JP5442245B2 - Overload protection method and apparatus for common converter, and multi-axis motor drive system - Google Patents

Description

The present invention relates to a multi-axis motor drive system for driving the industrial machine tool having a plurality of servo motors, in particular, multi-axis motor drive system commonly used as a source of direct current to the servo amplifier for driving the servo motor The present invention relates to an overload protection method and apparatus for a common converter, and a multi-axis motor drive system .

  Conventionally, as a motor drive system for industrial machine tools and the like, a system that converts the torque of a small-medium-capacity servo motor into a large torque using a gear has been used, but in recent years, a gear that is complicated and difficult to maintain. As an example of this, direct drive that does not use is progressing. For example, a plurality of servo motors are provided in a machine to be driven such as an industrial machine tool, and each servo motor shares the drive location of each part of the machine to be driven. There have been proposed multi-axis motor drive systems that are driven in this manner.

  FIG. 7 is a system configuration diagram showing an example of such a multi-axis motor drive system, in which 1 is an AC power source, 2 is a common converter, 3a, 3b and 3c are servo amplifiers, 4a, 4b and 4c are servo motors, 5a, Reference numerals 5b and 5c denote position sensors.

  In the figure, the drive target machine uses a plurality (here, three) of servo motors 4a to 4c, and each servo motor 4a to 4c is driven by a servo amplifier 3a to 3c, respectively. As these DC power supplies, the same single converter, that is, the common converter 2 is used.

  The alternating current from the alternating current power source 1 is converted into direct current by the common converter 2 and supplied to the servo amplifiers 3a to 3c. Each of the servo amplifiers 3a to 3c includes an inverter, and the supplied direct current is converted into alternating current by the inverter and supplied to the servo motors 4a to 4c.

  Each of the servo motors 4a to 4c is provided with position sensors 5a to 5c for detecting the rotation amount, and the detection outputs thereof are supplied to the servo amplifiers 3a to 3c. When a position command value for instructing the rotation amount of the servo motors 4a to 4c is supplied to the servo amplifiers 3a to 3c, the inverter unit of the servo amplifiers 3a to 3c operates to supply a drive current to the servo motors 4a to 4c. The servo motors 4a to 4c are rotationally driven. At this time, the rotation amounts of the servo motors 4a to 4c are monitored by the detection outputs of the position sensors 5a to 5c, and the inverter is controlled. As a result, the servo motors 4a to 4c rotate by the rotation amount corresponding to the position command value. Driven.

  The above is the description of the position control. In the case of speed control and torque control, the rotational drive is similarly performed at the speed and torque corresponding to the speed command value and torque command value.

  By the way, one common converter 2 is commonly used for the servo amplifiers 3a to 3c, and this common converter 2 bears the load of the servo amplifiers 3a to 3c. The converter load increases and the amount of heat generation increases. The common converter 2 is also provided with a normal heat dissipation mechanism so that an abnormal temperature rise can be suppressed. However, when the overheated state causes a heat generation state that cannot be dissipated by this heat dissipation mechanism, the common converter A failure may occur and the multi-axis motor drive system may become inoperable.

  In order to prevent this, the outputs of the respective servo amplifiers 4a to 4c are obtained and added, and the average value per one period of the multi-axis operation of the added output is compared with a threshold value (rated output of the converter 2). Thus, when the average value exceeds the threshold value, it is assumed that the common converter 2 is in an overload state, and the outputs from all the servo amplifiers 3a to 3a are stopped, or a predetermined one of the servo motors 4a to 4c is selected. There has been proposed a technique in which the operation speed of the apparatus is reduced (for example, see Patent Document 1).

JP 2002-199792 A

  By the way, when the servo amplifiers 3a to 3c are simultaneously overloaded, a very large current instantaneously flows in the common converter, and abnormal heat generation is instantaneously generated, which causes a failure of the common converter. It may become.

  On the other hand, in the technique described in Patent Document 1, an overload state is detected by comparing the average value of one operation cycle of the sum of output powers of the servo amplifiers 3a to 3c with a threshold value. The above instantaneous overcurrent (hereinafter referred to as overload current) due to overload cannot be detected, and the common converter cannot be protected against such an overload condition.

  In order to protect against such an instantaneous excessive current, it is conceivable to increase the capacity of the common converter or provide a circuit for detecting the output voltage and output current in the common converter. However, there is a problem that the cost and size of the common converter increase.

An object of the present invention, this problem is overcome, multi-axis which is adapted to avoid an increase in cost and size of the common converter, can also protect the common converter for such instantaneous overcurrent common converter overload protection method and apparatus for a motor drive system, and to provide a multi-axis motor drive system.

In order to achieve the above object, the first means of the present invention is a multiple converter that converts alternating current to direct current with a common converter and supplies it to a plurality of servo amplifiers, and drives a servo motor for each of the plurality of servo amplifiers. In the overload protection method of the common converter of the shaft motor drive system, the supplement to complement the overload judgment value corresponding to the total consumption current by calculating the consumption current for each servo amplifier and adding these consumption currents the value for the overload determination value determined by adding the previous overload judgment value used in the previous overload determination by comparing a threshold value corresponding to the capacitance of a preset common converter, is the common converter If it is determined whether or not the common converter is in an overload state as a result of determining whether or not it is in an overload state, the operations of all the servo amplifiers are stopped. It is characterized in.

According to a second means of the present invention, there is provided a common converter for a multi-axis motor drive system that converts alternating current into direct current with a single common converter and supplies it to a plurality of servo amplifiers, and drives a servo motor for each of the plurality of servo amplifiers. In the overload protection method, the current consumption for each servo amplifier is obtained, and the supplementary value for complementing the overload judgment value corresponding to the total current consumption obtained by adding these current consumptions is used as the previous overload judgment. in the overload determination value determined by adding the previous overload judgment value used, by comparing the threshold value according to the capacity of the preset common converter, whether the common converter is overloaded As a result, when it is determined that the common converter is in an overload state, there is a servo amplifier that can reduce the output by a predetermined amount from the plurality of servo amplifiers. If the output of the servo amplifier to reduce the predetermined amount, and wherein the stopping the plurality of servo amplifiers all operating Without.

According to a third means of the present invention , in the first means or the second means, the torque value of the servo motor, the speed detection of the servo motor, the direct current DC voltage detection value supplied from the common converter to the plurality of servo amplifiers, The current consumption is obtained from the above.

A fourth means of the present invention, in any one of the means in the first means to third means, when comprehensive supply current is a negative value, the overload determination by the overall current consumption to zero It is characterized by obtaining a value.

Fifth means of the present invention, in the fourth means, the overload judgment value, the total current consumption is increased temperatures also common converter into a complementary value corresponding to the temperature drop, the determine value previously obtained those wherein adding the complementary value or may be equal to a value obtained by subtracting.

According to a sixth aspect of the present invention, there is provided a common converter of a multi-axis motor drive system that converts alternating current to direct current with a single common converter, supplies the direct current to a plurality of servo amplifiers, and drives a servo motor for each of the plurality of servo amplifiers. In the overload protection device, a first computing means for obtaining a consumption current for each of the plurality of servo amplifiers and a second computing means for obtaining a total consumption current by adding the consumption currents of the plurality of servo amplifiers obtained by the first computing means. For the overload determination value obtained in addition to the previous overload determination value used in the previous overload determination, a complementary value for complementing the overload determination value corresponding to the total current consumption is calculated in advance. Compared with the threshold value according to the set capacity of the common converter, the third converter for determining whether or not the common converter is in an overload state, and the common converter is overloaded by the third calculator. Characterized in that and an operation control means for stopping the plurality of servo amplifiers all operation when it is determined that the state.

According to a seventh aspect of the present invention, there is provided a common converter for a multi-axis motor drive system that converts alternating current to direct current with a single common converter and supplies it to a plurality of servo amplifiers, and drives a servo motor for each of the plurality of servo amplifiers. In the overload protection device, a first computing means for obtaining a consumption current for each of the plurality of servo amplifiers and a second computing means for obtaining a total consumption current by adding the consumption currents of the plurality of servo amplifiers obtained by the first computing means. For the overload determination value obtained in addition to the previous overload determination value used in the previous overload determination, a complementary value for complementing the overload determination value corresponding to the total current consumption is calculated in advance. Compared with the threshold value according to the set capacity of the common converter, the third converter for determining whether or not the common converter is in an overload state, and the common converter is overloaded by the third calculator. If there is a servo amplifier that can reduce the output by a predetermined amount among the plurality of servo amplifiers when it is determined that the servo amplifier is in the state, the output of the servo amplifier is reduced by the predetermined amount. And an operation control means for stopping the operation.

According to an eighth means of the present invention , in the sixth means or the seventh means , the first calculation means is supplied to a plurality of servo amplifiers from a servo motor torque value, servo motor speed detection, and a common converter. The current consumption is obtained from a DC voltage detection value of DC.

Ninth means of the present invention, in any one unit means the sixth means to eighth, third computing means, overall current consumption obtained by the second calculating means is negative when, and obtaining the overload judgment value the overall current consumption as zero.

Tenth means of the invention, in the ninth means, third computing means, the overall current consumption common converter temperature rise or the converted into complementary value corresponding to the temperature drop, determine value previously obtained also adds those the complement value and obtains the subtraction to the overload determination value.

11 means of the present invention, a plurality of servo amplifiers for driving a plurality of servo motors, respectively, and a common converter supplies simultaneously on multiple servo amplifier to convert the ac to dc, the sixth characterized in that it is a multi-axis motor drive system and a overload protection device common converter of any one means of means, second 10 means.

According to the present invention, the current consumption for each servo amplifier is obtained, and the complementary value for complementing the overload determination value corresponding to the total current consumption obtained by adding these current consumptions is used in the previous overload determination. for the overload determination value determined by adding the previous overload judgment value, by comparing with a threshold value corresponding to the capacitance of a preset common converter, in order to determine whether common converter is overloaded In addition to overload conditions caused by a continuous increase in load current of the common converter, overload conditions caused by an instantaneous increase in overload current can be detected, and each servo amplifier can be operated during such overload. The common converter can be reliably protected by controlling.

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

  First, referring to FIG. 2, a schematic configuration of an overload protection device for a multi-axis motor drive system and its common converter according to the present invention will be described. However, in FIG. 2, 10a, 10b, and 10c are consumption current calculation units, and 20 is an overload detection unit, and parts corresponding to those in FIG.

  The multi-axis motor drive system in which the overload protection device for a common converter according to the present invention is used also has the same system configuration as that of FIG.

  In FIG. 2, servo amplifiers 3a, 3b, and 3c are provided with consumption current calculation units 10a, 10b, and 10c, respectively, constituting an overload protection device for a common converter according to the present invention, and a servo amplifier 3a as a master amplifier. Further, an overload detection unit 20 constituting the overload protection device for the common converter according to the present invention is provided. In contrast, the servo amplifiers 3b and 3c are slave amplifiers.

  The consumption current calculation units 10a, 10b, and 10c detect consumption currents Iia, Iib, and Iic in the servo amplifiers 3a, 3b, and 3c, respectively, and these are supplied to the overload detection unit 20 in the servo amplifier 3a to instantaneously Or continuous overload current is detected instantaneously. Here, instantaneously detected overload current means that even if excessive overload current occurs instantaneously or continuously, it will occur and be detected instantaneously. In the following description, it is assumed that an instantaneous overload current is detected, but the same applies to the case where the overload current is continuously detected.

  Further, the detection of the overload current is repeatedly performed at a predetermined cycle.

  FIG. 1 is a block diagram showing a first embodiment of an overload protection method and apparatus for a common converter of a multi-axis motor drive system and a multi-axis motor drive system according to the present invention, wherein 21 is a converter output current calculation unit, 22 is a time limit calculation unit, 23 is an overload determination unit, 30 is an inverter, 31 is a current detection unit, 32 is a current control calculation unit, 33 is a position control calculation unit, 34 is a speed calculation unit, 35 is a speed control calculation unit, Reference numeral 36 denotes a voltage detection unit, and reference numeral 40 denotes a display unit. Parts corresponding to those in FIGS. Hereinafter, the servo amplifier 3a of the master amplifier will be described.

  In the figure, the servo amplifier 3a is provided with an inverter 30, and the direct current from the common converter 2 (FIG. 7) is converted into an alternating current by the inverter 30 and supplied to the servo motor 4a as a drive current. The drive current is detected by the current detection unit 31, and the detected current value of the detection result is supplied to the current control calculation unit 32.

On the other hand, the detection output (rotation amount) of the position sensor 5a of the servo motor 4a is supplied to the speed calculation unit 34 and processed to detect the rotation speed when the servo motor 4a is rotating, and the speed detection value. It is output as ω _i a and supplied to the position control calculation unit 33. In the position control calculation unit 33, when a position command value is supplied from the outside, a speed command value for rotating the servo motor 4a to a position corresponding to the position command value based on the detection output of the position sensor 5a. Is generated and output. The speed command value is supplied to the speed control calculation unit 35 together with the speed detection value ω _i a from the speed calculation unit 34, and a current command value I for rotating the servo motor 4a at a speed corresponding to the speed command value. _i ^* a is generated. The current command value I _i ^* a is supplied to the current control calculation unit 32, and based on the detected current value from the current detection unit 31, the drive current supplied from the inverter 30 to the servo motor 4 a is the current command value I _i. ^* A control signal for controlling the inverter 30 is generated so as to be a.

When there is a position command value from the outside, the servo motor 4a is in a stopped state, and when the detected current value from the current detector 31 and the detection output of the position sensor 5a are zero, a current command corresponding to this position command value The value I _i ^* a is output from the speed control unit 35 and supplied to the current control calculation unit 32, whereby the drive current corresponding to the current command value I _i ^* a is supplied from the inverter 30 to the servo motor 4a. Thus, the inverter 30 is controlled. As a result, the inverter 30 controls the ON / OFF timing of the switching element to output a current, which supplies a drive current to the servo motor 4a. Along with the supply of the drive current, torque is generated in the servo motor 4a, whereby the servo motor 4a is started. The servo motor 4a is accelerated, and when the speed reaches a specified speed, the servo motor 4a rotates at the specified speed.

  Note that during the period of accelerating the servo motor 4a to a specified speed, electric power is supplied from the common converter 2 via the servo amplifier 3a, which is called power running.

Further, when the servo motor 4a rotates a predetermined amount in accordance with the position command value from the outside, the rotation sensor 5a detects this, so that the current command value I _i ^* a output from the speed control calculation unit 35 is zero. Thus, the servo motor 4a stops. The servo motor 4a is stopped when the servo motor 4a is gradually decelerated. As a result, a voltage is induced in the stator coil of the servo motor 4a, and the electric power generated thereby is transmitted through the servo amplifier 3a. Returned to the common converter 2.

  In this way, when the servo motor 4a decelerates in this way, electric power is returned to the converter 2 is called regeneration.

Also, assuming that the rotation direction of the servo motor 4a in the above case is a positive rotation direction, if the position command value at this time is a positive position command value, a negative position command value is supplied from the outside. Then, a negative current command value I _i ^* a is output from the speed control calculation unit 35 and supplied to the current control calculation unit 32. Thereby, the current control calculation unit 32 controls the inverter 30 so that the servo motor 4a rotates in the negative rotation direction. Also in this case, the servo motor 4a is started and accelerated in the negative rotation direction, and the acceleration period becomes a power running section, and the deceleration period when the servo motor 4a stops thereafter becomes a regeneration section.

  FIG. 3A shows a power running section and a regeneration section with respect to the positive and negative rotation directions of the servo motor 4a. The horizontal axis represents the time axis, and the vertical axis represents the torque value T and the detected speed value ω. The positive region on the vertical axis is the positive rotation direction, and the negative region is the negative rotation direction.

The torque value T is determined by the current command value I _i ^* a, where K _t is the torque constant.
T _i = K _t × I _i ^* a (1)
The detection speed value ω is a speed detection value of the speed calculation unit 34.

  In FIG. 3A, when the servo motor 4a is started to rotate in the positive rotation direction, the torque value T in the power running section is positive, and the speed detection value ω is also increased to a positive value. Go. When the servo motor 4a is started to rotate in the negative rotation direction, the torque value T in the power running section is negative, and the speed detection value ω is also increased as a negative value.

  On the other hand, when the servo motor 4a rotating in the positive rotation direction stops, the torque value T in the regeneration section is negative, and the speed detection value ω decreases with a positive value. When the servo motor 4a rotating in the negative rotation direction stops, the torque value T in the regeneration section is positive, and the speed detection value ω decreases with a negative value.

  As described above, the servo motor 4a is controlled, but the same applies to the other servo motors 4b and 4c and the servo amplifiers 3b and 3c.

  Next, the overload protection method and apparatus for the common converter of the multi-axis motor drive system of the first embodiment will be described.

The overload protection device for this common converter
In the consumption current I _i calculation unit 10a in the servo amplifier 3a, the current command value I _i ^* a output from the speed control calculation unit 35, the speed detection value ω _i a output from the speed control unit 34, and the voltage detection The DC voltage detection value V _dci a supplied from the common converter 2 detected by the unit 36 is taken in at a predetermined cycle.

This period is sufficiently shorter than the time length (for example, several tens of msec or more) of the power running section and the regeneration section in FIG. 3A, and is a period of several tens of μsec to msec. The current command value I _i ^* a and speed detection Each time the value ω _i a and the DC voltage detection value V _dci a are _fetched , the following processing operation is performed to determine overload of the common converter 2.

Therefore, when the current command value I _i ^* a, the speed detection value ω _i a, and the DC voltage detection value V _dci a are taken in the current consumption I _i calculation unit 10a, first, a preset torque constant K _t is set. From the a and current command value I _i ^* a, the torque value T _i a of the servo motor 4a is calculated according to the above equation (1).
T _i a = K _t a × I _i ^* a (2)
Next, the output value P _i a to the servo motor 4a is obtained from the torque value T _i a and the speed detection value ω _i a described above.
P _i a = T _i a × ω _i a (3)
Ask for. Further, the consumption current value I _i a of the servo amplifier 3a is calculated from the output value P _i a and the DC voltage detection value V _dci a described above.
I _i a = P _i a / V _dci a (4)
Ask for.

Here, FIG. 3B is a diagram showing the output value P _i and the current consumption value I _i with respect to FIG. 3B. In the power running section, both the torque value P _i and the detected speed value ω _i are both. Since it is a value in the rotation direction of the servo motor 4a, the output value P _i and the current consumption value I _i increase with values according to the rotation direction of the servo motor 4a and are positive values. Both the torque value P _i and the speed detection value ω _i are values opposite to the rotation direction of the servo motor 4a. Therefore, the output value P _i and the current consumption value I _i are different from the rotation direction of the servo motor 4a. continue to decrease in value corresponding to the opposite direction, current consumption value I _i a servo amplifier 3a obtained in this manner is a negative value is supplied to the converter output current computing unit 21 of the overload detection section 20 However, in the servo amplifiers 3b and 3c, the current consumption calculators 10b and 10c are also provided. Its current consumption value (Figure _{2) I i b, I i} c are detected, these current consumption value I _i b, I _i c is supplied to the converter output current computing unit 21.

Converter output current calculating unit 21, these current consumption value I _i a, I _i b, total current consumption value I _CVO of I _i c, i.e.,
I _cvo = ΣI _i (5)
Ask for. The total consumption current value I _cvo relates to the output current value of the common converter 2. However, these current consumption value _{I i a, I i b,} I i c , regardless of the direction of rotation of the positive and negative servo motor 4 a to 4 c, as described above, in the power running period is a positive value, regeneration segment Then, it is a negative value. Therefore, when the total consumption current value I _cvo <0, at least one of the servo motors _{4a to 4c} is in the regeneration section and power is returned to the common converter 2. In this case, the common converter 2 In this case, heat generation is not performed and heat dissipation is dominant, so that it is not necessary to perform the protection operation. Therefore, when the total consumption current value I _cvo <0, the total consumption current value I _cvo = 0. The total consumption current value I _cvo obtained in this way is supplied to the time limit calculation unit 22 of the overload detection unit 20.

The timed operation unit 22, a data table is set in the complementary value f corresponding to the total current consumption value _I cvo (I cvo), complementary value f (I corresponding from the data table in this complex current consumption value I _{CVO cvo} ) is extracted, and an overload determination value, that is, an overload determination value I _s (k) is obtained according to the following equation (6).

I _s (k) = I _s (k−1) + f (I _cvo ) (6)
However, I _s (k−1) is the previous overload determination value used in the previous overload determination.

If there is no complementary value f (I _cvo ) corresponding to the total current consumption value I _cvo in the data table, the complementary value f (I _cvo of the total current consumption value I _cvo on both sides of the total current consumption value I _cvo is _present. ) Can be extracted and obtained by these interpolation processes.

Here, in the previous determination of the overload determination value I _s (k−1), the current corresponding to the total consumption current value is output from the common converter 2 and the common converter 2 is in a state of generating heat. As a result, the common converter 2 is heated to a certain temperature, and when the current of the total consumption current value I _cvo is output from the common converter 2 at the next (current) overload determination, Due to the heat generated by this, the common converter is heated, and the temperature of the common converter 2 changes from the previous temperature by the amount of heat generated by the current total current consumption value I _cvo .

The above equation (6) represents this, and I _s (k−1) is a current value corresponding to the heating temperature of the common converter 2 at the time of the previous overload determination, and + f (I _cvo ) Is a current value corresponding to a change in the heating temperature from the heating temperature of the common converter 2 at the time of the previous overload determination at the time of the current overload determination.

When the total consumption current value I _cvo at the time of the current overload determination is an increase over the total consumption current value at the time of the previous overload determination and the heating temperature of the common converter 2 is increased ( If the calorific value of common converter 2 by total current consumption value I _CVO are above the heat radiation amount) in the above formula (6), complementary value f (I _CVO) is a positive value, the previous overload judgment value I _s (k−1) is added to “+ f (I _cvo )”, and the total current consumption value I _cvo at the time of the current overload determination has decreased with respect to the total current consumption value at the time of the previous overload determination. When the heating temperature of the common converter 2 is _lowered (when the heat generation amount of the common converter 2 by the total consumption current value I _cvo is less than the heat dissipation amount), the complementary value f in the above equation (6) (I _CVO) is a negative value, the previous overload judgment value I _s ( Added to -1).

Thus, for total current consumption value I _CVO, common heating temperature rises converter 2, to indicate that the drops, complementary value f corresponding overall current consumption value I _CVO the vertical movement of the heating temperature By converting to (I _cvo ), the overload determination value I _s (k) is obtained by the above equation (6).

FIG. 4 is a graph schematically showing the relationship between the total consumption current value I _cvo and the complementary value f (I _cvo ).

In the figure, as described above, when the total consumption current value I _cvo ≧ 0 and the total consumption current value I _cvo when the heat generation and the heat dissipation are balanced in the common converter 2 is the equilibrium point I _ep ,
When I _ep ≧ I _cvo ≧ 0, the complementary value f (I _cvo ) ≦ 0
The overload determination value I _s (k) is equal to or lower than the overload determination value I _s (k−1) at the previous overload determination. This is a case where the total consumption current value I _cvo is smaller than I _ep even in the regeneration section and the power running section in FIG.

When I _cvo > I _ep , the complementary value f (I _cvo )> 0
Thus, the overload determination value I _s (k) is higher than the overload determination value I _s (k−1) at the previous overload determination. This is a power running section in FIG. _3A and is a case where the increase in the total consumption current value I _cvo is large.

Returning to FIG. 1, the overload determination value I _s (k) obtained by the time calculation unit 22 is supplied to the overload determination unit 23. In the overload determination unit 23, the determination threshold value I _th in accordance with the capacitance of the common converter 2 common converter 2 overload judgment value I _s at which the overload state (k) is used is set in advance The overload determination value I _s (k) obtained by the time calculation unit 22 is compared with the determination threshold value I _th . And
I _s (k) <I _th
Is determined that the common converter 2 is not overloaded, and
I _s (k) ≧ I _th
In this case, it is determined that the common converter 2 is in an overload state, this is notified to the display unit 40 and an alarm is generated, and this is also notified to a control unit (not shown) to perform predetermined control described later. To do.

  FIG. 5 is a flowchart showing a specific example of the processing operation of the first embodiment. Hereinafter, this specific example will be described with reference to FIG.

Determination threshold I _th for each common converter capacity in a memory (not shown) is different in FIG. 1 is stored, it is read out determination threshold I _th of the volume of the common converter 2 used in Fig. 1 the overload determination unit 23 (Step S100).

In the consumption current I _i calculation unit 10 a, the current command value I _i ^* a from the speed control calculation unit 35, the detected speed value ω _i a from the speed calculation unit 34, and the DC voltage detection value V _dci a from the voltage detection unit 36. When taken in, the consumption current I _i calculation unit 10a obtains the consumption current value I _i a based on the above formulas (2) to (4), and the servo amplifier obtained in the same manner. 3b, current consumption value I _i b from 3c, and a I _i c, the converter output current calculating unit 21, according to the above equation (5), the total current consumption value I _CVO is determined (step S101).

Next, the time calculation unit 22 _obtains a complementary value f (I _cvo ) corresponding to the total consumption current value I _cvo from the data table (step S102), and the overload determination value I _s ( k) is obtained (step S103).

Then, the overload determination unit 23 compares the overload determination value I _s (k) with the predetermined determination threshold value I _th in step S100, and when I _s (k) <I _th (in step S4). “Yes”), the operation of the multi-axis motor drive system is continued as it is (step S105), and the next current command value I _i ^* a, speed detection value ω _i a, DC voltage detection value V _dci a is taken in step S101. The processing operation from is repeated.

When I _s (k) ≧ I _th (“No” in step S104), the control unit (not shown) is operated to stop the operations of the servo amplifiers 3a to 3c (step S106), and the display unit 40 is notified that the common converter 2 is in an overload state, and an overload alarm is generated (step S107).

  As a result, the multi-axis motor drive system stops and the common converter 2 is protected from the overload state.

  As described above, in the first embodiment, in a multi-axis motor drive system in which one converter is commonly used for a plurality of servo amplifiers, the torque value of each axis (servo motor) and the speed detection value of the servo motor. And the voltage detection value are used to obtain the current consumption, the output current of the common converter is obtained from the total current consumption, which is the sum of the current consumption of each axis, and the overload judgment value obtained by time-determining this and the common converter's By comparing with a determination threshold according to the capacity, it is determined whether or not this common converter is in an overload state, and when the common converter is in an overload state, even if it becomes instantaneous, The operation of the multi-axis motor drive system is stopped, and even if the user accidentally uses this multi-axis motor drive system above the overload level, It is possible to not to fail over data.

  FIG. 6 is a flowchart showing a specific example of the processing operation of the second embodiment of the overload protection method and apparatus for the common converter of the multi-axis motor drive system and the multi-axis motor drive system according to the present invention. The second embodiment also has the configuration shown in FIG. 1, and a specific example thereof will be described below with reference to FIG.

  Further, steps S100 to S105 and steps S106 and S107 in FIG. 6 are the same as steps S100 to S105 and steps S106 and S107 in FIG. 5 in the first embodiment, and a description thereof will be omitted.

In FIG. 6, when the overload determination unit 23 compares the overload determination value I _s (k) with the determination threshold value I _th , when I _s (k) ≧ I _th (“No” in step S4). determines whether there is to be reduced a predetermined amount the output value P _i within the servo amplifier 3 a to 3 c (step S200), when the both can not be reduced (in step S "no"), of the first As in the first embodiment, the operation of each axis (servo amplifiers 3a to 3c) is stopped (step S106), and the control unit (not shown) is operated to stop the operation of each servo amplifier 3a to 3c (step S106). Then, an overload alarm is generated on the display unit 40 (step S107). As a result, the multi-axis motor drive system is stopped and the common converter 2 is protected from the overload state.

  Further, when there is an overload determination (“No” in Step S104) and any of the servo amplifiers 3a to 3c, for example, the output of the servo amplifier 3a can be reduced (“Yes” in Step S200), the above-described illustration. The control unit that does not perform this operation reduces the output of the target axis (here, the servo amplifier 3a) by a predetermined amount (step S201), and notifies the display unit 40 to that effect and outputs the target axis. An overload warning is displayed to display that the reduction has been made (step S202), the process proceeds to step S105, and the operation of the multi-axis motor drive system is continued as described above. Thereby, the common converter 2 is protected from an overload state while continuing the operation.

  As described above, in the second embodiment, in a multi-axis motor drive system in which one converter is commonly used for a plurality of servo amplifiers, the torque value of each axis (servo motor) and the detected speed value of the servo motor. And the voltage detection value are used to obtain the current consumption, the output current of the common converter is obtained from the total current consumption, which is the sum of the current consumption of each axis, and the overload judgment value obtained by time-determining this and the common converter's This is to determine whether this common converter is in an overload state by comparison with a determination threshold according to the capacity, and when the common converter is in an overload state, the output of one of the servo amplifiers is reduced. Therefore, the load of the common converter can be reduced and the overload state can be avoided. However, when the output of any servo amplifier cannot be reduced, if the servo amplifier that can reduce the output is continuously searched, the common converter will not be protected due to the overload state during that time. As in the embodiment, the operation of all servo amplifiers is stopped. Thereby, a common converter can be protected from an overload state. Note that it is possible to select whether all servo amplifiers are stopped or the output of any one of them is lowered when the common converter is overloaded.

1 is a block configuration diagram showing a first embodiment of an overload protection method and apparatus for a multi-axis motor drive system and its common converter according to the present invention. It is a figure which shows schematic structure of the overload protection apparatus of the common converter by this invention in a multi-axis motor drive system. It is a figure which shows the change of the output value and consumption current in the power running area and regeneration area in the servo amplifier shown in FIG. It is a graph which shows roughly the relationship between the total consumption current value _Icvo and the complementary value f ( _Icvo ) of the process in the time calculation part in FIG. It is a flowchart which shows the processing operation of 1st Embodiment shown in FIG. It is a flowchart which shows the processing operation of 2nd Embodiment of the overload protection method and apparatus of the multi-axis motor drive system and its common converter by this invention. It is a system configuration figure showing an example of a multi-axis motor drive system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power source 2 Common converter 3a, 3b, 3c Servo amplifier 4a, 4b, 4c Servo motor 5a, 5b, 5c Position sensor 10a, 10b, 10c Current consumption calculation part 20 Overload detection part 21 Converter output current calculation part 22 Time limit calculation Unit 23 Overload determination unit 30 Inverter 31 Current detection unit 32 Current control calculation unit 33 Position control calculation unit 34 Speed calculation unit 35 Speed control calculation unit 36 Voltage detection unit 40 Display unit

Claims (11)

In a method for overload protection of a common converter of a multi-axis motor drive system in which alternating current is converted into direct current by one common converter and supplied to a plurality of servo amplifiers, and a servo motor is driven for each of the plurality of servo amplifiers.
The current consumption for each of the plurality of servo amplifiers is obtained, and a complementary value for complementing the overload determination value corresponding to the total current consumption obtained by adding the plurality of current consumptions is used in the previous overload determination. The result of determining whether or not the common converter is in an overload state by comparing the overload determination value obtained in addition to the overload determination value with a preset threshold value corresponding to the capacity of the common converter When the common converter is determined to be in an overload state, the operation of all of the plurality of servo amplifiers is stopped. In a method for overload protection of a common converter of a multi-axis motor drive system in which alternating current is converted into direct current by one common converter and supplied to a plurality of servo amplifiers, and a servo motor is driven for each of the plurality of servo amplifiers.
The current consumption for each of the plurality of servo amplifiers is obtained, and a complementary value for complementing the overload determination value corresponding to the total current consumption obtained by adding the plurality of current consumptions is used in the previous overload determination. The result of determining whether or not the common converter is in an overload state by comparing the overload determination value obtained in addition to the overload determination value with a preset threshold value corresponding to the capacity of the common converter When it is determined that the common converter is in an overload state, if there is a servo amplifier capable of reducing the output by a predetermined amount among the plurality of servo amplifiers, the output of the servo amplifier is reduced by the predetermined amount. An overload protection method for a common converter, characterized in that the operation of all the plurality of servo amplifiers is stopped. In the overload protection method of the common converter according to claim 1 or 2,
The overload of the common converter, wherein the current consumption is obtained from a torque value of the servo motor, a speed detection of the servo motor, and a direct current DC voltage detection value supplied from the common converter to the plurality of servo amplifiers. Protection method. In the overload protection method of the common converter of any one of Claims 1-3,
An overload protection method for a common converter, characterized in that, when the total consumption current is negative, the overload determination value is obtained by setting the total consumption current to zero. The overload protection method for a common converter according to claim 4,
The overload determination value is a value obtained by converting the total consumption current into the complementary value corresponding to the rising temperature or falling temperature of the common converter, and adding or subtracting the complementary value to the previously determined determination value. A common converter overload protection method. In an overload protection device for a common converter of a multi-axis motor drive system that converts alternating current to direct current with a single common converter and supplies it to a plurality of servo amplifiers, and drives a servo motor for each of the plurality of servo amplifiers.
First calculation means for obtaining current consumption for each of the plurality of servo amplifiers, and second calculation means for obtaining total consumption current by adding the consumption currents of the plurality of servo amplifiers obtained by the first calculation means. When the complementary value to complement the overload judgment value corresponding to the total current consumption for the overload determination value determined by adding the previous overload judgment value used in the previous overload determination, is preset A third calculation means for comparing the common converter with a threshold value according to the capacity of the common converter and determining whether the common converter is in an overload state; and the common converter is overloaded by the third calculation means. An overload protection device for a common converter, comprising: operation control means for stopping the operation of all of the plurality of servo amplifiers when it is determined that In an overload protection device for a common converter of a multi-axis motor drive system that converts alternating current to direct current with a single common converter and supplies it to a plurality of servo amplifiers, and drives a servo motor for each of the plurality of servo amplifiers.
First calculation means for obtaining current consumption for each of the plurality of servo amplifiers, and second calculation means for obtaining total consumption current by adding the consumption currents of the plurality of servo amplifiers obtained by the first calculation means. When the complementary value to complement the overload judgment value corresponding to the total current consumption for the overload determination value determined by adding the previous overload judgment value used in the previous overload determination, is preset A third calculation means for comparing the common converter with a threshold value according to the capacity of the common converter and determining whether the common converter is in an overload state; and the common converter is overloaded by the third calculation means. If there is a servo amplifier that can reduce the output by a predetermined amount among the plurality of servo amplifiers, the output of the servo amplifier is reduced by the predetermined amount. Common converter overload protection device being characterized in that and an operation control means for stopping the work. The overload protection device for a common converter according to claim 6 or 7,
The first calculation means obtains the consumption current from a torque value of the servo motor, speed detection of the servo motor, and a DC voltage detection value of a DC supplied from the common converter to the plurality of servo amplifiers. A common converter overload protection device. The overload protection device for a common converter according to any one of claims 6 to 8,
The third calculation means obtains the overload determination value by setting the total consumption current to zero when the total consumption current obtained by the second calculation means is negative. Overload protection device. The overload protection device for a common converter according to claim 9,
The third calculation means converts the total consumption current into the complementary value corresponding to the rising temperature or falling temperature of the common converter, and adds or subtracts the complementary value to the previously obtained determination value to perform the overload. An overload protection device for a common converter, characterized in that a determination value is obtained.   11. A common converter according to claim 6, a plurality of servo amplifiers that respectively drive a plurality of servo motors, a common converter that converts alternating current into direct current and supplies the same to the plurality of servo amplifiers simultaneously. And a multi-axis motor drive system.

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