JP2012112168A - Controller of electric motor, control method of electric motor and construction machine including controller of electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller of an electric motor, which does not make an operator feel discomfort even in an economy mode.SOLUTION: The controller of the electric motor having a power mode and the economy mode as an operation mode includes: first map storage means 49 for storing a first map of a torque limit corresponding to a revolving speed of a revolving superstructure corresponding to the power mode; and second map storage means 50 for storing a second map of the torque limit corresponding to the revolving speed of the revolving superstructure corresponding to the economy mode. In the case that the economy mode is selected when generating the torque limit of an electric motor 24 by using one of a first map 49 and a second map 50, when the revolving speed of the revolving superstructure detected in revolving speed detection means is equal to or lower than a prescribed speed, a torque limit command which is the same as the torque limit of the first map 50 or larger than the torque limit when exceeding the prescribed speed is generated.

Description

  The present invention relates to a motor control device, a motor control method, and a construction machine including the motor control device.

There are known hydraulic excavators in which a power mode that emphasizes work efficiency and an economy mode that emphasizes the fuel consumption rate are set.
The power mode is a mode in which the work machine is operated by increasing the output of the engine in order to increase work efficiency.
On the other hand, the economy mode is a mode in which the output of the engine is suppressed and the fuel consumption of the engine due to the operation of the work machine is reduced.
Here, a conventional hydraulic excavator drives a hydraulic pump with a power source of an engine, and drives a turning motor, a working machine cylinder, and a traveling motor with hydraulic oil discharged from the hydraulic pump.
Therefore, the conventional hydraulic excavator excavates the earth and sand with the bucket and turns the boom or arm while turning it (hoist operation), and the hydraulic oil flows to the swing motor and the hydraulic oil to the boom cylinder or arm cylinder. It works in balance with the flow of
That is, in the hoist turning, the work implement is lifted while excavating the earth and sand and turning, and the hoist is operated at a timing such that the rising stop point of the work implement coincides with the turning stop point. A typical example of the work by swivel hoist is a work of loading earth and sand on a loading platform of a dump truck by a hydraulic excavator.

By the way, in recent years, a hybrid type hybrid hydraulic excavator in which a rotating body is driven by an electric motor and a work machine and a traveling body are driven by a hydraulic actuator has been developed, and it is possible to set a power mode and an economy mode in the hybrid hydraulic excavator. is there.
However, the power source of the electric motor of the hybrid hydraulic excavator uses not the direct power from the engine but the power from the generator or the capacitor.
For this reason, when hoist turning is performed with either the power mode or economy mode selected, operations such as turning the turning body too slow or too fast relative to the operating speed of the work implement A map of the torque limit for the turning speed of the revolving structure, that is, the rotation speed of the motor is prepared for each of the power mode and economy mode, and either map is selected according to the selected work mode setting. By using this, the operation feeling equivalent to that of a conventional excavator is achieved.

However, in the hybrid excavator, since the work machine, the traveling body, and the revolving body are driven by independent drive sources, it is necessary to control both the hydraulic actuator and the electric motor in accordance with switching between the power mode and the economy mode. is there.
For this reason, conventionally, there is known a technique for performing drive control of an electric motor by correcting a torque command value of the electric motor generated by operating the operation lever in accordance with the rotational speed of the electric motor (for example, refer to Patent Document 1). .

JP 2009-133161 A

  However, Patent Document 1 merely corrects the torque command according to the rotational speed of the revolving structure, and does not correct the torque command according to the setting of the power mode or economy mode.

  An object of the present invention is to provide an electric motor control device, an electric motor control method, and a construction machine provided with the electric motor control device that do not cause the operator to feel uncomfortable even in the economy mode.

The control device for the electric motor according to the first invention is:
A control device for an electric motor that controls driving of an electric motor that rotates a revolving body,
A speed command generating means for generating a turning speed command for the swing body based on an operation amount of the operating means of the swing body;
Torque command generating means for generating a torque command for the electric motor based on the speed command generated by the speed command generating means;
A turning speed detecting means for detecting a turning speed of the turning body;
A work mode switching means for switching to any one of a power mode for driving the electric motor with a predetermined torque limit and an economy mode for driving the electric motor with a torque limit lower than the power mode;
Work mode determination means for determining a work mode set by the work mode switching means;
A first map storing means for storing a first map of a torque limit corresponding to the turning speed of the turning body, corresponding to the power mode;
Second map storage means for storing a second map of a torque limit corresponding to the turning speed of the turning body, corresponding to the economy mode;
Based on the work mode determined by the work mode determination means, either the first map stored in the first map storage means or the second map stored in the second map storage means is used. A torque limit generating means for generating a torque limit of the electric motor according to the turning speed command generated by the speed command generating means;
A torque command comparing means for comparing the torque command generated by the torque command generating means with the torque limit generated by the torque limit generating means;
Drive control means for performing drive control of the electric motor at a lower value of the torque command and the torque limit compared by the torque command comparison means,
When the work mode determined by the work mode determination means is an economy mode,
The torque limit generation means is the same as the torque limit of the first map stored in the first map storage means when the turning speed of the turning body detected by the turning speed detection means is equal to or lower than a predetermined speed, or A torque limit larger than the torque limit when the predetermined speed is exceeded is generated.

The control method of the electric motor according to the second invention is as follows:
An electric motor control method for controlling driving of an electric motor for rotating a revolving body,
A procedure for generating a turning speed command for the turning body based on an operation amount of the operating means of the turning body;
A procedure for generating a torque command for the electric motor based on the generated turning speed;
A procedure for setting a work mode to any one of a power mode for driving the electric motor with a predetermined torque limit and an economy mode for driving the electric motor with a torque limit lower than the power mode;
A procedure for determining whether the set work mode is a power mode or an economy mode;
Based on the determination result, the first map of the torque limit corresponding to the turning speed of the revolving structure corresponding to the power mode, and the torque limit corresponding to the turning speed of the revolving structure corresponding to the economy mode. Using one of the second maps to generate a torque limit for the motor in accordance with the generated turning speed command;
The generated torque command for the motor and a procedure for performing drive control of the motor with the lower value of the generated torque limit,
If it is determined that the work mode is economy mode,
When the detected turning speed of the turning body is equal to or lower than a predetermined speed, a torque limit that is the same as the torque limit of the first map or larger than the torque limit when the predetermined speed is exceeded is generated. To do.

  A construction machine according to a third aspect of the present invention is characterized by including a turning body that is turned by an electric motor, and the electric motor control device of the first aspect of the invention.

  According to the motor control device, the control method, and the construction machine of the present invention, when the work mode is determined to be the economy mode, the second map corresponding to the economy mode is used. In the following, the same torque limit as the torque limit of the first map is generated. Therefore, even if the swinging body is swung while the bucket of the work implement is in contact with the ground, the friction resistance between the bucket and the ground acts. However, the operator does not feel uncomfortable during the turning of the turning body.

1 is a perspective view showing a hybrid excavator according to an embodiment of the present invention. The schematic diagram which shows the whole structure of the hybrid hydraulic shovel which concerns on the said embodiment. The block diagram which shows the control apparatus of the electric motor mounted in the hybrid hydraulic shovel which concerns on the said embodiment. The graph showing the 1st map and 2nd map memorize | stored in the memory | storage means of the control apparatus of the electric motor which concerns on the said embodiment. The flowchart which shows the effect | action of the control apparatus of the electric motor which concerns on the said embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[1] Overall Configuration FIG. 1 shows a hybrid excavator 1 according to an embodiment of the present invention. The hybrid excavator 1 includes a vehicle body 2 and a work implement 3.
The vehicle body 2 includes a traveling body 4 and a turning body 5. The traveling body 4 has a pair of traveling devices 4a. Each traveling device 4a has a crawler belt 4b.
Each traveling device 4a causes the hybrid excavator 1 to travel by driving the crawler belt 4b with a right traveling motor and a left traveling motor described later.

The turning body 5 is provided on the traveling body 4 so as to be turnable, and turns when an electric motor described later is driven.
The revolving unit 5 is provided with a cab 6. The revolving body 5 includes a fuel tank 7, a hydraulic oil tank 8, an engine room 9, and a counterweight 10. The fuel tank 7 stores fuel for driving an engine 17 (see FIG. 2) described later. The hydraulic oil tank 8 stores hydraulic oil discharged from a hydraulic pump 18 (see FIG. 2) described later. The engine chamber 9 houses devices such as an engine 17 and a hydraulic pump 18 which will be described later. The counterweight 10 is disposed behind the engine compartment 9.

The work implement 3 is attached to the front center position of the revolving structure 5 and includes a boom 11, an arm 12, a bucket 13, a boom cylinder 14, an arm cylinder 15, and a bucket cylinder 16. A base end portion of the boom 11 is rotatably connected to the swing body 5. Further, the distal end portion of the boom 11 is rotatably connected to the proximal end portion of the arm 12. The tip of the arm 12 is rotatably connected to the bucket 13.
The boom cylinder 14, the arm cylinder 15, and the bucket cylinder 16 are hydraulic cylinders that are driven by hydraulic oil discharged from a hydraulic pump described later. The boom cylinder 14 operates the boom 11. The arm cylinder 15 operates the arm 12. The bucket cylinder 16 operates the bucket 13.
The working machine 3 is driven by operating these cylinders 14, 15, 16.

FIG. 2 shows the overall configuration of the drive system of the hybrid excavator 1.
The hybrid excavator 1 includes an engine 17, a hydraulic pump 18, and a generator 19 as drive sources.
A hydraulic pump 18 and a generator 19 are mechanically coupled to the output shaft of the engine 17, and the hydraulic pump 18 and the generator 19 are driven by driving the engine 17.
The hydraulic drive system includes a control valve 20, the boom cylinder 14, the arm cylinder 15, the bucket cylinder 16, and the travel motor 21 described above, and the hydraulic pump 18 is driven as a hydraulic source.
The electric drive system includes a capacitor 22, an inverter 23, and a swing motor 24, and the generator 19 and the capacitor 22 serve as a power source for the motor 24 to rotate the swing body 5. The capacitor 22 is, for example, an electric double layer capacitor. The capacitor 22 may be a lithium ion battery or a nickel metal hydride battery that functions as a capacitor.
The generator 19 is provided with a resolver (rotation sensor) 25, detects the rotational speed of the swing motor 24, converts it into an electrical signal, and outputs it to a controller provided in the inverter 23.
Although not shown in FIG. 2, the controller provided in the inverter 23 is provided with a temperature sensor, and the controller detects the temperatures of the capacitor 22 and the inverter 23.

These hydraulic drive system and electric drive system are operated by operation levers (working machine lever, travel lever, turning lever) 26 provided in a cab 6 provided in the vehicle body 2.
The operation amount of the operation lever 26 is converted into an electric signal by the lever operation amount detection means 27.
The lever operation amount detection means 27 corresponds to a pressure sensor that detects the operation amount of the turning lever.
The pressure sensor detects the pilot hydraulic pressure generated in response to the operation of the turning lever, and detects the operation amount of the turning lever 26. If the turning lever is an electric lever, the potentiometer serves as the lever operation amount detection means 27.
A fuel adjustment dial 28 and mode switching means 29 are provided in the cab 6.
The fuel adjustment dial 28 is a switch for setting the fuel supply (injection) amount to the engine 17. The setting by the fuel adjustment dial 28 is converted into an electric signal and provided in the engine controller 30 and the inverter 23. Output to the controller.
The engine controller 30 generates a control command based on the set value of the fuel adjustment dial 28 and outputs it as an electric signal to the electronic governor 31 to control the fuel injection amount of the fuel injection pump 32. The fuel injection amount may be controlled by the common rail.

The mode switching means 29 is a part for setting the work mode of the hybrid excavator 1 to the power mode or the economy mode, and is configured as, for example, an operation button or switch provided in the cab 6 or a touch panel.
The setting in the mode switching means 29 is converted into an electrical signal and output to the engine controller 30, the pump controller 33, and a controller provided in the inverter 23.
The pump controller 33 controls the pump controller 33 to control the swash plate angle of the hydraulic pump 18 based on the set value of the mode switching means 29 to control the discharge amount of the hydraulic oil from the hydraulic pump 18. Generate.
By performing such control, the amount of hydraulic oil supplied to each of the hydraulic cylinders 14 to 16 and the traveling motor 21 is adjusted. At the same time, the engine 17 is output controlled in response to a control command from the engine controller 30 based on the set value of the mode switching means 29.
That is, a power mode in which the output torque of the engine 17 and the absorption torque of the hydraulic pump 18 are matched in a region where the rotation and output torque of the engine 17 are relatively high, and a lower engine output torque characteristic than in the power mode. The hybrid excavator 1 is driven in any one of the economy modes in which is set.

[2] Configuration of Electric Motor Control Device 40 FIG. 3 is a block diagram showing the configuration of the electric motor control device 40. The control device 40 is built in the inverter 23 described above.
The control device 40 generates a speed command and a torque limit command based on the input operation lever signal, temperature sensor signal, fuel dial set value signal, resolver signal, and work mode signal, and outputs them to the inverter 23. Thus, the electric motor 24 is controlled.
The control device 40 includes a speed command generating means 41, a speed deviation calculating means 42, a torque command generating means 43, an operation amount torque limit generating means 44, a temperature torque limit generating means 45, a fuel set value torque limit generating means 46, a turning speed. Torque limit generation means 47, work mode torque limit generation means 48, first map 49, second map 50, torque limit maximum value selection means 51, first torque limit minimum value selection means 52, second torque limit minimum value selection means 53 and a torque command comparison means 54.

Hereinafter, unless otherwise specified, the operation lever 26 will be described as an operation lever for performing a turning operation.
The speed command generation unit 41 is a part that generates a speed command for turning the swing body 5 based on the operation signal of the operation lever 26 output from the lever operation amount detection unit 27.
The speed deviation calculating means 42 compares the speed command generated by the speed command generating means 41 with the detected resolver signal based on the resolver signal output from the resolver 25, and determines the operation amount of the operation lever 26. This is the part for calculating the deviation of the actual turning speed of the turning body 5.
The torque command generator 43 is a part that generates a torque command based on the deviation calculated by the speed deviation calculator 42.

The operation amount torque limit generation unit 44 is a part that generates a torque limit based on the operation amount of the operation lever 26 based on the operation signal of the operation lever 26 output from the lever operation amount detection unit 27. A torque limit map corresponding to the operation amount is not shown, but is stored in a memory provided in the control device 40, and the torque limit is generated by referring to this map. The torque limit corresponding to the generated operation amount is output to the first torque limit minimum value selection means 52. Here, the torque limit increases as the operation amount of the operation lever 26 increases. The torque limit map may be a map stored in advance, or may be obtained by storing reference torque limit data and multiplying the data by a coefficient, or by adding / subtracting an offset amount. .
The temperature torque limit generation means 45 is a part that generates a torque limit based on the temperature sensor signals of the inverter 23 and the capacitor 22 from a temperature sensor (not shown) provided in the control device 40. The torque limit is generated with reference to a map in which the torque limit corresponding to the temperature is stored. The torque limit corresponding to the generated temperature is output to the first torque limit minimum value selection means 52. Here, the torque limit decreases as the temperature increases. The torque limit map may be a map stored in advance, or may be obtained by storing reference torque limit data and multiplying the data by a coefficient, or by adding / subtracting an offset amount. .

The fuel set value torque limit generation means 46 is a part that generates a torque limit based on the fuel set value signal (electrical signal) output from the fuel adjustment dial 28, and torque according to the set state of the fuel adjustment dial 28. A torque limit is generated with reference to a map in which the limit is stored. The torque limit relating to the generated fuel set value is output to the torque limit maximum value selection means 51. Here, the torque limit decreases as the set value signal of the fuel dial is smaller, that is, as the signal indicates a smaller fuel injection amount. The torque limit map may be a map stored in advance, or may be obtained by storing reference torque limit data and multiplying the data by a coefficient, or by adding / subtracting an offset amount. .
The turning speed torque limit generation means 47 is a part that generates a torque limit based on the resolver signal output from the resolver 25, and refers to a map in which the torque limit corresponding to the turning speed of the turning body 5 is stored. Generate torque limit. The generated torque limit related to the turning speed is output to the torque limit maximum value selection means 51. The torque limit decreases as the turning speed indicated by the resolver signal increases. The torque limit map may be a map stored in advance, or may be obtained by storing reference torque limit data and multiplying the data by a coefficient, or by adding / subtracting an offset amount. .

The work mode torque limit generation means 48 is a portion that generates a torque limit based on the work mode signal (electric signal) output from the mode switching means 29 and is stored in a memory provided in the control device 40. The torque limit is generated by referring to the first map 49 or the second map 50.
The hybrid excavator 1 has two modes (power mode and economy mode) as operation modes of the work implement. The power mode is a mode in which the work machine is operated by increasing the output of the engine in order to increase work efficiency. On the other hand, the economy mode is a mode in which the output of the engine is suppressed and the fuel consumption of the engine due to the operation of the work machine is reduced.
Specifically, as shown in FIG. 4, the first map 49 is a torque limit (in accordance with the rotational speed of the swing motor (turning speed (horizontal axis)) when the mode switching means 29 is in the power mode (P mode) ( The upper limit value of the turning torque / vertical axis), for example, f (Nm).
On the other hand, the second map 50 is a torque limit (upper limit value of the turning torque / vertical axis) corresponding to the turning speed (horizontal axis) when the mode switching means 29 is in the economy mode (E mode). The second map 50 is set as a torque limit (for example, e (Nm)) smaller than the torque limit of the first map 49, but the same torque as the first map 49 until a predetermined turning speed, for example, Xrpm. The limit is set, for example, linearly decreases from X (rpm) to A (rpm) Note that by reducing the torque limit linearly, a sudden torque limit variation It is possible to prevent the operator from feeling uncomfortable, and the torque limit of the economy mode, for example, e (Nm), becomes greater than A (rpm), and the first map 50 and the first map up to X rpm. The map 49 may be set to the same torque limit, and the torque limit of the second map 50 is the torque limit of the first map 49 until X rpm. Remote it may be a small setting.

The torque limit maximum value selection means 51 compares the torque limit generated by the fuel set value torque limit generation means 46 with the torque limit generated by the turning speed torque limit generation means 47 and determines the larger torque limit. Output to the first torque limit minimum value selection means 52.
The first torque limit minimum value selection means 52 is selected by the torque limit generated by the manipulated variable torque limit generation means 44, the torque limit generated by the temperature torque limit generation means 45, and the torque limit maximum value selection means 51. The torque limit is compared and the smallest torque limit is output to the second torque limit minimum value selection means 53.

The second torque limit minimum value selection means 53 compares the torque limit selected by the first torque limit minimum value selection means 52 with the torque limit generated by the work mode torque limit generation means 48, and calculates the smaller one. The torque limit is output to the torque limit command comparison means 54.
The torque command comparison means 54 compares the torque command generated by the torque command generation means 43 with the torque limit selected by the second torque limit minimum value selection means 53, and if the torque command does not exceed the torque limit. If so, the torque command (current signal) is output to the inverter 23. If the torque command exceeds the torque limit, the torque limit is output to the inverter 23 as a torque command (current signal), and drive control of the electric motor 24 is performed.

[3] Operation and Effect of Embodiment Next, the operation of the control device 40 of the electric motor 24 described above will be described based on the flowchart shown in FIG.
(1) The speed command generation means 41 and the operation amount torque limit generation means 44 read the operation lever signal of the operation lever 26 (step S1), and the speed command generation means 41 generates a speed command and generates an operation amount torque limit. The means 44 generates a torque limit according to the read operation lever signal (step S2).
(2) The temperature torque limit generation means 45 reads the temperature sensor signal (procedure S3), and generates a torque limit corresponding to the sensor temperature (procedure S4).

(3) The fuel set value torque limit generation means 46 reads the set value signal of the fuel adjustment dial 28 (step S5), and generates a torque limit according to the set value of the fuel adjustment dial 28 (step S6).
(4) The turning speed torque limit generation means 47 reads the resolver signal (turning speed signal) of the resolver 25 (step S7), and generates a torque limit corresponding to the turning speed (step S8).
(5) The torque limit maximum value selection means 51 compares the torque limit generated by the fuel set value torque limit generation means 46 with the torque limit generated by the turning speed torque limit generation means 47, and calculates the larger one. A torque limit is selected (step S9).
(6) The first torque limit minimum value selection means 52 is the torque limit generated by the manipulated variable torque limit generation means 44, the torque limit generated by the temperature torque limit generation means 45, and the torque limit maximum value selection means 51. Among the selected torque limits, the smallest torque limit is selected (step S10).

(7) The work mode torque limit generating means 48 reads the work mode signal output from the mode switching means 29 (procedure S11), and determines whether or not the work mode is the economy mode (procedure S12). .
(7) If it is determined that the work mode is the economy mode, the work mode torque limit generation means 48 reads the turning speed signal output from the resolver 25 (step S13), and uses the second map 50 for torque. A limit is generated (step S14).
(8) On the other hand, if it is determined that the work mode is the power mode, the work mode torque limit generation means 48 generates a torque limit using the first map (step S15).

(9) The second torque limit minimum value selection means 53 compares the torque limit selected by the first torque limit minimum value selection means 52 with the torque limit generated by the work mode torque limit generation means 48, and is smaller. One torque limit is selected (step S16).
(10) Finally, the torque command comparison means 54 compares the torque command generated by the torque command generation means 43 with the torque limit selected by the second torque limit minimum value selection means 53, and the torque command is If the torque limit is not exceeded, the torque command (current signal) is output to the inverter 23. If the torque command exceeds the torque limit, the torque limit is output to the inverter 23 as a torque command (current signal), and drive control of the electric motor 24 is performed.

  According to the present embodiment, when the work mode is determined to be the economy mode, the second map 50 corresponding to the economy mode is used. However, when the turning speed of the revolving structure 5 is equal to or lower than the predetermined speed A (rpm). Since the same torque limit as the torque limit of the first map 49 is generated, even if the turning body is turned with the bucket of the work implement being in contact with the ground or the like, the friction resistance between the bucket and the ground acts. The turning speed of the revolving structure 5 can be increased to the same level as the power mode, and the operator does not feel uncomfortable while the revolving structure 5 is turning.

  In addition, a torque limit related to the operation amount of the operation lever, a torque limit related to the temperature of the capacitor 22 and the inverter 23, a torque limit related to the fuel set value, and a torque limit related to the turning speed are set. Since the torque limit is selected, it is possible to reliably prevent the operator from feeling uncomfortable during the operation.

  INDUSTRIAL APPLICABILITY The present invention can be used for a hybrid type hybrid hydraulic excavator in which a revolving body is turned by an electric motor.

  DESCRIPTION OF SYMBOLS 1 ... Hybrid hydraulic excavator, 2 ... Vehicle main body, 3 ... Work machine, 4 ... Traveling body, 4a ... Traveling device, 4b ... Track, 5 ... Swing body, 6 ... Driver's cab, 7 ... Fuel tank, 8 ... Hydraulic oil tank , 9 ... Engine chamber, 10 ... Counterweight, 11 ... Boom, 12 ... Arm, 13 ... Bucket, 14 ... Boom cylinder, 15 ... Arm cylinder, 16 ... Bucket cylinder, 17 ... Engine, 18 ... Hydraulic pump, 19 ... Power generation 20 ... control valve, 21 ... travel motor, 22 ... capacitor, 23 ... inverter, 24 ... electric motor, 25 ... resolver, 26 ... operating lever, 27 ... lever operation amount detecting means, 28 ... fuel adjustment dial, 29 ... mode Switching means, 30 ... engine controller, 31 ... electronic governor, 32 ... fuel injection pump, 33 ... pump controller, 40 ... control device, DESCRIPTION OF SYMBOLS 1 ... Speed command generation means, 42 ... Speed deviation calculation means, 43 ... Torque command generation means, 44 ... Manipulation amount torque limit generation means, 45 ... Temperature torque limit generation means, 46 ... Fuel set value torque limit generation means, 47 ... Turning speed torque limit generating means 48 ... Work mode torque limit generating means 49 ... First map 50 ... Second map 51 ... Torque limit maximum value selecting means 52 ... First torque limit minimum value selecting means 53 ... Second torque limit minimum value selection means, 54... Torque command comparison means

Claims (3)

A control device for an electric motor that controls driving of an electric motor that rotates a revolving body,
A speed command generating means for generating a turning speed command for the swing body based on an operation amount of the operating means of the swing body;
Torque command generating means for generating a torque command for the electric motor based on the speed command generated by the speed command generating means;
A turning speed detecting means for detecting a turning speed of the turning body;
A work mode switching means for switching to any one of a power mode for driving the electric motor with a predetermined torque limit and an economy mode for driving the electric motor with a torque limit lower than the power mode;
Work mode determination means for determining a work mode set by the work mode switching means;
A first map storing means for storing a first map of a torque limit corresponding to the turning speed of the turning body, corresponding to the power mode;
Second map storage means for storing a second map of a torque limit corresponding to the turning speed of the turning body, corresponding to the economy mode;
Based on the work mode determined by the work mode determination means, either the first map stored in the first map storage means or the second map stored in the second map storage means is used. A torque limit generating means for generating a torque limit of the electric motor according to the turning speed command generated by the speed command generating means;
A torque command comparing means for comparing the torque command generated by the torque command generating means with the torque limit generated by the torque limit generating means;
Drive control means for performing drive control of the electric motor at a lower value of the torque command and the torque limit compared by the torque command comparison means,
When the work mode determined by the work mode determination means is an economy mode,
The torque limit generation means is the same as the torque limit of the first map stored in the first map storage means when the turning speed of the turning body detected by the turning speed detection means is equal to or lower than a predetermined speed, or A motor control device that generates a torque limit that is larger than a torque limit when the predetermined speed is exceeded. An electric motor control method for controlling driving of an electric motor for rotating a revolving body,
A procedure for generating a turning speed command for the turning body based on an operation amount of the operating means of the turning body;
A procedure for generating a torque command for the electric motor based on the generated turning speed;
A procedure for setting a work mode to any one of a power mode for driving the electric motor with a predetermined torque limit and an economy mode for driving the electric motor with a torque limit lower than the power mode;
A procedure for determining whether the set work mode is a power mode or an economy mode;
Based on the determination result, the first map of the torque limit corresponding to the turning speed of the revolving structure corresponding to the power mode, and the torque limit corresponding to the turning speed of the revolving structure corresponding to the economy mode. Using one of the second maps to generate a torque limit for the motor in accordance with the generated turning speed command;
The generated torque command for the motor and a procedure for performing drive control of the motor with the lower value of the generated torque limit,
If it is determined that the work mode is economy mode,
When the detected turning speed of the turning body is equal to or lower than a predetermined speed, a torque limit that is the same as the torque limit of the first map or larger than the torque limit when the predetermined speed is exceeded is generated. To control the motor. A revolving structure that revolves with an electric motor;
A construction machine comprising the motor control device according to claim 1.

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