JP2001178176A - Control apparatus for servo motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly obtain a control apparatus which controls a servo motor with precise detection. SOLUTION: The control apparatus for the servomotor is provided with an electrically driven motor 1. The control apparatus is provided with detection means 4, 32, 33 which detect its driving or operating. The control apparatus is provided with control means 12 to 14 which generate drive commands Vns on the basis of their detection results Ff, If, Vf and control commands Fc, Vc. The control apparatus is provided with a pulse-width modulation means 150, which performs pulse-width modulation on the basis of the drive commands Vns and which generates a plurality of pulse signals Up, Vp, Wp. The control apparatus is provided with a power conversion circuit 30, which generates the drive current of the electrically driven motor 1, on the basis of the pulse signals. By the pulse-width modulation means 150, the pulse signals are made a free so that the the drive current does not flow at least once at each cycle, and the detection results are sampled in the free state. Thereby, the detection results are always sampled surely in a state that a switching noise does not exist.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo motor control device which detects current, rotational speed, operating force, and the like, and performs control based on a detection value obtained by sampling the detection result. The present invention relates to a technique for obtaining accurate detection values and appropriately performing control.

[0002]

2. Description of the Related Art A servo motor control device whose block diagram is shown in FIG. 7 includes a speed control (speed following) for following a motor rotational speed to a speed command, and a force control for following an operating force of an operating part to a force command. (Force following) is appropriately switched. Some electric motor driving units in presses, injection molding machines, die cast machines, and the like use an electric motor 1
It is sometimes convenient to automatically switch the control of the electric motor 1 from the speed control to the force control in response to the sudden increase in the force when the operating unit 2 is driven at the operation limit 3 when the operating unit 2 is driven, For this purpose, in this device, a force detection unit 4 (detection means) for detecting a final acting force generated in the operation unit 2 driven by the electric motor 1 is attached to the operation unit 2 and the output is obtained. Based on the force Ff, only one of the speed following and the force following is made effective.

[0003] More specifically, a software servo system using a microprocessor 10 as a control circuit is provided. An input circuit 20 is added to the microprocessor 10, and between the microprocessor 10 and the electric motor 1. A power conversion circuit 30 is provided. The power conversion circuit 30 mainly includes a drive circuit 31 having a power transistor and generating a drive current to the electric motor 1 by a switching operation of the power transistor. The microprocessor 10 converts a set of three pulse signals Up, Vp, and Wp from the microprocessor 10. The switching operation is performed based on the received signal. A current detection unit 32 (detection means) that detects a drive current If as a drive state of the electric motor 1 is provided between the electric motor 1 and the electric motor 1.
Further, a speed detection unit 33 (detection means) for detecting the rotation speed Vf as a direct operation state of the electric motor 1 is also provided on the electric motor 1 or its output shaft. Note that the above-described force Ff is detected by interposing the operation unit 2 between the electric motor 1 and the force detection unit 4, and thus indicates an indirect operation state of the electric motor 1.

[0004] These detection results (If, Vf, Ff)
Is input to the microprocessor 10 via the input circuit 20 and the like, and is used for determination in order control, feedback control for following, and the like. Therefore, the input circuit 20 converts the force Ff into the A / D conversion circuit 21 ( Latch 2 after digitizing while sampling at any time with sampling means)
The data is transmitted to the microprocessor 10 via the second or the like. Although illustration is omitted, the same applies to other input circuits.

The microprocessor 10 has a sequence control routine 11 as control means for generating a drive command Vn based on the sampling values (If, Vf, Ff).
And a speed control routine 12, a force control routine 13, and a current control routine 14, which are further installed.
Based on the drive command Vn, pulse width modulation is performed as will be described later to generate a plurality of pulse signals Up, Vp, and Wp and send them to the drive circuit 31.
Routine 15 is also installed.

[0006] The sequence control routine 11 follows a series of sequences including, for example, a constant speed advance process and a pressure holding process.
An appropriate speed command Vc and force command Fc are generated, the speed command Vc is given to the speed control routine 12, the force command Fc is given to the force control routine 13, and the speed control and the force control are performed according to the magnitude of the force Ff. A selection command for designating either one is issued. Moreover, the current control routine 1
4 receives the current command from the speed control routine 12 when the speed control is selected and receives the current command from the force control routine 13 when the force control is selected according to the selection command. The drive command Vn is generated such that the current If follows the command. Thereby, the generation of the drive command Vn is selectively performed based on the sampling value Ff and the force command Fc according to the sampling value of the force Ff, or the other sampling value V
This is performed based on f and the speed command Vc.

The speed control routine 12 generates a current command to make the speed Vf of the electric motor 1 close to and match the received speed command Vc. In combination with the generation of the drive command Vn for matching the drive currents, the current control is performed as a minor loop, and the speed control is performed as a feedback loop outside the multiplex feedback control. Speed control is performed so that the rotation speed of the electric motor follows the command. The force control routine 13 performs a force control that causes the operating force of the operating unit to follow the received force command by generating a current command that causes the force Ff to approach and match the received force command Fc. Since the current command to be generated corresponds to the torque which is a kind of force, the calculation content and the like are different from those of the speed control routine 12, so that the speed control routine 12 is provided separately therefrom.

As a control method based on the speed control routine 12 and the current control routine 14, a method using well-known PID control or a method using dq conversion is disclosed (Japanese Patent Laid-Open No. 10-2).
The driving command Vn, which is passed from time to time from the current control routine 14 to the PWM routine 15, finally determines any phase, for example, the V phase of the electric motor 1. The sine component is given by the reference vector, and the sine component is the drive current V (V
n), the sine component of the vector advanced by 120 ° corresponds to the drive current U (Vn) for the U phase, and the sine component of the vector delayed by 120 ° corresponds to the drive current W (Vn) for the W phase. Is to be applicable.

Here, the drive circuit 31 will be described in detail (see FIG. 8 (a)). In order to drive the three-phase electric motor 1, one of the drive circuits 31 conducts in accordance with the pulse signal Up, while the other drives. , A pair of transistors Q1 and Q2 connected in series, a pair of transistors Q3 and Q4 that alternately turn on and off according to a pulse signal Vp, and a pair of transistors Q that alternately turn on and off according to a pulse signal Wp.
5, Q6. Each transistor is a power transistor such as an IGBT, and a flywheel diode, a snubber circuit (not shown), and the like are appropriately added as necessary. Further, the three transistor pairs are provided with a rectifier circuit 31b for converting a commercial alternating current into a direct current.
When the positive-side transistors Q1, Q3, and Q5 are turned on and in a conducting state, current flows into each phase U, V, and W of the electric motor 1 while the positive-side transistors Q1, Q3, and Q5 are turned on.
When the negative-side transistors Q2, Q4, and Q6 are on and in a conducting state, current is drawn from each phase U, V, and W of the electric motor 1. Note that pulse signals Up and V are applied between these transistors and the microprocessor 10.
An amplifier for amplifying and generating a base current corresponding to p and Wp, a circuit for preventing a pair of transistors from turning on at the same time and causing a fault such as a short circuit, and the like are also provided.

The PWM routine 15 receives a drive command Vn from the current control routine 14 as pulse width modulation means for linking the drive circuit 31 with the above-described current control routine 14, and based on the received drive command Vn, generates a plurality of pulse signals Up and Vp. , Wp and send them to the drive circuit 31 via an output port (not shown). The pulse width modulation process performed at that time is shown in FIG.
(B)), it is common to use an appropriate constant frequency triangular wave signal Z or the like. When the value of the U-phase drive current U (Vn) corresponding to the drive command Vn exceeds the triangular wave signal Z, When the pulse signal Up is set to the high state, that is, the transistor Q1
Is turned on, and when the drive current value U (Vn) is lower than the triangular wave signal Z, the pulse signal Up is set to the low state, that is, the transistor Q2 is turned on, thereby generating the pulse signal Up. Similarly, the V-phase drive current value V
A pulse signal Vp is generated based on the magnitude of (Vn) and the triangular wave signal Z, and a pulse signal Wp is generated based on the magnitude of the W-phase drive current value W (Vn) and the triangular wave signal Z.

The control device for such a servo motor uses an appropriate speed command Vc and force command F in the sequence control routine 11.
c is generated, and the following control is performed with the command as a control target in the speed control routine 12 or the like. For example, when constant pressure control or constant torque control is performed after constant speed feed, the speed command V
c is given as a constant value corresponding to the constant speed feed, and the force command Fc is given as a constant value corresponding to constant pressure control or the like. Then, assuming that α is a predetermined constant, while the force Ff is smaller than the constant value α, the speed control is selected by the sequence control routine 11, and control is performed to cause the speed Vf to follow the speed command Vc. Thereafter, the operation unit 2 reaches the operation limit 3 and its operation is restricted, and as a reaction, the force Ff suddenly increases, and when the force Ff exceeds a certain value α, the force control is performed by the sequence control routine 11. Is selected, and control for causing the force Ff to follow the force command Fc is performed.

At this time, each time any of the drive current values U (Vn), V (Vn), W (Vn) corresponding to the drive command Vn and the triangular wave signal Z are switched, the pulse signal Up,
Either Vp or Wp changes, and the currents of the U-phase, V-phase, and W-phase of the electric motor 1 frequently repeat reversal or the like in response to the change. The drive current to the motor 1 substantially matches the drive command Vn. Also,
The sampling of the force Ff by the A / D conversion circuit 21 is performed at any time in the shortest operable cycle (see the arrow S in FIG. 8B). The sampling of the speed Vf and the current If is performed in substantially the same manner, and the pulse signal U
This is performed at a timing irrelevant to the generation of p, Vp, and Wp.

[0013]

In such a conventional servo motor control device, since the generation of the pulse signal and the sampling of the detection result are performed independently, the start of the pulse in the pulse signals Up, Vp and Wp is started. The end timing and the sampling timing of the detection result (If, Vf, Ff) may overlap. Moreover, such occurrences are random and often infrequent.

However, at the pulse edge, that is, at the start and end timings of the pulse, the transistor is turned on and off in the drive circuit 31 in response to the reversal, and the coil current of the electric motor 1 is switched accordingly. However, considerably large switching noise is generated. Furthermore, instantaneous fluctuations and pulsations also appear in the motor output. If the sampling of the detection result happens to be performed at that timing, a large error will enter the detected value to be fed back. To deal with this, a circuit to prevent noise propagation is added, and a smoothing means is incorporated in the detecting means to reduce and disperse noise and fluctuations. Therefore, the effects of switching noise and output fluctuation are not completely suppressed.
For this reason, the control state fluctuates due to the influence of the error and the like, and further fluctuates to the operating state. Moreover,
Since the occurrence of such fluctuations is rare and unpredictable, there is a limit to the adjustment at the start-up adjustment, etc., and it must be patient that the operation state and the product due to the operation have some variation. did not become.

In particular, when the force generated in the operating portion is detected and fed back to the control, or when the control state is determined based on the detected force, the switching noise and the motor output fluctuation overlap, and the influence is affected. They may be offset or added. For this reason, the fluctuation accompanying the sampling value of the detection result has a larger width and rarely appears, and thus is difficult to cope with. If the switching is delayed or too early due to the determination based on the detection result, the control order may be reversed in some cases, which may lead to undesired undesired operations and results. , Its impact is great.

Therefore, it is a technical problem how to determine how the influence of the switching of the drive current affects the sampling value of the detection result. At that time, it is also important to make it as simple as possible without impairing the driving ability and responsiveness. The present invention has been made to solve such a problem, and an object of the present invention is to realize a servomotor control device that obtains an accurate sampling value of a detection result and performs appropriate control.

[0017]

Means for Solving the Problems First to third means for solving the problems described above are described below.
The configuration and operation and effect will be described below.

[First Solution] A control device for a servomotor according to a first solution (as described in claim 1 at the time of filing the application) includes an electric motor and a driving state (such as a driving current) of the electric motor. (With or instead of speed, force, etc.)
Detecting means for detecting an operation state; control means for generating a drive command based on the detection result and a control command (received or generated); and pulse width modulation based on the drive command (for three-phase or the like). ) A servo motor control device comprising: a pulse width modulation means for generating a plurality of pulse signals; and a power conversion circuit for generating a drive current for the electric motor based on the pulse signals. The pulse state of each of the pulse signals is set to a free state in which the driving current does not flow at least once in each of a basic cycle, which is a unit time for repeating the processing, that is, a cycle. That means that the sampling is automatically performed by the pulse signal (the pulse state is synchronized with each cycle or some cycles). It performed when the state (has become) (those in which), is that.

In the servo motor control device according to the first solution, the timing at which the drive current is not switched is periodically secured, and the sampling of the detection result is performed only at that time. Will be Therefore, since sampling is always performed reliably without switching noise, even if the variance of noise etc. is not strengthened, it is better not to scatter, but rather a value with less error is sampled. Becomes

Thus, when sampling the detection result, an accurate sampling value can be stably obtained without adding or strengthening a smoothing circuit or the like, and while avoiding inconveniences such as a decrease in responsiveness. Can be obtained. Therefore, according to the present invention, it is possible to realize a servomotor control device that obtains an accurate detection value and performs appropriate control.

[Second solving means] The servo motor control device according to the second solving means is the same as the servo motor controlling device according to the first solving means, wherein the force generated in the operating portion is a pulse signal free. This is explicitly included in one of the detection targets sampled in synchronization with the state.
That is, (as described in claim 2 at the beginning of the application), an electric motor, a force detecting unit for detecting a force generated in an operating unit driven by the electric motor, and a detection result (received or generated) Control means for generating a drive command based on the control command; pulse width modulation means for performing pulse width modulation based on the drive command to generate a plurality of (three-phase or the like) pulse signals; A power conversion circuit for generating a drive current for the electric motor, wherein the pulse width modulation means is provided at least once in each cycle (ie, a basic cycle that is a unit time for repeating processing). The pulse state of each of the pulse signals is set to a free state in which the drive current does not flow, and a means for sampling the detection result is provided. Ring (the pulse state in synchronization with each cycle or part cycle) (those) that carried out when a free state (has become) of the pulse signals, is that.

In the servo motor control device according to the second solution, the operating force and the like affected by the motor output fluctuation due to switching, in addition to the switching noise, can be surely maintained without any switching noise. Sampled. As a result, the operating conditions and control characteristics vary greatly depending on the application purpose and application target, and even the raw materials, etc. Can be adopted. Therefore, according to the present invention,
It is possible to realize a servomotor control device that obtains an accurate detection value of the operation unit and performs appropriate control based on the operation state.

[Third Solution] The servomotor control device according to the third solution is the same as the servomotor control device according to the second solution, wherein the force generated in the operating portion is subject to synchronous sampling. In addition to being included, speed control and force control are selectively performed, and the selection is switched based on a force sampling value. That is, (as described in claim 3 at the beginning of the application), the electric motor, a speed detecting unit for detecting the rotational speed thereof, and a drive command based on the detection result and the (received or generated) speed command. Control means for generating, pulse width modulation means for performing pulse width modulation based on the driving command to generate a plurality of (three-phase, etc.) pulse signals, and driving current for the electric motor based on the pulse signals In a servo motor control device including a power conversion circuit, a force detection unit that detects a force generated in an operation unit driven by the electric motor, and a sampling unit that samples a detection result of the force detection unit. Wherein the control means selectively generates the drive command according to the sampling value (instead of performing the drive command based on the rotation speed and the speed command). And (forced or generated) force command, wherein the pulse width modulation means performs at least once every cycle (a basic cycle, which is a unit time for repeating the process). The pulse state is set to a free state in which the drive current does not flow, and the sampling means changes the sampling to the free state (the pulse state is synchronized with each cycle or some cycles) of the pulse signal. (When it is).

In the servo motor control device according to the third solution, the operating force and the like which are susceptible to switching are always sampled without switching noise, and in addition to the accurate sampling, Selection switching between speed control and force control is performed based on the appropriate sampling value / detection value. As a result, the determination of the switching timing performed based on the operation state is always performed stably and appropriately, which contributes to further stabilization of the operation state. Therefore, according to the present invention, it is possible to realize a servomotor control device capable of stably performing appropriate control based on an operation state by obtaining an accurate detection value of an operation section.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the servo motor control apparatus of the present invention achieved by the above-described solution will be described with reference to the following first to fourth embodiments. The first embodiment shown in FIGS. 1 and 2 embodies the third solution means described above, and the second embodiment shown in FIG.
The embodiment, the third embodiment in FIG. 4, and the fourth embodiment in FIG. 5 are modifications thereof. Although illustration is omitted, the fifth embodiment is an extended example of them, and corresponds to the above-described second solving means. Further, the sixth embodiment, which is also omitted from the drawing, is a further extended example, and corresponds to the above-described first solving means. In the drawings and the like, the same reference numerals are given to the same components as those in the related art, so that the overlapping description will be omitted, and the following description will focus on the differences from the related art.

[0026]

[First Embodiment] A first embodiment of a servo motor control device according to the present invention.
A specific configuration of the embodiment will be described with reference to the drawings. FIG. 1 is a block diagram showing the circuit configuration and the like. FIG. 2 shows the control method, and FIG.
FIG. 3 is an explanatory diagram of vector control used for current control and the like, and FIG. 4B is a time chart for explaining a PWM method and the like.

The servo motor control device differs from that of the prior art described above in that the PWM routine 15 is replaced by a PWM routine 150 (pulse width modulation means) for generating a sampling trigger S, and the force Ff Is that the A / D conversion circuit 21 (sampling means) for receiving the sampling trigger S has become the A / D conversion circuit 210 for receiving the sampling trigger S.

The A / D conversion circuit 210 may be a sequential conversion type or a batch conversion type as long as the operation speed and the required accuracy are satisfied. However, prior to digitization, the A / D conversion circuit 210 samples the force Ff and holds it for a required time. In this case, a trigger signal for determining the sampling timing can be taken in from the outside. The wiring is connected so as to receive the sampling trigger S from the microprocessor 10 via an appropriate output port (not shown) as the trigger signal.

The PWM routine 150 is based on the fact that the drive command Vn passed from the current control routine 14 is expressed as follows using specific zero vectors V0, V7 and base vectors V1 to V6 as base vectors as follows. A width modulation process is performed. That is, these vectors are (see FIG. 2A). For example, when the zero vector V0 is made to correspond to the state where all the pulse signals Up, Vp and Wp are low, the transistors Q2 and Q
4 and Q6 are turned on, the drive current flowing through the electric motor 1 becomes zero, and the electric motor 1 is in a free state. Pulse signal U
When a state in which p, Vp, and Wp are all high is represented by a zero vector V7, in that state, the transistors Q1,
Q3 and Q5 are turned on, and the electric motor 1 is also in a free state.

The base vector V1 corresponds to the state where the pulse signal Up is high and the other pulse signals Vp and Wp are low, and the pulse signal Wp is high when the pulse signals Up and Vp are high.
When the base vector V2 corresponds to the low state, and the state in which any one of the pulse signals is inverted corresponds to the remaining base vectors V3 to V6. The six base vectors V1 to V6 are completed. When the vector of the drive command Vn is located between two adjacent base vectors, for example, between the two base vectors V1 and V2, the vector Vn is a pair of vectors Va projected to the two base vectors V1 and V2. , Vb.

Therefore, the PWM routine 150 (FIG. 2)
(See (b)), a pair of clocks corresponding to the clock vector Vn at any time, for example, every predetermined period T of about several tens of ms, which is periodically started by a timer interrupt processing routine or the like and also performs processing such as time measurement. An operation for obtaining the vectors Va and Vb is performed, and a time tb corresponding to the vector Va is obtained by an operation corresponding to the equation [tb = (Va / V1) × (T / 2)], and a time tc corresponding to the vector Vb is obtained. By the formula [t
c = (Vb / V2) .times. (T / 2)]. Furthermore, the remaining time obtained by subtracting those times from the first half and the second half of the period T (T−2 × (tb + tc))
Is proportionally divided into a time ta corresponding to the zero vector V0 and a time td corresponding to the zero vector V7.

Then, in the corresponding cycle T, as the times ta, tb, tc, td, tc, tb, and ta elapse, the pulse signals Up, Vp, and Wp become high.
In the low state, the zero vector V0 and the base vector V1
, Base vector V2, zero vector V7, base vector V2, base vector V1, and zero vector V0. Further, the sampling trigger S is transmitted at the first or last time point of the corresponding cycle T and at the time point when a half cycle (T / 2) has elapsed. As a result, one of the zero vectors V0 and V7 comes at both ends and the center of the period T, and the sampling trigger S is reliably issued within the time corresponding to the zero vector. And
Such a PWM routine 150 is a pulse width modulation means. In particular, the pulse state of each of the pulse signals Up, Vp, Wp is reduced to zero vectors V0, V7 at least once every period T, that is, every basic processing cycle. , That is, a free state in which the drive current does not flow.

Here, the other components will be described in detail. As the electric motor 1, a permanent magnet synchronous motor or the like is used for a brushless DC servo motor, and a squirrel-cage induction motor is frequently used for an induction motor. A combination of a rotation / linear motion conversion mechanism such as a ball screw and a pressurizing mechanism such as a ram cylinder, a swing mechanism connected via a reduction gear or the like, and the like are used as the operating unit 2. The pressure detector 4 employs a pressure gauge (pressure gauge) or the like when detecting pressure as the force Ff, and employs a torque gauge or the like when detecting torque as the force Ff. The operation limit 3 is a cylinder end or filling of a mold with a filler.

The control routines 11 to 14 and the PW
The microprocessor 10 that executes the M routine 150 by program processing includes a one-chip microcomputer with a built-in program memory and data memory, a processor system in which a CPU IC and a peripheral IC such as a memory are appropriately combined, and the like. It is adopted as appropriate depending on the situation. For the current detection unit 32, a Hall element or the like having excellent responsiveness and high accuracy is frequently used, and for the speed detection unit 33, various speed sensors such as an encoder based on intermittent light are used.

The usage and operation of the servo motor control device of the first embodiment will be described.

Also in this case, if the constant pressure control is performed after the constant speed feed, an appropriate speed command Vc and force command Fc are given by the sequence control routine 11, and the speed Vf is first set by the speed control routine 12 and the like. Speed control for following Vc is performed, and then, when the selection switching is determined by the sequence control routine 11 in response to the rapid increase of the force Ff, force control for following the force Ff to the force command Fc is performed. As described above, the same operation as in the related art is performed as a whole.

However, when the operation at that time is viewed in detail (see FIG. 2), the drive command Vn is delivered from the current control routine 14 to the PWM routine 150 every cycle T,
The pulse signals Up, Vp, W are output by the WM routine 150.
p is generated and a sampling trigger S is sent. Then, the drive current supplied from the drive circuit 31 to the electric motor 1 is intermittent according to the pulse signals Up, Vp, Wp. If the drive current is averaged over the cycle T at that time, the amount of drive is In proportion to the magnitude of the command Vn, the direction of the current based on each phase U, V, W of the electric motor 1 matches the direction of the drive command Vn. Thus, also in this case, pulse width modulation corresponding to the drive command Vn is performed correctly, and the drive current of the electric motor 1 substantially matches the drive command Vn, so that appropriate drive is performed.

In this case, the sampling trigger S is sent from the microprocessor 10 to the A / D conversion circuit 210. The PWM routine 150 sends the sampling trigger S twice in each cycle T. Moreover,
This is because the pulse signals Up, Vp, Wp are zero vector V
0, V7 and the transistor Q1 of the drive circuit 31
It is issued only when ON / OFF of .about.Q6 is not performed at all (see FIG. 2B).

Then, such a sampling trigger S
The A / D conversion circuit 210 receives the transistor Q
At the timing when the switching of 1 to Q6 is not performed, there is no switching noise, and there is no fluctuation of the motor output, the force F
The sampling of f is performed. Thus, the sampling of the force Ff, which is the detection result of the force detection unit 4, is performed by the pulse signal U.
This is performed when p, Vp, and Wp are free. As a result, an accurate force Ff is always obtained.
Determination and selection switching, and the force control routine 13
Is also stably and accurately performed.

[0040]

Second Embodiment A servomotor control device according to a second embodiment, whose control method is illustrated by a time chart in FIG. 3, is different from that of the first embodiment in that the transmission of the sampling trigger S is performed every four cycles. That is, it is performed only once every four times the period T. in this way,
The transmission timing of the sampling trigger S is an integral multiple of a half cycle (T / 2) corresponding to the allocation of the zero vectors V0 and V7,
As long as it is equal to or longer than the shortest time in which repetition of 0 can be performed, it can be set as appropriate.

[0041]

Third Embodiment A servo motor control device according to a third embodiment, whose main part is shown in a block diagram in FIG. 4, is different from that of the first embodiment in that the PWM routine 150 generates the sampling trigger S.・ PW changed to not send
M routine 151 and PWM routine 151
This is the point that the timer interrupt processing routine 152 that repeatedly starts the operation at the cycle T generates the sampling trigger S at the same time as the start and sends it to the A / D conversion circuit 210. Also in this case, when the PWM routine 151 is started, the pulse signals Up, Vp, Wp are set to zero vectors V0, V0.
As long as the free state corresponding to 7 is obtained, an accurate sampling value of the force Ff without switching noise or the like can be obtained.

[0042]

Fourth Embodiment FIG. 5 shows an overall block diagram of the circuit configuration and the like. The servo motor control device of the fourth embodiment differs from that of the first embodiment in that the A / D conversion circuit 210 is different from that of the first embodiment. This is a point that the input circuit 20 has been moved to the force detecting section 4. Accordingly, an appropriate line driver or line receiver is introduced into the input circuit 20 so that the sampling trigger S reaches the A / D conversion circuit 210. In this case, the transmission data is digitized even with a cable having a force Ff which is generally long and easily picks up noise simply by adding a small circuit, and is transmitted to the microprocessor 10 because the data is hardly affected by noise. The value of the force Ff becomes more accurate.

[0043]

Fifth Embodiment In each of the above embodiments, the determination of switching from the constant speed control to the constant pressure control is made by the sequence control routine 11 based on the force Ff, that is, based on the detection result of the force detector 4. This is not essential for the application of the present invention, but may be any as long as it performs feedback control or the like based on the force Ff as in the force control routine 13. Nevertheless, it is possible to receive the effect of not being affected by not only switching noise but also fluctuations in motor output due to switching.

[0044]

Sixth Embodiment In each of the above embodiments, the detection result sampled in accordance with the sampling trigger S is only the force Ff, but other detection results, that is, the speed Vf, the current If, and the like are also obtained together with or without the force Ff. Alternatively, sampling may be performed in response to a sampling trigger S.
Even so, the effect of not being affected by switching noise can be enjoyed.

[0045]

[Others] In the above embodiment, the force control routine 13
Is passed to the current control routine 14, but the present invention is not limited to this.
May be passed to the speed control routine 12. In that case (see FIG. 6), the force control routine 13 calculates the difference between the force command Fc and the force Ff and passes the difference to the speed control routine 12, and the order control routine 11
A selection command may be generated according to the difference between the difference and the speed command Vc. Then, in the conventional example, α
Is unnecessary, and the operation state and the like are further stabilized.

The processing of each of the routines 11 to 14 and 150 by the microprocessor 10 is not limited to the program processing, but may be embodied by appropriate hardware logic or the like. May be embodied by the above-mentioned individual hardware, and may further include a plurality of microprocessors.

Further, the constant speed control and the constant pressure control are examples of the control method, and the present invention is not limited to this.
The present invention is also applicable and effective for control for changing the control target.

[0048]

As is apparent from the above description, in the servo motor control device according to the first solution of the present invention, sampling is always performed without switching noise. As a result, it is possible to stably obtain accurate sampling values while avoiding inconveniences such as a decrease in responsiveness. As a result, it is possible to realize a servo motor control device that obtains accurate detection values and performs appropriate control. There is an advantageous effect that it is possible.

Further, in the servo motor control device according to the second solution of the present invention, the force generated in the operating portion is sampled in synchronization with the free state of the pulse signal, thereby enabling the operation. There is an advantageous effect that appropriate control based on the operation state can be performed by obtaining an accurate detection value of the section.

Further, in the servo motor control device according to the third solution of the present invention, the selection switching between the speed control and the force control is performed based on accurate sampling values and detected values. As a result, it is possible to accurately determine and further stabilize the operating state, and as a result, to obtain an accurate detection value of the operating unit, to achieve a stable control of the servomotor based on the operating state of the servo motor control device There is an advantageous effect that it can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration and the like of a first embodiment of a servomotor control device according to the present invention.

FIG. 2 shows the control method, and FIG. 2 (a) is an explanatory diagram of vector control used for current control and the like;
(B) is a time chart for explaining the PWM method and the like.

FIG. 3 is a time chart showing a control method of a servo motor control device according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a main part of a third embodiment of the servo motor control device according to the present invention.

FIG. 5 is a block diagram showing a circuit configuration and the like of a fourth embodiment of the servo motor control device of the present invention.

FIG. 6 shows a servo motor control device according to the present invention.
It is a block diagram showing other modifications.

FIG. 7 is a block diagram of a conventional servo motor control device.

FIGS. 8A and 8B show details thereof, FIG. 8A is a circuit diagram of a drive circuit of a three-phase motor, and FIG. 8B is a time chart for explaining a PWM method and the like.

[Explanation of symbols]

1. Electric motor (electric motor, permanent magnet synchronous motor, cage induction motor) 2. Actuator (actuator, ball screw, advance / retreat mechanism,
Gears, swing mechanism) 3 Operation limit (stopper, abutting object, pressurized object, reaction force generator) 4 Force detection unit (action force detection, reaction force detection, pressure gauge, torque gauge, load cell) 10 Microprocessor (Control circuit) 11 Sequence control routine (selection switching means between speed control and force control) 12 Speed control routine (motor speed feedback control means, control means) 13 Force control routine (operating force feedback control means, control means) 14 Current Control routine (current feedback control means, control means) 15 PWM routine (pulse width modulation means) 20 Input circuit (peripheral circuit, control circuit) 21 A / D conversion circuit (operating force detection value sampling means) 22 Latch (register, input) Port, input / output interface) 30 power conversion circuit 31 drive circuit (current output unit, PWM inverter, power output stage) 32 current detection unit (Hall CT, Hall element, insulation amplifier) 33 Speed detector (tach generator, resolver, encoder) 150 PWM routine (pulse width modulation means) 151 PWM routine (pulse width modulation means) 152 Timer interrupt processing routine 210 A / D Conversion circuit (operating force detection value sampling means) Fc force command (control command) Vc speed command (control command) Vn drive command (generated vector command) If current (detection target, drive state) Vf speed (rotation speed, detection target) , Operating state) Ff Force (operating force, detection target, operating state) S Sampling trigger Up, Vp, Wp Pulse signal V0, V7 Zero vector (base vector in free state) V1 to V6 Base vector (base vector in active state)

Continuation of the front page (72) Inventor Uhiko Takeuchi 2-16-46 Minami Kamata, Ota-ku, Tokyo Inside Tokimec Co., Ltd. (72) Inventor Masao Oba 2-16-46 Minami Kamata, Ota-ku, Tokyo Tokimec Co., Ltd. F term (reference) 5H560 BB04 BB12 DA02 DA07 DA10 DB07 DC01 DC12 EB01 GG04 JJ13 SS01 TT01 UA02 XA12 XB10 5H575 BB05 BB06 DD03 GG02 HA08 JJ03 JJ14 JJ18 LL07 LL10 LL22 LL29

Claims (3)

[Claims] An electric motor, detecting means for detecting a driving state or an operating state of the electric motor, control means for generating a driving command based on the detection result and a control command, and performing pulse width modulation based on the driving command. A pulse width modulation means for generating a plurality of pulse signals, and a power conversion circuit for generating a drive current for the electric motor based on the pulse signals. A servo, wherein the pulse state of each of the pulse signals is set to a free state in which the drive current does not flow at least once per cycle, and the detection result is sampled when the pulse signal is in a free state. Motor control device. 2. An electric motor, a force detection unit for detecting a force generated in an operation unit driven by the electric motor, a control unit for generating a drive command based on the detection result and a control command, and a drive unit for the drive unit. A servo motor control device comprising: pulse width modulation means for performing pulse width modulation based on a command to generate a plurality of pulse signals; and a power conversion circuit for generating a drive current for the electric motor based on the pulse signals. The pulse width modulation means sets the pulse state of each of the pulse signals to a free state in which the drive current does not flow at least once per cycle, and the sampling of the detection result is performed in a free state of the pulse signal. A servomotor control device, which is performed at a time. 3. An electric motor, a speed detecting unit for detecting a rotation speed of the electric motor, control means for generating a drive command based on the detection result and a speed command, and performing pulse width modulation based on the drive command. A servo motor control device comprising: a pulse width modulation means for generating a plurality of pulse signals; and a power conversion circuit for generating a drive current for the electric motor based on the pulse signals. A force detection unit that detects a force generated in the operation unit; and a sampling unit that samples a detection result of the force detection unit.The control unit selectively generates the drive command according to the sampling value. The pulse width modulation is performed based on the sampled value and the force command. Wherein is intended to free state does not flow a driving current, said sampling means, the control apparatus of a servo motor and performing the sampling at a free state of the pulse signal.