JP2001190099A - Vector control method of permanent magnet synchronous motor - Google Patents

Vector control method of permanent magnet synchronous motor

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Publication number
JP2001190099A
JP2001190099A JP2000031205A JP2000031205A JP2001190099A JP 2001190099 A JP2001190099 A JP 2001190099A JP 2000031205 A JP2000031205 A JP 2000031205A JP 2000031205 A JP2000031205 A JP 2000031205A JP 2001190099 A JP2001190099 A JP 2001190099A
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Prior art keywords
permanent magnet
current
control
vector
rotor
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JP3735836B2 (en
Inventor
Shinji Aranaka
新二 新中
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C & S Kokusai Kenkyusho:Kk
有限会社シー・アンド・エス国際研究所
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Abstract

(57) Abstract: The present invention relates to a control method of a permanent magnet synchronous motor, and a drive control using a magnetic pole position estimator or a magnetic pole position detector that can involve a detection error in specifying a rotor magnetic pole position. Provided is a vector control method for a permanent magnet synchronous motor, which provides a system with a function of increasing its stability and can easily realize this function. SOLUTION: The d-axis of the orthogonal dq coordinate system is selected in the direction of the center of the north pole of the rotor permanent magnet of the permanent magnet synchronous motor or in the estimated direction, and the d-axis current command is set according to the rotor speed and the torque command value. A new command converter 9 capable of simultaneously changing the value and the q-axis current command value is prepared, and a q-axis current command generator 9b is provided.
By causing the d-axis current command generator 9a to generate a positive d-axis current command value according to the absolute value of the rotor speed, while generating a q-axis current command value in a form proportional to the torque command value. This solves the problem by controlling the armature current so that the absolute value of the spatial phase difference of the current vector with respect to the center of the rotor magnetic pole N-pole becomes less than π / 2 (rad).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vector control method for a permanent magnet synchronous motor. In particular, the present invention relates to a vector control method using a magnetic pole position detector or a magnetic pole position / velocity estimator that may involve a detection error in detecting or estimating a magnetic pole position of a rotor permanent magnet.

[0002]

2. Description of the Related Art In order for a synchronous motor to exhibit high control performance, armature current control is indispensable, and a vector control method has been conventionally known as a control method for this purpose. The vector control method includes a current control step of dividing and controlling all or a part of the armature current into a d-axis component and a q-axis component on a dq coordinate system including a d-axis and a q-axis orthogonal to each other. Have. Normally, all of the armature current is represented by the d-axis component and q
It is divided into axis components and controlled. In the case of a special motor that is strongly affected by iron loss in the armature, the armature current is calculated by subtracting the equivalent iron loss current corresponding to the iron loss from the armature current, that is, a part of the armature current. On the other hand, the control may be divided into a d-axis component and a q-axis component.

As a dq coordinate system at this time, it is general to employ a synchronous coordinate system synchronized with the center of the north pole of the rotor permanent magnet with a spatial phase difference of zero. That is, it is general to adopt a synchronous coordinate system in which the same direction as the center line of the N pole of the rotor permanent magnet is selected as the d-axis, and the axis orthogonal thereto is selected as the q-axis. In order to maintain the dq coordinate system in a synchronized state with no spatial phase difference with the center of the rotor permanent magnet N pole, it is necessary to know the position of the center of the rotor permanent magnet N pole. In order to know this accurately, a position detector such as an encoder is traditionally mounted on the rotor. For applications where the position detector cannot be used, a magnetic pole position / velocity estimator that estimates the magnetic pole position is used instead.
Attempts have been made to maintain the configuration of the coordinate system.

FIG. 11 shows a typical example in which a vector control method using a magnetic pole position / velocity estimator instead of a position detector is implemented and mounted on a standard permanent magnet synchronous motor which can ignore iron loss. Is schematically shown in a block diagram. 1 is a permanent magnet synchronous motor, 2 is a current detector,
3 is a power converter, 4 is a magnetic pole position / velocity estimator, 5a,
5b is a three-phase to two-phase converter and a two-phase to three-phase converter, respectively, 6a,
6b is a vector rotator, 7 is a current controller, and 8 is a command converter. In FIG. 11, various devices from 4 to 8 constitute a vector control device.

In particular, the magnetic pole position / velocity estimator 4 estimates the center of the north pole of the rotor permanent magnet as an angle with respect to the center of the U-phase winding and outputs its cosine and sine signals. It constitutes means for determining the phase. In the case of a permanent magnet synchronous motor, the rotor speed is nothing but the rotation speed of a permanent magnet integrally mounted on the rotor. That is, the rotor magnetic pole position and the rotor speed have an integral and a derivative relationship with each other, and as is well known to those skilled in the art, not only when using a detector such as an encoder but also when using an estimator, At the same time, it obtains position and speed information. In the case of the present example using an estimator, a rotor speed estimated value is generally obtained simultaneously with a magnetic pole position estimated value,
In this example, the output of the estimated speed value is not shown due to the introduction of one example of the torque control that does not particularly require the speed information of the rotor. The three types of devices 5a, 5b, 6a, 6b, and 7 divide the armature current into a d-axis component and a q-axis component on a dq coordinate system so that each follows the d-axis and q-axis current command values. This constitutes means for executing a current control step of controlling. The device 8 constitutes a means for generating a q-axis current command value required for current control from the torque command value.

The three-phase current detected by the current detector 2 is 3
After being converted into a two-phase current on the fixed ab coordinate system by the phase-two-phase converter 5a, it is converted into two-phase currents id and iq on the dq coordinate system by the vector rotator 6a and sent to the current controller 7. The current controller 7 generates voltage command values vd *, vq * on the dq coordinate system so that the converted currents id, iq follow the respective current command values id *, iq *, and sends them to the vector rotator 6b. 6
In b, the two-phase signals vd * and vq * are converted into a two-phase voltage command value in a fixed ab coordinate system and sent to the two-phase three-phase converter 5b. In step 5b, the two-phase signal is converted into a three-phase voltage command value, which is output to the power converter 3 as a command value. Power converter 3
Generates electric power according to the command value, applies the electric power to the permanent magnet synchronous motor 1 and drives it. The current command value at this time is
For the d-axis current command value id *, a negative or zero constant value is directly given, and for the q-axis current command value iq *, the torque command value τ * is converted linearly through the command converter 8 using I have. The magnetic pole position / velocity estimator 4 constituting the means for determining the spatial phase of the dq coordinate system uses the voltage command value on the dq coordinate system, the d-axis component of the current, and the q-axis component to determine the rotor position. The magnetic pole position is estimated and the cosine and sine signal (co
s and sin signals) are output to the vector rotators 6a and 6b.

[0007]

In the conventional vector control method, the respective current command values applied in controlling the d-axis component and the q-axis component of the armature current are, as described in the above representative example, For the q-axis current command value, while generating a positive or negative value according to the positive or negative torque command value,
The d-axis current command value has a negative or zero value without exception.

[0008] The electric motor is a torque generator,
It is also an energy converter that converts electrical energy into mechanical energy. To efficiently perform energy conversion, it is desirable to reduce losses such as copper loss of the stator.
Further, in order to reduce the size of the driving inverter, it is desirable to improve the power factor of the electric power applied to the electric motor.
In order to reduce the loss and improve the power factor, the d-axis current needs to be kept negative or zero in any of the cylindrical and salient-pole permanent magnet synchronous motors.

A unified theory for minimizing loss and improving the power factor of permanent magnet synchronous motors including cylindrical and salient pole types is described in the literature (Shin-China Shinji, Efficient Current Control of Salient-Pole Synchronous Motors for Current Control). Analysis by vector signal, IEEJ Transactions D, V
ol. 119-D, No. 5, pp. 948-658)
Has been given to. For detailed quantitative analysis limited to salient-pole permanent magnet synchronous motors, see the literature (Morimoto, Oyama, Fujii, PM motors and drive systems with reluctance torque, National Institute of Electrical Engineers of Japan, 1996, Conference Papers 3, s11
8-s123). An explanation limited to the cylindrical permanent magnet synchronous motor is given in the literature (Sugimoto, Koyama, Tamai, Theory and Design of AC Servo System, Sogo Denshi Shuppan, p. 74). These state of the art claims that the d-axis current is controlled to be negative or zero.

In the prior art based on clear analysis results, when the position of the rotor magnetic pole can be accurately grasped by the position detector, an optimum result is obtained in control performance such as loss reduction and power factor improvement. However, in a situation where an accurate position detector cannot be used and the magnetic pole position must be estimated by a magnetic pole position / speed estimator instead,
It does not always provide the optimum performance, but conversely has the risk of lowering the overall performance.

When using a magnetic pole position / velocity estimator,
The estimated magnetic pole position can always have an error. Regarding the estimated magnetic pole position as the true magnetic pole position despite the existence of the error, the current command value determined according to the control purpose such as the loss reduction and the power factor improvement has no guarantee to achieve the control purpose. Conversely, in the low speed region, the voltage level is low, so that the voltage signal S
The / N ratio decreases, and phenomena such as an increase in the estimation error of the magnetic pole position, a decrease in the generated torque, and a decrease in the speed are repeated in a short time, and an unstable state, that is, an uncontrollable state may occur in a short time. This phenomenon is particularly conspicuous when the ripple of the external force acting on the motor rotor against the generated torque is large and changes rapidly. The most important control performance in the vector control method of the synchronous motor is to ensure stability, that is, to be able to generate torque stably. Other control performance is only when stability can be secured,
It is worth pursuing.

SUMMARY OF THE INVENTION The present invention has been made under the above background, and has as its object to easily destabilize a drive control system using a magnetic pole position velocity estimator or a magnetic pole position detector which may involve a detection error. In other words, it is an object of the present invention to provide a vector control method for a permanent magnet synchronous motor that can provide a drive control system with a new function that enhances its stability and that can easily realize the new function.

[0013]

In order to achieve the above object, the invention according to claim 1 is to provide a system in which all or a part of the armature current is expressed on a dq coordinate system composed of a d-axis and a q-axis orthogonal to each other. A current control step of dividing and controlling a current vector as a d-axis component and a q-axis component of a current vector, wherein the current control step includes the step of controlling the rotor permanent magnet in at least a part of the speed range. Controlling the armature current so that the current vector exists in a phase difference region where the relationship between the spatial phase difference of the current vector with respect to the center direction of the magnet N pole and the rotor generated torque is monotonically increasing. Features.

According to a second aspect of the present invention, there is provided the vector control method for a permanent magnet synchronous motor according to the first aspect, wherein the d axis of the dq coordinate system is oriented in the direction of the center of the rotor permanent magnet N pole of the permanent magnet synchronous motor. Alternatively, d is selected in this estimation direction, and d is used for controlling the d-axis component of the current vector in the current control step.
By making the axis current command value a positive level, the absolute value of the spatial phase difference of the current vector with respect to the center of the N pole becomes π
The armature current is controlled so as to be less than / 2 (rad).

According to a third aspect of the present invention, in the vector control method for a permanent magnet synchronous motor according to the first aspect, in the current control step on the dq coordinate system, when the speed is zero,
The armature current is controlled so that the current vector is present at the center of the monotonically increasing phase difference region.

Next, the operation of the present invention will be described. To properly understand the operation of the present invention, it is essential to understand the torque generation mechanism of the permanent magnet synchronous motor. For the sake of simplicity, the mechanism of torque generation will be described by taking drive control of a cylindrical synchronous motor having one pole pair without loss of generality as an example.

The orthogonal dq in the two-dimensional space shown in FIG.
Consider a coordinate system. The direction from the main axis d axis to the auxiliary axis q axis, that is, the counterclockwise direction is defined as a positive direction, and the reverse clockwise direction is defined as a negative direction. In this figure, the relationship between the center of the magnetic pole N-pole of the rotor and the dq coordinate system is shown in a general state. The magnetic flux vector by the rotor permanent magnet defined on the dq coordinate system is φ, and the current vector of the armature is i.
Since the magnetic flux vector is a magnetic flux generated by the rotor permanent magnet, the direction of the magnetic flux vector is the same as the center direction of the rotor permanent magnet N pole from the origin of the coordinates, as shown in FIG. The direction of the current vector differs depending on the direction of the torque to be generated, and the example of FIG. 1 shows a state where the torque is generated in the positive direction. As shown in the figure, assuming that the spatial phase difference of the current vector with respect to the center direction of the rotor permanent magnet N pole, that is, the magnetic flux vector is θ, the generated torque τ
Is expressed by the following equation (1).

(Equation 1) That is, when the magnitudes of the magnetic flux and the current are constant, the generated torque of the cylindrical synchronous motor is proportional to the sine value of the spatial phase difference θ.

This relationship can be illustrated as in FIG. FIG. 2 also shows a case where the spatial phase difference θ is negative, that is, the generated torque is negative (clockwise). As is clear from FIG. 2, the generated torque has a spatial phase difference of -π / 2 (r
From ad) to + π / 2 (rad), a monotonically increasing characteristic is shown, which monotonically increases in accordance with the spatial phase difference. Conversely,
The spatial phase difference is from -π (rad) to -π / 2 (ra
d) and in the range from + π / 2 (rad) to + π (rad), the generated torque exhibits a monotonically decreasing characteristic that monotonically decreases according to the spatial phase difference.

The direction of the external force acting on the motor rotor is generally opposite to the direction of the torque generated by the rotor. When viewed in the power running / regeneration state of the electric motor, the external force acts in a direction opposite to the rotation direction of the rotor in the power running state, and acts in the same direction as the rotation direction of the rotor in the regeneration state. That is, the external force acts on the motor rotor so as to oppose the torque generated by the rotor. This characteristic can be restated as that the external force acts in a direction to increase the spatial phase difference of the current vector with respect to the center direction of the rotor permanent magnet N pole. The characteristic that the external force acts on the rotor in a direction that increases the spatial phase difference of the current vector with respect to the center of the N pole is the same in both forward rotation and reverse rotation. .

In the conventional control method that emphasizes efficiency, the current vector is generated so that the maximum torque is generated. For example, in the examples of FIGS. 1 and 2, the absolute value of the spatial phase difference becomes π / 2 (rad). The phase difference was controlled. In the control method that emphasizes the power factor, the current vector is controlled so that the absolute value of the spatial phase difference is equal to or more than π / 2 (rad) so that the power factor is maximized. Even if the external force acting in the direction that increases the spatial phase difference increases in a short time due to ripples, etc., if the rotor magnetic pole position can always be accurately grasped, the spatial phase difference is controlled by the next instantaneous control. The increase could be corrected and the control objective could be stably achieved.

However, if there is an error in grasping the position, for example, by estimating the position of the rotor magnetic pole, even if the spatial phase difference is increased in a short time due to an external force, this increase in the spatial phase difference is not necessarily accurate. And cannot grasp quickly. Therefore, the absolute value of the spatial phase difference is, for example, π /
In the case where a control method in which the torque is present in a monotonically decreasing region including a critical point of 2 (rad) or more is employed, the generated torque is immediately reduced due to an increase in the spatial phase difference. When the reduction of the rotor generated torque is induced, the relative difference between the external force torque acting in the opposite direction and the rotor generated torque increases, and as a result, the spatial phase difference is further increased, and the motor generated torque is further increased. Level suddenly drops and suddenly falls into a state where torque cannot be generated.

Although the relationship between the generated torque and the spatial phase difference under the condition that the magnitude of the current vector is constant shown in FIG. 2 is that of the cylindrical synchronous motor, the salient-pole synchronous motor has the same monotone increasing region. It has a torque generation characteristic of being divided into two in a monotonically decreasing region. For example, when the number of pole pairs is 1, this torque generation characteristic can be expressed by the following equation.

(Equation 2) In the case of a salient-pole synchronous motor using a permanent magnet, the inductance Lb is negative due to the reverse salient pole characteristics. As is clear from equation (2), in the salient-pole synchronous motor, the monotonically increasing region is -π / 2 (ra) centered on zero (rad).
It is clear that the range from d) to + π / 2 (rad) is wider, and the width of the monotonically increasing entire region is wider than π (rad). On the other hand, it is also apparent that the entire area width of the monotonically decreasing area is smaller than π (rad). As is clear from the fact that the cylindrical and salient pole type synchronous motors have similar two-part torque generation characteristics of a monotonically increasing region and a monotonically decreasing region,
Regarding the generation of torque of the salient-pole synchronous motor, the description of the instability phenomenon described above holds true.

According to the control method of the first aspect, the current vector is a phase difference region where the relationship between the spatial phase difference of the current vector with respect to the center direction of the rotor permanent magnet N pole and the rotor generated torque is monotonically increasing. Since the armature current is controlled so as to exist within the range, for example, in the example of FIG. 2, the armature current is changed from -π / 2 (rad) to + π / 2 (ra) within the monotonically increasing region.
d) control to be within the spatial phase difference,
As a result, even if the spatial phase difference is suddenly increased by the external force and the increase in the spatial phase difference cannot be accurately grasped,
The torque generated by the motor increases instantaneously due to the monotonically increasing characteristic in accordance with the increase in the spatial phase difference, and thus an effect of being able to withstand an unexpected increase in external force is obtained.

According to a second aspect of the present invention, there is provided the vector control method according to the first aspect, wherein the d axis of the dq coordinate system is set in the center direction of the rotor permanent magnet N pole of the permanent magnet synchronous motor or in the estimated direction. Then, the d-axis current command value for controlling the d-axis component of the current vector in the current control step is set to a positive level. Since the d-axis current is controlled by the current control so as to match the command value, if the d-axis current command value is a positive level, the d-axis current also has the same positive level.
As a result, there is an effect that the armature current control such that the absolute value of the spatial phase difference of the current vector with respect to the center of the N pole of the rotor permanent magnet becomes less than π / 2 (rad) can be easily performed. can get. FIG. 3 shows an example in which the d-axis of the dq coordinate system is selected in the direction of the center of the north pole of the rotor permanent magnet and the d-axis current takes a positive level value. b) The case where negative (reverse) torque is generated is shown separately. As shown in the figure, when the d-axis current is positive, the absolute value of the spatial phase difference is π / 2 regardless of whether positive or negative torque is generated.
It is understood that the effect of being less than (rad) is obtained. As already described in detail, in any of the cylindrical and salient-pole permanent magnet synchronous motors, the monotonically increasing region deeply related to the present invention has a spatial phase difference of -π / 2 (ra).
The range from d) to + π / 2 (rad) is always included.

As is apparent from the above description, according to the second aspect of the present invention, the d axis of the dq coordinate system is selected to be the center direction of the rotor permanent magnet N pole of the permanent magnet synchronous motor or the estimated direction. After that, by simply setting the d-axis current command value for controlling the current vector d-axis component to a positive level, an effect is obtained that the current vector can be easily made to exist in the monotonically increasing region. As a result, it is possible to easily secure the action against sudden sudden increase of the external force described in claim 1.

According to a third aspect of the present invention, in the vector control method according to the first aspect, in the current control step on the dq coordinate system, the current vector is monotonically increasing in a state of zero speed. Since the armature current is controlled so as to be present at the center of the phase difference region, as is clear from the torque generation characteristic example of FIG. 2, the highest instantaneous drag against an unexpected instantaneous increase of the external force is obtained in the state of zero speed. The effect that it can be provided is obtained.

[0027]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 4 shows a basic structure of an embodiment of a vector control device and a permanent magnet synchronous motor to which the vector control method of the present invention is applied. 4 are the same as those of the conventional control method of FIG. 11, and the new command converter 9 is used in place of the conventional command converter 8 based on the present invention. I have. That is, the magnetic pole position / velocity estimator 4 used in the present embodiment is different from the magnetic pole position / velocity estimator 4 shown in FIG.
This is a conventional estimator itself which estimates the center of the north pole of the rotor permanent magnet as an angle with respect to the center of the U-phase winding and outputs its cosine and sine signals.

When the cosine and sine signals generated by the conventional magnetic pole position / velocity estimator 4 are used for the vector rotators 6a and 6b, the d axis of the orthogonal dq coordinate system is basically in the direction of the center of the rotor N pole. Will be oriented. That is, the relative positional relationship of the dq coordinate system with respect to the center of the rotor N pole is:
Basically, the state shown in FIG. 3 is pursued. As a matter of course, since the magnetic pole position estimated value by the magnetic pole position speed estimator has an error, the d axis does not always coincide exactly with the center of the rotor N pole.

In this embodiment, the magnetic pole position / speed estimator 4
, The rotor speed estimated value which can be generally generated simultaneously with the magnetic pole position estimated value is also output. As is clear from the figure, this embodiment shows a state in which speed control is finally performed using a permanent magnet synchronous motor whose torque is basically controlled by the vector control method. That is, the speed control system is configured outside the current control system based on the vector control method in order to perform the speed control. The speed controller 10 receives a deviation between a speed command value ω * given from the outside and an estimated value ωe of the rotor speed, which is one of the output signals of the magnetic pole position speed estimator 4. The speed deviation is subjected to processing such as P (proportional) control or PI (proportional integration) control in the speed controller 10, and the final processed signal is output to the new command converter 9. In the present embodiment, the new command converter 9 receives the rotor speed estimated value ωe from the magnetic pole position speed estimator 4 in addition to the output signal of the speed controller 10, and receives the d-axis current command value and the q-axis current command. The value is generated and output together.

In the present embodiment, the new command converter 9 is according to the present invention, and forms the center of the embodiment. Hereinafter, the new command converter 9 will be described in detail, clearly, and specifically. FIG. 5 shows an example of the internal configuration of the new command converter 9. 9a denotes a d-axis current command generator, and 9b denotes a q-axis current command generator. In the example of FIG. 5, the q-axis current command generator 9b is the same as the conventional command generator 8 of FIG. On the other hand, the d-axis current command generator 9a
The rotor speed estimation value is received as an input, and a positive command value is output in response thereto. FIG. 6 shows an example of the output characteristics of the d-axis current command generator 9a in FIG. The output characteristics are based on the absolute value of the input rotor speed estimate.
It shows the relationship between the output d-axis current command value,
This characteristic can be freely set by the designer.

The output characteristics freely set by the designer are as follows. First, the output characteristics are stored in a table at appropriate speed intervals, and then the output characteristics at intervals not stored are converted from the stored values to the absolute value of the estimated speed value. By approximating the d-axis current command generator 9a as an approximate polynomial, the desired output characteristics can be easily provided. In other words, the d-axis current command generator 9a, although approximately, follows the desired output characteristics.
A shaft current command value can be generated.

As the order of the above polynomial for approximation, 0th order, 1st order, 2nd order and 3rd order are realistic. In other words, the order of the approximate polynomial is practically sufficient up to the third order. For simple calculations, 0-order approximation and 1st-order approximation are appropriate. Next, the approximation method will be specifically described with reference to the output characteristics shown in FIG.

In the example of FIG. 6, the absolute value of the estimated rotor speed is substantially constant from zero to ω1, is substantially linearly attenuated from ω1 to ω2, and is substantially constant after ω2. If the absolute value of the rotor speed estimated value is zero to ω1 and the d-axis current command value from ω1 is id1 and the d-axis current command value after ω2 is id2, this characteristic example is approximated by the following equation. Can be expressed.

(Equation 3) As a polynomial approximation for the absolute value of the speed estimation value, (3
a) and (3c) are approximations by the 0th order, and (3b) is 1
The following approximation is performed. A method of dividing the output characteristic set by the designer into smaller pieces and approximating the output characteristics using a large number of approximation functions, or a method of partially approximating the section with a higher-order quadratic function and a cubic function is one example of the above example. Should be extended.
Since this can be easily understood by those skilled in the art from the above description, the description is omitted.

In practice, it is preferable that the output characteristics thus set are realized by software. FIG.
In order to contribute to software realization, the above processing is represented by a flowchart. That is, once the estimated speed value ωe is obtained, the absolute value is first determined in s1. Next, in s2, it is determined whether or not the absolute value of the speed estimation value is smaller than ω1, that is, (3a)
It is determined whether or not the expression is a target, and if true, the process proceeds to s3, and the processing of expression (3a) is performed. If false, proceed to the determination of s4, and compare the absolute value of the speed estimation value with ω2 to determine whether it is the target of equation (3b). If true, proceed to s5 and perform the processing of equation (3b). . If the determination in s4 is false, the process proceeds to s6 (3
c) Perform the processing of the equation. The d-axis current command generator 9a
By performing the processing shown in this flowchart in real time in accordance with the drive control of the synchronous motor, the desired output characteristics are achieved.

In the example shown in the above equation, the output characteristics are approximated in three regions by the speed of the rotor. Therefore, in the flow chart of FIG. 7 corresponding to this, two speed judgments s2 and s4 are performed.
And three processes s3, s5, and s6 were required. When the output characteristics are approximated by dividing them into n regions, (n-1)
Times of speed determination and n processes are required. The creation of the flow chart in this case is the same as that of FIG. 7, and the judgment and processing steps may be sequentially extended in a similar manner in accordance with the increase in the divided area. This will be obvious to those skilled in the art, and further description will be omitted.

As described above, as a d-axis current command generation method performed by the d-axis current command generator 9a, a method of generating a d-axis current command value according to an output characteristic approximated by a low-order function will be described using one example. explained. It should be pointed out that the method of approximating the output characteristics described above with a low-order function is only one example of the command current generation method performed by the d-axis current command generator 9a. Among the current command generation methods performed by the d-axis current command generator, the simplest method is to hold the d-axis current at a positive constant value in all speed ranges shown in the following equation (4). There are methods that have also been experimentally proven to be useful.

(Equation 4)

It is also pointed out that the output characteristic can be expressed by a single function that is monotonically decreasing with respect to the speed estimation value. A useful function for this is given by the following equation (5).

(Equation 5)

In the embodiment shown in FIG. 5, a zero speed is given as the speed command value, and when the rotor speed is controlled to substantially zero, the speed deviation, which is the difference between the two signals, is, of course, substantially zero. Becomes zero. Since the speed of the rotor is controlled using the estimate, it is not always exactly zero, but it can be zero, or substantially zero, within an acceptable error range. In the case where the speed deviation is substantially zero and the speed controller 10 is performing the P (proportional) control, the q-axis current command value is also substantially zero. In this case, the current vector has only the d-axis current component, and as is clear from FIG. 3, the spatial phase difference between the current vector and the center of the rotor N pole is substantially zero. That is,
The current vector will be at the center of the monotonically increasing phase difference region.

FIG. 8 shows another example of the embodiment of the new command converter 9, which is different from the embodiment of FIG. In the figure, the speed controller 10 is also shown in order to clarify the relationship between the new command generator 9 and the speed controller 10. D-axis current command generator 9a in new command generator 9
Is similar to the embodiment of FIG. 5, and may be designed and realized as described with reference to FIG. A major difference between the embodiment of FIGS. 8 and 5 is that the q-axis current command generator 9b has a more elaborate configuration. The q-axis current command generator main part 9ba is the same as 9b in the embodiment of FIG. 5, and generates the q-axis current command value in a proportional relationship according to the torque command value. On the other hand, the command switching control unit 9bb
Receives a speed command value and a speed deviation as inputs, and controls selection switching of a q-axis current command value. That is, q
The selection of the output of 9 ba or the zero signal is controlled as the shaft current command value.

FIG. 9 is a flowchart showing the contents and method of processing by the command switching control section 9bb in order to contribute to the realization of the q-axis current command generator 9b by software. That is, first, it is determined whether or not the speed command value is zero in s11, and if true, the process proceeds to s12. On the contrary, if false, s14
The switch of the q-axis current command value is switched so as to select the output of the q-axis current command generator main unit 9ba. s1
In the case of proceeding to 2, it is determined whether or not the absolute value of the estimated speed is smaller than a small positive allowable value De.
Proceeding to 3, the switch of the q-axis current command value is switched to the zero selection side. If false, the process proceeds to s14, and the switch of the q-axis current command value is switched to select the output of the q-axis current command generator main unit 9ba.

As is clear from the description using the flowchart of FIG. 9, if the new current command generator shown in FIG. 8 is used,
In a state where the speed is substantially zero, the spatial phase difference of the current vector with respect to the center of the rotor N pole is independent of the control method employed by the speed controller, such as P (proportional) control or PI (proportional integral) control. The armature current can be controlled to be substantially zero (rad). That is, if the new current command generator shown in FIG. 8 is used, in the state of substantially zero speed, regardless of the control method adopted in the speed controller, the current vector is in the phase difference region of the monotonically increasing characteristic. Can be controlled to exist at the center.

Although the present invention has been described above using the example of speed control for controlling the rotor speed of a synchronous motor, it is obvious to those skilled in the art that the present invention is not limited to speed control. It is pointed out that it can also be used for torque control. For example, in the case of torque control, the torque command value that is an input to the new command converter 9 may be directly given to the torque command value instead of the output signal of the speed controller in speed control. FIG. 10 shows an example of the torque control corresponding to FIG. The operation of the new command converter 9 in FIG. 10 is the same as in the case of FIG. Also in the example of FIG. 10, when the torque command value is zero, the spatial phase difference of the current vector with respect to the center of the rotor N pole is substantially zero (rad).
The armature current is controlled so that That is, by setting the torque command value to zero, it is possible to control the current vector to be present at the center of the phase difference region that is monotonically increasing.

The magnetic flux position / velocity estimator 4 in the embodiment of FIG. 4 uses current and voltage information on the dq coordinate system similar to that of FIG. 11, but it is easily understood by those skilled in the art by the above description. As can be appreciated, the present invention can be used regardless of the internal configuration of the magnetic pole position / velocity estimator. For example,
The present invention can be used for a magnetic pole position / velocity estimator for estimating a magnetic flux position or speed using current and voltage information on a fixed coordinate system, or a vector control system using a magnetic pole position detector which may involve a detection error.

[0044]

As is clear from the above description, the present invention has the following effects. In particular, according to the first aspect of the present invention, the current vector is in a phase difference region where the relationship between the spatial phase difference of the current vector with respect to the center direction of the rotor permanent magnet N pole and the rotor generated torque is monotonically increasing. Therefore, even if the spatial phase difference is suddenly increased by external force and the increase in the spatial phase difference cannot be accurately grasped, the generated torque of the motor can be controlled by the external phase force. The monotonically increasing characteristic increases instantaneously with the increase, and the effect of being able to withstand an unexpected increase in external force is obtained. As a result, the drive control system aimed at by the present invention is easily destabilized. No, in other words, an effect is obtained that a new function for enhancing the stability can be added to the drive control system.

In particular, according to the second aspect of the present invention, the d-axis of the dq coordinate system is selected in the direction of the center of the north pole of the rotor permanent magnet of the permanent magnet synchronous motor or its estimated direction.
Since the d-axis current command value for controlling the d-axis component of the current vector in the current control step is a positive level, the absolute value of the spatial phase difference of the current vector with respect to the center of the rotor permanent magnet N pole is π / 2 ( (rad) can be easily performed. As a result, the effect that the drive control system is not easily destabilized, that is, the purpose of the present invention, that is, the drive control system is provided with a new function for increasing the stability, can be easily achieved.

In particular, according to the third aspect of the present invention, in the current control step on the dq coordinate system, the armature is so arranged that the current vector is present at the center of the phase difference region which is monotonically increasing in the state of zero speed. Since the current is controlled, it is possible to obtain an effect that the highest instantaneous drag can be applied to an unexpected instantaneous increase of the external force when the speed is zero. As a result of this action, even in the region of zero speed where the S / N ratio of the voltage signal is minimized,
The effect that the present invention does not easily destabilize, that is, the function of stability can be maintained is obtained.

[Brief description of the drawings]

FIG. 1 shows an example of a spatial phase difference relationship between a magnetic flux vector and a current vector defined in a certain dq coordinate system with respect to the center of a rotor permanent magnet N pole.

FIG. 2 shows an example of a generated torque characteristic that is monotonically increasing and monotonically decreasing with respect to a spatial phase difference.

FIG. 3 is an example of a spatial phase difference relationship between a magnetic flux vector and a current vector when a d-axis current takes a positive level value in a dq coordinate system synchronized with the center of a rotor permanent magnet N pole.

FIG. 4 is a block diagram showing a basic configuration of a vector control device according to the embodiment;

FIG. 5 is a block diagram showing a schematic configuration of a new command converter according to the embodiment;

FIG. 6 shows an example of an output characteristic of the d-axis current command generator according to the embodiment;

FIG. 7 is a signal processing flowchart for realizing output characteristics of a d-axis current command generator according to the embodiment;

FIG. 8 is a block diagram showing a schematic configuration of a new command converter according to the embodiment;

FIG. 9 is a signal flow chart showing an operation of a command switching control unit according to the embodiment;

FIG. 10 is a block diagram showing a schematic configuration of a new command converter according to the embodiment;

FIG. 11 is a block diagram showing a schematic configuration of a conventional vector control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Permanent magnet synchronous motor 2 Current detector 3 Power converter 4 Magnetic pole position velocity estimator 5a Three-phase two-phase converter 5b Two-phase three-phase converter 6a Vector rotator 6b Vector rotator 7 Current controller 8 (conventional) Command converter 9 New command converter (of the present invention) 9a d-axis current command generator 9b q-axis current command generator 9ba q-axis current command generator main part 9bb command switching control unit 10 speed controller

Claims (3)

    [Claims]
  1. A d-axis and a q-axis which are orthogonal to each other;
    A vector control method for a permanent magnet synchronous motor having a current control step of dividing and controlling all or a part of an armature current as a d-axis component and a q-axis component of a current vector on a q coordinate system. In the step, in at least a part of the speed region, the current vector is set within a phase difference region in which the relation between the spatial phase difference of the current vector with respect to the center direction of the rotor permanent magnet N pole and the rotor generated torque is monotonically increasing. A vector control method for a permanent magnet synchronous motor, wherein an armature current is controlled so that the armature current exists.
  2. 2. The d-axis of the dq coordinate system is selected in the direction of the center of the north pole of the rotor permanent magnet of the permanent magnet synchronous motor or in the direction of estimation thereof, and the d-axis component control of the current vector in the current control step is performed. Current command value is set to a positive level to control the armature current so that the absolute value of the spatial phase difference of the current vector with respect to the center of the N pole is less than π / 2 (rad). The vector control method for a permanent magnet synchronous motor according to claim 1, wherein:
  3. 3. In the current control step on the dq coordinate system, in a state of zero speed, the armature current is controlled so that the current vector is present at the center of a monotonically increasing phase difference region. 2. The vector control method for a permanent magnet synchronous motor according to claim 1, wherein:
JP2000031205A 2000-01-02 2000-01-02 Vector control method for permanent magnet synchronous motor Expired - Lifetime JP3735836B2 (en)

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JP2003037988A (en) * 2001-07-26 2003-02-07 Sanyo Electric Air Conditioning Co Ltd Method and device for driving brushless dc motor
US6639377B2 (en) * 2001-03-08 2003-10-28 Hitachi, Ltd. Driving device for synchronous motor
US6906491B2 (en) * 2003-06-20 2005-06-14 Rockwell Automation Technologies, Inc. Motor control equipment
US7679308B2 (en) 2006-06-28 2010-03-16 Sanyo Electric Co., Ltd. Motor control device
CN102668361A (en) * 2009-12-24 2012-09-12 株式会社安川电机 Motor control apparatus and magnetic-pole position detection method therefor
DE112010005230T5 (en) 2010-02-04 2012-11-22 Mitsubishi Electric Corporation Elevator control
CN104242773A (en) * 2013-06-20 2014-12-24 通力股份公司 Method and apparatus for controlling an electric motor of an elevator

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CN104639000A (en) * 2014-12-12 2015-05-20 西北工业大学 Permanent magnet synchronous motor vector control speed regulating method based on MEMS (micro electro mechanical system) gyro

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6639377B2 (en) * 2001-03-08 2003-10-28 Hitachi, Ltd. Driving device for synchronous motor
JP2003037988A (en) * 2001-07-26 2003-02-07 Sanyo Electric Air Conditioning Co Ltd Method and device for driving brushless dc motor
US6906491B2 (en) * 2003-06-20 2005-06-14 Rockwell Automation Technologies, Inc. Motor control equipment
US7679308B2 (en) 2006-06-28 2010-03-16 Sanyo Electric Co., Ltd. Motor control device
CN102668361A (en) * 2009-12-24 2012-09-12 株式会社安川电机 Motor control apparatus and magnetic-pole position detection method therefor
DE112010005230T5 (en) 2010-02-04 2012-11-22 Mitsubishi Electric Corporation Elevator control
CN104242773A (en) * 2013-06-20 2014-12-24 通力股份公司 Method and apparatus for controlling an electric motor of an elevator
EP2819296A3 (en) * 2013-06-20 2015-06-10 Kone Corporation Method and apparatus for controlling an electric motor of an elevator
US9731935B2 (en) 2013-06-20 2017-08-15 Kone Corporation Method and apparatus for controlling an electric motor of an elevator without an encoder

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