Induction machine control device

Abstract

To improve the accuracy of torque control of an induction machine and prevent the induction machine from rotating in the opposite direction to a command.SOLUTION: An induction machine control device 100 includes a speed calculation unit 106 that calculates the induction machine speed ωm and the calculated magnetic flux magnitude φ2v on the basis of a primary resistance set value R1S, a current i flowing through the induction machine 1, and a voltage command v, an excitation determination unit 101 that generates an excitation elapsed time tF until the ratio of the calculated magnetic flux magnitude φ2v to the magnetic flux command F2 reaches a predetermined value, and a primary resistance setting unit 102 that sets the primary resistance set value R1S on the basis of the excitation elapsed time tF.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an induction machine control device for controlling an induction machine.

Background Art

[0002] FIG. 2 is a diagram showing a configuration example of a conventional induction machine control device 10. As shown in FIG. 2, the conventional induction machine control device 10 includes a current detector 2, a power converter 3, a torque control unit 4, a current command generation unit 5, a speed calculation unit 6, a slip frequency command generation unit 7, and an adder 8.

[0003] The current detector 2 detects a current i flowing through the induction machine 1 and outputs the detection result to the torque control unit 4 and the speed calculation unit 6.

[0004] The speed calculation unit 6 receives the detection result of the current i by the current detector 2, a voltage command v for instructing the output voltage to the induction machine 1, and a primary resistance reference value R1N which is a reference value of the primary resistance of the induction machine 1. The speed calculation unit 6 calculates the induction machine speed ωm based on the primary resistance reference value R1N, the current i, and the voltage command v.

[0005] Specifically, the speed calculation unit 6 calculates the calculated magnetic flux φ2 by the following formula (1).

[0006]

Equation

[0007] Here, L2 is the secondary self-inductance of the induction machine 1, M is the mutual inductance of the induction machine 1, and Lek is the leakage inductance of the induction machine 1. The leakage inductance Lek is given by the following formula (2).

[0008]

Equation

[0009] Next, based on the current i and the calculated magnetic flux φ2, the speed calculation unit 6 calculates the induction machine speed ωm according to the following equations (3) to (5). In equation (3), FA and FB are the a-axis component and b-axis component of the calculated magnetic flux φ2.

[0010]

Number

[0011] The speed calculation unit 6 outputs the calculated induction machine speed ωm to the adder 8.

[0012] The slip frequency command generation unit 7 receives the magnetic flux command F2 indicating the magnetic flux of the induction machine 1 and the torque command TQ indicating the torque of the induction machine 1. Based on the magnetic flux command F2 and the torque command TQ, the slip frequency command generation unit 7 calculates a slip frequency command ωsr indicating the slip frequency of the induction machine 1 according to the following equation (6). ωsr = R2 * TQ / F2 2 Equation (6)

[0013] The slip frequency command generation unit 7 outputs the generated slip frequency command ωsr to the adder 8.

[0014] The adder 8 receives the induction machine speed ωm and the slip frequency command ωsr. The adder 8 adds the induction machine speed ωm and the slip frequency command ωsr to generate a frequency command ωi, and outputs it to the torque control unit 4.

[0015] The current command generation unit 5 receives the magnetic flux command F2 and the torque command TQ. Based on the magnetic flux command F2 and the torque command TQ, the current command generation unit 5 calculates a magnetic flux component current command Id and a torque component current command Iq according to the following equations (7) and (8). Id = F2 / M Equation (7) Iq = L2 / M * TQ / F2 Equation (8)

[0016] The current command generation unit 5 outputs the generated magnetic flux component current command Id and torque component current command Iq to the torque control unit 4.

[0017] The torque control unit 4 receives the detection result of the current i by the current detector 2, the frequency command ωi, the flux component current command Id, and the torque component current command Iq. The torque control unit 4 generates a voltage command v based on the frequency command ωi, the current i, the flux component current command Id, and the torque component current command Iq. Specifically, the torque control unit 4 generates a voltage command v such that the current i becomes the flux component current command Id and the torque component current command Iq, and outputs it to the power converter 3 and the speed calculation unit 6.

[0018] The power converter 3 amplifies the voltage command v input from the torque control unit 4 and outputs it to the induction machine 1 which is the load.

[0019] With the above-described configuration, the flux and torque of the induction machine 1 can be controlled according to the flux command F2 and the torque command TQ.

Prior Art Documents

Patent Documents

[0020]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0021] In the conventional induction machine control device 10, when starting the induction machine 1 in the forward direction with the torque command TQ ≥ 0 from the state where the induction machine 1 is stopped, consider the case where the primary resistance reference value R1N is larger than the actual primary resistance value R1r of the induction machine 1. In this case, the above-described formula (1) can be expressed by the following formula (9).

[0022]

Equation

[0023] Here, φ2r is the actual flux of the induction machine 1, and t is the calculation time.

[0024] When the torque command TQ is small and the magnitude of the phase difference between the magnetic flux and the current of the induction machine 1 is near 0 degrees, since L2 / M*(R1N - R1r)>0, from Equation (9), the magnitude of the calculated magnetic flux φ2 is smaller than the actual magnetic flux φ2r. When the magnitude of the calculated magnetic flux φ2 becomes smaller than the actual magnetic flux φ2r, in Equation (4), the denominator becomes smaller, so ωs is calculated on the larger side. As a result, in Equation (5), the induction machine speed ωm is calculated to be smaller than the actual value. Since the primary resistance value R1r of the induction machine 1 varies depending on the temperature of the induction machine 1 etc., when the difference between the primary resistance reference value R1N and the actual primary resistance value R1r of the induction machine 1 becomes large, there is a possibility that the induction machine speed ωm<0, and it is also conceivable that the frequency command ωi<0. Due to such a calculation error occurring in the induction machine speed ωm, the accuracy of torque control of the induction machine 1 will decrease, and in the worst case, there is a risk that the induction machine 1 will reverse (rotate in the reverse direction with respect to the forward rotation command).

[0025] Even when starting the induction machine 1 in reverse with the torque command ≤0 from the state where the induction machine 1 is stopped, considering in the same way, the accuracy of torque control of the induction machine 1 will decrease, and in the worst case, there is a risk that the induction machine 1 will rotate forward (rotate in the reverse direction with respect to the reverse rotation command).

[0026] In view of the above problems, an object of the present invention is to provide an induction machine control device that can improve the accuracy of torque control of the induction machine and prevent the induction machine from rotating in the reverse direction with respect to the command.

Means for Solving the Problems

[0027] To solve the above problems, an induction machine control device according to the present invention is an induction machine control device for controlling an induction machine, including a current detector for detecting a current flowing through the induction machine, a primary resistance set value of the induction machine, a current detected by the current detector, and a voltage command for instructing an output voltage to the induction machine. A speed calculation unit that calculates the induction machine speed and the magnitude of the calculated magnetic flux of the induction machine based on these; a slip frequency command generation unit that generates a slip frequency command for instructing the slip frequency of the induction machine based on a magnetic flux command and a torque command; an adder that generates a frequency command by adding the induction machine speed and the slip frequency command; a current command generation unit that generates a magnetic flux component current command and a torque component current command based on the magnetic flux command and the torque command; a torque control unit that generates the voltage command based on the frequency command, the current detected by the current detector, the magnetic flux component current command, and the torque component current command; an excitation determination unit that generates an excitation elapsed time, which is the time until the ratio of the magnitude of the calculated magnetic flux to the magnetic flux command reaches a predetermined value; and a primary resistance setting unit that sets the primary resistance set value based on the excitation elapsed time.

[0028] Further, in the induction machine control device according to the present invention, the primary resistance setting unit sets a primary resistance reference value as the primary resistance set value until the excitation elapsed time exceeds a predetermined value, and when the excitation elapsed time exceeds the predetermined value, sets a value obtained by multiplying the primary resistance reference value by a positive number less than 1 as the primary resistance set value.

[0029] Also, in the induction machine control device according to the present invention, when the current is i, the voltage command is v, the primary resistance set value is R1S, the secondary resistance of the induction machine is R2, the primary self-inductance is L1, the secondary self-inductance is L2, and the mutual inductance is M, the speed calculation unit calculates the induction machine magnetic flux φ2C by the following formula (10). When the induction machine speed is ωm, and the a-axis component and b-axis component of the induction machine magnetic flux φ2C are FAC and FBC respectively, the induction machine speed ωm is calculated by the following formulas (11) to (14).

Equation

Advantages of the Invention

[0030] According to the induction machine control device of the present invention, it is possible to improve the accuracy of torque control of the induction machine and prevent the induction machine from rotating in the reverse direction with respect to the command.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0032] Hereinafter, modes for carrying out the present invention will be described with reference to the drawings.

[0033] FIG. 1 is a diagram showing the configuration of an induction machine control device 100 according to an embodiment of the present disclosure. In FIG. 1, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

[0034] As shown in FIG. 1, the induction machine control device 100 according to the present embodiment includes a current detector 2, a power converter 3, a torque control unit 4, a current command generation unit 5, a speed calculation unit 106, a slip frequency command generation unit 7, an adder 8, an excitation determination unit 101, and a primary resistance setting unit 102. The induction machine control device 100 according to the present embodiment is different from the conventional induction machine control device 10 shown in FIG. 2 in that the speed calculation unit 6 is changed to the speed calculation unit 106 and the excitation determination unit 101 and the primary resistance setting unit 102 are added.

[0035] The speed calculation unit 106 receives the detection result of the current i by the current detector 2, the voltage command v, and the primary resistance setting value R1S of the induction machine 1 output from a primary resistance setting unit 102, which will be described later. Based on the primary resistance setting value R1S, the current i, and the voltage command v, the speed calculation unit 106 calculates the induction machine speed ωm and the induction machine flux φ2C according to the following equations (10) to (14). In Equation (12), FAC and FBC are the a-axis component and b-axis component of the induction machine flux φ2C, respectively.

[0036] [Number]

[0037] Also, the speed calculation unit 106 calculates a calculated flux magnitude φ2v according to the following equation (15).

[0038] [Number]

[0039] The speed calculation unit 106 outputs the calculated induction machine speed ωm to the adder 8 and outputs the calculated calculated flux magnitude φ2v to the excitation determination unit 101.

[0040] The excitation determination unit 101 receives the flux command F2 and the calculated flux magnitude φ2v. The excitation determination unit 101 generates an excitation elapsed time tF, which is the time until the ratio of the calculated flux magnitude φ2v to the flux command F2 reaches an excitation threshold A (a predetermined value). Specifically, assuming F_Ratio = φ2v / F2, the excitation determination unit 101 sets the time when F_Ratio < A as the excitation elapsed time tF. Note that when F_Ratio ≥ A, the excitation determination unit 101 holds the excitation elapsed time tF. The excitation determination unit 101 outputs the excitation elapsed time tF to the primary resistance setting unit 102. The excitation threshold A is a constant between 0 and 1.

[0041] The primary resistance setting unit 102 receives the excitation elapsed time tF and the primary resistance reference value R1N. The primary resistance setting unit 102 sets a primary resistance set value R1S based on the excitation elapsed time tF and outputs it to the speed calculation unit 106. Specifically, the primary resistance setting unit 102 sets the primary resistance reference value R1N as the primary resistance set value R1S until the excitation elapsed time tF exceeds the excitation reference time tF0 (a predetermined value). Also, when the excitation elapsed time tF exceeds the excitation reference time tF0, the primary resistance setting unit 102 sets a value obtained by multiplying the primary resistance reference value R1N by B (B is a positive number less than 1) (= B*R1N) as the primary resistance set value R1S.

[0042] Next, the operation of the induction machine control device 100 according to this embodiment will be described.

[0043] First, the case where the error between the primary resistance reference value R1N and the actual primary resistance value R1r is small will be described. In this case, the error between the induction machine flux φ2C in the above-described formula (10) and the actual flux φ2r is small. Therefore, the calculated flux magnitude φ2v substantially coincides with the magnitude of the actual flux φ2r. At this time, if the excitation threshold A is set so that tF < tF0, then due to the operations of the excitation determination unit 101 and the primary resistance setting unit 102, R1S = R1N always holds. The error in the induction machine speed ωm calculated by formulas (10) to (14) is also small, and good torque control accuracy of the induction machine 1 can be obtained.

[0044] Next, the case where the relationship between the primary resistance reference value R1N and the actual primary resistance value R1r is R1N < R1r will be described. The excitation threshold A and the excitation reference time tF0 are set to the values set when the error between the above-described primary resistance reference value R1N and the actual primary resistance value R1r is small.

[0045] In Equation (9), if the magnitude of the phase difference between the magnetic flux and the current of the induction machine 1 is within 90 degrees, then L2 / M*(R1N - R1r) < 0, so the calculated magnetic flux magnitude φ2v becomes larger than the actual magnetic flux φ2r. Then, in Equation (13), due to the increase in the denominator, ωsc is calculated to be on the smaller side, and in Equation (14), the induction machine speed ωm is calculated to be larger than the actual value. For this reason, the frequency command ωi becomes larger, but no reverse torque is output to the induction machine 1. Therefore, when starting operation from the state where the induction machine 1 is stopped, it is possible to prevent it from starting to rotate in the reverse direction.

[0046] The calculated magnetic flux magnitude φ2v increases faster than the actual magnetic flux φ2r, so tF < tF0 and F_Ratio ≧ A. Therefore, due to the operations of the excitation determination unit 101 and the primary resistance setting unit 102, R1S = R1N always holds. The induction machine speed ωm calculated by Equations (10) to (14) is calculated to be larger than the actual value. For this reason, the frequency command ωi also becomes larger, but no reverse torque is output to the induction machine 1. Therefore, when starting operation from the state where the induction machine 1 is stopped, it is possible to prevent it from starting to rotate in the reverse direction.

[0047] Next, the case where the relationship between the primary resistance reference value R1N and the actual primary resistance value R1r is R1N > R1r will be described. In Equation (9), when the magnitude of the phase difference between the magnetic flux and the current of the induction machine 1 is near 0 degrees, since L2 / M * (R1N - R1r) > 0, the calculated magnetic flux magnitude φ2v is smaller than the magnitude of the actual magnetic flux φ2. Here, if the excitation threshold A and the excitation reference time tF0 are set so that tF ≥ tF0, after the elapse of the excitation reference time tF0, due to the operations of the excitation determination unit 101 and the primary resistance setting unit 102, the primary resistance setting value R1S = B * R1N. Considering the fluctuation range of the primary resistance of the induction machine 1, if the value of B is set so that R1S ≤ R1r, the error of the induction machine speed ωm calculated by Equations (10) to (14) becomes smaller, or becomes larger than the actual value. If the error of the induction machine speed ωm is small, the accuracy of the torque control of the induction machine 1 can be improved. Also, even if the induction machine speed ωm is calculated to be larger than the actual value, when the induction machine 1 starts operating from a stopped state, it is possible to prevent it from starting to rotate in the reverse direction.

[0048] Note that it is desirable to set the excitation reference time tF0 so that R1S = B * R1N before the frequency command ωi changes sign.

[0049] As described above, the induction machine control device 100 according to this embodiment includes an excitation determination unit 101 that generates an excitation elapsed time tF, which is the time until the ratio of the calculated magnetic flux magnitude φ2v to the magnetic flux command F2 reaches a predetermined value (excitation threshold A), and a primary resistance setting unit 102 that sets a primary resistance setting value R1S based on the excitation elapsed time tF.

[0050] By having such a configuration, the primary resistance setting value R1S can be controlled according to the error between the primary resistance reference value R1N and the actual primary resistance value R1r. Thus, the accuracy of the torque control of the induction machine 1 can be improved, and it is possible to prevent the induction machine 1 from rotating in the reverse direction with respect to the command.

[0051] Although the above-described embodiments have been described as representative examples, it will be apparent to those skilled in the art that many changes and substitutions are possible within the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes are possible without departing from the scope of the claims.

Explanation of Reference Numerals

[0052] 1 Induction machine 2 Current detector 3 Power converter 4 Torque control unit 5 Current command generation unit 6 Speed calculation unit 7 Slip frequency command generation unit 8 Adder 10 Induction machine control device 100 Induction machine control device 101 Excitation determination unit 102 Primary resistance setting unit 106 Speed calculation unit

Claims

1. An induction machine control device for controlling an induction machine, comprising: a current detector for detecting a current flowing through the induction machine; a speed calculation unit that calculates an induction machine speed and a calculated magnetic flux magnitude of the induction machine based on a primary resistance set value of the induction machine, a current detected by the current detector, and a voltage command for instructing an output voltage to the induction machine; a slip frequency command generation unit that generates a slip frequency command for instructing a slip frequency of the induction machine based on a magnetic flux command and a torque command; an adder that generates a frequency command obtained by adding the induction machine speed and the slip frequency command; a current command generation unit that generates a magnetic flux component current command and a torque component current command based on the magnetic flux command and the torque command; a torque control unit that generates the voltage command based on the frequency command, the current detected by the current detector, the magnetic flux component current command, and the torque component current command; an excitation determination unit that generates an excitation elapsed time, which is a time until a ratio of the calculated magnetic flux magnitude to the magnetic flux command reaches a predetermined value; a primary resistance setting unit that sets the primary resistance set value based on the excitation elapsed time. An induction machine control device comprising the above components.

2. In the induction machine control device according to Claim 1, the primary resistance setting unit sets a primary resistance reference value as the primary resistance set value until the excitation elapsed time exceeds a predetermined value, and when the excitation elapsed time exceeds the predetermined value, sets a value obtained by multiplying the primary resistance reference value by a positive number less than 1 as the primary resistance set value. An induction machine control device.

3. In the induction machine control device according to Claim 1, assuming the current is i, the voltage command is v, the primary resistance set value is R1S, the secondary resistance of the induction machine is R2, the primary self-inductance is L1, the secondary self-inductance is L2, and the mutual inductance is M, the speed calculation unit calculates an induction machine magnetic flux φ2C by the following formula (1), assuming the induction machine speed is ωm, and the a-axis component and b-axis component of the induction machine magnetic flux φ2C are FAC and FBC respectively, calculates the induction machine speed ωm by the following formulas (2) to (5). An induction machine control device. 【Number 1】

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