JP7321711B2 - working machine - Google Patents

Description

The present invention relates to work machines.

2. Description of the Related Art Conventionally, a working machine is known in which a hydraulic pump that supplies hydraulic fluid to a hydraulic actuator can be driven by a plurality of driving means such as an electric motor and other driving means (eg, engine) (see, for example, Patent Document 1).

JP 2013-028962 A

By the way, instead of installing a sensor for detecting the rotation angle of the electric motor, sensorless control technology that controls the electric motor while estimating the rotation angle may be applied to work machines.

However, when the sensorless control technology is used, the initial position of the rotation angle of the motor when the servo of the motor is turned on must be known. Therefore, the initial position of the rotation angle is normally detected while the other drive means and the hydraulic pump are not rotating, that is, the electric motor is not rotated by the action of the other drive means. This is because when the motor is rotating, the induced voltage of the motor cannot be ignored, and the rotation angle cannot be detected using changes in the winding inductance. Therefore, for example, when the work machine is started, although the hydraulic pump can be started by other driving means, it is necessary to wait for the start of the hydraulic pump until the end of the detection process of the initial value of the rotation angle. It may take a relatively long time to start.

Therefore, in view of the above problems, it is an object of the present invention to provide a working machine capable of improving work efficiency when sensorless control of an electric motor that drives a hydraulic pump is employed.

To achieve the above object, in one embodiment of the present invention,
a hydraulic actuator;
a hydraulic pump that supplies hydraulic fluid to the hydraulic actuator;
an electric motor that drives the hydraulic pump;
another driving means for driving the hydraulic pump;
a control device that estimates a rotation angle of the electric motor and controls the electric motor based on the estimated rotation angle;
Until the error between the estimated value and the actual value of the rotation angle converges, or until the current value of the electric motor is suppressed below a predetermined threshold, the rotation of the hydraulic pump by the other drive means intermittently energizing the electric motor while the electric motor is being rotated accordingly;
A working machine is provided.

According to the above-described embodiment, it is possible to provide a work machine capable of improving work efficiency when sensorless control of an electric motor that drives a hydraulic pump is employed.

It is a side view of a shovel. It is a block diagram showing an example of composition of a shovel roughly. FIG. 10 is a sequence diagram showing the operation of the shovel according to the comparative example when it is started. FIG. 4 is a sequence diagram showing the operation of the shovel according to one embodiment when it is started. 4 is a flowchart schematically showing an example of servo start control processing by an inverter (control circuit); FIG. 4 is a diagram showing temporal changes in various states corresponding to the operation when the shovel according to one embodiment is started.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.

[Overview of Excavator]
First, an outline of a shovel as an example of a working machine will be described with reference to FIG.

FIG. 1 is a side view showing an example of a shovel according to this embodiment.

An excavator (an example of a working machine) according to the present embodiment includes a lower traveling body 1, an upper revolving body 3 mounted on the lower traveling body 1 so as to be able to turn via a revolving mechanism 2, a boom 4 as a working device, It has an arm 5, a bucket 6, and a cabin 10 in which an operator boards.

The lower traveling body 1 includes, for example, a pair of left and right crawlers, and the respective crawlers are hydraulically driven by traveling hydraulic motors 1A and 1B (see FIG. 2) to self-propell.

The upper revolving body 3 revolves with respect to the lower traveling body 1 by electrically driving the revolving mechanism 2 by a revolving electric motor 21 (see FIG. 2), which will be described later.

The boom 4 is pivotally attached to the center of the front portion of the upper rotating body 3 so as to be able to be raised. An arm 5 is pivotally attached to the tip of the boom 4 so as to be vertically rotatable. rotatably pivoted; The boom 4, arm 5, and bucket 6 are hydraulically driven by boom cylinders 7, arm cylinders 8, and bucket cylinders 9 as hydraulic actuators, respectively.

The cabin 10 is mounted on the front left side of the upper swing body 3, and is provided with a cockpit on which an operator is seated, an operation device 26 described later, and the like.

[Excavator configuration]
Next, the configuration of the excavator according to the present embodiment will be described with reference to FIG. 2 in addition to FIG.

FIG. 2 is a block diagram showing an example of the configuration centering on the drive system of the excavator according to the present embodiment.

In the figure, mechanical power lines are indicated by double lines, high-pressure hydraulic lines are indicated by thick solid lines, pilot lines are indicated by broken lines, and electric drive/control lines are indicated by thin solid lines.

<Excavator hydraulic drive system>
As described above, the hydraulic drive system of the excavator according to the present embodiment includes traveling hydraulic motors 1A and 1B, a boom cylinder 7, an arm cylinder 8, which hydraulically drive the lower traveling body 1, the boom 4, the arm 5, and the bucket 6, respectively. , and hydraulic actuators such as bucket cylinders 9 . Further, the hydraulic drive system according to this embodiment mainly includes an engine 11 , a motor generator 12 , a speed reducer 13 , a main pump 14 and a control valve 17 .

The motor generator 12 will be described in detail in the description of the electric drive system of the excavator.

The engine 11 (an example of another driving means) is the main power source in the hydraulic drive system and is mounted on the rear portion of the upper swing body 3 . The engine 11 rotates at a predetermined target rotation speed under the control of an engine controller (ECM: Engine Control Module) 30C, which will be described later. The engine 11 is, for example, a diesel engine using light oil as fuel, and drives a main pump 14 and a pilot pump 15 via a reduction gear 13 . In addition, the engine 11 drives the motor generator 12 via the reduction gear 13 to cause the motor generator 12 to generate electricity.

The speed reducer 13 is mounted, for example, on the rear portion of the upper swing body 3, and is coaxially connected in series with two input shafts to which the engine 11 and a motor generator 12 (to be described later) are connected, a main pump 14, and a pilot pump 15. It has one output shaft. The reduction gear 13 can transmit the power of the engine 11 and the motor generator 12 to the main pump 14 and the pilot pump 15 at a predetermined reduction ratio. Further, the reduction gear 13 can distribute and transmit the power of the engine 11 to the motor generator 12, the main pump 14, and the pilot pump 15 at a predetermined reduction ratio.

A main pump 14 (an example of a hydraulic pump) is mounted on the rear portion of the upper rotating body 3 and supplies hydraulic oil to control valves 17 through high-pressure hydraulic lines 16 . The main pump 14 is driven by the engine 11 or by the engine 11 and the motor generator 12 . The main pump 14 is, for example, a variable displacement hydraulic pump, and a regulator (not shown) controls the angle (tilt angle) of the swash plate under the control of a shovel controller 30A, which will be described later. Thereby, the main pump 14 can adjust the stroke length of the piston and control the discharge flow rate (discharge pressure).

The control valve 17 is a hydraulic control device that is mounted in the central portion of the upper revolving body 3 and that controls the hydraulic drive system according to the operation of the operating device 26 by the operator. As described above, the control valve 17 is connected to the main pump 14 via the high-pressure hydraulic line 16, and supplies hydraulic fluid supplied from the main pump 14 to the traveling hydraulic motors 1A (for right) and 1B (for left) as hydraulic actuators. ), boom cylinder 7 , arm cylinder 8 , and bucket cylinder 9 . Specifically, the control valve 17 is a valve unit that includes a plurality of hydraulic control valves (directional switching valves) that control the flow rate and flow direction of hydraulic oil supplied from the main pump 14 to each hydraulic actuator.

<Excavator electric drive system>
The electric drive system of the excavator according to this embodiment includes a motor-generator 12, a current sensor 12s1, a voltage sensor 12s2, and an inverter 18A as components that assist the hydraulic drive system. In addition, the electric drive system of the excavator according to the present embodiment includes a turning electric motor 21, a current sensor 21s, and a resolver 22 as components related to electric driving of the driven element (specifically, the upper turning body 3). , a mechanical brake 23, a turning speed reducer 24, and an inverter 18B.

A motor-generator 12 (an example of an electric motor) is an assist power source for the hydraulic drive system and is mounted on the rear part of the upper revolving body 3 . The motor generator 12 is, for example, an IPM (Interior Permanent Magnet) motor. The motor generator 12 is connected to a power storage system 120 including a capacitor 19 and the turning motor 21 via an inverter 18A. The motor-generator 12 is powered by three-phase AC power supplied from the capacitor 19 and the turning electric motor 21 via the inverter 18A, and assists the engine 11. Drive the pump 15 . Further, the motor generator 12 is driven by the engine 11 to perform power generation operation, and can supply the generated power to the capacitor 19 and the turning motor 21 . Switching control between the power running operation and the power generation operation of the motor generator 12 may be realized by the inverter 18A under the control of a hybrid controller (hereinafter referred to as "HB controller") 30B, which will be described later.

The current sensor 12s1 detects the current of each of the three phases (U-phase, V-phase, W-phase) of the motor generator 12 . The current sensor 12s1 is provided, for example, in the power path between the motor generator 12 and the inverter 18A. A detection signal corresponding to each of the three-phase currents of the turning electric motor 21 detected by the current sensor 12s1 is directly input to the inverter 18A through a one-to-one communication line or an in-vehicle network such as a CAN (Controller Area Network). Alternatively, the detection signal may be once taken into the HB controller 30B through a one-to-one communication line or an in-vehicle network such as CAN, and then inputted to the inverter 18A via the HB controller 30B. The same applies to the detection signal of the voltage sensor 12s2.

The voltage sensor 12 s 2 detects the voltage applied to each of the three phases of the motor generator 12 . The current sensor 21s is provided, for example, in the power path between the motor generator 12 and the inverter 18A. A detection signal corresponding to the applied voltage of each of the three phases of the turning electric motor 21 detected by the voltage sensor 12s2 is directly taken into the inverter 18A through a one-to-one communication line or an in-vehicle network such as CAN.

The inverter 18A (an example of a control device) drives and controls the motor generator 12 under the control of the HB controller 30B. The inverter 18A defines, for example, a conversion circuit that converts DC power into three-phase AC power or converts three-phase AC power into DC power, a drive circuit that switches the conversion circuit, and the operation of the drive circuit. and a control circuit that outputs a control signal (for example, a PWM (Pulse Width Modulation) signal).

Specifically, the control circuit of the inverter 18A may sequentially estimate the rotation angle of the rotating shaft of the motor generator 12 based on the detection signals of the current sensor 12s1 and the voltage sensor 12s2. For example, the control circuit estimates the rotation angle, rotation speed, etc. of the rotation shaft of the motor generator 12 based on, for example, a known extended electromotive force (EEFM) model. Then, the control circuit controls the drive of the motor generator 12 (hereinafter referred to as "sensorless control") while grasping the operating state of the motor generator 12 based on the estimated values of the rotation angle and rotation speed that are sequentially derived. you can go As a result, the motor generator 12 does not need to be provided with a predetermined sensor (for example, a rotary encoder or the like) for detecting the rotation angle and rotation position. Therefore, the number of mechanical sensors can be reduced, the cost of the excavator can be suppressed, and detection failure due to contamination of the sensor can be suppressed.

The control circuit of the inverter 18A is input from the HB controller 30B instead of the detected value of the applied voltage of the motor generator 12 by the voltage sensor 12s2, or the voltage of the motor generator 12 generated in the process of its own control. The rotation angle of the rotating shaft of the motor generator 12 and the like may be estimated using the voltage command value. In this case, the voltage sensor 12s2 can be omitted. At least one of the drive circuit and the control circuit of the inverter 18A may be provided outside the inverter 18A (for example, the HB controller 30B (an example of a control device)).

The turning electric motor 21 is provided in the turning mechanism 2 that connects the lower traveling body 1 and the upper turning body 3. Under the control of the HB controller 30B, the turning electric motor 21 is powered to drive the upper turning body 3 to turn, and regenerative power. is generated to perform regenerative operation in which the upper swing body 3 is swing-braked. The turning electric motor 21 is connected to the power storage system 120 via the inverter 18B, and is driven by three-phase AC power supplied from the capacitor 19 and the motor generator 12 via the inverter 18B. In addition, the turning electric motor 21 supplies regenerated electric power to the capacitor 19 and the motor generator 12 via the inverter 18B. As a result, the regenerated power can be used to charge the capacitor 19 and drive the motor generator 12 . Switching control between the power running operation and the regenerative operation of the turning electric motor 21 may be realized by the inverter 18B under the control of the HB controller 30B. A resolver 22 , a mechanical brake 23 , and a turning speed reducer 24 are connected to the rotating shaft 21</b>A of the turning electric motor 21 .

The current sensor 21s detects the current of each of the three phases (U-phase, V-phase, W-phase) of the electric motor 21 for turning. The current sensor 21s is provided, for example, in the electric power path between the turning electric motor 21 and the inverter 18B. A detection signal corresponding to each of the three-phase currents of the turning electric motor 21 detected by the current sensor 21s is directly taken into the inverter 18B through a one-to-one communication line or an in-vehicle network such as CAN. Alternatively, the detection signal may be once taken into the HB controller 30B through a one-to-one communication line or an in-vehicle network such as CAN, and may be inputted to the inverter 18B via the HB controller 30B. The same applies to the detection signals of the resolver 22 below.

The resolver 22 detects the rotational position (rotational angle) and the like of the turning electric motor 21 . A detection signal corresponding to the rotation angle detected by the resolver 22 is directly taken into the inverter 18B through a one-to-one communication line, an in-vehicle network such as CAN, or the like.

The mechanical brake 23 mechanically generates a braking force to the rotating shaft 21A of the turning electric motor 21 under the control of the HB controller 30B. As a result, the mechanical brake 23 can perform swing braking of the upper swing body 3 and maintain the stopped state of the upper swing body 3 .

The turning speed reducer 24 is connected to the rotating shaft 21A of the turning electric motor 21, and reduces the output (torque) of the turning electric motor 21 at a predetermined reduction ratio to increase the torque and turn the upper turning body 3. drive. That is, during the power running operation, the turning electric motor 21 drives the upper turning body 3 to turn through the turning speed reducer 24 . Further, the turning speed reducer 24 accelerates the inertia rotational force of the upper turning body 3 and transmits it to the turning electric motor 21 to generate regenerative electric power. That is, during regenerative operation, the turning electric motor 21 regeneratively generates power by the inertia rotational force of the upper turning body 3 transmitted through the turning speed reducer 24 , and brakes the turning of the upper turning body 3 .

The inverter 18B drives and controls the turning electric motor 21 under the control of the HB controller 30B. The inverter 18B, for example, defines a conversion circuit that converts DC power into three-phase AC power or converts three-phase AC power into DC power, a drive circuit that switch-drives the conversion circuit, and the operation of the drive circuit. and a control circuit that outputs a control signal (for example, a PWM signal) to

Specifically, the control circuit of the inverter 18B performs speed feedback control and torque feedback control on the turning electric motor 21 based on detection signals from the current sensor 21s and the resolver 22 .

<Excavator power storage system>
A power storage system 120 of the excavator according to this embodiment includes a capacitor 19 , a buck-boost converter 100 , and a DC bus 110 . The power storage system 120 is mounted, for example, on the front right portion of the upper revolving body 3 together with the inverters 18A and 18B of the electric drive system.

The capacitor 19 is an example of a power storage device that supplies electric power to the motor generator 12 and the turning electric motor 21 and charges the electric power generated by the motor generator 12 and the turning electric motor 21 . In addition, a relay (hereinafter referred to as “interruption relay”) is provided to disconnect between the capacitor 19 and the main circuit on the load side including the step-up/step-down converter 100 . As a result, the capacitor 19 is disconnected from the main circuit under the control of the HB controller 30B when the excavator stops or malfunctions (for example, when an accident such as overturning occurs). Therefore, it is possible to prevent a situation in which a very large short-circuit current flows through the capacitor 19 due to an abnormality in the absence of the operator or an abnormality in the presence of the operator. The cut-off relays are provided, for example, in both positive and negative power paths between the capacitor 19 and the step-up/step-down converter 100 .

The step-up/step-down converter 100 steps up the power of the capacitor 19 and outputs it to the DC bus 110 , or steps down the power supplied to the DC bus 110 and causes the capacitor 19 to store the power. The step-up/step-down converter 100 switches between a step-up operation and a step-down operation according to the operating states of the motor generator 12 and the turning electric motor 21 so that the voltage value of the DC bus 110 falls within a certain range. The switching control between the step-up operation and the step-down operation of the buck-boost converter 100 may be realized by the HB controller 30B based on the voltage detection value of the DC bus 110, the voltage detection value of the capacitor 19, and the current detection value of the capacitor 19.

The DC bus 110 is provided between the inverters 18A, 18B and the step-up/down converter 100, and controls the transfer of electric power among the capacitor 19, the motor generator 12, and the electric motor 21 for turning.

<Excavator operation system>
Further, the operating system of the excavator according to this embodiment includes the pilot pump 15, the operating device 26, the pressure sensor 29, and the like.

The pilot pump 15 is mounted on the rear part of the upper revolving body 3 and supplies pilot pressure to the operating device 26 via the pilot line 25 . The pilot pump 15 is, for example, a fixed displacement hydraulic pump, and is driven by the engine 11 or by the engine 11 and the motor generator 12 .

The operating device 26 includes, for example, levers 26A and 26B and pedals 26C. The operation device 26 is provided near the cockpit of the cabin 10, and the operator operates each driven element (eg, the lower traveling body 1, the upper rotating body 3, the boom 4, the arm 5, the bucket 6, etc.). It is an operation input means for In other words, the operation device 26 includes hydraulic actuators (for example, traveling hydraulic motors 1A and 1B, boom cylinder 7, arm cylinder 8, bucket cylinder 9, etc.) and electric actuators (swing electric motor 21) that drive respective driven elements. etc.). An operating device 26 (levers 26A, 26B and pedals 26C) is connected to the control valve 17 via a hydraulic line 27. As shown in FIG. As a result, a pilot signal (pilot pressure) is input to the control valve 17 according to the operation state of the lower traveling body 1, the boom 4, the arm 5, the bucket 6, and the like in the operation device 26. FIG. Therefore, the control valve 17 can drive each hydraulic actuator according to the operating state of the operating device 26 . The operating device 26 is also connected to a pressure sensor 29 via a hydraulic line 28 .

The pressure sensor 29 is connected to the operating device 26 via the hydraulic line 28 as described above, and detects the pilot pressure on the secondary side of the operating device 26, that is, the pilot pressure corresponding to the operating state of each driven element in the operating device 26. Detect pressure. The pressure sensor 29 is connected to the excavator controller 30A, and the detection signal (pressure detection value) corresponding to the operation state of the lower traveling body 1, upper rotating body 3, boom 4, arm 5, bucket 6, etc. in the operating device 26 is , is taken into the excavator controller 30A.

<Excavator control system>
The excavator control system according to the present embodiment includes a control device 30 , a starter motor 11st and an HMI (Human Machine Interface) 50 .

The control device 30 includes an excavator controller 30A, an HB controller 30B, and an engine controller 30C.

The functions of the excavator controller 30A, the HB controller 30B, the engine controller 30C, and the like may be realized by arbitrary hardware or a combination of hardware and software. For example, the excavator controller 30A, the HB controller 30B, the engine controller 30C, and the like include a CPU (Central Processing Unit), a memory device (main storage device) such as a RAM (Random Access Memory), and a ROM (Read Only Memory). It may be configured around a microcomputer including a non-volatile auxiliary storage device and an I/O (Input-Output) interface device.

The excavator controller 30A cooperates with various controllers including the HB controller 30B and the engine controller 30C, and performs drive control of the excavator. For example, the excavator controller 30A may integrally control the operation of the entire excavator (various devices mounted on the excavator) based on two-way communication with various controllers such as the HB controller 30B and the engine controller 30C.

The HB controller 30B performs drive control of the electric drive system based on various information input from the excavator controller 30A (for example, control commands including detection values of the pressure sensor 29 corresponding to the operating state of the operating device 26). For example, the HB controller 30B drives the inverter 18A based on the detected value corresponding to the operation state of the operation device 26 detected by the pressure sensor 29, and changes the operation state (power running operation and power generation operation) of the motor generator 12. Perform switching control. Further, for example, the HB controller 30B drives the inverter 18B based on the detected value corresponding to the operation state of the operation device 26 detected by the pressure sensor 29, and controls the operation state (power running and regenerative operation) of the turning electric motor 21. ) is controlled. Further, for example, the HB controller 30B drives the buck-boost converter 100 based on the detected value corresponding to the operation state of the operation device 26 detected by the pressure sensor 29, and In other words, switching control between the discharging state and the charging state of the capacitor 19 is performed.

Further, the HB controller 30B may have a self-diagnostic function for the electric drive system and detect various abnormalities regarding the electric drive system.

Specifically, the HB controller 30B may detect an abnormality in the motor generator 12 or an abnormality in the inverter 18A, that is, an abnormality in the motor generator 12 . For example, the HB controller 30B detects abnormal temperature, abnormal current (eg, overcurrent), abnormal voltage (eg, overvoltage), etc. by monitoring the temperature, current, voltage, etc. of the motor generator 12 and the inverter 18A. you can Also, the HB controller 30B may detect an abnormality of components such as semiconductor switches, resistors, capacitors, and diodes of the inverter 18A.

The engine controller 30C drives the engine 11 based on various information input from the excavator controller 30A (for example, a control command including a set rotational speed of the engine 11 and an operation mode of the excavator corresponding to the set rotational speed of the engine 11). control. Specifically, the engine controller 30</b>C realizes drive control of the engine 11 by outputting control commands to actuators such as the starter motor 11st and the fuel injection device of the engine 11 to be controlled.

The engine controller 30C may also have a self-diagnostic function for the engine 11 and detect various abnormalities regarding the engine 11 . For example, the engine controller 30C may detect an abnormality in various actuators such as the fuel injection device of the engine 11, an abnormality in various sensors such as a crank angle sensor, an abnormality in the exhaust system, and the like.

The starter motor 11st is powered by an auxiliary battery (for example, a lead-acid battery) (not shown), and forcibly rotates the crankshaft of the engine 11 to start the engine 11 under the control of the engine controller 30C. Specifically, the starter motor 11st starts the engine 11 by assisting the engine 11 with a degree of assistance relatively smaller than that of the motor generator 12 .

The HMI 50 is provided inside the cabin 10 and has an interface function between the operator and the excavator. The HMI 50 includes notification (display) means (for example, instrument panel and display including warning lights, etc.), operation means (for example, operation device 26, display touch panel, various buttons, switches, toggles, etc. arranged around the cockpit). )including.

[Specific example of motor generator control method]
Next, with reference to FIGS. 3 and 4 (FIGS. 4A to 4C), a specific example of a control method for the motor-generator 12 by the inverter 18A will be described.

<Method for controlling motor generator according to comparative example>
First, with reference to FIG. 3, a method of controlling the motor generator by the inverter 18Ac of the excavator according to the comparative example will be described.

FIG. 3 is a diagram for explaining the operation of the shovel according to the comparative example when it is started. Specifically, FIG. 3 is a sequence diagram showing an example of the operation when the shovel according to the comparative example is started.

The inverter 18Ac, the engine controller 30Cc, and the HMI 50c of the excavator according to the comparative example are components corresponding to the inverter 18A, the engine controller 30C, and the HMI 50 of the excavator according to the present embodiment, respectively.

As shown in FIG. 3, in step S102, the operator performs a key operation on the HMI 50c (eg, key cylinder, etc.).

At step S104, the HMI 50c turns on the key switch according to the operator's key operation. As a result, the power supply to the inverter 18Ac, the engine controller 30C, etc. is started.

Specifically, when the key switch is turned on, the controller of the electric drive system corresponding to the HB controller of the present embodiment is started, and when the controller turns on the power switch of the electric drive system, , the power supply to the inverter 18A may be started. Hereinafter, the same applies to the case of step S204 in FIG. 4A.

In step S106, the inverter 18Ac detects the initial position of the rotation angle of the motor generator (hereinafter, "initial rotation angle") immediately after its activation. Specifically, the inverter 18Ac may detect the initial rotation angle based on the winding inductance of the motor generator in the stopped state.

In step S108, the inverter 18Ac transmits an engine start permission notice to the engine controller 30Cc upon completion of the detection of the initial rotation angle of the motor generator. At this time, the notification of permission to start may be received directly by the engine controller 30Cc through a one-to-one communication line or an in-vehicle network such as CAN. It may be input to the engine controller 30Cc from the host controller after being taken into the controller.

Then, in step S110, the inverter 18Ac starts servo control of the motor generator. As a result, the inverter 18Ac performs sensorless control of the motor-generator while estimating the rotation angle of the motor-generator based on the detected initial rotation angle when the engine is started in step S112, which will be described later, thereby assisting the rotation of the engine. and the rpm can be increased.

On the other hand, in step S112, the engine controller 30Cc drives the starter to start the engine in response to the reception of the start permission notification.

Then, the engine controller 30Cc increases the rotation speed of the engine after the completion of starting the engine, and in step S114, the rotation speed of the engine reaches a predetermined operating rotation speed (for example, 1000 rpm (round per minute)). In response to this, a notification of reaching the operating rotation speed is transmitted to the HMI 50c. At this time, the driving rotation speed arrival notification may be directly transmitted to the HMI 50c through a one-to-one communication line or an in-vehicle network such as CAN. It may be input to HMI 50c. The same applies to the case of step S212 in FIG. 4 below.

In step S116, the HMI 50c notifies the operator of the cabin of the operation permission by visual display, voice, or the like, for example.

In step S118, the operator receives the operation permission notice from the HMI 50c and starts operating the excavator according to the comparative example.

As described above, in the excavator according to the comparative example, the process of detecting the initial rotation angle of the motor-generator is performed before the engine is started, so the start of the engine is relatively delayed. As a result, there is a possibility that the time required from the start of the excavator until the operator can actually operate the excavator is relatively long.

<Method for controlling motor generator according to the present embodiment>
Next, a method of controlling the motor generator 12 by the inverter 18A of the excavator according to the present embodiment will be described with reference to FIGS. 4A to 4C.

4A to 4C are diagrams for explaining the operation of the shovel according to the present embodiment when it is started. Specifically, FIG. 4A is a sequence diagram showing the operation of the shovel according to this embodiment when it is started. FIG. 4B is a flowchart schematically showing an example of alignment trial processing by the inverter 18A (control circuit). FIG. 4C is a diagram (graphs 410 to 440) showing temporal changes in various states corresponding to the operation of the shovel according to the present embodiment when it is started. More specifically, in FIG. 4C, the graphs 410 to 440 indicate whether the excavator is in a starting state or a stopped state, whether the servo of the motor generator 12 is ON or servo OFF, and the rotation angle of the rotating shaft of the motor generator 12 ( solid line), and each time change of the electric current value of the motor generator 12 is shown. Further, in FIG. 4C, the dotted line of graph 410 indicates the temporal change of the rotation angle of motor generator 12 estimated by inverter 18A (hereinafter, "estimated rotation angle").

As shown in FIG. 4A, steps S202 and S204 are the same as steps S102 and S104 in FIG. 3, so description thereof will be omitted.

In step S206, the engine controller 30C drives the starter motor 11st to start the engine 11 as power supply is started by turning on the key switch.

On the other hand, the inverter 18A sets the initial value of the rotation angle, which is the reference for estimating the absolute rotation angle in the sensorless control, in parallel with the start of the engine 11 when the power supply is started when the key switch is turned ON. A control for matching the actual rotation angle of the motor generator 12 (hereinafter referred to as "alignment trial control") is performed. In the trial alignment control, the servo control of the motor generator 12 is trial-started (that is, the servo is turned ON) and then stopped (that is, the servo is turned OFF), which is repeated.

Specifically, as shown in FIG. 4B, in step S302, the inverter 18A provisionally sets the initial position (initial value) of the rotating shaft of the motor generator 12 to a predetermined value (hereinafter referred to as "provisional value") θp. and proceed to step S304.

In step S304, the inverter 18A turns on the servo of the motor generator 12 and starts servo control on a trial basis. Specifically, the inverter 18A performs servo control of the motor generator 12 based on the estimated rotation angle while estimating the rotation angle of the rotation shaft of the motor generator 12 based on the provisional value θp as the initial value. .

In step S306, the inverter 18A determines whether or not the current detection value of the motor generator 12 (that is, the detection value of the current sensor 12s1) has exceeded a predetermined threshold ith. This is because in an overcurrent state in which the detected current value of the motor generator 12 is relatively high, there is a high possibility that the initial value of the rotation angle deviates greatly from the actual initial rotation angle, and the servo control cannot be continued appropriately. . If the current detection value of the motor generator 12 does not exceed the threshold ith, the inverter 18A proceeds to step S308, and if it exceeds the threshold ith, the inverter 18A proceeds to step S310.

In step S306, instead of determining whether or not the current detection value of the motor generator 12 exceeds the threshold ith, the estimated rotation angle based on the provisional value θp converges to zero (within a predetermined time). It may be determined whether

In step S308, the inverter 18A determines whether or not a predetermined period of time or more has elapsed since the start of the trial servo control, that is, whether or not a stable state below the threshold value ith has continued for a predetermined period of time or longer since the start of the servo control. judge. If the predetermined time has not yet passed since the start of the trial servo control, the inverter 18A returns to step S306 and repeats the processing of steps S306 and S308. , and terminates the current process.

On the other hand, in step S310, the inverter 18A once stops the servo control, that is, turns off the servo of the motor generator 12, and proceeds to step S312.

In step S312, the inverter 18A determines whether or not a predetermined time has passed since the servo was turned off. If the predetermined time has not elapsed since the servo was turned off, the inverter 18A waits until the predetermined time elapses (that is, repeats the processing of this step), and if the predetermined time elapses, the processing after step S302 is performed again. repeat.

For example, as shown in FIG. 4C, at time t1, as shown in a graph 410, when the shovel is started (steps S202 and S204 in FIG. 4A), the engine 11 is started (step S206 in FIG. 4A), and the graph As indicated by 430, as the engine 11 starts rotating, the rotation speed of the electric motor generator 12 starts to increase.

In parallel with this, at time t1, trial servo control of the motor generator 12 is started as shown in the graph 420, that is, the servo of the motor generator 12 is turned ON, and motor power generation is performed based on the provisional value θp. Servo control of the motor generator 12 is performed while the rotation angle of the motor 12 is estimated (steps S302 and S304 in FIG. 4B). At this time, as shown in graph 430, the difference between the provisional value θp and the actual rotation angle of the motor-generator 12 near time t1 is relatively large. Therefore, as shown in graphs 430 and 440, the current detection value of the motor generator 12 exceeds the threshold ith at time t2 before the estimated rotation angle converges to the actual rotation angle. Therefore, at time t2, the servo of the motor generator 12 is temporarily turned OFF, and the trial servo control of the motor generator 12 is once terminated (YES in step S306 of FIG. 4B, step S310).

After a predetermined time has elapsed since the servo was turned off (step S312 in FIG. 4B), the servo of the motor generator 12 is turned on again at time t3, and the rotation angle of the motor generator 12 is estimated based on the provisional value θp. Servo control of the motor generator 12 is performed (steps S302 and S304 in FIG. 4B (second time)). At this time, as shown in a graph 430, between time t1 and time t3, the rotation speed of the engine 11 increases, and accordingly the rotation speed of the motor generator 12 also increases. The difference from the actual rotation angle of the machine 12 is relatively small. Therefore, as shown in graphs 430 and 440, the estimated rotation angle converges to the actual rotation angle before the current detection value of the motor generator 12 exceeds the threshold ith, and after time t3, the current detection value of the motor generator 12 The value is suppressed below the threshold ith (YES in step S308 of FIG. 4B). That is, in this example, the positioning is successful by the second trial servo control, and the trial servo control is shifted to the continuous servo control.

Returning to FIG. 4A , if the alignment associated with the alignment trial control is successful, the inverter 18A directly starts the servo control of the motor generator 12 in step S210, that is, the trial servo of the motor generator 12. Go from control to continuous servo control. As a result, the inverter 18A performs sensorless control of the motor-generator 12 while estimating the rotation angle of the motor-generator 12 based on the aligned initial value (provisional value θp), assists the rotation of the engine 11, and rotates the motor-generator 12. number can be increased.

On the other hand, the engine controller 30C increases the rotation speed of the engine 11 after the start of the engine 11 is completed, and in step S212, according to the rotation speed of the engine 11 reaching a predetermined operation rotation speed, the operation rotation speed is increased. A number arrival notice is sent to the HMI 50 .

Steps S214 and S216 are the same as steps S116 and S118 in FIG. 3, so description thereof will be omitted.

In this way, since the motor-generator 12 is rotated with the rotation of the engine 11, an arbitrary initial value (temporary The value θp) and the actual rotation angle of the motor-generator 12 become relatively closer. Therefore, the inverter 18A can appropriately start servo control based on the trial alignment control without detecting the initial state (initial rotation angle) of the motor generator 12 as in the comparative example described above. can. Therefore, it is possible to relatively shorten the time required from the start-up of the excavator until the operator can actually operate the excavator, thereby improving the work efficiency of the excavator.

In addition, instead of when the engine 11 is started, or in addition to the start of the engine 11, the alignment trial control is performed while the motor generator 12 is being rotated as the main pump 14 is rotated by the engine 11. It may be applied to other timings that need to be turned ON. For example, in the alignment trial control, after an abnormality related to the motor generator 12 is detected and the motor generator 12 (inverter 18A) is stopped, the timing at which the motor generator 12 (inverter 18A) recovers from the abnormality by restarting, etc. may be applied in This is because the engine 11 does not necessarily have to be stopped in the case of an abnormality related to the motor generator 12, and the servo control needs to be started while the motor generator 12 is being rotated as the engine 11 rotates.

[Action of this embodiment]
Next, the action of the excavator according to this embodiment will be described.

The excavator according to this embodiment includes a hydraulic actuator, a main pump 14 that supplies hydraulic fluid to the hydraulic actuator, a motor generator 12 that drives the main pump 14 , and an engine 11 that drives the main pump 14 . The excavator according to the present embodiment intermittently energizes the motor generator 12 while the motor generator 12 is being rotated with the rotation of the engine 11 .

Specifically, the excavator according to the present embodiment includes an inverter 18A (control circuit) that estimates the rotation angle of the motor generator 12 and controls the motor generator 12 based on the estimated rotation angle. The inverter 18A energizes the motor-generator 12 while the motor-generator 12 is being rotated by the rotation of the main pump 14 by the engine 11, and controls the motor-generator 12 while estimating the rotation angle. Repeat the action intermittently.

As a result, the inverter 18A turns on the servo of the motor-generator 12 without grasping the initial state of the motor-generator 12, and estimates the rotation angle based on, for example, a predetermined value (temporary value θp) as a reference (initial state). When the servo control cannot be appropriately continued, a series of operations of turning off the servo can be repeated. While this series of operations is repeated, the rotation angle of the motor-generator 12 changes as the engine 11 rotates, and the difference between the predetermined value (provisional value θp) and the actual rotation angle of the motor-generator 12 becomes becomes smaller, and the inverter 18A is able to continue servo control appropriately. Therefore, the inverter 18A can finally transition to continuous servo control without grasping the initial state of the motor generator 12 . Therefore, by shortening the time required for the operator to start work, work efficiency can be improved when sensorless control of the motor generator 12 is applied.

Further, in the present embodiment, the inverter 18A (control circuit) operates until the estimation error of the rotation angle of the motor-generator 12 converges, or until the current value of the motor-generator 12 is suppressed below a predetermined threshold. A series of actions are repeated intermittently.

As a result, the inverter 18A grasps whether the estimation error of the rotation angle of the motor generator 12 converges, or whether the current detection value of the motor generator 12 is suppressed to a predetermined threshold value (threshold value ith) or less. It can be determined that servo control can be continued. Therefore, the inverter 18A determines whether or not to continue the servo control of the motor generator 12 while repeating the above-described series of operations without grasping the initial state of the motor generator 12, and appropriately continues the servo control. can move to

More specifically, the inverter 18A energizes the motor-generator 12 while the motor-generator 12 is being rotated by the rotation of the main pump 14 by the engine 11, and the initial value (for example, , provisional value θp), the operation of controlling the motor generator 12 while estimating the rotation angle of the motor generator 12 is intermittently repeated.

As a result, the inverter 18A specifically repeats the above-described series of operations based on the initial value that does not depend on the measurement result, and finally shifts to continuous servo control.

Further, the excavator (inverter 18A) according to the present embodiment intermittently energizes the electric motor-generator 12 when the main pump 14 is started by the engine 11 as the excavator itself is started.

As a result, the inverter 18A can start servo control of the motor generator 12 without grasping the initial state of the motor generator 12 when the main pump 14 is started when the inverter 18A is started. Therefore, when the main pump 14 is started when the excavator is started, the time required for the operator to start work can be shortened, and the work efficiency of the excavator can be improved.

In addition, in the excavator (inverter 18A) according to the present embodiment, after an abnormality related to the motor generator 12 has occurred, the motor generator 12 is rotated as the main pump 14 is rotated by the engine 11 when recovering from the abnormality. In this state, the motor generator 12 is intermittently energized.

As a result, the inverter 18A is temporarily stopped due to the occurrence of an abnormality related to the motor generator 12, and when recovering from the abnormality such as by restarting, servo control of the motor generator 12 is performed without grasping the initial state of the motor generator 12. can be started. Therefore, when the motor generator 12 temporarily stopped due to the abnormality related to the motor generator 12 recovers from the abnormality, the required time until the operator can start the work can be shortened, and the work efficiency of the shovel can be improved.

[Transformation/change]
Although the embodiments for carrying out the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various can be transformed or changed.

For example, in the above-described embodiments, any working machine (industrial vehicle, forklift, crane, etc.) having an engine and a motor-generator as a power source of the hydraulic drive system may be applied instead of the excavator.

In addition, in the above-described embodiments and modifications, a work machine such as a shovel may be remotely operated from outside the work machine instead of being operated by an operator inside the cabin 10 . For example, the work machine has a communication device capable of communicating with a predetermined external device, receives an operation signal related to remote operation from the external device through the communication device, and responds to the operation signal by controlling the control valve 17 and the inverters 18A and 18B. may be controlled.

Further, in the above-described embodiments and modifications, the work machine such as the excavator autonomously performs a predetermined work without depending on the operation by the operator in the cabin 10 or the remote operation based on the operation signal from the external device. good too.

Moreover, in the above-described embodiment and modification, the main pump 14 may be driven only by the power of the motor generator 12 except when it is started. That is, in the above-described embodiments and modifications, the working machine such as the excavator may be an electric working machine that does not have the engine 11 and is driven only by the electric power of the power storage system 120, or the engine 11 is used for power generation. It may be a series type hybrid work machine that is utilized. In this case, the main pump 14 and the pilot pump 15 are normally driven only by the power of the motor-generator 12 . In addition, when the main pump 14 and the pilot pump 15 are started, the main pump 14 and the pilot pump 15 are mainly used as starting means corresponding to the starter motor 11st. ) to a certain number of revolutions (for example, 200 to 300 rpm), and then driven only by the power of the motor generator 12 . Therefore, when the main pump 14 is started by the other electric motor, the inverter 18A rotates the motor-generator 12 with the rotation of the other electric motor (specifically, the rotation of the main pump 14 by the other electric motor). In this state, the motor generator 12 may be intermittently energized. As a result, the same actions and effects as those of the above-described embodiment and modifications are achieved.

1A, 1B travel hydraulic motor (hydraulic actuator)
7 boom cylinder (hydraulic actuator)
8 arm cylinder (hydraulic actuator)
9 bucket cylinder (hydraulic actuator)
11 engine (other driving means)
11st starter motor 12 motor generator (motor)
14 Main pump (hydraulic pump)
18A inverter (control device)
30 control device 30A excavator controller 30B hybrid controller (control device)
30C engine controller

Claims (6)

a hydraulic actuator;
a hydraulic pump that supplies hydraulic fluid to the hydraulic actuator;
an electric motor that drives the hydraulic pump;
another driving means for driving the hydraulic pump;
a control device that estimates a rotation angle of the electric motor and controls the electric motor based on the estimated rotation angle;
Until the error between the estimated value and the actual value of the rotation angle converges, or until the current value of the electric motor is suppressed below a predetermined threshold, the rotation of the hydraulic pump by the other drive means intermittently energizing the electric motor while the electric motor is being rotated accordingly;
working machine. The control device controls the electric motor while estimating the rotation angle by energizing the electric motor while the electric motor is being rotated by the rotation of the hydraulic pump by the other driving means. repeat intermittently,
A work machine according to claim 1. The control device energizes the electric motor in a state in which the electric motor is rotated by the rotation of the hydraulic pump by the other driving means, and determines the rotation angle based on an initial value that does not depend on the measurement results. intermittently repeating the operation of controlling the electric motor while estimating;
A work machine according to claim 2 . intermittently energizing the electric motor when the hydraulic pump is started by the other driving means accompanying the start of the own machine;
A working machine according to any one of claims 1 to 3 . After an abnormality related to the electric motor occurs, when recovering from the abnormality , the electric motor is intermittently energized while the electric motor is being rotated as the hydraulic pump is rotated by the other driving means;
A working machine according to any one of claims 1 to 4 . the other driving means is an engine,
The electric motor assists the engine to drive the hydraulic pump,
A work machine according to any one of claims 1 to 5 .

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