JP2646949B2 - Torque electric operation method AC electric dynamometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC electric dynamometer for obtaining torque of an engine or the like by a torque electric operation method.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a block diagram showing a conventional torque electric operation type AC electric dynamometer disclosed in Japanese Unexamined Patent Application Publication No. H10-115,004. In the figure, 1 is a three-phase AC power supply, and 2 is a power converter, which supplies the induction machine 3 with three-phase AC power having a variable frequency and a variable voltage. 4 is a current detector, 5 is a voltage detector, 6 is a rotation speed detector, 7 is an induction machine 3
And a power detection converter 8 for detecting or calculating a motor current I, a voltage V, a rotation speed N, a motor internal temperature t, and a motor input Pin, respectively.
Enter

Next, the operation will be described. The torque calculation device 9 detects the motor input in consideration of the output torque obtained by dividing the motor output by the rotation speed, and subtracts each loss of copper loss, iron loss, mechanical loss, and stray load loss therefrom. Is a device for calculating the output shaft torque T [kg · m] of the motor by calculating the motor output and dividing the output by the number of revolutions, and executes the following equation (1).

[0004] T = I / N · (Pin -AI 2 -BV-CV 2 -DN 3/2 -E) ... (1)

[0005] AI ² is copper loss, BV and CV ² are hysteresis loss and eddy current loss, both iron loss, DN ^3/2 is mechanical loss, and E is stray load loss.

In the equation (1), each of the constants A, B, C, D and E is obtained by actually measuring the shaft torque at at least five arbitrary points by simulation operation in advance.
It is determined by substituting into equation (1) and solving five simultaneous equations. However, each loss of the induction machine changes depending on the internal temperature, and the constants A, B, C, and D of the above losses are functions of the temperature. For this reason, the constants A, B, C, and D are obtained by changing the internal temperature of the induction machine, and stored as a table of temperature-constant characteristics. That is, to detect the internal temperature t, parameters A, B, C, and D that match the measured temperature are selected from the table, or if there are no parameters, linear interpolation is performed to determine the optimal parameters. That's why.

[0007]

A conventional torque electric operation type AC electric dynamometer is constructed as described above. Since the electric power is measured on the three-phase AC side, an expensive power detection converter 8 is required. In addition, since the response of the power detection converter 8 is generally slow, there is a problem that it is difficult to respond when high-speed control is required.

Further, in the conventional torque electric calculation type AC electric dynamometer, the torque is corrected using a table of the temperature-constant characteristic. There is a problem that it is necessary to build the table before shipping, which requires a great deal of labor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to detect a motor input without using an expensive power detection converter, and to increase the response speed as compared with the prior art. And It is another object of the present invention to enable correction without a table of temperature-constant characteristics, and to save labor for test adjustment before shipping.

[0010]

SUMMARY OF THE INVENTION An AC electric dynamometer of the torque electric operation type according to the present invention is controlled by means for detecting current and voltage on the DC side of a power converter and an inverter which is a part of the power converter. Field current (hereinafter referred to as d-axis current Id) and torque current (hereinafter referred to as q-axis current Id).
q), means for detecting the temperature inside the induction machine, means for detecting the number of revolutions of the induction machine, torque for calculating the torque based on these detection signals, and performing temperature correction. It is provided with an arithmetic unit.

[0011]

The torque electric operation type AC electric dynamometer according to the present invention comprises a current I and a voltage V on the DC side of a power converter, a d-axis current Id controlled by an inverter which is a part of the power converter, and The q-axis current Iq, the temperature t inside the induction machine, and the rotation speed N of the induction machine are detected, the torque is calculated based on these detection signals, and the temperature is corrected. For this reason, the expensive power detection converter which was indispensable conventionally becomes unnecessary.

[0012]

【Example】

Embodiment 1 FIG. Hereinafter, a first embodiment of the present invention will be described with reference to FIG. In FIG. 1, 1 is a three-phase AC power supply, and 2 is a power converter. The power conversion device 2 includes a converter 2a that converts AC into DC, and an inverter 2b that converts DC power output from the converter 2a into AC and supplies the induction machine 3 with three-phase AC power of variable frequency and variable voltage.
It is composed of

4 is a DC current detector for detecting a DC current output from the converter 2a, 5 is a DC voltage detector for detecting a DC voltage output from the converter 2a, 6 is a rotational speed detector, and 7 is an induction motor. The current I, the voltage V, the number of revolutions N, and the internal temperature t of the electric motor are detected by the temperature detectors 3 and input to the torque calculation device 9. Inverter 2
In b, means for detecting the q-axis current Iq and the d-axis current Id are provided, and the q-axis current signal 10 and the d-axis current signal 1 are provided.
1 is input to the torque calculation device 9.

Next, the operation will be described. For DC,
Since the power is represented by the scalar product of the DC voltage V and the DC current I, if the loss of the power converter 2 can be ignored, the motor input is represented by the scalar product of the DC voltage V and the DC current I. . Therefore, if the DC voltage V and the DC current I are measured, the motor input can be obtained only by integrating these values.
It can be obtained more than twice as fast.

The output torque is obtained by dividing the output of the motor by the number of revolutions. Therefore, the torque calculation device 9
It is a device that calculates the motor output by subtracting each loss of copper loss and stray load loss from the motor input, divides this by the number of rotations, and calculates the motor output shaft torque T [kgm]. Execute equation (2).

T = K / N · [IV−K1 · α · r1 · (Id ² + Iq ² ) −K2 · α · r2 · Iq ² −E] (2)

Now, in equation (2), K1 · α · r1 · (I
d ² + Iq ² ) represents the primary copper loss of the induction machine 3, K2 · α · r2 · Iq ² represents the secondary copper loss of the induction machine 3, and E represents the stray load loss.
α is a temperature correction coefficient of the resistance, which is a function of the induction machine internal temperature t measured by the temperature detector 7, and performs the temperature correction of the primary resistance r1 and the secondary resistance r2 of the induction machine 3. K, K1, and K2 are coefficients.

Embodiment 2 FIG. In the first embodiment, when the DC voltage V and the DC current I are detected, the DC voltage detector 5 and the DC current detector 4 are provided on the output side of the converter 2a. Is controlled by the converter 2a, the DC voltage signal and the DC current signal detected for control by the converter 2a may be used as they are, and may be taken into the torque calculation device 9.

Embodiment 3 FIG. FIG. 2 shows a third embodiment of the present invention.
Shown in In the first embodiment, only the copper loss and the stray loss are corrected. However, if the no-load loss correction unit 12 is added as shown in FIG. 2 and the following equation (3) is executed, The torque calculation accuracy can be improved. The contents will be described based on equation (3).

T = K / N · [IV−K1 · α · r1 · (Id ² + Iq ² ) −K2 · α · r2 · Iq ² -E] -Tm (3)

The mechanical loss and the iron loss are almost constant irrespective of the load. Therefore, the sum of the mechanical loss and the iron loss can be expressed as a no-load loss, and is a function of the rotational speed N. That is, the torque obtained by operating the induction machine 3 with no load and executing the equation (2) is the no-load loss Tm. Therefore, when the induction machine is operated with no load in the adjustment operation, the equation (2) is executed and the torque obtained for each rotation speed is stored as a no-load correction table, and the rotation speed measured in the actual operation is stored. By providing the load loss correction unit 12 that reads the no-load loss Tm corresponding to N from the no-load correction table and corrects it, and by executing the equation (3), the torque calculation accuracy is improved.

Embodiment 4 FIG. FIG. 3 shows a fourth embodiment of the present invention.
Shown in In the third embodiment, the no-load loss correction unit 12 is provided to correct the mechanical loss and the iron loss. However, as shown in FIG.
And the load loss σ centering on the loss of the power converter 2
If T is corrected, the accuracy of torque calculation can be further improved. The contents will be described based on the following equation (4).

T = K / N · [IV−K1 · α · r1 · (Id ² + Iq ² ) −K2 · α · r2 · Iq ² -E] -Tm-σT (4)

In the pre-shipment adjustment operation, a load operation is performed by providing a means such as a shaft torque meter for detecting the shaft torque of the induction machine, and the shaft torque detected from the shaft torque meter and the equation (3) are executed. When an error from the calculated torque obtained by the calculation is obtained, it is the load loss σT.

Therefore, in the adjustment operation, the induction machine 3
(3) is executed when a load is applied to the motor, and the rotational speed and the torque obtained for each load are provided as a torque error correction table, and the rotational speed N measured in the actual operation and (3) A torque error correction unit 13 that reads a torque error σT corresponding to a calculation torque obtained by executing the equation from the torque error correction table and corrects the torque error;
By executing the equation (4), further improvement in torque calculation accuracy is realized.

Embodiment 5 FIG. In the fourth embodiment, the stray load loss E and the load loss σT are separated, but the same applies even if the correction of the stray load loss E is consolidated into the load loss σT as shown in the following equation (5). The effect can be obtained.

T = K / N · [IV−K1 · α · r1 · (Id ² + Iq ² ) −K2 · α · r2 · Iq ² ] −Tm−σT (5)

Embodiment 6 FIG. In the fourth embodiment, the no-load loss correction unit 12 and the torque error correction unit 13 are separated. However, since the no-load loss Tm can be regarded as a part of the load loss σT, the following expression (6) is used. As shown in FIG.
The same effect can be obtained even when the functions of the second method are integrated in the torque error correction unit 13.

T = K / N · [IV−K1 · α · r1 · (Id ² + Iq ² ) −K2 · α · r2 · Iq ² -E] −σT (6)

[0030]

As described above, according to the present invention, the current and voltage on the DC side of the power converter, the current for the d-axis and the current for the q-axis controlled by the inverter which is a part of the power converter. Since the rotational speed and the temperature of the induction machine are detected and the shaft torque is calculated using these detection signals, an expensive power conversion detector, which has been indispensable in the past, becomes unnecessary, and the apparatus is configured at low cost. be able to. In addition, since the response speed can be increased as compared with the related art, it can be applied to applications that require high-speed control.

Further, since the temperature inside the induction machine is detected and the temperature is corrected by the temperature correction coefficient of the resistance which is a function of the temperature inside the induction machine, the table of the temperature-constant characteristic becomes unnecessary, and the table before shipping is not required. Test adjustment is labor-saving.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a third embodiment of the present invention.

FIG. 3 is a block diagram showing a fourth embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional torque electric operation type AC electric dynamometer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Power converter 2a Converter 2b Inverter 3 Induction machine 4 DC current detector 5 DC voltage detector 6 Speed detector 7 Temperature detector 9 Torque calculation device 10 q-axis current 11 d-axis current 12 No-load loss Correction unit 13 Torque error correction unit

Claims (3)

(57) [Claims] 1. A current I and a voltage V on a DC side of a power converter.
And d controlled by an inverter which is a part of the power converter.
Means for detecting the shaft current Id and the q-axis current Iq; means for detecting the temperature t inside the induction machine; means for detecting the rotation speed N of the induction machine; and a torque calculation unit for performing the temperature correction to calculate the torque calculation unit, T = K / N · [ IV-K1 · α · r1 · (Id 2 + Iq 2) -K2 · α · r2 · Iq 2 -E], wherein the shaft torque T is calculated based on the following equation. 2. The torque electric operation type AC electric dynamometer according to claim 1, further comprising: a no-load loss correction unit including a rotation speed-no-load loss correction table for giving a no-load loss Tm at each rotation speed; The arithmetic device calculates the shaft torque T based on T = K / N · [IV−K1 · α · r1 · (Id ² + Iq ² ) −K2 · α · r2 · Iq ² -E] −Tm An AC electric dynamometer characterized by a torque electric operation method. 3. The torque calculator according to claim 2, further comprising: a torque error corrector provided with a load loss correction table for providing a load loss σT using the rotation speed and the torque as parameters. is for calculating the axial torque T based on T = K / N · [IV -K1 · α · r1 · (Id 2 + Iq 2) -K2 · α · r2 · Iq 2 -E] -Tm-σT An AC electric dynamometer characterized by a torque electric operation method.