JP3209854B2 - Control device for synchronous reluctance motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC servo motor,
The present invention relates to a control device for a synchronous motor known as a synchronous reluctance motor.

[0002]

2. Description of the Related Art As a conventional control system of an improved synchronous reluctor <br/> Nsumota, the rotor position as shown in FIG. 10, performs detection of rotor speed is controller for precise speed control.

A conventional example shown in FIG. 10 will be described.

[0004] The synchronous reluctance motor has a salient pole type rotor 6, to which a position detector 5 is mechanically coupled, and outputs a position signal DS.

The rotor rotation position AR is the position of the magnetic pole of the rotor 6 with respect to the U-phase winding position as shown in FIG.

The speed command SI and the speed signal SD detected by the speed detecting means 3 are compared by the adder 1 to obtain a speed deviation ES, and the speed control means 2 performs a compensation operation such as proportional, integral and differential. Obtain a torque command T.

The torque direction discriminating means 13 receives the torque command T as an input, discriminates whether the polarity is positive or negative, and outputs a discrimination signal DIR
Is sent to the relative phase angle selecting means 14 to output +45 degrees or -45 degrees as the relative phase angle A between the magnetic pole position of the rotor 6 and the current phase for generating the rotating magnetic field of the three-phase AC motor due to the positive and negative polarities.

The adder 15 adds and synthesizes the relative phase angle A and the rotor position AR obtained by the rotor position detecting means 4 to obtain the phase (AR + A) of the three-phase AC motor current.

A current command means 10 receives a torque command T and a phase AC of a motor current as inputs, and outputs a three-phase current command SIU,
Create SIV and SIW.

When the torque command T is positive, the following is performed.

[0011] SIU = | T | · SIN ( AR + 45 °) SIV = | T | · SIN (AR + 45 ° - 120 °) SIW = | T | · SIN (AR + 45 ° - 240 °) i.e., relative in the conventional phase angle A Is the magnetomotive force component T
45 ° is selected so that SIN (A) and armature current component T · COS (A) are equal. Similarly, the command T
When is negative:

[0012] SIU = | T | · SIN ( AR-45 °) SIV = | T | · SIN (AR-45 ° - 120 °) SIW = | T | · SIN (AR-45 ° - 240 °) current control The circuit 7 receives and amplifies the current commands SIU, SIV, SIW and supplies the three-phase currents IU, IV, IW to the windings U, V, W of the three-phase motor.

As a result of such control, a motor current having a phase difference of +45 degrees or −45 degrees always flows with respect to the direction of the magnetic pole of the rotor. The torque of rotation can be generated arbitrarily,
Speed control of the electric motor is performed.

[0014]

In the conventional example shown in FIG.
As shown, the magnetomotive force component of the field is T · SIN45.
゜, the armature current component is T · COS45 ゜ and their ratio is fixed.

[0015] The problem of this prior art is that the motor back-induced voltage becomes too large above the base rotation speed of the motor, and it becomes difficult to operate above the rotation speed at which the motor back-induced voltage becomes larger than the power supply voltage of the current control circuit. It is. In other words, the output torque at or above the base rotation speed is limited to a small value.

Another problem is that when the motor output takes a value near the rated value or a value larger than the rated value, an excessive magnetomotive current flows through the field, and the motor power factor decreases.
Since the power element of the current control circuit is relatively large, there is a problem that the cost of the entire device increases.

Another problem is that the relationship between the motor current and the generated torque of the synchronous reluctance motor utilizing the reluctance force is non-linear. Therefore, in the prior art shown in FIG. Conversely, there is a problem that the control sensitivity becomes too high where the output torque is large, and the speed control tends to be oscillating.

[0018]

According to the present invention, in order to solve the above problems, the relative phase angle between the position of the magnetic pole of the rotor and the motor current that generates the rotating magnetic field is determined by the appropriate magnetic flux in the motor. In other words, a relative phase angle creating means for creating a relative phase angle so that the exciting current component and the armature current component of the motor current are appropriate, and compensating for the non-linearity between the motor current amplitude and the generated torque. Current amplitude creating means for creating an appropriate motor current amplitude.

[0019]

The relative phase creating means reduces the relative phase angle between the rotor and the motor current at a speed higher than the base rotation speed of the motor to enable high-speed rotation, and further reduces the relative phase angle even when the motor current increases. To appropriately control the magnetic flux in the motor. When the viewpoint is changed, a useless exciting current component is prevented from flowing, so that the power factor of the motor can be improved.

Further, the current amplitude creating means adds nonlinear compensation to the magnitude of the motor current with respect to the torque command of the motor, thereby obtaining the speed control stability of the synchronous reluctance motor .

[0021]

FIG. 1 shows an embodiment of the present invention. The description of the same components as in FIG. 10 showing the conventional example is omitted.

First, the general operation will be described. The relationship among the current amplitude command IOS, the rotor position AR, the relative phase angle A, and the three-phase current commands SIU, SIV, SIW is as follows: SIU = IOS.SIN (AR + A ) SIV = IOS.SIN (AR + A − 120 °) SIW = IOS · SIN (AR + A − 240 °) The current control circuit 7 amplifies the current command SIU, SIV, SIW as an input, and applies the current command to each winding U, V, W of the three-phase motor. Provides phase currents IU, IV, IW.

The magnetomotive force component applied to the field magnetic circuit including the rotor is IOS · SIN (A), and the current component flowing through the motor winding facing the magnetic pole of the rotor, that is, the armature current component is IOS · COS (A). Becomes

The torque generated by the motor is determined by the magnetomotive force component IO.
S · SIN (A) and the armature current component IOS · COS
It is proportional to the vector product with (A).

This indicates that if the motor current amplitude IOS and the relative phase angle A can be arbitrarily controlled, any motor torque control is possible, and precise speed control and position control are possible.

But what kind of synchronous slira
The above-described control does not always enable efficient operation of the conductance motor .

The present invention provides a synchronous reluctance motor capable of stably generating a field magnetic flux by a magnetic pole of a rotor and allowing a current interlinking with the field magnetic flux to flow, for more efficient operation. realizable.

Synchronous Reactor Especially Appropriate for the Present Invention
An example of a drive motor is shown.

FIG. 7 is an example of a sectional view of a rotor of a synchronous reluctance motor . Reference numeral 30 denotes a shaft of the rotor, 31 denotes an electromagnetic steel plate which is laminated, and 32 denotes a magnetic insulating portion formed by stamping out the electromagnetic steel plate.

Each magnetic path is connected between the outer peripheral portion of the rotor and the intermediate portion of each magnetic pole. The main purpose is to facilitate the handling and assembling of the electromagnetic steel sheet 31 and to firmly fix the electromagnetic steel sheet 31 to the shaft 30 as a rotor. It is electromagnetically inevitable.

In the rotor having such a structure, the magnetic reluctance of the adjacent magnetic poles is small, the field magnetic flux can be easily excited, and the magnetic reluctance viewed from both ends of the magnetic poles in the rotation direction is large, so that the rotor faces each magnetic pole. The structure is such that the disturbance of the field magnetic flux of each magnetic pole due to the current flowing through the stator is small. As a result, the synchronous reluctance motor can be operated more efficiently.

When the outer peripheral portion of the rotor is connected, there is an effect of reducing the torque ripple caused by the slot and an effect of reducing the magnetic resistance of the field.

FIG. 8 is another example of a sectional view of a rotor of a synchronous reluctance motor . 30 is the axis of the rotor, 33
Is an electromagnetic steel plate, which is laminated, and 34 is a magnetic insulating portion formed by stamping out the electromagnetic steel plate.

Each magnetic path is connected between the outer peripheral portion of the rotor and the intermediate portion of each magnetic pole. This has the same purpose and effect as the example of FIG.

The example of FIG. 8 is different from FIG. 7 in that the magnetic poles are more effectively used between the magnetic poles and that the change in the rotation direction of the rotor magnetic resistance is relatively smooth.

Next, a method of controlling the motor current amplitude value IOS and the relative phase angle A will be described in more detail.

The relative phase angle creating means 9 is a synchronous
The magnetic flux of the lactance motor can be controlled to an appropriate value. Specifically, the exciting current component IF of the motor is set to a fixed value or less at a base rotation speed NB or lower, and the motor reverse induced voltage is set at a base rotation speed NB or higher. Is reduced so that is substantially constant, that is, 1 / along with the rotation speed SD.
The relative phase angle A is generated so as to decrease the exciting current component IF in proportion to SD.

FIG. 2 shows an example of specific characteristics of the relative phase angle creating means 9, and FIG. 6 is a flowchart of an example of a specific algorithm.

The algorithm of the relative phase angle creating means 9 will be described with reference to FIG.

When the torque command T is 0 ≦ T <T1, the relative phase angle A is a predetermined constant value A0, and when −T1 <T <0, the relative phase angle A is −A0.

Here, the value of T1 is a value at which the motor terminal voltage when the motor current corresponding to the torque command T1 flows at the maximum rotation speed becomes the maximum controllable voltage.

When the torque command T satisfies T1 ≦ T <T3, the value of the relative phase angle A changes from a predetermined constant value A0 to the torque and the rotation.
A = A0−A after reducing the first reduction value AX depending on the number of turns
X , and the second reduction value ADT (T) depending on the torque
Is ADT (T) = 0, and when −T3 <T ≦ −T1, the value of the relative phase angle A is A = −A0 + AX, ADT (T)
= 0.

Where AX is AX = ADC (N) · (|
T | -T1) / (T3-T1).

The ADC (N) is used to obtain a field weakening effect of suppressing the terminal voltage of the electric motor to be equal to or less than the controllable maximum voltage at a high-speed rotation speed higher than the base rotation speed. For example, as shown in FIG. Function.

When the motor control is controlled by a microprocessor, the function can be realized by storing a similar function by a mathematical expression and calculating it each time, or by storing a function pattern on a memory and corresponding to the rotation speed N each time. There is a method of reading out the value of ADC (N).

When the torque command T satisfies T3 ≦ T <T6, the value of the relative phase angle A is reduced from a predetermined constant value A0 to a first reduction value.
A = A where both AX and the second reduction value ADT (T) are reduced.
A0−AX−ADT (T), and −T6 <T ≦ −T3
In the case of, the value of the relative phase angle A is A = −A0 + AX + ADT
(T).

AX = ADC (N), and ADT (T)
Has characteristics shown in FIG. 5, for example. Here, the value of T3 is the value of the torque command T such that the exciting current component of the motor current flowing when T = T3 becomes a value that can induce an appropriate magnetic flux at low speed rotation of the motor , in other words, the exciting value .
The current component is a limit torque value that causes magnetic saturation .
This function ADT (T) can be stored and reproduced in the same manner as ADC (N).

The absolute value | T | of the torque command is | T |
> T3, the absolute value of the relative phase angle according to the value of | T |
The operation of gradually reducing A | means that unnecessary exciting current components of the motor current do not flow. As an effect, the motor current can be reduced, so that the required control device capacity is reduced, and the motor copper loss heat is generated. Can be reduced. At this time, preventing unnecessary excitation current from flowing also improves the power factor of the motor.

The current amplitude command means 8 receives the torque command T and outputs a current amplitude command IOS. The current amplitude command IOS is a simple amplification, or the current amplitude command IOS is a square root of the torque command T as shown in FIG. , | T | = is required so as to be in the relationship of IOS ^2.

The characteristic shown in FIG. 3 is that T = IOS ² when the exciting current component of the motor current is less than a value enough to excite the magnetic flux of the motor, and the torque command T and the current amplitude The command IOS has a linear relationship.

This is to improve the speed controllability of the motor control device by compensating for the non-linearity, since the generated torque of the motor is proportional to the square of the motor current in a range where the exciting current component is a small value. is there.

The current control circuit 7 has, for example, a configuration as shown in FIG. 9, and includes an inverter 54 composed of a power transistor and current detectors 55, 56, 57 for detecting the currents IU, IV, IW of each phase of the motor. Current command value SIU of each phase,
A current control circuit 5 that feeds back the current detection value of each phase to SIV and SIW, and supplies a drive signal to each power transistor of the inverter 54 from each difference signal.
1, 52, and 53.

In the embodiment of the present invention, an example of a method in which the control of the voltage and the current of the motor is directly handled by the three-phase alternating current amount has been described. Are equivalent and are included in the present invention.

The present invention can be applied to a polyphase alternating current other than a three-phase alternating current by modifying the present invention.

The speed controller, the position detector, and the like can be variously modified and are included in the present invention.

[0056]

According to the present invention, it is possible to reduce the relative phase angle between the rotor and the motor current at a speed higher than the base rotation speed of the motor, thereby enabling high-speed rotation.

Further, when the motor current takes a value near or above the rated value, the relative phase angle is reduced so that no useless exciting current component is caused to flow, thereby improving the power factor, and Since the current can be reduced, the power element capacity of the current control circuit can be reduced, the required control device capacity can be reduced, and the cost can be reduced.

At the same time, the motor copper loss heat generation can be reduced, and the continuous rated torque and output of the motor can be increased.

Furthermore, the speed control stability of the synchronous reluctance motor can be enhanced by adding nonlinear compensation to the magnitude of the motor current with respect to the motor torque command by the current amplitude creating means.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a control device for a synchronous reluctance motor according to the present invention.

FIG. 2 is a diagram illustrating a motor rotation speed N and a relative phase angle A according to an embodiment;
FIG.

FIG. 3 shows a torque command T and a current amplitude command I in the embodiment.
It is a characteristic view with OS.

FIG. 4 shows an absolute value | N |
It is a characteristic diagram with DC (N).

FIG. 5 is a characteristic diagram of an absolute value | T | of a torque command and a coefficient ADT (T) in the embodiment.

FIG. 6 is a flowchart illustrating an algorithm for obtaining a relative phase angle A in the embodiment.

FIG. 7 shows a synchronous reluctance smoke suitable for the present invention.
A rotor cross-sectional view of the data.

FIG. 8 shows another synchronous reluctance suitable for the present invention.
It is a rotor sectional view of a motor .

FIG. 9 is a diagram showing a specific example of a current control circuit 7;

FIG. 10 is a diagram showing an example of the related art.

[Explanation of symbols]

 2 speed control means 3 speed detection means 4 rotor position detection means 6 rotor 7 current control circuit 8 current amplitude command means 9 relative phase angle creation means 10 current command means

Claims (2)

(57) [Claims] 1. A control device for a synchronous reluctance motor that obtains a rotational force by utilizing a fact that a magnetic resistance varies depending on a rotational position of a rotor of an electric motor, wherein a position detecting means for detecting a rotational position and a speed of the rotor; Speed control means for obtaining a speed deviation from the speed command of the synchronous reluctance motor and the detected speed of the rotor, performing compensation such as proportional, integral, and derivative to the speed deviation to output a torque command; and generating a rotating magnetic field of the stator. Synthetic phase of motor current
Is the angle formed in the rotational direction with respect to the magnetic pole position of the rotor. The positive and negative polarities of the relative phase angle are determined by the positive and negative polarities of the torque command.
1 (the torque command at which the motor terminal voltage becomes the maximum controllable voltage when the motor current corresponding to the torque command T1 flows at the maximum rotational speed of the motor) (| T |
<T1) or when the rotation speed N is less than or equal to the base rotation speed NB of the electric motor (| N | <NB), the predetermined constant value A0, when the torque command is larger than T1 and the rotation speed is larger than the base rotation speed (| T |> T1, | N |> NB) is that the relative phase angle is large when the torque command T is in the range of T1 <| T | <T3 (T3 is a limit torque value at which the exciting current component causes magnetic saturation). Is set to a value obtained by subtracting the first reduction value AX depending on the torque and the rotation speed from a predetermined constant value A0. When the torque command T is in the range of | T |> T3, the magnitude of the relative phase angle is set to a predetermined value. A relative phase angle creating means for creating a value obtained by subtracting both the first reduction value AX and the second reduction value ADT (T) depending on the torque from the constant value A0, and adding the rotational position of the rotor and the relative phase angle Motor current level that determines the phase of the motor current Phase creating means; current command means for creating a current command value for each phase of the motor from the current amplitude command value of the motor and the phase of the motor current; current control for supplying current to the motor according to the current command value for each phase of the motor A control device for a synchronous reluctance motor, comprising: a circuit; 2. An absolute value of a torque command T and a current amplitude command I.
2. The control device for a synchronous reluctance motor according to claim 1, further comprising a current amplitude command means having a relationship in which the square of the OS is proportional to the square.