JP3265768B2 - Variable speed device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable speed device for an induction motor, and more particularly to a variable speed device having a current control system and having a function of measuring the constant of an induction motor for vector control.

[0002]

2. Description of the Related Art As a method of measuring the constant of an induction motor, JE
There are standards such as C37. In JEC37, the primary resistance is measured by a DC potential drop method, the leakage inductance and the secondary resistance are measured by a constraint test, and the excitation inductance is measured by a no-load test.

[0003]

In the conventional constant measuring method, means for fixing the output shaft of the motor is required for the constraint test, and a large-scale instrument is often required for the measurement.

[0004] Further, as for the measurement conditions, since the measured voltage is low, the desired voltage accuracy is obtained by measuring at a frequency higher than the frequency component generated in the secondary circuit during the actual operation.

[0005] For this reason, in the restraint test of an induction motor in which the secondary conductor has a special shape such as a double cage, a leakage inductance value measured at a frequency higher than the operating frequency and an actual operating time are reduced due to the skin effect. An error occurs between this value and

Therefore, when vector control using a measurement constant obtained by a constraint test such as JEC37 or high-function control such as temperature fluctuation compensation of a secondary resistor in vector control is performed, an error occurs in output torque and the like. High precision control becomes difficult.

As described above, in the conventional constant measurement, the induction machine constant under the actual operating condition cannot be accurately obtained.
In the vector control, a load torque characteristic test was actually performed, and the induction machine constant was adjusted according to the operator's feeling so that the torque characteristic results and the operating characteristics such as the transient response characteristics matched the ideal characteristics.

The present inventors have already proposed a method for measuring the constant of an induction machine with high accuracy using a transient phenomenon (1993 National Convention of the Institute of Electrical Engineers of Japan, Proceedings [6], 22).
P. 636, induction machine constant measurement using an inverter).

In this measurement method, there is a measurement condition of no-load operation, but in an actual variable speed facility, complete no-load operation cannot be performed after the induction machine is installed in a gear device or the like. There may be some load torque and measurement under no-load operating conditions may not be possible.

[0010] It is an object of the present invention to provide a variable speed device that can measure a motor constant with high accuracy even when a load is connected to an induction motor, and that facilitates constant measurement.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has a current control system for controlling a current supplied from a semiconductor power converter to an induction machine, and a variable speed control system for controlling the induction machine. A first measuring means for measuring and storing a primary voltage, a current, and a frequency component of an induction machine in a steady operation state, and an induction after a current command of the current control system is suddenly changed to zero in the steady operation state; Second measuring means for measuring and storing the primary voltage, current and frequency components of the machine at different times, and the attenuation coefficient of the measured voltage value after suddenly changing the current command to zero among the measured and stored data of the two measuring means. Calculates the secondary time constant τ ₂ of the induction machine from, and calculates the magnetic flux phase error Δφ between the actual magnetic flux axis and the control axis from the secondary time constant τ ₂ and the voltage and frequency components before and immediately after the change of the current zero. A variable speed device comprising an arithmetic unit .

Further, according to the present invention, the arithmetic unit approximates the primary voltage measurement value after the current command is rapidly changed to zero by an exponential function, and changes the current command to zero from a coefficient component of the approximate expression. Voltage initial value estimating means for estimating the output voltage component immediately after, the speed electromotive force component calculating means for separating and calculating the speed electromotive force component of the estimated voltage component, and the magnetic flux from the current component in the steady operation state. A magnetic flux axis current component calculating means for extracting an exciting current component corresponding to the actual magnetic flux axis by a phase error; and an exciting inductance based on the speed electromotive force, the magnetic flux axis current component and the angular velocity when the current command is suddenly changed to zero by each of the calculating means. A calculating means for calculating M ′; a voltage component orthogonal to the current among the voltage difference between the voltage measurement value during the steady operation and the speed electromotive force; the current value during the steady operation; Calculating means for calculating the distance Lσ.

[0013]

The principle of measuring the constant of an induction machine using the variable speed device of the present invention will be described below.

(1) Approximation of Equivalent Circuit In vector control, for simplicity, the iron loss component is expressed by T-I
Treated as an iron loss resistance in parallel with the exciting inductance M 'of the type equivalent circuit. This is an approximation that the iron loss current circuit and the secondary circuit are tightly coupled by the exciting inductance M ′ and that there is no leakage component.

For simplicity of control, this approximation condition is also applied to an equivalent circuit on two axes, and the dq axis circuit is separated and T
As shown in FIG. 2 representing an -I type equivalent circuit, the resistance is treated as a parallel resistance of a secondary resistance R ₂ ′ and an iron loss resistance R _m ′.

(2) Basic circuit equation In the equivalent circuit of FIG. 2, the voltage / current equation on the biaxial coordinates synchronized with the power supply frequency ω1 can be expressed by the following equation (1).

[0017]

(Equation 1)

V _1d , V _1q : d, q-axis primary voltage i _1d , i _1q : d, q-axis primary current λ _2d , λ _2q : d, q-axis secondary flux linkage ω ₁ : primary angular frequency ω _S : Slip angular frequency R ₁ : Primary resistance R ₂ : Secondary resistance of TI equivalent circuit Lσ: Primary leakage inductance of TI equivalent circuit M ′: Primary excitation inductance of TI equivalent circuit R _m ′: T− I-type equivalent circuit core loss resistance M: magnetizing inductance of T-type equivalent circuit P: differential operator R _2m ′ = 1 / (1 / R ₂ ′ + 1 / R _m ′) λ ₂ / M = i ₁ − (i ₂ '+ IRM') (3) State during steady-state operation A vector-controlled variable speed device having a current control system supplies an AC voltage from a semiconductor power converter such as a voltage-type inverter to an induction motor during steady-state operation. The current is controlled by a current control system that performs vector control calculation. The current command to the current control system includes a torque current I _1q and an excitation current I _1d
And give.

In a steady operation at an arbitrary speed and a load torque, the current components on the d-axis and the q-axis are expressed by the following equation (2). There is an iron loss current component. Each component is given a () _-0 symbol as in a normal operation.

[0020]

(I _1d ) ₋₀ = (λ _2d / M) ₋₀ , (λ _2q / M) ₋₀ = 0 (i _1q ) ₋₀ = (i _2q ′) ₋₀ + (iRM _q ′) _-0 (2) (i _1d ) _-0 : Primary d-axis current component at steady state (i _1q ) _-0 : Primary q-axis current component at steady state (λ _2d / M) _-0 , (λ _2q / M) _-0 : d and q-axis components obtained by dividing the secondary flux linkage by M (i _2q ') _-0 : Secondary torque current component (iRM _q ') _-0 : Secondary iron loss current component When applied to the equivalent circuit of FIG. 2, the result is as shown in FIG. The actual magnetic flux axis is the d-axis, and the magnetic flux component in the steady operation state is as follows: (a) a magnetic flux component (λ _2d /
M) _-0 (b) Leakage flux component L that does not interlink secondarily due to excitation current
σ · (i _1d ) ₋₀ (c) There are three types of leakage magnetic flux components Lσ · (i _1q ) _{−0 that} do not have secondary linkage due to torque current. (Λ _2q / M) _-0 is zero.

Here, the voltage and current components during the steady operation are represented by a space vector diagram as shown in FIG.

(3) State immediately after the sudden change of current zero When the current command to the current control system is suddenly changed to zero from the steady operation state, the response of the current control system is sufficiently fast, and the output voltage capacity of the current control system is reduced. If it is large enough, the primary current also instantaneously changes to zero. At this time, the magnetic energy of the leakage magnetic flux of the d and q axes components linked to the leakage inductance Lσ is also absorbed by the power supply and becomes zero.

However, since the secondary flux linkage component of the d-axis does not link with the primary circuit even when the primary current becomes zero, the secondary flux linkage component attempts to maintain the flux component. Therefore, when the d-axis primary current (i _1d ) _-0 component becomes zero, the current is commutated to the d-axis secondary circuit. Each component is given the symbol () _{+0 as in the case of} zero current operation.

[0024]

(3) (λ _2d / M) ₊₀ = − (i _2d ′) ₊₀ = (i _1d ) ₋₀ (3) FIG. 5 shows the state immediately after the sudden change of the current. The space vector is shown in FIG.

As described above, since the primary current is zero when the current suddenly changes to zero, the above-mentioned secondary flux linkage is the only magnetic flux component. The current component includes an exciting current component (i _2d ′) ₊₀ and a core loss current component (iRM _q ′) _{+0, which} are secondary commutated. Here, the iron loss current component is sufficiently smaller than the exciting current component and can be ignored.

(4) Transient Phenomena after Rapid Change of Current Zero It is assumed that the primary current is maintained to be rapidly changed to zero, and the d and q control axes are rotating in synchronization with the rotor of the induction machine. At this time, the primary current is maintained at zero, and the secondary circuit is not affected by the primary current.

For this reason, the secondary magnetic flux component and the secondary current component on the coordinates synchronized with the rotor have a simple condition in which energy is consumed by the secondary resistor R ₂ ′ with the condition of the equation (3) as an initial value. Changes as a DC transient.

Therefore, the secondary flux linkage is an exponentially attenuating equation such as the following equation (4).

[0029]

Λ _2d / M (t) = (λ _2d / M) ₋₀ · exp (−1 / τ ₂ · t) λ _2d / M (t) = 0 (4) τ ₂ : quadratic Time constant (= M ′ / R ₂ ′) The voltage generated in the primary circuit by the secondary magnetic flux is represented by a d-axis voltage component (transformer electromotive force due to a change in the magnetic flux component itself) and q
There is an axial voltage component (speed electromotive force due to relative motion between the magnetic flux on the rotor and the stator), and each is given by the following equation (5).

[0030]

V _1d (t) = p {λ _2d / M) _{+ 0} · exp (−1 / τ ₂ · t)} = − 1 / τ ₂ · M ′ · (λ _2d / M) _{+ 0} · exp (−1 / τ ₂ · t) (5-1) V _1q (t) = ω ₁ (t) · M ′ · (λ _2d / M) _{+ 0} · exp (−1 / τ ₂ · t) FIG. 7 shows d * and q * of the control axis of the output voltage of the current control system when the current is suddenly changed to zero using the variable speed system.
4 shows a measured waveform of an axis component.

As is apparent from the measured waveforms, the exponential function voltages of the above equations (5-1) and (5-2) are generated on each axis. These d * and q * axis voltage components are measured and stored for about the second order time constant.

(5) Calculation of induction machine constant (5a) Estimation of secondary time constant and voltage value immediately after sudden change of current by approximation of exponential function It should be noted here that actual magnetic flux axes d and q and the inside of control system The assumed magnetic flux axis d * does not always match. Actually, as shown in FIGS. 4 and 6, there may be an axis deviation Δφ between these axes. Therefore, the control axis is defined by the symbols d * and q *, and the measurement is performed using these d * and q *.
Perform on the axis.

From the measured data at the time of the sudden change to zero current, the measured values of the d * and q * -axis voltages at the time of the transition are approximated by an exponential function of the following equation (6) to _obtain (V _1d *) ₊₀ , (V _1q *) From the coefficients of ₊₀ and _τ2q *, find the initial value and the secondary time constant immediately after the current suddenly changes to zero.

[0034]

V _1d * (t) = (V _1d *) _{+ 0} · exp (−1 / τ _2d * · t) V _1q * (t) = (V _1q *) _{+ 0} · exp (−1 / τ _2q * · t) (6) Here, the q-axis component (speed electromotive force) is usually used instead of the d-axis component.
Is larger in measurement voltage, and the second order time constant τ ₂ ≒ τ _2q * is used from the viewpoint of measurement accuracy. Also, (V _1d *) ₊₀
And (V _1q *) ₊₀ can be regarded as an approximate value of the initial value of the transient phenomenon at the time of a sudden change in current.

(5b) Calculate the axis shift phase between the control axis and the actual magnetic flux axis. In the above equation (6), when approximating the rotation speed (ω _r = ω ₁ ) ≒ constant, (5-1), (5- From the relation of 2), d *,
The ratio of the q * -axis voltage components is constant as in the following equation.

[0036]

(V _1d *) _{+ 0} / (V _1q *) _{+ 0} = (− 1 / τ ₂ ) / ω ₁ ≒ Constant For this reason, if the attenuation of the rotational speed is small, the voltage of each axis can be obtained at any time. The ratio will be constant. FIG. 8 shows this in an actual example. The figure shows the voltage component of each axis measured in FIG.
This is converted on the plane coordinates of the * and q * axes.

When the current suddenly changes to zero, the voltage component changes suddenly, but thereafter, the voltage vector moves on a straight line of the following equation (7) passing through the origin with the passage of time.

[0038]

V _1q (t) = (− τ ₂ · ω ₁ ) V _1d (t) (7) In other words, the measured voltage is the speed electromotive force V on the q-axis.
The combined V ₁ of _1q and the component of the d-axis transformer electromotive force V _1d is represented by d
The measurement is based on the control axes * and q *.

Here, the q-axis phase orthogonal to the actual magnetic flux axis is rotated by the following equation (8) from the phase of the measured voltage vector (V ₁ ) _{+0 according to} the equation (7). It can be seen that it exists in the phase.

[0040]

Θ _a = tan ⁻¹ (τ ₂ ′ · ω ₁ ) (8) The phase of the actual magnetic flux on the control axis is

[0041]

(Φ _V *) _{+ 0} = tan ⁻¹ {(V _1q *) _{+ 0} / (V _1d *) _{+ 0} } Δφ = (φ _V *) _{+ 0−} θ _a −90 ° 9) Here, ω ₁ is known from the operating conditions, and τ ₂ can use the coefficient of the approximate expression of the above equation (6), and the axis deviation angle Δφ can be calculated from the measurement and calculation results up to now. is there.

(5c) Calculation of Excitation Inductance M 'and Leakage Reactance Lσ Once the axis shift phase component Δφ is determined, the excitation inductance M' is equal to the amplitude component of the speed electromotive force component (V _1q ) _{+ 0} = E ₂ and orthogonal to it. From the exciting current component to be calculated.

The speed electromotive force component is

[0044]

| E ₂ | = ｛(V _1d *) _{+ 0} ² + (V _1q *) _{+ 0} ² ｝ ^1/2 · cos (θ _a ), and the exciting current component is

[0045]

(I ₀ ) _{+ 0} = | (i ₁ ) ₋₀ | · cos (φ _i −Δφ)} From these, the excitation inductance M ′ is obtained from the following equation.

[0046]

M ′ = | E ₂ | / {ω ₁ · | (i ₁ ) ₋₀ | · cos (φ _i −Δφ)} (10) The leakage reactance Lσ is also the voltage (V ₁ ) during steady operation. ) _-0 and orthogonal component with respect to the current of the differential voltage between E ₂ ([delta] axes)
And the current component during steady operation can be obtained from the following equation (11).

[0047]

ΔV ₁ δ = | (V ₁ ) ₋₀ | · sin ｛(φ _V *) _-0 − (φ _i *) ₋₀ ｝ − | E2 | · sin ｛(φ _V *) ₊₀ − (Φ _i *) _-0 −θ _a ｝ Lσ = ΔV ₁ δ / ｛ω ₁ · | (i ₁ ) _-0 |｝ (11) (5d) Excitation inductance M ′ and leakage reactance under no load condition Calculation of Lσ With no load, axis deviation can be ignored.

[0048]

(I ₁ ) ₋₀ ≒ (I _1d *) ₋₀ , θ _a ≒ 0, | E ₂ | ≒ (V _1q *) ₊₀ , ΔVδ ≒ (V _1q *) ₋₀ − (V _1q *) ₊₀ holds, and the following simplified expression is obtained.

[0049]

M ′ = (V _1q *) _{+ 0} / ｛ω ₁ · (I _1d *) ₋₀ Ｌ Lσ = ｛(V _1q *) ₋₀ − (V _1q *) ₊₀ ｝ / ｛ω ₁・ (I _1d *) ₋₀ … (12) From the above, according to the present invention, the induction in which the load torque exists is obtained from the current / voltage measurement value at the time of steady operation and the current / voltage measurement value at the time of a sudden change in current zero. Obtain the machine constants by calculation.

[0050]

FIG. 1 is a block diagram showing one embodiment of the present invention. The induction motor 1 is supplied with an AC voltage having a PWM waveform subjected to vector control from the semiconductor power converter 2. The rotor speed ω _r of the induction motor 1 is detected by the speed detector 3. The primary current of the induction motor 1 is separated into a torque current component and an exciting current component by a current detector 4 and detected.

The current control systems 5 and 6 provide an excitation current command i _1d *
Then, the excitation voltage control signal V _1d and the torque voltage control signal V _1q are supplied to the semiconductor power conversion device 2 so that the current is generated according to the command current by comparing the torque current command i _1q * with the detected current components.

[0052] excitation current calculation unit 7 receives the speed detection signal omega _r, and outputs the excitation current command (or excitation flux) i _1d. The torque current calculation unit 8 obtains a torque current component orthogonal to the magnetic flux axis from the torque command from the speed control system and the excitation current command, and outputs a torque current command i _1q .

The slip frequency calculator 9 calculates the excitation current command i
_The slip frequency ω _s is obtained from _1d and the torque current command i _1q . Frequency and phase calculation unit 10, together determine the frequency of the AC voltage supplied to the induction motor 1 by adding the slip frequency omega _s and the rotor speed detection value omega _r, determine the phase θ of the magnetic flux axis by integrating its frequency .

In the present embodiment, the calculation / measurement elements 11 to 15 are provided as the constant measuring means of the induction motor 1 in the vector-controlled variable speed device having the above configuration.

The switch 11 _supplies the current commands i _1d * and i _1q * from the excitation current calculation unit 7 and the torque current calculation unit 8 to the current control systems 5 and 6 in the steady operation state. _1d * and _i1q * are suddenly changed to zero.

The measurement / storage unit 12 detects the output current detection values i _1d , i _1q (or the current commands i _1d *, i _1q *) in the steady state before the changeover switch 11 suddenly changes the current command to zero.
And the voltage control signals V _1d and V _1q (or the voltage applied to the induction motor 1) and the angular frequency ω ₁ are measured and stored.

The measurement / storage unit 13 stores the output current detection values i _1d , i _1q (or the current commands i _1d *, i _1q *) in the transient state after the switching in which the changeover switch 11 suddenly changes the current command to zero.
And changes in the voltage control signals V _1d and V _1q (or the voltage applied to the induction motor 1) and the angular frequency ω ₁ are measured and stored for each time.

The measurement command unit 14 receives a data acquisition command to the measurement / storage unit 12 in a steady operation state when measuring a constant,
A command to acquire data to the measurement / storage unit 13 at the same time as the changeover of the changeover switch 11 is generated.

The constant calculation unit 15 includes the two measurement / calculation units 12,
13 reads the data measured and stored, and reads the induction motor 1
Are obtained by calculation. This calculation includes the calculation of the secondary time constant τ ₂ by the expression (6), the calculation of the magnetic flux phase error Δφ by the expression (9), the calculation of the excitation inductance M ′ by the expression (10), and the calculation of the (11) The calculation of the leakage reactance Lσ is performed by the equation (1).

As an experiment in this embodiment, the current control systems 5 and 6 are configured to perform PI control on rotational coordinates, and a 22 KW
The test induction motor of -6P, 325V-1180 rpm was operated at 1000 rpm to measure the constant.

[0061] Figure 7 is a no-load voltage V when the sudden change of the current to zero during operation _1d *, V _1q * indicates a waveform, 17 points samples (about tau _2/2 hours) to 20ms for each of the voltage waveform Then, each constant was obtained. As a result, the axis shift obtained by approximation by the above equation (8) was Δφ = 0.3 °, and the respective constants were calculated using the equation (12) under the condition of no axis shift. The results are shown in Table 1 below.

[0062]

[Table 1]

In order to verify the accuracy of the measurement result of the constant,
The torque characteristics were measured by applying to a vector-controlled variable speed device. This characteristic is shown in FIG. Here, the compensation value of the iron loss current is set to zero, and no correction is performed. Further, the measurement is performed up to the rated torque of 75% depending on the convenience of the load device, and the load region beyond that is extrapolated and indicated by a dotted line.

From this characteristic, when there is no compensation for the secondary resistance R ₂ , a torque error of about 10% occurs at the time of rating, and the secondary time constant τ ₂ is measured lower than that of the actual machine from the torque characteristic. It is estimated to be. This is believed to influence the secondary resistance R ₂ and the iron loss are present in parallel the resistance and some varying magnetic saturation.

However, when the secondary resistance compensation using the error voltage between the model and the output is added, the torque error is about 3%.
It was found that the measured values of the excitation inductance M ′ and the leakage reactance Lσ used in the model can obtain practically sufficient accuracy when the measured value is about 1000 rpm.

The secondary time constant itself changes depending on the temperature during operation. To actually maintain the torque accuracy during operation, feedback control such as secondary resistance compensation is applied.

In other words, the secondary time constant changes during operation, and the accuracy of the initial setting is not so required, and it is sufficient that the approximate value is set.

On the other hand, the components of M ′ and Lσ directly affect the accuracy of the secondary resistance compensation control. For this reason, when performing secondary resistance compensation or the like in order to maintain torque accuracy, an accurate induction machine constant is required.

The constant measurement according to the present invention does not become unstable even without secondary resistance compensation, and it can be said that the measured value of R ₂ ′ has sufficient accuracy that can be used as an initial set value.

Also, the components of M ′ and Lσ have higher torque accuracy than the torque characteristics when the secondary resistance compensation control is performed, and it has been found that the accuracy that can be practically used is obtained.

[0071]

As described above, according to the present invention, the variable speed device for controlling the induction machine is used to calculate the primary voltage, the current and the frequency component of the induction machine in the steady operation state from the measured values of the steady operation state. Since each constant of the induction machine is calculated from the primary voltage and current of the induction machine and the measured values of the frequency components when the current command of the current control system is suddenly changed to zero, the following effects are obtained.

(1) By suddenly changing the current command to zero, a secondary current is generated by utilizing a commutation phenomenon, whereby a reliable secondary current can be generated even at a high frequency. In addition, the speed electromotive force component is increased by the high frequency, and the voltage detection error is reduced, so that highly accurate constant measurement can be performed.

(2) Since the current command is set at zero and the output current is maintained at zero, a voltage equal to the induced electromotive force of the induction machine can be generated as the output of the current control system. This makes it possible to measure the output voltage of the current control system and obtain a measurement value equivalent to the terminal voltage of the induction machine. That is, an external measuring device such as a voltmeter is not required, and the measurement can be performed with the variable speed device alone.

(3) Since the attenuation phenomenon of the secondary circuit is used, the frequency component of the magnetic flux change can be considered to be about the secondary time constant. Therefore, the leakage reactance component Lσ
Can be measured under conditions close to the actual operating state, and the measurement accuracy can be improved.

(4) Since a constant measurement can be performed with high accuracy by providing a small measuring means in the variable speed device, (a) the constant can be measured for each induction machine having a variation in the manufacturing process, and the optimal operation can be performed. (B) It is unnecessary to make adjustments that have been performed manually in the past, and adjustment man-hours can be reduced. (C) Optimal constant setting can be performed even for an induction machine whose constant is unknown, such as an existing induction machine. (D) There is an effect that an abnormality determination of the induction machine or the like is performed by checking constant fluctuation by periodically performing constant measurement.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a TI equivalent circuit diagram of an induction machine in which d and q axis circuits are separated.

FIG. 3 is a diagram showing currents and magnetic fluxes of primary and secondary circuits in a steady operation state.

FIG. 4 is a voltage vector diagram of FIG. 3;

FIG. 5 is a diagram showing currents and magnetic fluxes of primary and secondary circuits when the current suddenly changes to zero.

6 is a voltage vector diagram of FIG.

FIG. 7 is a transient voltage waveform chart at the time of a sudden change in current zero.

FIG. 8 shows a locus of a voltage vector.

FIG. 9 is a torque characteristic diagram during vector control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Induction machine 2 ... Semiconductor power converter 5, 6 ... Current control system 7 ... Excitation current calculation part 8 ... Torque current calculation part 11 ... Changeover switch 12, 13 ... Measurement / storage part 14 ... Measurement command part 15 ... Constant calculation Department

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02P 5/408-5/412 H02P 7/628-7/632 H02P 21/00 H02M 7/42-7 / 98 G01R 27/00-27/32 G01R 31/327-31/36 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A variable speed device having a current control system for controlling a current supplied from a semiconductor power converter to an induction machine and controlling the induction machine, comprising: a primary voltage and a current of the induction machine in a steady operation state; First measuring means for measuring and storing a frequency component; and measuring and storing the primary voltage, current, and frequency component of the induction machine after the current command of the current control system is suddenly changed to zero in the steady-state operation state. The second time constant τ ₂ of the induction machine is calculated from the attenuation coefficient of the voltage measurement value after the current command is suddenly changed to zero, from the measurement / storage data of the second measurement means and the two measurement means. A variable speed device comprising: a calculation unit that calculates a magnetic flux phase error Δφ between an actual magnetic flux axis and a control axis from a voltage and a frequency component before and after a change in a next time constant τ ₂ and a current zero. 2. The arithmetic unit according to claim 1, wherein the primary voltage measurement value after the current command is rapidly changed to zero is approximated by an exponential function, and an output immediately after the current command is changed to zero from a coefficient component of the approximate expression. A voltage initial value estimating means for estimating a voltage component; a speed electromotive force component calculating means for separating and calculating a speed electromotive force component among the estimated voltage components; A magnetic flux axis current component calculating means for extracting an exciting current component corresponding to the magnetic flux axis; and calculating an exciting inductance M ′ from the speed electromotive force, the magnetic flux axis current component, and the angular velocity when the current command is suddenly changed to zero by each of the calculating means. Calculating means for calculating the leakage inductance Lσ from the voltage component orthogonal to the current, the current value during the steady operation, and the angular velocity among the difference voltage between the voltage measurement value during the steady operation and the speed electromotive force. Variable speed device according to claim 1, further comprising a calculating means for calculation for.