Electric drive system for electric work machine

Abstract

To prevent transmission of abnormal voltage to a power converter in the event of abnormal voltage from an external power source, and to perform electrically safe maintenance work by cutting off the power from the external power source as well as an internal battery with a simple operation when performing maintenance on electric circuit equipment.SOLUTION: A cutoff switch 45 is provided to cut off the supply of control voltage from a control battery 41. Further, an AC box 100 that includes power lines L11, L21, and L31 and a neutral line N1 is provided with: an external power relay 100d; and a cutoff control device 120 which is connected to the power lines L11, L21, and L31, and a control voltage supply path 46, and switches the external power supply relay 100d from a connection position to a cutoff position and cuts off the power lines L11, L21, and L31 when a voltage abnormality occurs in an external power supply 92 or when the control voltage is cut off by the cutoff switch 45.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electric drive system for an electric working machine such as a hydraulic excavator that performs various operations by an electric motor.

Background Art

[0002] An electric working machine such as a hydraulic excavator that drives a hydraulic pump or the like by an electric motor and performs various operations by a plurality of actuators is used in an environment where exhaust gas emission is not preferable, such as an indoor or underground working environment, due to features such as not emitting exhaust gas from an engine and being low-noise.

[0003] Such an electric working machine is known to drive an electric motor using an internal battery and an external power source as a power source to perform operations, and an example thereof is described in, for example, Patent Document 1.

[0004] Patent Document 1 discloses an electric working machine including an internal battery, a booster circuit that boosts a DC voltage supplied from the internal battery, an inverter that converts the boosted DC voltage into an AC voltage, an electric motor driven by the AC voltage supplied from the inverter, a hydraulic pump driven by the electric motor, and a plurality of actuators driven using the hydraulic pressure generated by the hydraulic pump. In this electric working machine, an AC / DC converter that converts an AC voltage into a DC voltage is connected to the input side of the inverter, a commercial power supply connector to which a commercial AC power supply as an external power source can be connected is connected to the input side of the AC / DC converter, a charging circuit for charging the internal battery is provided between the output side of the AC / DC converter and the internal battery, and the internal battery can be charged and the electric motor can be driven using the commercial AC power supply.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] However, the electric work machine described in Patent Document 1 has the following problems.

[0007] For example, if another load device is connected to the commercial AC power supply (external power supply) and this other load device operates, or if the neutral line of the commercial AC power supply is grounded through excessive impedance, an excessive voltage may be generated in the commercial AC power supply, potentially damaging the AC-DC converter.

[0008] Furthermore, when performing maintenance on the electrical circuit equipment of electric power machinery, it is necessary to interrupt the power supplied from the power source to the electrical circuit equipment in order to ensure that workers can perform the work safely. To interrupt the power supplied from the power source to the electrical circuit equipment, a power interruption device must be installed at the power source, and if there is an external power source in addition to the internal battery as a power source, a power interruption device must also be installed at the external power source.

[0009] However, if a power cutoff device is also installed for the external power supply, maintenance work requires operating the power cutoff devices for both the internal battery and the external power supply, which presents a cumbersome procedure.

[0010] The object of the present invention is to provide an electric drive system for an electric work machine that uses an internal battery and an external power supply to drive an electric motor and perform work, which prevents abnormal voltage from being transmitted to the power converter when the voltage of the external power supply is abnormal, and which allows for electrical safe maintenance work by easily shutting off power from both the internal battery and the external power supply when performing maintenance on electrical circuit equipment. [Means for solving the problem]

[0011] To achieve the above objective, the present invention provides an electric drive system for an electric work machine comprising: an electric motor that generates power for driving; an inverter that drives the electric motor; an internal battery that supplies power to the inverter for driving the electric motor; an external power connection device; a power converter connected to the external power connection device and rectifying power supplied from an external power source to generate power for charging the internal battery; and a control power supply that supplies a control voltage to the inverter and the power converter via a control voltage supply path, wherein the system further comprises a cutoff switch for cutting off the supply of the control voltage from the control power supply, the external power connection device comprising: a power line connecting the external power supply and the power converter; an external power relay connected to the power line and switching from a connection position to a cutoff position to cut off the power line; and a cutoff control device connected to the power line and the control voltage supply path, which switches the external power relay from the connection position to the cutoff position and cuts off the power line when a voltage abnormality occurs in the external power supply or when the control voltage is cut off by the cutoff switch.

[0012] By providing a circuit breaker control device on the external power supply connection device in this manner, if an abnormal voltage occurs in the external power supply, or if the control voltage is interrupted by the circuit breaker switch, the external power relay is switched from the connection position to the circuit breaker position, thereby cutting off the power line. This prevents the abnormal voltage from being transmitted to the power converter when the external power supply voltage is abnormal, and thus prevents damage to the power converter.

[0013] Furthermore, when the control voltage is interrupted by the cutoff switch, electrical circuit equipment maintenance can be performed with a simple operation of the cutoff switch, which cuts off power not only from the internal battery but also from the external power supply, allowing for electrically safe maintenance work. can. [Effects of the Invention]

[0014] According to the present invention, when the voltage of an external power supply is abnormal, it is possible to prevent the abnormal voltage from being transmitted to a power conversion device and to prevent the power conversion device from being damaged. Further, when performing maintenance on an electric circuit device, by a simple operation of operating a cutoff switch, not only the internal battery but also the power from the external power supply can be cut off, and an electrically safe maintenance work can be performed.

Brief Description of the Drawings

[0015] [Figure 1] FIG. 1 is a diagram showing the overall configuration of an electric drive system of an electric working machine according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the circuit configuration of a relay for a vehicle body controller. [Figure 3] FIG. 3 is a diagram showing the appearance of an electric hydraulic working machine on which the electric drive system of the present embodiment is mounted. [Figure 4] FIG. 4 is a diagram showing the overall configuration of an electric drive system of an electric working machine according to a second embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

[0017] <First Embodiment> A first embodiment of the present invention will be described.

[0018] ~Electric Drive System~ FIG. 1 is a diagram showing the overall configuration of an electric drive system of an electric working machine according to a first embodiment of the present invention.

[0019] In FIG. 1, the electric drive system of the electric working machine includes an electric motor 1 that generates driving power, a hydraulic drive system 10A that operates based on the power generated by the electric motor 1, and a power supply system 10B that supplies power to the electric motor 1.

[0020] The hydraulic drive system 10A has a hydraulic pump 2 driven by an electric motor 1, and a plurality of actuators driven by the pressure oil discharged from the hydraulic pump 2, namely a boom cylinder 3a, an arm cylinder 3b, a bucket cylinder 3c, a swing motor 3d (see FIG. 3), travel motors 3f, 3g (see FIG. 3), and a swing cylinder and a blade cylinder not shown, and a control valve 4 for controlling the flow rate and direction of the pressure oil supplied from the hydraulic pump 2 to the plurality of actuators 3a, 3b, 3c, 3d, 3f, 3g...

[0021] The power supply system 10B includes an inverter 60 that drives the electric motor 1, a drive battery 70 which is an internal battery that supplies power to drive the electric motor 1 to the inverter 60, an external power supply connection device 100 called an AC box (hereinafter referred to as the AC box) to which a three-phase AC power supply 92 (hereinafter referred to as the external power supply), which is an external power source, is connected, a power conversion device 90 that rectifies the external power supplied from the external power supply 92 to charge the drive battery 70 and generates power to supply to the inverter 60 and the DC / DC converter 40, a DC / DC converter 40 that steps down the voltage of the power output from the drive battery 70 and the power conversion device 90 to generate control power, a junction box 65 that distributes and supplies the power output from the drive battery 70 and the power conversion device 90 to the inverter 60 and the DC / DC converter 40, a vehicle body controller 50 that controls the drive battery 70, the power conversion device 90, and the inverter 60, and a control power supply system 30 that includes a control battery 41 (control power source) connected to the DC / DC converter 40 and that supplies a control voltage to related electric circuit devices (vehicle body controller 50, inverter 60, drive battery 70, power conversion device 90, AC box 100) together with the DC / DC converter 40.

[0022] The drive battery 70 includes a plurality of battery modules 70b, a battery relay 70c that switches the positive side of the plurality of battery modules 70b between connected and disconnected positions, a battery relay 70d that switches the negative side of the plurality of battery modules 70b between connected and disconnected positions, a pre-charge relay 70e and a pre-charge resistor 70f that prevent excessive current from flowing when the battery relays 70c and 70d are switched to the connected position, and a battery management unit (hereinafter referred to as BMU) 70a that monitors the status of the plurality of battery modules 70b, transmits the status information to the vehicle controller 50, receives commands from the vehicle controller 50 and controls the battery relays 70c, 70d and the pre-charge relay 70e.

[0023] The AC box 100 includes a first power supply connector 101 to which the three-phase AC lines L10, L20, L30 of the external power supply 92 and the neutral line N0 are connected, a second power supply connector 102 to which the power converter 90 is connected via the three-phase AC lines L12, L22, L32 and the neutral line N2, three-phase AC lines L11, L21, L31 (hereinafter referred to as power lines) and the neutral line N1 connected to the first power supply connector 101 and the second power supply connector 102 and connecting the external power supply 92 and the power converter 90, an external power relay 100d connected to the power lines L11, L21, L31 and the neutral line N1, which switches from the connection position to the disconnection position to disconnect the power lines L11, L21, L31, The system includes a power interruption control device 120 that is connected to L31 and the neutral line N1 and the control voltage supply path 46, and switches the external power relay 100d to the interruption position, thereby interrupting power lines L11, L21, L31 and the neutral line N1, when a voltage abnormality occurs in the external power supply 92 or when the control voltage is interrupted by the interruption switch 45 (described later).

[0024] The external power relay 100d is configured to switch from the disconnected position to the connected position when power is supplied from the external power supply 92, and the disconnection control device 120 disconnects the power supply from the external power supply 92 to the external power relay 100d when a voltage abnormality occurs in the external power supply 92 or when the control voltage is interrupted by the disconnection switch 45.

[0025] More specifically, the tripping control device 120 includes a voltage monitoring device 100a connected to power lines L11, L21, L31 and neutral line N1, which monitors voltage abnormalities in the external power supply 92; a voltage monitoring relay 100b which is in the connected position when the voltage monitoring device 100a does not detect voltage abnormalities in each phase of power lines L11, L21, L31 and neutral line N1, and switches from the connected position to the tripped position when the voltage monitoring device 100a detects a voltage abnormality, and switches the external power relay 100d from the connected position to the tripped position; and a control power supply determination relay 100c which is connected to the control battery 41 via a vehicle controller relay 42 and a control voltage supply path 46, which is in the connected position when the control voltage from the control battery 41 is not tripped by the tripped switch 45, and switches from the connected position to the tripped position when the tripped switch 45 detects the tripping of the control voltage, and switches the external power relay 100d from the connected position to the tripped position.

[0026] The external power relay 100d has a switch section 100d1 and a control coil section 100d2, the voltage monitoring relay 100b has a switch section 100b1 and a control coil section 100b2, and the control power judgment relay 100c has a switch section 100c1 and a control coil section 100c2.

[0027] The switch unit 100d1 of the external power relay 100d is connected to power lines L11, L21, and L31, and when the switch unit 100d1 switches from the connected position to the disconnected position, it disconnects power lines L11, L21, and L31.

[0028] The control coil section 100d2 of the external power relay 100d is connected to one of the power lines L11, L21, L31, in the illustrated embodiment, to the AC line L11, via the switch section 100b1 of the voltage monitoring relay 100b and the switch section 100c1 of the control power judgment relay 100c. The switch section 100b1 of the voltage monitoring relay 100b and the switch section 100c1 of the control power judgment relay 100c are connected in series between the AC line L11 and the control coil section 100d2 of the external power relay 100d. As a result, when at least one of the switch section 100b1 of the voltage monitoring relay 100b and the switch section 100c1 of the control power judgment relay 100c is switched to the tripped position, the switch section 100d1 of the external power relay 100d is switched to the tripped position.

[0029] The control coil section 100b2 of the voltage monitoring relay 100b is connected to the signal circuit 100a1 of the voltage monitoring device 100a. When the voltage monitoring device 100a detects a voltage anomaly, it outputs a control voltage to the signal circuit 100a1 and switches the switch section 100b1 of the voltage monitoring relay 100b from the connected position to the disconnected position. The voltage monitoring device 100a operates using the power of the three-phase AC power supply 92 being monitored and generates the control voltage.

[0030] The control coil section 100c2 of the control power supply determination relay 100c is connected to the signal circuit 100c3 which is connected to the control voltage supply path 46. When no control voltage is supplied to the signal circuit 100c3, the switch section 100c1 of the control power supply determination relay 100c is switched from the connected position to the disconnected position.

[0031] The control power supply system 30 includes, in addition to the DC / DC converter 40 and control battery 41 described above, a relay 42 for the vehicle controller, a key switch 43, a charging start switch 44, a cutoff switch 45, and a control voltage supply path 46. The DC / DC converter 40 and control battery 41 are connected to the relay 42 for the vehicle controller via a power line 41a, and the relay 42 for the vehicle controller is connected via a control voltage supply path 46 to the vehicle controller 50, the BMU 70a of the drive battery 70, the power converter 90, the inverter 60, and the signal circuit 100c3 of the control power supply determination relay 100c.

[0032] The cutoff switch 45 cuts off the supply of control voltage from the control battery 41 and is located on the circuit 41G that grounds the negative terminal of the control battery 41.

[0033] The disconnect switch 45 is normally in the connected position, in which case the power output from the DC / DC converter 40 and the control battery 41 is directed to the vehicle controller relay 42. The vehicle controller relay 42 switches whether or not to output the control power output from the DC / DC converter 40 and the control battery 41 as a control voltage to the control voltage supply path 46 based on the input of the key switch 43 or the charge start switch 44.

[0034] When the cutoff switch 45 is switched to the cutoff position, the power supplied from the DC / DC converter 40 and the control battery 41 to the vehicle controller relay 42 is cut off, and the supply of control voltage to the control voltage supply path 46 is cut off.

[0035] The control voltage supply path 46 is connected to the vehicle body controller 50, the BMU 70a of the drive battery 70, the power converter 90, the inverter 60, and the signal circuit 100c3 of the control power judgment relay 100c, and guides the control voltage supplied from the control battery 41 to these electrical circuit devices via the vehicle body controller relay 42.

[0036] Figure 2 shows the circuit configuration of the relay 42 for the vehicle body controller.

[0037] The vehicle controller relay 42 includes a first relay 42a that operates when the key switch 43 is turned ON, and a second relay 42b that is connected in parallel to the first relay 42a and operates when the charging start switch 44 is turned ON.

[0038] The first relay 42a has a first switch section 42a1 and a first control coil section 42a2. The first switch section 42a1 is provided between the power line 41a connected to the positive terminals of the DC / DC converter 40 and the control battery 41, respectively, and the control voltage supply path 46. The first control coil section 42a2 is provided in the circuit 42G that grounds the power line 41a.

[0039] Similarly, the second relay 42b also has a second switch section 42b1 and a second control coil section 42b2, the second switch section 42b1 is provided between the power line 41a and the control voltage supply path 46, and the second control coil section 42b2 is provided in the circuit 42G that grounds the power line 41a.

[0040] Furthermore, a key switch 43 is provided on the branch line 41a1 that connects the power line 41a to the first control coil section 42a2, and a charging start switch 44 is provided on the branch line 41a2 that connects the power line 41a to the second control coil section 42b2.

[0041] When the key switch 43 and the charging start switch 44 are both in the off position, no current flows through the first and second control coil sections 42a2 and 42b2, so the first and second switch sections 42a1 and 42b1 are held in the off position, and no control voltage is output to the control voltage supply path 46. When the key switch 43 is turned ON and switched to the connected position, current flows through the first control coil section 42a2, the first switch section 42a1 switches to the connected position, and a control voltage is supplied to the control voltage supply path 46. Similarly, when the charging start switch 44 is turned ON and switched to the connected position, current flows through the second control coil section 42b2, the second switch section 42b1 switches to the connected position, and a control voltage is supplied to the control voltage supply path 46.

[0042] ~Electric Hydraulic Work Machinery~ Figure 3 shows the external appearance of an electric hydraulic work machine equipped with the electric drive system of this embodiment. In this embodiment, the work machine is a hydraulic excavator, which is known as a construction machine.

[0043] In other words, the electric hydraulic work machine comprises a lower traveling body 201, an upper slewing body 202, and a swing-type front work implement 203, the front work implement 203 consisting of a boom 111, an arm 112, and a bucket 113. The lower traveling body is a tracked type that moves by driving the left and right tracks 114 and 115 by the rotation of left and right travel motors 3f and 3g. The upper slewing body 202 can rotate relative to the lower traveling body 201 by the rotation of a slewing motor 3d. The front work implement 204 is mounted relative to the upper slewing body 202 so as to be able to move up and down. The boom 111, arm 112, and bucket 113 of the front work implement 204 can rotate in the vertical direction by the extension and retraction of boom cylinder 3a, arm cylinder 3b, and bucket cylinder 3c.

[0044] The upper rotating body 202 is equipped with a driver's seat 122 and an operating lever device 124 for operating actuators. The upper rotating body 202 is also equipped with the aforementioned external power supply 92, AC box 100, power converter 90, drive battery 70, inverter 60, DC / DC converter 40, control battery 41, relay 42 for vehicle controller, vehicle controller 50, key switch 43, charging start switch 44, cutoff switch 45, electric motor 1, hydraulic pump 2, and control valve 4.

[0045] ~Operation~ The operation of this embodiment, configured as described above, will now be explained.

[0046] (a) When the vehicle is stopped The cutoff switch 45 is in the connected position, and control power is supplied from the control battery 41 to the vehicle controller relay 42. However, when the vehicle is out of service, the key switch 43 and the charging start switch 44 are not operated, so no control voltage is supplied to the control voltage supply path 46.

[0047] Since no control voltage is supplied to the control voltage supply path 46, no control voltage is supplied to the BMU 70a in the drive battery 70, the control power judgment relay 100c in the AC box 100, the power converter 90, the vehicle controller 50, or the inverter 60.

[0048] Since no control voltage is supplied to BMU70a, the pre-charge relay 70e, battery relays 70c and 70d all remain in the tripped position.

[0049] Since battery relays 70c and 70d are in the tripped position, power is not supplied from the drive battery 70 to the power supply paths +HV and -HV.

[0050] Furthermore, since no control voltage is supplied to the control power judgment relay 100c in the AC box 100, the control power judgment relay 100c is in the tripped position, and regardless of the operation of the voltage monitoring relay 100b, no power is supplied to the control coil section 100d2 of the external power relay 100d, and the external power relay 100d maintains the tripped position.

[0051] Since the external power relay 100d is in the tripped position, power lines L11, L21, and L31 are tripped, and power supplied from the external power supply 92 is not supplied to the power converter 90.

[0052] Since power is not supplied to the power supply lines +HV and -HV from either the drive battery 70 or the power converter 90, the inverter 60 does not operate, the motor 1 remains stopped, and the hydraulic pump 2 also remains stopped.

[0053] Since hydraulic pump 2 is stopped, boom cylinder 3a, arm cylinder 3b, and bucket cylinder 3c all remain stopped.

[0054] (b) When operating on power from the drive battery 70 The cutoff switch 45 is in the connected position, and control power is supplied from the control battery 41 to the relay 42 for the vehicle controller.

[0055] When the operator operates the key switch 43, the relay 42 for the vehicle controller is activated, and the control power supplied from the control battery 41 is supplied as a control voltage to the control voltage supply path 46.

[0056] The control voltage from the control voltage supply path 46 is supplied to the BMU 70a in the drive battery 70, the control power judgment relay 100c in the AC box 100, the power converter 90, the vehicle controller 50, and the inverter 60.

[0057] When a control voltage is supplied to the BMU 70a, if the status of the multiple battery modules 70b is not abnormal, the BMU 70a receives a command from the vehicle controller 50 and controls the pre-charge relay 70e, battery relays 70c and 70d, and finally switches the battery relays 70c and 70d to the connected position.

[0058] When battery relays 70c and 70d are connected, power from the drive battery 70 is supplied to the power supply paths +HV and -HV.

[0059] Furthermore, since a control voltage is supplied to the control power supply determination relay 100c of the AC box 100, the control power supply determination relay 100c switches to the connection position.

[0060] If power is not supplied from the external power supply 92, power will not be supplied from the external power supply 92 to the power converter 90, even if the control power supply determination relay 100c is switched to the connected position.

[0061] Since power is not supplied to the power converter 90, power is not supplied from the power converter 90 to the power supply lines +HV and -HV.

[0062] Furthermore, since a control voltage is also supplied to the inverter 60, the inverter 60 drives the electric motor 1 at a rotational speed corresponding to the command from the vehicle controller 50, based on the power supplied from the drive battery 70 to the power supply lines +HV and -HV.

[0063] When power is supplied from the external power supply 92, the voltage monitoring device 100a switches the voltage monitoring relay 100b to the connected position. As a result, the voltage from the external power supply 92 is supplied to the control coil section 100d2 of the external power relay 100d via the voltage monitoring relay 100b and the control power supply determination relay 100c, and the external power relay 100d is held in the connected position.

[0064] Since the external power relay 100d is held in the connected position, power is supplied from the external power supply 92 to the power converter 90, and power can be supplied from the power converter 90 to the power supply paths +HV and -HV.

[0065] The inverter 60 drives the electric motor 1 at a rotational speed corresponding to a command from the vehicle controller 50, based on the power supplied from the power converter 90 and the drive battery 70 to the power supply lines +HV and -HV.

[0066] The electric motor 1 drives the hydraulic pump 2, and pressurized oil is supplied to the boom cylinder 3a, arm cylinder 3b, and bucket cylinder 3c via the control valve 4.

[0067] (c) When charging the drive battery 70 with power from the external power supply 92 The cutoff switch 45 is in the connected position, and control power is supplied from the control battery 41 to the relay 42 for the vehicle controller.

[0068] When the operator activates the charging start switch 44, the relay 42 for the vehicle controller activates and supplies the control power supplied from the control battery 41 as a control voltage to the control voltage supply path 46.

[0069] The control voltage from the control voltage supply path 46 is supplied to the BMU 70a in the drive battery 70, the control power judgment relay 100c in the AC box 100, the power converter 90, the vehicle controller 50, and the inverter 60.

[0070] When a control voltage is supplied to the BMU 70a, if the status of the multiple battery modules 70b is not abnormal, the BMU 70a receives a command from the vehicle controller 50 and controls the pre-charge relay 70e, battery relays 70c and 70d, and finally switches the battery relays 70c and 70d to the connected position.

[0071] Battery relays 70c and 70d are connected, and the power supply lines +HV and -HV are connected to the battery module 70b of the drive battery 70.

[0072] Furthermore, since a control voltage is supplied to the control power supply determination relay 100c inside the AC box 100, the control power supply determination relay 100c switches to the connected position.

[0073] If the power supplied from the external power supply 92 is not at an abnormal voltage, and the voltage monitoring device 100a has switched the voltage monitoring relay 100b to the connected position, then the voltage of one of the three phases of the external power supply 92 is supplied to the control coil section 100d2 of the external power supply relay 100d via the voltage monitoring relay 100b and the control power supply determination relay 100c, and switches the external power supply relay 100d to the connected position.

[0074] Since the external power relay 100d is in the connection position, the power supplied from the external power supply 92 is directed to the power converter 90.

[0075] Since a control voltage is supplied to the power converter 90, the power converter 90 starts up and converts the three-phase AC power supplied from the external power supply 92 to DC as described above, and supplies it to the power supply lines +HV and -HV.

[0076] The power supply lines +HV and -HV are connected to the battery module 70b of the drive battery 70, and power is supplied from the power converter 90 to the power supply lines +HV and -HV, so the battery module 70b is charged with that power.

[0077] On the other hand, although control voltage is also supplied to the inverter 60, in this case the key switch 43 is not in the ON position, so the inverter 60 stops the motor 1.

[0078] Since hydraulic pump 2 is stopped, boom cylinder 3a, arm cylinder 3b, and bucket cylinder 3c all remain stopped.

[0079] (d) If the voltage of the external power supply becomes abnormally high during charging If, during charging, the voltage of the external power supply 92 becomes abnormal, and the voltage between, for example, the AC line L11 and the neutral line N among the power lines L11, L21, and L31 becomes abnormally high, the voltage monitoring device 100a switches the voltage monitoring relay 100b to the trip position.

[0080] As the voltage monitoring relay 100b is in the tripped position, power is no longer supplied to the control coil section 100d2 of the external power relay 100d, and the external power relay 100d switches from the connected position to the tripped position.

[0081] Since the external power relay 100d is in the tripped position, power lines L11, L21, and L31 are shut off, and power is not supplied from the external power supply 92 to the power converter 90.

[0082] Since power is not supplied to the power converter 90, power is not supplied from the power converter 90 to the power supply lines +HV and -HV, and power is not supplied to the inverter 60 either.

[0083] In this way, if the voltage of the external power supply 92 is abnormal, the voltage monitoring device 100a and voltage monitoring relay 100b of the tripping control device 120 will activate, and the external power relay 100d will switch to the tripping position, thereby preventing abnormal voltage from being transmitted to the power converter 90 and preventing damage to the power converter 90.

[0084] (e) When performing maintenance on electrical circuit equipment When performing maintenance on electrical circuit equipment, the operator switches the disconnect switch 45 to the disconnect position. When the disconnect switch 45 is switched to the disconnect position, the supply of control power from the DC / DC converter 40 and the control battery 41 to the vehicle controller relay 42 is stopped.

[0085] Since control power is not supplied to the relay 42 for the vehicle controller, even if the key switch 43 and the charging start switch 44 are activated, control voltage is not supplied to the control voltage supply path 46.

[0086] Since no control voltage is supplied to the control voltage supply path 46, no control voltage is supplied to the BMU 70a in the drive battery 70, the control power judgment relay 100c in the AC box 100, the power converter 90, the vehicle controller 50, or the inverter 60.

[0087] Since no control voltage is supplied to BMU70a, the pre-charge relay 70e, battery relays 70c and 70d all remain in the tripped position.

[0088] Since battery relays 70c and 70d are in the tripped position, power is not supplied from the drive battery 70 to the power supply paths +HV and -HV.

[0089] Furthermore, since no control voltage is supplied to the control power judgment relay 100c in the AC box 100, the control power judgment relay 100c of the tripping control device 120 is in the tripped position. Regardless of the operation of the voltage monitoring relay 100b, no power is supplied to the control coil section 100d2 of the external power relay 100d, and the external power relay 100d maintains the tripped position.

[0090] Since the external power relay 100d is in the tripped position, power lines L11, L21, and L31 are tripped, and no power is supplied from the external power supply 92 to the power converter 90. Also, no power is supplied to power lines L12, L22, L32 and the neutral line N2 between the AC box 100 and the power converter 90.

[0091] Furthermore, since control voltage is not supplied to the power converter 90 and inverter 60, neither the power converter 90 nor the inverter 60 operates.

[0092] Since power is not supplied from the drive battery 70 to the power supply lines +HV and -HV, and the inverter 60 does not operate, the electric motor 1 remains stopped, and the hydraulic pump 2 also remains stopped.

[0093] Since hydraulic pump 2 is stopped, boom cylinder 3a, arm cylinder 3b, and bucket cylinder 3c all remain stopped.

[0094] In this way, simply by switching the cutoff switch 45, which cuts off the power to the control battery 41, to the cutoff position, the power supply judgment relay 120c of the cutoff control device 120 cuts off the power supplied from the drive battery 70 and the external power supply 92, which are power supply sources. Therefore, when performing maintenance on electrical circuit equipment (power converter 90, inverter 60, vehicle controller 50, vehicle controller relay 42, DC / DC converter 40, etc.), simply by operating the cutoff switch 45, the power supply from both the drive battery 70 and the external power supply 92 is cut off, allowing for electrically safe maintenance work with simple operation.

[0095] ~Effects~ According to this embodiment, the following effects can be obtained.

[0096] (1) If the voltage of the external power supply 92 is abnormal, the tripping control device 120 will activate and the external power relay 100d will switch to the tripping position, thereby preventing abnormal voltage from being transmitted to the power converter 90 and preventing damage to the power converter 90.

[0097] (2) By simply switching the cutoff switch 45, which cuts off the power to the control battery 41, to the cutoff position, the power supply from the drive battery 70 and the external power supply 92, which are power supply sources, is cut off by the cutoff control device 120. Therefore, when performing maintenance on electrical circuit equipment (power converter 90, inverter 60, vehicle controller 50, relay for vehicle controller 42, DC / DC converter 40, etc.), simply by operating the cutoff switch 45, the power supply from both the drive battery 70 and the external power supply 92 is cut off, allowing for electrically safe maintenance work to be performed with simple operation.

[0098] <Second Embodiment> Figure 4 shows the overall configuration of the electric drive system for an electric work machine in a second embodiment of the present invention.

[0099] In Figure 4, the AC box 100 of the electric drive system in this embodiment, like the interruption control device 120 of the first embodiment, has an interruption control device 130 that switches the external power relay 100d from the connected position to the interrupted position and interrupts the power lines L11, L21, and L31 when a voltage abnormality occurs in the external power supply 92 or when the control voltage is interrupted by the interruption switch 45.

[0100] In the first embodiment, the AC box 100's cutoff control device 120 is configured with a voltage monitoring device 100a, a voltage monitoring relay 100b, and a control power supply determination relay 100c. When a voltage abnormality occurs in the external power supply 92, or when the control voltage is cut off by the cutoff switch 45, the external power supply relay 100d is switched to the cutoff position, cutting off the power lines L11, L21, L31 and the neutral line N1.

[0101] In this embodiment, the voltage control device 130 of the AC box 100 is configured with a voltage monitoring device 100e and a voltage monitoring relay 100f. The voltage monitoring device 100e monitors both voltage abnormalities of the external power supply 92 and the interruption of the control voltage. In the event of a voltage abnormality in the external power supply 92 or an interruption of the control voltage by the interruption switch 45, the external power relay 100d is switched from the connected position to the interrupted position, thereby interrupting the power lines L11, L21, and L31.

[0102] More specifically, in Figure 4, the circuit breaker control device 130 of the AC box 100 in this embodiment has a voltage monitoring device 100e and a voltage monitoring relay 100f. The control coil section 100d2 of the external power relay 100d is connected to the three-phase AC line L11, which is one of the power lines L11, L21, and L31, via the switch section 100f1 of the voltage monitoring relay 100f. The switch section 100f1 of the voltage monitoring relay 100f is connected between the three-phase AC line L11 and the control coil section 100d2 of the external power relay 100d. As a result, when the switch section 100f1 of the voltage monitoring relay 100f is switched to the circuit breaker position, the switch section 100d1 of the external power relay 100d is also switched to the circuit breaker position.

[0103] Furthermore, the control coil section 100f2 of the voltage monitoring relay 100f is connected to the signal circuit 100e1 of the voltage monitoring device 100e. When the voltage monitoring device 100e detects a voltage abnormality, it outputs a control voltage to the signal circuit 100e1 and switches the switch section 100f1 of the voltage monitoring relay 100f from the connected position to the disconnected position.

[0104] Furthermore, the voltage monitoring device 100e is also connected to the control voltage supply path 46 via the signal circuit 100e2. When it detects that the control voltage has been cut off by the cutoff switch 45, it outputs the control voltage to the signal circuit 100e1 and switches the switch section 100f1 of the voltage monitoring relay 100f from the connected position to the cutoff position.

[0105] As a result, the tripping control device 130 switches the external power relay 100d from the connected position to the tripped position when the voltage monitoring device 100e detects a voltage abnormality in the external power supply 92, or when it detects that the control voltage has been cut off by the tripping switch 45.

[0106] In this embodiment, the same effects as in the first embodiment can be obtained. Furthermore, in this embodiment, since the only signal circuit equipped with a relay is the signal circuit 100e1, the circuit configuration is simpler, and an inexpensive system configuration can be achieved.

[0107] <Other> In the embodiments described above, the case where the electric work machine is a tracked hydraulic excavator has been explained, but the work machine may be a work machine other than a tracked hydraulic excavator (for example, a wheeled hydraulic excavator, hydraulic crane, wheel loader, etc.). [Explanation of Symbols]

[0108] 1 electric motor 2. Hydraulic pump 10A Hydraulic Drive System 10B Power Supply System 30 Control Power System 40 DC / DC Converters 41. Control battery (control power supply) 42 Relay for vehicle controller 43 key switches 44 Charging Start Switch 45. Disconnection switch 46 Control voltage supply path 50 Vehicle Controller 60 Inverters 65 Junction Box 70 Power battery (internal battery) 70a BMU 70b Battery Module 70c, 70d Battery Relay 70e Precharge Relay 70f precharge resistor 90 Power converter 92 Three-phase AC power supply 92 (external power supply) 100 AC Box (External Power Connection Device) 100A Voltage Monitoring Device (Trip-off Control Device) 100b Voltage monitoring relay (trip control device) 100b1 Switch section 100b2 Control coil section 100c Control Power Judgment Relay (Turnoff Control Device) 100c1 Switch Unit 100c2 Control Coil Section 100d External Power Relay 100d1 Switch section 100d2 Control coil section 100e Voltage Monitoring Device (Trip Control Device) 100F Voltage Monitoring Relay (Trip Control Device) 100f1 Switch section 100f2 Control Coil Section 120,130 Interruption control device L11, L21, L31 Three-phase AC line (power line) N1 neutral line

Claims

1. An electric motor for generating driving power; An inverter that drives the electric motor; an internal battery that supplies power to the inverter for driving the motor; An external power supply connection device; a power conversion device connected to the external power supply connection device and configured to rectify power supplied from an external power supply to generate power for charging the internal battery; In an electric drive system for an electric working machine including the inverter and a control power supply that supplies a control voltage to the power conversion device via a control voltage supply path, a cutoff switch that cuts off the supply of the control voltage from the control power supply, The external power supply connection device includes: a power line connecting the external power source and the power conversion device; an external power relay connected to the power line and switching from a connection position to a disconnection position to disconnect the power line; an interruption control device connected to the power line and the control voltage supply path, and switching the external power supply relay to an interrupt position and interrupting the power line when a voltage abnormality occurs in the external power supply or when the control voltage is interrupted by the interruption switch.

2. The electric drive system for an electric working machine according to claim 1, the external power supply relay is configured to be switched from a cut-off position to a connect position when power is supplied from the external power supply, The cut-off control device cuts off the supply of power from the external power source to the external power source relay when a voltage abnormality occurs in the external power source or when the control voltage is cut off by the cut-off switch.

3. The electric drive system for an electric working machine according to claim 2, The shutoff control device includes: a voltage monitoring device connected to the power line and monitoring a voltage abnormality of the external power supply; a voltage monitoring relay that switches to a cut-off position when the voltage monitoring device detects a voltage abnormality in the external power supply, thereby cutting off the supply of power from the external power supply to the external power supply relay and switching the external power supply relay to the cut-off position; a control power supply determination relay connected to the control voltage supply path and switching to a cut-off position when the control voltage is cut off by the cut-off switch, thereby cutting off the supply of power from the external power source to the external power supply relay and switching the external power supply relay to the cut-off position.

4. The electric drive system for an electric working machine according to claim 3, An electric drive system for an electric working machine, characterized in that a switch section of the voltage monitoring relay and a switch section of the control power supply determination relay are connected in series between the power line and a control coil section of the external power supply relay.

5. The electric drive system for an electric working machine according to claim 1, The shutoff control device includes: a voltage monitoring device connected to the power line and the control power supply, and monitoring a voltage abnormality of the external power supply and interruption of the control voltage by the interrupter switch; and a voltage monitoring relay that switches to a cut-off position when the voltage monitoring device detects a voltage abnormality in the external power supply or when the cut-off switch detects that the control voltage has been cut off, thereby cutting off the supply of power from the external power supply to the external power supply relay and switching the external power supply relay to the cut-off position.

6. The electric drive system for an electric working machine according to claim 5, 13. An electric drive system for an electric working machine, comprising: a switch portion of the voltage monitoring relay connected between the power line and a control coil portion of the external power supply relay.

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