JP3301189B2 - Command converter for power converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter such as a power regulator and a reactive power compensator using a semiconductor device.
The present invention relates to a command value limiting circuit for limiting three-phase command values so that three-phase voltages and currents do not exceed predetermined values.

[0002]

2. Description of the Related Art FIG. 4 is a schematic block diagram of a control system such as a power regulator and a reactive power compensator. In FIG. 4, reference numeral 10 denotes a power converter such as an inverter or a converter;
Reference numeral 20 denotes a control device for the power converter 10. The control device 20 receives the three-phase command values for the three-phase voltage and current and the three-phase detection values such as the three-phase output voltage and current of the power converter 10, and outputs two positive and negative phase axes (quadrature d). A detecting unit 21 for generating a voltage / current command value of a (q rotation coordinate axis) component, a limiting unit 22 for limiting these command values to a predetermined range, and adjusting the output of the power converter 10 according to the limited command values. The control unit includes an adjusting unit 23 and a pulse shaping unit 24 that generates a pulse signal to be applied to the semiconductor element of the power converter 10 based on the output of the adjusting unit 23.

The detecting section 21 has a positive / negative phase component detection circuit described in Japanese Patent Application No. 5-47472 filed by the present applicant. To a two-phase signal, and a positive-phase vector rotation in the same direction and at the same speed as the system voltage on the orthogonal dq rotation coordinate axis with respect to the output of the three-phase / two-phase conversion circuit. And a positive-phase vector converter that converts the three-phase electric quantity into a positive-phase component,
A negative-phase vector converter that performs reverse-phase vector rotation in the opposite direction at the same speed as the system voltage on the -q rotation coordinate axis to convert it into a negative-phase component of a three-phase electric quantity; A moving average filter circuit for continuously obtaining an average value over a half cycle of the system fundamental frequency, wherein the positive phase component and the negative phase component obtained by the positive phase vector converter and the negative phase vector converter are filtered by the filter circuit. To remove even harmonic components of the system fundamental frequency.

[0004] As the limiter 22, a structure shown in Figs. 5 and 6 has been conventionally known. In the limiting unit shown in FIG. 5, first, the positive-phase combined component is calculated from the input positive-phase d-axis command value and positive-phase q-axis command value using the two-axis combining calculator 31. On the other hand, an arbitrary command limit value A set by the limit value setter 33 is input to the divider 35, which divides the command limit value A by the positive-phase combined component to determine a limit rate for limiting the input command value. Is done. This limiting rate is input to multipliers 39 and 40 via a limiting device 37, and the positive phase d
By multiplying by the axis command value and the positive-phase q-axis command value, respectively, the positive-phase d-axis command value and the positive-phase q-axis command value are limited to values that do not exceed the command limit value A. Similarly, for the negative-phase d-axis command value and the negative-phase q-axis command value, the two-axis combining calculator 32, the limit value setter 34, the divider 36, the limiter 38, and the multipliers 41, 4
By using 2, the command limit value A is limited to a value that does not exceed the command limit value A.

Here, the limiters 37 and 38 operate when the positive-phase or negative-phase combined component is equal to or less than the command limit value A.
This is to suppress the output to 1 or less in order to prevent the outputs of 5, 36 from amplifying the command value exceeding 1.

In the limiting unit shown in FIG. 6, similarly to FIG. 5, the combined components of the normal phase and the negative phase are calculated by the two-axis combining calculators 55 and 56. Then, the limit value setting devices 57 and 58
PI (proportional / integral) adjusters 59 and 60 perform an adjusting operation so that the deviation between the command limit value A and the combined component becomes zero, and when the combined component> command limit value A, the PI controller 5
As a result of limiting the signals output from the signals 9 and 60 to values of 0 or more and 1 or less by the limiters 61 and 62, the multipliers 51 to 54 multiply the positive and negative d-axis and q-axis command values by: Each command value is limited to a value that does not exceed the command limit value A. When the combined component is equal to or less than the command limit value A, the limiters 61 and 62 do not amplify the respective command values via the multipliers 51 to 54 because the output signals of the PI adjusters 59 and 60 become larger than 1. It is to make.

[0007]

In each of the above prior arts, a series of command value limiting operations are performed continuously, and the changing positive phase and negative phase command values are individually limited. . However, according to these methods, the positive and negative phase components are limited by the command limit value A, but the combined components (three-phase electric quantities) of the input command value are restricted by the positive and negative phases. The configuration (when both the positive-phase combined component and the negative-phase combined component are not zero) exceeds the command limit value A, and the three-phase output (three-phase output voltage and current) of the power converter 10 is the command limit value A. May not be restricted.

As described above, in the conventional limiting method, the three-phase output of the power converter 10 may not be limited by the command limit value A. Therefore, the command limit value A is set to the power system protection level or the load overload level. If so, overloading the power system and load becomes a problem. In addition, when the command limit value A is set in correspondence with the rated value of the power converter 10, there is a problem that the power converter 10 is in an output state equal to or higher than the rated value.

The present invention has been made to solve the above problems, and an object of the present invention is to prevent a three-phase output of a power converter from exceeding a command limit value, a power system, a load, and a power conversion device. It is an object of the present invention to provide a command value limiting circuit for a power converter which protects a power converter or the like.

[0010]

In order to achieve the above object, a first aspect of the present invention is to decompose a positive-phase component and a negative-phase component of a three-phase electric quantity into quadrature dq rotation coordinate axis components and convert them into power converters. A command value limiting circuit of a power converter for controlling the positive-phase d-axis command value, the positive-phase q-axis command value, the negative-phase d-axis command value, and the negative-phase q-axis command value to values not exceeding the command limit value. A first limiter for individually limiting each command value based on the command limit value, and converting each command value output from the first limiter into a three-phase electric quantity output from the power converter, By comparing the phase electric quantity with the command limit value, the negative phase d-axis command value and the negative phase q-axis command value are restricted, and the positive phase d-axis command value and the positive phase q-axis command value are given priority without restriction. Or output the positive phase d-axis command value and the positive phase by comparing the three-phase electric quantity with the command limit value. Those having a priority restricting unit to give priority to output without limiting the reverse-phase d-axis command value and the negative phase q-axis command value with respect to the axis command value to limit.

According to a second aspect of the present invention, there is provided a first limitation for individually limiting a positive-phase d-axis command value, a positive-phase q-axis command value, a negative-phase d-axis command value, and a negative-phase q-axis command value based on a command limit value. Unit and each command value output from the first limiting unit is converted into a three-phase electric quantity output from the power converter, and by comparing this three-phase electric quantity with the command limit value, all command values are converted. And an equal-ratio restricting unit for restricting at an equal ratio.

According to a third aspect of the present invention, there is provided a first limitation for individually limiting a positive-phase d-axis command value, a positive-phase q-axis command value, a negative-phase d-axis command value, and a negative-phase q-axis command value based on a command limit value. Unit and each command value output from the first limiting unit are converted into a three-phase electric quantity output from the power converter, and the three-phase electric quantity is compared with the command limit value to obtain a positive-phase d-axis command. And a positive-phase q-axis command value, and an arbitrary ratio restricting unit that restricts the negative-phase d-axis command value and the negative-phase q-axis command value at arbitrary restriction ratios.

[0013]

According to the first aspect of the present invention, the positive and negative phase d-axes, q
When the axis command values exceed the command limit values, the first limiter individually limits these command values. Also,
When the three-phase electric quantity converted from each command value exceeds the command limit value, the command value of the positive phase is prioritized, and the command value of the negative phase is limited.

In the second invention, when each command value exceeds the command limit value, these command values are individually limited by the first limiting unit as in the first invention. When the three-phase electric quantity converted from each command value exceeds the command limit value, the command value is restricted at the same ratio for both the positive and negative phase command values, and almost the original command value is input. Limit to similar values.

In the third invention, when each command value exceeds the command limit value, each of the command values is individually limited by the first limiting unit as in the first invention. If the three-phase electric quantity converted from each command value exceeds the command limit value, the command value of the positive phase and the command value of the negative phase are respectively limited at an arbitrary ratio.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a block diagram showing an embodiment of the first invention. In FIG. 1, L1 is a first limiting unit, which has the same configuration as the limiting unit using the divider of FIG. As the limiter L1, a limiter using the controller of FIG. 6 may be used, and in any case, a conventional limiter is used.

Next, L2 is a priority restriction unit as a newly added second restriction unit. This priority limiting unit L2
Each command value after the limit output from the first limit unit L1 is converted into a three-phase electric quantity output from the power converter 10 and compared with the limit command value to obtain a two-axis command value of a positive phase or a negative phase. This embodiment has a function of limiting, and in this embodiment, this function is added to the conventional individual limiting function of the normal phase component and the negative phase component by the first limiting section L1.

The priority limiter L2 includes multipliers 71-74 to which the respective command values after the limit output from the first limiter L1 are input, and a phase calculator 75 to which the output signal is input. A two-axis synthesis calculator 76 to 78 to which the two-axis component of each phase electric quantity as an output thereof is input, a maximum output calculator 79 to which these outputs are input, a limit value setter 80, An addition point 81 for obtaining a deviation between the value A and the output of the maximum output calculator 79, a PI adjuster 82 that performs an adjustment operation to make the deviation zero, a limiter 83 on the output side thereof, and a limiter 83 It is composed of a positive-phase limit switch 84 and a negative-phase limit switch 85, which are closed to multiply the output by the respective command values after the restriction by the first restriction unit L1.

Here, in the priority restriction, the output three-phase electric quantity of the power converter converted from the input command values (positive-phase and negative-phase d-axis and q-axis command values) exceeds the command limit value A. In this case, a limit is applied to each of the negative-phase axis command values, and a positive-phase priority limit is output to each of the positive-phase axis command values. In addition, there is a reverse-phase priority restriction in which a restriction is imposed and each axis command value in the reverse phase is output with priority without restriction. Hereinafter, the contents of these two priority restrictions will be described.

(1) Positive-phase Priority Restriction To set conditions for positive-phase priority, the positive-phase limit switch 84 is opened and the negative-phase limit switch 85 is closed.
3, 34 and 80, all the command limit values A are set to predetermined identical values. The operation and function of the first restriction unit L1 are the same as those described with reference to FIG. on the other hand,
In the priority limiting unit L2, each phase calculator 75 calculates the command values of the positive-phase d-axis, the positive-phase q-axis, the negative-phase d-axis, and the negative-phase q-axis limited by the first limiting unit L1, The biaxial components of the normal phase and the negative phase are converted into biaxial components of each of the R, S, and T phases. The converted values are input to the two-axis combining calculators 76 to 78, and the combined components of the R, S, and T phases (three-phase electric quantities corresponding to the output of the power converter) are calculated. The arithmetic expression of each phase is derived by the following method.

According to the above-mentioned Japanese Patent Application No. 5-47472, the DC components of the two axes of the positive phase and the negative phase are, for example, in the case of a current component, the formula 1 for the positive phase and the formula 2 for the negative phase. Can be represented. In these equations, I _Pd is a positive-phase d-axis current component, I _Pq is a positive-phase q-axis current component, I _Nd is a negative-phase d-axis current component, I _Nq is a negative-phase q-axis current component, and I _P is positive phase current component peak value, the I _N reversed phase current component peak value, the [psi _P positive phase current component phase difference, the [psi _N is reverse-phase current component phase difference.

[0022]

(Equation 1)

[0023]

(Equation 2)

When the R-phase current i _R composed of the positive-phase component and the negative-phase component is obtained from these equations, the following equation 3 is obtained. Note that A _R , B _R , and ψ _R in Expression 3 are as shown in Expressions 4 to 6.

[0025]

Equation 3] _{i R = I P cos (ωt} + ψ P) + I N cos (ωt + ψ N) = {√ (A R 2 + B R 2)} cos (ωt + ψ R)

[0026]

[Number 4] _{A R = I P cosψ P +} I N cosψ N

[0027]

[Number 5] _{B R = I P sinψ P +} I N sinψ N

[0028]

[6] ^{_{ψ R = tan -1 (B R}} / A R)

The relationship between the R-phase current (stationary coordinate system) and the R-phase biaxial component can be expressed by the following equation (7).
Can be treated as I _rd = A _R , I _rq = B _R , ψ _r = tan ^-1 (B _R / A _R ) = ψ _R.

[0030]

Equation 7] _{i R = I rd + jI rq} = {√ (I rd 2 + I rq 2)} (cosψ r + jsinψ r)

Similarly, the S-phase current i _S is calculated by the following equation (8) under the conditions of the equations (9) to (11).
The phase current i _T is expressed by Expression 12 under the conditions of Expressions 13 to 15.

[0032]

Equation 8] _{i S = I P cos (ωt} + ψ P -2π / 3) + I N cos (ωt + ψ N + 2π / 3) = A S cos (ωt + 2π / 3 + ψ S) -B S sin (ωt-2π / 3 + ψ S)

[0033]

Equation 9] _{A S = I P cosψ P +} I N cos (ψ N + 4π / 3)

[0034]

Equation 10] _{B S = I P sinψ P +} I N sin (ψ N + 4π / 3)

[0035]

数_S = tan ^-1 (B _S / A _S )

[0036]

Equation 12] _{i T = I P cos (ωt} + ψ P -4π / 3) + I N cos (ωt + ψ N + 4π / 3) = A T cos (ωt-4π / 3 + ψ T) -B T sin (ωt-4π / 3 + ψ _T )

[0037]

Equation 13] _{A T = I P cosψ P +} I N cos (ψ N + 2π / 3)

[0038]

Equation 14] _{B T = I P sinψ P +} I N sin (ψ N + 2π / 3)

[0039]

１５ _T = tan ^-1 (B _T / A _T )

The R-phase, S-phase, and T-phase currents represented by the above equations 3, 8, and 12 are input to the maximum value output calculator 79, and the maximum value is selectively output. Next, the addition point 81
Thus, a deviation between the command limit value A and the maximum value is calculated. When the deviation is zero or positive (maximum value ≦ command limit value A), the limiter 83 on the output side of the PI controller 82 sets 1 through the negative phase limit switch 85 to the negative phase d-axis command value and The negative-phase q-axis command value is multiplied. As a result, the negative-phase two-axis command value is not limited. On the other hand, if the deviation is negative (maximum value> command limit value A), the limiter 83 does not limit the value of 0 or more and 1 or less. The phase q-axis command value is multiplied by the same amount of signal of 0 or more and 1 or less to limit the negative-phase two-axis command value. Note that the above series of operations is performed continuously.

As described above, the positive-phase priority restriction of the present embodiment restricts the two-axis components of the normal phase and the negative phase exceeding the command restriction value A among the command values by the first restriction unit L1. Part L
In the method 2, while the amount exceeding the command limit value A as the three-phase electric quantity is limited to the negative phase command value, the normal phase command value is output as it is with priority.

(2) Negative-phase priority restriction As a condition setting for negative-phase priority, the positive-phase restriction switch 84 is closed, the negative-phase restriction switch 85 is opened, and the limit value setting unit 3
3, 34 and 80, all the command limit values A are set to predetermined identical values. In the priority restriction unit L2, the first restriction unit L
Each of the command values of the positive phase d axis, the positive phase q axis, the negative phase d axis, and the negative phase q axis limited by The phase, S phase, and T phase are converted into biaxial components. The converted values are input to the two-axis combining calculators 76 to 78, and the combined components of the R, S, and T phases are calculated.

Next, similarly to the above, the R-phase, S-phase, and T-phase currents are input to a maximum value output calculator 79, the maximum value is selected and output, and the difference between the command limit value A and the maximum value is determined by an addition point 81. Is calculated. When the deviation is zero or positive (maximum value ≦ command limit value A), the positive-phase d-axis command value and the positive-phase q-axis command value are multiplied by 1 by the limiter 83 on the output side of the PI controller 82. That is, there is no limit on the positive-phase two-axis command value. On the other hand, if the deviation is negative (maximum value> command limit value A), the limiter 82 does not limit the value of 0 or more and 1 or less. Then, the positive-phase two-axis command value is limited by multiplying the positive-phase d-axis command value and the positive-phase q-axis command value by the same amount of signal of 0 or more and 1 or less. Note that the above series of operations is performed continuously.

As described above, the negative-phase priority restriction according to the present embodiment restricts the positive-phase and negative-phase two-axis components exceeding the command restriction value A among the command values by the first restriction unit L1, and further restricts the priority. Part L
In the method 2, the amount exceeding the command limit value A as the three-phase electric quantity is limited to the positive-phase command value, while the negative-phase command value is output with priority as it is.

Next, an embodiment of the second invention will be described with reference to FIG. This embodiment is substantially the same as the normal-phase limit switch 84 and the negative-phase limit switch 85 in FIG. 1 which are always closed. In this case, the two-axis command values for both the normal phase and the negative phase are restricted at an equal ratio using the signal passed through the device 83. Also in this embodiment, the first
May be configured by a restrictor using an adjuster as shown in FIG.

As the operation, the limit value setting units 33 and 3
4, the command limit value A is set to the same predetermined value. The equal-ratio limiting unit L21 performs the same operation as described above based on the positive-phase d-axis command value, the positive-phase q-axis command value, the negative-phase d-axis command value, and the negative-phase q-axis command value restricted by the first limiting unit L1. Each phase calculator 75, two-axis composite calculators 76 to 78, maximum output calculator 79
, The maximum value among the R-phase, S-phase, and T-phase currents is calculated. Then, the output of the PI adjuster 82 that makes the deviation between the command limit value A and the maximum value zero is input to all the multipliers 71 to 74 via the limiter 83.

Here, when the deviation is zero or positive (maximum value ≦ command limit value A), 1 is set via the limiter 83 to the positive phase d axis command value, the positive phase q axis command value, Axis command value, reverse phase q
Since the axis command value is multiplied, each command value is not limited. When the deviation is negative (maximum value> command limit value A), the limiter 83 does not limit the value of 0 or more and 1 or less, so that the positive-phase d-axis command value and the positive-phase q-axis until the deviation becomes zero. The command value, the negative-phase d-axis command value, and the negative-phase q-axis command value are multiplied by the same amount of 0 to 1 signal to limit each command value. Note that the above series of operations is performed continuously.

As described above, this equi-ratio restriction is based on the fact that the positive-phase component and the negative-phase component that exceed the command
In addition, the amount exceeding the command limit value A as a three-phase electric quantity is further restricted at an equal ratio with respect to all the command values of the normal phase and the negative phase. As a result, each command value after restriction output from the arbitrary ratio restriction unit L22 is equal to the first command value.
Are substantially similar to the respective command values output from the limiter L1.

Next, an embodiment of the third invention will be described with reference to FIG. In this embodiment, in the arbitrary ratio limiting unit L22 as the second limiting unit, the limiting ratios B and C for the command values of the normal phase and the negative phase are arbitrarily set under the condition of Expression 16. . Note that B is a negative phase restriction ratio set by the negative phase restriction ratio setting device 86, and C is a positive phase restriction ratio set by the positive phase restriction ratio setting device 87. These ratios are set in the range of 1 ≧ B ≧ 0 and 1 ≧ C ≧ 0.

[0050]

## EQU16 ## B + C = 1

However, the minimum value (minimum value other than 0) of the input limiting ratios B and C is a set input value that becomes 1 or more even when multiplied by the saturation value (maximum output value) _Pmax of the PI controller 82. (Condition of Expression 17). This is to prevent the command value from being limited by the influence of the limiting ratio when the minimum value <the command limit value A.

[0052]

## EQU17 ## Minimum value of restriction ratio (excluding 0) ≧ 1 / P _max

Here, the command limit value A set by the limit value setting units 33, 34 and 80 is the same predetermined value as described above. Also in this embodiment, the first restricting unit L1 may be configured by a restricting unit using an adjuster as shown in FIG.

The operation will be described. When the deviation is positive (maximum value ≦ command limit value A), the output of the PI controller 82 saturates to +, and the positive phase limit ratio C and the negative phase limit ratio B The 1 is multiplied by the positive phase d-axis command value, the normal phase q-axis command value, the negative phase d-axis command value, and the negative phase q-axis command value via the limiting ratio and the limiter 83 of the output. There is no limit on the value.
When the deviation is negative (maximum value> command limit value A), the output of the PI controller 82 decreases, and the signal via the limit ratio does not limit the signal of 1 or less in the limiter 83. Until it becomes zero, the limiting ratio C is multiplied for the positive-phase d-axis command value and the positive-phase q-axis command value, and the limit is applied for the negative-phase d-axis command value and the negative-phase q-axis command value. Each command value is limited by multiplying a signal (0 or more and 1 or less) obtained by multiplying the ratio B. Note that the above series of operations is performed continuously.

As described above, in the arbitrary ratio limitation of the present embodiment, the positive and negative phase components exceeding the command limit value A among the respective command values are limited by the first limiter L1. The amount of the electric quantity exceeding the command limit value A is limited by the arbitrary limit ratios C and B with respect to the normal phase and the negative phase command values.

[0056]

As described above, according to the present invention, the first limiting unit using the conventional divider or regulator and the second limiting unit comprising the priority limiting unit, the equal ratio limiting unit or the arbitrary ratio limiting unit. In addition to individually limiting the positive-phase and negative-phase components of three-phase voltage and three-phase current including unbalance, the three-phase electric quantity of the combined component is also commanded It can be suppressed to within the value, and the power system, the load, and the power converter can be reliably protected.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing an embodiment of the second invention.

FIG. 3 is a block diagram showing an embodiment of the third invention.

FIG. 4 is a schematic block diagram of a control system to which the related art is applied.

FIG. 5 is a block diagram showing a conventional restriction unit.

FIG. 6 is a block diagram showing a conventional restriction unit.

[Explanation of symbols]

 L1 First limiting unit L2 Priority limiting unit L21 Equal ratio limiting unit L22 Arbitrary ratio limiting unit 10 Power converter 20 Control unit 21 Detecting unit 22 Limiting unit 23 Adjusting unit 24 Pulse shaping unit 31, 32, 76 to 78 Biaxial synthesis Arithmetic units 33, 34, 80 Limit value setting units 35, 36 Dividers 37, 38, 83 Limiters 39 to 42 Multipliers 51 to 54 Dividers 55, 56 Biaxial synthesis arithmetic units 57, 58 Limit value setting units 59, Reference Signs List 60 PI adjuster 61, 62 Limiter 71-74 Multiplier 75 Each phase calculator 76-78 Two-axis composite calculator 79 Maximum value output calculator 80 Limit value setter 81 Addition point 82 PI adjuster 84 Normal phase limit switch 85 Negative-phase limit switch 86 Negative-phase limit ratio setting device 87 Positive-phase limit ratio setting device

Continuation of the front page (56) References JP-A-6-189456 (JP, A) JP-A-4-344172 (JP, A) JP-A-6-245383 (JP, A) JP-A-6-233464 (JP) JP-A-4-271226 (JP, A) JP-A-62-201515 (JP, A) JP-A-5-41347 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H02J 3/00-5/00 G01R 29/16 H02H 3/34

Claims (3)

(57) [Claims] 1. The normal phase and the negative phase components of a three-phase electric quantity are orthogonal d-
Decompose them into q-axis coordinate axis components, and divide these into a positive-phase d-axis command value, a positive-phase q-axis command value, a negative-phase d-axis command value for the power converter,
A command value limiting circuit for a power converter that controls the negative-phase q-axis command value to a value not exceeding the command limit value, wherein the first and second command values are individually limited based on the command limit value.
Each of the command values output from the first limiting unit is converted into a three-phase electrical quantity corresponding to the output of the power converter, and the three-phase electrical quantity is compared with the command limiting value to obtain a negative-phase d-axis. The command value and the negative-phase q-axis command value are restricted, and the positive-phase d-axis command value and the positive-phase q
The axis command value is preferentially output without limitation, or the three-phase electric quantity is compared with the command limit value to output the positive phase d.
A priority limiting unit that limits the axis command value and the positive-phase q-axis command value and outputs the negative-phase d-axis command value and the negative-phase q-axis command value with priority without restriction. A command value limiting circuit for the power converter. 2. The positive-phase and negative-phase components of the three-phase electric quantity are represented by orthogonal d-
Decompose them into q-axis coordinate axis components, and divide these into a positive-phase d-axis command value, a positive-phase q-axis command value, a negative-phase d-axis command value for the power converter,
A command value limiting circuit for a power converter that controls the negative-phase q-axis command value to a value not exceeding the command limit value, wherein the first and second command values are individually limited based on the command limit value.
And the respective command values output from the first limiter are converted into three-phase electric quantities corresponding to the output of the power converter, and all the command values are obtained by comparing the three-phase electric quantities with the command limit values. A command value limiting circuit for a power converter, comprising: 3. The normal phase and the negative phase components of the three-phase electric quantity are orthogonal d−
Decompose them into q-axis coordinate axis components, and divide these into a positive-phase d-axis command value, a positive-phase q-axis command value, a negative-phase d-axis command value for the power converter,
A command value limiting circuit for a power converter that controls the negative-phase q-axis command value to a value not exceeding the command limit value, wherein the first and second command values are individually limited based on the command limit value.
Each of the command values output from the first limiting unit is converted into a three-phase electric quantity corresponding to the output of the power converter, and the three-phase electric quantity is compared with the command limit value to obtain a positive phase d. An arbitrary ratio limiting unit that limits each of the axis command value and the positive-phase q-axis command value and the negative-phase d-axis command value and the negative-phase q-axis command value at an arbitrary limiting ratio. Command value limiting circuit for power converter