Electric work vehicle

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 technology]

[0002] In recent years, against the backdrop of the depletion of fossil fuels and the worsening of global environmental problems, electric vehicles that use electric energy, such as hybrid vehicles and electric vehicles, have become increasingly popular. For example, various electrically driven work vehicles are used at mining sites, and large electric work vehicles, such as electrically driven dump trucks, are also used as work vehicles for transportation.

[0003] A technology relating to such power supply control of an electric vehicle is known, for example, from Patent Document 1. Patent Document 1 discloses a power supply system for a vehicle including a main battery for storing power for driving, an auxiliary battery for storing power to be supplied to auxiliary devices of the vehicle, and a converter capable of performing bidirectional power conversion between the main battery and the auxiliary battery, the power supply system for the vehicle including a controller for controlling the main battery, the auxiliary battery, and the converter, the controller being configured to supply power from the main battery to the auxiliary battery when a predetermined condition is satisfied, determining whether the power supply system for the vehicle is off, and when the power supply system for the vehicle is off, further determining whether the remaining charge of the main battery is equal to or less than a predetermined value, and configured to prohibit operation of the auxiliary device when the remaining charge of the main battery is equal to or less than the predetermined value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-43689 A Summary of the Invention [Problem to be solved by the invention]

[0005] Electrically driven dump trucks are equipped with an electric drive system that uses an inverter to convert the power generated by the main engine generator connected to the engine to drive the traction motor connected to the main engine DC line, and also converts the power of the main engine DC line using a DC / DC converter and supplies it to the auxiliary equipment DC line to drive 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 dump trucks used in mines, the power handled by the main DC line tends to become higher voltage as the capacity of the electric drive system increases. On the other hand, when the electric work vehicle is stopped or traveling at a low speed, a relatively low voltage may be applied to the traveling motor. Therefore, it is possible 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 value when the vehicle is stopped or traveling at a low speed, it is possible to reduce losses and noise generated in the circuit on the main DC line side.

[0007] However, the larger the circuit size of a DC / DC converter that converts the voltage of the power supplied from the main DC line to the auxiliary DC line, the wider the range of input voltages that the main DC line can support. In other words, making a DC / DC converter compatible with a wide range of input voltages from high to low voltages leads to an increase in the size of the DC / DC converter.

[0008] On the other hand, it is possible to reduce the size of the DC / DC converter by narrowing the range of the input voltage that the DC / DC converter can handle. However, when the voltage on the main DC line side becomes lower than the range of the input voltage that the DC / DC converter can handle, such as when the vehicle is stopped or running at low speed, the DC / DC converter may become inoperable, and may not be able to supply power to the auxiliary equipment.

[0009] The present invention has been made in consideration of the above, and has an object to provide an electric work vehicle that can miniaturize the DC / DC converter, ensure a stable power supply to the auxiliary equipment, and reduce losses and noise that occur when the vehicle is stopped or traveling at low speeds. [Means for solving the problem]

[0010] The present application includes a number of means for solving the above-mentioned problems, and one example thereof includes an auxiliary power supply device having a power generation device, a main engine DC line to which DC power generated by the power generation device is supplied, a traveling motor, an inverter for driving the traveling motor with the DC power supplied to the main engine DC line, an auxiliary device, an auxiliary DC line for supplying DC power to drive the auxiliary device, a DC / DC converter capable of converting the DC voltage of the main engine DC line and supplying it to the auxiliary DC line when the DC voltage of the main engine DC line is equal to or higher than a predetermined voltage threshold, and a power storage device for storing power that can be supplied to the auxiliary DC line, and a control device for controlling the power generation device and the auxiliary power supply device, and the control device controls the power generation device and the auxiliary power supply device in accordance with the rotational speed of the traveling motor and the remaining amount of power stored in the power storage device. Effect of the Invention

[0011] According to the present invention, it is possible to reduce the size of a DC / DC converter, ensure a stable supply of power to auxiliary devices, and reduce loss and noise that occur when the vehicle is stopped or traveling at low speeds. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram illustrating an electric drive system of an electrically driven dump truck. [Diagram 2] FIG. 2 is a diagram illustrating a schematic configuration of an auxiliary power supply device. [Diagram 3] FIG. 2 is a diagram illustrating a schematic configuration of a first DC / DC converter. [Figure 4] FIG. 2 is a functional block diagram illustrating the process of a control device. [Diagram 5] FIG. 2 is a functional block diagram illustrating the process of a main engine voltage command generating unit. [Figure 6] 5 is a flowchart showing the process of a main engine voltage command generating unit; [Figure 7] 3 is a functional block diagram illustrating the process of a power generation device control unit and a power consumption device control unit. FIG. [Figure 8] 4 is a functional block diagram illustrating the outline of processing performed by a first DC / DC converter control unit. FIG. [Figure 9] FIG. 13 is a diagram illustrating a schematic configuration of an auxiliary power supply device according to a second embodiment. [Figure 10] FIG. 4 is a diagram illustrating a schematic configuration of a second DC / DC converter. [Figure 11] FIG. 11 is a functional block diagram illustrating the process of a control device according to a second embodiment. [Figure 12] FIG. 11 is a functional block diagram illustrating an outline of the processing performed by a first DC / DC converter control unit according to a second embodiment. [Figure 13] FIG. 4 is a functional block diagram illustrating a second DC / DC converter control unit. [Figure 14] FIG. 13 is a diagram illustrating a schematic configuration of an auxiliary power supply device according to a third embodiment. [Figure 15] FIG. 11 is a functional block diagram illustrating the process of a control device according to a third embodiment. [Figure 16] FIG. 13 is a functional block diagram illustrating a second DC / DC converter control unit according to a third embodiment. [Figure 17] 1 is a side view showing a schematic external appearance of an electrically driven dump truck shown as an example of an electric work vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an electrically driven dump truck will be shown as an example of an electric work vehicle, but the present invention can also be applied to other electrically driven work vehicles such as an electrically driven wheel loader.

[0014] <First embodiment> A first embodiment of the present invention will be described with reference to FIGS. 1 to 8 and 17. FIG.

[0015] Fig. 17 is a side view showing a schematic appearance of an electrically driven dump truck according to this embodiment. Fig. 1 is a diagram showing an electric drive system of the electrically driven dump truck. In Fig. 17, only one of a pair of left and right components such as a driven wheel, a driving wheel, and a traveling motor is shown and reference numerals are given, and the other components are not shown but are indicated by reference numerals in parentheses in the drawing.

[0016] In FIG. 17, the electrically driven dump truck 100 includes a vehicle body frame 1 that extends in the front-rear direction to form a support structure, a loading platform (vessel) 5 that is disposed on top of the vehicle body frame 1 so as to extend in the front-rear direction and has its rear end lower part tiltably attached to the vehicle body frame 1 via a pin connection part 5a, a pair of driven wheels (front wheels) 2L, 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, 3R provided on the left and right of the lower rear side of the vehicle body, and a load-bearing wheel (load-bearing wheel) 4L, 4R provided on the upper front side of the vehicle body frame 1. The vehicle is roughly composed of a driver's cab 4 mounted on the vehicle body frame 1, a fuel tank 9 provided below the vehicle body frame 1, an engine 12 (see FIG. 1) arranged on the vehicle body frame 1 and driven by fuel supplied from the fuel tank 9, and an electric drive system (see FIG. 1) having a main engine generator 13 (see FIG. 1) connected to and driven by the engine 12, and supplying electric power generated and output by the main engine generator 13 to the travel motors 10L, 10R that drive the wheels (drive wheels 3L, 3R), the auxiliary equipment 31, etc.

[0017] The traveling motors 10L, 10R are housed in the rotating shafts of the drive wheels 3L, 3R together with reduction gears (not shown), and are driven by power supplied via an inverter 16. Note that in Fig. 1, for simplicity of illustration, some of the reference numerals have been omitted, and the left and right traveling motors 10L, 10R are collectively simply indicated by the reference numeral "10."

[0018] The vehicle body frame 1 and the loading platform 5 are connected via a hoist cylinder 6. By extending and contracting the hoist cylinder 6, the loading platform 5 is rotated around the pin connection portion 5a, and the loading platform 5 is raised and lowered relative to the vehicle body frame 1.

[0019] A deck, steps, etc. on which the operator can walk are attached to the vehicle body frame 1, and the operator can move to the cab 4 via these decks and steps. An accelerator pedal, brake pedal, hoist pedal, steering wheel, etc. (not shown) are installed inside the cab 4. The operator controls the acceleration and braking force of the electrically driven dump truck 100 by the amount of depression of the accelerator pedal and brake pedal in the cab 4, performs steering operation by hydraulic drive by turning the steering wheel left and right, and performs dumping operation of the loading platform 5 by hydraulic drive by depressing the hoist pedal.

[0020] A control cabinet 8 housing various electric power devices and a plurality of grid boxes 7 for dissipating surplus energy as heat by means of power consumption devices 17 (see FIG. 1) are mounted behind the cab 4. Although not shown in FIG. 17, the engine 12 and main engine generator 13 shown in FIG. 1 are mounted on the body frame 1 located between the left and right front wheels 2L, 2R.

[0021] In FIG. 1, the electric drive system of the electrically driven dump truck 100 includes a main engine generator 13 connected to an engine 12, a rectifier circuit 14 connected to the main engine generator 13 and rectifying the output of the main engine generator 13 to output the rectified output as DC power to a main engine DC line 15, an inverter 16 for a traveling motor connected between the main engine DC line 15 and the traveling motors 10L, 10R, a power consumption device 17 capable of consuming the power of the main engine DC line 15, an auxiliary device 31, an auxiliary DC line 30 supplying DC power for driving the auxiliary device 31, an auxiliary power supply device 20 having a DC / DC converter capable of converting the voltage (DC voltage) of the DC power of the main engine DC line 15 and supplying the converted voltage to the auxiliary DC line 30 when the voltage (DC voltage) of the DC power of the main engine DC line 15 is equal to or higher than a predetermined voltage threshold (described later), and a control device 40 for controlling the operation of the main engine generator 13, the auxiliary power supply device 20, and the like.

[0022] The power generation device 11 is composed of an engine 12, a main engine generator 13, and a rectifier circuit 14, and supplies electric power to a main engine DC line 15 to generate a main engine voltage VM on the main engine DC line 15.

[0023] A DC input of an inverter 16 for the traveling motor is connected to the main engine DC line 15. An AC output of the inverter 16 is connected to the traveling motor 10.

[0024] A current detector 50 is provided between the inverter 16 and the traveling motor 10, and detects the current IM supplied from the inverter 16 to the traveling motor 10, and transmits the detected value to the control device 40. The traveling motor 10 is also provided with a speed detector 51, and detects the rotation speed NM of the traveling motor 10, and transmits the detected value to the control device 40. Note that, although one current detector 50 and one detection signal line are shown in FIG. 1 for detecting the current IM, it is also possible to configure the detector to detect at least two phases of the three-phase AC current flowing through the traveling motor 10. Also, when there are multiple traveling motors, it is also possible to configure the detector to detect the current and rotation speed of all of the traveling motors.

[0025] In addition to the inverter 16, a power consumption device 17 for consuming regenerative power from the traction motor 10 is connected to the main DC line 15. The power consumption device 17 is made up of a chopper circuit consisting of 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 engine DC line 15, which detects a main engine voltage VM, which is a DC voltage generated in the main engine DC line 15, and transmits the detected value to the control device 40. In addition, a capacitor 19 is provided in the main engine DC line 15 for smoothing the main engine voltage VM.

[0027] The input of the auxiliary power supply device 20 is connected to the main DC line 15 , and the output is connected to the auxiliary DC line 30 .

[0028] The auxiliary device 31 is, for example, an inverter and compressor motor system for an air conditioner, an inverter and blower motor system for cooling equipment, etc. In Fig. 1 of this embodiment, for the sake of simplicity of explanation, these loads are integrated into one equivalent impedance and shown as the auxiliary device 31.

[0029] A voltage detector 32 is provided on the auxiliary DC line 30, which detects an auxiliary voltage VA, which is a DC voltage generated on the auxiliary DC line 30, and transmits the detected value to the control device 40. In addition, a capacitor 33 is provided on the auxiliary DC line 30 to smooth the auxiliary voltage VA.

[0030] Although not shown in Fig. 1 and the above description, a discharge resistor for a capacitor, a surge protector such as a varistor or an arrester, etc. may be connected to the main DC line 15 and the auxiliary DC line 30. When connecting each device to the main DC line 15 and the auxiliary DC line 30, fuses, reactors, switches (electromagnetic contactors, circuit breakers, etc.) may be inserted.

[0031] In addition, IGBTs (Insulated Gate Bipolar Transistors) are shown as examples of switching elements of inverter 16 and power consumption device 17, and a circuit symbol of an IGBT is shown in Fig. 1, but the present invention is not limited to this. 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] 1 shows a circuit symbol for a diode as the rectifier circuit 14, the present invention 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 description, the main generator 13 is a winding excitation type synchronous generator having an excitation device as an actuator, but as described above, an AC / DC converter is used as the rectifier circuit 14, and other types of generators such as a permanent magnet synchronous generator may also be used.

[0034] The control device 40 receives the detection value (main engine voltage VM) of the voltage detector 18, the detection value (auxiliary voltage VA) of the voltage detector 32, the detection value (current IM) of the current detector 50, and the detection value (rotation speed NM) of the speed detector 51. In addition, a vehicle information signal DSV is input to the control device 40 from an external higher-level control system. Although the vehicle information signal DSV is shown as a single signal line in FIG. 1, the vehicle information signal DSV includes a plurality of pieces of information such as vehicle body speed information and operator operation input information (accelerator pedal operation amount DSACL, brake pedal operation amount DSBRK, etc.). In addition, a detection signal DSA is input to the control device 40 from the auxiliary power supply device 20.

[0035] The control device 40 generates and transmits control signals for each device based on the detection values ​​(detection signals VM, VA, IM, NM) from the detectors 18, 32, 50, 51 and the signals DSV and DSA, thereby controlling the voltage and power flow in the electric drive system. 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 a 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. Note that, although these control signals and the like are each indicated by a single arrow in FIG. 1, each signal may include multiple pieces of information.

[0036] The control device 40 may be realized in any manner, for example, by mounting devices such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), a microcomputer, and an FPGA (Field-Programmable Gate Array) on a substrate to realize the control device 40 as an electronic circuit. Since the control device 40 includes multiple arithmetic blocks, each arithmetic block may be mounted on a separate substrate or device. Also, one arithmetic block may be divided and mounted on multiple substrates or devices.

[0037] FIG. 2 is a diagram showing a schematic configuration of the auxiliary power supply device.

[0038] In FIG. 2, the auxiliary power supply device 20 includes a first DC / DC converter 21 and a power storage device 60.

[0039] An input section of the first DC / DC converter 21 is connected to the main DC line 15, and an output section is connected to the auxiliary DC line 30. In addition, the power storage device 60 is connected to the auxiliary DC line 30.

[0040] The electricity storage device 60 is made up of an electricity storage device 61 , switches 62 and 63 , a resistor 64 , a voltage detector 65 , and a current detector 66 .

[0041] The power storage device 61 is, for example, 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] The switches 62, 63 are arranged in series between the power storage device 61 and the auxiliary DC line 30, and a resistor 64 is connected in parallel to the switch 63. The switch 62 opens and closes between the power storage device 61 and the auxiliary DC line 30. The parallel combination of the switch 63 and the resistor 64 functions as an initial charging circuit for the capacitor 33 of the auxiliary DC line 30. When the switches 62, 63 are in an open state, first, when the switch 62 is closed, the power from the power storage device 61 charges the capacitor 33 via the resistor 64, and the auxiliary voltage VA increases to the same level as the voltage VB, which is the DC voltage of the input / output section of the power storage device 61. When the switch 63 is then closed, the resistor 64 is bypassed. These switch operations are performed after the start of the electrically driven dump truck 100, which is an electric work vehicle. Since the auxiliary voltage VA becomes equal to the voltage VB of the power storage device 61, the voltage specification of the power storage device 61 is determined so that the voltage VB is within the range of the operating voltage of the auxiliary device 31. When connecting the power storage device 60 to the auxiliary DC line 30, a fuse or a circuit breaker may be inserted.

[0043] The switches 62 and 63 will be described by taking, for example, an electromagnetic contactor or an electromagnetic switch as an example, but coils, drive circuits, etc. will not be shown. The switches 62 and 63 are controlled to be opened and closed by control signals CSS1 and CSS2, respectively. The control signals CSS1 and CSS2 sent to the switches 62 and 63, and a control signal CSD1 (described later) sent to the first DC / DC converter 21 are included in the control signal CSA sent from the control device 40 to the auxiliary power supply device 20.

[0044] A voltage detector 65 and a current detector 66 are provided between the power storage device 61 and the auxiliary DC line 30 (i.e., the input / output section of the power storage device 61), which detect a voltage VB, which is the DC voltage of the input / output section of the power storage device 61, and a charge / discharge current IB, which is the DC current exchanged between the power storage device 61 and the auxiliary DC line 30, and transmit these detected values ​​together to the control device 40 as a detection signal DSA.

[0045] As described above, the auxiliary power supply 20 can drive the auxiliary device 31 and charge the power storage device 61 using the output power from the first DC / DC converter 21. The auxiliary power supply 20 can also supply power to the auxiliary device 31 by discharging the power storage device 61.

[0046] FIG. 3 is a diagram illustrating a schematic configuration of the first DC / DC converter.

[0047] In Figure 3, the first DC / DC converter 21 converts the voltage of the DC power on 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 on the main DC line 15 (main voltage VM) is equal to or higher than a predetermined voltage threshold (described later), and is roughly composed of a full-bridge inverter 211 composed of four switching elements Q1, Q2, Q3, Q4, a transformer 212, a full-bridge rectifier circuit 213 composed of four diodes D1, D2, D3, D4, a choke coil 214, capacitors 215, 216, and a drive control device 217.

[0048] The full-bridge inverter 211 converts the main voltage VM input from the main DC line 15 into an AC voltage VTR and applies it to a primary winding (main DC line 15 side) of the transformer 212. The transformer 212 transforms the voltage applied to the primary winding to generate an AC voltage in the secondary winding (auxiliary DC line 30 side) while insulating between the input and output of the first DC / DC converter 21 (between the main DC line 15 and the auxiliary DC line 30). The AC voltage generated in the secondary winding of the transformer 212 is converted into a DC voltage by a full-bridge rectifier circuit 213 and output to the auxiliary DC line 30 as an auxiliary voltage VA via a filter circuit composed of a choke coil 214 and a capacitor 216. That is, the first DC / DC converter 21 can insulate the main DC line 15 from the auxiliary DC line 30 by using the transformer 212. Furthermore, even if 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 use of the transformer 212 makes it possible to reduce the current flowing through the primary side circuit.

[0049] The drive control device 217 outputs a drive voltage for each element constituting the first DC / DC converter 21, based on a control signal CSD1 input from the control device 40. For example, when the first DC / DC converter 21 is configured to control the on / off of each element based on pulse width modulation (PWM), the control signal CSD1 is a PWM duty or a PWM signal.

[0050] In Fig. 3, an example is described in which an IGBT is used as a switching element, but this is not limiting, and other types of switching elements such as a MOSFET may be used. In addition to the above configuration, a configuration including switches, protective components such as a fuse and a surge protector, and a noise filter may be used. In Fig. 3 and the above-mentioned Fig. 2, the control signal CSD1 is shown with a single arrow, but the control signal CSD1 may include multiple pieces of information. For example, when the first DC / DC converter 21 includes multiple switching elements, the control signal CSD1 is configured as a collection of control signals for each element.

[0051] Here, the variable range of the main voltage VM of the main DC line 15 and the input voltage range of the first DC / DC converter will be described.

[0052] In the electric drive system according to this embodiment shown in Fig. 1, the main engine voltage VM of the main engine DC line 15 is controlled by the power generation device 11 or the power consumption device 17. When the traveling motor 10 is stopped or in power running, the main engine voltage VM is controlled by the power generation device 11. Also, when the traveling motor 10 is in regeneration, the output of the power generation device 11 is not required, and the main engine voltage VM is controlled by the power consumption device 17.

[0053] As described above, when the electrically driven dump truck 100 is a large electric work vehicle such as a mining dump truck, the main engine voltage VM tends to be high. On the other hand, even in the case of a large electric work vehicle, the voltage that the inverter 16 should apply to the traveling motor 10 becomes relatively low when the vehicle is stopped or traveling at a low speed.

[0054] Therefore, in this embodiment, the maximum and minimum values ​​of the main engine voltage VM are set to VMmax and VMmin, respectively, and the main engine voltage VM is changed according to the speed of the electrically-driven dump truck 100 (here, the rotational speed NM of the traveling motor 10), thereby controlling the main engine voltage VM to a low value when stopped or traveling at low speeds, thereby reducing losses and noise generated in the main engine circuits such as the inverter 16 and the power consumption device 17.

[0055] On the other hand, when the main voltage VM is changed, the first DC / DC converter 21 needs to have a wide input voltage specification that can accommodate the change range of the main voltage VM. Moreover, the wider the input voltage specification range, the larger the first DC / DC converter 21 needs to be. Specifically, since the amplitude of the current flowing through the primary circuit of the transformer 212 increases, it is necessary to enlarge the transformer 212, the full-bridge inverter 211, and the cooling system (not shown) so as to withstand this current. Furthermore, when the main voltage VM is low, the input current of the first DC / DC converter 21 increases, so it is necessary to enlarge the switches and fuses (not shown) of the input section.

[0056] In this embodiment, in order to avoid an increase in size of the first DC / DC converter 21, the range in which the first DC / DC converter 21 performs the power conversion operation is limited to the case where the main voltage VM is equal to or higher than a predetermined voltage lower limit value (threshold voltage) VDmin, thereby reducing the size of the first DC / DC converter 21. At this time, the voltage lower limit value (threshold voltage) VDmin is set higher than the minimum value VMmin of the main voltage VM, and the voltage lower limit value VDmin is then set higher, thereby making it possible to further reduce the size of the first DC / DC converter 21. Also, when the main voltage VM is within 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 voltage lower limit value VDmin>main voltage VM≧minimum value VMmin), power is supplied from the power storage device 61 to the auxiliary device 31 as necessary. The above-mentioned control of the electric drive system according to this embodiment is realized by the control device 40.

[0057] FIG. 4 is a functional block diagram showing the outline of 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 engine 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 storage device switch control unit 47.

[0059] The drive control unit 41 generates control signals CSE, CSI according to operation input information such as the accelerator pedal operation amount DSACL and the brake pedal operation amount DSBRK contained in the vehicle information signal DSV from the higher-level control system, and outputs them to the engine 12 and the inverter 16, respectively. This allows the vehicle to be appropriately accelerated or decelerated according to the accelerator pedal operation amount DSACL and the brake pedal operation amount DSBRK.

[0060] The SoC calculation unit 42 calculates the remaining capacity SoC (State of Charge) of the power storage device 61 and outputs it to the main voltage command generation unit 43 and the first DC / DC converter control unit 46. The remaining capacity SoC can be calculated using a method that utilizes the relationship between the voltage value VB and the remaining capacity SoC of the power storage device 61, or a method that determines the amount of change in the remaining capacity SoC from the integral value of the current value IB of the power 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 generating unit 43 generates a command value (main engine DC voltage command value VMref) related to the main engine voltage Vm in accordance with the rotation speed NM and remaining capacity SoC of the traveling motor 10, and outputs the command value to the power generation device control unit 44 and the power consumption device control unit 45. Note that in FIG. 4, the rotation speed NM of the traveling motor 10 detected by the speed detector 51 is illustrated as an example of the speed input to the main engine voltage command generating unit 43, but this is not limiting, and if the speed of the traveling motor 10 or the electrically driven dump truck 100 can be detected or estimated by means other than the speed detector 51, these values ​​may be input to the main engine voltage command generating unit 43 instead of the rotation speed NM, and the main engine DC voltage command value VMref may be calculated.

[0062] The power generation device control unit 44 performs calculations so that the main engine voltage VM coincides with the main engine DC voltage command value VMref, generates a control signal VFref which is an operation amount for the power generation device 11, and outputs it to the main engine generator 13 of the power generation device 11.

[0063] The power consuming device control unit 45, like the power generating device control unit 44, performs calculations to control the main machine voltage VM based on the main machine DC voltage command value VMref, generates a control signal CSR for the power consuming device 17, and outputs it to the drive control device 174. However, as will be described later, the command value for the main machine voltage VM is changed from the main machine 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 capacity SoC, the current value IB, and the main engine voltage VM, and outputs the signal to the drive control device 217. Specifically, it generates a command value IBref for the current value IB based on the remaining capacity SoC, performs a current control calculation for controlling the current value IB in accordance with the command value IBref, and performs on-off control based on the main engine voltage VM, and as a result, generates the control signal CSD1.

[0065] The power 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 power storage device 61, and outputs the control signals CSS1 and CSS2 to the switches 62 and 63, respectively. Specifically, when the power storage device switch control unit 47 detects the start of the electrically driven dump truck 100 based on the vehicle information signal DSV, it generates (changes) the control signal CSS1 to close the switch 62. Thereafter, when it detects that the auxiliary voltage VA has increased to substantially the same level as the voltage VB, it generates (changes) the control signal CSS2 to close the switch 63. Note that the power storage device switch control unit 47 may have a function of generating (changing) the control signal CSS1 to open the switch 62 when it detects an abnormality in the vehicle based on the vehicle information signal DSV.

[0066] Fig. 5 is a functional block diagram showing the outline of the processing contents of the main engine voltage command generating unit, and Fig. 6 is a flowchart showing the processing contents of the main engine voltage command generating unit.

[0067] As shown in FIG. 5, the main engine voltage command generating unit 43 includes a main engine voltage command table 431 , a main engine voltage command limiter 432 , and a main engine voltage command selecting unit 433 .

[0068] The main engine voltage command table 431 is a table in which the relationship between the rotation speed NM of the traveling motor 10 and the first provisional value VMref1 of the main engine DC voltage command value VMref is set. In FIG. 5, the vertical axis of the main engine voltage command table 431 indicates the first provisional value VMref1, and the horizontal axis indicates the rotation speed NM. In the main engine voltage command table 431, the first provisional value VMref1 takes the minimum value VMmin until the rotation speed NM changes from 0 to a predetermined rotation speed N1, and when the rotation speed NM exceeds the rotation speed N1, the first provisional value VMref1 also increases with the increase in the rotation speed NM, and when the rotation speed NM becomes equal to or higher than the predetermined rotation speed N2, the first provisional value VMref1 takes the maximum value VMmax. Here, when the rotation speed NM is the rotation speed threshold value Nth, the first provisional value VMref1 takes the voltage lower limit value VDmin. That is, when the rotation speed NM is lower than the rotation speed threshold value Nth, the first provisional value VMref1 becomes lower than the voltage lower limit value VDmin. Moreover, the voltage value (first voltage value V1) was set to a value equal to or greater than the lower limit voltage value VDmin.

[0069] The main machine 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 generates a second provisional value VMref2 of the main machine DC voltage command value VMref by limiting the first provisional value VMref1. In FIG. 5, the vertical axis of the main machine voltage command limiter 432 indicates the second provisional value VMref2, and the horizontal axis indicates the first provisional value VMref1. In the main machine voltage command limiter 432, the second provisional value VMref2 has a voltage value V1 (i.e., the first voltage value V1) until the first provisional value VVMref1 changes from 0 to the first voltage value V1, and when the first provisional value VMref1 becomes equal to or greater than the voltage value V1, the second provisional value VMref2 has the same value as the first provisional value VMref1. In other words, the main machine voltage command limiter 432 performs limiting so that the lower limit value of the second provisional value VMref2 becomes the first voltage value V1. As a result, even if the rotation speed NM is lower than the rotation speed threshold Nth and the first provisional value VMref1 is lower than the voltage lower limit value VDmin, the second provisional value VMref2 becomes the first voltage value V1 that is set to be equal to or higher than the voltage lower limit value VDmin.

[0070] The main machine 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 machine DC voltage command value VMref. Specifically, when the remaining capacity SoC is equal to or greater than the remaining capacity threshold Sth, the main machine voltage command selection unit 433 selects the first provisional value VMref1 as the main machine DC voltage command value VMref, and when the remaining capacity SoC is smaller than the remaining capacity threshold Sth, the main machine voltage command selection unit 433 selects the second provisional value VMref2 as the main machine DC voltage command value VMref.

[0071] As shown in FIG. 6, when the main motor voltage command generating unit 43 acquires the rotation speed NM of the traveling motor 10 (step S100), it generates a first provisional value VMref1 by referring to the main motor voltage command table 431 (step S110), and generates a second provisional value VMref2 by referring to the main motor voltage command limiter 432 (step S120).

[0072] Next, the remaining capacity SoC of the power 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 judgment result in step S140 is YES, that is, if the remaining capacity SoC is equal to or greater than the remaining capacity threshold value Sth, it is judged that the remaining capacity SoC of the power storage device 61 is sufficient, and a first provisional value VMref1 at which the main voltage VM may become smaller than the voltage lower limit value VDmin, that is, at which there is a possibility that the auxiliary power supply device 20 will not supply power to the auxiliary DC line 30, is set as the main DC voltage command value VMref (step S150), and the processing is terminated.

[0074] Furthermore, if the judgment result in step S140 is NO, i.e., if the remaining capacity SoC is smaller than the remaining capacity threshold value Sth, it is judged that the remaining capacity SoC of the power storage device 61 is insufficient, and the second provisional value VMref2 at which the main voltage VM is unlikely to become smaller than the voltage lower limit value VDmin, i.e., at which the auxiliary power supply device 20 supplies power to the auxiliary DC line 30, is set as the main DC voltage command value VMref (step S151), and the processing is terminated.

[0075] In the main machine voltage command generating unit 43 configured as above, if the rotation speed NM is lower than the rotation speed threshold Nth and the remaining capacity SoC is equal to or higher than the remaining capacity threshold Sth, the main machine DC voltage command value VMref is lower than the voltage lower limit value VDmin. On the other hand, if the remaining capacity SoC is lower than the remaining capacity threshold Sth, the main machine DC voltage command value VMref is equal to or higher than the first voltage value V1 even if the rotation speed NM is lower than the rotation speed threshold Nth. Here, since the first voltage value V1 is set to a value equal to or higher than the voltage lower limit value VDmin, the main machine DC voltage command value VMref is also equal to or higher than the voltage lower limit value VDmin.

[0076] FIG. 7 is a functional block diagram showing the outline of the processing contents of the power generation device control unit and the power consumption device control unit.

[0077] In FIG. 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 deviation (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 so as to reduce the deviation of the main engine voltage VM from 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<the main engine DC voltage command value VMref, the control signal VFref is increased to increase the output of the power generation device 11.

[0080] 7, power consuming device control unit 45 includes voltage control calculation unit 451 and calculation units 452 and 453.

[0081] The power consuming device control unit 45 first generates a command value VMrefR for the power consuming device by adding a predetermined voltage command offset ΔV (>0) to the main machine DC voltage command value VMref in the calculation unit 452. Next, the calculation unit 453 calculates the deviation (VM-VMrefR) between the main machine voltage VM and the command value VMrefR, and then generates a control signal CSR in the voltage control calculation unit 451 based on the calculation result. Here, the control signal CSR is assumed to be a PWM signal for controlling the on / off of a switching element of the power consuming device 17.

[0082] The voltage control calculation unit 451 uses a control law such as PI control to change the PWM duty of the control signal CSR so as to reduce the deviation of the main voltage VM from the command value VMrefR. Specifically, if the main voltage VM>command value VMrefR, the PWM duty is increased to increase the power consumption of the power consumption device 17.

[0083] In the present embodiment configured as described above, the power generation device control unit 44 and the power consumption device control unit 45 use the voltage command offset ΔV to set the command value VMrefR>main engine DC voltage command value VMref, so that when the traveling motor 10 is stopped or powered, the power generation device 11 controls the main engine voltage VM to the main engine DC voltage command value VMref and the power consumption of the power consumption device 17 becomes zero. Also, when the traveling motor 10 is in regeneration, the power consumption device 17 controls the main engine voltage VM to the command value VMrefR and the power generation device 11 sets the output to zero.

[0084] FIG. 8 is a functional block diagram illustrating the outline of the processing contents of the first DC / DC converter control unit.

[0085] In FIG. 8, the first DC / DC converter control unit 46 includes a current command generating unit 461 and a current control system 462.

[0086] The current command generating unit 461 generates a command value (current command value IBref) of the current IB based on the remaining capacity SoC, and outputs it to the current control system 462. Specifically, when the remaining capacity SoC is smaller than an upper limit value (remaining capacity upper limit value Smax), the current command value IBref is set to a predetermined negative command value I1 in order to charge the power storage device 61. When the remaining capacity SoC is equal to or larger than the remaining capacity upper limit value Smax, the current command value IBref is set to 0 (zero) in order to stop charging the power storage device 61. Note that when the current IB takes a negative value, it represents a charging current.

[0087] The current control system 462 generates a control signal CSD1 based on the current command value IBref, the current IB, and the main engine 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 deviation (IB-IBref) between the current IB and the current command value IBref in a calculation unit 465, and then generates a provisional signal CSD1temp of the control signal CSD1 in a current control calculation unit 463 based on the calculation result. The control signal CSD1 and the provisional signal CSD1temp are PWM signals for controlling the on / off of the switching elements of the first DC / DC converter 21. Specifically, the current control calculation unit 463 changes the PWM duty of the provisional signal CSD1temp so as to reduce the deviation of the current IB from the current command value IBref by using a control law such as PI control. For example, when the current IB>the current command value IBref, it means that the charging current is insufficient and it is necessary to reduce the current IB (to increase the charging current). In this case, the PWM duty 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, the increase in the output current from the first DC / DC converter 21 also increases the charging current to the power storage device 61 (i.e., the current IB decreases).

[0089] The on / off control unit 464 performs on / off control of the first DC / DC converter 21 based on the main machine voltage VM. Specifically, when the main machine voltage VM is equal to or higher than the voltage lower limit VDmin, the first DC / DC converter 21 can convert the voltage of the DC power on the main machine DC line 15 and output it to the auxiliary machine DC line 30, and outputs the provisional signal CSD1temp as it is as the control signal CSD1. Also, when the main machine voltage VM is lower than the voltage lower limit VDmin, the first DC / DC converter 21 does not convert the voltage of the DC power on the main machine DC line 15 (power cannot be supplied to the auxiliary machine DC line 30). In this case, the control signal CSD1 is generated and output so that all switching elements of the first DC / DC converter 21 are turned off regardless of the PWM duty of the provisional signal CSD1temp.

[0090] The effects of the present embodiment configured as above will be described.

[0091] In the present embodiment, when the main voltage VM is higher than a predetermined voltage lower limit VDmin, the first DC / DC converter 21 is capable of outputting power to the auxiliary DC line 30. By limiting the range of the main voltage VM that the first DC / DC converter 21 can output in this manner, the first DC / DC converter 21 can be made smaller in size.

[0092] When the rotation speed NM of the traveling motor 10 is lower than a predetermined rotation speed threshold Nth and the remaining capacity SoC of the power storage device 61 is equal to or higher than a predetermined remaining capacity threshold Sth, the control device 40 controls the power generation device 11 so that the main voltage VM is lower than the voltage lower limit VDmin. That is, by focusing on the fact that the voltage to be applied to the traveling motor 10 may be relatively low when the rotation speed is low, the loss 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 element on the main DC line 15 side can be reduced, and a sufficient margin can be secured for the withstand voltage. At this time, although the first DC / DC converter 21 cannot supply DC power to the auxiliary DC line 30, the remaining capacity SoC of the power storage device 61 has a margin, so that the auxiliary device 31 can be stably driven by discharging from the power storage device 60.

[0093] When the remaining capacity SoC of the power storage device 61 is smaller than a predetermined remaining capacity threshold Sth, the control device 40 controls the power generation device 11 so that the main voltage VM becomes equal to or greater than a first voltage value V1, and controls the auxiliary power supply device 20 so as to charge the power storage device 61. In addition, the first voltage value V1 is set to a value equal to or greater than a lower limit voltage value VDmin. At this time, the first DC / DC converter 21 can supply power to the auxiliary DC line 30, so that the auxiliary device 31 can be stably driven by the output of the first DC / DC converter 21 while the power storage device 61 is charged.

[0094] In this way, when the remaining capacity SoC of the power storage device 61 becomes small, the first DC / DC converter 21 can be operated to charge the power storage device 61, so that the capacity of the power storage device 61 can be reduced to the minimum required, and the power storage device 61 can be made smaller.

[0095] That is, in this embodiment, the DC / DC converter can be made smaller, a stable power supply to the auxiliary devices can be ensured, and loss and noise that occur when the vehicle is stopped or traveling at low speeds can be reduced.

[0096] <Second embodiment> A second embodiment of the present invention will be described with reference to FIGS.

[0097] In this embodiment, in addition to the configuration of the first embodiment, a second DC / DC converter 67 is disposed between the power storage device 61 and the switch 63. In this embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0098] FIG. 9 is a diagram that shows a schematic configuration of an auxiliary power supply device according to this embodiment.

[0099] In FIG. 9, an auxiliary power supply device 20A includes a first DC / DC converter 21 and a power storage device 60A.

[0100] An input section of the first DC / DC converter 21 is connected to the main DC line 15, and an output section is connected to the auxiliary DC line 30. In addition, the power storage device 60A is connected to the auxiliary DC line 30.

[0101] The power storage device 60A includes a power 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 power storage apparatus 60A, the second DC / DC converter 67 is connected between the power storage device 61 and the switch 63. The control signal CSA includes a control signal CSD2 for the second DC / DC converter 67. The second DC / DC converter 67 is a DC / DC converter capable of bidirectional operation, and is capable of charging and discharging the power storage device 61.

[0103] FIG. 10 is a diagram illustrating a schematic configuration of the second DC / DC converter.

[0104] 10, the second DC / DC converter 67 is made up of upper and lower arms (half bridge circuit) 671 formed 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 a control signal CSD2 from the control device 40. Each element is controlled based on, for example, PWM, and the control signal CSD2 is a PWM duty or a PWM signal. Note that, as the second DC / DC converter, other circuit configurations may be used as long as they are DC / DC converters capable of bidirectional operation.

[0106] Capacitors 673, 674 are connected to the input side and the output side of the second DC / DC converter 67, respectively. At this time, the input voltage of the second DC / DC converter 67 is equal to the voltage VB of the power storage device 61. Furthermore, when the 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 power 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 power storage device 61 and the 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 of the choke coil 672 increases or decreases. During the on-period of the switching element Q6, the chopper voltage VCH becomes almost 0 (zero), and the current IL increases in the direction of discharge from the power storage device 61 (the direction of the arrow). During the on-period of the 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 the capacitor 673 is sufficiently large, the charge / discharge current IB becomes the DC component (average value) of the current IL in the steady state. By controlling the current IL and thus the polarity and absolute value of the current IB by PWM, the charge / discharge current of the power storage device 61 can be controlled.

[0108] It is also possible to connect the power 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 power storage device 61 so that the voltage VB is higher than the auxiliary voltage VA.

[0109] FIG. 11 is a functional block diagram showing an outline of the processing contents of the control device according to the present embodiment.

[0110] In FIG. 11, the control device 40A is composed of a drive control unit 41, an SoC calculation unit 42, a main engine 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 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 the control signal CSD1 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, the auxiliary voltage VA, the current IB, and the control signals CSS1 and CSS2 from the storage device switch control unit 47, and outputs the control signal CSD2 to the drive control unit 675.

[0113] FIG. 12 is a functional block diagram showing an outline of the processing contents of the first DC / DC converter control unit according to this embodiment.

[0114] In FIG. 12, a first DC / DC converter control unit 46 A 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 so as to control the auxiliary voltage VA in accordance with a first command value for the auxiliary voltage VA (first voltage command value VAref1) generated internally.

[0116] The first DC / DC converter control unit 46A first calculates the deviation (VAref1-VA) between the first voltage command value VAref1 (predetermined voltage V2) and the auxiliary voltage VA in a calculation unit 467, and generates a provisional signal CSD1temp of the control signal CSD1 in a voltage control calculation unit 466 based on the calculation result. Specifically, the voltage control calculation unit 466 generates (changes) the provisional signal CSD1temp so as to reduce the deviation of the auxiliary voltage VA from the first voltage command value VAref1 by using a control law such as PI control. The voltage V2 set as the first voltage command value VAref1 is set to be within the operating voltage range of the auxiliary device 31.

[0117] The on / off control unit 464 performs on / off control of the first DC / DC converter 21 based on the main machine voltage VM. Specifically, when the main machine voltage VM is equal to or higher than the voltage lower limit VDmin, the first DC / DC converter 21 can convert the voltage of the DC power on the main machine DC line 15 and output it to the auxiliary machine DC line 30, and outputs the provisional signal CSD1temp as it is as the control signal CSD1. Also, when the main machine voltage VM is lower than the voltage lower limit VDmin, the first DC / DC converter 21 does not convert the voltage of the DC power on the main machine DC line 15 (power cannot be supplied to the auxiliary machine DC line 30). In this case, the control signal CSD1 is generated and output so that all switching elements of the first DC / DC converter 21 are turned off regardless of the PWM duty of the provisional signal CSD1temp.

[0118] FIG. 13 is a functional block diagram illustrating the second DC / DC converter control section.

[0119] In FIG. 13, the second DC / DC converter control unit 48 includes a current limit value generating unit 481 and a voltage control system 482.

[0120] Moreover, 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 (current limit value IBlim) of the current IB based on the remaining capacity SoC of the power storage device 61. Specifically, when the remaining capacity SoC is smaller than the upper limit value (remaining capacity upper limit value Smax), the current limit value generation unit 481 sets the current limit value IBlim to a predetermined negative value I1. When the remaining capacity SoC is equal to or larger than the remaining capacity upper limit value Smax, the current limit value generation unit 481 sets 0 (zero) to the current limit value IBlim.

[0122] The voltage control system 482 generates a control signal CSD2 for the second DC / DC converter 67 so as to control the auxiliary voltage VA in accordance with a second command value for the auxiliary voltage VA (second voltage command value VAref2) generated internally, and outputs the control signal CSD2 to the drive control device 675.

[0123] In the voltage control system 482, first, a calculation unit 488 calculates the deviation (VAref2-VA) between the auxiliary voltage VA and the second voltage command value VAref2, and a voltage control calculation unit 483 generates a first command value (first current command value IBref1) for the current IB based on the calculation result. Specifically, the voltage control calculation unit 483 changes the first current command value IBref1 using a control law such as PI control so as to reduce the deviation of the auxiliary voltage VA from the second voltage command value VAref2. For example, when the auxiliary voltage VA<the second voltage command value VAref2, the first current command value IBref1 is increased to increase the discharge current of the power storage device 61. The voltage V3 set as the second voltage command value VAref2 is set to be lower than the above-mentioned voltage V2 and to be within the operating voltage range of the auxiliary device 31.

[0124] The variable limiter 484 performs limiting processing on the first current command value IBref1 so that the lower limit value becomes IBlim, and generates the result as a second command value (second current command value IBref2) for the current IB.

[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 deviation (IBref2-IB) between the second current command value IBref2 and the current IB using a calculation unit 489, and generates a provisional signal CSD2temp of the control signal CSD2 using a current control calculation unit 486 based on the calculation result. Specifically, the current control calculation unit 486 changes the PWM duty of the provisional signal CSD2temp so as to reduce the deviation of the current IB from the second current command value IBref2 using a control law such as PI control. The control signal CSD2 and the provisional signal CSD2temp are PWM signals for controlling the on / off of the switching elements of the second DC / DC converter 67.

[0127] The on / off control unit 487 performs on / off control of the second DC / DC converter 67 based on the control signals CSS1, CSS2 of the switches 62, 63 of the power storage device 60. Specifically, when the switches 62, 63 are both closed, that is, when the power storage device 61 is ready to be charged or discharged, the interim signal CSD2temp is output as is as the control signal CSD2. In addition, when at least one of the switches 62, 63 is open, the power 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 of the interim signal CSD2temp.

[0128] The operation of the present embodiment configured as above will be described.

[0129] When the rotation speed NM is lower than the speed threshold Nth and the remaining capacity SoC is equal to or higher than the remaining capacity threshold Sth, the control device 40 controls the power generation device 11 so that the main voltage VM becomes lower than the voltage lower limit VDmin. At this time, the first DC / DC converter 21 cannot supply power to the auxiliary DC line 30, so the second DC / DC converter 67 discharges the power storage device 61 to drive the auxiliary device 31. The second DC / DC converter 67 controls the auxiliary voltage VA to be equal to the voltage V3, and the current IB is determined by the power consumption of the auxiliary device 31.

[0130] Moreover, when the remaining capacity SoC is smaller than Sth, the control device 40 controls the power generation device 11 so that the main voltage VM becomes equal to or higher than the first voltage value V1 (≧VDmin). At this time, the first DC / DC converter 21 operates so that the auxiliary voltage VA becomes the voltage V2. Here, since the voltage V2>V3, the first DC / DC converter 21 can output with priority over the discharging operation of the second DC / DC converter 67, and as a result, the auxiliary voltage VA is controlled to become the voltage V2. The second DC / DC converter 67 operates to reduce the auxiliary voltage VA to the voltage V3, and reduces the current IB, that is, increases the charging current. However, the current IB is limited to the current I1 by the variable limiter 484. The power consumption of the auxiliary device 31 and the charging power of the power storage device 61 are all supplied from the first DC / DC converter 21. However, when the remaining capacity SoC reaches the upper limit value Smax, the charging current is limited to 0 (zero).

[0131] The other configurations are similar to those of the first embodiment.

[0132] The present embodiment configured as above can also provide the same effects as the first embodiment.

[0133] Furthermore, in this embodiment, since the second DC / DC converter 67 is connected between the auxiliary equipment 31 and the power storage device 61, it is no longer necessary to determine the voltage specifications of the power storage device 61 so that the voltage VB falls within the operating voltage range of the auxiliary equipment 31, and this increases the degree of freedom in determining the voltage specifications of the power storage device 61.

[0134] Furthermore, even if the voltage VB changes depending on 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 storage device 61 changes over a wide range, the auxiliary device 31 can be driven stably.

[0135] <Third embodiment> A third embodiment of the present invention will be described with reference to FIGS.

[0136] In this embodiment, a second DC / DC converter 67 is disposed between the first DC / DC converter 21 and the power storage device 61 (more specifically, a switch 62), and the auxiliary device 31. In this embodiment, the same members as those in the first and second embodiments are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0137] FIG. 14 is a diagram that shows a schematic configuration of an auxiliary power supply device according to the present embodiment.

[0138] 14, auxiliary power supply 20B includes a first DC / DC converter 21 and a power storage device 60B. Power storage device 60B is composed of a power 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 20B, the second DC / DC converter 67 of the power 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 part of the first DC / DC converter 21 is connected to the main DC line 15, and the output part is connected to the input part of the second DC / DC converter 67 of the power storage device 60B. In addition, the power storage device 61 is connected to the input part of the second DC / DC converter 67 via the switches 62 and 63. At this time, the output voltage of the second DC / DC converter 67 becomes the auxiliary voltage VA. In addition, after the switches 62 and 63 are closed, the input voltage of the second DC / DC converter 67 becomes the voltage VB. Note that the control signal CSA includes a control signal CSD2 of the second DC / DC converter 67.

[0140] The second DC / DC converter 67 in this embodiment does not have to be configured to be capable of bidirectional operation. Therefore, the circuit configuration of the first DC / DC converter 21 (see FIG. 3) shown in the first embodiment or the second DC / DC converter 67 (see FIG. 10) shown in the second embodiment may be used as the circuit configuration of the second DC / DC converter 67. However, when using the circuit configuration shown in the second DC / DC converter 67 (see FIG. 10) shown in the second embodiment, if the voltage VB of the power storage device 61 is set higher than the operating voltage of the auxiliary device 31, the side to which the capacitor 673 is connected needs to be the output side (the auxiliary device 31 side).

[0141] FIG. 15 is a functional block diagram showing an outline of the processing contents of the control device according to the present embodiment.

[0142] In FIG. 15, the control device 40B is composed of a drive control unit 41, an SoC calculation unit 42, a main engine 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 storage device switch control unit 47, and a second DC / DC converter control unit 68B.

[0143] FIG. 16 is a functional block diagram illustrating a second DC / DC converter control section according to the present embodiment.

[0144] 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 second command value VAref2 for the auxiliary voltage VA in a calculation unit 491, and generates a control signal CSD2 for the second DC / DC converter 67 in a voltage control calculation unit 490 based on the calculation result. Specifically, the voltage control calculation unit 490 changes the control signal CSD2 so as to reduce the deviation of the auxiliary voltage VA from the second voltage command value VAref2 by using a control law such as PI control. Note that, in this embodiment, the value of the second voltage command value VAref2 is set to the voltage V3 as in FIG. 13 of the second embodiment, but may be set to the voltage V2 as in FIG. 12.

[0146] The operation of the present embodiment configured as above will be described.

[0147] When the rotation speed NM of the travel motor 10 is lower than the speed threshold Nth and the remaining capacity SoC is equal to or higher than the remaining capacity threshold Sth, the control device 40B controls the power generation device 11 so that the main voltage VM becomes lower than the voltage lower limit VDmin. At this time, the first DC / DC converter 21 cannot supply power to the auxiliary DC line 30 side (i.e., the input part of the second DC / DC converter 67), so the second DC / DC converter 67 discharges the power storage device 61 to drive the auxiliary device 31. The second DC / DC converter 67 controls the auxiliary voltage VA to be voltage V3, and the current IB is determined by the power consumption of the auxiliary device 31.

[0148] Furthermore, when the remaining capacity SoC is smaller than the remaining capacity threshold Sth, the control device 40B controls the power generation device 11 so that the main voltage VM becomes equal to or higher than the first voltage value V1 (≧VDmin). At this time, the first DC / DC converter 21 operates to set the current IB to a current value I1, and charges the power storage device 61. The power consumption of the auxiliary device 31 and the charging power of the power storage device 61 are all supplied from the first DC / DC converter 21. However, when the remaining capacity SoC of the power storage device 61 reaches an upper limit value Smax, the charging current is limited to 0 (zero).

[0149] The other configurations are similar to those of the first and second embodiments.

[0150] The present embodiment configured as above can also provide the same effects as the first and second embodiments.

[0151] In the present embodiment, the first DC / DC converter 21 and the 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 insulating DC / DC converter with a transformer is used as the first DC / DC converter 21, and a non-insulating DC / DC converter without a transformer is used as the second DC / DC converter 67. However, in the present embodiment, a non-insulating DC / DC converter can be applied to the first DC / DC converter 21, and an insulating DC / DC converter can be applied to the second DC / DC converter 67, so that insulation can be achieved between the main DC line 15 and the auxiliary DC line 30. In particular, in the present embodiment, it is assumed that the main voltage VM is changed over a wide range, and therefore these configurations can reduce the fluctuations in the input voltage and output voltage of the insulating DC / DC converter, and as a result, the insulating DC / DC converter can be made smaller.

[0152] <Additional Notes> The present invention is not limited to the above-described embodiments, and includes various modifications and combinations within the scope of the gist of the present invention. The present invention is not limited to those having all the configurations described in the above-described embodiments, and includes those in which some of the configurations are deleted. The above-described configurations, functions, etc. may be realized by designing some or all of them as an integrated circuit, for example. The above-described configurations, functions, etc. may be realized by software, in which a processor interprets and executes a program that realizes each function. [Explanation of symbols]

[0153] 1...vehicle frame, 2L, 2R...driven wheels (front wheels), 3L, 3R...driving wheels (rear wheels), 4...operator cab, 5...cargo platform (vessel), 5a...pin joint, 6...hoist cylinder, 7...grid box, 8...control cabinet, 9...fuel tank, 10L, 10R...travel motor, 11...power generating device, 12...engine, 13...main engine generator, 14...rectifier circuit, 15...main engine DC line, 16...inverter, 17...power consumption device, 18...voltage detector, 19...capacitor, 20, 20A, 20B...auxiliary power supply device, 21...first DC / DC converter, 30...auxiliary DC line, 31...auxiliary device, 32...voltage detector, 33...con condenser, 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...electrically driven dump truck

Claims

1. A power generation device, A main DC line to which the DC power generated by the power generation device is supplied, A traveling motor, An inverter that drives the traveling motor with the DC power supplied to the main DC line, An auxiliary machine device, An auxiliary machine DC line that supplies DC power for driving the auxiliary machine device, A DC / DC converter capable of converting the DC voltage of the main DC line and supplying it to the auxiliary machine DC line when the DC voltage of the main DC line is equal to or higher than a predetermined voltage threshold, and a power storage device that stores the power that can be supplied to the auxiliary machine DC line. An auxiliary machine power supply device having, A control device that controls the power generation device and the auxiliary machine power supply device, The control device controls the power generation device and the auxiliary machine power supply device according to the rotational speed of the traveling motor and the remaining charge amount of the power storage device. An electric working vehicle characterized by that.

2. In the electric working vehicle according to Claim 1, The control device, When the rotational speed of the traveling motor is lower than a predetermined speed threshold and the remaining charge amount of the power storage device is equal to or higher than a predetermined remaining amount threshold, the power generation device is controlled so that the voltage of the main DC line becomes lower than the voltage threshold, When the rotational speed of the traveling motor is lower than the predetermined speed threshold and the remaining charge amount of the power storage device is smaller than the remaining amount threshold, while controlling the power generation device so that the voltage of the main DC line becomes higher than the voltage threshold, the auxiliary machine power supply device is controlled to charge the power storage device. An electric working vehicle characterized by that.

3. In the electric working vehicle according to Claim 1, The control device, A main machine voltage command table that defines the relationship between the rotational speed of the traveling motor and a first provisional voltage command value generated as a provisional value of a command value for controlling the power generation device, It has a main machine voltage command limit table that defines the relationship between the first provisional voltage command value generated according to the main machine voltage command table and the second provisional voltage command value obtained by setting a voltage lower limit value to the first provisional voltage command value. When the remaining charge amount of the power storage device is equal to or greater than a predetermined remaining amount threshold value, the power generation device is controlled according to the first provisional voltage command value, and when the remaining charge amount of the power storage device is smaller than the remaining amount threshold value, the power generation device is controlled according to the second provisional voltage command value. The electric working vehicle is characterized by this.

4. In the electric working vehicle according to claim 3, In the main machine voltage command table, when the rotational speed of the traveling motor is lower than a predetermined speed threshold value, the first provisional voltage command value becomes lower than the voltage lower limit value, and when the rotational speed is higher than the speed threshold value, the first provisional voltage command value becomes higher than the voltage lower limit value. It is defined as follows: The main machine voltage command limit table is characterized in that the voltage lower limit value is defined to be a value larger than the voltage threshold value. The electric working vehicle is characterized by this.

5. In the electric working vehicle according to claim 2, The control device is When the DC voltage of the main machine DC line is equal to or higher than a predetermined voltage threshold value and the remaining charge amount of the power storage device is smaller than a predetermined remaining capacity upper limit value, A current target value, which is the target value of the current supplied from the auxiliary machine DC line to the power storage device to charge the power storage device, is set. The electric working vehicle is characterized in that the DC / DC converter is controlled so that the deviation between the current value supplied to the power storage device and the current target value becomes small.

6. In the electric working vehicle according to claim 2, When the DC voltage of the main machine DC line is smaller than a predetermined voltage threshold value, the conversion of the DC voltage of the main machine DC line by the DC / DC converter and the supply to the auxiliary machine DC line are stopped. The electric working vehicle is characterized by this.

7. In the power-operated work vehicle according to claim 2, the auxiliary power supply device, in addition to a first DC / DC converter that is a DC / DC converter capable of converting the DC voltage of the main machine DC line and supplying it to the auxiliary machine DC line when the DC voltage of the main machine DC line is equal to or higher than a predetermined voltage threshold, further includes a second DC / DC converter capable of converting DC voltage between the power storage device and the auxiliary machine DC line and supplying it to each other, the control device, a first DC / DC converter control unit that generates a control signal for the first DC / DC converter based on the voltage of the main machine DC line and the voltage of the auxiliary machine DC line, and a second DC / DC converter control unit that generates a control signal for the second DC / DC converter based on the remaining charge amount and discharge current of the power storage device, when the voltage of the main machine DC line is equal to or higher than the voltage threshold, the first DC / DC converter control unit generates a control signal for the first DC / DC converter so that the deviation between the voltage of the auxiliary machine DC line and a predetermined first voltage command value becomes small, the second DC / DC converter control unit, when the remaining charge amount of the power storage device is smaller than a predetermined remaining charge amount upper limit value, includes a current limit value generation unit that sets the current value in the charging direction of the power storage device as a current limit value, when the voltage of the auxiliary machine DC line is lower than a predetermined second voltage command value, a voltage control arithmetic unit that increases a predetermined first current command value, a variable limiter that performs a limiter process on the first current command value so that the first current command value becomes equal to or higher than the current limit value to generate a second current command value, and a voltage control system having a current control system that controls charging and discharging of the power storage device, the current control system generates a control signal for the second DC / DC converter so that the deviation between the current value in the charging direction of the power storage device and the second current command value becomes small, wherein the second voltage command value is set lower than the first voltage command value. The power-operated work vehicle is characterized by this.

8. In the electric work vehicle according to claim 2, the auxiliary power supply device, in addition to a first DC / DC converter which is a DC / DC converter capable of converting the DC voltage of the main machine DC line and supplying it to the auxiliary machine DC line when the DC voltage of the main machine DC line is equal to or higher than a predetermined voltage threshold value, further has a second DC / DC converter provided on the auxiliary machine DC line and capable of converting the DC voltages of the first DC / DC converter and the power storage device and supplying them to the auxiliary machine device, the control device, a first DC / DC converter control unit that generates a control signal for the first DC / DC converter based on the remaining power amount of the power storage device, the voltage of the main machine DC line, and the current value in the discharge direction of the power storage device, and 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 machine DC line, the first DC / DC converter control unit, has a current command generation unit that sets the current value in the charging direction of the power storage device as the current command value when the remaining power amount of the power storage device is smaller than a predetermined upper limit value of the remaining power amount, and a current control system that generates a control signal for the first DC / DC converter so that the deviation between the current value in the charging direction of the power storage device and the current command value becomes small when the voltage of the main machine DC line is equal to or higher than the voltage threshold value, wherein the second DC / DC converter control unit generates a control signal for the first DC / DC converter so that the deviation between the voltage of the auxiliary machine DC line and a predetermined voltage command value becomes small. An electric work vehicle characterized by this.

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