WO2009157485A1 - Hybrid working machine - Google Patents

Abstract

A hybrid working machine comprises a plurality of inverters for driving a plurality of electric work elements, an energy storage device for transferring power to from the plurality of inverters, a DC bus connected with the plurality of inverters, and a step-up/down converter arranged between the DC bus and the energy storage device.  The plurality of inverters include a first inverter and a second inverter.  The DC bus includes a first DC bus to which the first inverter is connected, and a second DC bus to which the second inverter is connected.  The step-up/down converter is arranged between the first DC bus and the energy storage device.

Description

Hybrid work machine

The present invention relates to a hybrid work machine in which a DC bus is provided in a power storage unit for supplying power.

Conventionally, a hybrid work machine in which a part of the drive mechanism is motorized has been proposed. There is a hybrid excavator as an example of such a hybrid work machine. The hybrid power shovel includes a hydraulic pump for hydraulically driving work elements such as a boom, an arm, and a bucket. A motor generator is connected to the engine for driving the hydraulic pump via a speed increaser, and the motor generator assists the driving of the engine and charges the battery with electric power obtained by power generation.

In addition to the hydraulic motor as a power source of the turning mechanism for turning the upper turning body, it is equipped with an electric motor, assists the drive of the hydraulic motor with the electric motor when the turning mechanism is accelerated, performs regenerative operation with the electric motor when the turning mechanism decelerates, A hydraulic excavator that charges a battery with generated electric power has been proposed (see, for example, Patent Document 1).

Also, an electric motor is provided as a power source of the turning mechanism for turning the upper turning body, and the generated electric power is generated by performing a power running operation (acceleration) and a regenerative operation (deceleration) with the electric motor when the turning mechanism is driven. Has been proposed (see, for example, Patent Document 2).

JP-A-10-103112 JP 2005-299102 A

In hybrid type work machines, power consumption due to an electric load such as a motor generator and generation of regenerative power are repeatedly performed, so that the voltage value of the DC bus between the electric load and the battery varies greatly. When the voltage value of the DC bus fluctuates, there is a risk of causing variations in load controllability, damage to the driver of the load due to overcurrent, and the like.

Also, in the hybrid type work machine, the rated output differs because the required driving force differs between the electric motor for assisting the engine and the electric motor for turning driving. Since an electric motor for assisting an engine performs an electric driving (assist) operation or a power generation operation at a substantially constant rotational speed, fluctuations in the output of the electric motor are relatively small. On the other hand, the electric motor for turning driving repeatedly performs acceleration (power running operation) and deceleration (regenerative operation) with the rotation of the upper turning body. Further, since the lever operation amount of the driver is changed depending on the work content, the rotation speed of the electric motor for turning driving is also changed accordingly. For this reason, if the supply voltage is changed according to the rotational speed of the electric motor for turning driving, a large voltage load is applied to the inverter (controller) of the motor generator that uses only a certain voltage range, resulting in damage or breakage. There is a fear. On the other hand, when the voltage value is adjusted to a motor generator that rotates only at a constant rotational speed, the output of the electric motor for turning drive becomes insufficient.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a hybrid work machine that suppresses variations in load controllability and damage to a load driver due to overcurrent by stabilizing the DC bus voltage value. And

It is another object of the present invention to provide a hybrid work machine using a step-up / down converter that can efficiently drive each electric motor while suppressing damage or breakage of the electric drive device.

According to one embodiment of the present invention, a plurality of inverters for driving a plurality of electric work elements, a capacitor that transfers power to and from the plurality of inverters, and a DC connected to the plurality of inverters And a buck-boost converter disposed between the DC bus and the battery, wherein the plurality of inverters include a first inverter and a second inverter, and the DC bus includes the A first DC bus to which the first inverter is connected; and a second DC bus to which the second inverter is connected. The step-up / down converter includes: the first DC bus and the capacitor; A hybrid work machine is provided that is disposed between the two.

According to another embodiment of the present invention, it is mechanically connected to an internal combustion engine for driving a hydraulic pump that generates a hydraulic pressure required for driving a hydraulically driven working element, and performs an electric (assist) operation and a power generation operation. A motor generator, an electric drive unit for driving an electric drive working element, and electric power to be supplied to the motor generator or the electric drive unit are accumulated, and is generated by the motor generator or the electric drive unit. A capacitor for charging the electric power, and one side is connected to the motor generator via the first DC bus, and the other side is connected to the capacitor to boost or step down the voltage value of the first DC bus. A first step-up / step-down converter, and one side connected to the electric drive unit via a second DC bus and the other side connected to the capacitor to boost or step down the voltage value of the second DC bus 2 buck-boost converter Hybrid operating machine is provided, characterized in that it comprises a.

According to the present invention, by stabilizing the DC bus voltage value, it is possible to suppress variations in load controllability, damage to the driver of the load due to overcurrent, and the like. In addition, each electric motor can be efficiently driven while suppressing damage or breakage of the electric drive device.

1 is a side view showing a hybrid work machine according to a first embodiment. It is a block diagram showing the structure of the hybrid type working machine by 1st Embodiment. It is a figure which shows roughly the circuit structure of the buck-boost converter used for the hybrid type working machine by 1st Embodiment. It is a control block diagram which shows the circuit structure of the drive control part of the buck-boost converter used for the hybrid type work machine of 1st Embodiment. FIG. 7 is a control block diagram of a circuit configuration of a drive control unit of a buck-boost converter used in a hybrid work machine according to a modification of the first embodiment. It is a figure which shows the current limiting method in the hybrid type work machine by 1st Embodiment, and is a characteristic view which shows the relationship between a battery current allowable value, a battery current value, and a current value (DC bus current value) flowing through the DC bus It is. It is a figure which shows the electric current limiting method in the hybrid type work machine of 1st Embodiment, and is a characteristic figure which shows the DC bus electric current value and the electric current value which each flows into an inverter. It is a block diagram showing the structure of the hybrid type working machine by 2nd Embodiment. It is a block diagram showing the structure of the hybrid type working machine by 3rd Embodiment. It is a block diagram showing the structure of the hybrid type working machine by 4th Embodiment. It is a figure which shows roughly the circuit structure of the buck-boost converter used for the hybrid type working machine by 4th Embodiment. It is a flowchart which shows the process sequence of the drive control of the bypass circuit performed by the buck-boost converter of the hybrid type work machine of 4th Embodiment.

Hereinafter, embodiments in which the present invention is applied to a hybrid work machine will be described.

(First embodiment)
FIG. 1 is a side view of a hybrid work machine according to a first embodiment of the present invention. An upper swing body 3 is mounted on the lower traveling body 1 of the hybrid work machine via a swing mechanism 2. In addition to the boom 4, the arm 5, and the lifting magnet 6, and the boom cylinder 7, arm cylinder 8, and bucket cylinder 9 for hydraulically driving them, the upper swing body 3 is equipped with a cabin 10 and a power source. The

"overall structure"
FIG. 2 is a block diagram illustrating the configuration of the hybrid work machine according to the first 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.

The engine 11 as a mechanical drive unit and the 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 hybrid work machine according to the first embodiment. Connected to the control valve 17 are hydraulic motors 1A (for right) and 1B (for left), a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9 for the lower traveling body 1 via a high-pressure hydraulic line.

The motor generator 12 is connected to a battery 19 as a battery via an inverter 18A and a step-up / down converter 100. The inverter 18A and the step-up / down converter 100 are connected by a DC bus 110. The lifting magnet 6 is connected to the DC bus 110 via an inverter 18B. The lifting magnet 6 includes an electromagnet that generates a magnetic force for magnetically attracting a metal object, and power is supplied from the DC bus 110 via the inverter 18B.

Further, a turning electric motor 21 is connected to the DC bus 110 via an inverter 20. The turning electric motor 21 is a power source of the turning mechanism 2 and performs drive control for rotating the upper turning body 3 in the right direction or the left direction. The DC bus 110 is arranged to transfer power between the battery 19, the lifting magnet 6, the motor generator 12, and the turning electric motor 21.

The DC bus 110 is provided with a DC bus voltage detection unit 111 for detecting a voltage value of the DC bus 110 (hereinafter referred to as a DC bus voltage value in the first embodiment). The detected DC bus voltage value is input to the controller 30.

The battery 19 is provided with a battery voltage detector 112 for detecting a battery voltage value and a battery current detector 113 for detecting a battery current value. The battery voltage value and battery current value detected by these are input to the controller 30.

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

The control device 17 and a pressure sensor 29 as a lever operation detection unit are connected to the operation device 26 via hydraulic lines 27 and 28, respectively. Connected to the pressure sensor 29 is a controller 30 that performs drive control of the electrical system of the construction machine of the first embodiment.

The above-described hybrid work machine is a hybrid work 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 operation of the hybrid work machine.

The motor generator 12 is an electric motor capable of both electric (assist) operation and power generation operation. In the present embodiment, a motor generator that is AC driven by an inverter 18 </ b> A is used as the motor generator 12. The motor generator 12 can be constituted by, for example, an IPM (Interior / Permanent / Magnet) 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.

Reduction gear 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. A 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 an electric driving (assist) 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 of the engine 11 is small, the driving force of the engine 11 is transmitted to the motor generator 12 through the speed reducer 13, so that the motor generator 12 generates power by the power generation operation. Switching between the electric operation and the power generation 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 18A is provided between the motor generator 12 and the buck-boost converter 100 as described above, and controls the operation of the motor generator 12 based on a command from the controller 30. Thus, when the inverter 18A controls the power running of the motor generator 12, the necessary power is supplied from the battery 19 and the step-up / down converter 100 to the motor generator 12 via the DC bus 110. Further, when the regeneration control of the motor generator 12 is being controlled, the battery 19 is charged with the electric power generated by the motor generator 12 via the DC bus 110 and the step-up / down converter 100.

The inverter 18B is provided between the lifting magnet 6 and the buck-boost converter 100, and supplies the requested power to the lifting magnet 6 from the DC bus 110 when the electromagnet is turned on based on a command from the controller 30. To do. Further, when the electromagnet is turned off, the regenerated electric power is supplied to the DC bus 100.

The battery 19 is connected to the inverter 18A, the inverter 18B, and the inverter 20 through the buck-boost converter 100. Thereby, the battery 19 excites (turns on) the lifting magnet 6 when at least one of the electric (assist) operation of the motor generator 12 and the power running operation of the turning electric motor 21 is performed. ) Supply the necessary power. The battery 19 generates regenerative power when at least one of the generator operation of the motor generator 12 and the regenerative operation of the turning motor 21 is performed, or when the lifting magnet 6 is demagnetized (turned off). During the operation, the electric power generated by the power generation operation or the regenerative operation is stored as electric energy.

Since the motor generator 12, the lifting magnet 6, and the turning motor 21 are connected to the DC bus 110 via the inverters 18A, 18B, and 20, the electric power generated by the motor generator 12 is received. In some cases, the lifting magnet 6 or the turning electric motor 21 may be directly supplied. Further, the electric power regenerated by the lifting magnet 6 may be supplied to the motor generator 12 or the turning electric motor 21. Further, the electric power regenerated by the turning electric motor 21 may be supplied to the motor generator 12 or the lifting magnet 6.

The charge / discharge control of the battery 19 includes the charge state of the battery 19, the operation state of the motor generator 12 (electric (assist) operation or power generation operation), the drive state of the lifting magnet 6, and the operation state of the turning motor 21 (power running operation or This is performed by the step-up / down converter 100 based on the regenerative operation. Switching control between the step-up / step-down operation of the step-up / step-down converter 100 is performed by controlling the DC bus voltage value detected by the DC bus voltage detection unit 111, the battery voltage value detected by the battery voltage detection unit 112, and the battery current detection unit 113. Is performed by the controller 30 based on the battery current value detected by.

The inverter 20 is provided between the turning electric motor 21 and the step-up / down converter 100 as described above, and performs operation control on the turning electric motor 21 based on a command from the controller 30. Thereby, when the inverter is operating and controlling the power running of the turning electric motor 21, necessary electric power is supplied from the battery 19 to the turning electric motor 21 through the step-up / down converter 100. 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 via the step-up / down converter 100.

The buck-boost converter 100 is connected to the motor generator 12, the lifting magnet 6, and the turning motor 21 via the DC bus 110 on one side, and connected to the battery 19 on the other side, so that the DC bus voltage value is constant. Control is performed to switch between step-up and step-down so as to be within the range.

When the motor generator 12 performs an electric (assist) operation, it is necessary to supply electric power to the motor generator 12 via the inverter 18A, and thus it is necessary to boost the DC bus voltage value. On the other hand, when the motor generator 12 performs a power generation operation, it is necessary to charge the generated power to the battery 19 via the inverter 18A, and thus it is necessary to step down the DC bus voltage value.

This also applies to the excitation (on) and demagnetization (off) of the lifting magnet 6 and the power running operation and regenerative operation of the turning electric motor 21. The operation state of the motor generator 12 is switched according to the load state of the engine 11, the driving state (excitation and demagnetization) of the lifting magnet 6 is switched in the working state, and the turning motor 21 is turned by the upper turning body 3. The operating state is switched according to the operation.

For this reason, the motor generator 12, the lifting magnet 6, and the turning motor 21 are supplied with power via the DC bus 110, and the power supply to the DC bus 110 can be generated from any of them. . For this reason, the step-up / step-down converter 100 switches between the step-up operation and the step-down operation so that the DC bus voltage value falls within a certain range in accordance with the operating state of the motor generator 12, the lifting magnet 6, and the turning electric motor 21. Take control.

The DC bus 110 is disposed between the three inverters 18A, 18B, and 20 and the step-up / down converter, and power is transferred between the battery 19, the motor generator 12, the lifting magnet 6, and the turning motor 21. Give and receive.

The DC bus voltage detection unit 111 is a voltage detection unit for detecting a DC bus voltage value. The detected DC bus voltage value is input to the controller 30, and is used for switching control between the step-up operation and the step-down operation for keeping the DC bus voltage value within a certain range.

The battery voltage detection unit 112 is a voltage detection unit for detecting the voltage value of the battery 19, and is used for detecting the state of charge of the battery. The detected battery voltage value is input to the controller 30 and used for switching control between the step-up / step-down operation of the step-up / step-down converter 100.

The battery current detection unit 113 is a current detection unit for detecting the current value of the battery 19. As the battery current value, a current flowing from the battery 19 to the step-up / down converter 100 is detected as a positive value. The detected battery current value is input to the controller 30 and used for improving the responsiveness of the step-up / step-down control of the step-up / step-down converter 100.

The turning electric motor 21 is an electric motor capable of both a power running operation and a regenerative operation, and is provided to drive 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. In the present embodiment, a motor that is AC driven by the inverter 20 using a PWM (Pulse Width Modulation) control signal is used as the turning electric motor 21. 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 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. By detecting the difference between the position and the rotation position after the left rotation or the right rotation, the rotation angle and the rotation direction of the rotation shaft 21A are detected. 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. Moreover, although the resolver 22 is attached in the example shown in FIG. 2, you may use the inverter control system which does not have a rotation sensor of an electric motor.

The mechanical brake 23 is a braking device that generates a mechanical braking force, and mechanically stops the rotating shaft 21A of the turning electric motor 21. This mechanical brake 23 is switched between braking and release by an electromagnetic switch. This switching is performed by the controller 30.

The turning speed reducer 24 is a speed reducer that mechanically transmits to the turning mechanism 2 by reducing the rotational speed of the rotating shaft 21A of the turning electric motor 21. Thereby, in the power running operation, the rotational force of the turning electric motor 21 can be increased and transmitted to the turning body as a larger rotational force. On the contrary, during the regenerative operation, the number of rotations generated in the revolving structure can be increased, and more rotational motion can be generated in the turning electric motor 21. The turning mechanism 2 can turn in a state where the mechanical brake 23 of the turning electric motor 21 is released, whereby the upper turning body 3 is turned leftward or rightward.

The operating device 26 is an operating device for operating the turning electric motor 21, the lower traveling body 1, the boom 4, the arm 5, and the lifting magnet 6, and is operated by a driver of the hybrid work machine. The operating device 26 converts the hydraulic pressure (primary hydraulic pressure) supplied through the pilot line 25 into a 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 the operation device 26 is operated, the control valve 17 is driven through the hydraulic line 27, thereby controlling the hydraulic pressure in the hydraulic motors 1 </ b> A and 1 </ b> B, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9. The lower traveling body 1, the boom 4, the arm 5, and the lifting magnet 6 are driven.

The hydraulic line 27 supplies hydraulic pressures necessary for driving the hydraulic motors 1A and 1B, the boom cylinder 7, the arm cylinder 8 and the bucket cylinder 9 to the control valve.

When the operation for turning the turning mechanism 2 is input to the operating device 26, the pressure sensor 29 as the turning operation detecting unit detects the operation amount as a change in the hydraulic pressure in the hydraulic line 28. The pressure sensor 29 outputs an electrical signal indicating the hydraulic pressure in the hydraulic line 28. Thereby, the operation amount for turning the turning mechanism 2 input to the operating device 26 can be accurately grasped. This electric signal is input to the controller 30 and used for driving control of the turning electric motor 21. In this embodiment, a pressure sensor is used as the lever operation detection unit. However, a sensor that reads an operation amount for turning the turning mechanism 2 input to the operating device 26 as it is may be used as it is.

"Controller 30"
The controller 30 is a control device that performs drive control of the hybrid work machine according to the present embodiment. The controller 30 includes a turning drive control unit 40 and a drive control unit 50, and is configured by an arithmetic processing unit including a CPU (Central Processing Unit) and an internal memory. The controller 30 functions as a control device when the CPU executes a drive control program stored in the internal memory.

The turning drive control unit 40 converts a signal representing an operation amount for turning the turning mechanism 2 among the signals input from the pressure sensor 29 into a speed command, and performs drive control of the turning electric motor 21.

The drive control unit 50 controls the operation of the motor generator 12 (switching between electric (assist) operation or power generation operation), drive control of the lifting magnet 6 (switching between excitation (on) and demagnetization (off)), and step-up / down pressure It is a control device for performing charge / discharge control of the battery 19 by controlling the drive of the converter 100. The drive control unit 50 includes a state of charge of the battery 19, an operation state of the motor generator 12 (electric (assist) operation or power generation operation), a drive state of the lifting magnet 6 (excitation (on) and demagnetization (off)), and turning Based on the operation state (powering operation or regenerative operation) of the motor 21, the switching operation between the step-up / step-down converter 100 and the step-down operation is performed, whereby the charge / discharge control of the battery 19 is performed.

Switching control between the step-up / step-down operation of the buck-boost converter 100 is performed by the DC bus voltage value detected by the DC bus voltage detection unit 111, the battery voltage value detected by the battery voltage detection unit 112, and the battery current detection unit 113. This is performed based on the detected battery current value.

FIG. 3 is a diagram schematically showing a circuit configuration of a step-up / down converter used in the hybrid work machine of the present embodiment. The buck-boost converter 100 includes a reactor 101, a boosting IGBT (Insulated Gate Bipolar Transistor) 102A, a step-down IGBT 102B, a power connection terminal 103 for connecting the battery 19, an output terminal 104 for connecting a load 106, and a pair A smoothing capacitor 105 inserted in parallel with the output terminal 104. The output terminal 104 of the buck-boost converter 100 and the load 106 are connected by a DC bus 110. The battery 19 corresponds to the battery 19 in FIG. 2, and the load 106 corresponds to the motor generator 12, the lifting magnet 6, and the turning electric motor 21 in FIG. 2. In FIG. 3, the inverters 18A, 18B, and 20 (see FIG. 2) are omitted for simplification of the drawing. Further, the drive control unit 50 that PWM-drives the step-up IGBT 102A and the step-down IGBT 102B is omitted.

Reactor 101 has one end connected to an intermediate point between boosting IGBT 102A and step-down IGBT 102B, and the other end connected to power supply connection terminal 103, so that induced electromotive force generated when ON / OFF of boosting IGBT 102A is generated. It is provided for supplying to the DC bus 110.

The step-up IGBT 102A and the step-down IGBT 102B are semiconductor elements that are composed of bipolar transistors in which MOSFETs (Metal Oxide Semiconductors Field Effect Transistors) are incorporated in the gate portion and can perform high-power high-speed switching. The step-up IGBT 102A and the step-down IGBT 102B are driven by applying a PWM voltage to a gate terminal from a drive control device for a step-up / down converter described later. Diodes 102a and 102b, which are rectifier elements, are connected in parallel to the step-up IGBT 102A and the step-down IGBT 102B.

The battery 19 may be a chargeable / dischargeable battery so that power can be exchanged with the DC bus 110 via the buck-boost converter 100. 3 shows the battery 19 as a capacitor, the capacitor 19 may be replaced with a capacitor, a chargeable / dischargeable secondary battery, or another form of power source capable of power transfer. Good.

The power connection terminal 103 and the output terminal 104 may be terminals that can be connected to the battery 19 and the load 106. A battery voltage detection unit 112 that detects a battery voltage is connected between the pair of power connection terminals 103. A DC bus voltage detector 111 that detects a DC bus voltage is connected between the pair of output terminals 104.

The battery voltage detection unit 112 detects the voltage value (vbat_det) of the battery 19, and the DC bus voltage detection unit 111 detects the voltage of the DC bus 110 (hereinafter, DC bus voltage: vdc_det).

The load 106 connected to the output terminal 104 is an electric load that can be driven by electric power supply and can generate electric power by regeneration. For example, the load 106 includes an IPM (InteriorInPermanent Magnetic) motor in which a magnet is embedded in a rotor or a lifting magnet. be able to. Although FIG. 3 shows a load 106 for direct current drive, an electric load driven by alternating current through an inverter may be used.

The smoothing capacitor 105 is an electric storage element that is inserted between the positive terminal and the negative terminal of the output terminal 104 and can smooth the DC bus voltage.

The battery current detection unit 113 may be any detection means capable of detecting the value of the current flowing through the battery 19 and includes a current detection resistor. The reactor current detection unit 108 detects a current value (ibat_det) flowing through the battery 19.

"Buck-boost operation"
In the buck-boost converter 100 having the above-described configuration, when boosting the DC bus 110, a PWM voltage is applied to the gate terminal of the boosting IGBT 102A, and the boosting voltage is increased via the diode 102b connected in parallel to the step-down IGBT 102B. The induced electromotive force generated in the reactor 101 when the IGBT 102A is turned on / off is supplied to the DC bus 110. Thereby, the DC bus 110 is boosted.

When the DC bus 110 is stepped down, a PWM voltage is applied to the gate terminal of the step-down IGBT 102B, and regenerative power generated by the load 106 is supplied from the DC bus 110 to the battery 19 via the step-down IGBT 102B. . As a result, the power stored in the DC bus 110 is charged in the battery 19 and the DC bus 110 is stepped down.

In FIG. 3, the drive control unit 100 that PWM-drives the step-up IGBT 102A and the step-down IGBT 102B is omitted, but the drive control unit 50 can be realized by either an electronic circuit or an arithmetic processing unit.

Here, the output torque of the turning electric motor 21 is proportional to the square of the voltage value supplied to the turning electric motor 21. For this reason, if the voltage value supplied to the electric motor 21 for rotation falls, output torque will fall significantly. For this reason, a large amount of current is required to output a torque based on a command from the operating device 26. However, in a hybrid work machine that continuously operates, the battery 130 cannot generate a current exceeding the rated current value due to heat generation. The output is insufficient and the work is interrupted.

Therefore, in order to keep the supply voltage to the turning electric motor 21 constant, it is desirable to keep the DC bus voltage value constant by voltage control. The same applies to the case of being supplied to the lifting magnet 6. Therefore, a voltage control method in converter 100 will be described with reference to FIG. 4 in order to maintain the voltage of DC bus 110.

FIG. 4 is a diagram showing the circuit configuration of the drive control unit 50 of the buck-boost converter 100 used in the hybrid work machine of the present embodiment in a control block. As shown in FIG. 4, the drive control unit 50 of the step-up / down converter 100 includes a voltage control unit 51 and a step-up / down switching unit 52.

The drive control unit 50 is connected to a power connection terminal 103, an output terminal 104, a step-up PM (Power module) 53, and a step-down PM 54. These are connected so that the hardware configuration shown in FIG. 3 can be realized. That is, the boost control IGBT 53A and the step-down IGBT 102B included in the step-up PM 53 and the step-down PM 54 are PWM-driven by the drive control unit 50. As a result, the battery voltage value Vbat (= vbat_det) and the battery current value Ibat (= Ibat_det) is output, and the DC bus voltage value Vout (= vdc_det) is output from the output terminal 104.

The voltage control unit 51 drives the step-up IGBT 102A and the step-down IGBT 102B by performing PI (Proportional Integral) control based on the difference between the target voltage value Vout_ref and the DC bus voltage value Vout output from the output terminal 104. The switching duty duty_ref for control is calculated.

Here, in the step-up / down converter 100 of the present embodiment, the switching duty for driving the step-up IGBT 102A and the switching duty for driving the step-down IGBT 102B are distinguished from each other by using different signs. For this reason, the switching duty described above is given a positive sign for driving the step-up IGBT 102A and given a negative sign for driving the step-down IGBT 102B.

Here, Vout_I is a voltage integral value calculated by the voltage control unit 51, and Vout_P is a voltage proportional value calculated by the voltage control unit 51. The duty_ref is a switching duty calculated by the voltage control unit 51 and is transmitted to the step-up / step-down switching unit 52 as a driving duty duty_ref. The drive duty duty_ref is given a positive sign for the drive duty for boost drive and a negative sign for the drive duty for step-up / step-down drive.

The step-up / step-down switching unit 52 determines the power module driven by the driving duty duty_ref as either the boosting PM 53 or the step-down PM 54 based on the sign of the driving duty duty_ref.

The boosting PM 53 is a power module incorporating the above-described boosting IGBT 102A, a driving circuit for driving the boosting IGBT 102A, and a self-protection function.

Similarly, the step-down PM 54 is a power module that incorporates the step-down IGBT 102B described above, a drive circuit for driving the step-down IGBT 102B, and a self-protection function.

Although the reactor is not shown in FIG. 4, the battery current value Ibat output from the power connection terminal 103 is a current flowing through the reactor.

Further, as described above, since the negative drive duty duty_ref is transmitted from the step-up / down switching unit 52 to the step-down IGBT 102B included in the step-down PM 54, the sign is reversed (−1 times). ing.

Thus, according to the hybrid work machine according to the present embodiment, the DC bus voltage value is kept constant between the DC bus 110 and the battery 19 connected to the plurality of inverters (18A, 18B, and 20). Since the step-up / step-down converter 100 is controlled in this manner, the DC bus voltage value is kept substantially constant according to various drive states of the motor generator 12, the lifting magnet 6, and the turning motor 21. Is done.

In addition, by maintaining the DC bus voltage value substantially constant in this manner, it is possible to suppress variations in controllability of the electric load, damage to the inverter due to overvoltage, and the like, as well as a battery due to overvoltage (overcharge). 19 damage can be suppressed.

By the way, as shown in FIG. 4, in the voltage control based on the target voltage value (Vout_ref), the DC bus voltage value Vout (= vdc_det), and the battery voltage value Vbat (= vbat_det) of the DC bus 110, the hybrid work machine Depending on the specifications and the driving state of the load 106, a large amount of electric power is required for driving the load 106, and it may be better to monitor the current value flowing through the battery 19.

Therefore, in the present embodiment, in addition to the voltage control described above, current control as described below may be further performed to enhance protection of the battery 19.

FIG. 5 is a diagram illustrating a circuit configuration of the drive control unit 50 of the buck-boost converter 100 used in the hybrid work machine according to the modification of the first embodiment in a control block. As shown in this figure, the drive control unit 50 of the buck-boost converter 100 according to the first embodiment includes a current control unit 55 and a control switching unit 56 in addition to the voltage control unit 51 and the buck-boost switching unit 52.

In the control block shown in FIG. 5, the switching duty duty_v calculated by the voltage control unit 51 is set as the first switching duty duty_v.

The current control unit 55 performs PI control based on the difference between the current threshold value Ibat_ref and the battery current value Ibat output from the power supply connection terminal 103, thereby driving and controlling the step-up IGBT 102A and the step-down IGBT 102B. 2 Calculate the switching duty duty_i.

In the control block shown in FIG. 5, each of the first switching duty and the second switching duty is given a positive sign for driving the step-up IGBT 102A and given a negative sign for driving the step-down IGBT 102B.

The control switching unit 56 selectively switches either the voltage control unit 51 or the current control unit 55 so that the load of the reactor 101 or the load 106 (output terminal 104) is equal to or lower than a predetermined load. Specifically, when the drive control by the voltage control unit 51 is being performed, if the absolute value of the current flowing through the reactor 101 becomes larger than the current threshold, the drive control is switched to the current control unit 55. Further, when the drive control by the current control unit 55 is performed, if the terminal voltage value of the output terminal 104 becomes higher than the target voltage value, the drive control is switched to the voltage control unit 51.

Such switching between voltage control and current control is performed depending on whether the control switching unit 56 is connected to plus (+) (voltage control) or connected to minus (−) (current control).

Note that Vout_I is a voltage integral value calculated by the voltage control unit 51, duty_i is a second switching duty calculated by the current control unit 55, and Vout_P is a voltage proportional value calculated by the voltage control unit 51. Ibat_I is a current integrated value calculated by the current control unit 55, duty_v is a first switching duty calculated by the voltage control unit 51, and Ibat_P is a current proportional value calculated by the current control unit 55.

The control switching unit 56 uses one of the first switching duty obtained from the voltage control unit 51 and the second switching duty obtained from the current control unit 55 to drive the boosting PM 53 and the step-down PM 54. Select as duty_ref.

When the battery current value Ibat exceeds the power supply current threshold Ibat_ref, the selection is switched to drive control by the current control unit 55 (that is, the second switching duty), and the DC bus voltage value Vout returns to the output target voltage value Vout_ref. This is performed by returning to the drive control unit by the voltage control unit 51 (that is, the first switching duty).

The selected drive duty duty_ref is transmitted to the step-up / step-down switching unit 52. Since this driving duty duty_ref is either the first switching duty or the second switching duty, a positive sign is attached to the driving duty for boost driving, and the driving duty for step-up / down driving. Is assigned a negative sign.

The step-up / step-down switching unit 52 determines, based on the sign of the driving duty duty_ref transmitted from the control switching unit 56, the power module driven by this driving duty duty_ref as either the step-up PM53 or the step-down PM54.

Although the reactor is not shown in FIG. 5, the battery current value Ibat output from the power connection terminal 103 is a current flowing through the reactor.

6A and 6B are diagrams showing a current limiting method in the present embodiment. FIG. 6A is a characteristic diagram showing the relationship between the allowable battery current value Ibat_lim, the battery current value Ibat, and the current value (DC bus current value) Idc flowing through the DC bus 110. FIG. 6B is a characteristic diagram showing the DC bus current value Idc and the current value flowing through each of the inverters 18A, 18B, and 20.

The DC bus current value Idc shown in FIG. 6A is the sum of the currents flowing through the inverters 18A, 18B, and 20 shown in FIG. That is, as shown in FIG. 6B, the DC bus current value Idc is the sum of the current value I1 flowing through the inverter 18A, the current value I2 flowing through the inverter 18B, and the current value I3 flowing through the inverter 20. The following formula (1) is established.

Idc = I1 + I2 + I3 (1)
In the present embodiment, in addition to the voltage control by the control block shown in FIG. 4, as shown in FIG. 6A, current limitation may be performed so that the battery current value Ibat is equal to or less than the battery current allowable value Ibat_lim. Such current control can be realized, for example, by setting the current threshold value Ibat_ref to Ibat_lim. When this current control is performed, a region exceeding the battery current allowable value Ibat_lim shown in FIG. 6A is excluded from the operation region of the battery current value Ibat.

Here, assuming that the conversion efficiency in the buck-boost converter 100 is η, the DC bus voltage vdc_det detected by the voltage detector 111, the voltage value vbat_det of the battery 19 detected by the battery voltage detector 112, and the DC bus current value Idc are When used, the battery current value Ibat can be expressed by the following equation (2).

Ibat = 1 / η × (vdc_det / vbat_det) × Idc (2)
For this reason, current limitation is performed by the drive control unit 50 so that the battery current value Ibat represented by the expression (2) is equal to or less than the battery current allowable value Ibat_lim, thereby suppressing the overcurrent of the battery 19 (battery 19). can do. The battery current allowable value Ibat_lim may be set to a rated current value, for example. Thereby, the load demand in each drive unit is high, and the output of the battery is limited with respect to the current supplied to the inverters 18A, 18B, and 20, thereby preventing excessive charge / discharge of the battery. Can prevent abnormal fever. Thereby, the lifetime of a battery can be extended.

The current loss in the buck-boost converter 100 is represented by the product of the battery current value Ibat and the internal resistance of the buck-boost converter 100. According to the present embodiment, since the battery current value Ibat is relatively small by limiting the battery current value Ibat to be equal to or less than the battery current allowable value Ibat_lim, current loss in the buck-boost converter 100 can be reduced. it can.

Also, the output of the load 106 is proportional to the supplied voltage and proportional to the current value. Here, when increasing the output of the load 106, it is necessary to increase the voltage and / or current (or both). Therefore, if the output target voltage value Vout_ref of the DC bus voltage value is set relatively high, even if the battery current value Ibat is limited to the allowable battery current value Ibat_lim, the current loss in the buck-boost converter 100 is reduced. Meanwhile, the output of the load 106 can be increased efficiently.

In addition, although the motor generator 12, the lifting magnet 6, and the turning electric motor 21 are connected to the DC bus 110 via the inverters 18A, 18B, and 20, the working elements are the specifications of the hybrid work machine. It may be changed accordingly. For example, the inverter 18B and the lifting magnet 6 are not included in a hybrid work machine including a bucket instead of the lifting magnet 6. Further, when a generator is provided on the boom shaft, arm shaft, or the like, this generator may be connected to the DC bus 110 via an inverter.

(Second Embodiment)
According to the first embodiment described above, the voltage fluctuation of the DC bus can be suppressed. However, in order to more reliably suppress the voltage fluctuation of the DC bus, as in the second embodiment described below. The DC bus is preferably divided. That is, the second embodiment is a further development of the first embodiment described above.

FIG. 7 is a block diagram showing the configuration of the hybrid work machine according to the second embodiment. In FIG. 7, 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 solid line.

The hybrid work machine according to the second embodiment is different from the hybrid work machine according to the first embodiment in that the DC bus is divided into two (110A and 110B). Accordingly, the connection of the motor generator 12, the lifting magnet 6, and the turning electric motor 21 is also different from that of the first embodiment. Furthermore, the point provided with the generator 200 connected to the boom axis | shaft of the boom 4 as an electric load differs from 1st Embodiment. Other configurations are the same as those of the hybrid work machine according to the first embodiment, and the same components are denoted by the same reference numerals and the description thereof is omitted.

The motor generator 12, the lifting magnet 6, and the generator 200 are connected to the DC bus 110A via inverters 18A, 18B, and 18C. A turning motor generator 21 is connected to the DC bus 110 </ b> B via an inverter 20.

The generator 200 is connected to the boom shaft of the boom 4 shown in FIG. 1 and is a generator for boom regeneration that generates power when the boom 4 is hydraulically driven by the boom cylinder 7. The generated electric power is supplied as regenerative energy to the DC bus 110A via the inverter 18C.

In the drive control device for the hybrid work machine according to the second embodiment, the motor generator 12, the lifting magnet 6, the generator 200, and the turning motor 21 are connected to separate DC buses 110A and 110B. Further, a step-up / down converter 100 is connected between the DC bus 110 </ b> A and the battery 19.

Therefore, the motor generator 12, the lifting magnet 6, and the generator 200 exchange power with the step-up / down converter 100 via the DC bus 110A, and the turning motor 21 communicates with the DC bus 110B. Send and receive power at.

In this way, the electric power supply system of the motor generator 12 and the turning electric motor 21 is divided so that the supply voltages of the motor generator 12, the lifting magnet 6, and the generator 200 are constant, and each drive unit is This is for controlling with high accuracy.

The DC bus 110A is provided with a DC bus voltage detector 111 for detecting a voltage value of the DC bus (hereinafter referred to as a DC bus voltage value in the second embodiment). The detected DC bus voltage value is input to the controller 30.

A battery voltage detector 112 for detecting a battery voltage value is connected between the terminals of the battery 19 on which the buck-boost converter 100 is connected, and between the battery 19 and the buck-boost converter 100, A battery current detector 113 for detecting a battery current value flowing through the battery 19 via the step-up / down converter 100 is provided. The battery voltage value and converter current value detected by these are input to the controller 30.

Here, each detection unit will be described.

The DC bus voltage detection unit 111 is a voltage detection unit for detecting the voltage value of the DC bus 110A. The detected DC bus voltage value is input to the controller 30, and is used for switching control between the step-up operation and the step-down operation for keeping the DC bus voltage value within a certain range.

The battery voltage detection unit 112 is a voltage detection unit for detecting the voltage value of the battery 19, and is used for detecting the state of charge of the battery. The detected battery voltage value is input to the controller 30 and used for switching control between the step-up / step-down operation of the step-up / step-down converter 100.

The battery current detection unit 113 is a current detection unit for detecting a current value supplied to the battery 19 through the buck-boost converter 100. As the battery current value, a current flowing from the battery 19 to the step-up / down converter 100 is detected as a positive value. The detected battery current value is input to the controller 30 and used for improving the responsiveness of the step-up / step-down control of the step-up / step-down converter 100.

The hybrid work machine according to the present embodiment is a hybrid work machine that uses the engine 11, the motor generator 12, the lifting magnet 6, the generator 200, and the turning electric motor 21 as power sources. These power sources are mounted on the upper swing body 3 shown in FIG. Hereinafter, the configuration of each part different from the first embodiment will be described.

The inverter 18A is provided between the motor generator 12 and the buck-boost converter 100, and controls the operation of the motor generator 12 based on a command from the controller 30. Thus, when the inverter 18A controls the electric (assist) operation of the motor generator 12, the necessary power is supplied from the battery 19 and the step-up / down converter 100 to the motor generator 12 via the DC bus 110A. . Further, when the motor generator 12 is controlling the power generation operation, the electric power generated by the motor generator 12 is supplied to the DC bus 110 </ b> A and the step-up / down converter 100.

The inverter 18 </ b> C is provided between the generator 200 and the buck-boost converter 100 and performs drive control of the generator 200. Specifically, when the generator 200 performs a regenerative operation by raising or lowering the boom 4, the electric power generated by the generator 200 is supplied to the DC bus 110 </ b> A and the step-up / down converter 100.

The battery 19 is connected to the inverters 18A, 18B, and 18C via the buck-boost converter 100 on one end side (left side in the figure) and connected to the inverter 20 on the other end side (right side in the figure). Therefore, the battery 19 supplies necessary electric power when the motor generator 12 is electrically operated (assist), the lifting magnet 6 is excited, or the turning motor 21 is powered. In addition, when the motor generator 12 performs the power generation operation, the lifting magnet 6 demagnetization, the generator 200 regenerative operation, or the revolving motor 21 regenerative operation, the regenerative power is stored as electric energy.

Since the motor generator 12, the lifting magnet 6, and the generator 200 are connected to the DC bus 110A via inverters 18A, 18B, and 18C, the electric power generated by the motor generator 12 is lifted. The magnet 6 may be supplied directly. Further, the electric power regenerated by the generator 200 may be supplied to the motor generator 12 or the lifting magnet 6.

The charge / discharge control of the battery 19 is based on the charge state of the battery 19, the operation state of the motor generator 12 (electric (assist) operation or power generation operation), the driving state of the lifting magnet 6, and the power generation state of the generator 200. This is done by the buck-boost converter 100. Switching control between the step-up / step-down operation of the step-up / step-down converter 100 is performed by controlling the DC bus voltage value detected by the DC bus voltage detection unit 111, the battery voltage value detected by the battery voltage detection unit 112, and the battery current detection unit 113. Is performed by the controller 30 based on the battery current value detected by.

Since the turning electric motor 21 is directly connected to the battery 19 via the DC bus 110B, the voltage value of the DC bus 110B is equal to the charging voltage value of the battery 19, and the step-up / step-down control of the step-up / down converter 100 is performed. Is performed regardless of the operating state (powering operation or regenerative operation) of the electric motor 21 for turning.

The inverter 20 is directly provided between the turning electric motor 21 and the battery 19, and performs operation control on the turning electric motor 21 based on a command from the controller 30. When the inverter controls the power running operation of the turning electric motor 21, necessary electric power is supplied from the battery 19 to the turning electric motor 21. Further, when the regenerative operation of the turning electric motor 21 is controlled, the electric power generated by the turning electric motor 21 is supplied to the DC bus 110B.

The buck-boost converter 100 is connected to the motor generator 12, the lifting magnet 6, and the generator 200 via the DC bus 110 </ b> A and inverters 18 </ b> A to 18 </ b> C on one side, and connected to the battery 19 on the other side. The step-up operation or the step-down operation is switched according to the operation state (drive state) of the machine 12 and the lifting magnet 6 and the power generation state of the generator 200.

When the motor generator 12 performs an electric driving (assist) operation, it is necessary to supply electric power to the motor generator 12 via the inverter 18A, so the DC bus voltage value is increased. Also, when driving the lifting magnet 6, it is necessary to supply power to the lifting magnet 6 via the inverter 18 </ b> B, so that the DC bus voltage value is increased according to the rotational speed of the motor generator 12.

On the other hand, when the motor generator 12 performs a power generation operation, it is necessary to charge the battery 19 through the inverter 18A with the generated power, so the DC bus voltage value is lowered. Even when the lifting magnet 6 is demagnetized and regenerative power is obtained, it is necessary to charge the battery 19 via the inverter 18B, so the DC bus voltage value is lowered. Furthermore, even when power generation is performed by the power generator 200, the battery 19 needs to be charged with the generated power via the inverter 18C, so the DC bus voltage value is reduced.

For this reason, the step-up / down converter 100 is configured so that the voltage value of the DC bus 110 </ b> A falls within a certain range in accordance with the operation state (drive state) of the motor generator 12 and the lifting magnet 6 and the power generation state of the generator 200. Switches between step-up and step-down operation.

Thus, when the DC bus is divided into a plurality of parts, an inverter is connected to the DC bus to which a plurality of drive units are connected. Accordingly, as described with reference to FIG. 6, the load demand in each drive unit is high, and the output of the battery is limited with respect to the current flowing through the inverters 18A, 18B, and 20 so that it is excessive. It is possible to prevent charging / discharging of the battery and to prevent abnormal heat generation. Thereby, the lifetime of a battery can be extended.

Therefore, in this embodiment, the DC bus is divided into two, and the buck-boost converter 100 is connected to only one DC bus 110A. Since the DC bus is divided into two parts, the power handled by the DC bus is smaller than when all the electrical loads are connected to one DC bus, so that the capacity of the buck-boost converter can be reduced. .

In addition, the step-up / down converter 100 is connected to one DC bus 110A, and the DC bus voltage value is held substantially constant using the voltage value (battery voltage value) and current value (battery current value) of the battery 19. The voltage value of the DC bus 110B to which the step-up / step-down converter is not connected is compared with the case where the step-up / step-down converter is not connected to the DC bus 110A (that is, the step-up / step-down converter is not connected to either of the two DC buses 110A and 110B). Stable in each stage.

For this reason, according to the present embodiment, by dividing the DC bus into two and connecting the buck-boost converter 100 to only one of them, it is possible to provide a hybrid work machine that achieves both stable operation and cost reduction. it can.

In addition, since the voltage value of the DC bus 110A is held substantially constant in this way, not only the motor generator 12, the lifting magnet 6, and the generator 200 connected to the DC bus 110A, but also a step-up / down converter is provided. Variations in controllability of the turning electric motor 21 connected to the DC bus 110B that is not disposed, damage to the inverter due to overcurrent, and the like can be suppressed, and damage to the battery 19 can be suppressed. .

Further, according to the present embodiment, the step-up / step-down converter 100 is provided between the DC bus 110 </ b> A to which the lifting magnet 6 is connected and the battery 19. The lifting magnet 6 adsorbs a heavy metal article or the like by an electromagnetic attraction force for carrying work. Therefore, the lifting magnet 6 is connected to the DC bus 110A to which the buck-boost converter 100 is connected, thereby providing a stable electromagnetic attraction force. Since it can be generated, controllability variation can be suppressed and reliability can be improved.

In the present embodiment, the motor generator 12, the lifting magnet 6, and the generator 200 are connected to the DC bus 110A via the inverters 18A, 18B, and 18C, and the turning electric motor is connected to the DC bus 110B via the inverter 20. 21 is connected, but the work element may be changed according to the specifications of the hybrid work machine.

For example, the inverter 18B and the lifting magnet 6 are not included in a hybrid work machine having a bucket instead of the lifting magnet 6. Further, when a generator is provided on the arm shaft or the like instead of the boom shaft or in addition to the boom shaft, the generator may be connected to the DC bus 110A via an inverter.

Further, the step-up / step-down switching control of the step-up / down converter 100 may be performed together with the current control, as in the modification of the first embodiment (FIGS. 5 and 6A, 6B).

(Third embodiment)
FIG. 8 is a block diagram showing the configuration of the hybrid work machine according to the third embodiment. In FIG. 8, 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 solid line.

The hybrid work machine of the third embodiment is the same as the hybrid work machine of the second embodiment in that the DC bus is divided into two (110A and 110B), but the lifting magnet 6, The connection between the generator 200 and the buck-boost converter 100 is different from that of the second embodiment. Accordingly, the connection of the DC bus voltage detection unit 111, the battery voltage detection unit 112, and the battery current detection unit 113 is different from that of the second embodiment. Since other configurations are the same as those of the first embodiment and the hybrid work machine of 2, the same components are denoted by the same reference numerals, and description thereof is omitted.

The motor generator 12 is connected to the DC bus 110A via an inverter 18A. Further, the turning motor generator 21, the generator 200, and the lifting magnet 6 are connected to the DC bus 110B through inverters 20A, 20B, and 20C.

In the drive control device for the hybrid work machine of this embodiment, the motor generator 12, the turning electric motor 21, the generator 200, and the lifting magnet 6 are connected to separate DC buses 110A and 110B, and The buck-boost converter 100 is connected between the DC bus 110B and the battery 19.

Therefore, the motor generator 12 exchanges power with the step-up / down converter 100 via the DC bus 110A, and the turning motor 21, the generator 200, and the lifting magnet 6 pass through the DC bus 110B. Power is exchanged with the buck-boost converter 100B.

As described above, the power supply system of the motor generator 12 and the turning motor 21 is divided into the rated voltage values and ratings of the motor generator 12, the turning motor 21, the generator 200, and the lifting magnet 6. This is because the current values are greatly different, so that separate power supply is possible.

The DC bus 110B is provided with a DC bus voltage detection unit 111 for detecting a voltage value of the DC bus (hereinafter referred to as a DC bus voltage value in the third embodiment). The detected DC bus voltage value is input to the controller 30.

A battery voltage detector 112 for detecting a battery voltage value is connected between the terminals of the battery 19 on which the step-up / step-down converter 100 is connected, and between the battery 19 and the step-up / down converter 100. Is provided with a battery current detector 113 for detecting a battery current value flowing through the battery 19 via the step-up / step-down converter 100. The battery voltage value and converter current value detected by these are input to the controller 30.

Here, each detection unit will be described.

The DC bus voltage detection unit 111 is a voltage detection unit for detecting the voltage value of the DC bus 110B. The detected DC bus voltage value is input to the controller 30, and is used for switching control between the step-up operation and the step-down operation for keeping the DC bus voltage value within a certain range.

The battery voltage detection unit 112 is a voltage detection unit for detecting the voltage value of the battery 19, and is used for detecting the state of charge of the battery. The detected battery voltage value is input to the controller 30 and used for switching control between the step-up / step-down operation of the step-up / step-down converter 100.

The battery current detection unit 113 is a current detection unit for detecting a current value supplied to the battery 19 through the buck-boost converter 100. As the battery current value, a current flowing from the battery 19 to the step-up / down converter 100 is detected as a positive value. The detected battery current value is input to the controller 30 and used for switching control between the step-up / step-down operation of the step-up / down converter 100.

The hybrid work machine according to the present embodiment is a hybrid building work machine that uses the engine 11, the motor generator 12, the lifting magnet 6, the generator 200, and the turning electric motor 21 as power sources. These power sources are mounted on the upper swing body 3 shown in FIG. Hereinafter, the configuration of each part different from the first embodiment will be described.

The inverter 18A is provided between the motor generator 12 and the DC bus 110A, and controls the operation of the motor generator 12 based on a command from the controller 30. Thereby, when the inverter 18A controls the electric (assist) operation of the motor generator 12, necessary electric power is supplied from the battery 19 to the motor generator 12 via the DC bus 110A. Further, when controlling the power generation operation of the motor generator 12, the power generated by the motor generator 12 is supplied to the DC bus 110A.

The battery 19 is connected to the inverter 18A on one end side (left side in the figure) and connected to the inverters 20A, 20B, and 20C via the buck-boost converter 100 on the other end side (right side in the figure). Therefore, the battery 19 supplies necessary electric power when the motor generator 12 is electrically operated (assist), the lifting magnet 6 is excited, or the turning motor 21 is powered. In addition, when the motor generator 12 performs the power generation operation, the lifting magnet 6 demagnetization, the generator 200 regenerative operation, or the revolving motor 21 regenerative operation, the regenerative power is stored as electric energy.

Since the turning electric motor 21, the lifting magnet 6 and the generator 200 are connected to the DC bus 110B via inverters 20A, 20B and 20C, the electric power generated by the turning electric motor 21 is lifted. There are cases where the magnet 6 is directly supplied, electric power regenerated by the lifting magnet 6 is supplied to the turning electric motor 21, and electric power regenerated by the generator 200 is further supplied by the electric motor 21 for turning. In some cases, the lifting magnet 6 may be supplied.

The charge / discharge control of the battery 19 is based on the charge state of the battery 19, the operation state (powering operation or regenerative operation) of the turning electric motor 21, the driving state of the lifting magnet 6, and the power generation state of the generator 200. 100. Switching control between the step-up / step-down operation of the step-up / step-down converter 100 is performed by controlling the DC bus voltage value detected by the DC bus voltage detection unit 111, the battery voltage value detected by the battery voltage detection unit 112, and the battery current detection unit 113. Is performed by the controller 30 based on the converter current value detected by.

Since the motor generator 12 is directly connected to the battery 19 via the DC bus 110A, the voltage value of the DC bus 110A is equal to the charge voltage value of the battery 19, and the step-up / step-down control of the step-up / down converter 100 is performed. Is performed regardless of the operation state of the motor generator 12 (electric operation or power generation operation).

The inverter 20A is provided between the turning electric motor 21 and the DC bus 110B, and performs operation control on the turning electric motor 21 based on a command from the controller 30. When the inverter controls the power running operation of the turning electric motor 21, the necessary electric power is supplied from the battery 19 to the turning electric motor 21 via the DC bus 110 </ b> B. Further, when controlling the regenerative operation of the turning electric motor 21, the electric power generated by the turning electric motor 21 is supplied to the DC bus 110 </ b> B and the step-up / down converter 100.

The inverter 20B is provided between the lifting magnet 6 and the DC bus 110B. When the electromagnet is turned on based on a command from the controller 30, the required power is supplied to the lifting magnet 6 from the DC bus 110B. . When the electromagnet is turned off, the regenerated electric power is supplied to the DC bus 110B and the step-up / down converter 100.

The inverter 20C is provided between the generator 200 and the DC bus 110B and performs drive control of the generator 200. Specifically, when the generator 200 performs a regenerative operation by raising or lowering the boom 4, the electric power generated by the generator 200 is supplied to the DC bus 110 </ b> B and the step-up / down converter 100.

The buck-boost converter 100 has one side connected to the turning electric motor 21, the lifting magnet 6, and the generator 200 via the DC bus 110B and the inverters 20A to 20C, and the other side connected to the battery 19 for turning. The step-up operation or the step-down operation is switched according to the operation state (drive state) of the electric motor 21 and the lifting magnet 6 and the power generation state of the generator 200.

When the turning electric motor 21 performs a power running operation, it is necessary to supply electric power to the turning electric motor 21 via the inverter 20A, so the DC bus voltage value is increased. Also, when driving the lifting magnet 6, it is necessary to supply electric power to the lifting magnet 6 via the inverter 20 </ b> B, so that the DC bus voltage value is increased according to the rotational speed of the motor generator 12.

On the other hand, when the turning electric motor 21 performs the regenerative operation, it is necessary to charge the battery 19 with the generated electric power via the inverter 20A, so the DC bus voltage value is lowered. Even when the lifting magnet 6 is demagnetized and regenerative power is obtained, it is necessary to charge the battery 19 via the inverter 20B, so the DC bus voltage value is lowered. Furthermore, even when power generation is performed by the power generator 200, the battery 19 needs to be charged with the generated power via the inverter 20C, so the DC bus voltage value is reduced.

For this reason, the buck-boost converter 100 is configured so that the voltage value of the DC bus 110B falls within a certain range according to the operating state (driving state) of the turning electric motor 21 and the lifting magnet 6 and the power generation state of the generator 200. Switches between step-up and step-down operation.

Thus, when the DC bus is divided into a plurality of parts, an inverter is connected to the DC bus to which a plurality of drive units are connected. Accordingly, as described with reference to FIG. 6, the load requirement in each drive unit is high, and the output of the battery is limited with respect to the current that is supplied to the inverters 18A, 18B, 20. Charging / discharging can be prevented and abnormal heat generation can be prevented. Thereby, the lifetime of a battery can be extended.

As described above, according to the hybrid work machine according to the present embodiment, when the DC bus is divided into two, all electric loads are connected to one DC bus as in the first embodiment. Since the electric power handled by the DC bus becomes smaller than that, the capacity of the buck-boost converter can be reduced.

In addition, the step-up / down converter 100 is connected to one DC bus 110B, and the DC bus voltage value is held substantially constant using the voltage value (battery voltage value) and current value (battery current value) of the battery 19. The voltage value of the DC bus 110A to which the step-up / step-down converter is not connected is compared with the case where the step-up / step-down converter is not connected to the DC bus 110B (that is, the step-up / step-down converter is not connected to either of the two DC buses 110A and 110B). Stable in each stage.

For this reason, according to the present embodiment, by dividing the DC bus into two and connecting the buck-boost converter 100 to only one of them, it is possible to provide a hybrid work machine that achieves both stable operation and cost reduction. it can.

The DC bus 110A not provided with the step-up / down converter is connected to the motor generator 12 having a relatively small voltage fluctuation via the inverter 18A, and to the DC bus 110A to which the turning motor generator 21 having a large voltage fluctuation is connected. The voltage value of the bus 110B is held substantially constant by the step-up / down converter 100, so that not only the turning electric motor 21, the lifting magnet 6 and the generator 200 connected to the DC bus 110B but also the step-up / down converter is arranged. Variations in controllability of the motor generator 12 connected to the DC bus 110A that is not provided, damage to the inverter due to overcurrent, and the like can be suppressed, and damage to the battery 19 can be suppressed.

In addition, the control part of the drive control apparatus of the buck-boost converter used for the hybrid type work machine of this embodiment can be realized by either an electronic circuit or an arithmetic processing unit.

In the above-described embodiment, the motor generator 12 is connected to the DC bus 110A via the inverter 18A, and the turning electric motor 21, the lifting magnet 6, and the power generator are connected to the DC bus 110B via the inverters 20A, 20B, and 20C. Although the embodiment in which the machine 200 is connected has been described, the work elements may be changed according to the specifications of the hybrid work machine.

For example, the inverter 20B and the lifting magnet 6 are not included in a hybrid work machine having a bucket instead of the lifting magnet 6. Further, when a generator is provided on the arm shaft or the like instead of the boom shaft or in addition to the boom shaft, the generator may be connected to the DC bus 110B via an inverter.

Also, the step-up / step-down switching control of the step-up / down converter 100 may be performed together with the current control, similarly to the modification of the first embodiment (FIGS. 5 and 6).

In the above-described embodiment, the form using the PI control has been described. However, the control method is not limited to the PI control method, and hysteresis control, robust control, adaptive control, proportional control, integral control, gain scheduling control, Alternatively, sliding mode control may be used.

(Fourth embodiment)
The fourth embodiment of the present invention will be described below. In the hybrid work machine according to the fourth embodiment of the present invention, as in the hybrid work machine according to the second embodiment described above, a plurality of DC buses (two in the second embodiment) are provided to reduce the DC bus voltage. In addition to suppressing the fluctuations, voltage step-up / down converters are provided in each of the plurality of DC buses to suppress voltage fluctuations in all the DC buses.

FIG. 9 is a block diagram showing a configuration of a hybrid work machine according to the fourth embodiment of the present invention. 9, parts that are the same as the parts shown in FIG. 7 are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In FIG. 9, 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 solid line.

In the drive control apparatus for the hybrid type work machine according to the present embodiment, the motor generator 12 and the lifting magnet 6 for assisting the engine 11, the electric motor 21 for turning, and the generator 30 for boom regeneration are separate DC buses 110A. 110B, and separate DC- boost converters 100A and 100B are connected between the DC buses 110A and 110B and the battery 19.

Therefore, the motor generator 12 and the lifting magnet 6 exchange power with the step-up / down converter 100A via the DC bus 110A, and the turning motor 21 and the generator 30 move up and down via the DC bus 110B. Power is exchanged with pressure converter 100B. As described above, the power supply system of the motor generator 12 and the turning motor 21 is divided because the rated voltage value and the rated current value of the motor generator 12 and the turning motor 21 are greatly different, and thus the different power supply systems. This is to enable supply.

In this embodiment, the rated voltage of the motor generator 12 is 360 (V), and the rated voltage of the turning motor 21 is 300 to 400 (V). Therefore, the capacities of the buck-boost converter 100B and the DC bus 110B are set to capacities that can withstand higher voltages and larger currents than the buck-boost converter 100A and the DC bus 110A.

DC bus voltage detectors 111A and 111B for detecting the voltage values of the respective DC buses (hereinafter referred to as DC bus voltage values) are arranged on the DC buses 110A and 110B, respectively. The detected DC bus voltage value is input to the controller 120.

Battery voltage detectors 112A and 112B for detecting a battery voltage value are connected to the battery 19, and a converter current flowing in the buck- boost converters 100A and 100B is interposed between the battery 19 and the buck- boost converters 100A and 100B. Battery current detectors 113A and 113B for detecting values are provided. The battery voltage value and converter current value detected by these are input to the controller 120. The battery current value is given as the sum of the converter current values detected by battery current detectors 113A and 113B.

Here, each detection unit will be described.

The DC bus voltage detection unit 111A is a voltage detection unit for detecting the voltage value of the DC bus 110A. The detected DC bus voltage value is input to the controller 120, and is used for switching control between the step-up operation and the step-down operation for keeping the DC bus voltage value within a certain range.

Similarly, the DC bus voltage detection unit 111B is a voltage detection unit for detecting the voltage value of the DC bus 110B. The detected DC bus voltage value is input to the controller 120, and is used for switching control between the step-up operation and the step-down operation for keeping the DC bus voltage value within a certain range.

Battery voltage detectors 112A and 112B are voltage detectors for detecting the voltage value of the battery 19, and are used for detecting the state of charge of the battery. The detected battery voltage value is input to the controller 120 and used for switching control between the step-up / step-down operation of the step-up / step-down converters 100A and 100B.

The battery current detection unit 113A is a current detection unit for detecting the converter current value of the step-up / down converter 100A. The converter current value is detected as a positive value of the current flowing from the battery 19 to the buck-boost converter 100A. The detected converter current value is input to the controller 120 and used for switching control between the step-up / step-down converter 100A and the step-up / step-down operation.

Battery current detector 113B is a current detector for detecting the converter current value of buck-boost converter 100B. The converter current value is detected as a positive value of the current flowing from the battery 19 to the buck-boost converter 100B.

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

The control device 17 and a pressure sensor 29 as a lever operation detection unit are connected to the operation device 26 via hydraulic lines 27 and 28, respectively. The pressure sensor 29 is connected to a controller 120 that performs drive control of the electric system of the hybrid work machine according to the present embodiment.

The hybrid work machine according to the present embodiment is a hybrid work 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. Hereinafter, each part in an electric power supply system is demonstrated.

"Configuration of each part"
The inverter 18A is provided between the motor generator 12 and the buck-boost converter 100A as described above, and controls the operation of the motor generator 12 based on a command from the controller 120. Thus, when the inverter 18A controls the electric (assist) operation of the motor generator 12, the necessary power is supplied from the battery 19 and the step-up / down converter 100A to the motor generator 12 via the DC bus 110A. . Further, when controlling the power generation operation of the motor generator 12, the electric power generated by the motor generator 12 is supplied to the DC bus 110A and the step-up / down converter 100A.

The inverter 18B is provided between the lifting magnet 6 and the buck-boost converter 100A, and supplies the requested power to the lifting magnet 6 from the DC bus 110A when the electromagnet is turned on based on a command from the controller 120. To do. When the electromagnet is turned off, the regenerated electric power is supplied to the DC bus 100A.

The battery 19 is connected to the inverters 18A and 18B via the buck-boost converter 100A, and is connected to the inverters 20A and 20B via the buck-boost converter 100B. For this reason, the battery 19 is operated when at least one of the electric (assist) operation of the motor generator 12 and the power running operation of the turning electric motor 21 is performed, or when the lifting magnet 6 is driven. Supply the necessary power. Further, when the motor generator 12 is performing a power generation operation, when regenerative power is generated when the lifting magnet 6 is turned off, when the turning motor 21 is performing a regenerative operation, or When 30 is performing the power generation operation, it is a power source for accumulating regenerative power generated by the power generation operation or the regenerative operation as electric energy.

Since the motor generator 12 and the lifting magnet 6 are connected to the DC bus 110A via inverters 18A and 18B, the electric power generated by the motor generator 12 is directly supplied to the lifting magnet 6. There is also a case.

The charge / discharge control of the battery 19 includes the charge state of the battery 19, the operation state of the motor generator 12 (electric (assist) operation or power generation operation), the power generation state of the generator 30, the drive state of the lifting magnet 6, and This is performed by the step-up / down converters 100A and 100B based on the operation state (powering operation or regenerative operation) of the electric motor 21. The switching control between the step-up / step-down converters 100A and 100B is performed by a DC bus voltage value detected by the DC bus voltage detection units 111A and 111B, a battery voltage value detected by the battery voltage detection units 112A and 112B, And the controller 120 based on the converter current value detected by the battery current detectors 113A and 113B.

The inverter 20A is provided between the turning electric motor 21 and the step-up / down converter 100B as described above, and performs operation control on the turning electric motor 21 based on a command from the controller 120. Thereby, when the inverter is controlling the power running operation of the turning electric motor 21, necessary electric power is supplied from the battery 19 to the turning electric motor 21 via the step-up / down converter 100 </ b> B. Further, when the regenerative operation of the turning electric motor 21 is controlled, the electric power generated by the turning electric motor 21 is supplied to the DC bus 110B.

The inverter 20B is provided between the generator 30 and the buck-boost converter 100A, and performs drive control of the generator 30. Since the turning electric motor 21 is connected to the DC bus 110B via the inverter 20A, the electric power generated by the generator 30 may be directly supplied to the turning electric motor 21 in some cases.

The buck-boost converter 100A has one side connected to the motor generator 12 and the lifting magnet 6 via the DC bus 110A and inverters 18A and 18B, and the other side connected to the battery 19, and the motor generator 12 and the lifting magnet. The step-up operation or the step-down operation is switched according to the operation state (drive state) 6.

When the motor generator 12 performs an electric driving (assist) operation, it is necessary to supply electric power to the motor generator 12 via the inverter 18A, so the DC bus voltage value is increased. Also, when driving the lifting magnet 6, it is necessary to supply electric power to the lifting magnet 6 via the inverter 18 </ b> B, so that the DC bus voltage value is increased according to the rotational speed of the motor generator 12.

On the other hand, when the motor generator 12 performs a power generation operation, it is necessary to charge the battery 19 through the inverter 18A with the generated power, so the DC bus voltage value is lowered. For this reason, the step-up / step-down converter 100A performs a step-up operation or a step-down operation so that the voltage value of the DC bus 110A falls within a certain range according to the operation state (drive state) of the motor generator 12 and the lifting magnet 6. Switch.

Also, when the generator 30 generates power, the generated power needs to be charged to the battery 19 via the inverter 20B, so the DC bus voltage value is reduced.

Here, since the engine 11 is rotating at a constant rotational speed, the motor generator 12 is also rotated at a constant rotational speed, whereby the voltage value of the inverter 18A is controlled to be constant. Therefore, the motor generator 12 and the inverter 18A are connected to the DC bus 110A with little voltage fluctuation. Similarly, since the voltage value of the lifting magnet 6 is constant, the inverter 18B that controls the lifting magnet 6 is also connected to the DC bus 110A. As described above, since the DC bus 110A is connected to the drive unit having a small voltage fluctuation, the step-up / down converter 100A is configured so that the voltage value detected by the DC bus voltage detection unit 111A in the DC bus 110A is constant. The voltage values of the voltage detector 111A and the battery voltage detectors 112A and 112B are compared, and the power supply to the battery 19 is controlled.

On the other hand, the rotation speed of the turning electric motor 21 is larger than that of the motor generator 12 because it changes based on the lever operation amount of the operator corresponding to the work content. For this reason, the voltage value of the DC bus 110 </ b> B to be supplied to the turning electric motor 21 varies greatly according to the rotation speed of the turning electric motor 21. Therefore, when the turning electric motor 21 is connected to the DC bus 110A controlled to a constant voltage value, when the rotation speed of the turning electric motor 21 is high, the voltage value of the DC bus 110A is not sufficiently high. It becomes impossible to perform the turning operation. Moreover, if high voltage regenerative power is supplied from the swing motor 21 to the DC bus 110A, the inverter 18A is damaged.

Therefore, in this embodiment, the DC bus 110B and the buck-boost converter 100B are provided separately from the DC bus 110A and the buck-boost converter 100A that control the voltage value to be constant, so that each electric motor can be driven efficiently.

The buck-boost converter 100B has one side connected to the turning electric motor 21 via the DC bus 110B and the other side connected to the battery 19. The step-up / step-down converter 100 </ b> B switches the step-up operation or the step-down operation so that the voltage value of the DC bus 110 </ b> B corresponds to the turning speed detected by the resolver 22 connected to the turning electric motor 21. The step-up / down converter 100B sets the voltage value of the DC bus 110B to a value higher than the voltage value of the DC bus 110A. This is due to the difference in usage of the motor generator 12 and the turning electric motor 21.

As described above, the step-up / step-down converter 100B variably controls the voltage value of the DC bus 110B because the rotational speed of the turning motor 21 is considerably larger than that of the motor generator 12 during driving. This is because the voltage value of the DC bus 110B greatly fluctuates when performing regenerative operation. Note that switching of the step-up / step-down operation is performed by the controller 120.

Specifically, when the rotational speed detected by the resolver 22 is high, a high voltage is required for the DC bus 110B. In this case, the step-up / step-down converter 100B has a voltage between the DC bus voltage detection unit 111B and the battery voltage detection unit 112B so that the voltage detection value of the DC bus voltage detection unit 111B becomes a voltage value corresponding to the rotation speed at a high speed. The values are compared, and the power supply to the battery 19 is controlled.

When the rotational speed detected by the resolver 22 is low, a low voltage is sufficient for the DC bus 110B. In this case, since the overvoltage state occurs when the DC bus voltage is high, the step-up / down converter 100B is configured so that the voltage detection value of the DC bus voltage detection unit 111B becomes a voltage value corresponding to the low-speed rotation speed. The power supply to the battery 19 is controlled.

In the above description, the voltage value of the DC bus 110B changes based on the turning speed detected by the resolver 22, but the voltage value of the DC bus 110B is changed based on the speed command value corresponding to the lever operation amount of the driver. It may be changed.

For convenience of explanation, although not shown in FIG. 2, a bypass circuit is connected in parallel to the buck-boost converter 100B. This bypass circuit is a circuit for short-circuiting between the DC bus 110B and the battery 19 when the buck-boost converter 100B is abnormal, and details thereof will be described later with reference to FIG.

As described above, the DC bus voltage detection unit 111A and the DC bus voltage detection unit 111B are voltage detection units for detecting the voltage values of the DC bus 110A and the DC bus 110B. 112B is a voltage detection unit for detecting the voltage value of the battery 19, and the battery current detection unit 113A and the battery current detection unit 113B detect the converter current values of the step-up / down converter 100A and the step-up / down converter 100B. It is a current detection unit. The converter current value is detected as a positive value of the current flowing from the battery 19 to the buck- boost converters 100A and 100B.

FIG. 10 is a circuit diagram schematically showing the circuit configuration of the buck-boost converter used in the hybrid work machine of the present embodiment. Since the configuration of the step-up / step-down converters 100A and 100B is the same, the description will focus on the step-up / step-down converter 100A.

The step-up / down converter 100A includes a reactor 101, a boosting IGBT (Insulated Gate Bipolar Transistor) 102A, a step-down IGBT 102B, a power connection terminal 103A for connecting the battery 19, an output terminal 104A for connecting a load, and a pair of A smoothing capacitor 105 inserted in parallel with the output terminal 104A is provided. The output terminal 104A of the buck-boost converter 100A and the load are connected by a DC bus 110A.

The loads connected to the DC bus 110A are the motor generator 12, the generator 30, and the lifting magnet 6 connected in parallel to each other.

In FIG. 10, the inverters 18A to 18B (see FIG. 9) are omitted for simplification of the drawing. Further, the drive control unit 120A that PWM-drives the step-up IGBT 102A and the step-down IGBT 102B is omitted.

Further, the buck-boost converter 100A has a self-diagnosis function, and this self-diagnosis function is realized by the battery current detection unit 113A of the buck-boost converter 100A monitoring the current value. This self-diagnosis function may be realized by the step-up / down converter 100A monitoring the detection value of the battery current detection unit 113A.

Reactor 101 has one end connected to an intermediate point between boosting IGBT 102A and step-down IGBT 102B, and the other end connected to power supply connection terminal 103A. The induced electromotive force generated when boosting IGBT 102A is turned on / off is generated. It is provided to supply to the DC bus 110A.

The step-up IGBT 102A and the step-down IGBT 102B are semiconductor elements that are composed of bipolar transistors in which MOSFETs (Metal Oxide Semiconductors Field Effect Transistors) are incorporated in the gate portion and can perform high-power high-speed switching. The step-up IGBT 102A and the step-down IGBT 102B are driven by applying a PWM voltage from the drive control unit 120A to the gate terminal. Diodes 102a and 102b, which are rectifier elements, are connected in parallel to the step-up IGBT 102A and the step-down IGBT 102B.

The battery 19 may be a chargeable / dischargeable battery so that power can be exchanged with the DC bus 110A via the buck-boost converter 100A. 3 shows the battery 19 as a capacitor, the capacitor 19 may be replaced with a capacitor, a chargeable / dischargeable secondary battery, or another form of power source capable of power transfer. Good.

The power connection terminal 103A may be a terminal to which the battery 19 can be connected. The output terminal 104A may be any terminal to which the DC bus 110A can be connected.

The battery 19 is connected to battery voltage detectors 112A and 112B that detect the battery voltage. In addition, a DC bus voltage detection unit 111A that detects a DC bus voltage is connected to the DC bus 110A.

The battery voltage detectors 112A and 112B detect the voltage value of the battery 19, and the DC bus voltage detector 111A detects the voltage value of the DC bus 110A.

The smoothing capacitor 105 may be any storage element that is inserted between the positive terminal and the negative terminal of the output terminal 104A and can smooth the DC bus voltage of the DC bus 110A.

The battery current detection unit 113A may be any detection means capable of detecting the converter current value of the buck-boost converter 100A, and includes a current detection resistor.

The step-up / down converter 100B includes a reactor 101, a step-up IGBT (Insulated Gate Bipolar Transistor) 102A, a step-down IGBT 102B, a power connection terminal 103B for connecting the battery 19, an output terminal 104B for connecting a load, and a pair of A smoothing capacitor 105 inserted in parallel with the output terminal 104B is provided. The output terminal 104B of the buck-boost converter 100B and the load are connected by a DC bus 110B. The load connected to the DC bus 110 </ b> B is the turning electric motor 21. In FIG. 10, the inverter 20A (see FIG. 9) is omitted for simplification of the drawing.

Further, the buck-boost converter 100B has a self-diagnosis function, and this self-diagnosis function is realized by the battery current detector 113B of the buck-boost converter 100B monitoring the current value. This self-diagnosis function may be realized by monitoring the detection value of the battery current detection unit 113B by the buck-boost converter 100B.

Reactor 101 has one end connected to an intermediate point between boosting IGBT 102A and step-down IGBT 102B, and the other end connected to power supply connection terminal 103B. Reactor 101 generates induced electromotive force generated when ON / OFF of boosting IGBT 102A is generated. It is provided to supply to the DC bus 110B.

The configuration of the step-up IGBT 102A and the step-down IGBT 102B is the same as that of the step-up / down converter 100A.

The battery 19 exchanges power with the DC bus 110B via the step-up / down converter 100B.

The power connection terminal 103B may be any terminal to which the battery 19 can be connected. The output terminal 104B may be a terminal to which the DC bus 110B can be connected.

Further, a DC bus voltage detection unit 111B that detects a DC bus voltage is connected to the DC bus 110B. The DC bus voltage detection unit 111B detects the voltage value of the DC bus 110B.

The smoothing capacitor 105 may be any storage element that is inserted between the positive terminal and the negative terminal of the output terminal 104B and can smooth the DC bus voltage of the DC bus 110B.

The battery current detection unit 113B may be any detection means capable of detecting the converter current value of the buck-boost converter 100B, and includes a resistor for current detection.

Further, a bypass circuit 130 is connected in parallel to the buck-boost converter 100B. The bypass circuit 130 is a circuit for short-circuiting the DC bus 110B and the battery 19 when the buck-boost converter 100B is abnormal, and includes relays 130A and 130B that are controlled to open and close by the drive control unit 120A. The opening / closing control of the bypass circuit 130 will be described later.

"Buck-boost operation"
In such a step-up / down converter 100A, when boosting the DC bus 110A, a PWM voltage is applied to the gate terminal of the boosting IGBT 102A, and the boosting IGBT 102A is connected via the diode 102b connected in parallel to the step-down IGBT 102B. The induced electromotive force generated in the reactor 101 when the power is turned on / off is supplied to the DC bus 110A. As a result, the DC bus 110A is boosted. The same applies to the relationship between the step-up / down converter 100B and the DC bus 110B.

When the DC bus 110A is stepped down, a PWM voltage is applied to the gate terminal of the step-down IGBT 102B, and the generated power generated by the motor generator 12 or the generator 30 is generated via the step-down IGBT 102B. Is supplied to the battery 19 from the DC bus 110A. As a result, the electric power stored in the DC bus 110A is charged in the battery 19, and the DC bus 110A is stepped down. This step-down operation is the same between the step-up / down converter 100B and the turning motor generator 21 connected via the DC bus 110B.

FIG. 11 is a flowchart showing a processing procedure of drive control of the bypass circuit 130 performed by the step-up / down converter 100A of the hybrid work machine of this embodiment. This process is executed by the control unit of the buck-boost converter 100A.

The step-up / down converter 100A determines whether or not an abnormal signal is received from the step-up / down converter 100B (step S1). This process is repeatedly executed until an abnormal signal is received from the step-down converter 100B that performs abnormality determination using the self-diagnosis function.

When receiving the abnormal signal, the step-up / down converter 100A closes the relays 130A and 130B to turn on the bypass circuit 130 (step S2). Thereby, the buck-boost converter 100B is bypassed, and the DC bus 110B is directly connected to the battery 19.

Next, the buck-boost converter 100A sets the current limit value of the buck-boost converter 100A to the current limit value of the buck-boost converter 100B, and boosts the voltage to control the DC bus voltage values of both the DC buses 110A and 110B to be constant. Alternatively, a step-down operation is performed. Thereby, even if abnormality occurs in the buck-boost converter 100B and it cannot be used temporarily, the voltage of the battery 19 can be made constant by the system (inverter 18A or the like) on the DC bus 110A side. Thus, the DC bus 110B can maintain a voltage equivalent to the battery voltage, and can control the inverter 20A to drive the turning electric motor 21 until a predetermined operation is completed.

Here, although a description has been given of a mode in which drive control of the bypass circuit 130 is performed by the buck-boost converter 100A when abnormality determination is performed by the self-diagnosis function of the buck-boost converter 100B, the buck-boost converter 100B determines abnormality. When the operation is performed, an abnormality signal may be reported to the drive control unit 120A that is the host control unit, and the drive control unit 120A may perform drive control of the bypass circuit 130.

As described above, according to the hybrid work machine according to the present embodiment, the motor generator 12 and the lifting magnet 6 for assisting the engine 11, the electric motor 21 for turning and the boom regenerator for driving the turning mechanism 2 are used. Since the generator 30 is connected to separate DC buses 110A and 110B, electric power is supplied to the motor generator 12, the lifting magnet 6 and the turning motor 21 via separate DC buses 110A and 100B. Is done.

With such a configuration, the voltage value of the DC bus 110B can be set higher than the voltage value of the DC bus 110A in accordance with the difference in the rated output of the motor generator 12 with the rated output and the motor 21 for turning. It is possible to provide a hybrid work machine using a step-up / step-down converter that can efficiently drive each electric motor while suppressing damage or breakage.

Furthermore, since the DC bus and the step-up / down converter are divided into a plurality of parts, even if one of the step-up / step-down converters is damaged, all the work can be continued for a predetermined time with the other converter without immediately being out of control. .

Further, since the lifting magnet 6 and the turning electric motor 21 are connected by the common DC bus 110B, even if the buck-boost converter 100B is damaged, the current supply to the lifting magnet 6 can be continued immediately.

The hybrid work machine to which the present invention is applied may be a hybrid construction machine. In addition, the hybrid work machine to which the present invention is applied may be a work machine of a form other than a construction machine, and may be, for example, a hybrid transporting and handling machine (crane or forklift).

For example, the engine 11 and the motor generator 12 shown in FIG. 2 are used as the crane engine and the assist motor generator, and the turning electric motor 21 shown in FIG. 2 is used to raise or lower parts, cargo, etc. in the crane handling operation. Can be used as a power source. In particular, the power source for raising or lowering parts, cargo, etc., performs the power running operation (during winding) and regenerative operation (during withdrawal) accompanying the winding or drawing of the wire. It can be implemented in the same way as a machine.

Similarly, in the case of a forklift, the engine 11 and motor generator 12 shown in FIG. 2 are used as a forklift engine and an assist motor generator, and the turning electric motor 21 shown in FIG. Alternatively, it may be used as a power source for lowering. In particular, the power source for raising or lowering the fork performs a power running operation (at the time of winding) and a regenerative operation (at the time of pulling out) in accordance with the up and down movement, so that it can be implemented in the same manner as the above-described hybrid type work machine. it can.

The hybrid working machine according to the exemplary embodiment of the present invention has been described above, but the present invention is not limited to the specifically disclosed embodiment, and departs from the scope of the claims. Various modifications and changes are possible.

This application is based on Japanese Patent Application No. 2008-166448 filed on June 25, 2008 and Japanese Patent Application No. 2008-030773 filed on Feb. 12, 2008, the entire contents of which are incorporated herein by reference. Is done.

The present invention is applicable to a hybrid work machine having a power storage unit for supplying power.

DESCRIPTION OF SYMBOLS 1 Lower traveling body 1A, 1B Traveling mechanism 2 Turning mechanism 3 Upper turning body 4 Boom 5 Arm 6 Lifting magnet 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 10 Cabin 11 Engine 12 Motor generator 13 Decelerator 14 Main pump 15 Pilot pump 16 High pressure hydraulic line 17 Control valve 18A, 18B Inverter 20A, 20B Inverter 19 Battery 21 Electric motor for turning 22 Resolver 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 DESCRIPTION OF SYMBOLS 30 Controller 31 Speed command conversion part 32 Drive control apparatus 40 Turning drive control apparatus 50 Drive control part 51 Voltage control part 52 Buck-boost switching part 53 PM for boosting
54 PM for step-down
55 Current Control Unit 56 Control Switching Unit 100, 100A, 100B Buck-Boost Converter 101 Reactor 102A Boost IGBT
102B IGBT for step-down
103, 103A, 103B Power connection terminal 104, 104A, 104B Output terminal 105 Capacitor 106 Load 110, 110A, 110B DC bus 111, 111A, 111B DC bus voltage detector 112, 112A, 112B Battery voltage detector 113, 113A, 113B Battery current detection unit 120 controller 120A drive control unit 120B turning drive control unit

Claims (14)

1. A plurality of inverters for driving a plurality of electric work elements;
   A battery that exchanges power with the plurality of inverters;
   A DC bus connected to the plurality of inverters;
   A buck-boost converter disposed between the DC bus and the battery;
   The plurality of inverters includes a first inverter and a second inverter,
   The DC bus includes a first DC bus to which the first inverter is connected, and a second DC bus to which the second inverter is connected,
   The step-up / step-down converter is disposed between the first DC bus and the electric storage device.
2. A hybrid work machine according to claim 1,
   An inverter for driving and controlling a motor generator that assists the engine is connected to the first DC bus.
3. A hybrid work machine according to claim 2,
   The electric work element includes a boom electric motor for adjusting an angle of the boom, and an inverter for driving the boom electric motor is connected to the first DC bus. Hybrid type work machine.
4. A hybrid working machine according to any one of claims 1 to 3,
   The electric work element includes an electromagnet for a lifting magnet, and an inverter for driving the electromagnet is connected to the first DC bus.
5. A hybrid work machine according to claim 1,
   An inverter for driving and controlling a motor generator for assisting an engine is connected to the second DC bus.
6. A hybrid work machine according to any one of claims 1 to 5,
   Current detection means for detecting a current value flowing between the capacitor and the buck-boost converter;
   The step-up / down converter is controlled so that a current value detected by the current detection means is equal to or less than an allowable current value of the battery.
7. A motor generator mechanically connected to an internal combustion engine for driving a hydraulic pump that generates a hydraulic pressure necessary for driving a hydraulically driven working element, and performing an electric (assist) operation and a power generation operation;
   An electric drive unit for driving an electric drive working element;
   A battery for accumulating electric power to be supplied to the motor generator or the electric drive unit and charging electric power generated by the motor generator or the electric drive unit;
   A first step-up / step-down converter that has one side connected to the motor generator via a first DC bus and the other side connected to the capacitor, stepping up or down the voltage value of the first DC bus;
   A second step-up / step-down converter that has one side connected to the electric drive unit via a second DC bus and the other side connected to the capacitor and that steps up or down the voltage value of the second DC bus. A hybrid work machine characterized by that.
8. The hybrid work machine according to claim 7,
   The electric drive unit is a turning electric motor for rotationally driving the turning mechanism of the upper turning body,
   At least one of the first buck-boost converter and the second buck-boost converter variably controls the voltage value of the first DC bus or the second DC bus according to the rotational speed of the turning electric motor. A hybrid work machine characterized by that.
9. The hybrid work machine according to claim 7,
   The electric drive unit is a turning electric motor for rotationally driving the turning mechanism of the upper turning body,
   One of the first step-up / step-down converter and the second step-up / step-down converter variably controls the voltage value of the first DC bus or the second DC bus according to the rotational speed of the turning electric motor. The other of the first buck-boost converter and the second buck-boost converter controls the voltage value of the first DC bus or the second DC bus to a constant value. Work machine.
10. The hybrid work machine according to claim 9, wherein
    A driving circuit of a lifting magnet or a driving circuit of an electric traveling mechanism is connected to the first DC bus or the second DC bus whose voltage value is controlled to a constant value. Hybrid type work machine.
11. A hybrid work machine according to any one of claims 7 to 10,
    At least one of the first step-up / step-down converter and the second step-up / step-down converter has a self-diagnosis function, and in the event of an abnormality, an abnormal signal indicating the abnormality is reported to the other.
12. A hybrid work machine according to claim 11,
    When the first buck-boost converter or the second buck-boost converter detects an abnormality by a self-diagnosis function, the first buck-boost converter sets its own current limit value to the current limit value of the other buck-boost converter. Hybrid type work machine.
13. A hybrid work machine according to any one of claims 7 to 10,
    One of the first step-up / step-down converter and the second step-up / down converter has a self-diagnosis function, and at the time of abnormality, an abnormal signal indicating the abnormality is notified to the host control unit. machine.
14. A hybrid work machine according to any one of claims 7 to 13,
    At least one of the first buck-boost converter and the second buck-boost converter has a bypass circuit that bypasses its own buck-boost converter in the event of an abnormality.

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