JPH06273496A - Method and apparatus for measuring constant of motor - Google Patents

Abstract

PURPOSE:To accurately measure a constant of a motor in a state that rotation of the motor is stopped. CONSTITUTION:A primary angular frequency command omega1* and a primary voltage command V1q* are set to '0' according to a measurement signal from a motor constant calculator 7, and a signal in which a DC bias is superposed on an AC signal is output as a command value of a d-axis. When this signal is input to a coordinate transformer 3 and transformer to a three-phase voltage command signal, a signal for supplying a single-phase AC current to an AC motor 1 is output from an inverter 2. That is, a current flows to the motor 1 in a state that rotation of the motor 1 is stopped. When this current is detected by current detectors 4a, 4b and this detection current is input to a coordinate transformer 5, current components I1q, I1d are output from the transformer 5. The component I1d of the d-axis is analyzed by a Fourier expansion, and a constant of the motor is calculated according to a Fourier series of its fundamental wave component and a command value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor constant measuring method and an apparatus therefor, and more particularly to an electric motor constant measuring method and an apparatus suitable for measuring an electric motor constant required in a control device for vector-controlling an AC electric motor.

[0002]

2. Description of the Related Art When controlling an AC electric motor using a vector controller, it is necessary to set a control constant based on the constant of the target AC electric motor. Therefore, conventionally, a method of setting a control constant based on a design value of a motor constant, or measuring a necessary motor constant by a resistance measurement test, a no-load test, a constraint test, and setting a control constant from this measurement result Has been adopted.

However, in the former method of setting based on the design value of the electric motor, a control calculation error occurs due to the mismatch between the design value and the actual value, and the readjustment is unavoidable after setting the control constant.

On the other hand, the latter method, which is set based on the measurement results obtained by various measurement tests, satisfies the conditions for performing various measurements, such as the need for an instrument for fixing the motor in the restraint test. The preparation work for doing so becomes complicated.

Therefore, as a means for dealing with these problems, there is one described in Japanese Patent Application Laid-Open No. 62-262697. This is to find the voltage command value and the current detection value in the steady state when various measurement conditions are given with the motor connected to the inverter control device, and follow these values and the voltage equations of the d and q axes of the motor. The motor constant is measured, and the control constant is set according to the measurement result.

[0006]

However, in the prior art, it is not possible to maintain the rotation stop state of the motor because a three-phase alternating current flows through the motor during measurement and torque is generated. If the electric motor rotates during the measurement, the measurement accuracy deteriorates and an accurate value cannot be obtained as the electric motor constant. Further, if the measurement is performed with a very small signal such that the electric motor does not rotate, the measurement accuracy is similarly deteriorated due to the influence of harmonic components and noise of the inverter.

An object of the present invention is to provide an electric motor constant measuring method and apparatus capable of accurately measuring the electric motor constant while the rotation of the electric motor is stopped.

[0008]

In order to achieve the above object, the present invention generates a three-phase voltage command signal according to a d-axis voltage command, a q-axis voltage command, and a primary angular frequency command, and in proportion thereto. While controlling the output voltage of the power converter and applying it to the motor, the output current of the inverter is detected, and when detecting the d-axis current component and the q-axis current component according to the detected current and the primary angular frequency command, the primary angular frequency Under the condition that each command value of the command and the q-axis voltage command is set to zero, an AC signal is given as the command value of the d-axis voltage command, and the converter output voltage according to the three-phase voltage command signal generated based on this is given. The motor constant measuring method is characterized in that the d-axis current component flowing in the motor at this time is detected and the constant of the motor is obtained based on the detected value.

Further, according to the present invention, a three-phase voltage command signal is generated according to the d-axis voltage command, the q-axis voltage command, and the primary angular frequency command, and the output voltage of the power converter is controlled in proportion thereto and applied to the electric motor. In addition, when detecting the output current of the inverter and detecting the d-axis current component and the q-axis current component according to the detected current and the primary angular frequency command, the respective command values of the primary angular frequency command and the d-axis voltage command are set to zero. Under the condition, the AC signal is given as the command value of the q-axis voltage command,
The converter output voltage according to the three-phase voltage command signal generated based on this is applied to the electric motor, the q-axis current component flowing in the electric motor at this time is detected, and the constant of the electric motor is obtained based on this detected value. The motor constant measurement method described below is adopted.

In each of the above measuring methods, when an AC signal is given as a command value and a converter output voltage according to a three-phase voltage command signal generated based on the command signal is applied to the electric motor, a d-axis current component flowing in the electric motor or The q-axis current component is detected, the detected value is analyzed according to the Fourier expansion by the trigonometric function with the AC signal as a reference, and the constant of the electric motor can be obtained based on the Fourier coefficient of the fundamental wave component and the AC signal value. desirable.

In each of the above measuring methods, it is desirable to use a signal in which a DC bias is superimposed on an AC signal as the voltage command value.

Further, based on the motor constants obtained by any of the above measuring methods, a d-axis voltage command and a q-axis voltage command based on the q-axis current command, the exciting current command, the q-axis current component and the d-axis current component. And set the control constant of the vector controller for generating the primary angular frequency command.

The present invention also provides, as a first device, three-phase voltage command signal generating means for generating a three-phase voltage command signal in accordance with a d-axis voltage command, a q-axis voltage command and a primary angular frequency command, and the three-phase voltage command. A power converter that applies an AC voltage proportional to the command to the electric motor, an output current detection unit that detects an output current of the power converter, a detection current of the output current detection unit, and a d-axis current component according to the primary angular frequency command. A current component generating means for generating a q-axis current component, a primary angular frequency command and q
As a result of applying the measurement signal generating means for setting each command value of the axis voltage command to zero and giving an AC signal as the command value of the d-axis voltage command, and the three-phase AC voltage changing according to the AC signal to the motor. A motor constant measuring device comprising: a motor constant calculating means for calculating a constant of the motor based on the d-axis current component detected by the current component generating means.

As a second device, a d-axis voltage command and q
Three-phase voltage command signal generating means for generating a three-phase voltage command signal according to the shaft voltage command and the primary angular frequency command, a power converter for applying an AC voltage proportional to the three-phase voltage command to the electric motor, and the power converter Output current detecting means for detecting the output current of the output current detecting means, current component generating means for generating the d-axis current component and the q-axis current component according to the detected current of the output current detecting means and the primary angular frequency command, the primary angular frequency command and the d-axis A measurement signal generating means for setting each command value of the voltage command to zero and giving an AC signal as a command value of the q-axis voltage command;
A motor having a motor constant calculating means for calculating a constant of the motor based on the q-axis current component detected by the current component generating means as a result of the three-phase AC voltage changing according to the AC signal being applied to the motor. This is a configuration of a constant measuring device.

In each of the measuring devices, it is preferable that the measurement signal generating means is configured to generate a signal in which a DC bias is superimposed on an AC signal as a command value of the voltage command.

[0016]

According to the above-mentioned means, the primary angular frequency command and q
Set each command value of the axis voltage command to zero and give an AC signal as the command value of the d-axis voltage command, or set each command value of the primary angular frequency command and the d-axis voltage command to zero, and set the q-axis voltage command to The measurement condition is to give an AC signal as a command value. If you measure according to any of the measurement conditions, the three-phase AC current does not flow in the motor winding,
Since the V-phase and W-phase currents are in the same phase and a single-phase AC current flows, the electric motor can be maintained in a stopped state without rotating. Then, when the rotation of the electric motor is stopped, a d-axis current component or a q-axis current component flowing in the electric motor is detected, and the detected value is analyzed according to a Fourier expansion by a trigonometric function with the AC signal as a reference. Since the constant of the electric motor is obtained on the basis of the Fourier coefficient of the wave component and the AC signal value, an accurate electric motor constant can be obtained. In this case, the constant of the electric motor can be obtained based on the detected value of the d-axis current component or the q-axis current component flowing in the electric motor.

On the other hand, when a signal in which a DC bias is superimposed on an AC signal is used as the command value of the voltage command when obtaining the motor constant, the influence of the d-axis or q-axis voltage distortion due to the on-delay of the power converter is used. Can be removed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram showing an embodiment when the motor constant measuring method of the present invention is applied to a system for driving an AC motor by a PWM inverter. In FIG. 1, a PWM inverter 2 is connected to the AC motor 1 to be measured. The PWM inverter 2 is provided with a switching element such as a thyristor, and a PWM signal for generating a three-phase PWM signal by comparing the three-phase voltage command signals V ₁ u *, V ₁ v *, V ₁ w * with a carrier wave. A generator is provided, and an AC signal having a variable frequency is supplied to the AC motor 1 according to the PWM signal. The three-phase voltage command signals V ₁ u * to V ₁ w * are generated by the coordinate converter 3. This coordinate converter 3 uses a primary voltage command V ₁ d * as a d-axis voltage command, V ₁ q * as a q-axis voltage command, and a primary angular frequency command ω ₁ according to the following equation (1).
The three-phase voltage command signals V ₁ u *, V ₁ v *, and V ₁ w * are calculated from *.

[0019]

[Equation 1]

On the other hand, the PWM inverter 2 and the AC motor 1
A current detector 4 for detecting the U-phase current in the line connecting to
A current detector 4b for detecting the currents of the a and W phases is provided, and the detected current of each detector is supplied to the coordinate converter 5. The coordinate converter 5 uses the detected currents of the current detectors 4a and 4b and the primary angular frequency command ω ₁ * according to the following equation (2) to generate a biaxial d-axis current component I ₁ d represented by d and q axes, q
It is configured as a current component generating means for generating the axial current component I ₁ q, and a signal relating to each current component is supplied to the vector controller 6 with an autotuning function.

[0021]

[Equation 2]

The vector controller 6 comprises a motor constant calculator 7, a control constant calculator 8, and a vector controller 9. The electric motor constant calculator 7 constitutes electric motor constant calculating means for calculating a constant of the electric motor based on the current component I ₁ d from the coordinate converter 5, and also has a primary angular frequency command ω ₁ * and a d-axis voltage command V ₁ Each command value of d * is set to 0, and the command signal of the q-axis voltage command V ₁ q * is configured as a measurement signal generating unit that generates a signal in which a DC bias is superimposed on an AC signal. The control constant calculator 8 is
The control constant of the vector controller 9 is calculated based on the electric motor constant calculated by the electric motor constant calculator 7. The vector controller 9 controls the primary voltage commands V ₁ d * and V ₁ q according to the control constant calculated by the control constant calculator 8.
It is configured to control signals such as *, the primary angular frequency command ω ₁ * and the like.

Here, considering the PWM inverter 2 before measuring the motor constant of the AC motor 1, the PWM inverter 2 is controlled so that the switching elements on the positive side and the negative side are alternately turned on and off according to the PWM signal. At this time, the PWM signal is provided with an on-delay time in order to prevent a DC short circuit of the switching element. During this on-delay period, since the output current flows through the diode on the positive side or the negative side according to the polarity of the output current, a voltage drop similar to a resistance drop depending on the polarity of the current (hereinafter, this Is an on-delay drop amount V ₀ ). Therefore, the output voltage of the inverter has a value different from the voltage command as it is.

Therefore, in this embodiment, as the measurement conditions, the primary angular frequency command ω ₁ * is 0 and the q-axis voltage command is 0.
Then, an AC signal (V ₁ d * = Vs + Vdsinωt) to which a DC bias is added as a command value of the d-axis voltage command is input to the coordinate converter 3, and a PWM signal according to this signal is applied to the inverter 2 for on-delay. Consider the effect of. In this case, when a signal according to the measurement conditions is input to the coordinate converter 3, the calculation formula in the coordinate converter 3 is the following formula (3) from the formula (1).

[0025]

[Equation 3]

From the equation (3), it is understood that the V phase voltage and the W phase voltage are in phase. When a current flows in each phase because the voltages of the W phase and the V phase become the same phase, the currents of the V phase and the W phase also become the same phase. At this time, since the drop component V ₀ due to on-delay corresponding to the polarities of the currents of the respective phases is added to the voltage command values of the three phases, if the voltages Vs and Vd are set such that the U-phase current is always positive, the inverter 2 The voltage actually output from is expressed by the following equation (4).

[0027]

[Equation 4]

When the three-phase inverter output voltage represented by the equation (4) is subjected to coordinate conversion on the d and q axes, it is represented by the following equation (5).

[0029]

[Equation 5]

As shown in the equation (5), the q-axis voltage V ₁
The effect of on-delay does not appear in q, and the q-axis voltage command V ₁ q * is 0 as set.

From the above relation, ω ₁ * is 0 and V ₁ q * is 0.
In the case of, the three-phase AC current does not flow in the winding of the AC motor 1, and the V-phase and W-phase currents have the same phase of the single-phase AC current. Therefore, even if a large measurement signal is applied to the d-axis, no torque is generated in the electric motor 1 and the rotation of the electric motor 1 is maintained in a stopped state.

Therefore, when the AC motor 1 is equivalently modeled by a block diagram, a model as shown in FIG. 2 is obtained. When the above measurement conditions are applied to this model, the motor speed ωre is 0 and the slip angular frequency is 0. ωs becomes 0. When this condition is applied to the model of FIG. 2, ωre is 0 and ωs is 0.
2 can be represented by the model of FIG. 3.

Looking at equation (5), the d-axis has an influence of on-delay (drop amount V ₀ due to on-delay), and an AC signal is input to the coordinate converter 3 as a command value of the d-axis voltage command. At times, as shown in FIG. 4A, a measurement result in which voltage distortion occurs was obtained. Therefore, the DC bias Vs and the amplitude Vd of the AC signal that do not convert the polarity of the output current of the inverter 2 are selected, and the AC signal according to these conditions is applied to the coordinate converter 3 for measurement. A voltage waveform as shown in (b) of FIG.

Next, according to the measurement conditions, the motor constant,
That is, the combined resistance of the primary and secondary (rσ = r ₁ + r ₂ ′),
The combined primary and secondary leakage inductance (Lσ = l ₁ +
l ₂ ′), primary resistance (r ₁ ), on-delay drop (V
₀ ), secondary resistance (r ₂ ′), and secondary time constant T ₂ ) will be described.

(Method for measuring rσ, Lσ, r ₁ , V ₀ ) First, V ₁ d * = Vs + Vd sin ωt is input to the coordinate converter 3 as a measurement signal, and a voltage according to this measurement signal is applied to the motor 1. At this time, the current flowing through the AC motor 1 is detected by the current detectors 4a and 4b, and the d-axis current component I ₁ d is generated according to the detected current. Then, the d-axis current component I ₁ d is Fourier expanded with the AC signal Vdsin ωt as a reference, and the direct current component and the fundamental wave component are noted and shown as the following equation (6).

[0036]

[Equation 6]

Here, the period T is 2π / ω. In addition,
It is possible to calculate the Fourier series not only in one cycle of integration but in any cycle.

By the way, as understood from the block diagram shown in FIG. 3, since the motor model at the time of measurement is linear, the output response to a DC signal and the output response to an AC signal are determined by the superposition theorem. You can think separately.

Therefore, first, the response to an AC signal will be considered. Here, the angular frequency ω of the measurement signal is 1 / T ₂
3 is sufficiently high, the output φ ₂ d of the block 24 shown in FIG. 3 can be regarded as 0, and V ₁ d * to I ₁ d
The transfer functions up to are expressed by the following equation (7).

[0040]

[Equation 7]

When the AC signal Vdsinωt is applied to the block 22 including the first-order lag element, the current I ₁ d output from the block 22 is expressed by the following equation (8).

[0042]

[Equation 8]

Of the fundamental wave components in equation (6), cos
The coefficient of ωt and the coefficient of cos ωt in equation (8) match,
Since the coefficient of sin ωt in the equation (6) and the coefficient of sin ωt in the equation (8) match, if an equation is made based on this condition, rσ and Lσ are expressed by the following equations (9) and (10). Be done.

[0044]

[Equation 9]

[0045]

[Equation 10]

In the equations (9) and (10), Vd can be obtained by the set value, and I ₁ d is the current detector 4
It can be obtained according to the detected values of a and 4b. Therefore, the motor constants rσ and Lσ can be measured according to the equations (9) and (10).

Next, the response to a DC signal will be considered. The transfer function from V ₁ d * to I ₁ d is (11)
It is represented by a formula.

[0048]

[Equation 11]

When a DC signal Vs (on-delay drop is included in the voltage actually applied) is added to the transfer function represented by the equation (11), the d-axis current generated by the coordinate converter 5 is generated. The component I ₁ d is represented by the following equation (12).

[0050]

[Equation 12]

The current I ₁ d expressed by the equation (12) is (6)
Since it matches the DC component of the equation, the equation for r ₁ and V ₀ is represented by the following equation (13).

[0052]

[Equation 13]

Since there are two unknown variables in the equation (13), r ₁ and V ₀ cannot be obtained as they are. Therefore,
The value of Vs is changed and a total of two measurements are performed. The second DC signal is Vs', and the current component obtained at this time is I
Assuming ₁ d ', r ₁ is expressed by the following equation (14).

[0054]

[Equation 14]

When V ₀ is expressed using r ₁ obtained according to the equation (14), V ₀ is given by the following equation (15).

[0056]

[Equation 15]

In equations (14) and (15), Vs and V
s'can be obtained as a set value, and I ₁ d, I ₁ d '
Can be obtained by measurement, and the motor constants r ₁ and V ₀ can be measured according to the equations (14) and (15).

(Measurement of r ₂ ′, T ₂ ) Next, the control constant of the current controller is set according to the rσ and Lσ measured by the above-mentioned method, and I ₁ d * is set as a measurement signal in this current controller.
= Is + Idsinωt is input, and I is set by the current controller.
Control is performed so that ₁ d becomes I ₁ d *. As a result, the voltage command value V ₁ d * appears at the output of the current controller. here,
When the angular frequency ω of the measurement signal is smaller than 1 / T2,
The output φ ₂ d of the block 24 cannot be regarded as 0,
The output Vf of block 26 will have an effect. Therefore, the transfer function from V ₁ d to Vf is given by the following expression (16).

[0059]

[Equation 16]

However,

[0061]

[Equation 17]

The voltage signal Vf is expressed by the following equation (18) from the equations (16) and (17) and the measurement signal.

[0063]

[Equation 18]

The voltage signal Vf expressed by the equation (18) is
It can be obtained from the voltage command value V ₁ d *, the on-delay drop amount V ₀ , the detected current value I ₁ d, and the previously measured rσ and Lσ.

Next, the voltage signal Vf is converted into the AC signal Vdsin.
When Fourier expansion is performed with ωt as a reference and the direct current component and the fundamental wave component are focused and shown, the following formula (19) is obtained.

[0066]

[Formula 19]

Here, as is apparent from the block diagram of FIG. 3, since the motor model at the time of measurement is linear, the output response to the DC signal and the output response to the AC signal are separated by the theorem of superposition. Can be thought of. Therefore, considering the response to the AC signal, when the AC signal Idsin ωt is added to the first-order lag element, the voltage signal Vf output from the block 26 is expressed by the following equation (20).

[0068]

[Equation 20]

In equations (19) and (20), cos ω
Since the coefficients of t and sinωt are the same, T ₂ and r ₂ ′ can be calculated by the following (2
It is expressed by equations (1) and (22).

[0070]

[Equation 21]

[0071]

[Equation 22]

In the equations (21) and (22), the current component I ₁ d and the voltage signal Vf can be obtained by measurement, and the motor constants T ₂ and r ₂ ′ are (21) and (22).
It can be measured according to the formula.

As described above, when measuring the electric motor constant, the influence of on-delay is included only in the direct current component and not in the term related to the electric motor constant, and therefore the direct current bias is superimposed on the alternating current signal as the measurement signal. By using the signal, various motor constants can be measured with high accuracy without being affected by the on-delay.

In the above embodiment, the one in which the measurement signal is applied to the d-axis has been described, but as shown in FIG. 3, since the d-axis and the q-axis are completely the same model, the measurement signal is applied to the q-axis. In addition, various motor constants can be measured. In this case, each command value of the primary angular frequency command ω ₁ * and the d-axis voltage command V ₁ q * is set to 0, and q
A signal in which a DC bias is superimposed on an AC signal is used as the command value of the shaft voltage command. In addition, even if a measurement signal of the same phase is added to the d-axis and the q-axis, the combined vector direction becomes a new axis,
For example, this axis is the d'axis, the axis orthogonal to this is the q'axis, and the d'and q'axes perform the same operations as in the above embodiment, so they can be treated equivalently. Further, in the above-mentioned embodiment, the case where the voltage which makes the current always positive is added as the DC bias has been described, but the same structure can be obtained by adding the DC bias which makes the current always negative.

The various motor constants obtained by the above-described measuring method are stored in the storage element and used for setting the control calculation constants of the inverter controller as shown in FIG.

In the vector controller shown in FIG. 5,
In addition to the PWM inverter 2, the coordinate converters 3, 5, and the current detectors 4a, 4b shown in FIG. 1, a speed detector 10, a speed commander 11, a speed controller 12, an exciting current commander 13, a current controller 14, 15, a slip angle frequency controller 16, a non-interference controller 17, and the like. The speed controller 12 is
A q-axis current command V ₁ q * corresponding to the difference between the speed command from the speed command device 11 and the detected speed from the speed detector 10 is generated. The current controller 15 is the speed controller 12
The q-axis voltage command V ₁ q * is output according to the deviation between the q-axis current command value I ₁ q * and the q-axis current component I ₁ q. The current controller 14 is adapted to generate a d-axis voltage command V ₁ d * according to a deviation between the exciting current command I ₁ d * from the exciting current command device 13 and the d-axis current component I ₁ d. . The slip angle frequency controller 16 uses q from the speed controller 12.
The axis current command I ₁ q * is divided by the current component I ₁ d * to generate the slip angular frequency command ωs *. Then, this slip angular frequency command ωs * is added to the rotational speed ωm detected by the speed detector 10 to obtain the primary angular frequency command ω ₁
It is output as *. Further, the non-interference controller 17 is configured to compensate for the interference term by using the current components I ₁ d *, I ₁ q * and the primary angular frequency command ω ₁ *.

In the vector controller having the above construction, for example, when the slip angular frequency controller 16 obtains the slip angular frequency command ωs *, the following equation (23) is used.

[0078]

[Equation 23]

When using the equation (23), T2 measured by the above-mentioned method is used. When setting such a calculation constant, the control constant calculator 8 calculates the control constant based on the electric motor constant measured by the above-described method, and the constant of the calculation program of the vector controller 9 is set. It is possible. In addition, the current controller 14,1
5. Similarly, in the non-interference controller 17, the arithmetic constant can be set based on the measured electric motor constant.

[0080]

As described above, according to the present invention,
When a measurement signal is applied to an AC motor, a measurement signal in which a single-phase AC current flows through the AC motor is used.Therefore, the constant of the motor can be measured while the rotation of the motor is stopped. It can be measured with accuracy. Moreover, since the signal in which the DC bias is superimposed on the AC signal is used as the measurement signal, the motor constant can be measured with high accuracy without being affected by the voltage distortion due to the on-delay of the power converter.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a motor constant measuring device showing an embodiment of the present invention.

FIG. 2 is a diagram showing a block diagram model of an electric motor.

FIG. 3 is a diagram showing a block diagram model of an electric motor during measurement.

FIG. 4 is a voltage waveform diagram during measurement.

FIG. 5 is a circuit configuration diagram of a vector controller for an induction motor.

[Explanation of symbols]

 1 AC motor 2 PWM inverter 3 Coordinate converter 4a, 4b Current detector 5 Coordinate converter 7 Motor constant calculator 8 Control constant calculator 9 Vector controller

Claims (9)

[Claims] 1. A three-phase voltage command signal is generated in accordance with a d-axis voltage command, a q-axis voltage command, and a primary angular frequency command, and the output voltage of the power converter is controlled in proportion to this and applied to the electric motor. When detecting the output current of the inverter and detecting the d-axis current component and the q-axis current component according to the detected current and the primary angular frequency command, each of the command values of the primary angular frequency command and the q-axis voltage command is set to zero. An AC signal is given as a command value of the d-axis voltage command below, and a converter output voltage according to a three-phase voltage command signal generated based on this is applied to the electric motor, and at this time, a d-axis current component flowing in the electric motor is detected. Then, the electric motor constant measuring method is characterized in that the electric motor constant is obtained based on the detected value. 2. A three-phase voltage command signal is generated according to a d-axis voltage command, a q-axis voltage command, and a primary angular frequency command, and the output voltage of the power converter is proportionally controlled and applied to the electric motor. When detecting the output current of the inverter and detecting the d-axis current component and the q-axis current component according to the detected current and the primary angular frequency command, each of the command values of the primary angular frequency command and the d-axis voltage command is set to zero. Below, an AC signal is given as the command value of the q-axis voltage command, the converter output voltage according to the three-phase voltage command signal generated based on this is applied to the motor, and the q-axis current component flowing in the motor is detected at this time. Then, the electric motor constant measuring method is characterized in that the electric motor constant is obtained based on the detected value. 3. A three-phase voltage command signal is generated in accordance with the d-axis voltage command, the q-axis voltage command, and the primary angular frequency command, and the output voltage of the power converter is controlled in proportion to this and applied to the electric motor. When detecting the output current of the inverter and detecting the d-axis current component and the q-axis current component according to the detected current and the primary angular frequency command, each of the command values of the primary angular frequency command and the q-axis voltage command is set to zero. An AC signal is given as a command value of the d-axis voltage command below, and a converter output voltage according to a three-phase voltage command signal generated based on this is applied to the electric motor, and at this time, a d-axis current component flowing in the electric motor is detected. Then, the detected value is analyzed according to the Fourier expansion by a trigonometric function with the AC signal as a reference, and the constant of the electric motor is obtained based on the Fourier coefficient of the fundamental wave component and the AC signal value. Motor constant measurement method characterized. 4. A three-phase voltage command signal is generated in accordance with a d-axis voltage command, a q-axis voltage command, and a primary angular frequency command, and the output voltage of the power converter is controlled in proportion to this and applied to the electric motor. When detecting the output current of the inverter and detecting the d-axis current component and the q-axis current component according to the detected current and the primary angular frequency command, each of the command values of the primary angular frequency command and the d-axis voltage command is set to zero. Below, an AC signal is given as the command value of the q-axis voltage command, the converter output voltage according to the three-phase voltage command signal generated based on this is applied to the motor, and the q-axis current component flowing in the motor is detected at this time. Then, the detected value is analyzed according to the Fourier expansion by a trigonometric function with the AC signal as a reference, and the constant of the electric motor is obtained based on the Fourier coefficient of the fundamental wave component and the AC signal value. Motor constant measurement method characterized. 5. The method of measuring a motor constant according to claim 1, wherein a signal obtained by superimposing a DC bias on an AC signal is used as a command value of the voltage command. 6. A d-axis based on a q-axis current command, an exciting current command, a q-axis current component, and a d-axis current component, based on the electric motor constant obtained by the measuring method according to any one of claims 1 to 5. A control constant setting method for a vector controller, comprising setting a control constant of a vector controller for generating an axial voltage command, a q-axis voltage command, and a primary angular frequency command. 7. A three-phase voltage command signal generating means for generating a three-phase voltage command signal according to a d-axis voltage command, a q-axis voltage command and a primary angular frequency command, and an AC voltage proportional to the three-phase voltage command to the electric motor. A power converter to be applied, an output current detecting means for detecting an output current of the power converter, a current component for generating a d-axis current component and a q-axis current component according to the detected current of the output current detecting means and the primary angular frequency command. Generating means, measuring signal generating means for setting the respective command values of the primary angular frequency command and the q-axis voltage command to zero, and giving an AC signal as the command value of the d-axis voltage command, and three-phase changing in accordance with the AC signal And a motor constant calculating means for calculating a constant of the motor based on the d-axis current component detected by the current component generating means as a result of the application of the AC voltage to the motor. Stationary device. 8. A three-phase voltage command signal generating means for generating a three-phase voltage command signal in accordance with a d-axis voltage command, a q-axis voltage command and a primary angular frequency command, and an AC voltage proportional to the three-phase voltage command to the electric motor. A power converter to be applied, an output current detecting means for detecting an output current of the power converter, a current component for generating a d-axis current component and a q-axis current component according to the detected current of the output current detecting means and the primary angular frequency command. Generating means, measuring signal generating means for setting the respective command values of the primary angular frequency command and the d-axis voltage command to zero and giving an alternating current signal as the command value of the q-axis voltage command, and three-phase varying according to the alternating signal An electric motor constant measuring means for calculating a constant of the electric motor based on the q-axis current component detected by the electric current component generating means as a result of the application of the AC voltage to the electric motor. Stationary device. 9. The motor constant measuring device according to claim 7, wherein the measurement signal generating means generates a signal in which a DC bias is superimposed on an AC signal as a command value of the voltage command.