JPH10225199A - Control system for power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform vector control by providing only one current detector regardless of the number of phases of a power converter. SOLUTION: Vector control of voltage and current can be carried out regardless of the number of phases of a power converter by providing a current detector 103 only for one arbitrary phase of an N phase (N is an arbitrary integer) power converter and combining a vector regulation means 104, means 105 for estimating the state of an AC network 102 (estimating a current component orthogonal to a current detection value from an orthogonal voltage command 115), coordinate conversion means 106, 107, and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter control system.

[0002]

2. Description of the Related Art FIG. 8 shows a first conventional example of this kind. The power converter 503 is provided with a current detector 103, an AC command generation unit 501, a current adjustment unit 502, and the like. Reference numeral 102 denotes an AC network, and here, as shown in FIG.
Is assumed. That is, in FIG. 8, the power converter 503 performs feedback control of the current detection value by the current adjustment unit 502 so as to match the AC current command output from the AC command generation unit 501, and the single-phase power conversion It is an example of a vessel.

FIG. 10 shows a second conventional example of this type,
2 shows an example of a phase power converter. Here, the power converter 101
, At least two current detectors 103 and 701
Vector adjustment means 104, vector adjustment means 104
Is output from the AC voltage command 11
The first coordinate conversion means 106 for converting the output to 0 and the second coordinate conversion means 107 for converting the outputs of the current detectors 103 and 701 into a current vector 114 are provided.
FIG. 11 shows a specific example of the AC network of FIG.
(A) is a three-phase power supply system or load 801 and filter 8
02 is shown, and FIG. 11B shows an example of an AC motor 803. That is, in FIG. 10, the vector adjustment unit 104 calculates the phase reference 111 (θ) with respect to the stationary coordinate system of the rotating coordinate system according to the operation command 108, and performs feedback control of the current vector 114.

[0004]

Generally, in AC theory, analysis is performed using a phasor. When it is necessary to handle instantaneous values, vectors are used for controlling three-phase and multi-phase devices including the second conventional example, for example. However, phasors and vectors are two-dimensional quantities,
In the case of a single phase as in the first conventional example, a control method based on the vector amount used in the multiphase cannot be applied. In the case of multi-phase as in the second conventional example, at least two current detectors must be provided because two-dimensional vectors need to be handled, and it is difficult to use one current detector. Accordingly, an object of the present invention is to enable phasor or vector-based control using only one current detector regardless of the number of phases of the power converter.

[0005]

In order to solve such a problem, according to the first aspect of the present invention, only one phase of a power converter having an N-side (N is an arbitrary integer) phase AC terminal is provided. A current detector, a vector adjuster that calculates a voltage vector command of the rotating coordinate system, and a second controller that converts the voltage vector command into an orthogonal component (orthogonal voltage command) corresponding to the AC voltage command and the AC voltage command of the current detection phase. 1 coordinate conversion means;
Estimating means for estimating a component (orthogonal current) orthogonal to the current detection value from the orthogonal voltage command, and second coordinate transforming means for calculating a current vector from the estimated orthogonal current and the detected current value. Voltage and current vectors can be controlled based on the output from the coordinate conversion means 2 and the operation command. According to the present invention, the AC voltage command and the detected current value can be input to the estimating means in addition to the quadrature voltage command (the invention of claim 2).

According to a third aspect of the present invention, a current detector provided only in one phase of a power converter having an N-side (N is an arbitrary integer) phase AC terminal, a voltage vector command of a rotating coordinate system and a rotating coordinate system are provided. Vector controller for calculating the phase difference between the system and the stationary coordinate system, and first coordinates for converting the voltage vector command into an orthogonal component (orthogonal voltage command) corresponding to the AC voltage command and the AC voltage command of the current detection phase. Converting means; estimating means for estimating a two-phase current of the detected current value and the quadrature current value from the detected current value, the AC voltage command and the quadrature voltage command; and a second means for converting the two-phase current into a current vector. And the voltage and current vectors can be controlled based on the output from the second coordinate conversion means and the operation command.

Further, according to the present invention, a current detector provided only in one phase of a power converter having an N-side (N is an arbitrary integer) phase AC terminal is provided with a voltage vector command and a voltage vector command for a rotating coordinate system. A vector adjuster for calculating a phase difference between a rotating coordinate system and a stationary coordinate system; coordinate conversion means for converting the voltage vector command into an AC voltage command;
Estimating means for obtaining a current vector estimated value from the phase difference and the current vector, and current vector calculating means for calculating a current vector from the current vector estimated value and the detected current value, and an output from the current vector calculating means. Voltage and current vectors can be controlled based on operation commands. According to the fourth aspect of the present invention, a current detection value can also be input to the estimating means (the fifth aspect of the present invention).

According to a sixth aspect of the present invention, there is provided a current detector provided in only one phase of a power converter having an N-side (N is an arbitrary integer) phase AC terminal, a voltage vector command of a rotating coordinate system and a rotating coordinate system. A vector adjuster for calculating the phase difference between the system and the stationary coordinate system, coordinate conversion means for converting the voltage vector command into an AC voltage command, and a current vector estimation value from a detected current value, the phase difference, and the voltage vector command. And a control unit for controlling a voltage and a current vector based on an output from the estimating unit and an operation command.

[0009]

Before describing the embodiments, the principle of operation of the present invention will be described. It is a common practice to create orthogonal two-axis equation of state from a model of a load or power supply system connected to an AC terminal of a polyphase power converter, or an AC network such as an AC motor. On the other hand, in the case of a single phase, a state equation of two orthogonal axes cannot be created by the AC network alone, but a state equation of a virtual AC network having a state quantity orthogonal to the actual AC network is created. If extended, it becomes possible to create a state equation of two orthogonal axes. Hereinafter, the cases of the first and second inventions will be described. First, in a single phase, it is assumed that the state equation of the AC network is as shown in the following equation (1). In addition, the symbol “•” attached above the code in the equation (1) indicates a differentiation operation.

(Equation 1)

Here, it is assumed that the AC voltage v is equal to the AC voltage command v ^* , and has a relationship represented by the following equation (2) with the voltage vector command v _r ^{* of} the rotating coordinate system rotating at the angular frequency ω. ^{v = v * = (cosθ,} -sinθ) v r * ... (2) _{^{However, v r * = (v d}} *, v q *) T (T indicates that a transposed matrix.) θ = ∫ωdt ^{_{... (3) v d *,}} v q *: d -axis, each of the voltage command of the q-axis (subscript "d"
Represents the d-axis and “q” represents the q-axis component.) Θ: Angle with respect to the stationary coordinate system

[0011] In contrast, the orthogonal voltage command v ^- is assumed to be given by the following equation. The orthogonal component is indicated by adding a “-” symbol to the shoulder of the code. v ⁻ = (sin θ, cos θ) v _r ^* (4) When this orthogonal voltage command v ⁻ is given to the same model as the AC network, a component i ⁻ orthogonal to i can be obtained. That is, it is obtained by calculating the following equation (5), which is obtained by replacing i in the above equation (1) with i ⁻ .

(Equation 2)

[0012] (5) is i derived from equation ^- by the the current detection value i in the following equation 3 (6), rotating coordinate system of the current vector _{i r "= (i d"} , i q " ) Convert to ^T.

(Equation 3)

The vector control means performs feedback control using the current vector. Therefore, the relationship between the input in the vector adjustment means, that is, the operation command r ^* , the feedback input u _f , the output v _r ^* , and θ is represented by a function h shown in the following equation (7). ^{_{(V r * T, θ)}} T = h (r * T, u f T) at ^T ... (7) Here, if you give as a feedback input u _f of the following formula (8),
i _r ″ can be fed back. u _f = i _r ″ (8) Since the current vector is an instantaneous value, even in the case of a single-phase power converter, it is possible to perform the control operation of the rotating coordinate system. Clearly, you can.

[0014] Next, in the above equation i ^- but the estimation of a course possible, if the estimated error of the state variable due the initial value or parameter errors are included, can not be accurately estimated.
Therefore, in order to suppress the error, it is possible to perform an estimation calculation provided with a feedback for suppressing the estimation error e. An arithmetic expression for estimating a state from the AC voltage command and the detected current value is represented by the following Expression (9).

(Equation 4)

[0015] i obtained above results ^- a By substituting the previous equation (6) can be obtained even more less current vector of the error. The above equation (9) is an operation equivalent to an observer or an adaptive observer, and its function does not change even if it is designed according to a generally known algorithm. The above is the case of N = 1. However, even in an N ≧ 2 N-phase power converter to which a symmetrical N (arbitrary integer) -phase AC network is connected, the expression (5) or (9) and (9) 6) Since the current vector is obtained according to the operation of the equation, one of the polyphases is obtained.
Even when a current detector is provided only for a phase, vector control can be performed as in the case of a single phase.

Next, the case of the third invention will be described. Since the current estimated value i 'in the above equation (9) converges to i by feedback of an error, the current vector can be controlled even if i' is used instead of i. So, first,
By replacing i in the equation (6) with i ′, (1)
The current vector estimated value i converted to the rotating coordinate system by the equation (0)
_r 'is obtained.

(Equation 5) The obtained current vector estimated value _ir 'is provided as a feedback input of the vector adjusting means instead of the current vector. That is, vector control is possible by using the following equation (11). u _f = _ir ′ (11) It is to be noted that the third invention is applicable to the N-phase power converter with N ≧ 1, as in the first and second inventions.

Next, the fourth and fifth aspects of the invention will be described. When the state equation of the AC network in the stationary coordinate system, that is, the equation (1) for polyphase, and the equations (1) and (5) for single phase, are transformed into the state equation of the rotating coordinate system, Equation (12) shown below.

(Equation 6)

Here, state variables and rotational coordinates of the stationary coordinate system
System state variable x_r"= (X_d", X _q”)^TBetween
There is a relationship as shown in Expression (13) of Expression (7).

(Equation 7)

Using the above relationship, the AC network model can be represented by the following equation (14) converted to a rotating coordinate system.

(Equation 8)

[0020] (14) is a state estimation is possible even while the expression, "there is a possibility that appears. Accordingly, the deviation e" initial value or parameter error due to estimation error e = i _r "-i _r '
Is fed back, the following equation (15) is obtained.

(Equation 9)

Next, the current vector calculation means, by substituting the current vector estimate i _r "obtained in the above equation in the following equation (16), perpendicular to current i ^-. The finding ⁱ - = ^{(sinθ cosθ)} i _r ″ (16) This is substituted into equation (6) to obtain a current vector i _r ′ = (i
_d ', _iq ') Calculate ^T. If this current vector is used, the N-phase power converter can be vector-controlled by detecting only one phase current, as in the first invention.

Next, the sixth invention will be described. In the fourth and fifth inventions, it has been shown that the current vector estimated value i _r ″ converges to the current vector i _r ′.
_By feeding back i _r ″ to the vector adjusting means instead of _r ′, it becomes possible to perform vector control of the N-phase power converter.

[0023]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention. This example includes a power converter 101, an AC network 102, a current detector 103, a vector adjusting unit 104, a state estimating unit 105, a first coordinate converting unit 106 for converting a voltage vector command into an AC voltage command, and an AC current detection value. Is converted into a current vector. The AC network 102 is the same as FIG. 8 or FIG. The state estimating unit 105 can be configured as an arithmetic unit that estimates a quadrature current orthogonal to the current detection value from the quadrature voltage command. Equation (5) is used for the estimation. Estimated quadrature current 11
3 is the second coordinate transformation means 10 together with the current detection value 112.
7 and the current vector 114 based on the equation (6).
Is converted to As the coordinate conversion means 107, a well-known means for performing an operation such as equation (6) can be used.

That is, despite the fact that only one current detector 103 is provided, the quadrature current is
5, an instantaneous value of the ripple-free current vector 114 associated with the fundamental wave can be obtained.
The vector adjusting means 104 calculates a voltage vector command from the current vector 114 and the operation command 108. FIG. 2 shows a specific example of the vector adjustment unit 104. That is, the current controller operation command 108 and the current vector 11
Adders / subtractors A1 and A2 for obtaining a deviation from the current controller 4 and current controllers R1 and R2 for calculating a voltage vector command 109 from the deviation.
2, and an integrator S that integrates the rotational angular velocity ω to obtain an angle 111 (θ: phase reference) between the rotating coordinate system and the stationary coordinate system.
Etc. It should be noted that a well-known means for performing calculations such as equations (2) and (4) can be used as the coordinate conversion means 106.

FIG. 3 shows a first modification of FIG. this is,
An AC voltage command output from the coordinate conversion means 106 and a current detection value via the current detector 103 are input to the state estimation means 105, and a quadrature current orthogonal to the current detection value is estimated by equation (9). The other features are the same as those in FIG. FIG. 4 is a configuration diagram showing a second modification of FIG. This example is almost the same in configuration as FIG. 3, but differs from FIG. 1 in that the detected current value is not input to the second coordinate conversion means 107. Here, the state estimating means 10
5 estimates the two-phase current estimation value 201 of the current detection value and the quadrature current by the equation (9). This estimated value is input to the second coordinate conversion means 107 and is converted into a current vector estimated value 202 based on the equation (10). Vector adjustment means 10
4 indicates the current vector estimated value 202 and the operation command 108
However, when the state estimating means 105 operates following the current detection value 112, the same vector control as in the case of FIG. 1 is realized.

FIG. 5 is a block diagram showing a second embodiment of the present invention. This example includes a power converter 101, an AC network 102, a current detector 103, and a vector adjustment unit 10.
4. It comprises a state estimating means 301, a first coordinate converting means 106 for converting a voltage vector command into an AC voltage command, a current vector calculating means 302, and the like. State estimation means 30
Reference numeral 1 designates an AC network 102
Is estimated based on equation (14). The estimated current vector estimation value 202 and the detected current value 112 are input to the current vector calculation means 302,
Here, the quadrature current i ⁻
Then, the calculation of Expression (6) is performed, whereby the current vector 114 is converted. By inputting this current vector to the vector adjusting means 104, vector control is performed.

FIG. 6 shows a modification of FIG. This is characterized in that the current detection value 112 is input to the state estimating means 301, and the current vector 202 of the AC network 102 is estimated based on the equation (15). The other points are the same as those in FIG.

FIG. 7 is a configuration diagram showing a third embodiment of the present invention. This example is characterized in that the current vector calculation means is omitted from the configuration shown in FIG. The state estimating means 401 receives the voltage vector command and the detected current value as inputs and estimates the current vector 202 of the AC network 102 based on the equation (15). This current vector estimation value 202 is used
, The vector control is performed.

When the AC voltage of the load or the power supply system or its phase, or the speed or phase information of the AC motor can be obtained in the AC network of each of the above examples, these are carried out by the vector calculating means and the state estimating means. Needless to say, it can be used for the calculation. Further, the state variables estimated as described above may be used for power converter control without any problem.

[0030]

According to the present invention, since the power converter is controlled by one current detector and a control algorithm, the number of current detectors is minimized to a minimum and unified by high-precision vector control. This provides the advantage of being able to be controlled. Also, the transfer function from the voltage vector command to the current vector or its estimated value is the same as in the case of multiple phases and multiple current detectors. Can be applied.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a specific example of a vector adjusting unit of FIG. 1;

FIG. 3 is a configuration diagram showing a first modification of FIG. 1;

FIG. 4 is a configuration diagram showing a second modification of FIG. 1;

FIG. 5 is a configuration diagram showing a second embodiment of the present invention.

FIG. 6 is a configuration diagram showing a modification of FIG. 5;

FIG. 7 is a configuration diagram showing a third embodiment of the present invention.

FIG. 8 is a configuration diagram showing a first conventional example.

9 is a configuration diagram illustrating a specific example of the AC circuit network of FIG. 8;

FIG. 10 is a configuration diagram showing a second conventional example.

11 is a configuration diagram showing a specific example of the AC circuit network of FIG. 10;

[Explanation of symbols]

101, 503: power converter, 102: AC circuit network, 1
03, 701: current detector, 104: vector adjustment means, 105, 301, 401 ... state estimation means, 106,
107: coordinate conversion means, 108: operation command, 109: voltage vector command, 110: AC voltage command, 111: phase reference, 112: current detection value, 113: quadrature current estimation value,
114 ... current vector, 115 ... orthogonal voltage command, 201
... two-phase current estimated value, 202 ... current vector estimated value, 30
2. Current vector calculation means, 501: AC command generation means, 502: current adjustment means, 601, 801: power supply system or load, 602, 802: filter, 803: AC motor.

Claims (6)

[Claims] 1. A current detector provided only in one phase of a power converter having an N (arbitrary integer) phase AC side terminal, a vector adjuster for calculating a voltage vector command of a rotating coordinate system, First coordinate conversion means for converting a vector command into an orthogonal component (orthogonal voltage command) corresponding to the AC voltage command and the AC voltage command of the current detection phase, and a component (orthogonal current) orthogonal to the current detection value from the orthogonal voltage command ), And second coordinate conversion means for calculating a current vector from the estimated quadrature current and the detected current value, and a voltage based on an output from the second coordinate conversion means and an operation command. And a power converter control method characterized in that current vector control is enabled. 2. The estimation means includes a quadrature voltage command,
The power converter control method according to claim 1, wherein the AC voltage command and the current detection value are input. 3. A current detector provided only in one phase of a power converter having an N (arbitrary integer) -phase AC side terminal, a voltage vector command of a rotating coordinate system and a command for a rotating coordinate system and a stationary coordinate system. A vector adjuster for calculating a phase difference; first coordinate conversion means for converting the voltage vector command into an orthogonal component (orthogonal voltage command) corresponding to an AC voltage command and an AC voltage command for a current detection phase; ., Estimating means for estimating a two-phase current of a current detection value and the quadrature current value from the AC voltage command and the quadrature voltage command, and second coordinate converting means for converting the two-phase current into a current vector. A power converter control method, wherein voltage and current vectors can be controlled based on an output from the second coordinate conversion means and an operation command. 4. A current detector provided only in one phase of a power converter having an N (arbitrary integer) phase AC side terminal, a voltage vector command of a rotating coordinate system, and a current detector for a rotating coordinate system and a stationary coordinate system. A vector adjuster for calculating a phase difference, and coordinate conversion means for converting the voltage vector command into an AC voltage command,
Estimating means for obtaining an estimated current vector value from the voltage vector command, the phase difference and the current vector; and current vector calculating means for calculating a current vector from the estimated current vector value and the detected current value. A power converter control system characterized in that voltage and current vectors can be controlled based on an output from the means and an operation command. 5. The power converter control method according to claim 4, wherein a current detection value is also input to said estimating means. 6. A current detector provided in only one phase of a power converter having an N (arbitrary integer) phase AC side terminal, a voltage vector command of a rotating coordinate system, and a command for a rotating coordinate system and a stationary coordinate system. A vector adjuster for calculating a phase difference, and coordinate conversion means for converting the voltage vector command into an AC voltage command,
Estimating means for obtaining an estimated current vector value from the detected current value, the phase difference, and the voltage vector command, and controlling the voltage and the current vector based on the output from the estimating means and the operation command. Power converter control method.