JP4745322B2 - Swivel drive control device and construction machine including the same - Google Patents

Description

  The present invention relates to a turning drive control device that performs drive control of a turning mechanism of a construction machine, and a construction machine including the same.

Conventionally, a construction machine having an electric motor as a power source of a turning mechanism for turning an upper turning body has been proposed. In such a construction machine, the turning mechanism is accelerated (driven) by the power running operation of the electric motor, the regenerative operation is performed when the turning mechanism is decelerated (braking), and the generated electric power is charged in the battery (for example, , See Patent Document 1). Further, the construction machine described in Patent Document 1 includes a hydraulic pump for hydraulically driving a drive mechanism other than the turning mechanism, and the engine for driving the hydraulic pump generates power via a speed increaser. The machine is connected and the electric power obtained by power generation is used for charging the battery and driving the electric motor of the turning mechanism.
Japanese Patent Laid-Open No. 2004-036303

  By the way, when accelerating the electric motor, if the rotational speed is low, a large driving torque is required to improve acceleration, but if the rotational speed increases to some extent, the driving torque is smaller than when the rotational speed is low. It ’s enough.

  Also, when the motor is decelerated, if the rotational speed is high, a large driving torque (driving torque in the direction opposite to the rotational direction) is required to improve the deceleration, but if the rotational speed decreases to some extent, A smaller driving torque is sufficient than when the rotational speed is high.

  However, in conventional construction machines, the driving torque during acceleration / deceleration is kept constant regardless of the rotational speed of the electric motor for turning, so that power consumption efficiency is improved when acceleration is performed with the rotational speed increased to some extent. There was a problem of a decrease. Further, when the rotational speed is reduced to some extent, the braking torque is large, so that there is a problem that it is difficult to stop smoothly and the riding comfort is lowered.

  In addition, even when the rotational speed is high, the same drive torque as when the rotational speed is low is supplied. Therefore, the motor and the inverter must have the rated specifications that can handle the high rotational speed and high torque conditions. As a result, the size of electric motors and inverters was increased.

  Then, an object of this invention is to provide the turning drive control apparatus which enables the improvement of power consumption efficiency, and size reduction of an electric motor and an inverter, and a construction machine including the same.

  A turning drive control device according to one aspect of the present invention is a turning drive control device that drives and controls a turning mechanism of a construction machine that is driven to turn by an electric motor, and is based on an operation amount that is input via an operation unit of the construction machine. A drive command generating means for generating a drive command for driving the electric motor, and a rotational speed detecting means for detecting the rotational speed of the electric motor, wherein the drive command generating means is detected by the rotational speed detecting means. Output limiting means for limiting the output of the electric motor according to the drive command according to the rotational speed of the motor, and when the motor is in a power running operation, the rotational speed is an absolute value that is equal to or higher than the first rotational speed lower than the maximum speed. The output of the motor is limited to a first ratio or less of the maximum output, and during the regenerative operation of the motor, the output of the motor is reduced when the rotation speed is equal to or less than a second rotation speed that is lower than the maximum speed in absolute value. Limited to not more than a second percentage of high output, and an output limiting means.

  Further, the output limiting means is configured to limit the output by limiting the driving torque of the electric motor, and during the power running operation of the electric motor, the rotation speed is an absolute value lower than the maximum speed. When the number of revolutions exceeds 1, the output is limited so that the driving torque of the electric motor is equal to or less than the first torque lower than the maximum torque in absolute value, and the revolving speed of the electric motor is the highest in absolute value during regenerative operation. The output may be limited so that the braking torque of the electric motor is less than the second torque lower than the maximum torque in absolute value when the second rotation speed is lower than the speed.

  Further, the output limiting means may limit the output of the electric motor to a constant when the rotational speed becomes an absolute value or more than the first rotational speed during the power running operation of the electric motor.

  A construction machine according to one aspect of the present invention includes the turning drive control device according to any one of the above.

  According to the present invention, by limiting the output of the electric motor, there is obtained a specific effect that it is possible to provide a turning drive control device and a construction machine including the same that can improve the power consumption efficiency and reduce the size of the electric motor and the inverter. It is done.

  Hereinafter, an embodiment to which a turning drive control device of the present invention and a construction machine including the same are applied will be described.

  FIG. 1 is a side view showing a construction machine including a turning drive control device of the present embodiment.

  An upper swing body 3 is mounted on the lower traveling body 1 of the construction machine via a swing mechanism 2. In addition to the boom 4, the arm 5, and the bucket 6, and the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 for hydraulically driving them, the upper swing body 3 is equipped with a cabin 10 and a power source. Is done.

"overall structure"
FIG. 2 is a block diagram showing the configuration of the construction machine including the turning drive control device of the present embodiment. In FIG. 2, the mechanical power system is indicated by a double line, the high-pressure hydraulic line is indicated by a solid line, the pilot line is indicated by a broken line, and the electric drive / control system is indicated by a one-dot chain line.

  An engine 11 as a mechanical drive unit and a motor generator 12 as an assist drive unit are both connected to an input shaft of a speed reducer 13 as a booster. A main pump 14 and a pilot pump 15 are connected to the output shaft of the speed reducer 13. A control valve 17 is connected to the main pump 14 via a high pressure hydraulic line 16.

  The control valve 17 is a control device that controls the hydraulic system in the construction machine of the present embodiment. The control valve 17 includes hydraulic motors 1A (for right) and 1B (for left) for the lower traveling body 1, The boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 are connected via a high pressure hydraulic line.

  In addition, a battery 19 is connected to the motor generator 12 via an inverter 18, and a turning motor 21 is connected to the battery 19 via an inverter 20.

  A resolver 22, a mechanical brake 23, and a turning speed reducer 24 are connected to the rotating shaft 21 a of the turning electric motor 21. An operation device 26 is connected to the pilot pump 15 through a pilot line 25.

  A control valve 17 and a pressure sensor 29 are connected to the operating device 26 via hydraulic lines 27 and 28, respectively. The pressure sensor 29 is connected to a controller 30 that performs drive control of the electric system of the construction machine according to the present embodiment.

  The construction machine of this embodiment is a hybrid construction machine that uses the engine 11, the motor generator 12, and the turning electric motor 21 as power sources. These power sources are mounted on the upper swing body 3 shown in FIG. Hereinafter, each part will be described.

"Configuration of each part"
The engine 11 is an internal combustion engine composed of, for example, a diesel engine, and its output shaft is connected to one input shaft of the speed reducer 13. The engine 11 is always operated during the operation of the construction machine.

  The motor generator 12 may be an electric motor capable of both power running operation and regenerative operation. Here, a motor generator that is AC driven by an inverter 18 is shown as the motor generator 12. The motor generator 12 can be constituted by, for example, an IPM (Interior Permanent Magnetic) motor in which a magnet is embedded in a rotor. The rotating shaft of the motor generator 12 is connected to the other input shaft of the speed reducer 13.

  The speed reducer 13 has two input shafts and one output shaft. A drive shaft of the engine 11 and a drive shaft of the motor generator 12 are connected to each of the two input shafts. Further, the drive shaft of the main pump 14 is connected to the output shaft. When the load on the engine 11 is large, the motor generator 12 performs a power running operation, and the driving force of the motor generator 12 is transmitted to the main pump 14 via the output shaft of the speed reducer 13. Thereby, driving of the engine 11 is assisted. On the other hand, when the load on the engine 11 is small, the driving force of the engine 11 is transmitted to the motor generator 12 via the speed reducer 13 so that the motor generator 12 generates power by regenerative operation. Switching between the power running operation and the regenerative operation of the motor generator 12 is performed by the controller 30 according to the load of the engine 11 and the like.

  The main pump 14 is a pump that generates hydraulic pressure to be supplied to the control valve 17. This hydraulic pressure is supplied to drive each of the hydraulic motors 1 </ b> A and 1 </ b> B, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 via the control valve 17.

  The pilot pump 15 is a pump that generates a pilot pressure necessary for the hydraulic operation system. The configuration of this hydraulic operation system will be described later.

  The control valve 17 inputs the hydraulic pressure supplied to each of the hydraulic motors 1A, 1B, the boom cylinder 7, the arm cylinder 8 and the bucket cylinder 9 for the lower traveling body 1 connected via a high-pressure hydraulic line. It is a hydraulic control device which controls these hydraulically by controlling according to the above.

  The inverter 18 supplies electric power necessary for the power running operation of the motor generator 12 from the battery 19 to the motor generator 12, and at the same time, charges the battery 19 with electric power generated by the regenerative operation of the motor generator 12. It is an inverter provided between the machine 12 and the battery 19.

  The battery 19 is disposed between the inverter 18 and the inverter 20. As a result, when at least one of the motor generator 12 and the turning electric motor 21 is performing the power running operation, the electric power necessary for the power running operation is supplied, and at least one of them is performing the regenerative operation. The power source for storing the regenerative power generated by the regenerative operation as electrical energy.

  The inverter 20 is provided between the turning electric motor 21 and the battery 19 as described above, and performs operation control on the turning electric motor 21 based on a command from the controller 30. As a result, when the inverter controls the power of the turning electric motor 21, the necessary electric power is supplied from the battery 19 to the turning electric motor 21. Further, when the turning electric motor 21 is performing a regenerative operation, the battery 19 is charged with the electric power generated by the turning electric motor 21.

  The turning electric motor 21 may be an electric motor capable of both power running operation and regenerative operation, and is provided for driving the turning mechanism 2 of the upper turning body 3. During the power running operation, the rotational force of the rotational driving force of the turning electric motor 21 is amplified by the speed reducer 24, and the upper turning body 3 is subjected to acceleration / deceleration control to perform rotational motion. Further, due to the inertial rotation of the upper swing body 3, the number of rotations is increased by the speed reducer 24 and transmitted to the turning electric motor 21, and regenerative power can be generated. Here, as the electric motor 21 for turning, an electric motor driven by an inverter 20 by a PWM (Pulse Width Modulation) control signal is shown. The turning electric motor 21 can be constituted by, for example, a magnet-embedded IPM motor. Thereby, since a larger induced electromotive force can be generated, the electric power generated by the turning electric motor 21 at the time of regeneration can be increased.

  The charge / discharge control of the battery 19 is based on the state of charge of the battery 19, the operation state of the motor generator 12 (powering operation or regenerative operation), and the operation state of the turning motor 21 (powering operation or regenerative operation). Is done by.

  The resolver 22 is a sensor that detects the rotational position and the rotational angle of the rotating shaft 21A of the turning electric motor 21, and is mechanically connected to the turning electric motor 21 to rotate the rotating shaft 21A before the turning electric motor 21 rotates. The rotation angle and the rotation direction of the rotation shaft 21A are detected by detecting the difference between the position and the rotation position after the left rotation or the right rotation. By detecting the rotation angle of the rotation shaft 21A of the turning electric motor 21, the rotation angle and the rotation direction of the turning mechanism 2 are derived.

  The mechanical brake 23 is a braking device that generates a mechanical braking force, and mechanically stops the rotating shaft 21 a of the turning electric motor 21. This mechanical brake 23 is switched between braking (on) and releasing (off) by an electromagnetic switch.

  The turning speed reducer 24 is a speed reducer that reduces the rotational speed of the rotating shaft 21 a of the turning electric motor 21 and mechanically transmits it to the turning mechanism 2.

  The turning mechanism 2 can turn in a state where the mechanical brake 23 of the turning electric motor 21 is released, and in this state, the upper turning body 3 is turned leftward or rightward.

  The operation device 26 is an operation device for operating the turning electric motor 21, the lower traveling body 1, the boom 4, the arm 5, and the bucket 6, and includes levers 26A and 26B and a pedal 26C. The lever 26 </ b> A is a lever for operating the turning electric motor 21 and the arm 5, and is provided in the vicinity of the driver seat of the upper turning body 3. The lever 26B is a lever for operating the boom 4 and the bucket 6, and is provided in the vicinity of the driver's seat. The pedals 26C are a pair of pedals for operating the lower traveling body 1, and are provided under the feet of the driver's seat.

  The operating device 26 converts the hydraulic pressure (primary hydraulic pressure) supplied through the pilot line 25 into hydraulic pressure (secondary hydraulic pressure) corresponding to the operation amount of the driver and outputs the converted hydraulic pressure. The secondary hydraulic pressure output from the operating device 26 is supplied to the control valve 17 through the hydraulic line 27 and detected by the pressure sensor 29.

  When each of the levers 26A and 26B and the pedal 26C is operated, the control valve 17 is driven through the hydraulic line 27, whereby the hydraulic pressure in the hydraulic motors 1A and 1B, the boom cylinder 7, the arm cylinder 8 and the bucket cylinder 9 is increased. Is controlled, the lower traveling body 1, the boom 4, the arm 5, and the bucket 6 are driven.

  The mechanical brake 23 is configured to be released by the controller 30 when any of the levers 26A and 26B or the pedal 26C is operated.

  The hydraulic line 27 supplies hydraulic pressure necessary for driving the hydraulic motors 1A and 1B, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder to the control valve.

  In the pressure sensor 29, a change in hydraulic pressure in the hydraulic line 28 due to the operation of the lever 26 </ b> A is detected by the pressure sensor 29. The pressure sensor 29 outputs an electrical signal indicating the hydraulic pressure in the hydraulic line 28. This electrical signal is input to the controller 30.

"Controller 30"
The controller 30 is a control device that performs drive control of the construction machine according to the present embodiment, and includes a speed command conversion unit 31, a drive control device 32, and a turning drive control device 40. The controller 30 includes a CPU (Central Processing Unit) and an arithmetic processing device including an internal memory. The speed command conversion unit 31, the drive control device 32, and the turning drive control device 40 include the CPU of the controller 30 in the internal memory. It is an apparatus realized by executing a stored drive control program.

  The speed command conversion unit 31 is an arithmetic processing unit that converts a signal input from the pressure sensor 29 into a speed command. Thereby, the operation amount of the lever 26A is converted into a speed command (rad / s) for rotating the turning electric motor 21. This speed command is input to the drive control device 32 and the turning drive control device 40.

  The drive control device 32 is a control device for performing operation control of the motor generator 12 (switching between power running operation or regenerative operation) and charge / discharge control of the battery 19. The drive control device 32 switches between the power running operation and the regenerative operation of the motor generator 12 according to the load state of the engine 11 and the charge state of the battery 19. The drive control device 32 performs charge / discharge control of the battery 19 via the inverter 18 by switching between the power running operation and the regenerative operation of the motor generator 12.

  Here, in the control system of the construction machine of the present embodiment, the rotation direction in which the rotating shaft 21a of the turning electric motor 21 rotates counterclockwise is referred to as “forward rotation”, and the control amount represents the drive in the forward rotation direction. Add a positive sign. On the other hand, the rotation direction in which the rotating shaft 21a of the turning electric motor 21 rotates clockwise is referred to as “reverse rotation”, and a negative sign is assigned to the control amount indicating the drive in the reverse rotation direction. Forward rotation corresponds to turning of the upper swing body 3 in the right direction, and reverse rotation corresponds to turning of the upper swing body in the left direction.

"Swivel drive control device 40"
FIG. 3 is a control block diagram showing the configuration of the turning drive control device 40 of the present embodiment.

  The turning drive control device 40 is a control device for performing drive control of the turning electric motor 21 via the inverter 20, and includes a drive command generating unit 50 that generates a drive command for driving the turning electric motor 21, and a main command. A control unit 60 is included.

  The drive command generator 50 receives a speed command output from the speed command converter 31 according to the amount of operation of the lever 26A, and the drive command generator 50 generates a drive command based on the speed command. The drive command output from the drive command generation unit 50 is input to the inverter 20, and the turning electric motor 21 is AC-driven by the inverter 20 using the PWM control signal.

  The main control unit 60 is a control unit that performs peripheral processing necessary for the control processing of the drive command generation unit 50. Specific processing contents will be described each time in related sections.

  The turning drive control device 40 controls the switching between the power running operation and the regenerative operation when driving the turning electric motor 21 according to the operation amount of the operation lever 26A, and also controls the battery 19 via the inverter 20. Charge / discharge control is performed.

"Drive command generation unit 50"
The drive command generator 50 includes a subtractor 51, a PI (Proportional Integral) controller 52, a torque limiter 53, a torque limiter 54, a subtractor 55, a PI controller 56, a current converter 57, and a turning motion detector 58. including. A speed command (rad / s) for turning drive corresponding to the operation amount of the lever 26A is input to the subtractor 51 of the drive command generation unit 50.

  The subtractor 51 subtracts the rotational speed (rad / s) of the turning electric motor 21 detected by the turning motion detector 58 from the value of the speed command (hereinafter referred to as speed command value) corresponding to the operation amount of the lever 26A. Output the deviation. This deviation is used in PI control for causing the rotational speed of the turning electric motor 21 to approach the speed command value (target value) in the PI control unit 52 described later.

  Based on the deviation input from the subtractor 51, the PI control unit 52 performs PI control so that the rotation speed of the turning electric motor 21 approaches the speed command value (target value) (that is, this deviation is reduced). And a torque current command necessary for that is calculated. The generated torque current command is input to the torque limiter 53.

  The torque limiter 53 performs a process of limiting the value of the torque current command (hereinafter, torque current command value) according to the operation amount of the lever 26A. This limiting process is performed based on a limiting characteristic in which the allowable value of the torque current command value gradually increases according to the operation amount of the lever 26A. Such limitation of the torque current command value is performed in order to suppress this because the controllability deteriorates when the torque current command value calculated by the PI control unit 52 increases rapidly.

  This limiting characteristic has a characteristic of gradually increasing the allowable value (absolute value) of the torque current command value as the amount of operation of the lever 26A increases. It has the characteristic for restricting. Data representing the limiting characteristic is stored in the internal memory of the main control unit 60, read by the CPU of the main control unit 60, and input to the torque limiting unit 53.

  The torque limiter 54 limits the torque current command value input from the torque limiter 53 so that the torque generated by the torque current command input from the torque limiter 53 is less than or equal to the maximum allowable torque value of the turning electric motor 21. To do. The torque current command value is limited with respect to the bi-directional rotation of the upper swing body 3 in the left direction and the right direction, similarly to the torque limiting unit 53.

  The upper limit value (maximum value for right turn) and the lower limit value (minimum value for left turn) for limiting the torque current command value in the torque limit unit 54 are set by the torque limit unit 54. Even if this limitation is performed, the value is set such that the construction machine can generate a sufficient driving torque to perform the work.

  The subtractor 55 outputs a deviation obtained by subtracting the output value of the current converter 57 from the torque current command value input from the torque limiter 54. This deviation is the torque current that is input via the torque limiter 54 to the drive torque of the turning electric motor 21 that is output from the current converter 57 in a feedback loop that includes a PI controller 56 and a current converter 57 described later. It is used for PI control to approach the torque represented by the command value (target value).

  Based on the deviation input from the subtractor 55, the PI control unit 56 performs PI control so as to reduce this deviation, and generates a torque current command as a final drive command to be sent to the inverter 20. The inverter 20 PWM drives the turning electric motor 21 based on the torque current command input from the PI control unit 56.

  The current converter 57 detects the motor current of the turning electric motor 21, converts it into a value corresponding to the torque current command, and inputs it to the subtractor 55.

  The turning motion detector 58 detects a change in the rotational position of the turning electric motor 21 detected by the resolver 22 (that is, turning of the upper turning body 3), and the rotation of the turning electric motor 21 from the temporal change in the rotational position. The speed is derived by differential operation. Data representing the derived rotational speed is input to the subtractor 51 and the main control unit 60.

  In the drive command generation unit 50 having such a configuration, a torque current command for driving the turning electric motor 21 is generated based on the speed command input from the speed command conversion unit 31, and the upper swing body 3 is moved to a desired position. It is turned to.

  In the turning drive control device of the present embodiment and the construction machine using the same, the allowable value of the torque current command calculated by the main control unit 60 described in detail below is transmitted to the torque limiting unit 53, and the torque current command Is limited.

  FIG. 4 is a diagram illustrating a torque limiting characteristic used in the torque limiting unit 54 of the turning drive control device of the present embodiment. This torque limiting characteristic is a characteristic used by the main control unit 60 to calculate an allowable value of a torque current command for limiting the drive torque in accordance with the rotational speed of the turning electric motor 21. Data representing the torque limiting characteristic is stored in the internal memory of the main control unit 60. The main control unit 60 calculates the allowable value of the torque current command based on the rotation speed using the torque limiting characteristic shown in FIG. 4 and inputs this to the torque limiting unit 54, thereby performing power running operation and regenerative operation. At this time, the output of the turning electric motor 21 is limited to an allowable value or less.

  Note that the turning electric motor 21 generates braking torque by generating power during regenerative operation, and the energy balance is opposite to that during power running that generates drive torque. However, in this embodiment, during regenerative operation The integral value of the rotation speed and braking torque is treated as an output. The declaration of the output during the regenerative operation is performed by limiting the output to an absolute value below a predetermined degree of the maximum output of the turning electric motor 21.

  As shown in FIG. 4, the torque limiting characteristic is represented by coordinates with the rotation speed (rad / s) as the horizontal axis and the torque (Nm) as the vertical axis. In this coordinate, the horizontal axis is positive on the right side from the origin and negative on the left side, and the vertical axis is positive on the upper side from the origin and negative on the lower side. The positive value on the horizontal axis represents the rotational speed (rad / s) in the forward direction, and the negative value represents the rotational speed in the reverse direction. A positive value on the vertical axis represents drive torque (Nm) in the forward direction, and a negative value represents drive torque (Nm) in the reverse direction.

  In the torque limiting characteristic having such a coordinate system, a region A in the first quadrant represents acceleration (powering) operation during a right turn (forward rotation), and a region B in the second quadrant represents a left turn (reverse rotation). ) Represents deceleration (regeneration) operation. A region C in the third quadrant represents acceleration (power running) operation during left turn (reverse rotation), and a region D in the fourth quadrant represents deceleration (regeneration) operation during right turn (forward rotation).

  Here, the rotational speed ω1 represents the maximum rotational speed in the forward rotation direction of the turning electric motor 21, and is ω2 = 0.6 · ω1 and ω3 = 0.4 · ω1. The same applies to the relationship of “−ω1”, “−ω2”, and “−ω3” in the reverse direction.

  The torque T1 represents the maximum torque in the forward rotation direction of the turning electric motor 21, and T2 = 0.6 · T1. The same applies to the relationship between “−T1” and “−T2” in the reverse direction.

  In FIG. 4, the vertical axis indicates the torque (Nm), but the main control unit 60 converts the torque (Nm) limited by the torque limiting characteristic of FIG. Input to the unit 54.

  In the first quadrant, the region A has a rotational speed of ω1 or less and a torque of T1 or less, and is closer to the origin than the constant output curve a connecting the points (ω2, T1) and (ω1, T2). It is an existing area. As described above, since ω2 = 0.6 · ω1 and T2 = 0.6 · T1, the constant output curve a indicates that the turning electric motor 21 performs the power running operation in the forward rotation direction (right turning acceleration operation). This is a characteristic for limiting the output in the high rotational speed region to 60% or less of the maximum output. The region where the torque is higher than that of the constant output curve a is excluded. When the rotational speed is increased to some extent in the case of acceleration to the right turn, a larger torque is not required as the rotational speed is lower. This is because the power consumption of the turning electric motor 21 is reduced by limiting the size of.

  In the region B, in the second quadrant, the rotational speed is −ω1 or more and the torque is T1 or less, and the torque value is greater than the curve b connecting the point (−ω3, T1) and the point (0, T2). This is an area excluding an area where the As described above, −ω3 = 0.4 · (−ω1), and this curve b indicates the low rotation speed region (rotation) when the turning electric motor 21 performs the regenerative operation in the reverse direction (left turning deceleration operation). This is a characteristic for limiting the output in a region where the absolute value of the speed is small. The area where the torque is higher than the curve b is excluded. When the vehicle decelerates when turning counterclockwise, if the rotation speed in the reverse rotation direction decreases to some extent, the higher the rotation speed in the reverse rotation direction, the greater the torque required. Therefore, by limiting the magnitude of the braking torque, it is possible to make a smooth stop and improve the riding comfort.

  Region C is a constant output curve connecting the point (−ω2, −T1) and the point (−ω1, −T2) in the third quadrant where the rotational speed is −ω1 or more and the torque is −T1 or more. This is an area existing on the origin side from c. Similar to the constant output curve a, the constant output curve c is in a high rotation speed region (region where the absolute value of the rotation speed is large) when the turning electric motor 21 performs a power running operation in the reverse direction (left turning acceleration operation). The output is limited to 60% or less of the maximum output. The region where the torque is larger in the reverse rotation direction than the constant output curve c is excluded from the case where the rotation speed in the reverse rotation direction increases to some extent when the left turn acceleration is performed. This is because a large torque is not required, and thus the power consumption of the turning electric motor 21 is reduced by limiting the magnitude of the torque.

  In the region D, in the fourth quadrant, the rotational speed is ω1 or less, the torque is −T1 or more, and the torque is higher than the curve d connecting the point (ω3, −T1) and the point (0, −T2). This is an area excluding an area having a low value. As described above, ω3 = 0.4 · ω1, and this curve d limits the output in the low rotational speed region when the turning electric motor 21 performs the regenerative operation in the normal rotation direction (right turn deceleration operation). It is a characteristic to do. The region where the torque in the reverse rotation direction is larger than the curve d is excluded because when the vehicle is decelerating during a right turn, when the rotational speed decreases to some extent, the higher the rotational speed, the less torque is required. This is because by restricting the magnitude of the braking torque, a smooth stop can be achieved and the riding comfort can be improved.

  By the way, in the conventional construction machine, since the driving torque at the time of acceleration / deceleration is made constant irrespective of the rotational speed of the motor generator for turning, the characteristics corresponding to FIG. 4 are the constant output curves a and c and the curve b. And d do not exist, the rotation speed is -ω1 to ω1, and the torque is a region represented by a quadrangle determined by -T1 to T1. For this reason, high torque is output even in the high rotational speed region (region where the absolute value of the rotational speed is large) when performing power running operation, and low rotational speed region (the absolute value of the rotational speed is small when performing regeneration operation) High torque was output even in a small area.

  On the other hand, by restricting the torque current command using the torque limiting characteristic shown in FIG. 4 in the turning drive control device of the present embodiment, the power consumption can be reduced as follows.

"Swivel motion"
When the drive command is generated by the drive command generation unit 50 and the turning electric motor 21 is driven and the rotation speed detected by the turning operation detection unit 58 is input to the main control unit 60, the main control unit 60 Using the torque limiting characteristics shown in FIG. 2, an allowable value of the torque current command corresponding to the rotation speed is calculated and input to the torque limiting unit 54.

  When the torque current command value input from the PI control unit 52 is higher than the allowable value, the torque limiting unit 54 limits the torque current command value input from the PI control unit 52 to the allowable value, and the torque limiting unit 54 To enter. The limited torque current command value is input to the torque limiting unit 54. Thereby, the limitation of the drive torque of the electric motor 21 for turning according to the rotation speed is realized.

  On the other hand, when the torque current command value input from the PI control unit 52 is equal to or less than the allowable value, the torque limiting unit 54 inputs the torque current command value input from the PI control unit 52 to the torque limiting unit 54 as it is. .

  When the torque current command value input from the torque limiting unit 54 exceeds the torque current command value representing the maximum allowable torque of the turning electric motor 21, the torque limiting unit 54 receives the torque current input from the torque limiting unit 54. The command value is limited to a torque current command value representing the maximum allowable torque of the turning electric motor 21, and the limited torque current command value is input to the subtractor 55. When the torque current command value input from the torque limiting unit 54 does not exceed the torque current command value representing the maximum allowable torque of the turning electric motor 21, the torque limiting unit 54 is input from the torque limiting unit 54. The torque current command value is input to the subtractor 55 as it is.

  In the subtractor 55, the difference between the torque current command value input from the torque limiter 54 and the torque current command value input from the current converter is calculated. The calculated deviation is input to the PI control unit 56. In this PI control unit 56, PI control is performed with the torque current command value output from the torque limiting unit 54 as a target value, and this deviation is reduced. The torque current command value is calculated as the final drive command. With this final drive command, the turning electric motor 21 is driven and controlled via the inverter 20.

  Thus, in the construction machine using the turning drive control device of the present embodiment, torque is calculated using the torque limiting characteristic shown in FIG. 4 in the process of calculating the torque current command value for driving the turning electric motor 21. Limit the current command value. For this reason, power consumption is reduced as follows.

  When performing power running operation in the forward direction (right turning acceleration operation), if the output given by the integral value of the rotational speed and torque exceeds 60% of the maximum output, torque according to the rotational speed at that time The allowable value of the current command is calculated by the main control unit 60 using the constant output curve a, and the torque current command value is limited. Thereby, drive control is performed so that the output of the turning electric motor 21 is 60% or less of the maximum output, and power consumption can be reduced as compared with the conventional construction machine.

  Similarly, if the output given by the integral value of the rotational speed and torque exceeds 60% of the maximum output when performing a power running operation in the reverse direction (left-turn acceleration operation), it corresponds to the rotational speed at that time. The allowable value of the torque current command is calculated by the main control unit 60 using the constant output curve c, and the torque current command value is limited. Thereby, drive control is performed so that the output of the turning electric motor 21 is 60% or less of the maximum output, and power consumption can be reduced as compared with the conventional construction machine.

  In addition, when performing a regenerative operation in the reverse direction (left turn deceleration operation), if the rotational speed in the reverse direction becomes −ω3 or more (when the absolute value of the rotational speed is in a low rotational speed region of ω3 or less), The allowable value of the torque current command according to the rotational speed is calculated by the main control unit 60 using the curve b, and the torque current command value is limited. As a result, the vehicle can be stopped smoothly during deceleration to the left and the riding comfort is also improved.

  Similarly, when performing a regenerative operation in the normal rotation direction (right turn deceleration operation), if the rotation speed in the normal rotation direction is in a low rotation speed region of ω3 or less, the torque current corresponding to the rotation speed at that time The allowable value of the command is calculated by the main control unit 60 using the curve d, and the torque current command value is limited. Thereby, the power consumption at the time of right turn deceleration can be reduced rather than the conventional construction machine.

  Further, in the construction machine using the turning drive control device of the present embodiment, the power consumption can be reduced as described above, so the capacity of the turning electric motor 21 and the inverter 20 is smaller than that of the conventional construction machine. Can be Thereby, a construction machine can be provided at lower cost than before.

  In the above, the constant output curves a and c are used to limit the torque current command value in a region where the absolute value of the rotational speed in the forward rotation direction and the reverse rotation direction is large. As long as the command value can be limited, characteristics other than the constant output curve may be used.

  In addition, the curves b and d are used to limit the torque current command value in the region where the absolute value of the rotational speed in the forward rotation direction and the reverse rotation direction is small. As long as it can be limited, characteristics other than the curves b and d may be used.

  In the above description, the turning motor 21 is an AC motor that is PWM-driven by the inverter 20, and the form in which the resolver 22 and the turning motion detection unit 58 are used to detect the rotation speed has been described. A DC motor may be used. In this case, the inverter 20, the resolver 22, and the turning motion detection unit 58 are not necessary, and the value detected by the tachometer generator of the DC motor may be used as the rotation speed.

  In the above description, the PI control is used for calculating the torque current command. However, instead of this, robust control, adaptive control, proportional control, integral control, or the like may be used.

  In the above description, the hybrid construction machine is used. However, if the turning mechanism is an electric construction machine, the application target of the turning drive device according to the present embodiment is limited to the hybrid type. It is not something.

  As mentioned above, although the turning drive control apparatus of the exemplary embodiment of the present invention and the construction machine using the same have been described, the present invention is not limited to the specifically disclosed embodiment, Various modifications and changes can be made without departing from the scope of the claims.

It is a side view which shows the construction machine containing the turning drive control apparatus of this Embodiment. It is a block diagram showing the structure of the construction machine containing the turning drive control apparatus of this Embodiment. It is a control block diagram showing the structure of the turning drive control apparatus of this Embodiment. It is a figure which shows the torque limitation characteristic used with the torque limitation part 53 of the turning drive control apparatus of this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower traveling body 1A, 1B Traveling mechanism 2 Turning mechanism 3 Upper turning body 4 Boom 5 Arm 6 Bucket 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 10 Cabin 11 Engine 12 Motor generator 13 Reducer 14 Main pump 15 Pilot pump 16 High pressure Hydraulic line 17 Control valve 18 Inverter 19 Battery 20 Inverter 21 Electric motor for turning 23 Mechanical brake 24 Turning speed reducer 25 Pilot line 26 Operating device 26A, 26B Lever 26C Pedal 27 Hydraulic line 28 Hydraulic line 29 Pressure sensor 30 Controller 31 Speed command converter 32 Drive control device 40 Turning drive control device 50 Drive command generation unit 51 Subtractor 52 PI control unit 53 Torque limiter 54 Torque limiter 55 Subtractor 56 P Control unit 57 current conversion part 58 turning motion detection part 60 main control unit

Claims (6)

A turning drive control device that drives and controls a turning mechanism of a construction machine that is turned by an electric motor,
Drive command generation means for generating a drive command for driving the electric motor based on an operation amount input via an operation means of the construction machine;
Rotation speed detection means for detecting the rotation speed of the electric motor,
The drive command generating means is output limiting means for limiting the output of the electric motor according to the drive command in accordance with the rotational speed detected by the rotational speed detecting means, and the rotational speed is during power running operation of the electric motor. An output limiting means for limiting the output of the electric motor to a first ratio of the maximum output or less when the absolute value is greater than or equal to the first rotational speed lower than the maximum speed, and a current converter for converting the motor current into a torque current command value and, the possess,
The drive command generating means generates a drive command according to a deviation between the torque current command value limited by the output limiting means and the torque current command value converted by the current conversion unit;
Rotation drive control device. The output limiting means limits the output of the electric motor to a second ratio of the maximum output or less when the rotational speed is equal to or less than a second rotation speed that is lower than the maximum speed in the regenerative operation of the motor.
The turning drive device according to claim 1. The output limiting means is configured to limit the output by limiting the driving torque of the electric motor,
During the power running operation of the electric motor, when the rotational speed becomes equal to or higher than the first rotational speed lower than the maximum speed in absolute value, the driving torque of the electric motor becomes lower than the first torque lower than the maximum torque in absolute value. The output is limited, and during the regenerative operation of the electric motor, if the rotational speed is equal to or lower than the second rotational speed that is lower than the maximum speed in absolute value, the braking torque of the electric motor is the second torque that is lower than the maximum torque in absolute value. The turning drive control device according to claim 1 or 2, wherein the output is limited to be as follows. The second torque is greater than zero;
The turning drive control means according to claim 3. The allowable value of the torque current command value generated according to the deviation between the speed command value based on the operation amount and the rotation speed detected by the rotation speed detecting means is changed according to the change in the operation amount. A torque limiting means;
The turning drive control device according to any one of claims 1 to 4. A construction machine including the turning drive control device according to any one of claims 1 to 5 .

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