47. 【0059】 The drive control unit 41 generates control signals CSE and CSI according to the operation input information, such as the accelerator pedal operation amount DSACL and brake pedal operation amount DSBRK, included in the vehicle information signal DSV from the higher-level control system, and outputs them to the engine 12 and inverter 16, respectively. This allows the vehicle to be appropriately accelerated or decelerated according to the accelerator pedal operation amount DSACL and brake pedal operation amount DSBRK. 【0060】 The SoC calculation unit 42 calculates the remaining capacity SoC (State of Charge) of the energy storage device 61 and outputs it to the main voltage command generation unit 43 and the first DC / DC converter control unit 46. The calculation method for the remaining capacity SoC uses either a method that utilizes the relationship between the voltage value VB of the energy storage device 61 and the remaining capacity SoC, or a method that determines the change in the remaining capacity SoC from the integral value of the current value IB of the energy storage device 61. The SoC calculation unit 42 calculates the remaining capacity SoC using the input voltage value VB and current value IB. 【0061】 The main engine voltage command generation unit 43 generates a command value (main engine DC voltage command value VMref) related to the main engine voltage Vm according to the rotational speed NM of the travel motor 10 and the remaining capacity SoC, and outputs it to the power generation device control unit 44 and the power consumption device control unit 45. In Figure 4, the rotational speed NM of the travel motor 10 detected by the speed detector 51 is shown as an example of the speed input to the main engine voltage command generation unit 43, but it is not limited to this, and if the speed of the travel motor 10 or the electric drive dump truck 100 can be detected or estimated by means other than the speed detector 51, those values ​​may be input to the main engine voltage command generation unit 43 instead of the rotational speed NM, and the main engine DC voltage command value VMref may be calculated. 【0062】 The power generation device control unit 44 performs calculations to ensure that the main motor voltage VM matches the main motor DC voltage command value VMref, generates a control signal VFref which is the manipulated variable of the power generation device 11, and outputs it to the main motor generator 13 of the power generation device 11. 【0063】 The power consumption device control unit 45, similar to the power generation device control unit 44, performs calculations to control the main engine voltage VM based on the main engine DC voltage command value VMref, generates a control signal CSR for the power consumption device 17, and outputs it to the drive control device 174. However, as will be described later, the command value of the main engine voltage VM is changed from the main engine DC voltage command value VMref. 【0064】 The first DC / DC converter control unit 46 generates a control signal CSD1 for the first DC / DC converter 21 based on the remaining capacitance SoC, current value IB, and main voltage VM, and outputs it to the drive control device 217. Specifically, it generates a command value IBref for the current value IB based on the remaining capacitance SoC, performs current control calculations to control the current value IB according to the command value IBref, and performs on / off control based on the main voltage VM, and as a result of these, the control signal CSD1 is generated. 【0065】 The energy storage device switch control unit 47 generates control signals CSS1 and CSS2 based on the vehicle information signal DSV, the auxiliary voltage VA, and the voltage VB of the energy storage device 61, and outputs them to switches 62 and 63, respectively. Specifically, when the energy storage device switch control unit 47 detects the start of the electric drive dump truck 100 based on the vehicle information signal DSV, it generates (modifies) control signal CSS1 to close switch 62. Subsequently, when it detects that the auxiliary voltage VA has increased to approximately the same level as voltage VB, it generates (modifies) control signal CSS2 to close switch 63. The energy storage device switch control unit 47 may also be equipped with a function to generate (modify) control signal CSS1 to open switch 62 if it detects an abnormality in the vehicle based on the vehicle information signal DSV. 【0066】 Figure 5 is a functional block diagram schematically showing the processing contents of the main engine voltage command generation unit. Figure 6 is a flowchart showing the processing contents of the main engine voltage command generation unit. 【0067】 As shown in Figure 5, the main engine voltage command generation unit 43 includes a main engine voltage command table 431, a main engine voltage command limiter 432, and a main engine voltage command selection unit 433. 【0068】 The main motor voltage command table 431 is a table that sets the relationship between the rotational speed NM of the travel motor 10 and the first provisional value VMref1 of the main motor DC voltage command value VMref. In Figure 5, the vertical axis of the main motor voltage command table 431 shows the first provisional value VMref1 and the horizontal axis shows the rotational speed NM. In the main motor voltage command table 431, the first provisional value VMref1 takes its minimum value VMmin until the rotational speed NM goes from 0 to a predetermined rotational speed N1. When the rotational speed NM exceeds the rotational speed N1, the first provisional value VMref1 increases in accordance with the increase in rotational speed NM, and when the rotational speed NM is equal to or greater than the predetermined rotational speed N2, the first provisional value VMref1 takes its maximum value VMmax. Here, when the rotational speed NM is at the rotational speed threshold Nth, the first provisional value VMref1 takes its lower voltage limit VDmin. That is, when the rotational speed NM is lower than the rotational speed threshold Nth, the first provisional value VMref1 is lower than the lower voltage limit VDmin. Furthermore, a voltage value (first voltage value V1) was set as a value greater than or equal to the lower voltage limit VDmin. 【0069】 The main engine voltage command limiter 432 is a table in which the relationship between the first provisional value VMref1 and the second provisional value VMref2 is set, and it generates the second provisional value VMref2 of the main engine DC voltage command value VMref by limiting the first provisional value VMref1. In Figure 5, the second provisional value VMref2 is shown on the vertical axis and the first provisional value VMref1 is shown on the horizontal axis of the main engine voltage command limiter 432. In the main engine voltage command limiter 432, the second provisional value VMref2 takes the voltage value V1 (i.e., the first voltage value V1) until the first provisional value VVMref1 goes from 0 to the first voltage value V1, and when the first provisional value VMref1 becomes greater than or equal to the voltage value V1, the second provisional value VMref2 takes the same value as the first provisional value VMref1. In other words, the main engine voltage command limiter 432 performs limiting so that the lower limit of the second provisional value VMref2 is the first voltage value V1. As a result, even if the rotational speed NM is lower than the rotational speed threshold Nth, and the first provisional value VMref1 is lower than the voltage lower limit VDmin, the second provisional value VMref2 will be set to the first voltage value V1, which is set to be higher than or equal to the voltage lower limit VDmin. 【0070】 The main motor voltage command selection unit 433 selects either the first provisional value VMref1 or the second provisional value VMref2 based on the remaining capacity SoC and outputs it as the main motor DC voltage command value VMref. Specifically, if the remaining capacity SoC is greater than or equal to the remaining capacity threshold Sth, the main motor voltage command selection unit 433 selects the first provisional value VMref1 as the main motor DC voltage command value VMref, and if the remaining capacity SoC is less than the remaining capacity threshold Sth, it selects the second provisional value VMref2 as the main motor DC voltage command value VMref. 【0071】 As shown in Figure 6, when the main motor voltage command generation unit 43 obtains the rotational speed NM of the travel motor 10 (step S100), it refers to the main motor voltage command table 431 to obtain a first provisional value VMref1 (step S110), and then refers to the main motor voltage command limiter 432 to generate a second provisional value VMref2 (step S120). 【0072】 Next, the remaining capacity SoC of the energy storage device 61 is obtained (step S130), and it is determined whether the remaining capacity SoC is equal to or greater than the remaining capacity threshold Sth (step S140). 【0073】 If the result of the determination in step S140 is YES, that is, if the remaining capacity SoC is equal to or greater than the remaining capacity threshold Sth, it is determined that the remaining capacity SoC of the energy storage device 61 is sufficient, and a first provisional value VMref1, in which the main motor voltage VM may be less than the voltage lower limit VDmin, that is, in which there may be no power supply to the auxiliary DC line 30 by the auxiliary power supply unit 20, is set as the main motor DC voltage command value VMref (step S150), and the process is terminated. 【0074】 Furthermore, if the determination result in step S140 is NO, that is, if the remaining capacity SoC is smaller than the remaining capacity threshold Sth, it is determined that the remaining capacity SoC of the energy storage device 61 is insufficient, and a second provisional value VMref2 is set as the main DC voltage command value VMref, which is such that the main voltage VM will not fall below the lower voltage limit VDmin, i.e., power will be supplied to the auxiliary DC line 30 by the auxiliary power supply unit 20 (step S151), and the process is terminated. 【0075】 In the main engine voltage command generation unit 43 configured as described above, if the rotational speed NM is lower than the rotational speed threshold Nth and the remaining capacity SoC is greater than or equal to the remaining capacity threshold Sth, the main engine DC voltage command value VMref will be lower than the voltage lower limit VDmin. On the other hand, if the remaining capacity SoC is smaller than the remaining capacity threshold Sth, the main engine DC voltage command value VMref will be greater than or equal to the first voltage value V1, even if the rotational speed NM is lower than the rotational speed threshold Nth. Here, since the first voltage value V1 is set to a value greater than or equal to the voltage lower limit VDmin, the main engine DC voltage command value VMref will also be greater than or equal to the voltage lower limit VDmin. 【0076】 Figure 7 is a functional block diagram that schematically shows the processing contents of the power generation device control unit and the power consumption device control unit. 【0077】 In Figure 7, the power generation device control unit 44 includes a voltage control calculation unit 441 and a calculation unit 442. 【0078】 The power generation device control unit 44 calculates the difference (VMref-VM) between the main engine DC voltage command value VMref and the main engine voltage VM in the calculation unit 442, and then generates a control signal VFref in the voltage control calculation unit 441 based on the calculation result. 【0079】 The voltage control calculation unit 441 generates (changes) a control signal VFref to reduce the deviation between the main engine voltage VM and the main engine DC voltage command value VMref, for example, by using a control law such as proportional-integral (PI) control. Specifically, if the main engine voltage VM < main engine DC voltage command value VMref, the control signal VFref is increased to increase the output of the power generator 11. 【0080】 Furthermore, in Figure 7, the power consumption device control unit 45 includes a voltage control calculation unit 451 and calculation units 452 and 453. 【0081】 The power consumption device control unit 45 first generates a command value VMrefR for the power consumption device by adding a predetermined voltage command offset ΔV (>0) to the main engine DC voltage command value VMref in the calculation unit 452. Next, the calculation unit 453 calculates the difference (VM-VMrefR) between the main engine voltage VM and the command value VMrefR, and then the voltage control calculation unit 451 generates a control signal CSR based on the calculation result. Here, the control signal CSR is assumed to be a PWM signal for turning the switching elements of the power consumption device 17 on and off. 【0082】 The voltage control calculation unit 451 uses a control law such as PI control to change the PWM duty cycle of the control signal CSR to reduce the deviation between the main engine voltage VM and the command value VMrefR. Specifically, if the main engine voltage VM > command value VMrefR, the PWM duty cycle is increased to increase the power consumption of the power consumption device 17. 【0083】 In this embodiment, the power generator control unit 44 and power consumption device control unit 45 are configured as described above. By using the voltage command offset ΔV to set the command value VMrefR > main engine DC voltage command value VMref, the power generator 11 controls the main engine voltage VM to the main engine DC voltage command value VMref when the travel motor 10 is stopped or in operation, and the power consumption of the power consumption device 17 becomes zero. Furthermore, during regeneration of the travel motor 10, the power consumption device 17 controls the main engine voltage VM to the command value VMrefR, and the power generator 11 reduces its output to zero. 【0084】 Figure 8 is a functional block diagram that schematically shows the processing contents of the first DC / DC converter control unit. 【0085】 In Figure 8, the first DC / DC converter control unit 46 includes a current command generation unit 461 and a current control system 462. 【0086】 The current command generation unit 461 generates a command value for current IB (current command value IBref) based on the remaining capacity SoC and outputs it to the current control system 462. Specifically, if the remaining capacity SoC is less than the upper limit (remaining capacity upper limit Smax), the current command value IBref is set to a predetermined negative command value I1 in order to charge the energy storage device 61. If the remaining capacity SoC is equal to or greater than the remaining capacity upper limit Smax, the current command value IBref is set to 0 (zero) in order to stop charging the energy storage device 61. Note that when current IB takes a negative value, it represents the charging current. 【0087】 The current control system 462 generates a control signal CSD1 based on the current command value IBref, current IB, and main motor voltage VM, and includes a current control calculation unit 463, an on / off control unit 464, and a calculation unit 465. 【0088】 The current control system 462 calculates the difference (IB-IBref) between the current IB and the current command value IBref in the calculation unit 465, and then generates a provisional signal CSD1temp of the control signal CSD1 in the current control calculation unit 463 based on the calculation result. The control signal CSD1 and the provisional signal CSD1temp are PWM signals for turning the switching elements of the first DC / DC converter 21 on and off, respectively. Specifically, the current control calculation unit 463 uses a control law such as PI control to change the PWM duty cycle of the provisional signal CSD1temp to reduce the difference between the current IB and the current command value IBref. For example, if current IB > current command value IBref, it means that the charging current is insufficient and that it is necessary to decrease the current IB (increase the charging current). In this case, the PWM duty cycle is changed so that the output current from the first DC / DC converter 21 to the auxiliary DC line 30 increases. At this time, assuming that the input current from the auxiliary DC line 30 to the auxiliary device 31 is constant, an increase in the output current from the first DC / DC converter 21 will increase the charging current to the energy storage device 61 (i.e., the current IB will decrease). 【0089】 The ON / OFF control unit 464 controls the ON / OFF state of the first DC / DC converter 21 based on the main motor voltage VM. Specifically, when the main motor voltage VM is greater than or equal to the lower voltage limit VDmin, the first DC / DC converter 21 can convert the voltage of the DC power of the main motor DC line 15 and output it to the auxiliary DC line 30, and outputs the provisional signal CSD1temp as the control signal CSD1. If the main motor voltage VM is less than the lower voltage limit VDmin, the first DC / DC converter 21 does not convert the voltage of the DC power of the main motor DC line 15 (and cannot supply power to the auxiliary DC line 30). In this case, regardless of the PWM duty cycle of the provisional signal CSD1temp, the control signal CSD1 is generated and output so that all switching elements of the first DC / DC converter 21 are turned off. 【0090】 The effects of this embodiment, configured as described above, will now be explained. 【0091】 In this embodiment, the first DC / DC converter 21 can output power to the auxiliary DC line 30 when the main voltage VM is higher than a predetermined lower voltage limit VDmin. Furthermore, by limiting the range of main voltage VM that the first DC / DC converter 21 can output in this way, the first DC / DC converter 21 can be miniaturized. 【0092】 The control device 40 controls the power generator 11 so that the main motor voltage VM is lower than the lower voltage limit VDmin when the rotational speed NM of the travel motor 10 is lower than a predetermined rotational speed threshold Nth, and the remaining capacity SoC of the energy storage device 61 is equal to or greater than a predetermined remaining capacity threshold Sth. In other words, by reducing the main motor voltage VM, taking into account that the voltage to be applied to the travel motor 10 can be relatively low when the rotational speed is low, losses and noise generated in the circuit configuration on the main DC line 15 side can be reduced. In addition, the voltage applied to the switching elements on the main DC line 15 side is reduced, and a sufficient margin for withstand voltage can be secured. At this time, although the first DC / DC converter 21 cannot supply DC power to the auxiliary DC line 30, the auxiliary equipment 31 can be stably driven by discharge from the energy storage device 60 because there is sufficient remaining capacity SoC of the energy storage device 61. 【0093】 When the remaining capacity SoC of the energy storage device 61 is less than a predetermined remaining capacity threshold Sth, the control device 40 controls the generator 11 so that the main voltage VM becomes equal to or greater than the first voltage value V1, and controls the auxiliary power supply unit 20 to charge the energy storage device 61. The first voltage value V1 is set to a value equal to or greater than the lower voltage limit VDmin. At this time, the first DC / DC converter 21 can supply power to the auxiliary DC line 30, so that the auxiliary equipment 31 can be stably driven by the output of the first DC / DC converter 21 while the energy storage device 61 is charged. 【0094】 In this way, when the remaining capacity of the energy storage device 61 SoC becomes small, the first DC / DC converter 21 can be operated to charge it, so the capacity of the energy storage device 61 can be kept to the minimum necessary, and the energy storage device 61 can be miniaturized. 【0095】 In other words, in this embodiment, the DC / DC converter can be miniaturized, and while ensuring a stable power supply to auxiliary equipment, losses and noise that occur when the vehicle is stopped or driving at low speeds can be reduced. 【0096】 <Second Embodiment> A second embodiment of the present invention will be described with reference to Figures 9 to 13. 【0097】 This embodiment adds a second DC / DC converter 67 between the energy storage device 61 and the switch 63, in addition to the configuration of the first embodiment. In this embodiment, the same reference numerals are used for components similar to those in the first embodiment, and their descriptions are omitted as appropriate. 【0098】 Figure 9 is a schematic diagram showing the configuration of the auxiliary power supply device according to this embodiment. 【0099】 In Figure 9, the auxiliary power supply unit 20A comprises a first DC / DC converter 21 and an energy storage device 60A. 【0100】 The input section of the first DC / DC converter 21 is connected to the main DC line 15, and its output section is connected to the auxiliary DC line 30. The energy storage device 60A is also connected to the auxiliary DC line 30. 【0101】 The energy storage device 60A consists of an energy storage device 61, switches 62 and 63, a resistor 64, a voltage detector 65, a current detector 66, and a second DC / DC converter 67. 【0102】 In the energy storage device 60A, the second DC / DC converter 67 is connected between the energy storage device 61 and the switch 63. The control signal CSA includes the control signal CSD2 of the second DC / DC converter 67. The second DC / DC converter 67 is a bidirectional DC / DC converter and can charge and discharge the energy storage device 61. 【0103】 Figure 10 is a schematic diagram showing the configuration of the second DC / DC converter. 【0104】 In Figure 10, the second DC / DC converter 67 is composed of an upper and lower arm (half-bridge circuit) 671 made up of two switching elements Q5 and Q6, a choke coil 672, capacitors 673 and 674, and a drive control device 675. 【0105】 The drive control device 675 outputs a drive voltage for each element based on the control signal CSD2 from the control device 40. Each element is controlled, for example, based on PWM, and the control signal CSD2 is a PWM duty cycle or a PWM signal. Note that other circuit configurations may be used as the second DC / DC converter, as long as it is a DC / DC converter capable of bidirectional operation. 【0106】 Capacitors 673 and 674 are connected to the input and output sides of the second DC / DC converter 67, respectively. In this state, the input voltage of the second DC / DC converter 67 is equal to the voltage VB of the energy storage device 61. Also, when switches 62 and 63 are closed, the output voltage of the second DC / DC converter 67 is equal to the auxiliary voltage VA. In this embodiment, the output voltage (auxiliary voltage VA) of the second DC / DC converter 67 is higher than the input voltage (voltage VB). Therefore, the voltage specifications of the energy storage device 61 and the second DC / DC converter 67 are determined so that the output voltage of the second DC / DC converter 67 to the auxiliary DC line 30 satisfies the voltage specifications of the auxiliary device 31, and so that the energy storage device 61 and voltage VB are lower than the auxiliary voltage VA. 【0107】 When the second DC / DC converter 67 switches each element, a pulse voltage is generated as the chopper voltage VCH, and the current IL in the choke coil 672 increases or decreases. During the ON period of switching element Q6, the chopper voltage VCH is almost 0 (zero), and the current IL increases in the direction of discharge from the energy storage device 61 (direction of the arrow). Also, during the ON period of switching element Q5, the chopper voltage VCH becomes almost equal to the output voltage, and the current IL decreases. At this time, if the capacitance of capacitor 673 is sufficiently large, the charge / discharge current IB in the steady state becomes the DC component (average value) of the current IL. By controlling the polarity and absolute value of the current IL and thus the current IB using PWM, the charge / discharge current of the energy storage device 61 can be controlled. 【0108】 It is also possible to connect the energy storage device 61 to the output side of the second DC / DC converter 67 and the switch 63 to the input side. In this case, however, it is necessary to determine the voltage specifications of the energy storage device 61 so that the voltage VB is higher than the auxiliary voltage VA. 【0109】 Figure 11 is a functional block diagram that schematically shows the processing contents of the control device according to this embodiment. 【0110】 In Figure 11, the control device 40A is composed of a drive control unit 41, an SoC calculation unit 42, a main motor voltage command generation unit 43, a power generation device control unit 44, a power consumption device control unit 45, a first DC / DC converter control unit 46A, a power storage device switch control unit 47, and a second DC / DC converter control unit 68. 【0111】 The first DC / DC converter control unit 46A generates a control signal CSD1 for the first DC / DC converter 21 based on the main voltage VM and the auxiliary voltage VA, and outputs it to the drive control device 217. 【0112】 The second DC / DC converter control unit 48 generates a control signal CSD2 for the second DC / DC converter 67 based on the remaining capacity SoC, auxiliary voltage VA, current IB, and control signals CSS1 and CSS2 from the energy storage device switch control unit 47, and outputs it to the drive control device 675. 【0113】 Figure 12 is a functional block diagram that schematically shows the processing contents of the first DC / DC converter control unit according to this embodiment. 【0114】 In Figure 12, the first DC / DC converter control unit 46A includes an on / off control unit 464, a voltage control calculation unit 466, and a calculation unit 467. 【0115】 The first DC / DC converter control unit 46A generates a control signal CSD1 for the first DC / DC converter 21 to control the auxiliary voltage VA according to a first command value (first voltage command value VAref1) of the auxiliary voltage VA that is generated internally. 【0116】 The first DC / DC converter control unit 46A first calculates the deviation (VAref1-VA) between the first voltage command value VAref1 (a predetermined voltage V2) and the auxiliary voltage VA in the calculation unit 467, and based on the calculation result, the voltage control calculation unit 466 generates a provisional signal CSD1temp of the control signal CSD1. Specifically, the voltage control calculation unit 466 uses a control law such as PI control to generate (change) the provisional signal CSD1temp in order to reduce the deviation of the auxiliary voltage VA from the first voltage command value VAref1. The voltage V2 set as the first voltage command value VAref1 is set to fall within the operating voltage range of the auxiliary device 31. 【0117】 The ON / OFF control unit 464 controls the ON / OFF state of the first DC / DC converter 21 based on the main motor voltage VM. Specifically, when the main motor voltage VM is greater than or equal to the lower voltage limit VDmin, the first DC / DC converter 21 can convert the voltage of the DC power of the main motor DC line 15 and output it to the auxiliary DC line 30, and outputs the provisional signal CSD1temp as the control signal CSD1. If the main motor voltage VM is less than the lower voltage limit VDmin, the first DC / DC converter 21 does not convert the voltage of the DC power of the main motor DC line 15 (and cannot supply power to the auxiliary DC line 30). In this case, regardless of the PWM duty cycle of the provisional signal CSD1temp, the control signal CSD1 is generated and output so that all switching elements of the first DC / DC converter 21 are turned off. 【0118】 Figure 13 is a schematic functional block diagram showing the second DC / DC converter control unit. 【0119】 In Figure 13, the second DC / DC converter control unit 48 includes a current limit value generation unit 481 and a voltage control system 482. 【0120】 Furthermore, the voltage control system 482 includes a voltage control calculation unit 483, a variable limiter 484, a current control system 485, and a calculation unit 488. 【0121】 The current limit value generation unit 481 generates a lower limit value of the current IB (current limit value IBlim) based on the remaining capacity SoC of the energy storage device 61. Specifically, if the remaining capacity SoC is less than the upper limit value (remaining capacity upper limit value Smax), the current limit value IBlim is set to a predetermined negative value I1. If the remaining capacity SoC is greater than or equal to the remaining capacity upper limit value Smax, the current limit value IBlim is set to 0 (zero). 【0122】 The voltage control system 482 generates a control signal CSD2 for the second DC / DC converter 67 to control the auxiliary voltage VA according to the second command value (second voltage command value VAref2) of the auxiliary voltage VA generated internally, and outputs it to the drive control device 675. 【0123】 The voltage control system 482 first calculates the difference (VAref2-VA) between the auxiliary voltage VA and the second voltage command value VAref2 using the calculation unit 488. Based on this calculation result, the voltage control calculation unit 483 generates the first command value of the current IB (first current command value IBref1). Specifically, the voltage control calculation unit 483 uses control laws such as PI control to change the first current command value IBref1 to reduce the difference between the auxiliary voltage VA and the second voltage command value VAref2. For example, if the auxiliary voltage VA < second voltage command value VAref2, the first current command value IBref1 is increased to increase the discharge current of the energy storage device 61. The voltage V3 set as the second voltage command value VAref2 is set to be lower than the aforementioned voltage V2 and within the operating voltage range of the auxiliary device 31. 【0124】 The variable limiter 484 applies limiter processing to the first current command value IBref1 so that its lower limit becomes IBlim, and generates this as the second command value of current IB (second current command value IBref2). 【0125】 The current control system 485 generates a control signal CSD2 based on the second current command value IBref2, the current IB, and the control signals CSS1 and CSS2, and includes a current control calculation unit 486, an on / off control unit 487, and a calculation unit 489. 【0126】 The current control system 485 first calculates the difference (IBref2-IB) between the second current command value IBref2 and the current IB using the calculation unit 489, and based on this calculation result, the current control calculation unit 486 generates a provisional signal CSD2temp of the control signal CSD2. Specifically, the current control calculation unit 486 uses a control law such as PI control to change the PWM duty cycle of the provisional signal CSD2temp to reduce the difference between the current IB and the second current command value IBref2. The control signal CSD2 and the provisional signal CSD2temp are PWM signals for turning the switching elements of the second DC / DC converter 67 on and off, respectively. 【0127】 The ON / OFF control unit 487 controls the ON / OFF state of the second DC / DC converter 67 based on the control signals CSS1 and CSS2 of switches 62 and 63 of the energy storage device 60. Specifically, when both switches 62 and 63 are closed, that is, when the energy storage device 61 is ready to be charged and discharged, the provisional signal CSD2temp is output as the control signal CSD2. If at least one of switches 62 or 63 is open, the energy storage device 61 cannot be charged or discharged, so the control signal CSD2 is generated and output so that all switching elements of the second DC / DC converter 67 are turned off, regardless of the PWM duty cycle of the provisional signal CSD2temp. 【0128】 The operation of this embodiment, configured as described above, will now be explained. 【0129】 The control device 40 controls the generator 11 so that the main motor voltage VM is lower than the lower voltage limit VDmin when the rotational speed NM is lower than the speed threshold Nth and the remaining capacity SoC is greater than or equal to the remaining capacity threshold Sth. At this time, the first DC / DC converter 21 cannot supply power to the auxiliary DC line 30, so the auxiliary equipment 31 is driven by discharging the energy storage device 61 using the second DC / DC converter 67. The second DC / DC converter 67 is controlled so that the auxiliary voltage VA becomes voltage V3, and the current IB is determined by the power consumption of the auxiliary equipment 31. 【0130】 Furthermore, if the remaining capacity SoC is less than Sth, the control device 40 controls the generator 11 so that the main voltage VM is equal to or greater than the first voltage value V1 (≧VDmin). At this time, the first DC / DC converter 21 operates so that the auxiliary voltage VA becomes voltage V2. Since voltage V2 > voltage V3, the first DC / DC converter 21 can output with priority over the discharge operation of the second DC / DC converter 67, and as a result, the auxiliary voltage VA is controlled to become voltage V2. The second DC / DC converter 67 operates to reduce the auxiliary voltage VA to voltage V3, decreasing the current IB, i.e., increasing the charging current. However, the variable limiter 484 limits the current IB to current I1. The power consumption of the auxiliary equipment 31 and the charging power of the energy storage device 61 are all supplied from the first DC / DC converter 21. However, when the remaining capacity SoC reaches the upper limit Smax, the charging current is limited to 0 (zero). 【0131】 The other configurations are the same as in the first embodiment. 【0132】 In this embodiment configured as described above, the same effects as in the first embodiment can be obtained. 【0133】 Furthermore, in this embodiment, since a second DC / DC converter 67 is connected between the auxiliary device 31 and the energy storage device 61, it is no longer necessary to determine the voltage specifications of the energy storage device 61 so that the voltage VB falls within the operating voltage range of the auxiliary device 31, thus increasing the degree of freedom when determining the voltage specifications of the energy storage device 61. 【0134】 Furthermore, even if the voltage VB changes due to the remaining capacity SoC, the auxiliary voltage VA can be controlled to voltage V2 or voltage V3 by the first DC / DC converter 21 or the second DC / DC converter 67, respectively. Therefore, even if the remaining capacity SoC of the energy storage device 61 is varied over a wide range, the auxiliary equipment 31 can be driven stably. 【0135】 <Third Embodiment> A third embodiment of the present invention will be described with reference to Figures 14 to 16. 【0136】 In this embodiment, a second DC / DC converter 67 is placed between the first DC / DC converter 21 and the energy storage device 61 (specifically the switch 62) and the auxiliary equipment 31. In this embodiment, the same reference numerals are used for components similar to those in the first and second embodiments, and their descriptions are omitted as appropriate. 【0137】 Figure 14 is a schematic diagram showing the configuration of the auxiliary power supply device according to this embodiment. 【0138】 In Figure 14, the auxiliary power supply unit 20B comprises a first DC / DC converter 21 and an energy storage device 60B. The energy storage device 60B consists of an energy storage device 61, switches 62 and 63, a resistor 64, a voltage detector 65, a current detector 66, and a second DC / DC converter 67. 【0139】 In the auxiliary power supply unit 20B, the second DC / DC converter 67 of the energy storage device 60B is connected between the first DC / DC converter 21 and the auxiliary DC line 30 (i.e., the auxiliary device 31). That is, the input of the first DC / DC converter 21 is connected to the main DC line 15, and its output is connected to the input of the second DC / DC converter 67 of the energy storage device 60B. The energy storage device 61 is also connected to the input of the second DC / DC converter 67 via switches 62 and 63. At this time, the output voltage of the second DC / DC converter 67 is the auxiliary voltage VA. After switches 62 and 63 are closed, the input voltage of the second DC / DC converter 67 becomes voltage VB. The control signal CSA includes the control signal CSD2 of the second DC / DC converter 67. 【0140】 Note that the second DC / DC converter 67 in this embodiment does not necessarily have to be configured for bidirectional operation. Therefore, the circuit configuration of the second DC / DC converter 67 may be the first DC / DC converter 21 shown in the first embodiment (see Figure 3) or the second DC / DC converter 67 shown in the second embodiment (see Figure 10). However, if the circuit configuration shown for the second DC / DC converter 67 shown in the second embodiment (see Figure 10) is used, and the voltage VB of the energy storage device 61 is set higher than the operating voltage of the auxiliary device 31, then the side to which the capacitor 673 is connected must be the output side (auxiliary device 31 side). 【0141】 Figure 15 is a functional block diagram that schematically shows the processing contents of the control device according to this embodiment. 【0142】 In Figure 15, the control device 40B is composed of a drive control unit 41, an SoC calculation unit 42, a main motor voltage command generation unit 43, a power generation device control unit 44, a power consumption device control unit 45, a first DC / DC converter control unit 46, a power storage device switch control unit 47, and a second DC / DC converter control unit 68B. 【0143】 Figure 16 is a schematic functional block diagram showing the second DC / DC converter control unit according to this embodiment. 【0144】 In Figure 16, the second DC / DC converter control unit 48B includes a voltage control calculation unit 490 and a calculation unit 491. 【0145】 The second DC / DC converter control unit 48B calculates the deviation (VAref2-VA) between the auxiliary voltage VA and the second command value VAref2 in the calculation unit 491, and generates the control signal CSD2 for the second DC / DC converter 67 in the voltage control calculation unit 490 based on the calculation result. Specifically, the voltage control calculation unit 490 uses a control law such as PI control to change the control signal CSD2 to reduce the deviation between the auxiliary voltage VA and the second voltage command value VAref2. In this embodiment, the value of the second voltage command value VAref2 is set to voltage V3 as in Figure 13 of the second embodiment, but it may also be set to voltage V2 as in Figure 12. 【0146】 The operation of this embodiment, configured as described above, will now be explained. 【0147】 The control device 40B controls the generator 11 so that the main motor voltage VM is lower than the lower voltage limit VDmin when the rotational speed NM of the travel motor 10 is lower than the speed threshold Nth and the remaining capacity SoC is greater than or equal to the remaining capacity threshold Sth. At this time, the first DC / DC converter 21 cannot supply power to the auxiliary DC line 30 side (i.e., the input of the second DC / DC converter 67), so the auxiliary equipment 31 is driven by discharging the energy storage device 61 using the second DC / DC converter 67. The second DC / DC converter 67 is controlled so that the auxiliary voltage VA becomes voltage V3, and the current IB is determined by the power consumption of the auxiliary equipment 31. 【0148】 Furthermore, if the remaining capacity SoC is less than the remaining capacity threshold Sth, the control device 40B controls the power generator 11 so that the main voltage VM is equal to or greater than the first voltage value V1 (≧VDmin). At this time, the first DC / DC converter 21 operates to set the current IB to the current value I1 and charges the energy storage device 61. The power consumption of the auxiliary equipment 31 and the charging power of the energy storage device 61 are all supplied from the first DC / DC converter 21. However, when the remaining capacity SoC of the energy storage device 61 reaches the upper limit Smax, the charging current is limited to 0 (zero). 【0149】 The other configurations are the same as those in the first and second embodiments. 【0150】 In this embodiment configured as described above, the same effects as those of the first and second embodiments can be obtained. 【0151】 Furthermore, in this embodiment, a first DC / DC converter 21 and a second DC / DC converter 67 are connected in series between the main DC line 15 and the auxiliary DC line 30. In the second embodiment, an isolated DC / DC converter with a transformer was used as the first DC / DC converter 21, and a non-isolated DC / DC converter without a transformer was used as the second DC / DC converter 67. However, in this embodiment, a non-isolated DC / DC converter can be applied to the first DC / DC converter 21 and an isolated DC / DC converter can be applied to the second DC / DC converter 67, thereby providing isolation between the main DC line 15 and the auxiliary DC line 30. In particular, in this embodiment, since it is assumed that the main voltage VM will be varied over a wide range, these configurations can reduce the fluctuations in the input voltage and output voltage of the isolated DC / DC converter, and as a result, the isolated DC / DC converter can be miniaturized. 【0152】 <Note> It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications and combinations that do not depart from the spirit of the invention. Furthermore, the present invention is not limited to having all the configurations described in the embodiments described above, and includes configurations in which some of the configurations are omitted. In addition, some or all of the above configurations, functions, etc. may be realized by designing, for example, an integrated circuit. Furthermore, each of the above configurations, functions, etc. may be realized in software by having a processor interpret and execute a program that realizes each function. [Explanation of symbols] 【0153】 1...Body frame, 2L, 2R...Driven wheels (front wheels), 3L, 3R...Drive wheels (rear wheels), 4...Driver's cab, 5...Cargo bed (vessel), 5a...Pin coupling, 6...Hoist cylinder, 7...Grid box, 8...Control cabinet, 9...Fuel tank, 10L, 10R...Traction motor, 11...Generator, 12...Engine, 13...Main generator, 14...Rectifier circuit, 15...Main DC line, 16...Inverter, 17...Power consumption device, 18...Voltage detector, 19...Capacitor, 20, 20A, 20B...Auxiliary power supply unit, 21...First DC / DC converter, 30...Auxiliary DC line, 31...Auxiliary equipment, 32...Voltage detector, 33...Con Densa, 40, 40A, 40B... Control device, 41... Drive control unit, 42... SoC calculation unit, 43... Main engine voltage command generation unit, 44... Power generation device control unit, 45... Power consumption device control unit, 46, 46A... First DC / DC converter control unit, 47... Energy storage device switch control unit, 48, 48B... Second DC / DC converter control unit, 50... Current detector, 51... Speed ​​detector, 60, 60A, 60B... Energy storage device, 61... Energy storage device, 62, 63... Switch, 64... Resistor, 65... Voltage detector, 66... ​​Current detector, 67... Second DC / DC converter, 68, 68B... Second DC / DC converter control unit, 100... Electric drive dump truck

Claims

[Claim 1] Power generation equipment, The main DC line to which DC power generated by the aforementioned power generator is supplied, The driving motor and An inverter that drives the travel motor with DC power supplied to the main DC line, Auxiliary equipment and, An auxiliary DC line that supplies DC power to drive the aforementioned auxiliary equipment, An auxiliary power supply unit having a DC / DC converter capable of converting the DC voltage of the main DC line and supplying it to the auxiliary DC line when the DC voltage of the main DC line is above a predetermined voltage threshold, and a power storage device for storing power that can be supplied to the auxiliary DC line, The system comprises a power generation device and a control device for controlling the auxiliary power supply device, The electric work vehicle is characterized in that the control device controls the power generator and the auxiliary power supply device according to the rotational speed of the travel motor and the remaining charge of the power storage device. [Claim 2] In the electric work vehicle according to claim 1, The control device is When the rotational speed of the drive motor is lower than a predetermined speed threshold, and the remaining charge of the energy storage device is equal to or greater than a predetermined remaining charge threshold, the power generation device is controlled so that the voltage of the main DC line is lower than the voltage threshold. An electric work vehicle characterized in that, when the rotational speed of the travel motor is lower than a predetermined speed threshold and the remaining charge of the energy storage device is less than the remaining charge threshold, the generator is controlled so that the voltage of the main DC line becomes higher than the voltage threshold, while the auxiliary power supply device is controlled to charge the energy storage device. [Claim 3] In the electric work vehicle according to claim 1, The control device is A main motor voltage command table defines the relationship between the rotational speed of the travel motor and a first provisional voltage command value generated as a provisional value of the command value for controlling the power generation device, The system includes a main engine voltage command limiting table that defines the relationship between the first provisional voltage command value generated according to the main engine voltage command table and a second provisional voltage command value in which a voltage lower limit value is set for the first provisional voltage command value, An electric work vehicle characterized in that, when the remaining charge of the energy storage device is equal to or greater than a predetermined remaining charge threshold, the power generation device is controlled according to the first provisional voltage command value, and when the remaining charge of the energy storage device is less than the remaining charge threshold, the power generation device is controlled according to the second provisional voltage command value. [Claim 4] In the electric work vehicle according to claim 3, The main motor voltage command table is configured such that when the rotational speed of the travel motor is lower than a predetermined speed threshold, the first provisional voltage command value becomes lower than the voltage lower limit, and when the rotational speed is higher than the speed threshold, the first provisional voltage command value becomes higher than the voltage lower limit. The electric work vehicle is characterized in that the main motor voltage command limiting table is defined such that the lower voltage limit is greater than the voltage threshold. [Claim 5] In the electric work vehicle according to claim 2, The control device is If the DC voltage of the main DC line is above a predetermined voltage threshold, and the remaining charge of the energy storage device is less than a predetermined upper limit of remaining capacity, A current target value is set, which is the target value of the current supplied from the auxiliary DC line to the energy storage device in order to charge the energy storage device. An electric work vehicle characterized by controlling the DC / DC converter so that the deviation between the current value supplied to the energy storage device and the current target value becomes small. [Claim 6] In the electric work vehicle according to claim 2, An electric work vehicle characterized in that, when the DC voltage of the main DC line is less than a predetermined voltage threshold, the DC / DC converter stops converting the DC voltage of the main DC line and supplying it to the auxiliary DC line. [Claim 7] In the electric work vehicle according to claim 2, The aforementioned auxiliary power supply device is In addition to the first DC / DC converter, which is a DC / DC converter capable of converting the DC voltage of the main engine DC line and supplying it to the auxiliary engine DC line when the DC voltage of the main engine DC line is above a predetermined voltage threshold, The system further includes a second DC / DC converter capable of converting and supplying DC voltage between the energy storage device and the auxiliary DC line. The control device is A first DC / DC converter control unit generates a control signal for the first DC / DC converter based on the voltage of the main DC line and the voltage of the auxiliary DC line, The system includes a second DC / DC converter control unit that generates a control signal for the second DC / DC converter based on the remaining charge of the energy storage device and the discharge current, The first DC / DC converter control unit generates a control signal for the first DC / DC converter such that the deviation between the voltage of the auxiliary DC line and a predetermined first voltage command value is reduced when the voltage of the main DC line is equal to or greater than the voltage threshold. The second DC / DC converter control unit is, If the remaining charge of the energy storage device is less than a predetermined upper limit of the remaining charge, a current limit value generation unit sets the current value in the charging direction of the energy storage device as a current limit value, The voltage control system includes a voltage control calculation unit that increases a predetermined first current command value when the voltage of the auxiliary DC line is lower than a predetermined second voltage command value, a variable limiter that applies limiter processing to the first current command value to generate a second current command value so that the first current command value is equal to or greater than the current limit value, and a current control system that controls the charging and discharging of the energy storage device. The current control system generates a control signal for the second DC / DC converter such that the deviation between the current value in the charging direction of the energy storage device and the second current command value becomes small. An electric work vehicle characterized in that the second voltage command value is set lower than the first voltage command value. [Claim 8] In the electric work vehicle according to claim 2, The aforementioned auxiliary power supply device is In addition to the first DC / DC converter, which is a DC / DC converter capable of converting the DC voltage of the main engine DC line and supplying it to the auxiliary engine DC line when the DC voltage of the main engine DC line is above a predetermined voltage threshold, The system further includes a second DC / DC converter provided on the auxiliary DC line, which is capable of converting the DC voltage of the first DC / DC converter and the energy storage device and supplying it to the auxiliary device. The control device is A first DC / DC converter control unit generates a control signal for the first DC / DC converter based on the remaining charge of the energy storage device, the voltage of the main DC line, and the current value in the discharge direction of the energy storage device. The system includes a second DC / DC converter control unit that generates a control signal for the second DC / DC converter based on the voltage of the auxiliary DC line, The first DC / DC converter control unit is, If the remaining charge of the energy storage device is less than a predetermined upper limit of the remaining charge, a current command generation unit sets a current value in the charging direction of the energy storage device as the current command value, The system includes a current control system that generates a control signal for the first DC / DC converter such that the deviation between the charging current value of the energy storage device and the current command value is reduced when the voltage of the main DC line is equal to or greater than the voltage threshold, The electric work vehicle is characterized in that the second DC / DC converter control unit generates a control signal for the second DC / DC converter such that the deviation between the voltage of the auxiliary DC line and a predetermined voltage command value is reduced.

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