JP5482268B2 - Vector control device for synchronous motor - Google Patents

Description

  The present invention relates to a vector control device for handling magnetic flux and current of a field winding type synchronous motor as vectors and controlling an armature current and field current of the motor by a power converter.

As a conventional vector control device of a field winding type synchronous motor driven by a power converter, those described in Non-Patent Document 1, Patent Document 1, Patent Document 2, and the like are known.
FIG. 6 is a rewrite of the magnetic flux calculation, magnetic flux control, and current control portions related to the present invention, based on the block diagrams and descriptions described in FIGS. 6.5 and 6.6 in Chapter 6 of Non-Patent Document 1. FIG. FIG. 7 is an example of a vector diagram showing the relationship among the magnetic flux, current, and voltage of the synchronous motor in this prior art.

First, the definition and symbols of coordinate axes will be described. That is, the magnetic pole direction of the field winding type synchronous motor is defined as a d-axis (magnetic pole axis), and the direction electrically orthogonal to the d-axis is defined as a q-axis. The direction of the armature wire linkage magnetic flux vector interlinking with the armature winding is defined as the M axis, and the direction electrically orthogonal to the M axis is defined as the T axis.
For example, the d-axis and q-axis components of the armature current are d-axis current I _d and q-axis current I _q, and an armature current vector obtained by synthesizing these currents is expressed as I _a →.

In the block diagram of FIG. 6, the armature linkage magnetic flux interlinking with the armature winding is calculated as _a vector, and the armature current component parallel to this armature linkage flux vector Φ _a → (hereinafter referred to as magnetizing current). The power factor of the synchronous motor is controlled to 1 by controlling the steady value of I _M to zero. In the vector diagram of FIG. 7, when the magnetizing current I _M is zero, in other words, if the armature current vector I _a → exists on the T-axis as illustrated, the armature voltage vector V _a → It is shown that the direction of the child current vector I _a → coincides and the power factor of the synchronous motor becomes 1. These points are the same in Patent Document 1 and Patent Document 2, and control based on the above principle is performed.
Next, the contents of FIGS. 6 and 7 will be described in detail.

First, the configuration and function of the magnetic flux calculator 1 surrounded by a broken line in FIG. 6 will be described.
The coordinate converter 10, the magnetization current target value I _M ^*, current component acting on the torque generated in perpendicular to the magnetization current target value I _M ^* (hereinafter, referred to as torque current) target value I _T ^* is input The coordinate converter 10 rotates the coordinates of the target values I _M ^* and I _T ^* by an angle δ _a (see FIG. 7) input from the vector calculator 18 (to be described later) according to Equation 1, and d The target values I _d ^* and I _q ^* of the shaft current and q-axis current are output.

The d-axis current target value I _d ^* and the field current target value I _f ^* are added by the adder / subtractor 11 to become an input signal of the function unit 12, while the q-axis current target value I _q ^* is directly used by the function unit 13. Input signal. Functions set in the function units 12 and 13 are the functions shown in Formulas 2 and 3 based on the equivalent circuit of the synchronous motor and its definition. The outputs of the function units 12 and 13 are respectively the stator core and the rotation. The d and q axis components Φ _gd and Φ _gq of the gap magnetic flux between the core and the core are obtained.
In Equations 2 and 3, L _ad and L _aq are the d-axis and q-axis components of the armature leakage inductance, L _Dd and L _Dq are the d-axis and q-axis components of the braking winding leakage inductance, and R _Dd and R _Dq is a d-axis and q-axis component of the braking winding resistance, and s is a Laplace operator.

The d-axis current target value I _d ^* and the field current target value I _f ^* are input to amplifiers 14 and 15 having a gain L ₁ corresponding to the armature leakage inductance. In the adder / subtracters 16 and 17, the air gap magnetic fluxes Φ _gd and Φ _gq are added, respectively. Thereby, the magnetic flux due to the armature leakage inductance is added to the gap magnetic fluxes Φ _gd and Φ _gq , and the armature interlinkage magnetic fluxes Φ _ad and Φ _aq are calculated, respectively. These armature linkage magnetic fluxes Φ _ad and Φ _aq are input to the vector calculator 18, and the magnitude Φ _a of the armature linkage magnetic flux is calculated by Equation 4 and the angle δ _a is calculated by Equation 5.

The magnetic flux adjuster 20 amplifies the deviation between the target value Φ _a ^{* of} the armature flux linkage obtained by the adder / subtractor 19 and the calculated value Φ _a to calculate the magnetizing current target value I _μ ^* . Meanwhile, the angle [delta] _a and is input to a cosine function unit 21 obtains the function cos [delta] _a is input to a divider 22, dividing the magnetization current target value I _mu ^* at cos [delta] _a in the divider 22 Thus, the field current target value I _f ^* is calculated. This field current target value I _f ^* is input to the adder / subtractor 11 and an adder / subtractor 23 described later.

Magnetization current target value I _M ^* calculation means is is not shown, the control system so that I _M ^* becomes zero during steady field current I _f coincides with the target value I _f ^* is configured ing.
On the other hand, the rotor position θ as the previous angle [delta] _a are added by the adder-subtracter 25 the angle phi (see FIG. 7) is calculated. Also, I _alpha obtained by converting 3-phase / 2-phase three-phase armature current, the I _beta, the coordinate converter 26, it is converted into a magnetizing current I _M and the torque current I _T based on the angle phi.

Deviation between the magnetization current target value I _M ^* and the magnetization current I _M, and, the deviation between the torque current target value I _T ^* and the torque current I _T is calculated respectively by the subtractor 27, current regulating these deviations By amplifying by the unit 29, the M-axis voltage target value V _M ^* and the T-axis voltage target value V _T ^* are calculated.
These voltage target values V _M ^* and V _T ^* are converted into voltage target values V _α ^* and V _β ^* on the α and β axes by the coordinate converter 30, and further via the two-phase / three-phase converter 31. Are converted into three-phase voltage command values V _u ^{* to} V _w ^* . According to these voltage command values V _u ^{* to} V _w ^* , the output voltage of a power converter such as a cycloconverter (not shown) is controlled, and feedback control is executed so that a target armature current is obtained.
A deviation between the field current target value I _f ^* and the field current _If is calculated by the adder / subtractor 23, and the field voltage command value V _f ^* is calculated by amplifying the deviation by the current regulator 24. The

JP-A-4-101169 (paragraphs [0003], [0004], FIG. 3, FIG. 4 etc.) JP-A-9-182499 (page 2, upper left column, line 4 to page 3, upper left column, line 9, FIG. 6, FIG. 7 etc.)

Takayoshi Nakano, “Vector Control of AC Motor”, p. 111-p. 126, Chapter 6 Vector Control System for Synchronous Motor, Nikkan Kogyo Shimbun, March 1996

In the prior art described above, the output of the synchronous motor is to be increased within the voltage / current range that can be output by the power converter or within the allowable input voltage / current range of the synchronous motor. The power factor at the armature winding terminal of the motor is controlled to be 1.
However, in such a method, the maximum torque that should originally be obtained may not be obtained depending on the operating conditions. The reason will be described below.

In other words, since the magnetic saturation phenomenon of the motor has a characteristic depending on the size of the air gap magnetic flux, the air gap magnetic flux is controlled to the limit that the magnetic saturation can be tolerated, and the armature current component parallel to the air gap magnetic flux vector is controlled to zero. In other words, controlling the power factor to 1 with respect to the induced voltage caused by the air gap magnetic flux is a condition for obtaining the maximum torque under a predetermined armature current, whereas the conventional technique has such a problem. Is not solved.
When the power factor with respect to the induced voltage is controlled to 1, the armature voltage increases as compared with the conventional method in which the power factor at the armature winding terminal is controlled to 1, but for example, it is necessary for low-speed rotation of a synchronous motor in the first place. Since the armature voltage is lowered, it is not a problem that the armature voltage rises at a low speed.
SUMMARY OF THE INVENTION An object of the present invention is to provide a vector control device for a synchronous motor that can obtain a maximum output or a maximum torque within a predetermined armature current range regardless of the rotational speed.

In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a synchronous motor vector control device which treats magnetic flux and current of a field winding type synchronous motor as a vector and controls an armature current and a field current by a power converter. In
When the rotational speed of the motor is lower than a predetermined value, the steady value of the armature current component parallel to the air gap magnetic flux vector is controlled to zero,
When the rotational speed of the motor is higher than a predetermined value, the steady value of the armature current component parallel to the armature flux linkage vector is controlled to zero.

The invention according to claim 2 is the vector controller for the synchronous motor according to claim 1,
When the rotational speed of the motor is lower than a predetermined value, the gap magnetic flux is controlled so that the size of the gap magnetic flux vector matches the first target value, and when the rotational speed of the motor is higher than the predetermined value, The armature linkage magnetic flux is controlled such that the magnitude of the armature linkage magnetic flux vector coincides with a second target value smaller than the first target value.

The invention according to claim 3 is the vector control device for the synchronous motor according to claim 2,
When the rotational speed transitions from low speed to high speed or from high speed to low speed,
Continuously changing the target value of the magnitude of the magnetic flux vector from the first target value to the second target value or from the second target value to the first target value; and From the calculated value of the gap magnetic flux vector to the calculated value of the armature linkage magnetic flux vector, or from the calculated value of the armature linkage magnetic flux vector Is continuously changed to a calculated value of.

  According to a fourth aspect of the present invention, in the synchronous motor vector control device according to the first aspect, the armature voltage of the motor is used instead of the rotational speed. In this case, according to the magnitude of the armature voltage proportional to the rotation speed, the gap magnetic flux is controlled so that the magnitude of the gap magnetic flux vector coincides with the first target value, or the armature linkage flux The armature flux linkage may be controlled so that the magnitude of the vector matches the second target value.

According to the present invention, at the time of high speed rotation of the synchronous motor, the power factor at the armature winding terminal is controlled to 1, thereby obtaining the maximum output within the limit of the voltage / current allowable by the power converter or the synchronous motor. be able to. Further, by controlling the power factor with respect to the induced voltage of the synchronous motor to 1 at the time of low-speed rotation where the armature voltage decreases, the maximum torque can be obtained within the limit of the current that can be permitted by the power converter or the synchronous motor. .
As a result, regardless of the rotational speed of the synchronous motor, the maximum output or the maximum torque can always be obtained within the allowable limit of voltage and current.
In particular, according to the invention according to claim 2, since the gap magnetic flux of the synchronous motor can be controlled to a limit that allows magnetic saturation, the maximum torque that can be output at the time of low-speed rotation increases, and according to the invention according to claim 3. For example, there is an effect that torque disturbance is not generated by smoothly switching the magnetic flux calculation value.

Furthermore, the present invention has the following advantages.
Generally, as the output frequency of the power converter decreases, the thermal duty of the power semiconductor device becomes more severe, and the maximum current that can be output by the power converter decreases. As for the synchronous motor, the allowable value of the armature current decreases as the rotational speed decreases. According to the present invention, since the influence of this problem can be reduced, a sufficient armature current can be passed even at a low speed, and a reduction in torque can be prevented.

It is a block diagram which shows the principal part of 1st Embodiment of this invention. It is a vector diagram which shows the relationship of the magnetic flux of the synchronous motor in 1st Embodiment of this invention, an electric current, and a voltage. It is a block diagram which shows the principal part of 2nd Embodiment of this invention. It is a block diagram which shows the principal part of 3rd Embodiment of this invention. It is a block diagram which shows the principal part of 4th Embodiment of this invention. It is a block diagram based on the prior art described in the nonpatent literature 1. It is a vector diagram which shows the relationship of the magnetic flux of the synchronous motor in FIG. 6, an electric current, and a voltage.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 is a block diagram showing the configuration of a magnetic flux calculator 1A in the first embodiment of the present invention, and FIG. 2 is a vector showing the relationship between magnetic flux, current and voltage of a synchronous motor for explaining the principle of this embodiment. FIG. In these drawings, the same reference numerals as those in FIGS. 6 and 7 indicate the same functions and the same signals.

A magnetic flux calculator 1A in FIG. 1 is obtained by adding a coordinate rotator 32, an absolute value calculator 33, and first and second switchers 34 and 35 to the magnetic flux calculator 1 shown in FIG. The description will focus on the parts different from FIG.
The coordinate rotator 32 calculates the magnitude Φ _g and the angle δ _g of the gap magnetic flux vector from the gap magnetic fluxes Φ _gd and Φ _gq output from the function units 12 and 13.

The first switch 34 receives the armature linkage flux vector magnitude Φ _a and the gap flux vector magnitude Φ _g , and the second switch 35 receives the armature linkage flux vector angle. angle [delta] _g of [delta] _a and the air-gap flux vector is input. Further, ω _r is the rotation speed of the synchronous motor, and the speed absolute value ω _rABS calculated by the absolute value calculator 33 is input to the first and second _switches 34 and 35.

The first switch 34 outputs the magnitude Φ _g of the air gap magnetic flux vector as a signal Φ ₀ at a low speed where the rotational speed is less than a predetermined value according to the absolute speed value _ωrABS , and the rotational speed is greater than or equal to the predetermined value. the certain high speeds to switching operation so as to output a magnitude [Phi _a of the armature flux linkage vector as a signal [Phi _0. Here, the signal Φ ₀ is fed back to the input side of the magnetic flux regulator 20 and used for the calculation of the magnetizing current target value I _μ ^* as in FIG.
Similarly, the second switch 35 _{outputs the} air gap magnetic flux vector angle δ _g as a signal δ ₀ at low speeds and the armature linkage magnetic flux vector angle δ _a at high speeds in response to the absolute velocity value ω _rABS. to switch operates so as to output as [delta] _0. The signal δ ₀ is input to the coordinate converter 10 as described below, and is used for the calculation of the field current target value I _f ^* via the cosine function unit 21 and the divider 22 in FIG.

Here, since the signal δ ₀ becomes an input signal for setting the coordinate rotation angle of the coordinate converter 10, I _M0 ^* coordinate-converted by the coordinate converter 10 is the calculation method of the signal δ ₀ , that is, the second Depending on whether the switch 35 selects the angle δ _g or the angle δ _a , it corresponds to the target value of the magnetizing current parallel to the gap magnetic flux vector Φ _g → at the low speed, and the conventional armature linkage at the high speed. This corresponds to the target value of the magnetizing current parallel to the magnetic flux vector Φ _a →.
Accordingly, the steady value of I _M0 ^* (in other words, the steady value of the armature current component parallel to the gap magnetic flux vector Φ _g → at low speed rotation, and parallel to the armature linkage magnetic flux vector Φ _a → at high speed rotation. The steady state value of the armature current component) is controlled to zero so that the armature current component is only the torque current, and at low speed, the induced voltage vector E _a → and the armature current vector I _a → are in phase and the induced voltage The power factor with respect to the armature winding terminal can be set to the same phase at the time of high speed and the armature voltage vector V _a → and the armature current vector I _a → are in phase as in the prior art of FIG. Can be 1.

Note that I _T0 ^* coordinate-transformed by the coordinate converter 10 corresponds to the target value of the torque current orthogonal to the gap magnetic flux vector Φ _g → at low speed, and orthogonal to the armature linkage magnetic flux vector Φ _a → at high speed. This corresponds to the target value of the torque current to be performed.
For other parts, Φ _a , δ _a , I _M ^* , and I _T ^* in the prior art of FIG. 6 are replaced with Φ ₀ , δ ₀ , I _M0 ^* , and I _T0 ^* in FIG. Since the basic configuration and operation of the control system are the same as those of the prior art, description thereof is omitted.

FIG. 2 is a vector diagram of the synchronous motor when the magnetization current parallel to the gap magnetic flux vector Φ _g → is controlled to zero. As shown in the figure, since the direction of the induced voltage vector E _a → and the armature current vector I _a → is the same, the power factor for the induced voltage is 1.

Next, FIG. 3 is a block diagram showing a main part of the second embodiment of the present invention.
The feature of the second embodiment is that the magnetic flux target value is changed to Φ _0H ^* or Φ _0L ^* (Φ by the third switch 36 using the velocity absolute value ω _rABS calculated in the magnetic flux calculator 1A of the first embodiment. _0H ^* > Φ _0L ^* ) to be output. The configuration after the switch 36 is the same as the configuration after the adder / subtractor 19 in FIG.
As a switching principle in the switch 36, the signal Φ ₀ ^* is selected by selecting a large magnetic flux target value Φ _0H ^* at low speed and a small magnetic flux target value Φ _0L ^* at high speed according to the absolute velocity value ω _rABS ^. Output as. In the next stage adder / subtractor 19, the deviation between the signal Φ ₀ ^* and the magnetic flux calculation value Φ ₀ is calculated and controlled to a desired magnetic flux by the magnetic flux regulator 20.

Next, the reason for switching the magnetic flux target value as in the second embodiment will be described with reference to the vector diagram of FIG.
The vector diagram of FIG. 7 shows a state where the power factor at the armature winding terminal is 1, and when the magnetic flux by the gain L ₁ is added to the gap magnetic flux vector Φ _g →, the armature linkage magnetic flux vector Φ _a → is obtained. Since the armature current vector I _a → and the gap magnetic flux vector Φ _a → are orthogonal to each other, it can be seen that the gap magnetic flux vector Φ _a → is larger than the armature linkage magnetic flux vector Φ _a →.
As described above, by a magnetic flux calculator 1A, since the low speed magnitude [Phi _a of the air-gap flux vector is feedback controlled as a flux operation value [Phi _0, by choosing a large flux target value [Phi _0H ^* the switcher 36 The magnetic flux target value Φ ₀ ^* is set higher than the target value of the armature linkage magnetic flux to increase the limit of the maximum torque. Since the configuration and operation of other parts are the same as those in the first embodiment, description thereof is omitted.

Next, a third embodiment of the present invention will be described. This embodiment relates to the first to third switchers 34, 35, and 36 in FIGS. 1 and 3, and these configurations and operations are all the same except for input signals. One switching device 34 will be described with reference to FIG.
In FIG. 4, the function set in the function unit 37 is a non-linear function having a polygonal line characteristic in which the input signal shown on the horizontal axis is the velocity absolute value ω _rABS and the output signal G shown on the vertical axis changes in the range of 0 to 1. is there. Since the adder / subtracter 40 performs an operation of subtracting the signal G from 1, the output signal A changes from 0 at low speed to 1 at high speed.
The first multiplier 38 multiplies the gap magnetic flux vector magnitude Φ _g and the signal G, the second multiplier 39 multiplies the armature flux linkage vector magnitude Φ _a and the signal A, and the output of these multipliers 38, 39 is the magnetic flux operation value [Phi ₀ are added by the adder-subtracter 41.

With the above configuration, the magnetic flux calculation value Φ ₀ becomes Φ _g at a very low speed when the signal G = 1, becomes Φ _a at a very high speed when the signal G = 0, and the signal G is between 1 and 0. the fast areas in taking a value, an intermediate value between [Phi _g and [Phi _a. In this embodiment, the magnetic flux calculation value Φ ₀ that smoothly changes in accordance with the velocity absolute value ω _rABS is obtained in this way.
As a result, the magnetic flux calculation value Φ ₀ continues smoothly with changes in the speed of the synchronous motor, and there is no possibility of disturbance of torque control or speed control when switching the magnetic flux calculation.

Next, a fourth embodiment of the present invention will be described. This embodiment, characterized in that in place of the first to third switching flux operation value [Phi ₀ corresponding to the speed absolute value omega _RABS in the embodiment, switching the magnetic flux calculation value [Phi ₀ example by the magnitude of the armature voltage And
FIG. 5 is a block diagram showing the main part of the fourth embodiment. Similar to the third embodiment, the first switch 44 (the first switch in FIGS. 1 and 4 for obtaining the magnetic flux calculation value Φ ₀₎ is shown. The second and third switchers (the second switcher 35 in FIG. 1 and the third switcher 36 in FIG. 3) have the same configuration. Can also be applied.

In FIG. 5, the M-axis voltage target value V _M ^* and the T-axis voltage target value V _T ^* are input to the absolute value calculator 42, and the armature voltage target value calculated by the absolute value calculator 42 is obtained. The magnitude (the armature voltage absolute value V _aABS ) is an input signal to the function unit 43. The M-axis voltage target value V _M ^* and the T-axis voltage target value V _T ^* are obtained from the output of the current regulator 29 in FIG. 6, for example.
The function set in the function unit 43 is the same as that of the function unit 37 in the third embodiment of FIG. 4 except for the input signal, and the subsequent configuration and operation are also the same as in the third embodiment.

According to the present embodiment, it is possible to obtain the magnetic flux calculation value Φ ₀ that smoothly changes according to the armature voltage absolute value _VaBS .
Since the armature voltage is substantially proportional to the product of the rotation speed and the armature flux linkage, an operation of switching the magnetic flux calculation value Φ ₀ may be performed by a signal of this product.

Although not shown, instead of the absolute velocity value ω _rABS in the third embodiment and the armature voltage absolute value _VaBS in the fourth embodiment, the magnetic flux calculation value Φ ₀ can be switched depending on the output frequency of the power converter. It is.
As described above, these switching operations can be applied not only to the magnetic flux calculation value Φ ₀ but also to the switching of the angle δ ₀ and the magnetic flux calculation value target value Φ ₀ ^* .

1, 1A Magnetic flux calculator 10, 26, 30 Coordinate converter 12, 13, 37, 43 Function unit 14, 15 Amplifier 18, 32 Vector calculator 11, 16, 17, 19, 23, 25, 27, 28, 40 , 41 Adder / Subtractor 20 Magnetic flux controller 21 Cosine function unit 22 Divider 24 Field current regulator 29 Current regulator 31 2-phase / 3-phase converter 33, 42 Absolute value calculator 34, 35, 36, 44 Switch 38 , 39 Multiplier

Claims (4)

In the vector control device of a synchronous motor that treats the magnetic flux and current of a field winding type synchronous motor as a vector and controls the armature current and the field current by a power converter,
When the rotational speed of the motor is lower than a predetermined value, the steady value of the armature current component parallel to the air gap magnetic flux vector is controlled to zero,
A vector control device for a synchronous motor, wherein a steady-state value of an armature current component parallel to an armature flux linkage vector is controlled to zero at a high speed when the rotation speed of the motor is equal to or higher than a predetermined value. In the synchronous motor vector control device according to claim 1,
When the rotational speed of the electric motor is lower than a predetermined value, the air gap magnetic flux is controlled so that the magnitude of the air gap magnetic flux vector matches the first target value,
When the rotational speed of the motor is higher than a predetermined value, the armature flux linkage is set so that the magnitude of the armature flux linkage vector coincides with a second target value smaller than the first target value. A vector control device for a synchronous motor, characterized by controlling. In the synchronous motor vector control device according to claim 2,
When the rotational speed transitions from low speed to high speed or from high speed to low speed,
Continuously changing the target value of the magnitude of the magnetic flux vector from the first target value to the second target value or from the second target value to the first target value; and
Calculate the magnetic flux vector magnitude from the gap magnetic flux vector magnitude calculation value to the armature flux linkage vector magnitude calculation value, or from the armature linkage flux vector magnitude calculation value. A vector control device for a synchronous motor, which is continuously changed to a calculated value of the magnitude of a magnetic flux vector. In the synchronous motor vector control device according to claim 1,
A vector control device for a synchronous motor, wherein an armature voltage of the motor is used instead of the rotation speed.

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