JPH0370487A - Servo motor drive monitor - Google Patents

Abstract

PURPOSE:To facilitate incorporation of a servo system and to minimize the influence of a malfunction by providing exciting current detecting means for phases of a servo motor, means for sequentially storing the detected result, and means for outputting a detected result by a request from an external device. CONSTITUTION:The drive of a servo motor 20 is controlled by a logic circuit having a high speed CPU 10a and a CPU 10b as a center, and a controller 10 has a feedback control type. Current detecting coils 22, 24 for measuring an exciting current for detecting a torque, and an encoder 26 for detecting a rotating position, a rotating speed are provided. A control program for forming a servo system of the first ROM 10d, the second ROM 10e of the controller 10. Thus, incorporation with the servo system can be facilitated, and influence of a malfunction can be minimized.

Description

[Detailed Description of the Invention] [Industrial Application Field] Invention 1 Regarding a servo motor drive monitoring device that monitors the drive status of a servo system that tracks and controls an electric motor, a servo motor drive monitoring device that has particularly excellent detection accuracy and detection speed is provided. The present invention relates to a motor drive monitoring device.

[Prior Art] Servo systems are often used in various NC machine tools such as robots and measuring devices. These servo systems (1) have a basic configuration in which the drive state of the servo motor is detected and the amount of power supplied to the servo motor is feedback-controlled so that the drive state follows the target state.

Here, we need to control the amount of electricity (actually, the power control circuit, such as PWM control of the inverter circuit)
This is achieved by appropriately adjusting the excitation current of the servo motor.

For boat fishing, there is a position control loop that calculates the speed target value from the deviation between the input target rotational position and the actual servo motor rotational position, and a position control loop that calculates the speed target value from the deviation between the input target rotational position and the actual rotational position of the servo motor. A speed control loop that calculates a current target value from the deviation from the rotational speed of the servo motor, and further controls the power control circuit to minimize the deviation between the current target value thus calculated and the actual excitation current of the servo motor. The desired servo system is constructed by forming the current control loop for execution and the above triple feedback loop.

In addition, in the servo system constructed as described above, if an abnormality such as a disconnection or short circuit occurs in the servo motor,
Abnormality avoidance processing is required to stop the supply of unnecessary power to the servo motor. For this reason, in addition to the triple feedback loop described above, the servo system is also equipped with a servo motor drive monitoring device.The monitoring results are output to the feedback system, making it possible to immediately take action to avoid abnormalities in the servo system. It is configured like this.

For example (e) As a servo motor drive monitoring device, a torque sensor that detects the output torque of the servo motor, a current sensor installed in the power supply section of the power control circuit, etc. are used, and when an abnormality is detected by these sensors, the power is Abnormality avoidance processing such as stopping the drive of the control circuit is being executed.

[Problems to be Solved by the Invention] Conventional servo motor drive monitoring devices use a torque sensor, which is a new detection device that is completely different from the devices that make up the triple feedback loop, which is the basic component of the servo system.
Requires current sensor etc.

Therefore, the overall configuration of the servo system becomes complicated and expensive. Furthermore, as the number of servo system components increases, the overall size of the device increases, making it difficult to ensure reliability. Therefore, conventional servo systems equipped with a servo motor drive monitoring device are limited in their applicable fields, and are not very versatile. Current sensors, etc. that detect the amount of electric power (t, servo motor l) It is possible to detect an abnormality when the influence of an abnormality such as a disconnection or short circuit that occurs spreads to the output torque or power control circuit. There is a considerable time delay in detection.In other words, even with conventional servo motor drive monitoring devices, it is not possible to deal with cases where immediate abnormality avoidance is required. Secondary damage caused by the overcurrent caused by the overcurrent, such as burnout of the servo motor excitation winding or destruction of the semiconductor switching elements that make up the power control circuit. It is known that the conventional servo motor drive monitoring device 1 can prevent such secondary damage.
Since there is a large delay in detecting the next abnormality, the abnormality avoidance processing of the servo system does not work effectively, and the present invention has a high possibility of causing damage to expensive servo system components]. The aim is to solve the above-mentioned unresolved problems with servo motor drive monitoring devices.
Servo motor drive monitoring that is easy to install alongside the servo system to be monitored, is compact overall, has high reliability, and is highly responsive and economical, making it possible to minimize the spread of abnormalities. The purpose is to provide equipment.

[Means for Solving the Problems] As shown in FIG. 1, a servo motor drive monitoring device 1 of the present invention includes a power control circuit C between a voltage source C1 and a servo motor Sv.
2 from the voltage source C1 to the servo motor S
The servo motor SV is controlled by controlling the amount of power supplied to the servo motor SV.
A servo motor drive monitoring device for monitoring a servo system that tracks the drive state of the servo motor to a target state, comprising: excitation current detection means C3 for detecting the excitation current of each phase of the servo motor Sv; and the excitation current detection means C3. The detection result storage means C4 sequentially stores the detection results of the detection result storage means C4, and the detection result output means C5 outputs the stored contents of the detection result storage means C4 in response to a request from an external device.

[Function] In the servo motor drive monitoring device of the present invention, the excitation current detection means C3I-L detects the excitation current of each phase of the servo motor Sv. As is well known, no matter what type of electric motor the servo motor Sv is constituted of, its power source is the magnetic field created by the excitation current 1. Therefore, by detecting the excitation current, the driving status of the servo motor 20 can be detected accurately and quickly.

In addition, the servo system that is monitored by the servo motor drive monitoring device already has a threefold feedback loop as a basic configuration (as mentioned above). A detection circuit that detects the excitation current as feedback information is an essential component of the loop that performs feedback control of the excitation current.Therefore, a separate detection circuit is prepared as the excitation current detection means C3 of the servo motor drive monitoring device. Instead, a detection circuit with the same function that is provided in advance in the current loop of the servo system may be used.

The detection results of the excitation current detection means C3 are stored in chronological order by the detection result storage means C4.The stored contents are outputted by the detection result output means C5 in response to a request from an external device. , the driving status of the servo system can be known in real time and extremely accurately, and accurate abnormality avoidance processing can be executed.

EMBODIMENT OF THE INVENTION Hereinafter, in order to more specifically explain the servo motor drive monitoring device of the present invention, it will be described in detail using examples.

[Example] Figure 2 (upper) is a hardware configuration diagram of a servo motor drive system that is also equipped with a servo motor drive monitoring device of an example.

As shown in the figure, the controller 101t is configured by a digital circuit centered on a microcomputer in consideration of the simplification and versatility of the configuration. It should be noted that configuring a triple feedback system, which will be described later, using only a single CPU and having it process the control as a servo motor drive monitoring device (it would be a heavy burden and would be undesirable in terms of responsiveness). In the embodiment, a high-speed CPU 10a is in charge of the function of a servo motor drive monitoring device and a current loop function, which require particularly high speed, and a normal CPU 10b is in charge of a position loop and a speed loop, which do not require high responsiveness. , the controller 10 is configured using two types of CPUs.

Therefore, it is necessary to closely communicate information such as target current value and abnormality monitoring results between the high-speed CPU 10a and the normal CPU 10b. In order to extract data, it is necessary to be able to execute it without being constrained by the normal CPU 10b, which has a slow operating speed.In order to easily and effectively satisfy this condition, in this embodiment, there is a dual port)-RAM (hereinafter referred to as DPRAM)
10c, each CPU achieves the purpose of communication by simply writing information necessary for communication into this DPRAMloc. In other words, each CPU is programmed to store information to be shared with other CPUs at a predetermined address in DPRAMloc, and the other CPU reads out the information stored at the predetermined address. Communication of information is performed without any restrictions on operating speed.

The rest of the configuration of the controller 10 is the same as that of a normal logic operation circuit, and includes a first ROM 10d that non-volatilely stores various control programs executed by the high-speed CPLJTOa.
, a second ROM 10e that non-volatilely stores various control programs executed by the normal CPIJlob, and a second ROM 10e that temporarily stores information and uses the high-speed CPLJloa and the normal CPU.
RAM 10f that assists the calculations of 10b, and an input/output board 1 that receives and receives information between these logic circuits and other devices.
0gt is the main component.

As the other equipment mentioned above, as an electric circuit for driving the servo motor 20, a PWM circuit 10h outputs a PWM signal according to a control signal inputted from the input/output port 10g, and a power transistor is configured based on the PWM signal. A driver 10j is provided to drive the power amplifier 10i. These devices output PWM-controlled three-phase alternating current from the power amplifier 70i, and control the input power of the servo motor 20 to a desired value.
Control signal output from 10g, that is, high-speed CPU1
It will be controlled by a logic circuit centered around 0a and CPU 10b.

Further, in order to control the controller 1013 and the servo motor 20 more accurately and stably, a feedback control method is adopted as usual. The information on the servo motor 20 that is fed back (including the detection output of the current detection coils 22 and 24 that measure the excitation current to detect the torque generated by the servo motor 20 and the rotation status (rotation position, This is the detection output of the encoder 26 that detects the rotational speed).

In the system configured as described above, the first ROM 10d and the second ROM 10e of the controller 10 include
A control program described below is stored to configure a normal servo system.

First, flowcharts of the programs stored in the second ROM 10e are shown in FIGS. 3 and 4. These programs are repeatedly executed from the time the controller 10 is started, and are 2m5 in Figure 3.
The ec interrupt routine is executed at 200 in Figure 4 every 2m5ec.
The μsec interrupt routine is repeatedly executed by interrupting the normal CPIJ 10b every 200 μSec.

When the processing of the 2mSec interrupt routine shown in FIG. Detection of (representing time) (
Step 100) is executed. Then, control target data 90 that instructs how to drive the servo motor 20 in this state next time is read from an external NC device (not shown) (step 110), and these data Xn,
Based on Dn, the feedback control system calculates the rotational position of the servo motor 20 by the following equation (step 120).

0X=AX (Dn-β1・Xn) In other words, the current rotational position Xn is added to the current control data Dn.
In order to calculate the deviation of the rotational position, the value (β1・Xn) obtained by multiplying the rotational position Xn by the feedback gain β1 is subtracted from the control data Dn. It is set as a variable OX. Here, the amplification degree AX and (upper proportional constant Pl and integral constant 1
1, and executes so-called P1 control.

Then, this latest calculation data ○X is stored in the RAM lOf (step 130), and this program is ended.

The variable OX ii calculated in this way and stored in the RAM 10f is used as follows in the 200 μSec interrupt routine shown in FIG. First, 200μSe
In the c interrupt routine (Top), in order to detect the driving state of the servo motor 20, the rotational position Xn is detected from the detection result of the encoder 26 (step 200), and the result is differentiated to calculate the rotational speed Vn (step 210). ).

Then, the latest variable Ox calculated in the above 2mSec interrupt routine is read from the RAM 10f (
Step 220), and based on these data, a negative feedback calculation for the rotational speed is performed using the following equation (Step 230).

○V: AV (○X-β2-Vn) Here, β2 represents the feedback gain. Further, AV is an amplification factor including a proportional constant β2 and an integral constant 2, and P1 control is executed in the same manner as described above. Then, the data ○V thus calculated is transferred to DPRAM.
loe at a predetermined address (step 240),
Exit this program.

Next, the first ROMI Odl second stored 60μse
The c-interrupt routine will be explained according to the flowchart shown in FIG. This program 1 is repeatedly executed by interrupting the high-speed CPU 10a every 60 μSec from the time when the controller 10 is activated.

When the processing of this program starts, the torque Tn is calculated by converting the detection results of the current detection coils 22 and 24, which are analog information, into digital information (step 3).
00), prepare for the following processing. And the above 200uS
The latest variable Ov calculated in the ec interrupt routine 2 and stored in DPRAMloc is read (step 310), and in order to negatively feed back the torque Tn detected in step 300 to this variable Ov, the following calculation is performed. Then, the final control signal OT is calculated (Stella 320).

0T=AT (○V-β3-Tn) Here, β3 represents a feedback gain -C.

Further, AT is an amplification factor including a proportional constant P3 and an integral constant 3. When the final control signal OT is calculated in this way, this control signal OT is transferred from the input/output port 10d to the PWM
The output signal is output to the circuit 10e (step 330), and a series of processing is completed.

To summarize the processing by the above three interrupt routines, +
f, as follows.

The deviation between the control target data Dn and the actual rotational position x n of the servo motor 20 is detected every 2m5ec, and the speed deviation is detected every 200μSec.The target excitation current value required to minimize these. Data ○V indicating . Since the excitation current control based on this data ○V requires high-speed execution, the data ○V is
By storing it in PRAMloc, you can easily increase the speed of the CPU.
The information is communicated to 10a.

And high speed CPU 10alt, DPRAM 10C
The data Ov is read in, the deviation of the current (torque) is detected every 60 μSec, and the excitation current of the servo motor 20 is PWM-controlled to minimize this deviation.

FIG. 6 is a diagram visually showing a pseudo electronic circuit configured as the controller 10 by the various programs described above (excluding the portion indicated by the dashed line). By executing the above various programs, high-speed CPU 10
a. A logic circuit composed of a normal CPU 10b or an input/output port 10g (as shown in the figure, a triple feedback circuit can be constructed).

Briefly, the amplification degree (transfer coefficient) It of the position amplifier 50a, speed amplifier 5ob, and current amplifier 50c that step-by-step amplify control target data Dn given to this servo system from an external device (not shown), and the high-speed CPU 1
0a or corresponds to a coefficient in a logical operation executed within the normal CPU 10b, the amplification degree of the position amplifier 50a is the coefficient AX of the above-mentioned step 120, and the amplification degree of the speed amplifier 50c is the coefficient AV of the above-mentioned step 230. , the amplification degree of the current amplifier 50d corresponds to the coefficient AT in step 320 described above. In addition, the feedback information of this servo system (as described above is the detection output of the current detection coil 22.24 and the encoder 26, but since the detection output of the current detection coil 22.24 is an analog output, the A/D converter 50d After being converted into digital information by It is also fed back to the input of the speed amplifier 50c via the differential factor S and the feedback gain β2.

The above is a general description of the servo control system of the controller 10, which is composed of logic circuits.

Furthermore, in this embodiment, a separate program for configuring a servo motor drive monitoring device centering on the high-speed cpUloa is stored in the first ROM 10dl of the controller 10 configured as described above, and this program can be activated. It is possible to monitor the driving status of the triple loop servo system configured as described above.

The separate programs stored in the first ROM 10d will be explained along the flowchart of FIG. 7, and the operation of the servo motor drive monitoring device constituted by the controller 10 of this embodiment will be explained in detail.

This servo motor drive monitoring routine is executed by the high-speed CPU 10.
This process is repeated at all times except when a is executing the above-mentioned 60 μSec interrupt routine. That is, processing continues at the maximum speed of the high-speed CPU 10a. First, when the processing of this servo motor drive monitoring routine is started, the current detection coil 22
．． Read the detected value of 24 and adjust the servo motor 2 from that value.
0 excitation current ia, ib@calculate (step 400)
.

The servo motor 20 of this embodiment has three excitation phases, and the excitation current 1a for two of these phases.

If b is detected, the excitation current IC of the remaining phases can be easily calculated. Therefore, in order to reduce the number of current detection coils used, in this embodiment, the remaining excitation current (the detected excitation current la) is used.

b (step 410).

When the detection of each phase excitation current of the servo motor is completed in this way, a history creation process of each phase excitation current is executed (step 4
20). Here, the history creation process (i) is to organize the past detection results of the excitation current for each phase over time, and by using this history, the maximum (i minimum value) etc. can be determined instantly.

Next, the driving status of the servo motor 20 is determined from the created history of the excitation current of each phase and the control target data Dn currently input to the controller 10 (step 430). As described above, the driving state of the servo motor 20 can be determined in real time and with high accuracy, even though the excitation current cannot be analyzed, based on the history of the excitation current of each phase. Then, the driving state (ideally, control target data D
should follow and match n. Therefore, by comparing the excitation current history and the control target data Dn, any drive that provides information for determining the quality of the servo system, such as the actual driving state of the servo motor 20 and the time delay, phase delay, steady-state deviation, etc. relative to the control target. It judges the situation.

After completing the determination of the driving status of the servo system to be monitored, the determination result is stored in a predetermined area of the DPRAMI O10c while ensuring correspondence with the current time (step 440), and one time of this program is executed. Complete the process. Then, on the high-speed CPU 10af, after the processing of this servo motor drive monitoring routine is completed, the above-mentioned 60μSec
When the interrupt routine processing is not necessary, execute the processing of this program again and complete the above processing in real time as much as possible.

That is, by executing the detailed servo motor drive monitoring routine shown in FIG.
A circuit indicated by a dashed line in the figure is added. Here, the drive monitoring section 50e in FIG. 6 is a simulated processing circuit that sequentially executes the processing shown in FIG. 7. Further, the driving status storage section 50f corresponds to a predetermined address area of DPRAMloc.

As is clear from the above explanation, the controller incorporating the servo motor drive monitoring device of this embodiment]O
The following effects are obvious.

Conventionally, in order to detect the driving status of the servo system, a torque sensor that detects the output torque of the servo motor 20 or a PWM
However, the servo motor drive monitoring device of this embodiment (current detection, which is an essential component of the servo system) is not required. Coil 22.24
By using the detection output of the servo system, we have achieved the detection of the driving status of the servo system.
It can be economically installed.

Moreover, since the driving status of the servo motor 20 is directly determined from the excitation current, high-speed determination in real time is possible, and instantaneous abnormality avoidance processing such as disconnection or short circuit of the excitation winding of the servo motor 20 is required. It is possible to deal with any situation sufficiently. This protects the semiconductor switching elements that make up the power amplifier 10i from overcurrent damage,
Control that requires quick response, such as protecting the excitation winding of the servo motor 20 from burnout, becomes possible. That is, when it is determined that an abnormality has occurred in the servo system by executing the servo motor drive monitoring routine, the PWM
It is possible to take measures such as stopping the operation of the circuit 10h or changing the gain of the position amplifier 50a to the current amplifier 50c to zero to control the excitation current of the servo motor 20 to zero.

In addition, since the servo system is monitored by detecting the excitation current of each phase of the servo motor 20, there is no room for detection errors or noise, and detection accuracy is dramatically improved compared to conventional methods. Reliability also increases.

Furthermore, in this embodiment, since the above-mentioned processing is performed using the high-speed CPU 10a, the above-mentioned characteristics can be further demonstrated, and even the instantaneous driving status of the servo system can be monitored in detail. High speed CPU10a and normal CPU+
Since the DPRAMloc is responsible for the information communication function with Ob, complicated control and circuits for communication are unnecessary, and the configuration can be simplified.

It should be noted that the servo motor drive monitoring device of the present invention is not limited to the above-mentioned configuration, and can be realized in various ways without departing from the gist of the invention. It is also possible to create a more economical configuration by configuring the system with good.

Effects of the Invention As described above in detail with reference to embodiments, the servo motor drive monitoring device of the present invention detects the excitation current of each phase of the servo motor and sequentially stores it.

Therefore, it is easy to install it together with the servo system to be monitored, and the overall structure can be small and economical.

Moreover, it has excellent responsiveness and reliability, and functions effectively even for emergency abnormality avoidance processing.

[Brief explanation of drawings]

FIG. 1 shows the basic configuration of the servo motor drive monitoring device of the present invention. FIG. 2 shows the blocks of the servo motor system incorporating the servo motor drive monitoring device of the embodiment. Figure 5 is a flowchart of the program processed by the controller of the same embodiment, Figure 6 is a block diagram of the pseudo electric circuit of the controller that is activated by the execution of the program, and Figure 7 is the servo motor drive monitoring of the same embodiment. 3 shows a flowchart of a program operating as a device.

Claims (1)

[Scope of Claims] 1. A power control circuit is interposed between a voltage source and a servo motor to control the amount of power supplied from the voltage source to the servo motor to bring the driving state of the servo motor to a target state. A servo motor drive monitoring device for monitoring a servo system that is subject to follow-up control, comprising: excitation current detection means for detecting the excitation current of each phase of the servo motor; and detection result storage for sequentially storing the detection results of the excitation current detection means. A servo motor drive monitoring device comprising: a detection result output means for outputting the stored contents of the detection result storage means in response to a request from an external device.