JP7092620B2 - Power conversion system and motor control method - Google Patents

Description

The present invention relates to a power conversion system and a motor control method.

As a prior art, for example, in Patent Document 1, in a power supply device and a power supply system that include a power supply circuit, a power supply control circuit, and a power storage device and supply power to a device having a function of storing energy, the device is stored in the device. A power supply device and a power supply system that variably set a control command value of a power storage device based on the energy generated are disclosed.

Japanese Unexamined Patent Publication No. 2011-200048

In the above-mentioned prior art, low cost, low loss and high density are achieved by variably setting and controlling the control command value of the storage device based on the rotational energy or spring energy stored in the inertial load such as the motor and the motor load. The purpose is to provide a powerful power supply.

Generally, the characteristics of motors and storage devices change due to deterioration over time. High-precision control is required in response to changes in characteristics due to these various factors.

The present invention has been made in view of the above requirements.

The present application includes a plurality of means for solving the above problems, and to give an example thereof, a power conversion system including a power conversion device for supplying power to a motor and a power supply device for supplying power to the power conversion device. The power conversion device includes a power conversion unit that converts power, a control unit that controls the power conversion unit, and a current detection unit that detects a current in the power conversion unit. , A storage device that stores power according to the voltage, a buck-boost power supply circuit that changes the voltage of the storage device based on a voltage command, and the buck-boost as the voltage command by calculating the energy stored in the storage device. It has an arithmetic circuit that outputs to a power supply circuit, and the control unit calculates the power running energy or regenerative energy of the motor using the information from the encoder included in the motor and the current value detected by the current detection unit. Then, the calculation circuit calculates the energy to be stored in the storage device based on the power running energy or the regenerative energy of the motor calculated by the control unit.

According to the present invention, it is possible to suppress a deviation in control due to a change in characteristics due to deterioration of the motor load over time, and it is possible to suppress deterioration in control accuracy. Further, it is possible to suppress excessive storage of electric power in the storage device, reduce power loss, and realize miniaturization of the storage device.

It is a figure which shows typically the whole structure of the power conversion system which concerns on this invention. It is a figure explaining the rotational or kinetic energy stored in the inertial load. It is a figure which schematically explains the structure of the press machine with a pneumatic die cushion. It is a figure explaining the energy stored in the pneumatic die cushion. It is a figure explaining the energy stored in the elevating device. It is a figure explaining the relationship between the crank shaft angular velocity and the slide velocity of a crank press machine. It is a figure which shows an example of the electric power conversion system which concerns on 1st Embodiment schematically. It is a figure which shows an example of the details of a forward converter of a power supply device, a buck-boost power supply circuit, and a storage device, and shows the case where a circuit which performs a boost operation is used as a buck-boost power supply circuit. It is a figure which shows the other example of the details of a forward converter of a power supply device, a buck-boost power supply circuit, and a storage device, and shows the case where a circuit which performs a step-down operation is used as a buck-boost power supply circuit. It is a figure which shows the details of the inverse converter of a motor power converter, and the position speed current control circuit. It is a figure which shows an example of the waveform of the angular velocity detection signal of a slide motor at the time of drawing with a press machine with a pneumatic die cushion. It is a figure which shows an example of the waveform of the torque detection signal of a slide motor at the time of drawing with a press machine with a pneumatic die cushion. It is a figure which shows an example of the output waveform of the acceleration / deceleration torque calculation circuit when drawing is performed by the press machine with a pneumatic die cushion. It is a figure which shows an example of the output waveform of the addition / subtraction arithmetic unit at the time of drawing processing by the press machine with a pneumatic die cushion. It is a figure which shows an example of the output waveform of the inertial load storage energy calculation circuit at the time of drawing with a press machine with a pneumatic die cushion. It is a figure which shows an example of the output waveform of the elastic load storage energy calculation circuit at the time of drawing processing by the press machine with a pneumatic die cushion. It is a figure which shows an example of the output waveform of the addition arithmetic unit of the storage energy calculation circuit at the time of drawing processing by the press machine with a pneumatic die cushion. It is a figure which shows an example of the output waveform of the voltage command calculation circuit at the time of drawing processing by the press machine with a pneumatic die cushion. It is a figure which shows an example of the electric power conversion system which concerns on 2nd Embodiment schematically. It is a figure which shows an example of the electric power conversion system which concerns on 3rd Embodiment schematically. It is a figure which schematically explains the structure of the press machine with a servo die cushion which concerns on 3rd Embodiment. It is a figure which shows an example of the electric power conversion system which concerns on 4th Embodiment schematically. It is a figure which shows typically an example of the electric power conversion system which concerns on 5th Embodiment. It is a figure which shows an example of the electric power conversion system which concerns on 6th Embodiment schematically.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, the basic principle of the power conversion system according to the present embodiment will be described.

FIG. 1 is a diagram schematically showing an overall configuration of a power conversion system according to the present embodiment.

The power conversion system of the present embodiment controls the operation of the motor 3 by converting the power supplied from the power supply 11 to the motor 3, and is a power supply device 1 and a motor power conversion device 2 (power conversion device). ) And is roughly configured. The power supply device 1 is a buck-boost power supply circuit that controls a forward converter 4 that converts the power supplied from the power supply 11 as an AC voltage into a DC voltage GBP and a voltage GBP of the power converted into a DC voltage by the forward converter 4. 5 and the voltage-controlled power of the buck-boost power supply circuit 5 are stored and supplied to the motor power conversion device 2, and the power generated by the regenerative operation of the motor 3 and supplied via the motor power conversion device 2 is supplied. It includes a storage device 6 (for example, a capacitor, a storage battery, etc.) for storing, and a voltage command calculation circuit 15 that controls the operation of the buck-boost power supply circuit 5 to control the voltage GBP. Further, the motor power conversion device 2 controls the operation of the motor 3 by converting the power supplied from the buck-boost power supply circuit 5 of the power supply device 1 via the storage device 6 and supplying it to the motor 3. The reverse converter (inverter) 7 (power conversion unit) that supplies the power generated by the regenerative operation of 3 to the storage device 6 of the power supply device 1 and the reverse converter 7 are controlled and provided in the motor 3. The angular speed of the motor 3 obtained through the inverter 10 and the torque of the motor 3 calculated based on the current value detected by the current detector (current detector) provided in the motor 3 are set in advance. A control circuit 8 (control unit) that calculates the stored energy, which is the energy stored in the motor 3 and the motor load 120 driven by the motor 3, based on the moment related to the motor 3, and the storage calculated by the control circuit 8. The buck-boost power supply circuit 5 is controlled based on the energy and the maximum power amount predetermined as the maximum value of the amount of power that can be stored in the storage device 6, and the power stored in the storage device 6 from the power supply 11 is controlled. It is provided with a voltage command calculation circuit 15 for controlling the amount. Here, the buck-boost power supply circuit 5 and the voltage command calculation circuit 15 constitute a power storage device control circuit that controls the amount of power stored in the storage device 6 from the power supply 11 based on the stored energy and the maximum power amount. There is.

At this time, considering a rotary drive type motor 3 composed of an AC motor 9 and an encoder 10, the output shaft of the motor 3 rotates, and the rotational energy thereof is stored on the load side (motor load 120) including the motor shaft. Be done. Further, considering a motor 3 such as a linear motor, a movable portion loaded with a load moves on a straight line, and kinetic energy is stored in the load side and the movable portion (motor load 120).

Except for loads where the rotation angle of the motor 3 moves only at a minute angle (for example, 10 ° or less) and special loads where the rotation angle of the motor 3 moves only at a minute distance (10 mm or less) on a straight line, electronic parts assembly machines and semiconductor / liquid crystal manufacturing equipment. In general industrial machines such as metal machine machines, metal processing machines, conveyor machines and industrial robots, when an object on the load side moves, rotation or kinetic energy is accumulated in the object.

Assuming that the moment of inertia of the rotating object is J and the angular velocity of rotation of the output shaft of the motor is ω (rad / s), the acceleration / deceleration torque Tα is expressed by the following (Equation 1).

In addition, when the crank shaft is connected to the output shaft of the motor, the rotational movement is changed to reciprocating movement, and the operation of pressing back against the load having spring characteristics is repeated, the motor load torque including during acceleration / deceleration is Tq (Nm). ), The elastic load torque Td with respect to the spring characteristics is expressed by the following (Equation 2). It is said that the friction load, rolling friction, and other loads at this time are so small that they can be ignored.

Further, the inertial load power Pα during the acceleration / deceleration torque in the above (Equation 1) is represented by the following (Equation 3) with the rotation speed as N (min ^ (-1)).

Next, the elastic load power Pd during constant angular velocity operation is represented by the following (Equation 4).

Here, the inertial load storage energy stored in the inertial load when operated with the power Pα given by the above (Equation 3) is expressed by the following (Equation 5) by time-integrating the above (Equation 3).

Similarly, the elastic load storage energy stored in the elastic load when operated with the power Pd given by the above (Equation 4) is expressed by the following (Equation 6) by time-integrating the above (Equation 4).

Therefore, the total load storage energy E obtained by adding the inertial load storage energy Eα and the elastic load storage energy Ed is represented by the following (Equation 7).

When the motor 3 is decelerated and stopped from this state, the energy stored in the inertial load or the elastic load (or the gravitational load) is regenerated energy from the motor load 120 via the motor 3 and the inverse converter 7, for example, an electrolytic capacitor or the like. Return to the storage device 6 such as a storage battery. At this time, the amount of energy stored in the inertial load or the load side is calculated every moment from the start of operation of the motor 3 so that the storage device 6 does not become overcharged, and the amount of energy stored in the storage device 6 is used as the amount of energy. The voltage command calculation circuit 15 is controlled by the control circuit 8 to control the power of the storage device 6 so that the energy generated by the regeneration is deducted and the energy generated by the regeneration is stored in the storage device 6 to be the specified amount of energy. The amount of accumulation is variably controlled.

The amount of energy stored in the inertial load or the load side is not calculated from the physical power, but a control signal detected from the motor 3 or a sensor provided in the configuration for driving the motor 3 is used. This is because the moment of inertia and the elastic load characteristic (or gravity load characteristic) can be accurately obtained from the current, voltage, position, velocity, angular velocity, power, and energy of the motor 3. For example, in the case of an elastic load, the spring characteristics using the restoring force of compressed air have a useful life, and the characteristics deteriorate by the end of the life. However, even in this case, the load characteristics according to the secular variation can be faithfully picked up by the motor 3 and the sensor having the configuration for driving the motor 3. On the contrary, if the spring characteristics are operated with the initial constants and an attempt is made to calculate from the physical power, the state dissociated from the actual characteristics will be calculated, and the control accuracy and the like in the operation of the motor 3 will deteriorate and errors will occur. May occur.

From the law of conservation of energy, the appropriate amount of energy Eref stored in the storage device 6 is expressed by the following (Equation 8), where the energy stored in the storage device 6 when fully charged is Emax (J).

For example, when an electrolytic capacitor having a capacity C (F) is used as the storage device 6, if the appropriate voltage of the electrolytic capacitor is Vref (V), the appropriate energy stored in the electrolytic capacitor is represented by the following (Equation 9). ..

When the above (Equation 9) is substituted into the above (Equation 8) and arranged, the appropriate voltage Vref of the electrolytic capacitor of the accumulator 6 at the time of elastic load is expressed by the following (Equation 10).

Here, the constant k in the above (Equation 10) is represented by the following (Equation 11).

Next, for the gravitational load, consider the torque, power, and stored energy in the same way as the elastic load. The acceleration / deceleration torque under a gravitational load is as described in (Equation 1) above. As the gravitational load, for example, a hoist may be connected to the output shaft of the motor 3, a car or a load may be hung at the tip of a rope, and the car may be moved up and down.

Assuming that the motor torque including acceleration / deceleration is Tq (Nm), the gravity load torque Tw is expressed by the following (Equation 12). It is said that the friction load, rolling friction, and other loads at this time are so small that they can be ignored.

Next, the gravity load power Pw during constant angular velocity operation is represented by the following (Equation 13).

The gravitational load storage energy stored in the gravitational load when operated with the gravitational load power Pw given in the above (Equation 13) is expressed by the following (Equation 14) by time-integrating the above (Equation 13).

Therefore, the total load storage energy E obtained by adding the inertial load storage energy Eα and the gravity load storage energy Ew is represented by the following (Equation 15).

Next, in the case of a gravitational load, the appropriate amount of energy Eref stored in the storage device 6 is expressed by the following (Equation 16), where Emax (J) is the energy stored when the storage device 6 is fully charged.

Further, when an electrolytic capacitor having a capacitance C (F) is used as the storage device 6, the appropriate energy stored in the electrolytic capacitor is represented by the above (Equation 9), so the above (Equation 9) is used. By substituting into the above (Equation 16) and rearranging, the appropriate voltage Vref of the electrolytic capacitor of the accumulator 6 under the gravity load is represented by the following (Equation 17). The proportionality constant k is represented by the above (Equation 11).

Here, when the inertial load energy Eα, the elastic load energy Ed, and the gravity load energy Ew are regenerated, and the regenerative energy is returned from the load side to the storage device 6 via the motor 3 and the inverse converter 7, the regenerative efficiency is 100%. Part of it is consumed as a loss because it does not exist. Therefore, in the calculation at the time of regeneration, the regeneration efficiency is reflected by multiplying the inertial load energy Eα, the elastic load energy Ed, and the gravity load energy Ew by the regeneration efficiency X1 (<1), respectively. By setting = 1, the regeneration efficiency X1 (<1) is set only at the time of regeneration, so that more accurate control can be realized.

For example, when considering an elastic load using the restoring force of compressed air as the motor load 120, the slide descends from the compressed air to store energy in the load, and then when the slide starts to rise, it is regenerated by the ascending speed. The amount of energy is different. This also causes a restoration time for the material that encloses the compressed air, so if the slide is separated first, the motor will not be in a regenerative state because the reaction force from the elastic load disappears. In reality, the slide does not separate from the material surrounding the compressed air, so regenerative energy is generated. However, the amount of power energy when the slide is descending and the amount of regenerative energy when the slide is ascending are not equal, and the amount of energy on the regenerative side is small. In this case, the amount of energy stored on the load side at the start of operation of the motor is calculated every moment, the amount is subtracted from the amount of energy stored in the storage device, and when it is regenerated, the specified amount of energy does not return. do. Therefore, in this case, the weighting coefficient X2 (≠ 1) is multiplied by the energy during power running according to the amount of energy during regeneration. For example, at the start of operation, (amount of energy stored on the load side) × (weighting coefficient X2) is performed to correct the amount of energy stored in the storage device 6 and subtracted by that amount, and at the time of regeneration, ( If the amount of regenerated energy) × (weighting coefficient X2) (however, X2 = 1) is performed and the amount of energy is returned as it is, the subtracted amount will return to the original value.

The coefficient X is the regeneration efficiency X1 at the time of regeneration (however, at the time of regeneration: X1 <1, at the time of powering: X1 = 1) and the weight coefficient X2 at the time of powering (however, at the time of powering: X2 ≠ 1, at the time of powering: X2 = 1). It is expressed by the following (Equation 18).

Here, the appropriate voltage Vref of the accumulator 6 (electrolytic capacitor) under the elastic load shown in the above (Equation 10) and the appropriate voltage Vref of the accumulator 6 (electrolytic capacitor) under the gravity load shown in the above (Equation 17). The voltage Vref is represented by the following (Equation 19) and the following (Equation 20), respectively, using the coefficient X of the above (Equation 18).

In the above (Equation 18), the weighting coefficient X2 is set so that X2 ≠ 1 at the time of power running and X2 = 1 at the time of regeneration, but the weighting coefficient X2 ≠ 1 at the time of regeneration and the weighting coefficient X2 = 1 at the time of power running. It may be set as follows.

As described above, in the case of elastic load and gravity load, inertial load is generated in common for both loads, and the appropriate voltage Vref of the storage device (electrolytic capacitor) is determined in advance by the above (Equation 19) and (Equation 20). Is calculated every moment from the start of operation to the inertial load or the amount of energy stored on the load side, subtracts that amount from the amount of energy stored in the storage device, and returns to the specified amount of energy when regenerated. The DC voltage of the storage device may be variably controlled.

Here, the inertial load, elastic load, gravity load, and the like will be described in detail with specific examples.

FIG. 2 is a diagram illustrating rotational or kinetic energy stored in an inertial load.

As shown in FIG. 2, when electric energy is applied to the inertial body for ta time by a motor or the like, the inertial body is given rotational energy rotating at an angular velocity ω. Here, ignoring losses such as electric circuits, rolling friction, and wind damage, the inertial body continues to rotate forever even if the supply of electric energy is stopped. However, since the loss cannot be ignored in reality, the energy for the loss must be continuously applied as electrical energy in order to maintain the rotation of the inertial body. Next, when the regenerative brake is applied to the inertial body for dt time to remove the rotational energy, the inertial body is stopped and the rotational energy is regenerated and returned to the power source as electric energy. That is, turning the inertial load means converting the electric energy supplied from the power source into rotational energy, and stopping the inertial load by regenerative braking means changing the rotational energy into the form of electric energy again. Yes, these can be said to be the act of transferring the energy storage location.

In FIG. 2, the rotary motion of the crank shaft of the crank press machine is shown as an example of the rotary motion, the slide mass is summarized at the point A, and the mass point that equivalently shows the balance mass due to the balance adjustment is shown at the point B. It is schematically shown as the rotational motion of the fly wheel shown. The energy E stored in such an inertial body is expressed by the following (Equation 21), where the angular velocity of the crank shaft is ω (rad / s) and the moment of inertia of the inertial body is J (kg · m ^ 2). , It can be seen that it is proportional to the moment of inertia J and proportional to the square of the angular velocity ω.

Further, as shown in FIG. 2, in the case of linear motion, the energy E stored as kinetic energy is represented by the following (Equation 22), where m (kg) is the mass of the inertial body and Vl is the moving speed. It can be seen that it is proportional to m and proportional to the square of the moving speed Vl (m / s).

FIG. 3 is a diagram schematically illustrating the structure of a press machine with a pneumatic die cushion.

In FIG. 3, the press has a slide 25 that moves up and down and a fixed bolster 27. The slide 25 moves up and down while being guided by the slide give 26 through the slide drive means 21 and the crank mechanism (crank shaft 22, crank eccentric portion 23). The bolster 27 is fixed on the bed 28, connected to the slide mechanism through the frame of the press machine, and has a structure that receives a pressing force from above. As an example of the slide drive means 21, in the case of the most commonly used crank press, the rotation of the slide motor 20 is transmitted from the crank shaft 22 to the crank eccentric portion 23, and the slide 25 is moved up and down via the connection rod 24. A mold is attached to this press machine and press processing is performed. The upper mold 29 is set on the lower surface of the slide 25, and the lower mold 30 is set on the upper surface of the bolster 27, and a pair of upper and lower molds constitutes one mold. The mold can be processed such as shearing, bending, and squeezing an iron plate, and can give plastic deformation to the iron plate to form a desired shape. The quality and performance of this die play an important role in the productivity and quality of press working. In the pneumatic die cushion device 31 in drawing, for example, in a cup-shaped drawing, compressive stress in the circumferential direction is generated in the flange portion of the molded product as the processing progresses, and wrinkles occur if left unattended. The pneumatic die cushion device 31 is a device that generates the necessary wrinkle pressing pressure from the lower side so that the wrinkles do not occur. The pneumatic die cushion device 31 is built in the bed 28, and the lower mold 30, the die cushion pad (not shown) and the die cushion pin (not shown) operate in conjunction with each other. The pneumatic die cushion device 31 includes a servo die cushion using a servo motor in addition to the pneumatic and hydraulic types.

FIG. 4 is a diagram illustrating the energy stored in the pneumatic die cushion.

As shown in FIG. 4, the die cushion is a pressure holding device that generates a reaction force for pressing wrinkles in drawing and a pushing force of a molded product. Pneumatic die cushions are equivalently replaced by air springs. When a spring deforms, energy is stored in the spring in the form of elastic energy. By releasing the stored energy, the spring can be made to do mechanical work. Air springs, which are materials that generate the restoring force of air, are one of them, and are used in pneumatic die cushions.

When energy is stored in the pneumatic die cushion device 31, the slide 25 moves in the downward direction to compress the air in the pneumatic die cushion, and elastic energy is stored in this portion, and at the same time, a reaction force in the slide direction is applied. Occur. Since the reaction force 31E increases as the slide 25 is pushed downward, it can be considered by replacing it with a spring having a spring constant k (N / m), and the displacement when pushed by the slide 25 is x (. If m), the stored elastic energy E is given by the following (Equation 23).

FIG. 5 is a diagram illustrating energy stored in the elevating device.

As shown in FIG. 5, in the elevating device 82 (described later), the hoisting machine 76 is connected to the motor output shaft, and the luggage (or the basket for accommodating the luggage or the like) 77 is hung from the tip of the rope 78 to perform the elevating operation. .. In FIG. 5, when the load 77 having a mass of m (kg) is on the ground, the energy is in an open state. When the luggage 77 is wound up to a height h (m) from this state, potential energy mgh (J) is stored. When the luggage 77 rises, it moves in the direction opposite to the direction of gravity acting on the luggage 77, so that the motor operates in a power running state, and potential energy is stored in the luggage 77. Further, when the luggage 77 is lowered, the motor is operated in a regenerative state because the luggage 77 is lowered while being suppressed from falling due to gravity, and the potential energy stored in the luggage 77 is released.

FIG. 6 is a diagram illustrating the relationship between the crank shaft angular velocity and the slide speed of the crank press machine.

FIG. 6 shows a case where the crank shaft is rotated 360 ° (1 rotation) from the top dead point to the top dead point via the bottom dead point in the rotation direction, and the time t (s) is shown on the horizontal axis. The vertical axis shows the crank axis angular velocity ω (rad / s), the slide position θs (mm), and the slide speed Vs (m / s), respectively. The slide speed Vs becomes zero speed when the slide position is the midpoint, and the positive side of the slide speed indicates the ascending speed and the negative side indicates the descending speed. In FIG. 6, the slide position is a cosine curve, but the slide speed is a sine curve with a phase delay of 180 ° because the connecting point of the connecting rod of the crank shaft rotates.

The action and effect in the present embodiment configured as described above will be described.

The prior art includes a low cost, low loss and high density power supply device by variably setting the control command value of the storage device based on the rotational energy or spring energy stored in the motor and the motor load. This conventional technique is effective for a power supply device that variably controls the voltage of the storage device for the energy stored in the inertial load. However, the energy stored in other than the inertial load has not been specifically shown, and the energy stored in the elastic load by a spring or the like has not been clarified.

In another conventional technique, in a servo press device having a slide that is variably driven by an AC motor, a control pattern that controls the charge / discharge state of the energy storage device based on the operation pattern of the press machine is selected to supply power. There is a technique for optimizing the capacity of the energy storage device while reducing the size and efficiency of the converter. This conventional technique is a system in which an operation pattern of a press machine and a control pattern for controlling the charge / discharge state of an energy storage device based on this operation pattern are registered in advance, and an operation command is given in synchronization with the operation pattern and the control pattern. It is valid. However, there is a problem that the method of responding to the synchronized operation command of the operation pattern and the control pattern in the case of an independent setting device or an operation command set each time is not clarified.

Further, in another conventional technique, in an inverter in which an AC power source is rectified and converted into a DC fixed voltage, the regenerated energy is consumed by a resistor of a regenerative braking circuit, and a technique relating to abnormal processing and display of a regenerative braking state is performed. There is. This conventional technique is effective for error handling and display of the regenerative braking state of an inverter that uses an AC power supply as a rectifier circuit and has a fixed DC voltage. However, since the regenerated energy is consumed by the resistor of the regenerative braking circuit, there is a problem in improving the environment against global warming.

In response to such problems in the prior art, according to the present embodiment, it is possible to distinguish whether the load during operation is an inertial load or an elastic load, or whether it is an inertial load or a gravity load, and in the case of an inertial load. In the case of an elastic load that generates a reaction force, the amount of power stored in the storage device is variably controlled with respect to the case of a gravity load that moves up and down, so excessive storage of power in the storage device is possible. It can be suppressed, power loss can be reduced, and the storage device can be downsized. In addition, the operation pattern of the press machine, which is a load, and the control pattern that controls the charge / discharge state of the energy storage device based on this operation pattern can be registered in advance, or the operation pattern and the control pattern can be synchronized to give an operation command. unnecessary. Further, it is not necessary to consume the regenerated energy in the resistor of the regenerative braking circuit.

That is, in the present embodiment, the load of the motor 3 is the inertial load, the elastic load, and the gravity load, energy is stored on the load side at the same time as the operation, and the electric power having the storage device 6 on the input side of the inverse converter 7. In the conversion system, the speed and current of the motor 3 are detected by the detector together with the operation of the motor 3, the amount E of the energy stored on the load side is calculated, and the energy command value stored in the storage device 6 is Eref, when fully charged. When the energy of the storage device 6 is set to Emax, the energy stored in the storage device 6 is optimized by calculating the energy command value Elef = (Emax-E) stored in the storage device 6, and the power conversion system. It is possible to realize miniaturization, high efficiency, and low cost.

A first embodiment of the present invention will be described with reference to FIGS. 7 to 18.

FIG. 7 is a diagram schematically showing an example of the power conversion system according to the present embodiment.

In this embodiment, a case where a press machine with a pneumatic die cushion is used as a load and driven by a motor is illustrated.

In FIG. 7, the power conversion system controls the operation of the motor 3 by converting the power supplied from the power supply 11 to the motor 3, and is roughly configured from the power supply device 1 and the motor power conversion device 2. ing.

The power supply device 1 is a buck-boost power supply circuit that controls a forward converter 4 that converts the power supplied from the power supply 11 as an AC voltage into a DC voltage GBP and a voltage GBP of the power converted into a DC voltage by the forward converter 4. 5 and the voltage-controlled power of the buck-boost power supply circuit 5 are stored and supplied to the motor power conversion device 2, and the power generated by the regenerative operation of the motor 3 and supplied via the motor power conversion device 2 is supplied. It includes a storage device 6 (for example, a capacitor, a storage battery, etc.) for storing, and a voltage command calculation circuit 15 that controls the operation of the buck-boost power supply circuit 5 to control the voltage GBP. Here, the buck-boost power supply circuit 5 and the voltage command calculation circuit 15 constitute a power storage device control circuit that controls the amount of power stored in the storage device 6 from the power supply 11 based on the stored energy and the maximum power amount. There is.

The motor power conversion device 2 controls the operation of the motor 3 by converting the power supplied from the buck-boost power supply circuit 5 of the power supply device 1 to the motor 3 via the storage device 6, and also controls the operation of the motor 3. The operation of the inverse converter (inverter) 7 that supplies the power generated by the regenerative operation to the storage device 6 of the power supply device 1 and the inverse converter 7 is controlled, and the power is obtained via the encoder 10 provided in the motor 3. The angular speed of the motor 3 to be mounted, the torque of the motor 3 calculated based on the current values detected by the current detectors 59 and 60 (described later) provided in the motor 3, and the inertial moment related to the preset motor 3. Based on the above, the control circuit 8 calculates the stored energy, which is the energy stored in the motor 3 and the motor load driven by the motor 3 (here, the press machine 12 with a pneumatic die cushion), and the control circuit 8 calculates. The buck-boost power supply circuit 5 is controlled based on the stored energy and the maximum power amount predetermined as the maximum value of the power amount that can be stored in the storage device 6, and is stored in the storage device 6 from the power supply 11. It is provided with a voltage command calculation circuit 15 that controls the amount of power to be generated. The control circuit 8 generates a gate signal based on the detection results from the current detectors 59 and 60 of the inverse converter 7, the encoder 10 of the motor 3, and the like, and controls the inverse converter 7 with the gate signal to control the motor 3. A position speed current control circuit 16 that controls the drive of the motor 3 and calculates the angular speed and torque of the motor 3, and a press machine 12 with a pneumatic die cushion that is a motor load based on the calculation results of the position speed current control circuit 16. It has a stored energy calculation circuit 14 (calculation circuit) for calculating stored energy.

The motor 3 for driving the slide 25 of the press machine 12 with a pneumatic die cushion (hereinafter, may be simply referred to as a press machine 12) is composed of an AC motor 9 and an encoder 10 provided in the AC motor 9. The speed, position, and magnetic pole position of the AC motor 9 are detected by the encoder 10 and fed back to the position / speed / current control circuit 16 of the control circuit 8 of the motor power conversion device 2. In the position / velocity current control circuit 16, the signal (speed, position, magnetic pole position) fed back from the encoder 10 is compared and calculated with the motor drive command from the host device 13, and the slide of the press machine 12 driven by the motor 3 is calculated. A PWM signal is generated and output to the inverse converter 7 so as to follow the 25 according to the motor drive command. The inverse converter 7 drives an AC motor 9 by inputting a DC voltage (voltage between PNs) supplied from the power supply device 1 and converting it into an AC variable voltage and an AC variable current, and drives the AC motor 9, and the position, speed, and position of the motor. Control the current. The current of the AC motor 9 is detected by the current detectors 59 and 60 (described later) in the inverse converter 7, and is fed back to the position / speed current control circuit 16 to be used for calculation of torque and the like.

The power supply device 1 inputs AC power from the power supply 11, converts AC to DC voltage by the forward converter 4, and inputs DC voltage to the buck-boost power supply circuit 5. The buck-boost power supply circuit 5 applies a variable DC voltage to the inverse converter 7 by boosting, stepping down, or buckling the DC voltage. The buck-boost power supply circuit 5 is controlled by the voltage command calculation circuit 15. The voltage command calculation circuit 15 receives the signal E calculated by the control circuit 8 of the motor power conversion device 2, and controls the buck-boost power supply circuit 5 with variable voltage so that the DC voltage GBP of the storage device 6 becomes the optimum voltage. do. Further, the storage device 6 is installed between the buck-boost power supply circuit 5 and the inverse converter 7, and the electric energy supplied from the power source 11 or the press machine 12 via the motor 3, the inverse converter 7, and the like. Accumulates the regenerative energy supplied.

Next, the outline of the control operation of the entire power conversion system will be described. First, the energy stored in the inertial load of the press machine 12 will be described. When a motor drive command is given from the host device 13, the motor 3 starts the raising / lowering operation of the slide 25 according to the command. When the slide 25 starts to move up and down, the amount of stored energy of the inertial load stored in the moment of inertia including the motor 3 and the mechanism portion connected to the load is calculated in real time. When both the slide 25 and the pneumatic die cushion device 31 start to move up and down, the amount of stored energy of the inertial load stored in the moment of inertia including the pneumatic die cushion device 31 is calculated in real time. Next, even if the regenerative energy returns when the regeneration is stopped, the storage capacity of the storage device 6 must be prevented from overflowing. Therefore, at the same time as the movement starts, the capacity of the energy stored in the storage device 6 is controlled to be lowered in advance. In this controlled state, a regeneration stop command is sent from the host device 13 as a motor drive command, and even if the regenerative energy actually returns, it returns to the original energy state level before the start of operation. Therefore, the storage device 6 Will not be overcharged.

The stored energy calculation described above is performed by the stored energy calculation circuit 14 in the control circuit 8 of the motor power conversion device 2, and the control of the optimum value of the energy capacity of the storage device 6 is performed by the PN relocated to the voltage of the storage device 6. It is performed by the voltage command calculation circuit 15 of the power supply device 1 as the inter-voltage command Vref.

Next, the detailed operation of the stored energy calculation circuit 14 of the motor power conversion device 2 and the voltage command calculation circuit 15 of the power supply device 1 will be described. The signals input from the position / velocity current control circuit 16 are the angular velocity detection signal ω detected by the encoder 10, the torque detection signal Tq, and the moment of inertia J. First, the energy stored in the inertial load will be described. The angular velocity signal ω of the motor 3 is calculated by the acceleration / deceleration torque calculation circuit 42, and the acceleration / deceleration torque Tα is calculated by the calculation of the above (Equation 1). The output Tα of the acceleration / deceleration torque calculation circuit 42 calculates the product of the angular velocity signal ω and the acceleration / deceleration power calculation circuit 43 and outputs the acceleration / deceleration power Pα. The acceleration / deceleration power Pα performs a time integration calculation according to the above (Equation 5) in the inertial load storage energy calculation circuit 44, and outputs the inertial load storage energy Eα. The acceleration / deceleration power calculation circuit 43 and the inertial load storage energy calculation circuit 44 are referred to as the inertial load storage energy calculation block 40.

Next, the energy stored in the elastic load will be described. The torque detection signal Tq and the output Tα of the acceleration / deceleration torque calculation circuit 42 perform the difference calculation shown in the above (Equation 2) by the addition / subtraction calculator 51, and output the elastic load torque Td. The elastic load torque Td and the angular velocity signal ω are calculated by the elastic load power calculation circuit 45 to calculate the product of the above (Equation 4), and the elastic load power Pd is output. The elastic load power Pd performs a time integration calculation according to the above (Equation 6) in the elastic load storage energy calculation circuit 46, and outputs the elastic load storage energy Ed. The elastic load power calculation circuit 45 and the elastic load storage energy calculation circuit 46 are referred to as an elastic load storage energy calculation block 41.

The signals input to the inertial load storage energy calculation circuit 44 and the elastic load storage energy calculation circuit 46 include CLR1 and CLR2 output from the position / velocity current control circuit 16. The integral clear signals CLR1 and CLR2 signals are signals that clear the output of the integral calculation circuit, that is, the inertial load storage energy calculation circuit 44 or the elastic load storage energy calculation circuit 46. Further, the position / velocity current control circuit 16 outputs the total value J of the rotor moment of inertia of the AC motor 9 and the moment of inertia on the load side of the motor 3 converted to the motor shaft to the acceleration / deceleration torque calculation circuit 42.

The output Eα of the inertial load storage energy calculation block 40 and the output Ed of the elastic load storage energy calculation block 41 are subjected to the addition calculation of the above (Equation 7) by the addition calculator 50, and are sent to the voltage command calculation circuit 15 of the power supply device 1. It is output as the total load storage energy E. In the voltage command calculation circuit 15 of the power supply device 1, a value Emax is set as the energy at the time of full charge of the storage device 6 in the energy setting block 47 at the time of full charge, and the motor power conversion device is set by this value Emax and the addition / subtraction calculator 51. The difference from the total load stored energy E output from the stored energy calculation circuit 14 of 2, that is, the appropriate energy Elef stored in the storage device 6 is derived by the above (Equation 8).

Here, for example, when the electrolytic capacitor C is used as the storage device 6, after multiplying Eref, which is the output of the addition / subtraction calculator 51, by k = 2 / C represented by the above (Equation 11) in the proportional coefficient block, When the square root calculation is performed by the square root calculation circuit 49, the voltage command Vref for the storage device 6 shown in the above (Equation 10) is obtained. Further, the voltage across the accumulator 6 GBP (voltage between PNs) is divided by the resistor 56 (described later) having a resistance value R1 and the resistor 57 (described later) having a resistance value R2 connected in series, and the detected value (feedback). Voltage) Vf is detected, and is fed back after electrical insulation is performed by the insulation amplifier 18. After that, the voltage command Vref and the feedback voltage Vf of the storage device 6 perform a difference calculation of Vref-Vf with the addition / subtraction calculator 51. This difference voltage is proportionally integrated by the PI regulator 17, and the inverse converter 7 is controlled via the drive circuit 61 (described later) of the position / velocity current control circuit 16 to control the output voltage of the step-up / down power supply circuit 5. The VDC, that is, the output voltage of the storage device 6 is feedback-controlled according to the value of the voltage command Vref.

FIG. 8 is a diagram showing a detailed example of a forward converter, a buck-boost power supply circuit, and a storage device of the power supply device, and shows a case where a circuit that performs a boosting operation is used as the buck-boost power supply circuit.

That is, it can be said that the step-up / down power supply circuit 5 in FIG. 8 is a step-up power supply circuit that exhibits a boosting operation.

The forward converter 4 rectifies the AC voltage supplied from the AC power supply 11 by the full-wave rectifier 55, converts it into a substantially constant DC voltage determined by the received voltage, and smoothes it by the smoothing capacitor 52. The smoothed DC voltage is connected to a switching element 53 that repeats ON / OFF via a step-up reactor 58 in a step-up / down pressure power supply circuit 5 that is a step-up power supply circuit. When the switching element 53 is turned on, the current flowing through the step-up reactor 58 increases, and when the switching element is turned off next time, the current flowing from the step-up reactor 58 to the switching element 53 is switched to the diode 54 side, and the output voltage GBP is DC. The voltage e = −L · (dI / dt) generated across the booster reactor 58 is added to the voltage (voltage between P0 and N) to boost the voltage. The switching element 53 is repeatedly turned on and off, and the step-up / down power supply circuit 5 capable of variable control of the boost voltage is configured by changing the conduction ratio thereof. A smoothing capacitor 52 is connected to the output of the buck-boost power supply circuit 5 as a storage device 6, and electric energy charged from the AC power supply 11 and regenerative energy regenerated from the load side are stored. In FIG. 8, a smoothing capacitor 52 is used for the storage device 6, but a large-capacity electrolytic capacitor is connected in parallel to increase the capacity, but a secondary battery, an electric double layer capacitor, or the like can also be used. good.

FIG. 9 is a diagram showing other examples of details of the forward converter of the power supply device, the buck-boost power supply circuit, and the storage device, and shows a case where a circuit that performs a step-down operation is used as the buck-boost power supply circuit.

That is, it can be said that the step-down power supply circuit 5A in FIG. 9 is a step-down power supply circuit that exhibits a step-down operation.

The forward converter 4 rectifies the AC voltage supplied from the AC power supply 11 by the full-wave rectifier 55, converts it into a substantially constant DC voltage determined by the received voltage, and smoothes it by the smoothing capacitor 52. Next, there is a switching element 53 at the inlet that repeats ON / OFF, and when the switching element 53 is turned ON, the step-down reactor 58A and the load are connected in series, so the voltage is divided and given, and the step-down is performed by changing the ON / OFF conduction ratio. A buck-boost power supply circuit 5A that operates as a step-down power supply circuit capable of variable voltage control is configured. A smoothing capacitor 52 is connected to the storage device 6 at the output, and electric energy charged from the AC power supply 11 and regenerative energy regenerated from the load side are stored. The capacity of the smoothing capacitor 52 is increased in the same manner as in FIG.

FIG. 10 is a diagram showing details of an inverse converter of a motor power converter and a position / velocity current control circuit.

In FIG. 10, an AC servo amplifier, a vector control inverter, an inverter, and a DCBL controller are used as the motor power conversion device 2, and these are collectively referred to as a motor power conversion device 2.

The inverse converter 7 has one arm in which two sets of anti-parallel circuits of the switching element 53 and the diode 54 are connected in series, and the three arms are connected in parallel to form a three-phase inverter. Although the case of configuring a three-phase inverter is illustrated in FIG. 10, another multi-phase inverter may be configured. The intermediate terminal of each arm is connected to the motor terminal of the motor 3, and the U-phase current detector 59 and the W-phase current detector 60 are connected to two of the two phases (U-phase and W-phase), respectively. The U-phase current detector 59 and the W-phase current detector 60 may be combined and simply referred to as current detectors 59 and 60.

As the AC motor 9, a permanent magnet type motor, an inductive motor, a DC brushless motor (DCBL motor), or the like is used. The AC motor has a shaft at the center of the cylinder, and is not caught only by the permanent magnet type motor or the induction type motor in which this shaft rotates. For example, a linear motor may be used in which one part on the stator side of the circumference of the AC motor 9 is cut open to make a straight line and the rotating portion has a linear reciprocating motion. As the AC servo amplifier, vector control inverter, inverter, and DCBL controller that drive the linear motor, the AC motor 9 can be used as it is. In the case of a linear motor, instead of the encoder 10, a linear sensor scale is installed in the fixed portion and a linear sensor head is installed in the moving portion so as to face each other on the moving path, and the position and speed are detected. If the magnetic pole position detection signal of the magnet is required, it can be handled by attaching a magnetic pole position detection sensor. A linear motor driven by an AC servo amplifier is also called a linear servo motor. In the following description, the AC motor 9 shall include a linear motor unless otherwise specified.

The output of the encoder 10 attached to the output shaft of the AC motor 9 is input to the position / velocity magnetic pole position calculation circuit 62, the rotation speed N which is one of the calculation results is output to the feedback, and the other one of the calculation results. The magnetic pole position signal θ is output to the 3-phase / dq conversion circuit 68 and the dq / 3-phase conversion circuit 66.

The rotation speed N is output from the host device 13, and the speed command Ns in the motor drive command passes through the mode changeover switch 74 (Mod2), and the deviation ε = Ns—N is calculated by the addition / subtraction calculator 51. The deviation ε is amplified by the speed control circuit (ASR) 63, passes through the mode changeover switch (Mod1), and is output as the torque current command Iq. The mode changeover switch 73 (Mod1) switches the motor drive command to the torque command Ts when it is ON, and switches to the position command or the speed command when it is OFF. Further, the mode changeover switch 74 (Mod2) switches the motor drive command to the position command θs when it is ON, and switches to the speed command Ns when it is OFF. The mode in which the motor drive command is switched is instructed by the host device 13 to the CPU 72 of the position / speed current control circuit 16 of the motor power conversion device 2, and the CPU 72 switches the mode. That is, the CPU 72 not only controls the outputs of the integrated clear signals CLR1 and CLR2, but also controls the operation of the entire 16 based on the command from the host device 13.

The detection results of the current detectors 59 and 60 are input to the 3-phase / dq conversion circuit 68 as current feedback signals If and Iwf of the AC motor 9, and the d-axis current negative feedback signal is two vector signals whose dq axes are orthogonal to each other. It is converted into Idf and a torque current feedback signal Iqf. The torque current command Iq is input to the addition / subtraction calculator 51 that calculates the difference from the torque current feedback signal Iqf, and the deviation is amplified by the q-axis current control circuit (ACR) 65. The d-axis current command Id is a current command for field weakening control, and is input to the addition / subtraction calculator 51 that calculates the difference from the d-axis current negative feedback signal Idf, and the deviation is input to the d-axis current control circuit (ACR). It is amplified at 64. The d-axis current command Vd, which is the output of the d-axis current control circuit (ACR) 64, and the q-axis voltage command Vq, which is the output of the q-axis current control circuit (ACR) 65, are input to the dq / 3-phase conversion circuit 66. It is converted into three-phase voltage commands Vu, Vv, Vw and output to the PWM circuit 67, and is output from the PWM circuit 67 as a gate signal for driving the six switching elements 53 of the inverse converter 7 via the drive circuit 61. As a result, the motor 3 is controlled according to the motor drive command.

For the total value J = Jm + Jl of the moment of inertia Jm of the AC motor 9 and the moment of inertia Jl on the load side of the motor 3 converted to the motor shaft, the calculated moment of inertia J is input to the parameter of the motor power conversion device 2 during the trial run. Alternatively, it can be tuned by the auto-tuning function of the moment of inertia J by the trial run function of the motor power converter 2. Further, if the motor power converter 2 has a function of tuning the moment of inertia J in real time during operation (real-time auto-tuning function), the value tuned in real time is updated even if the moment of inertia J changes due to the function. can do. The CPU 72 of the position / speed current control circuit 16 outputs the moment of inertia J stored and updated in the parameter area 75 by tuning or the like to the acceleration / deceleration torque calculation circuit 42 of the stored energy calculation circuit 14, and the acceleration / deceleration torque calculation circuit 42 The moment of inertia J used can be updated in real time. As for these parameters, the value at that time is written from the RAM memory to the non-volatile memory when the power is turned off, and the moment of inertia J which is read from the non-volatile memory to the RAM memory and updated at the next power-on is inherited. ..

FIG. 11 is a diagram showing an example of the waveform of the angular velocity detection signal of the slide motor when drawing is performed by a press machine with a pneumatic die cushion.

In this embodiment, the angular velocity detection signal ω and the torque detection signal Tq of the slide motor are output from the position speed current control circuit 16. In drawing, a blank material is sandwiched between the upper die on the slide 25 side and the lower die on the pneumatic die cushion device 31 side, and the slide torque from above and the push-up reaction force from below by the pneumatic die cushion device 31. Apply compressive force to the blank material from both the top and bottom. As shown in FIG. 11, at the beginning of drawing, the slide 25 starts descending at high speed from top dead center and decelerates to medium speed immediately before contacting the pneumatic die cushion device 31. After reaching medium speed, after entering drawing and passing through bottom dead center, the slide 25 starts to rise and separates from the pneumatic die cushion device 31, and then the angular velocity detection signal ω accelerates again at high speed and stops at top dead center. do. Here, the rotation direction of the slide motor (motor 3) is one-way operation, but the operation direction of the slide 25 switches between descending and ascending (see FIG. 6). Note that FIG. 11 shows the timing of drawing in the range of the arrow as the drawing period is in progress at medium speed.

FIG. 12 is a diagram showing an example of the waveform of the torque detection signal of the slide motor when drawing is performed by a press machine with a pneumatic die cushion.

As shown in FIG. 12, the slide torque (torque detection signal) Tq when drawing is not performed is such that the acceleration torque is generated on the positive side during acceleration and the deceleration torque is generated on the negative side during deceleration, that is, Acceleration / deceleration torque is generated only when the angular velocity changes. During the drawing period, the slide 25 gradually pushes the compressed air of the pneumatic die cushioning device 31 while descending, so that elastic energy is stored and the torque (torque detection signal Tq) of the slide motor gradually increases in the positive direction. Increases to. At the bottom dead center, the pressing torque becomes zero, but the reaction force from the pneumatic die cushion device 31 is received. When it passes through the bottom dead center and starts to rise, the slide torque (torque detection signal) Tq maintains a medium speed due to the increased reaction force of the pneumatic die cushion device 31, so that the slide torque (torque detection signal) Tq switches to the regenerative braking torque and becomes a negative direction. When the slide 25 is separated from the pneumatic die cushion device 31, the stored elastic energy is released and the regenerative torque rapidly decreases to zero. In FIG. 12, the die cushion torque is generated in the portion indicated by the range of the arrow during the drawing period.

FIG. 13 is a diagram showing an example of the output waveform of the acceleration / deceleration torque calculation circuit when drawing is performed by a press machine with a pneumatic die cushion.

The output waveform of the acceleration / deceleration torque calculation circuit 42 is a waveform obtained by differentiating the angular velocity detection signal ω of the slide motor and multiplying it by the moment of inertia J. Therefore, as shown in FIG. 13, when the angular velocity detection signal ω is constant, the output becomes zero, and since the angular velocity detection signal ω is constant during the drawing period, the die cushion torque does not appear. Therefore, as the output waveform of the acceleration / deceleration torque calculation circuit 42, a waveform obtained by separating only the acceleration / deceleration torque of the slide motor can be obtained. Normally, the detection based on the current waveform of the motor 3 includes the full load current, so that it is impossible to detect only the acceleration / deceleration torque separately. That is, it is one of the features of this embodiment that only the acceleration / deceleration torque can be separated by calculation.

FIG. 14 is a diagram showing an example of the output waveform of the addition / subtraction calculator when drawing is performed by a press machine with a pneumatic die cushion.

The output Td of the addition / subtraction calculator 51 is represented by a torque detection signal Tq − acceleration / deceleration torque Tα. For example, in the case of drawing with a press machine 12 with a pneumatic die cushion, the main torque of the slide motor is the acceleration / deceleration torque for accelerating and decelerating the load moment of inertia, and drawing with the slide 25 and the pneumatic die cushion device 31. It is almost two of the die cushion torque. Generally, the torque component of all the loads applied to the motor 3 appears in the torque detection signal Tq of the motor 3, but the die cushion torque during drawing is equal to the elastic load torque Td, so as shown in FIG. , The elastic load torque Td is calculated by the slide motor torque (torque detection signal) Tq-acceleration / deceleration torque Tα.

As shown in FIGS. 13 and 14, in this embodiment, the slide motor torque (torque detection signal) Tq is the acceleration / deceleration torque Tα generated in the inertial load and the elastic load torque Td generated in the elastic load. It has the characteristic that it is detected separately in two.

FIG. 15 is a diagram showing an example of the output waveform of the inertial load storage energy calculation circuit when drawing is performed by a press machine with a pneumatic die cushion.

The inertial load stored energy Eα, which is the output of the inertial load stored energy calculation circuit 44, calculates the acceleration / deceleration power Pα by multiplying the angular velocity detection signal ω of the slide motor by the acceleration / deceleration torque Tα in the acceleration / deceleration power calculation circuit 43. It is calculated by integrating the acceleration / deceleration power Pα over time. The inertial load stored energy Eα showing the waveform shown in FIG. 15 is integrated or subtracted only when the angular velocity detection signal ω (see FIG. 11) of the slide motor is changing. Therefore, the angular velocity detection signal ω is constant. It is not integrated during a certain drawing period, that is, when a die cushion torque is generated.

FIG. 16 is a diagram showing an example of the output waveform of the elastic load storage energy calculation circuit when drawing is performed by a press machine with a pneumatic die cushion.

The elastic load storage energy Ed, which is the output of the elastic load storage energy calculation circuit 46, is calculated by multiplying the angular speed ω of the slide motor by the elastic load torque Td in the elastic load power calculation circuit 45 to calculate the elastic load power Pd. It is calculated by integrating the power Pd over time. The elastic load storage energy Ed whose waveform is shown in FIG. 16 has a shape obtained by integrating the waveform of the elastic load torque Td (see FIG. 14) because the angular velocity detection signal ω of the slide motor is constant at the medium speed during the drawing period.

As shown in FIGS. 15 and 16 above, in this embodiment, the inertial load storage energy Eα stored in the slide motor and its load and the elastic load storage energy Ed stored in the pneumatic die cushion device 31 are used. Is calculated individually.

FIG. 17 is a diagram showing an example of the output waveform of the addition calculator of the stored energy calculation circuit when drawing is performed by a press machine with a pneumatic die cushion.

As shown in FIG. 17, the total load storage energy E, which is the output of the addition calculator 50, is the waveform itself in which the inertial load storage energy Eα (see FIG. 13) and the elastic load storage energy Ed (see FIG. 14) are added. Is.

FIG. 18 is a diagram showing an example of the output waveform of the voltage command calculation circuit when drawing is performed by a press machine with a pneumatic die cushion.

The output of the voltage command calculation circuit 15 is an output voltage command Vref for controlling the buck-boost power supply circuit 5. In the voltage command calculation circuit 15, first, in the addition / subtraction calculation unit 51, the total load storage energy E, which is the output of the storage energy calculation circuit 14 of the control circuit 8 (that is, the output of the addition calculation unit 50), is fully charged in the storage device 6. It is subtracted from the time energy Emax. Since the energy Emax at the time of full charge of the storage device 6 is the maximum value at the time of full charge but is a constant value, the output of the addition / subtraction calculator 51 is the proportional coefficient block 48 by multiplying the proportional coefficient k (= 2 / C). And the unit of voltage (V) from energy (J) via the square root calculation circuit 49. As a result, as shown in FIG. 18, the output voltage command Vref is obtained as a waveform obtained by subtracting the waveform of the total stored energy E (see FIG. 17) from the constant value.

As shown in FIG. 18, in the drawing process, the voltage Vref of the accumulator 6 changes from the acceleration of the angular velocity detection signal ω when the slide motor descends to the high speed to the medium speed, and the voltage Vref of the storage device 6 is an inertial load when accelerating to a high speed. Since it is gradually stored in, the voltage of the storage device 6 is gradually lowered so that it can be regenerated immediately, the voltage Vref is maintained when the angular velocity detection value ω is constant, and part of the energy is used when decelerating to medium speed. Since it is regenerated, the voltage Vref is returned and raised by that amount. During the next drawing process, the elastic load energy supplied from the power source 11 by the pneumatic die cushion device 31 becomes large, so that the voltage Vref of the storage device 6 is greatly reduced. Further, when the total energy E exceeds the peak, this elastic load energy turns to regeneration, so that the voltage Vref of the storage device 6 returns to an increase this time. Then, when the drawing process is completed, the operation of the inertial load storage energy is started again, and the same operation as in the first high-speed operation is performed in the order of medium speed → high speed → stop.

As shown in FIGS. 11 to 18 above, in this embodiment, the voltage command Vref of the storage device 6 is variably controlled according to the energy stored in the inertial load and the energy stored in the elastic load.

A second embodiment of the present invention will be described with reference to FIG. In this embodiment, only the differences from the first embodiment will be described, and in the drawings used in the present embodiment, the same members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, the power supply device is built in the motor power conversion device, and the voltage of the storage device is variably controlled based on the inertial load storage energy.

FIG. 19 is a diagram schematically showing an example of the power conversion system according to the present embodiment.

In this embodiment, the power storage element 6A is used instead of the storage device 6 of the first embodiment, and the injection molding machine is driven by a motor as a load.

In FIG. 19, the motor power conversion device 2A of the power conversion system of this embodiment includes a forward converter 4, a buck-boost power supply circuit 5, a power storage element 6A, an inverse converter 7, a control circuit 8, and a voltage command calculation circuit 15. It is equipped with. Further, the control circuit 8 includes a stored energy calculation circuit 14A (calculation circuit) and a position / velocity current control circuit 16A.

The stored energy calculation circuit 14A of this embodiment outputs the acceleration / deceleration torque Tα, which is the output of the acceleration / deceleration torque calculation circuit 42, and the elastic load torque Td (output of the acceleration / subtraction calculator 51) to the position / velocity current control circuit 16A. It is configured as follows. In general, the torque detection signal of a motor shows the torque component of all the loads applied to the motor. On the other hand, in this embodiment, since it is possible to separate the acceleration / deceleration torque Tα generated in the inertial load and the elastic load torque Td generated in the elastic load, the acceleration / deceleration torque Tα and the elasticity can be separated. The load torque Td and the load torque Td are fed back to the position speed current control circuit 16A. The position / velocity current control circuit 16A has a function of taking in the acceleration / deceleration torque Tα and the elastic load torque Td from the stored energy calculation circuit 14A, that is, a separated monitor torque function.

Further, the position / velocity current control circuit 16A outputs the captured acceleration / deceleration torque Tα and the elastic load torque Td to the host device 13. In the host device 13, the acceleration / deceleration torque Tα and the elastic load torque Td are used for examining what kind of power is to be reduced in order to save energy. That is, it is measured individually by operating under various conditions such as whether to reduce the inertial load power, the elastic load power, the tact time, or the elastic load torque. It can be examined with reference to the acceleration / deceleration torque Tα and the elastic load torque Td.

In FIG. 19, the injection shaft 34 of the injection molding machine 35 is illustrated as a load for a general industrial machine. Since the injection shaft 34 as a motor load does not store energy, which is not an elastic load or a gravity load, except for an inertial load, the elastic load storage energy calculation circuit 46 always turns on the CLR2 of the integral clear signal 2 and sets its output to zero. To disable. However, the inertial load storage energy calculation circuit 44 is enabled to perform the energy storage calculation. The integral clear signals CLR1 and CLR2 can be set to be always ON from the outside by parameters, and can be set to be ON when the load cannot store energy. The ON setting can also be set from the host device 13.

Other configurations are the same as those in the first embodiment.

In the present invention, even if the regenerative energy returns to the power storage device, it is not overcharged. Therefore, when the power storage element 6A (for example, an electrolytic capacitor) is used as the power storage device, the voltage preset in the power storage element 6A is used. The upper limit margin of the range can be reduced to raise the upper limit of the voltage range, the energy that can be stored can be increased without increasing the capacity of the electrolytic capacitor, and the loss can be further reduced. Therefore, as in this embodiment, the forward converter 4, the buck-boost power supply circuit 5, and the power storage element 6A (electrolytic capacitor) can be built in the motor power converter 2A.

Further, the block up to the appropriate voltage Vref output of the storage element 6A (electrolytic capacitor) of the stored energy calculation circuit 14 and the voltage command calculation circuit 15 in the control circuit 8 shown in FIG. 19 and the PI regulator 17 are software processing and are positioned. Since the CPU 72 of the speed / current control circuit 16A is processing, there is no need to add a new CPU.

A third embodiment of the present invention will be described with reference to FIGS. 20 and 21. In this embodiment, only the differences from the first embodiment will be described, and in the drawings used in this embodiment, the same members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, a press machine 12A with a servo die cushion, which has a slide 25 and a servo die cushion device 32 as a motor load and uses a separate power supply system for the slide 25 and the servo die cushion device 32, is used. be.

FIG. 20 is a diagram schematically showing an example of a power conversion system according to this embodiment.

In FIG. 20, the pneumatic die cushion device 31 is replaced with the servo die cushion device 32 with respect to the first embodiment (FIG. 7), a reaction force is applied from the lower side by the die cushion motor 103, and the die. The cushion motor 103 is configured to be controlled by a die cushion motor power conversion device 121 (AC input).

The die cushion motor 103 has an encoder 110 built in the AC motor 109. Further, since the motor power conversion circuit 107 of the die cushion motor power converter 121 (AC input) has built-in functions (not shown) such as a forward converter and a reverse converter, a three-phase AC AC power supply 11 Power is supplied from, and a constant DC voltage is given to the input of the inverse converter. That is, the motor power conversion circuit 107 is a standard motor power conversion device without a buck-boost power supply circuit.

In addition, in FIG. 20, the wiring for power supply from the AC power source 11 is shown by one line and three diagonal lines are attached to indicate that it is a three-phase wiring. Further, the control circuit 108 of the die cushion motor power conversion device 121 has the same configuration as the position speed current control circuit 16 (see FIG. 10) shown in the first embodiment, and has the same configuration as the stored energy calculation circuit 14. It does not have the function as. A motor drive command is given to the control circuit 108 of the die cushion motor power conversion device 121 (AC input) from the host device 13, and the operation mode of the die cushion motor 103 is set to the upper die during the drawing period. Since the blank material is sandwiched between the mold and the lower mold, a reaction force is applied by torque control. This torque control gives the same torque as the reaction force when the pneumatic die cushion device 31 is used. It is operated by position control or speed control except during the drawing period.

FIG. 21 is a diagram schematically illustrating the structure of the press machine with a servo die cushion according to the present embodiment.

In FIG. 21, in the press machine 12A with a servo die cushion, the pneumatic die cushion device 31 is a servo die cushion device as compared with the press machine 12 with a pneumatic die cushion shown in the first embodiment (see FIG. 3). It is changed to 32, and also has a die cushion motor 103 for driving the servo die cushion device 32.

Other configurations are the same as those in the first embodiment.

A fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, only the differences from the third embodiment will be described, and in the drawings used in this embodiment, the same members as those in the third embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, the power supply of the servo die cushion device 32 in the press machine 12A with the servo die cushion of the third embodiment is supplied from the input of the buck-boost power supply circuit 5 (in other words, the output of the forward converter 4). It was done.

FIG. 22 is a diagram schematically showing an example of the power conversion system according to the present embodiment.

In FIG. 22, the input power source of the die cushion motor power conversion device 121A (DC input) is connected between P0 and P0 on the input side of the buck-boost power supply circuit 5 of the power supply device 1. That is, the die cushion motor power converter 121A (DC input) is a DC power supply input because it is connected to the output of the forward converter 4, and the motor power conversion circuit 107A does not need to function as a forward converter. be.

Other configurations are the same as those in the third embodiment.

Since the motor 3 (hereinafter, also referred to as the slide motor 3) and the die cushion motor 103 generate torque in the pushing direction against each other during drawing and cutting, the die cushion motor 103 is operated in the power running direction when the slide motor 3 is operated in the power running direction. Will be regenerative operation. On the contrary, when the slide motor 3 is operated in the regenerative direction, the die cushion motor 103 is in power running operation. For example, when the slide motor 3 is operated by power running, it is when the power supply 11 side is desired to be supplied. At this time, the die cushion motor 103 is regenerative and the power supplied from the power supply is surplus. Become. Since the die cushion motor power converter 121A (DC input) does not have a function as a buck-boost power supply circuit, the voltage level is the same as that of the slide motor 3, so that both are forward converters 4 of the power supply device 1. Can be connected to. In this state, the regenerative power of the die cushion motor 103 can be boosted and supplied as power running power of the slide motor 3 in the buck-boost power supply circuit 5, so that the power supply from the power supply 11 side is suppressed or eliminated. It is possible to achieve energy saving.

On the contrary, if the slide motor 3 is regenerated, the voltage of the accumulator 6 predicts the regenerative state and the voltage is already in the lowered state, so that the regeneration starts from that voltage. At this time, since the die cushion motor 103 is power running, electric power can be supplied from the power supply 11 side, and power is not supplied from both of them.

As described above, since power running and regeneration are switched in a well-balanced manner during drawing and cutting, the voltage between the DC voltage P0 and N of the power supply device 1 is kept substantially constant regardless of which is in the regenerative state. Therefore, there is an effect that there is no problem even if the elastic load storage energy calculation circuit 46 is operated in an invalid state, that is, the clear signal CLR2 is turned ON. Since the slide motor 3 stores energy in the inertial load at the end of drawing and cutting, the inertial load storage energy calculation circuit 44 needs to be operated as valid (clear signal CLR1 is OFF).

A fifth embodiment of the present invention will be described with reference to FIG. In this embodiment, only the differences from the first embodiment will be described, and in the drawings used in this embodiment, the same members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

This embodiment exemplifies a case where a lifting device is used as a load and driven by a motor.

FIG. 23 is a diagram schematically showing an example of the power conversion system according to the present embodiment.

In this example,
In FIG. 23, the elevating device 82 of this embodiment includes a hoisting machine 76 (see FIG. 5). The elevating device 82 is a load that is the easiest to explain the regenerative state as a gravity load. As the lifting load of this embodiment, an elevator with a large height difference in the direction of gravity is not assumed, a lifting device for cars and luggage in the floor, a lifting device for storage parts between upper and lower shelves, and parts for transporting up and down in the device. It is supposed to be transported. When the luggage 77 rises, the motor 3 operates in a power running state because of the operation in the direction opposite to gravity, and when descending, the motor 3 descends while suppressing the fall, so that the motor 3 is in a regenerative state.

Further, in FIG. 23, in the stored energy calculation circuit 14B (calculation circuit), the elastic load storage energy calculation block 41 is the gravity load storage energy as compared with the storage energy calculation circuit 14 (see FIG. 7) of the first embodiment. It has been replaced by the arithmetic block 79. Further, the gravity load storage energy calculation block 79 has a gravity load power calculation circuit 80 and a gravity load storage energy calculation circuit 81. However, the gravity load torque Tw is Tq-Tα as described in the above (Equation 12), the gravity load power Pw is calculated by the gravity load power calculation circuit 80, and the gravity load storage energy Ew is calculated by the gravity load storage energy calculation circuit 81. Is calculated.

The output Eα of the inertial load storage energy calculation block 40 and the output Ew of the gravity load storage energy calculation block 79 are added by the addition calculator 50, and the total load storage energy E is output to the voltage command calculation circuit 15 of the power supply device 1.

Other configurations are the same as those in the first embodiment.

Also in this embodiment configured as described above, the voltage command Vref of the storage device 6 shown in the above (Equation 17) can be obtained as in the first embodiment.

A sixth embodiment of the present invention will be described with reference to FIG. 24. In this embodiment, only the differences from the first embodiment will be described, and in the drawings used in the present embodiment, the same members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, the motor is composed of a linear motor and an encoder.

FIG. 24 is a diagram schematically showing an example of the power conversion system according to the present embodiment.

In FIG. 24, the motor 3C is composed of a linear motor 9C and a position detector (linear encoder, Hall sensor) 10C for acquiring the position of the linear motor 9C.

The physical quantity related to the linear motor 9C of this embodiment and the physical quantity related to the AC motor 9 shown in the first embodiment correspond to each other as follows. That is, the speed v (m / s), the moment of inertia Fq (N), the mass M (kg), and (1/2) Mv ^ 2 in the linear motor 9C are the AC motor 9 (that is, the rotary servo motor). It corresponds to the angular velocity ω (rad / s), the torque Tq (N · m), the moment of inertia J (kg · m ^ 2), and the inertial load energy (1/2) Jω ^ 2, respectively.

Further, the inertial load power Pα, the traveling power Pd, the inertial load energy Eα, and the traveling energy Ed (corresponding to the above (formula 3) to (formula 6) in the case of the AC motor 9) in the linear motor 9C are as follows. It is represented by (Equation 24) to (Equation 27), respectively.

In the above (Equation 25), the traveling speed v (m / s) = dl / dt and the constant thrust Fq (N).

That is, in FIG. 24, in the stored energy calculation circuit 14C (calculation circuit), the acceleration / deceleration torque calculation circuit 42 related to the moment of inertia J is compared with the storage energy calculation circuit 14 (see FIG. 7) of the first embodiment. It has been replaced by the acceleration / deceleration torque calculation circuit 142 related to the mass M, and the position / speed current control circuit 16C outputs the mass M to the acceleration / deceleration torque calculation circuit 142 and outputs the moment of inertia Fq instead of the motor load torque Tq. It is configured as follows.

Other configurations are the same as those in the first embodiment.

As described above, even when a linear motor is used, it can be controlled in the same manner as in the first embodiment.

<Additional Notes>
The present invention is not limited to the above embodiment, and includes various modifications and combinations within a range not deviating from the gist thereof. Further, the present invention is not limited to the one including all the configurations described in the above-described embodiment, and includes the one in which a part of the configurations is deleted. Further, each of the above configurations, functions and the like may be realized by designing a part or all of them by, for example, an integrated circuit. Further, each of the above configurations, functions, and the like may be realized by software by the processor interpreting and executing a program that realizes each function.

1 ... power supply device, 2, 2A ... motor power conversion device (power conversion device), 3 ... motor, 3C ... linear motor, 4 ... forward converter, 5 ... buck-boost power supply circuit (boost-boosting power supply circuit, step-down power supply circuit), 6 ... Power storage device, 6A ... Power storage element, 7 ... Reverse converter (power conversion unit), 8,108 ... Control circuit (control unit), 9 ... AC motor, 9C ... AC motor (linear motor), 10 ... Encoder, 10C ... Position detector (linear encoder, Hall sensor), 11 ... AC power supply, 12 ... Press machine with pneumatic die cushion, 12A ... Press machine with servo die cushion, 13 ... Upper device, 14, 14A, 14B, 14C ... Stored energy calculation circuit (calculation circuit), 15 ... voltage command calculation circuit, 16, 16A ... position / speed current control circuit, 17 ... controller, 18 ... insulation amplifier, 20 ... slide motor, 21 ... slide drive means, 22 ... crank Shaft, 23 ... Crank eccentric part, 24 ... Connection rod, 25 ... Slide, 26 ... Slide give, 27 ... Bolster, 28 ... Bed, 29 ... Upper mold, 30 ... Lower mold, 31 ... Pneumatic die cushion device, 32 ... Servo die cushion device, 34 ... Injection shaft, 35 ... Injection molding machine, 40 ... Inertial load storage energy calculation block, 41 ... Elastic load storage energy calculation block, 42, 142 ... Acceleration / deceleration torque calculation circuit, 43 ... Acceleration / deceleration Power calculation circuit, 44 ... Inertial load storage energy calculation circuit, 45 ... Elastic load power calculation circuit, 46 ... Elastic load storage energy calculation circuit, 47 ... Energy setting block when fully charged, 48 ... Proportional coefficient block, 49 ... Square root calculation circuit , 50 ... Addition calculator, 51 ... Addition / subtraction calculator, 52 ... Smoothing capacitor, 53 ... Switching element, 54 ... Diode, 55 ... Full-wave rectifier, 56 ... Resistor, 58 ... Boost reactor, 58A ... Step-down reactor, 59 ... U-phase current detector (current detector), 60 ... W-phase current detector (current detector), 61 ... drive circuit, 62 ... position speed pole position calculation circuit, 63 ... speed control circuit (ASR), 64 ... axis Current control circuit (ACR), 65 ... Shaft current control circuit (ACR), 66 ... Phase conversion circuit, 67 ... Circuit, 68 ... Conversion circuit, 73, 74 ... Mode selector switch, 75 ... Parameter area, 76 ... Winder, 77 ... Luggage (or a basket for accommodating luggage), 78 ... Rope, 79 ... Gravity load storage energy calculation block, 80 ... Gravity load power calculation circuit, 81 ... Gravity load storage energy calculation circuit, 82 ... Elevating device, 103 … Die cushion motor, 107, 107A… Motor power conversion circuit, 109 ... AC motor, 110 ... Encoder, 120 ... Motor load, 121, 121A ... Die cushion motor power conversion device

Claims (8)

A power converter that supplies power to the motor and
In a power conversion system including a power supply device that supplies power to the power conversion device,
The power converter is
It has a power conversion unit that converts the power supplied from the power supply device, a control unit that controls the power conversion unit, and a current detection unit that detects the current in the power conversion unit.
The power supply device
A storage device that stores electric power according to the voltage, a buck-boost power supply circuit that changes the voltage of the storage device based on a voltage command, and a buck-boost power supply that calculates the energy stored in the storage device as the voltage command. It has an arithmetic circuit that outputs to the circuit,
The control unit calculates the angular velocity and torque of the motor using the information from the encoder included in the motor and the current value detected by the current detection unit, and the calculated angular velocity and torque and the preset moment of inertia. The power running energy or regenerative energy of the motor is calculated using the value and
In the arithmetic circuit, the amount of electric power stored in the storage device based on the power running energy or regenerative energy of the motor calculated by using the current value supplied to the motor by the control unit is the maximum electric energy by the regenerative energy. A power conversion system that calculates the energy stored in the storage device so as to be . In the power conversion system according to claim 1,
The control unit is a power conversion system that calculates the regenerative energy based on the inertial energy stored in the motor and the elastic energy stored in the motor load driven by the motor. In the power conversion system according to claim 1,
The control unit is a power conversion system that calculates the regenerative energy based on the inertial energy stored in the motor load driven by the motor and the gravitational energy stored in the motor load. In the power conversion system according to claim 1,
The moment of inertia value is stored in the power conversion system during the trial run of the motor or the real-time auto-tuning. The procedure for converting the electric power supplied through the storage device that stores electric power and supplying it to the motor,
A procedure for calculating the angular velocity and torque of the motor using the information from the encoder provided in the motor and the current value supplied to the motor, and
A procedure for calculating the power running energy or regenerative energy of the motor using the calculated angular velocity and torque and a preset moment of inertia value, and
The amount of electric power stored in the storage device based on the power running energy or the regenerative energy of the motor calculated by using the current value supplied to the motor is stored in the storage device so as to be the maximum electric energy by the regenerative energy. The procedure for calculating the energy to be used and
A motor control method comprising a procedure for changing the electric power stored in the storage device based on a calculation result of energy stored in the storage device. In the motor control method according to claim 5 ,
A motor control method comprising calculating the regenerative energy based on the inertial energy stored in the motor and the elastic energy stored in the motor load driven by the motor. In the motor control method according to claim 5 ,
A motor control method comprising calculating the regenerative energy based on the inertial energy stored in the motor load driven by the motor and the gravitational energy stored in the motor load. In the motor control method according to claim 5 ,
A motor control method characterized in that the moment of inertia value is stored during a trial run of the motor or during real-time auto-tuning.

Images