Motor control system

The invention is directed to omit an adjustment work of a motor control system and increase versatility. Provided is a motor control system including: an inverter which outputs a voltage to a motor based on a voltage command; a current detecting unit which outputs a current detection value based on a current flowing through the motor of a state quantity detecting unit; a voltage command calculating unit which outputs the voltage command of the state quantity detecting unit based on the high-order command and the current detection value of the state quantity detecting unit; a storage unit which outputs a data set of the quantity of state of the state quantity detecting unit based on the quantity of state of a driving target of the motor of the state quantity detecting unit; an abnormality degree calculation equation updating unit which outputs an abnormality degree calculation equation for computing the abnormality degree of the driving target of the state quantity detecting unit based on the data set of the state quantity detecting unit; an abnormality degree calculating unit which outputs the abnormality degree based on the quantity of state of the state quantity detecting unit and the abnormality degree calculation equation of the state quantity detecting unit; and a voltage adjusting unit which outputs an adjustment voltage for adjusting the voltage command of the state quantity detecting unit based on the abnormality degree of the state quantity detecting unit.

TECHNICAL FIELD

The present invention relates to a technique for improving versatility of a motor control system. Here, the motor control system is a system for controlling the motor in accordance with the specification of a target to be driven by the motor.

BACKGROUND ART

Motors and motor control systems for controlling the motors are widely applied as means to convert electric power into mechanical output, to fans, pumps, compressors, automobiles, railroads, for example. On the other hand, as a problem of the motor control system, a step-out caused by a sudden load torque (instability of motor speed and torque), vibration caused by pulsation load torque, and the like are known. As techniques for detecting and preventing these problems, there are PTLs 1 and 2.

In PTL 1, in order to detect the step-out caused by the sudden load, a motor current is Fourier-analyzed and its pulsating component is compared with a reference value. If a step-out occurs due to the sudden load torque, since the pulsating component of the motor current exceeds the reference value, it is possible to detect the step-out. Furthermore, by transmitting information on the loss of synchronization detection to a host controller, safety can be improved.

PTL 2 reduces vibrations due to the pulsation load torques. A rotor position is estimated from the motor current, and the pulsation load torque is estimated by substituting the position estimation value into the motion equation. Next, Fourier analysis is performed on the pulsation load torque, and the output voltage of the inverter is pulsed so as to cancel each frequency component. If the pulsation amount of the output voltage is appropriate, the motor torque and the pulsation load torque cancel each other out and the vibration is reduced.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

A common problem of PTLs 1 and 2 is the necessity of an adjustment work of the control parameters. For example, there are a reference value of a current pulsation component of PTL 1, an upper limit order of the Fourier analysis of PTL 2, and the like. When the reference value of the current pulsation component is set to a lower value, erroneous detection increases, and when the reference value is set to a high value, oversight is not overlooked. Also, when the upper limit number of Fourier analysis is set to a low value, the vibration cannot be suppressed, and when the upper limit is set to a high value, the calculation amount increases unnecessarily. Therefore, these control parameters need to be adjusted for each motor control system, and the development period is prolonged.

An object of the present invention is to omit the adjustment work of the motor control system and to increase versatility.

Solution to Problem

Features of the present invention for solving the above problem is as follows, for example.

Provided is a motor control system including: an inverter which outputs a voltage to a motor based on a voltage command; a current detecting unit which outputs a current detection value based on a current flowing through a motor of a state quantity detecting unit42; a voltage command calculating unit which outputs the voltage command of the state quantity detecting unit42based on a high-order command and the current detection value of the state quantity detecting unit42; a storage unit which outputs a data set of the quantity of state of the state quantity detecting unit42based on the quantity of state of a driving target of the motor of the state quantity detecting unit42; an abnormality degree calculation equation updating unit which outputs an abnormality degree calculation equation for computing the abnormality degree of the driving target of the state quantity detecting unit42based on the data set of the state quantity detecting unit42; an abnormality degree calculating unit which outputs the abnormality degree based on the quantity of state of the state quantity detecting unit42and the abnormality degree calculation equation of the state quantity detecting unit42; and a voltage adjusting unit which outputs an adjustment voltage for adjusting the voltage command of the state quantity detecting unit42based on the abnormality degree of the state quantity detecting unit42.

Advantageous Effects of Invention

According to the present invention, the adjustment work of the motor control system can be omitted, and versatility can be enhanced. The problems, configurations and effects other than those described above will be clarified by the description of the embodiments below.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. The following description illustrates concrete examples of the contents of the present invention, the present invention is not limited to these descriptions, and various changes and modifications made by those skilled in the art can be made within the scope of the technical idea disclosed in this specification. Further, in all the drawings for explaining the present invention, those having the same function will be denoted by the same reference numerals, and the repetitive description thereof may be omitted.

First Embodiment

A first embodiment will be described with reference toFIGS. 1 to 8.FIG. 1is a configuration diagram of a motor control system according to the first embodiment.

When three-phase AC voltages (a U-phase voltage Vu, a V-phase voltage Vv, and a W-phase voltage Vw) are applied to a motor1by an inverter2, three-phase AC currents (a U-phase current Iu, a V-phase current Iv, and a W-phase current Iw) flow, and a motor torque τ is generated.

A quantity of state of the motor1will be described.FIG. 2is a vector diagram of a voltage and a current. The U-axis represents a magnetic flux direction generated by a U-phase coil of the motor1. A d-axis is an axis advanced by the rotor phase θd from the U-axis (counterclockwise: advance, clockwise: delay) and rotates in a counterclockwise direction at a rotational speed ω of the motor1. A q-axis is an axis advanced by π/2 from the d-axis. A voltage vector V1is a vector representing the amplitude and phase of the three-phase AC voltage, and the phase thereof is advanced by the voltage phase δv with respect to the q-axis as a reference. The U-axis component, the d-axis component, and the q-axis component of the voltage vector V1are the U-phase voltage Vu, the d-axis voltage Vd, and the q-axis voltage Vq, respectively. The current vector I1is a vector representing the amplitude and phase of the three-phase alternating current, and its phase is advanced by the current phase δi with respect to the q-axis as a reference. The U-axis component, the d-axis component, and the q-axis component of the current vector I1are the U-phase current Iu, the d-axis current Id, and the q-axis current Iq, respectively. For example, when the motor1is a magnet motor, a motor torque τ of (Equation 1) is generated. In (Equation 1), Pm is the number of pole pairs, Ke is the induced voltage coefficient, Ld is the d-axis inductance, and Lq is the q-axis inductance.
[Equation 1]
τ=3/2Pm(Kc+(Ld−Lq)Id)Iq(Equation 1)

The above is a description of the quantity of state of the motor1.

The inverter2ofFIG. 1includes a main circuit21and a gate drive circuit22. The inverter2outputs a voltage to the motor1based on the voltage command. The gate drive circuit22outputs the gate signals Sup, Sun, Svp, Svn, Swp and Swn based on the final voltage command V** and the voltage phase δv. Here, the final voltage command V** is the length of the voltage vector V1ofFIG. 1. At this time, ON⋅OFF of the gate signals Sup to Swn can be determined by, for example, PWM (Pulse Width Modulation) The main circuit21converts the DC voltage VDC into three-phase alternating voltages Vu, Vv, and Vw by switching, and applies thy three-phase alternating voltages to the motor1.

The current detecting unit3outputs the detected value of the three-phase alternating current of the motor1. In other words, the current detecting unit3outputs the current detection value, based on the current flowing through the motor1. In order to simplify the description, it is assumed that the detection error is negligible, and the three-phase alternating current and its detection value are both denoted by symbols Iu, Iv, and Iw.

The driving target4is a system in which the motor1is used as a drive source. InFIG. 1, the driving target4is a compressor, and includes a cylinder41and a state quantity detecting unit42. The driving target4outputs one or more types of quantity of state p, and inFIG. 1, the driving target is a temperature, a pressure, a vibration, and the like of the compressor. Otherwise, for example, if the driving target4is a fan and a pump, the quantity of state p is a wind speed, a flow rate, and the like.

The voltage command calculating unit5outputs the voltage command V* based on the high-order command and the current detection value. The high-order command is a command given from a host control system to the motor control system, and is, for example, a speed command f* or a torque command τ*. Specifically, the voltage command calculating unit5is, for example, vector control or V/f control.

A storage unit6stores the quantity of state p and outputs the data set P thereof. A difference between the quantity of state p and the data set P is that the quantity of state p is an instantaneous value and does not have a history, whereas the data set P has a history.

An abnormality degree calculation equation updating unit7outputs an abnormality degree calculation equation f(p) based on the data set P. The abnormality degree calculation equation f(p) is an equation for calculating the abnormality degree An, and the abnormality degree An is an index which represents the degree of the quantity of state p deviates from the normal state of the driving target4. The normal state is a state in which the driving target4is in the most desirable state, for example, an operating state in which the driving target4can be driven with high efficiency and low vibration. When the quantity of state p is in the normal state, the abnormality degree An is zero, and as the quantity of state p deviates from the ideal state, the abnormality degree An increases.

For example, when the driving target4is a compressor, the compressor pressure is considered as the quantity of state p, and it is assumed that the normal state is a point A inFIG. 3(a). At this time, assuming that the current compressor pressure is a point B, the abnormality degree An is a distance between points A and B. The quantity of state p is not necessarily one kind, but a plurality of cases may be considered. For example, when p1is set as the compressor pressure and p2is set as the refrigerant flow rate, its normal state is the curve illustrated inFIG. 3(b). The reason that p1and p2are in a positive correlation is that the refrigerant flow rate increases as the compressor pressure increases. Here, assuming that the present quantity of state p is the point C, the distance between the curve and the point C is the abnormality degree An. In this case, since the refrigerant flow rate is lower than the compressor pressure, for example, it is expected that the refrigerant leaks from the piping. Thus, the abnormality degree An is an index for finding abnormality of the driving target4.

The abnormality degree calculating unit8outputs the abnormality degree “An=f(p)” based on the quantity of state p and the abnormality degree calculating formula f(p). InFIG. 3, the abnormality degree calculation equation f(p) is a linear distance between the normal state and the present quantity of state p, but it is not necessarily required to be a linear distance.

The voltage adjusting unit9outputs an adjustment voltage ΔV for adjusting the voltage command based on the abnormality degree An. The conversion from the abnormality degree An to the adjustment voltage ΔV is, for example, as illustrated inFIG. 4, and “ΔV=0 in An=0” is satisfied. Other characteristics are arbitrary, but as illustrated inFIG. 4, by limiting at the maximum output voltage Vmax of the inverter2, an abnormal operation of the inverter2can be prevented.

The constituent elements in the first embodiment are as described above. Characteristic units of the present invention will be described.

The characteristic unit of the present invention is feedback provided by the storage unit6, the abnormality degree calculation equation updating unit7, the abnormality degree calculating unit8, and the voltage adjusting unit9. When the driving target4is normal, the normal state illustrated inFIG. 3is learned by the storage unit6and the abnormality degree calculation equation updating unit7. When the normality and abnormality of the driving target4are unknown, the quantity of state p may be obtained by simulation simulating the driving target4. In other words, learning in the normal state is learning of the abnormality degree calculation equation f(p), and after the learning of the abnormality degree calculation equation f(p), the adjustment voltage ΔV is output by the abnormality degree calculating unit8and the voltage adjusting unit9. The feedback of the voltage adjusting unit9is different from the feedback of the voltage command operating unit5in the following points.

(1) Voltage command calculating unit5is feedback of the current detection value, that is, feedback of information on the motor1

(2) On the other hand, the voltage adjusting unit9is feedback concerning the information of the driving target4.

In order to detect the manufacturing error of the driving target4or the characteristic change during operation, feedback of the voltage adjusting unit9of (2) is indispensable. Conversely, by providing this, it is possible to omit the adjustment work of the motor control system and to enhance versatility.

The above description is about the characteristic units of the present invention. Next, the effects of the present invention will be described through specific examples at the time of starting the motor and at the time of pulsation load.

FIG. 5is a waveform diagram at the time of startup. InFIG. 5, the quantity of state p is a rotational speed of a fan and pump or the like. At time0, the motor1starts up. At time t1, due to an unexpected load, the quantity of state p decreases and the abnormality degree An increases. At time t2, the abnormality degree An exceeds 1, and at the same time, the voltage command calculating unit5resets the voltage command V* to zero in order to protect the driving target4. At time t3, the motor1is restarted, but the difference from the initial startup is that the adjustment voltage ΔV is set to 1 based on the abnormality degree An (=1) at time t2.

This is achieved, for example, as illustrated inFIG. 6, when the voltage adjusting unit9includes an abnormality degree and adjustment voltage conversion table91and a delay element92, and the abnormality degree and adjustment voltage conversion table91is as illustrated inFIG. 4(b). In other words, the voltage adjusting unit9outputs the adjustment voltage at least once based on the abnormality degree. Since the adjustment voltage ΔV is set to 1 after the time t3ofFIG. 5, the final voltage command V** increases to that extent. At this time, the voltage command V* is the same as the initial startup. At time t4, the quantity of state p decreases again due to an unexpected load, but the final voltage command V** is larger than at the time of the previous startup, the quantity of state p increases again, and the abnormality degree An does not exceed 1. At time t5, the quantity of state p reaches an equilibrium state. According to the configuration of the present invention, re-startup of the motor1can be automated in this way.

InFIG. 5, even if the storage unit6, the abnormality degree calculation equation updating unit7, the abnormality degree calculating unit8, and the voltage adjusting unit9are not provided, by setting the threshold value px for the quantity of state p, it is possible to perform the re-startup. However, due to the following problems, adjustment work of the threshold value px becomes complicated.

(1) The threshold value px varies depending on manufacturing errors of the motor1and the driving target4or characteristic changes during operation.

(2) Since there are a plurality of quantities of state p, there are also plural threshold values px.

(3) There is a case where abnormality of the driving target4cannot be determined only by the magnitude relation of the threshold value px. For example, there is a case of determining an abnormality by the distortion rate or frequency characteristic of the quantity of state p.

According to the configuration of the present invention, the problems of (1) to (3) above can be avoided, and re-startup of the motor1can be automated.

FIG. 7illustrates a waveform diagram during torque pulsation. InFIG. 7, the quantity of state p is the vibration amplitude of the compressor, and T is the cycle of the compressor. Since the load torque applied to the motor1by the compressor pulsates, at the time0to t1, the quantity of state p and the abnormality degree An are positive. At the time t1to t2, the voltage command calculating unit5pulses the voltage command V* in a sinusoidal wave form at the following amplitude and frequency in order to cancel the pulsation of the load torque and reduce the quantity of state p.

(1) Amplitude: the value obtained by converting the torque pulsation amplitude into the voltage amplitude, using the electrical characteristic of the motor1

(2) Frequency: same as the torque pulsation frequency (driving frequency of the compressor)

This can be achieved, for example, by using a vector control including the torque pulsation suppression control as the voltage command calculating unit5. As a result, the quantity of state p at times t1to t2is reduced as compared with time0to t1. However, since the pulsation of the load torque includes harmonic components, the quantity of state p does not become zero. Therefore, at the times t2to t3, the voltage adjusting unit9outputs the adjustment voltage ΔV including the harmonic to reduce the quantity of state p. Even after the time t3, the adjustment voltage ΔV is optimized by feedback of the state quantity detecting unit42, the storage unit6, the abnormality degree calculation equation updating unit7, the abnormality degree calculating unit8, and the voltage adjusting unit9, and the quantity of state p is reduced. At the time t4, the quantity of state p becomes zero, and the optimization of the adjustment voltage ΔV is completed. The adjustment voltage ΔV after optimization has the following characteristics.

(1) Amplitude: it is a harmonic, and becomes variable within the cycle T of the compressor.

(2) Frequency: same as the torque pulsation frequency (driving frequency of the compressor)

The difference between the voltage command V* and the adjustment voltage Δ is the amplitude of (1), the former being a sine wave and the latter being a harmonic. Since the final voltage command V** is generated by these sums, arbitrary torque pulsation can be canceled and the quantity of state p can be reduced.

InFIG. 7, even if the storage unit6, the abnormality degree calculation equation updating unit7, the abnormality degree calculating unit8, and the voltage adjusting unit9are not provided, by enhancing the responsiveness of the voltage command calculating unit5sufficiently, it is also possible to set the voltage command V* to a harmonic. However, due to the following problems, the work of adjusting the control parameters of the voltage command calculating unit5becomes complicated.

(1) The responsiveness of the required voltage command calculating unit5depends on the mechanical characteristics of the compressor.

(2) An improvement in responsiveness of the voltage command calculating unit5makes the motor control system unstable.

According to the configuration of the present invention, the problems of (1) and (2) above can be avoided, and the vibration of the compressor can be automatically reduced.

The above is the effect of the present invention. Furthermore, by changing the following units, its effect can be enhanced.

The abnormality degree calculation equation updating unit7outputs two or more abnormality degree calculation equations f(p), the abnormality degree calculating unit8outputs two or more abnormality degrees An, and the voltage adjusting unit9may control the adjustment voltage ΔV such that at least one other among the plurality of abnormality degrees is a minimum value in a range in which at least one of the plurality of abnormality degrees is a predetermined value or less. Thus, in a case where there is a trade-off relation between the plurality of abnormality degrees, the relation can be optimized.

For example,FIG. 8illustrates a waveform diagram when there are two degrees of abnormality. τL is a load torque, τL0is a load torque amplitude, τ0is a motor torque amplitude, An1is an abnormality degree related to the efficiency of the motor1, An1-max is an abnormality degree allowable maximum value, and An2is an abnormality degree related to the vibration of the driving target4. The abnormality degree allowable maximum value is an allowable maximum value of the abnormality degree An-1, and the control purpose here is to minimize the abnormality degree An2, while keeping the abnormality degree An1at the abnormality degree allowable maximum value An1-max or less.

At the times0to t1inFIG. 8, the load torque τL pulsates, meanwhile, the motor torque τ does not pulsate, and the rotational speed w of the motor1is pulsed by the differential torque. In this case, since the motor torque τ is constant, the d-axis current Id and the q-axis current Iq of (Equation 1) can be controlled to be constant and minimum. Thus, the copper loss of the motor1is minimized, and the abnormality degree An1becomes zero.

On the other hand, since the rotational speed w is pulsating, the abnormality degree An2is positive. When the storage unit6, the abnormality degree calculation equation updating unit7, the abnormality degree calculating unit8, and the voltage adjusting unit9are validated at the time t1, the adjustment voltage ΔV is generated. As a result, since the motor torque τ pulsates and the differential torque from the load torque τL becomes small, the pulsation of the rotational speed ωr and the abnormality degree An2also decrease.

On the other hand, since the d-axis current Id and the q-axis current Iq of (Equation 1) pulsate, the d-axis current Id and the q-axis current Iq become larger than a case where they are controlled to be constant and minimum, and the copper loss and the abnormality degree An1also increase. As described above, the abnormality degrees An1and An2are in a trade-off relationship, and as the abnormality degree An2is reduced, the abnormality degree An1increases. Then, at the time t2, the abnormality degree An1becomes equal to the abnormality degree allowable maximum value, and here, the optimization of the adjustment voltage ΔV is completed.

As described above, according to the configuration of the present invention, a trade-off between abnormality degrees can be automatically optimized. The type of abnormality increases as the size of the driving target4increases, and the trade-off relation between them becomes complicated, but the present invention is particularly effective in such a case.

The motor control system may be provided with a coupling unit11between the motor1and the driving target4, and may be provided with a learning mode in which the motor1and the driving target4are temporarily disconnected.FIG. 9illustrates a flowchart in the learning mode.

In the learning mode, the coupling unit11disconnects the motor1and the driving target4and connects the servo system instead. As a substitute for the driving target4, the servo system simulates all or a part of considered driving patterns. At this time, the storage unit6outputs a plurality of data sets P, and the abnormality degree calculation equation updating unit7outputs the abnormality degree calculation equation f(p) at least once. After the output, the motor1and the servo system are disconnected from each other, and the driving target4is reconnected instead. After reconnection, an abnormality degree An is calculated based on the abnormality degree calculation equation f(p) which is output at the time of the learning mode. By using such a learning mode, the following effects can be obtained.

(1) When the driving target4is a large-scale system and cannot be moved with an arbitrary operation pattern, the data set P can be acquired in a short time.

(2) It is possible to acquire the data set P of a less frequent operation pattern in the driving target4in advance.

As a result of the above, it is possible to shorten the period until the abnormality degree calculation equation updating unit7initially outputs the abnormality degree calculation equation f(p), and it is also possible to shorten the introduction period of the motor control system.

Instead of the data set of the quantity of state p, the storage unit6may output the data set of the quantity of state p and the current detection value. For example, it is assumed that the driving target4is a fan, the quantity of state p is the torque of the fan rotation shaft, and the current detection value is the amplitude |Iu| of the U-phase current Iu. At this time, the normal state is the straight line L as illustrated inFIG. 3(c). This is because the U-phase current amplitude |Iu| is in a proportional relation to the q-axis current Iq ofFIG. 2and the q-axis current Iq and the motor torque τ are in a proportional relation as indicated by (Equation 1). Assuming that the present quantity of state is the point D, the abnormality degree An is the distance to the straight line L. In this case, since the torque of the fan rotation shaft becomes smaller than the U-phase current amplitude |Iu|, for example, abnormalities, such as (1) the temperature of the motor1rises, the resistance value of the motor1increases, the efficiency of the motor1decreases, (2) the rotation shaft is loosened, and torque is not transmitted from the motor1to the fan, are considered. As described above, since the storage unit6outputs not only the data set of the quantity of state p but also the data set of the current detection value, it is possible to expand the abnormal range that can be found.

The storage unit6may output only the data set of the current detection value. For example, the normal state of the U-phase current amplitude |Iu| and the V-phase current amplitude |Iv| has an equivalent relation as illustrated inFIG. 3(d). This is because the difference between the U-phase current Iu and the V-phase current Iv is only the phase (deviation of 2π/3) and the amplitude is equal. Since the U-phase current Iu is larger than the W-phase current Iw on the assumption that the present quantity of state is at the point E, for example, abnormalities, such as (1) U-phase impedance is lowered due to partial dielectric breakdown (short circuit) of the motor1, and (2) the U-phase voltage Vu is smaller than the V-phase output voltage Vv due to manufacturing error of the inverter2, are considered. As described above, even in the case where the storage unit6outputs only the data set of the current detection value, it is possible to detect the abnormality and also it is possible to reduce the number of input ports and the data communication volume of the storage unit6. Accordingly, the cost of the storage unit6can be reduced.

The abnormality degree calculating unit8can enhance the accuracy of the abnormality degree An by outputting the abnormality degree An based on the data set P instead of the quantity of state p. That is, by incorporating the temporal change amount of the quantity of state p in the abnormality degree calculation, it is possible to detect a sudden abnormality, for example, an instantaneous power failure.

It is desirable that the update cycle of the abnormality degree calculation equation f(p) provided by the abnormality degree calculation equation updating unit7is longer than the calculation cycle of the abnormality degree calculating unit8. As a result, since the calculation load of the abnormality degree calculation equation updating unit7is reduced and the responsiveness of the adjustment voltage ΔV is not deteriorated, the omission effect of the adjustment operation is not deteriorated. This is because the abnormality detection speed of the driving target4depends on the calculation cycle of the abnormality degree calculating unit8, but does not depend on the content of the abnormality degree calculation equation f(p). In other words, the content of the abnormality degree calculation equation f(p) affects the abnormality degree detection accuracy of the driving target4, and the update thereof is unnecessary after the learning has been sufficiently completed. Therefore, it is desirable that the update cycle of the abnormality degree calculation equation f(p) provided by the abnormality degree calculation equation updating unit7is longer than the calculation cycle of the abnormality degree calculating unit8.

Second Embodiment

FIG. 10is a configuration diagram of a second embodiment. However, the same points as those of the first embodiment will be omitted. In the second embodiment, the voltage command calculating unit5has a structure of speed control type vector control, and includes a PI control unit511, a PI control unit512, a coordinate transforming unit521, a torque-current conversion unit53, and a motor model54.

The PI control unit511performs the PI control on the difference between the rotational speed command f* and the rotational speed ω to calculate the torque command τ*. The PI control unit512performs the PI control on the difference between the d-axis current command Id*, the q-axis current command Iq* and the d-axis current Id, the q-axis current Iq to calculate the d-axis current command Id** and the q-axis current command Iq**. The coordinate transforming unit521transforms the three-phase alternating currents Iu, Iv, and Iw into the d-axis current Id and the q-axis current Iq, using the rotor phase θd as illustrated inFIG. 2. As with the coordinate transforming unit521, the coordinate transforming unit522converts the d-axis voltage command Vd* and the q-axis voltage command Vq* into three-phase AC voltage commands Vu*, Vv*, and Vw*. The three-phase AC voltage commands Vu*, Vv*, and Vw* are converted into a voltage command V* and a voltage phase δv (FIG. 2), and are output from the voltage command calculating unit5. The torque-current conversion unit53converts the torque command τ* into a d-axis current command Id* and a q-axis current command Iq* by using (Equation 1). The motor model54is a model of the motor1, and converts the d-axis current command Id* and the q-axis current command Iq* into a d-axis voltage command Vd* and a q-axis voltage command Vq*.

According to the configuration ofFIG. 10, it is possible to independently control the d-axis component and the q-axis component of the motor1. As a result, since the non-interference control of the motor1is achieved, responsiveness to the speed command f* is improved. In particular, in the present invention, it is possible to provide a motor control system that is excellent in both responsiveness and robustness, by improving responsiveness through the voltage command calculating unit5and by improving robustness through the voltage adjusting unit9. Incidentally, instead of the speed control type, the same applies to the torque control type.

Third Embodiment

FIG. 11is a configuration diagram of the third embodiment. However, the same points as those of the first embodiment will be omitted. In the third embodiment, the voltage adjusting unit9adopts a constitution of integral calculation and includes a delay element92. In other words, the voltage adjusting unit9includes an integrating unit. The effect of this is as follows.

(1) It is possible to separate the responsiveness of the voltage command calculating unit5and the voltage adjusting unit9. That is, even if the voltage adjusting unit9is newly added to the existing voltage command calculating unit5, the response of the voltage command V* and the adjustment voltage ΔV do not interfere with each other, and the instability of the motor control system can be prevented.

(2) Robust against high frequency noise of the quantity of state p included in the abnormality degree An is achieved.

In this way, since the voltage adjusting unit9includes the integrating unit, it is possible to improve the robustness, without changing the existing motor control system. Although the responsiveness of the adjustment voltage ΔV is lowered, the responsiveness of the motor control system can be secured by the voltage command calculating unit5.

Fourth Embodiment

FIG. 12is a configuration diagram of a fourth embodiment. However, the same points as those of the first embodiment will be omitted. In the fourth embodiment, the abnormality degree calculation equation updating unit7includes a cluster classifying unit71, a cluster center-of-gravity position calculating unit72, and an abnormality degree calculation equation calculating unit73, and has the function of vector quantization clustering as a whole.

The cluster classifying unit71classifies the data set P into the respective clusters based on the cluster center of gravity X, and outputs the classification result Q thereof.FIG. 13illustrates an example of the cluster classification. P[1] and P[2] and P[3] represent a part of the data set P, X1, X2and X3represent cluster centers of gravity, and C1and C2represent the clusters. Since the data P[1] and P[2] are close to the cluster center of gravity X1, they are classified into the cluster C1. On the other hand, since the data P[3] is close to the cluster center of gravity X2, it is classified into the cluster C2. Therefore, the classification result Q relating to the data P[1] to [3] is “P[1]∈C1, P[2]∈C1, P[3]∈C2”.

The cluster center-of-gravity position calculating unit72recalculates the position of the cluster center of gravity X and outputs it. For example, inFIG. 13, only the P[1] and P[2] are included in the cluster C1, and the center of them is taken as a new center of gravity X1. Since the cluster center-of-gravity position calculating unit72outputs the position of the new center of gravity X to the cluster classifying unit71, the cluster classifying unit71performs the cluster classification again. By repeating the cluster classification, the position of the cluster center of gravity X becomes a position suitable for representing the dispersion situation of the data set P.

The position of the new center of gravity X is also output to the abnormality degree calculation equation calculating unit73. The abnormality degree calculation equation calculating unit73outputs the abnormality degree calculation equation f(p) with respect to a certain quantity of state p by setting the distance from the center of gravity X which is the shortest distance as the abnormality degree An. That is, the abnormality degree calculation equation f(p) is as follow.
[Equation 2]
f(p)=min(r(p,X1),r(p,X1), . . . ,r(p,Xn))  (Equation 2)

Here r: distance calculation equation, Xn: nth center of gravity.

The distance calculation equation r (p, Xn) is defined by, for example, a linear distance in orthogonal coordinates.

The effects of the above configuration are as follows.

(1) If the data set P is sufficient, the cluster center of gravity X is automatically calculated by the cluster classifying unit71and the cluster center-of-gravity position calculating unit72. Further, it is possible to quantitatively define the distribution of the data set P, that is, the state when the driving target4is normal, by the cluster center of gravity X.

(2) Based on the cluster center of gravity X, it is possible to detect the change in distribution of the data set P, that is, the occurrence of abnormality of the driving target4.

In this way, by including the cluster classifying unit71, the cluster center-of-gravity position calculating unit72, and the abnormality degree calculation equation calculating unit73, it is possible to detect the occurrence of abnormality of the driving target4, without requiring any adjustment work.

REFERENCE SIGNS LIST

1: motor2: inverter3: current detecting unit4: driving target41: cylinder42: state quantity detecting unit5: voltage command calculating unit6: storage unit7: abnormality degree calculation equation updating unit8: abnormality degree calculating unit9: voltage adjusting unit11: coupling unit21: main circuit22: gate drive circuit53: torque-current conversion unit54: motor model71: cluster classifying unit72: cluster center of gravity position calculating unit73: abnormality degree calculation equation calculating unit91: abnormality degree and adjustment voltage conversion table92: delay element511: PI control unit512: PI control unit521: coordinate transforming unit522: coordinate transforming unit