JP4294086B2 - Electric motor control device - Google Patents

Description

  The present invention relates to an electric motor control device that controls an output torque of an electric motor that operates an inertial body based on an operation of an operation end.

  A hydraulic drive device using a hydraulic pump or a hydraulic motor is used as a drive device for operating an inertial body having a large inertial mass such as a construction machine such as a swing operation of a hydraulic excavator and a hydraulic crane and a traveling operation of a wheel loader. Many were adopted. In recent years, an electric drive system using an electric motor with less energy loss is being adopted instead of a hydraulic drive system using a hydraulic drive device with a large energy loss in order to reduce the hydraulic energy with a control valve. The electric drive system has an advantage that when the inertial body is decelerated, the motor is used as a generator, and braking energy for deceleration can be regenerated.

  However, the hydraulic drive method using the conventional hydraulic drive device is operated so that the operability of the operator controlling the operation of the inertial body by operating the operation ends such as the lever and the pedal is adapted to the human sense of operation. In contrast to the design that is easy, the electric drive system using an electric motor cannot realize the operability and operation feeling like the hydraulic drive system, and there is a problem that it is difficult for the operator to operate.

  In other words, in the hydraulic drive system, the opening torque of the bleed-off control throttle and meter-out control throttle of the spool valve is controlled by the operation of the operation end, so that the output torque depends on the operation amount of the operation end and the rotation speed of the hydraulic motor. Controlled, smooth acceleration, deceleration and stop of the inertial body are performed.However, in the case of the electric drive system, if the rotational speed of the motor is controlled, speed control is performed with the output torque as the maximum value. As a result, there is a problem that the deceleration becomes steep, the smooth operability as in the hydraulic drive system cannot be obtained, and the operation feeling of the operator is far from the hydraulic drive system.

  In order to solve these problems, research and development to move the operability and operation feeling when operating an inertial body such as a construction machine with an electric drive system to those of a hydraulic drive system has been promoted. Some means have been proposed for controlling the output torque of the electric motor based on the operation of the operation end so that the pressure is close to that of the hydraulic drive system (for example, see Patent Documents 1-3).

  In the electric drive type turning control device described in Patent Document 1, the maximum acceleration torque (powering torque) is output when the operation amount at the operation end is the maximum or near the maximum, and when the operation amount is zero or near zero. The maximum braking torque (regenerative torque) is output, and a turning speed sensor is provided to smoothly stop the inertial body at the neutral position of the operation end and detect the turning speed of the inertial body as in the hydraulic drive system. Thus, a deviation between a preset turning speed and an actual turning speed is obtained according to the operation amount at the operation end, and an acceleration torque or a braking torque according to the deviation is commanded, and a turning acceleration or deceleration transient The torque control characteristic according to the operation amount of the operator is obtained in the period.

  In the construction machine drive device described in Patent Document 2, the first target torque is calculated based on a predetermined functional relationship with respect to the operation amount of the operation end, and the operation amount of the operation end is determined in advance. Calculating a target speed of the electric motor based on a predetermined functional relationship, calculating a second target torque based on a predetermined functional relationship with respect to a speed deviation between the target speed of the electric motor and the actual speed; Of these first and second target torques, the output torque of the motor is controlled with the target torque having the smaller absolute value as the target value. That is, in Patent Document 2, for example, during an acceleration operation in which the speed deviation between the target speed and the actual speed of the electric motor is large, the first target torque (<first order) calculated based on the operation amount of the operator is used. 2), the second target torque (<first target torque) calculated based on the speed deviation is the target value when the speed of the motor increases and the speed deviation decreases. By doing so, the torque control characteristic according to the operation amount of the operator can be obtained in the transition period of acceleration or the like, similar to that described in Patent Document 1. In Patent Document 2, the allowable maximum torque calculated based on a predetermined functional relationship with respect to the actual speed of the electric motor is set as the third target torque, and the first and second target torques are set as the third target torque. It is also proposed to prevent the overload of the motor by setting the target torque having the smallest absolute value among these target torques including the target torque of the motor as the target torque.

  Further, in the one described in Patent Document 3, an emulation model that simulates the dynamic characteristics of the hydraulic drive device in real time is incorporated in the controller that controls the electric motor, and the control target value is set by the emulation model according to the operation at the operation end. Calculations are made to control the electric motor.

Japanese Patent Laid-Open No. 2001-10783 JP 2003-33063 A JP 2003-333876 A

  The one described in Patent Document 1 can control the electric motor by a simple algorithm that limits the maximum output torque of the electric motor and commands an acceleration torque or a braking torque according to the deviation of the turning speed. In addition, in the hydraulic drive device, the bleed-off control area of the spool valve is controlled by operating the operation end to control the bleed-off opening area and the bleed-off flow rate (= pump flow rate−motor flow rate) as a function. Since the off-pressure and the meter-out pressure are controlled, there is a problem that the operability and operation feeling are different from those of the hydraulic drive system, unlike the control characteristics of the hydraulic drive apparatus.

  Patent Document 2 describes an output of an electric motor using a target torque having a smaller absolute value among a first target torque based on an operation amount and a second target torque based on a speed deviation of the electric motor as a target value. Although it is described that the torque is controlled and the expression is different, basically the torque output based on the speed deviation is performed by limiting the maximum value to the torque that is output with respect to the manipulated variable, and the result is calculated from both The same technique as that described in Patent Document 1 in which the smaller torque is selected. Therefore, what is described in Patent Document 2 is also different from the control characteristics of the hydraulic drive device, and its operability and operation feeling are different from those of the hydraulic drive system.

  On the other hand, what is described in Patent Document 3 can make the operability and operation feeling quite similar to those of the hydraulic drive system, but since it is necessary to calculate an emulation model of a complex algorithm in real time, the control model is There is a problem that complicated and long calculation time is required, and the response time of control becomes long, so that fine control cannot be performed. Another problem is that a very high performance controller is required to incorporate an emulation model of a complex algorithm.

  Accordingly, an object of the present invention is to provide an electric motor control device capable of obtaining the same operability and operation feeling as those of a hydraulic drive system by control based on a simple algorithm.

In order to solve the above-mentioned problems, the present invention provides an operation detection means for controlling the rotational drive of an electric motor that operates an inertial body by at least an operation of an operation end having a variable operation amount, and detecting the operation amount of the operation end. Rotation detection means for detecting the rotation direction and rotation speed of the electric motor, calculation means for calculating a target torque to be borne by the electric motor based on detection values of the operation detection means and the rotation detection means, An electric motor control means for controlling the output torque of the electric motor in the direction and magnitude of the target torque, and the output torque is a motor control device comprising a power running torque as a motor function of the electric motor and a regenerative torque as a generator function; in, to the arithmetic unit, the power torque is Sadamari a characteristic curve as a parameter the absolute value of the rotational speed of the operation end of the operation amount and the electric motor, the steering Increases the absolute value of the operation amount of the edge is large, the operation amount of the operation end be fixed, and employs a configuration that incorporates the algorithms absolute value decreases as increase of the rotational speed of the motor.

  That is, in the calculation means for calculating the target torque, the power running torque increases when the absolute value of the operation amount at the operation end increases, and the absolute value of the rotation speed of the motor increases even when the operation amount at the operation end is constant. By incorporating an algorithm that becomes smaller, the control characteristics similar to the control of the bleed-off pressure in the hydraulic drive system are provided, and the operator can easily control the target operating speed as described below. With the control based on a simple algorithm, the same operability and operation feeling as the hydraulic drive system can be obtained.

In the hydraulic drive apparatus that drives the hydraulic motor 53 with the hydraulic pump 52 by operating the spool valve 51 as shown in FIG. 7, the effective differential pressure between the meter-in pressure P ₁ and the meter-out pressure P ₂ of the hydraulic motor 53 is Hydraulic motor torque. Drive pressure when people meter-pressure P ₁ is high to drive the hydraulic motor 53, when towards the meter-out pressure P ₂ is high the brake pressure for braking the hydraulic motor 53.

As shown in FIG. 8, when the operation amount of the operation end is large, the opening area of the bleed-off control diaphragm 51a of the spool valve 51 of the hydraulic drive apparatus is reduced, the meter pressure P ₁ with bleed-off pressure P ₀ is increased driving pressure of the hydraulic motor 53 is increased higher, the higher the rotational speed of the hydraulic motor 53 is greater at the same operation amount, meter-pressure P ₁ is controlled so that the driving pressure is reduced is low. Therefore, when the rotational speed of the hydraulic motor 53 increases, the driving pressure gradually decreases, and the acceleration of the inertial body is lost at a value commensurate with the driving resistance due to friction of the driving system or pressure loss of the hydraulic piping system or the spool valve 51, and the operator can The operation speed is controlled as follows. Therefore, by incorporating the above algorithm, it is possible to provide the same control characteristics and control of the meter-pressure P ₁ by bleed-off control aperture 51a of such hydraulic drive system.

Incidentally, meter-in control aperture 51b of the spool valve 51 shown in FIG. 7, when operating the other actuator of the same hydraulic pump 52, and for controlling the meter-pressure P ₁ of the hydraulic motor 53, the hydraulic motor 53 is intended for applying a resistance to the driving pressure, the hydraulic drive system to control the driving pressure by controlling the meter-pressure P ₁ by bleed-off control aperture 51a is in the basic control characteristics.

In the calculation means, the regenerative torque is determined by a characteristic curve using the operation amount of the operation end and the absolute value of the rotation speed of the motor as parameters, and increases as the absolute value of the operation amount of the operation end decreases. Even if the operation amount at the end is constant, by incorporating an algorithm that becomes smaller when the absolute value of the rotational speed of the electric motor becomes smaller, it has the same control characteristics as the control of the meter-out pressure of the hydraulic drive system, and It is possible to obtain the same operability and operation feeling as in the hydraulic drive system.

That is, in the hydraulic drive apparatus as shown in FIG. 7, as shown in FIG. 9, the meter-out control throttle 51c of the spool valve 51 starts to open when the operation amount at the operation end becomes a certain value from zero. As the value increases, the opening area increases. Returning to reduce the operation amount in this state, the higher the meter-out pressure P _2, the same operation amount, the meter-out pressure P ₂ when the rotational speed of the hydraulic motor 53 is reduced is controlled to be lower. Therefore, when the operation amount at the operation end is returned from a certain rotational speed of the hydraulic motor 53, the braking pressure is large when the rotational speed is high, and the braking pressure is reduced as the rotational speed is decreased. The inertia body decelerates at a value commensurate with the driving pressure, and the operation speed is controlled by the operator. Therefore, by incorporating the above algorithm, it is possible to provide the same control characteristics and control of the meter-out pressure P ₂ such hydraulic drive system.

In the case where the operation end is variable in both plus and minus directions in addition to the operation amount, and the electric motor is driven to rotate in both plus and minus directions, the operation detecting means is set to plus or minus the operation amount of the operation end. An operation direction is detected , and the powering torque is determined by a characteristic curve using the operation amount of the operation end and the absolute value of the rotation speed of the motor as parameters. Incorporates an algorithm that increases as the value increases, and decreases even when the operation amount of the operation end is constant, and decreases as the absolute value of the rotational speed of the electric motor increases, or further, the regenerative torque is And a characteristic curve with the absolute value of the rotation speed of the electric motor as parameters, and increase as the absolute value of the operation amount at the operation end decreases. Even operation amount of the operation end is constant, embedded algorithms absolute value of the rotational speed of the motor is reduced becomes smaller, to the arithmetic unit, the operation direction of the operation end and the rotation direction of the motor is reverse In this case, by incorporating an algorithm that sets the power running torque to zero and the regenerative torque to a maximum value, only the one that rotates the motor in one direction by operating the pedal as the operation end, such as traveling control of the wheel loader. In addition, it can also be applied to those that rotate the electric motor in both plus and minus directions by operating the lever as the operation end, such as excavator and crane turning control. When the amount is in the neutral range, a neutral brake function for holding the stop is provided, and the operation direction of the operation end is opposite to the rotation direction of the motor. The inertial body is decelerated with a large braking torque and stopped, for example, when the inertial body starts on a slope or when the inertial body is turned upward on a sloping ground, the inertial body descends when the parking brake is released. Can be prevented. When the inertial body stops and the motor itself stops, the motor outputs a driving torque corresponding to the operation amount in the reverse direction of the operation end, and accelerates the inertial body in the reverse rotation direction.

  That is, in the hydraulic drive apparatus as shown in FIG. 7, when the spool valve 51 is neutral, the meter-in control throttle 51b and the meter-out control throttle 51c are fully closed to block the motor port, and the hydraulic motor 53 is in a so-called neutral state. While the inertial body is turned and stopped, the operation end may be operated in the direction opposite to the rotation direction of the hydraulic motor 53 to increase the braking pressure for deceleration. At this time, the hydraulic motor 53 brakes the inertial body at the maximum pressure by a brake valve (not shown), and when the inertial body stops and the hydraulic motor itself also stops, the drive pressure corresponding to the operation amount in the reverse direction of the operation end. Is output to accelerate the inertial body in the reverse rotation direction.

In the case where the operation end is variable in both plus and minus directions in addition to the operation amount, and the electric motor is driven to rotate in both plus and minus directions, the operation detecting means is set to plus or minus the operation amount of the operation end. An operation direction is detected , and the powering torque is determined by a characteristic curve using the operation amount of the operation end and the absolute value of the rotation speed of the motor as parameters. Incorporates an algorithm that increases as the value increases, and decreases even when the operation amount of the operation end is constant, and decreases as the absolute value of the rotational speed of the electric motor increases, or further, the regenerative torque is And a characteristic curve with the absolute value of the rotation speed of the electric motor as parameters, and increase as the absolute value of the operation amount at the operation end decreases. Even operation amount of the operation end is constant, embedded algorithms absolute value of the rotational speed is reduced becomes smaller the motor, the arithmetic means, when the operation amount of the operation end of the neutral range including zero, or When the operating direction of the operating end and the rotating direction of the electric motor are opposite to each other, the absolute value of the regenerative torque is set to the absolute value of the rotating speed of the electric motor within a small range where the absolute value of the rotating speed of the electric motor is near zero. Incorporating an algorithm that increases the value according to the value and decreases the absolute value of the regenerative torque when the absolute value of the rotational speed decreases, thereby starting the inertial body on a slope or turning the inertial body upward on a slope. Sometimes, the inertial body can be prevented from descending and retreating or turning downward and smoothly starting on a slope or turning upward.

  That is, on slopes and slopes, internal torque of the hydraulic motor occurs due to load torque applied to the hydraulic motor, and so-called slip rotation occurs. This slip rotation is a minute value, and the rotation speed increases according to the pressure of the hydraulic motor. For this reason, when the inertial body starts on a slope or turns upward in the hydraulic drive system, the load check shown in FIG. 7 is performed when the hydraulic motor torque due to the drive pressure of the hydraulic motor is smaller than the load torque due to the inclination. When the reverse rotation of the hydraulic motor in the descending direction is suppressed by the valve 51d and the hydraulic motor torque due to the driving pressure becomes larger than the load torque due to the inclination, the start of the slope and the upward turning are started smoothly.

  On the other hand, in the conventional electric drive system, as shown in FIG. 10, when the output torque of the motor is smaller than the load torque due to the inclination, if the motor reverses in the descending direction even a little, it will be in the regenerative state with the maximum torque. When the output torque becomes larger than the load torque, a power running state is established. For this reason, the movement of the motor when the absolute value of the rotational speed is near zero becomes vibrational, and it is not possible to smoothly start the slope or turn upward. Therefore, as shown in FIG. 6 later, an algorithm for increasing the absolute value of the regenerative torque in accordance with the magnitude of the absolute value of the rotational speed of the motor is incorporated in a range where the absolute value of the rotational speed of the motor is small near zero. Thus, when the output torque becomes larger than the load torque, the electric motor is switched from regenerative to power running, and the hill can start smoothly and turn upward as in the hydraulic drive system.

The calculating means divides the target torque into a driving torque for driving the inertial body by the electric motor and a driven torque for driving the electric motor by the inertial body by a pre-stored calculation algorithm, and these driving torques The absolute value of the drive torque is determined by a characteristic curve having the operation amount of the operation end and the absolute value of the rotation speed of the motor as parameters in the calculation algorithm, A driving torque calculation algorithm that increases as the absolute value of the operating amount at the operating end increases, and decreases as the absolute value of the rotational speed of the motor increases even when the operating amount at the operating end is constant, and the driven torque absolute value, Sadamari the absolute value of the rotational speed of the electric motor and the operation amount of the operation end by the characteristic curve as a parameter, an operation of the operation end At least the drive torque calculation algorithm is selected from among the driven torque calculation algorithms that become larger when the absolute value of the motor becomes smaller and becomes smaller when the absolute value of the rotational speed of the electric motor becomes smaller even when the operation amount at the operation end is constant. As a result, the control design of the output torque of the electric motor can be performed in the same manner as in the case of controlling the hydraulic motor torque by the control throttle of the control valve. Therefore, the design and adjustment of the motor torque characteristics can be easily performed based on the conventional knowledge. That is, the hydraulic motor torque is controlled by the effective differential pressure between the meter-in pressure by the bleed-off control throttle and the meter-out pressure by the meter-out control throttle, but the bleed-off control throttle and the meter-out control throttle have independent characteristics. It is possible to design, and the control characteristic of the motor torque is determined as the sum of both characteristics (difference in calculating the pressure). In the case of motor output torque control, both characteristics can be achieved by designing the drive torque against the meter-in pressure from the bleed-off control throttle of the hydraulic motor and the driven torque against the meter-out pressure from the meter-out control throttle. The target torque can be designed as the sum of

  An algorithm for reducing the absolute value of the drive torque by adding a calculation of a resistance torque that reduces the target torque to the calculation algorithm, and the absolute value of the resistance torque increases as the absolute value of the rotational speed of the motor increases, and By incorporating one or both of the algorithms for increasing the absolute value of the driven torque, in addition to the resistance of the mechanical drive system, a resistance torque element corresponding to the pressure loss in the hydraulic drive system is added to the control system. The point at which the actual output torque and load torque of the electric motor are balanced is further stabilized, and the control can be stably performed so that the target speed intended by the operator is achieved. In addition, although the pressure loss in a hydraulic drive system becomes an energy loss, since this resistance torque is virtual, it does not become an energy loss.

  That is, in the hydraulic drive apparatus as shown in FIG. 7, there is a pressure loss of the piping system from the hydraulic pump 52 to the hydraulic motor 53, and a pressure loss due to the meter-in control throttle 51b and the meter-out control throttle 51c of the spool valve 51. These pressure losses increase in proportion to the square of the flow rate when the flow rate of the discharge oil from the hydraulic pump 52 increases, and the output torque and load torque of the hydraulic motor 53 are balanced by the presence of these pressure losses. The point to be stabilized is stable, and the operator can easily control the target speed.

  The inertial body that operates in each electric motor described above can be an inertial body that performs a turning operation or a traveling operation of the construction machine.

  In the motor control device of the present invention, the power running torque increases as the absolute value of the operation amount at the operation end increases in the calculation means for calculating the target torque, and even if the operation amount at the operation end is constant, By incorporating an algorithm that decreases as the absolute value of the rotational speed increases, it has the same control characteristics as the bleed-off pressure control in the hydraulic drive system, making it easier for the operator to control the target operating speed. With the control based on a simple algorithm, the same operability and operation feeling as the hydraulic drive system can be obtained.

  The calculation means incorporates an algorithm in which the regenerative torque increases when the absolute value of the operation amount at the operating end decreases, and decreases when the absolute value of the rotation speed of the motor decreases even when the operating amount at the operating end is constant. Thus, it is possible to provide the same control characteristics as the meter-out pressure control of the hydraulic drive system, and to obtain the same operability and operation feeling as those of the hydraulic drive system.

  In the case where the operation end is variable in both plus and minus directions in addition to the operation amount and the motor is driven to rotate in both plus and minus directions, the operation detection means is configured to change the operation amount at the operation end and the plus or minus operation direction. When the operation amount at the operating end is in a neutral range including zero, or when the operating direction of the operating end is opposite to the rotation direction of the motor, the computing means is set to zero and the regenerative torque By incorporating an algorithm that maximizes the value of the wheel loader, not only the one that rotates the motor in one direction by the operation of the pedal as the operation end, such as the traveling control of the wheel loader, but also the turning control of the excavator or crane, It can also be applied to the one that rotates the electric motor in both plus and minus directions by operating the lever as the operation end. When the work is in the neutral range, a neutral brake function for holding the stop is provided, and when the operation direction of the operation end is opposite to the rotation direction of the motor, the inertial body is decelerated with a large braking torque. For example, when the inertial body is started on a slope or when the inertial body is turned upward on an inclined ground, the inertial body can be prevented from descending when the parking brake is released.

  In the case where the operation end is variable in both plus and minus directions in addition to the operation amount and the motor is driven to rotate in both plus and minus directions, the operation detection means is configured to change the operation amount at the operation end and the plus or minus operation direction. The absolute value of the rotation speed of the motor is detected when the operation amount of the operation end is in a neutral range including zero, or when the operation direction of the operation end is opposite to the rotation direction of the motor. By incorporating an algorithm that increases the absolute value of the regenerative torque according to the absolute value of the rotational speed of the motor in a small range near zero, the inertial body starts on a slope, or the inertial body turns upward on a sloping ground. In this case, the inertial body can be prevented from descending and retreating and turning downward, and can smoothly start on a slope and turn upward.

  The calculation means divides the target torque into a driving torque for driving the inertial body by the electric motor and a driven torque for driving the electric motor by the inertial body by a pre-stored calculation algorithm, and these driving torque and driven The absolute value of the drive torque increases as the absolute value of the operation amount at the operating end increases, and even if the operating amount at the operating end is constant, The driving torque calculation algorithm that decreases as the absolute value of the speed increases, and the absolute value of the driven torque increases as the absolute value of the operating amount at the operating end decreases, and even if the operating amount at the operating end is constant, the motor At least the driving torque calculation algorithm is incorporated among the driven torque calculation algorithms that become smaller when the absolute value of the rotation speed of the motor becomes smaller Therefore, the control design of the output torque of the motor can be performed in the same way as in the case of controlling the hydraulic motor torque by the control throttle of the control valve, and different torque control characteristics are provided for the power running and regeneration of the motor. Thus, the inertial body can be operated, and, similarly to the hydraulic drive system, the change of the electric motor from acceleration to deceleration and the change from deceleration to acceleration can be performed continuously and smoothly.

  An algorithm for reducing the absolute value of the drive torque by adding a calculation of a resistance torque that reduces the target torque to the calculation algorithm, and the absolute value of the resistance torque increases as the absolute value of the rotational speed of the motor increases, and a driven torque By incorporating one or both of the algorithms to increase the absolute value of the motor, in addition to the resistance of the mechanical drive system, a resistance torque element corresponding to the pressure loss in the hydraulic drive system is added to the control system. The balance between the output torque and the load torque is more stable, and the control can be stably performed so that the target speed intended by the operator is obtained.

The side view which shows the hydraulic excavator incorporating the control apparatus of the electric motor which concerns on this invention The block diagram which shows the structure of the control apparatus of the electric motor integrated in the hydraulic shovel of FIG. Graph showing the basic map of the algorithm of FIG. FIG. 3 is a graph showing the target torque in the first quadrant and the fourth quadrant of the graph of FIG. 3 broken down into drive torque and driven torque. The graph which shows the resistance torque calculated with the calculation algorithm of FIG. FIG. 2 is a graph showing a driven torque calculated in a small range where the absolute value of the rotation speed is near zero by the calculation algorithm of FIG. Piping system diagram of conventional hydraulic drive The graph which shows the control characteristic of the bleed-off pressure in the hydraulic drive unit of FIG. The graph which shows the control characteristic of the meter out pressure in the hydraulic drive unit of FIG. Graph showing the control characteristics when the absolute value of the rotational speed in the conventional electric drive system is near zero

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric motor 1a Rotation detection means 2 Operation lever 2a Operation detection means 3 Controller 3a Memory 3b Arithmetic algorithm 4 Inverter 4a Signal conversion circuit 4b Current control circuit 20 Traveling body 21 Traveling hydraulic motor 22 Reduction gear 30 Revolving body 31 Engine 32 Hydraulic pump 33 Power generation Machine 34 power storage device 35 reduction gear 36 converter 40 excavation attachment 41 boom 41a boom cylinder 42 arm 42a arm cylinder 43 bucket 43a bucket cylinder

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a hydraulic excavator incorporating an electric motor control device according to the present invention. The hydraulic excavator includes a crawler type lower traveling body 20, an upper revolving body 30 as an inertial body that swings left and right on the lower traveling body 20, and an excavation attachment 40 attached to a front portion of the revolving body 30. It consists of. The lower traveling body 20 travels by the left and right crawlers 23 being individually driven by the traveling hydraulic motor 21 and the speed reducer 22. The excavation attachment 40 includes a boom 41, an arm 42, and a bucket 43, and a boom cylinder 41a, an arm cylinder 42a, and a bucket cylinder 43a for operating them.

  The revolving body 30 is equipped with an engine 31, a hydraulic pump 32 and a generator 33 driven by the engine 31, a power storage device 34 such as a battery and a capacitor, and an electric motor 1 and a speed reducer 35 that rotate the revolving body 30. Has been. The oil discharged from the hydraulic pump 32 is supplied to the traveling hydraulic motor 21, the boom 41, the arm 42, and the cylinders 41 a, 43 a of the bucket 43 via control valves. The electric power of the generator 33 is stored in the power storage device 34 with the voltage and current controlled by the converter 36 and supplied to the electric motor 1 via the inverter 4 described later. The electric motor 1 is a permanent magnet type motor having a permanent magnet as a rotor, and the electric motor control device according to the present invention controls the electric motor 1 to rotate the revolving body 30.

  FIG. 2 is a block diagram showing the configuration of the control device of the electric motor 1. This control device includes an operation detection means 2a for detecting an operation amount X in both plus and minus directions of an operation lever 2 as an operation end, and a rotation detection means 1a for detecting a plus / minus rotation speed N of the electric motor 1 rotating in both directions. From the detected operation amount X of the operating lever 2 and the rotational speed N of the electric motor 1, the controller 3 as arithmetic means for calculating the direction and magnitude of the target torque To which the electric motor 1 should bear, and the generator 33 Alternatively, the electric power supplied from the power storage device 34 includes an inverter 4 as electric motor control means for controlling the output torque T of the electric motor 1 to the direction and magnitude of the target torque To calculated by the controller 3. .

  The controller 3 is provided with a memory 3a, and an arithmetic algorithm 3b for dividing the target torque To into the drive torque Ta and the driven torque Tb to express the control characteristics of the hydraulic drive system is previously stored in the memory 3a. It is remembered. The target torque To is calculated as the sum of the driving torque Ta and the driven torque Tb. When the calculated target torque To is output in the same direction as the operation direction of the operation lever 2, it becomes a power running torque, and the operation direction If the output is in the opposite direction, the regenerative torque is generated. The inverter 4 includes a signal conversion circuit 4a and a current control circuit 4b. The signal conversion circuit 4a converts the target torque To input from the controller 3 into a target current Io, and the current control circuit 4b outputs to the motor 1. Feedback control is performed so that the current I becomes the target current Io.

  FIG. 3 shows a basic map for calculating the target torque To by the calculation algorithm 3b. In this basic map, the horizontal axis is the plus / minus operation amount X of the control lever 2, the vertical axis is the target torque To, and these relationships are represented by a characteristic curve with the plus / minus rotational speed N of the motor 1 as a parameter. In the first quadrant and the third quadrant in which the operation amount X and the target torque To have the same sign, the target torque To is the power running torque, and the second quadrant and the second quadrant in which the operation amount X and the target torque To have different signs. In the four quadrants, the target torque To is the regenerative torque. That is, in the first quadrant, the right turning power running, in the second quadrant, the left turning regeneration, in the third quadrant, the left turning power running, and in the fourth quadrant, the right turning regeneration. In the graph of FIG. 3, in order to make the map easy to see, each characteristic curve is displayed only when the parameter rotation speed N = 0, 1/2, 1 (maximum speed).

  In the first quadrant and the third quadrant of the basic map, the absolute value of the target torque To, which is the power running torque, increases as the absolute value of the operation amount X of the operation lever 2 increases, and even if the operation amount X is constant. When the absolute value of the rotational speed N of the electric motor 1 is increased, the calculation is performed so that the absolute value of the rotational speed N decreases, and the same control characteristics as the control of the bleed-off pressure in the hydraulic drive system are obtained. Further, in the second quadrant and the fourth quadrant of the basic map, the absolute value of the target torque To that is the regenerative torque increases as the absolute value of the manipulated variable X decreases, and even if the manipulated variable X is constant, the rotational speed When the absolute value of N is decreased, the calculation is performed so as to decrease, and control characteristics similar to those of the meter-out pressure control in the hydraulic drive system can be obtained.

Further, in the basic map shown in FIG. 3, the power running torque is zero and the regenerative torque when the operation amount X is in a neutral range including zero and when the operation direction of the operation lever 2 and the rotation direction of the motor 1 are opposite. Is set to the maximum value Tmax. Therefore, for example, when the rotational speed N = ½ (Q ₁ point) in the fourth quadrant, the operation amount X of the operation lever 2 is changed from X ₁ to −X ₂ as indicated by an arrow in the figure. When the motor 1 is operated in the direction opposite to the rotational direction, the regenerative torque is output at Tmax until the rotational speed N becomes zero, the right turn is decelerated, and when the rotational speed N becomes zero, the third quadrant A power running torque corresponding to the rotational speed N = 0 (Q ₂ point) when the operation amount X is set to −X ₂ is output, and acceleration is started so as to turn the revolving body 30 to the left. In this embodiment, the absolute value of the power running torque is also set to the same maximum value Tmax as the regenerative torque.

  FIG. 4 shows the first and fourth quadrants that turn right in FIG. 3 by disassembling the target torque To into a drive torque Ta indicated by a solid line and a driven torque Tb indicated by a dotted line. . The driving torque Ta corresponds to the torque due to the meter-in pressure of the hydraulic motor, and the driven torque Tb corresponds to the torque due to the meter-out pressure of the hydraulic motor. The absolute value of the driving torque Ta in the first quadrant is calculated so as to increase as the absolute value of the operation amount X increases, and to decrease as the absolute value of the rotational speed N increases even if the operation amount X is constant, The maximum value Tamax is set. In addition, the absolute value of the driven torque Tb in the fourth quadrant increases as the absolute value of the operation amount X decreases, and decreases as the absolute value of the rotational speed N decreases even if the operation amount X is constant. The maximum value Tbmax is set in the neutral range in which the operation amount X is calculated to be zero and in the third quadrant where the operation direction of the operation lever 2 and the rotation direction of the electric motor 1 are opposite to each other. The target torque To shown in the first quadrant and the fourth quadrant of FIG. 3 is obtained as the sum of the drive torque Ta and the driven torque Tb calculated in this way. Although illustration is omitted, the target torque To in the second quadrant and the third quadrant of FIG. 3 that turns left is also obtained as the sum of the drive torque Ta and the driven torque Tb calculated in the same manner.

  The graph of FIG. 5 shows the resistance torque ΔT that reduces the target torque To calculated by the calculation algorithm 3b. The resistance torque ΔT increases as the absolute value of the rotational speed N of the electric motor 1 increases, and the second quadrant reduces the absolute value of the calculated drive torque Ta in the first and third quadrants. And the fourth quadrant are added so as to increase the absolute value of the calculated driven torque Tb, and stabilize the point where the actual output torque and load torque are balanced, such as pressure loss in the hydraulic drive system. , So that the operator can stably control the target speed as intended. The absolute value of the resistance torque ΔT increases in proportion to the primary to secondary order with respect to the absolute value of the rotational speed N of the electric motor 1.

  The graph of FIG. 6 is calculated by the calculation algorithm 3b when the operation amount X of the operation lever 2 is in the neutral range, or when the operation direction of the operation lever 2 and the rotation direction of the electric motor 1 are opposite directions. The driven torque Tb in a small range where the absolute value of the rotational speed N of the electric motor 1 is near zero is shown. This driven torque Tb is calculated so as to increase in accordance with the magnitude of the absolute value of the rotational speed N in a small range where the absolute value of the rotational speed N is near zero, and when the revolving body 30 is turned upward on an inclined ground In addition, when the drive torque Ta is smaller than the load torque due to the inclination, the reverse rotation of the electric motor 1 in the descending direction is suppressed. If the driving torque Ta becomes larger than the load torque, the revolving body 30 starts to turn upward smoothly by the driving torque Ta. In the case of this figure, it turns right.

  In the above-described embodiment, the generator and the power storage device are used as power sources to control the electric motor that swings the upper swing body of the excavator left and right. However, the motor control device according to the present invention includes, for example, a wheel The present invention can also be applied to a motor that controls an electric motor that moves an inertial body in only one direction, such as a loader that travels. Also, the power source of the motor is not limited to the generator or the power storage device. For example, when controlling the motor that operates the inertial body of the device placed in a factory or the like, the power supplied from the power company or the like Can be used as a power source.

  Furthermore, in the above-described embodiment, the calculation algorithm of the driving torque and the driven torque is stored in the controller as a characteristic curve expressed by a map. However, the calculation algorithm of the driving torque and the driven torque is determined by the operation of the operation end. You may make it memorize | store as numerical formula which uses quantity and the rotational speed of an electric motor as a parameter.

Claims (7)

Rotation driving of an electric motor that operates an inertial body is controlled by operation of an operation end that can change at least an operation amount, operation detection means that detects an operation amount of the operation end, and a rotation direction and a rotation speed of the electric motor are detected. Rotation detection means, calculation means for calculating a target torque to be borne by the electric motor based on detection values of the operation detection means and the rotation detection means, and output torque of the electric motor in the direction and magnitude of the target torque. An electric motor control means for controlling the motor, wherein the output torque comprises a power running torque as a motor function of the motor and a regenerative torque as a generator function. Sadamari operation amount of the operation end and the absolute value of the rotational speed of the motor in the characteristic curve of a parameter, the magnitude if the absolute value of the operating amount of the operation end is larger It will, be an operation amount of the operation end is constant, the control unit for an electric motor, wherein the incorporating and algorithms absolute value decreases as increase of the rotational speed of the motor. In the calculation means, the regenerative torque is determined by a characteristic curve using the operation amount of the operation end and the absolute value of the rotation speed of the motor as parameters, and increases as the absolute value of the operation amount of the operation end decreases. The motor control device according to claim 1, wherein an algorithm that incorporates an algorithm that becomes smaller when the absolute value of the rotational speed of the motor becomes smaller even if the end operation amount is constant is incorporated. Rotation driving of an electric motor that operates an inertial body is controlled by operation of an operation end that can change at least an operation amount, operation detection means that detects an operation amount of the operation end, and a rotation direction and a rotation speed of the electric motor are detected. Rotation detection means, calculation means for calculating a target torque to be borne by the electric motor based on detection values of the operation detection means and the rotation detection means, and output torque of the electric motor in the direction and magnitude of the target torque. An electric motor control means for controlling the motor, wherein the output torque comprises a power running torque as a motor function of the motor and a regenerative torque as a generator function. Is variable in both plus and minus directions, and the electric motor is rotationally driven in both plus and minus directions, and the operation detecting means is operated at the operation end. And detects the positive and negative operating direction, to the arithmetic unit, the power running torque, Sadamari the absolute value of the rotational speed of the electric motor and the operation amount of the operation end by the characteristic curve as a parameter, the operating end Incorporate an algorithm that increases as the absolute value of the operation amount increases and decreases even when the operation amount at the operation end is constant, or further decreases the regenerative torque. The operating amount of the operating end and the absolute value of the rotation speed of the motor are determined by a characteristic curve, and the absolute value of the operating amount of the operating end increases and the operating amount of the operating end is constant. also, the embedded algorithms absolute value of the rotational speed of the motor is reduced becomes smaller, to the arithmetic unit, the rotation direction of the motor and the operation direction of the operation end There when reverse, zero the power torque, a motor control apparatus, characterized in that incorporates an algorithm with a maximum value of the regenerative torque. Rotation driving of an electric motor that operates an inertial body is controlled by operation of an operation end that can change at least an operation amount, operation detection means that detects an operation amount of the operation end, and a rotation direction and a rotation speed of the electric motor are detected. Rotation detection means, calculation means for calculating a target torque to be borne by the electric motor based on detection values of the operation detection means and the rotation detection means, and output torque of the electric motor in the direction and magnitude of the target torque. An electric motor control means for controlling the motor, wherein the output torque comprises a power running torque as a motor function of the motor and a regenerative torque as a generator function. Is variable in both plus and minus directions, and the electric motor is rotationally driven in both plus and minus directions, and the operation detecting means is operated at the operation end. And detects the positive and negative operating direction, to the arithmetic unit, the power running torque, Sadamari the absolute value of the rotational speed of the electric motor and the operation amount of the operation end by the characteristic curve as a parameter, the operating end Incorporate an algorithm that increases as the absolute value of the operation amount increases and decreases even when the operation amount at the operation end is constant, or further decreases the regenerative torque. The operating amount of the operating end and the absolute value of the rotation speed of the motor are determined by a characteristic curve, and the absolute value of the operating amount of the operating end increases and the operating amount of the operating end is constant. also, the embedded algorithms absolute value of the rotational speed is reduced becomes smaller the motor, the arithmetic unit, the operation amount of the operation end time of the neutral range including zero Alternatively, when the operating direction of the operating end and the rotating direction of the electric motor are opposite to each other, the absolute value of the regenerative torque is set to the rotational speed of the electric motor within a small range where the absolute value of the rotating speed of the electric motor is near zero. An electric motor control device incorporating an algorithm for increasing the absolute value according to the magnitude of the absolute value and decreasing the absolute value of the regenerative torque when the absolute value of the rotational speed decreases. The calculation means divides the target torque into a drive torque for driving the inertial body by the electric motor and a driven torque for driving the electric motor by the inertial body according to a calculation algorithm stored in advance, and these drive torques The absolute value of the drive torque is determined by a characteristic curve having the operation amount of the operation end and the absolute value of the rotation speed of the motor as parameters in the calculation algorithm, A driving torque calculation algorithm that increases as the absolute value of the operating amount at the operating end increases, and decreases as the absolute value of the rotational speed of the motor increases even when the operating amount at the operating end is constant, and the driven torque absolute value, Sadamari the absolute value of the rotational speed of the electric motor and the operation amount of the operation end by the characteristic curve as a parameter, an operation of the operation end At least the drive torque calculation algorithm is selected from among the driven torque calculation algorithms that become larger when the absolute value of the motor becomes smaller and becomes smaller when the absolute value of the rotational speed of the electric motor becomes smaller even when the operation amount at the operation end is constant. The motor control device according to any one of claims 1 to 4, wherein the motor control device is incorporated.   An algorithm for reducing the absolute value of the drive torque by adding a calculation of a resistance torque that reduces the target torque to the calculation algorithm, and the absolute value of the resistance torque increases as the absolute value of the rotational speed of the motor increases, and The motor control device according to claim 5, wherein either or both of algorithms for increasing the absolute value of the driven torque are incorporated.   The motor control device according to any one of claims 1 to 6, wherein the inertial body that operates by the motor is an inertial body that performs a turning operation or a traveling operation of a construction machine.

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