JPH11275900A - Controller of synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the accuracy in control by removing errors in the control of torque or terminal voltage, based on the error in positional detection of a synchronous motor. SOLUTION: The position of a rotor is compensated by a position compensator 19 so that the deviations between the magnitude of the voltage command value operated from the motor constant, velocity, and direct-axis current command values of a synchronous motor 3 and the quadrature axis current command value and the magnitude of the voltage obtained by the detection or operation of the terminal voltage is zero is given to first and second coordinate converters 10 and 13 and is used for controlling. Hereby, the value of the position of the rotor used for control is compensated properly, and the terminal voltage of the synchronous motor 3 is controlled to the value when there is no error in the position-detected value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor control device for controlling the speed of a synchronous motor using a power converter.

[0002]

2. Description of the Related Art Synchronous motors are AC motors that can only operate at a constant speed (synchronous speed) determined by the number of magnetic poles unique to the machine and the frequency of the AC circuit. A permanent magnet synchronous motor using a permanent magnet as a field of a rotating field synchronous motor is widely used. In the speed control of the synchronous motor, it is necessary to detect the position of the rotor, so that a position detector is attached in addition to the speed detector.

FIG. 7 shows a configuration example of a control device for a permanent magnet synchronous motor according to the prior art. In FIG. 7, a power converter 1 converts power from a commercial AC power supply 2 and supplies the converted power to a synchronous motor (PM motor) 3. The position detector 4 is attached to the synchronous motor 3 and outputs a position detection value θ. Coordinate converter 10, the phase current detection value i _u from the current detector 11, based on the i _v and the position detection value theta, it calculates the direct axis current detection value i _d and the quadrature axis current detection value i _q.

[0004] The current regulator 12 detects a direct-axis current detection value i._dPassing
And horizontal axis current detection value i_qIs the command value i _d ^*, i_q ^*To each
The linear axis voltage command value v_d ^*And horizontal axis voltage command
Value v_q ^*Is output. The coordinate converter 13 calculates the direct-axis voltage command value.
v_d ^*, Horizontal axis voltage command value v_q ^*, The phase voltage
Quotation v_u ^*, v_v ^*, v_w ^*, And thereby the PWM modulator
14 controls the power converter 1. As a result,
Control is performed such that the current of the motive 3 matches the command value,
Speed ω is the command value ω^*Is controlled to match.

[0005]

However, the position detection value θ contains an error due to a mechanical error when the position sensor is attached and a detection delay by the detection circuit. Due to this error, an error occurs in the calculations in the coordinate converters 10 and 13, and the current phase cannot be accurately controlled, and a control error occurs in the torque and the terminal voltage.

In particular, at the time of high-speed operation, the power converter 1 is operated near its maximum voltage, and the margin of the voltage is small, so that it is greatly affected by the terminal voltage error. For example, if the terminal voltage becomes larger than the planned value due to an error, the terminal voltage will be saturated at the maximum voltage of the power converter.
Current control may become unstable, torque pulsation may increase, or control may not be possible.

Further, when the terminal voltage becomes smaller than the planned value due to an error, in order to obtain a desired output, it is necessary to increase the current by an amount corresponding to the decrease in the voltage. This causes a decrease in efficiency, and a desired output may not be obtained due to current limitation of the power converter.

Accordingly, the present invention provides and uses a synchronous motor control device capable of compensating for the influence of the position detector error and improving the terminal voltage control accuracy.

[0009]

According to the present invention, in a control device for controlling the speed of a synchronous motor, if there is a position detection error by a position detector, the effect appears as a change in the magnitude of the terminal voltage. It pays attention to. That is, in the inventions according to claims 1 to 3, the motor constant, the speed,
The rotor position corrected so that the deviation between the magnitude of the voltage command value calculated from the direct axis current command value and the horizontal axis current command value and the magnitude of the voltage obtained by the terminal voltage detection or calculation becomes zero. Used for control. As a result, the value of the rotor position used for control is appropriately corrected, and the terminal voltage of the synchronous motor is controlled to a value when there is no error in the position detection value.

According to the present invention, the motor constant, the speed, the direct-axis current command value, the magnitude of the voltage command value calculated from the horizontal-axis current command value, and the magnitude of the voltage obtained by the terminal voltage detection or calculation. The phase of the current command value is corrected so that the deviation from the current command value becomes zero, and the current of the synchronous motor is controlled to match the current command value whose phase has been corrected. Thus, the terminal voltage of the synchronous motor is controlled to a value when there is no error in the position detection value.

According to the fifth aspect of the present invention, the deviation between the magnitude of the voltage command value calculated from the product of the speed and the flux linkage and the magnitude of the voltage obtained by the terminal voltage detection or calculation becomes zero. In this way, the command value of the flux linkage is corrected, and the current command value is obtained based on the corrected command value of the flux linkage.
This interlinkage magnetic flux command value is corrected so as to generate the same terminal voltage as when there is no error in the position detection value. Therefore,
A current command value that generates the same terminal voltage as when there is no error in the position detection value is obtained. By controlling the current of the synchronous motor so as to match the current command value obtained in this way, the terminal voltage of the synchronous motor is controlled to a value when there is no error in the position detection value.

That is, according to the present invention, even when there is an error in the position detection value, highly accurate control of the terminal voltage and the torque becomes possible. As a result, the following effects can be obtained. 1) Since the control accuracy of the torque is increased, the control performance of the synchronous motor can be improved. 2) Since the terminal voltage can be controlled below the maximum output voltage of the power converter, the terminal voltage does not saturate at the maximum voltage of the power converter, and the current control system can be stabilized. 3) Since the power converter can be used up to its maximum output voltage, the current can be reduced accordingly, and the efficiency and capacity of the power converter can be increased. 4) The above effect is particularly large during high-speed operation.
The operating speed range of the synchronous motor can be expanded.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, the configuration of the control device for a permanent magnet synchronous motor according to the first embodiment will be described with reference to FIG.
In FIG. 1, a power converter 1 converts AC power from a commercial AC power supply 2 and supplies power of a desired frequency to a synchronous motor (PM motor) 3. The synchronous motor 3 is provided with a position detector 4 for detecting a rotor position and a speed detector 5 for detecting a rotation speed.

The comparator 6 has a speed command value ω^*And speed detector
5 and outputs the deviation from the detected speed value ω.
The speed controller 7 inputs the deviation from the comparator 6 and
Amplify and torque command value τ^*Is output. Linkage flux command
The calculator 8 calculates a torque command value τ from the speed controller 7.^*And speed
From the speed detection value ω from the detector 5, the linkage flux command value ψ_a ^*
Is calculated and output. Here, the terminal voltage of the synchronous motor 3 is
Since the magnitude is approximately the product of the linkage flux and the velocity,
In order for the terminal voltage to be equal to or less than the maximum voltage of the power converter 1,
Linkage flux command value ψ_a ^*Is calculated.

The current command calculator 9 inputs the torque command value tau ^* and flux linkage command value [psi _a ^*, and outputs the direct-axis current command value i _d ^* and quadrature axis current command value i _q ^*. The detailed configurations of the flux linkage command calculator 8 and the current command calculator 9 are disclosed in, for example, the 1997 IEEJ National Convention 4-350, 1000.

The voltage command calculator 15 receives the speed detection value ω from the speed detector 5, the direct axis current command value _id ^* and the horizontal axis current command value _iq ^* from the current command calculator 9, and Using the set motor constants, the magnitude _vaM of the voltage command value is calculated according to Equation 1. In Equation 1, L _d
Is the d-axis inductance, L _q is the q-axis inductance, ψ _m
Is a no-load linkage magnetic flux, and r is a resistance.

[0017]

(Equation 1)

The voltage calculator 16 receives the terminal voltages v _uv and v _vw of the synchronous motor 3 detected by the voltage detector 17 and outputs _a voltage magnitude va. The comparator 18 outputs the deviation e between the size v _aM of this value v _a voltage command value. The position corrector 19 amplifies the deviation e and outputs a position correction value △ θ. The position corrector 19 receives the speed detection value ω and the torque command value τ ^* .

When the magnitude of the current is small, the range in which the magnitude of the voltage can be corrected by correcting the position is small, and the calculation of the position corrector 19 may not converge. Therefore, enter the direct-axis current command value i _d ^* and the horizontal-axis current command value i _q ^* on the current computing unit 20, a ^* size i _a current command value obtained by calculation of the equation 2, the position correcting this Is input to the container 19.

[0020]

(Equation 2)

The position corrector 19 performs the operation shown in the flowchart of FIG. In step 501, if ^* the size i _a current command value is less than the predetermined value i _amin, the process proceeds to step 502, sets the position correction value △ theta = 0, no correction of the position. This solves the problem that the operation of the position corrector 19 may not converge.

[0022] In step 501, if ^* the size i _a current command value is larger than the predetermined value i _amin, Step 5
In step 03, a position correction value △ θ is obtained. Polarity of the deviation e between the magnitude v _aM size v _a voltage command value of the voltage to be generated for error in the position detection value θ varies depending on the polarity of the torque. Therefore, the polarity of the gain of the position corrector 19 is switched according to the polarity sgn (τ ^* ) of the torque command value τ ^* . Also, as the speed ω is high, since the deviation e between the magnitude v _aM size v _a voltage command value of the voltage to be generated for error in the position detection value θ increases, the position corrector 1
The gain of No. 9 is used as a decreasing function K _p (ω) of the speed ω to stabilize the control system.

Next, the routine proceeds to step 504, where the position correction value △
The calculation result of θ is delayed by the first-order lag filter. This is to eliminate a calculation error caused by not taking into account the transient phenomenon of the current control system in the calculation of the voltage command value magnitude _vaM according to Equation 1.

[0024] Returning to FIG. 1, the adder 21 adds the position correction value △ theta from the position corrector 19 to the position detection value theta from the position detector 4 outputs the position calculated value theta _M. A coordinate converter 10 as a first coordinate conversion unit includes a current detector 11
Phase current detection value i _u from, i _v and enter the position calculated value theta _M from the adder 21 calculates and outputs the direct-axis current detection value i _d and the quadrature axis current detection value i _q. The current controller 12 determines that the detected value of the direct axis current _id and the detected value of the horizontal axis current _iq are the command values _id ^*,
i _q ^* on to match, and outputs the direct axis voltage command value v _d ^* and the horizontal-axis voltage command value v _q ^*. The coordinate converter 13 as the second coordinate conversion means uses the direct-axis voltage command value v _d ^* , the horizontal-axis voltage command value v _q ^*, and the position calculation value θ _M to calculate the phase voltage command values v _u ^*, v _v ^* , Calculate v _w ^* and provide it to the PWM modulator 14. The PWM modulator 14 generates a control signal based on pulse width modulation, and controls the power converter 1 based on the control signal.

Next, the operation of this embodiment will be described. Now, it is assumed that an error has occurred in the position detection value θ due to a mechanical error when the position sensor is attached and a delay of the detection circuit. Conversion and conversion of the voltage command value of the current detection value at the coordinate converter 10 and 13 is performed using the position calculated value theta _M as described above. Here, the position calculation value θ _M is corrected by the position correction value Δθ from the position corrector 19 so as to generate the same terminal voltage as when the position detection value θ has no error. Therefore, instead of the position detection value θ from the position detector 4 including the error, the position calculation value θ _M is
By using at 0 and 13, the terminal voltage of the synchronous motor 3 is accurately controlled. As a result, even when there is an error in the position detection value θ, highly accurate control of the terminal voltage and the torque of the synchronous motor 3 can be performed without being affected by the error.

Next, the configuration of a second embodiment of the present invention will be described with reference to FIG. In the first embodiment shown in FIG. 1, the voltage operation magnitude v _a is carried out based on a value detected by the voltage detector 17, in the embodiment shown in FIG. 2, the magnitude v _a voltage The calculation is performed approximately using the direct-axis voltage command value v _d ^* and the horizontal-axis voltage command value v _q ^* , and the voltage detector is omitted. In FIG. 2, components common to FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The voltage calculator 25 receives the direct-axis voltage command value v _d ^* and the horizontal-axis voltage command value v _q ^* from the current controller 12,
Obtaining a magnitude v _a voltage by performing the operation expressed by Equation 3.

[0028]

(Equation 3)

The comparator 18 inputs the magnitude of v _aM of the voltage command value from the magnitude v _a and the voltage command calculator 15 of the voltage from the voltage calculator 25, and outputs the deviation e. The position corrector 19 amplifies the deviation e and outputs a position correction value △ θ.

In this embodiment, it is assumed that an error has occurred in the position detection value θ due to a mechanical error when the position sensor is attached and a delay in the detection circuit. The error of the position detection value θ appears as a change in the terminal voltage of the synchronous motor 3 as in the case of the first embodiment. Incidentally, the terminal voltage of the synchronous motor 3 is controlled by the direct-axis voltage command value v _d ^* and the horizontal-axis voltage command value v _q ^* from the current controller 12.

[0031] Therefore, even when performing position correction using the magnitude v _a voltage determined by calculation from this value,
As in the first embodiment, the terminal voltage of the synchronous motor 3 can be accurately controlled without being affected by an error included in the position detection value θ. In the second embodiment, since the voltage detector as in the first embodiment is not required, the cost of the control device can be reduced.

Next, the configuration of a third embodiment of the present invention will be described with reference to FIG. In this embodiment, the size v _a voltage to match the size of v _aM voltage command value, ^* current command value i _d, corrects the i _q ^* phase.

[0033] Similar to the embodiment shown in FIG. 2, calculates the magnitude of v _aM voltage command value by the voltage command calculator 15 calculates the magnitude v _a voltage by the voltage calculator 25. Comparator 18, the size of v _a voltage command value of the voltage magnitude v _aM
Is output. The phase corrector 30 calculates the deviation e
And outputs a phase correction value Δφ. Phase corrector 30
Uses a P adjuster based on a proportional element. In addition, the speed detection value ω and the torque command value τ ^* are input to the phase corrector 30.

When the magnitude of the current is small, the range in which the magnitude of the voltage can be corrected by correcting the current phase is small.
The operation of the phase corrector 30 may not converge. Therefore, enter the current computing unit 20 in the direct-axis current command value i _d ^* and quadrature axis current command value i _q ^*, a ^* size i _a current command value obtained by calculation of Equation 2 described above, it It is input to the phase corrector 30.

In the phase corrector 30, the calculation shown in the flowchart of FIG. 6 is performed. Step 6 in FIG.
In 01, the current command value magnitude i _a ^* is a predetermined value i _amin
In the following cases, the process proceeds to step 602, where the phase correction value Δφ =
Set to 0, no phase correction. This solves the problem that the operation of the phase corrector 30 may not converge.

If the magnitude of the current command value i _a ^* is larger than the predetermined value i _{amin in} step 601, step 6
In step 03, a phase correction value 位相 φ is obtained. Size v _aM size v _a voltage command value of the voltage to be generated for error of the phase
Is different depending on the polarity of the torque. Therefore, the polarity of the gain of the phase corrector 30 is switched according to the polarity sgn (τ ^* ) of the torque command value τ ^* . Also, as the speed ω is higher, the magnitude of the voltage v _a and the magnitude of the voltage command value v with respect to the error of the position detection value θ are increased.
_Since the deviation e from _aM becomes large, the gain of the phase corrector 30 is set to a decreasing function K _p (ω) of the speed ω, and the control system is stabilized.

Next, the routine proceeds to step 604, where the position correction value △
The calculation result of φ is delayed by the first-order lag filter. This is to eliminate a calculation error caused by not taking into account the transient phenomenon of the current control system in the calculation of the voltage command value magnitude _vaM according to Equation 1.

Returning to FIG. 3, the phase converter 31 receives the direct-axis current command value _id ^* and the horizontal-axis current command value _iq ^*, and corrects the phase by a position correction value Δφ. To calculate the corrected current command values _id ^** , _iq ^** . The operation performed in the phase converter 31 is represented by Expression 4.

[0039]

(Equation 4)

The coordinate transformer 10, the current phase current detection value i _u from the detector 11, and inputs the detected position value θ from the i _v and the position detector 4, the direct-axis current detection value i _d and the quadrature axis current Detection value _iq
Is calculated and output. Current regulator 12, the direct-axis current detection value i _d and the quadrature axis current detection value i _q is corrected current command value i
_d ^**, to match each i _q ^**, and outputs the direct axis voltage command value v _d ^* and the horizontal-axis voltage command value v _q ^*.

Next, the operation of this embodiment will be described. Electric
The control of the current by the flow regulator 12 has its phase corrected.
Current command value i_d ^**And i_q ^**This is done using here
And the current command value i_d ^**And i_q ^**Is the error in the position detection value θ.
To generate the same terminal voltage as when there is no
It is corrected by the phase correction value △ φ from the corrector 30.
Then, the current of the synchronous motor 3 is controlled by the current controller 12.
Current command value i_d ^*And i _q ^*Is controlled to match.
That is, the current phase is accurately controlled. As a result,
The terminal voltage of the initial motor 3 is set when there is no error in the detected position
It is controlled to the value of the case. Therefore, there is an error in the position detection value θ.
The synchronous motor 3
The terminal voltage and the torque can be controlled with high accuracy.

Next, the configuration of the fourth embodiment of the present invention will be described.
This will be described with reference to FIG. In this embodiment, as the size v _a voltage matching the magnitude v _aM voltage command value,
The flux linkage command value ψ _a ^* is corrected.

In FIG. 4, a multiplier 40 calculates the product of the flux linkage command value ψ _a ^* output from the flux linkage command calculator 8 and the speed detection value ω from the speed detector 5 to calculate the voltage. The command value is output as the magnitude _vaM . The voltage calculator 25 calculates the magnitude v _a of the voltage according to the above-described equation (3). Comparator 4
1 outputs the deviation e between the size v _aM size v _a voltage command value of the voltage. The flux linkage corrector 42 amplifies the deviation and outputs _a flux linkage correction value △ ψ _a ^* .

The gain of the linkage flux compensator 42 is a decreasing function of the speed. The deviation e between the size v _aM size v _a voltage command value of the voltage with respect to the position detection error is because increases in proportion to the speed, which makes it possible to stabilize the control system. Furthermore, the linkage flux correction value △ ψ
_The result of _a ^* is delayed by the first-order lag filter. This is to eliminate a calculation error caused by not taking into account the transient phenomenon of the current control system in the calculation of the magnitude _vAM of the voltage command value according to Equation 1.

The adder 43, flux linkage command value [psi _a ^* to the flux linkage correction value △ [psi _a ^* by adding outputs the corrected flux linkage command value [psi _a ^**. The current command calculator 9 receives the torque command value τ ^* from the speed controller 7 and the corrected flux linkage command value ψ _a ^** from the adder 43 and inputs the direct-axis current command value _id
^{* And the} horizontal axis current command value _iq ^* are output.

Next, the operation of this embodiment will be described. Calculation of the current command value by the current command calculator 9 is performed using the corrected flux linkage command value [psi _a ^**. Here, the flux linkage command value ψ _a ^** is generated by the flux linkage corrector 42 so as to generate the same terminal voltage as when the position detection value θ has no error.
Is corrected by the interlinkage magnetic flux correction value か ら_a ^* . For this reason, the position detection value θ is calculated by the current command calculator 9.
, The current command values _id ^* and _iq ^* that generate the same terminal voltage as in the case where there is no error can be obtained.

Then, by the operation of the current regulator 12, the current of the synchronous motor 3 is controlled so as to match the current command values _id ^* and _iq ^* . As a result, the terminal voltage of the synchronous motor 3 is controlled to a value when there is no error in the position detection value θ.
Therefore, even when there is an error in the position detection value θ, highly accurate control of the terminal voltage and the torque of the synchronous motor 3 can be performed without being affected by the error.

[0048]

As described above, according to the present invention, there is provided a control device for a synchronous motor capable of controlling terminal voltage and torque with high accuracy even when there is an error in a detected value of a rotor position. The present invention is also applicable to a DC-excited synchronous motor controller without using a permanent magnet as a field.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a control device for a synchronous motor according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a control device for a synchronous motor according to a second embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a control device for a synchronous motor according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a control device for a synchronous motor according to a fourth embodiment of the present invention.

FIG. 5 is a flowchart showing a calculation executed in the position corrector of FIG. 1;

FIG. 6 is a flowchart showing an operation performed in the phase corrector of FIG. 3;

FIG. 7 is a block diagram illustrating a configuration of a control device for a synchronous motor according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power converter 2 Commercial AC power supply 3 Synchronous motor 4 Position detector 5 Speed detector 6, 18, 41 Comparator 7 Speed controller 8 Linkage flux command calculator 9 Current command calculator 10, 13 Coordinate converter 11 Current Detector 12 Current controller 14 PWM modulator 15 Voltage command calculator 16, 25 Voltage calculator 17 Voltage detector 19 Position corrector 20 Current calculator 21, 43 Adder 30 Phase corrector 31 Phase converter 40 Multiplier 42 Linkage flux compensator

Claims (5)

[Claims] 1. A position detecting means for detecting a rotor position of a synchronous motor, a current command calculating means for generating a direct axis current command value and a horizontal axis current command value, a detected value of a motor current and a rotor of the synchronous motor. First coordinate conversion means for calculating a direct axis current detection value and a horizontal axis current detection value based on the position; and the direct axis current command value, the horizontal axis current command value, the direct axis current detection value, and the horizontal axis current. Current adjusting means for generating a direct-axis voltage command value and a horizontal-axis voltage command value so that the detected values respectively correspond to each other; Based on the second, the phase voltage command value is calculated based on the
A synchronous command motor, comprising: a synchronous motor control device for calculating a magnitude of a voltage command value from a motor constant, a speed, the direct-axis current command value, and the horizontal-axis current command value; Voltage calculation means for calculating the magnitude of the voltage proportional to the terminal voltage of the voltage control means; position correction means for calculating a position correction value based on a deviation between the magnitude of the voltage command value and the output of the voltage calculation means; A means for providing the calculated position value corrected by the value to the first and second coordinate conversion means as a rotor position, and a control device for the synchronous motor. 2. The synchronous motor control device according to claim 1, further comprising voltage detecting means for detecting a terminal voltage of the synchronous motor, wherein the voltage calculating means calculates a voltage proportional to the terminal voltage from a detected value of the terminal voltage. A control device for a synchronous motor, wherein the control device calculates a size of the motor. 3. The synchronous motor control device according to claim 1, wherein the voltage calculation means calculates a voltage magnitude proportional to a terminal voltage from the direct axis voltage command value and the horizontal axis voltage command value. Characteristic synchronous motor control device. 4. A position detecting means for detecting a rotor position of the synchronous motor, a current command calculating means for generating a direct-axis current command value and a horizontal-axis current command value, a detected value of a motor current and a rotor of the synchronous motor. First coordinate conversion means for calculating a direct axis current detection value and a horizontal axis current detection value based on the position; and the direct axis current command value, the horizontal axis current command value, the direct axis current detection value, and the horizontal axis current. Current adjusting means for generating a direct-axis voltage command value and a horizontal-axis voltage command value so that the detected values respectively correspond to each other; Based on the second, the phase voltage command value is calculated based on the
A synchronous command motor, comprising: a synchronous motor control device for calculating a magnitude of a voltage command value from a motor constant, a speed, the direct-axis current command value, and the horizontal-axis current command value; Voltage calculation means for calculating the magnitude of the voltage proportional to the terminal voltage of the voltage control means; phase correction means for calculating a current phase correction value based on a deviation between the magnitude of the voltage command value and the output of the voltage calculation means; The phases of the direct-axis current command value and the horizontal-axis current command value from the current-command calculating means are shifted by the current phase correction value, and the corrected direct-axis current command value and horizontal-axis current command value are adjusted. A control device for a synchronous motor, comprising: 5. A position detecting means for detecting a rotor position of a synchronous motor; a current command calculating means for generating a direct axis current command value and a horizontal axis current command value from a linkage flux command value and a torque command value; First coordinate conversion means for calculating a direct-axis current detection value and a horizontal-axis current detection value based on the detected current value and the rotor position of the synchronous motor; and the direct-axis current command value and the horizontal-axis current command value. Current-control means for generating a direct-axis voltage command value and a horizontal-axis voltage command value such that the current value of the direct-axis current and the detected value of the horizontal-axis current respectively match; Calculating a phase voltage command value based on the value and the rotor position of the synchronous motor.
A synchronous command control device having a coordinate conversion means of: a voltage command calculating means for calculating the magnitude of the voltage command value from a product of the flux linkage command value and the speed; Voltage calculation means for calculating the magnitude; linkage flux correction means for calculating a correction value of the flux linkage command value based on a deviation between the magnitude of the voltage command value and the magnitude of the voltage; and the linkage flux command value. A flux linkage command calculating means for providing the flux linkage command value corrected by the correction value to the current command calculation means.