JP2774246B2 - Control device for current source 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 controller for a polyphase current source converter used as a DC source or a control source.

[0002]

2. Description of the Related Art In many cases, a conventional multi-phase current source converter control method is based on a PWM pattern synthesizing method of synthesizing a PWM pattern and controlling a converter bridge. This pattern synthesis is created in a so-called open loop, ignoring the dynamic characteristics of the system. Further, when controlling the output current of the multi-phase current source converter, a DC current control loop is provided to detect and control the output current of the converter.

That is, as shown in FIG. 7, a DC current flowing through a load 12 is detected to determine a deviation from a current command value.
A voltage command is obtained by the current controller 8, and the voltage command is given to the converter unit 10. The control unit 9 of the converter unit 10 performs pattern synthesis based on the given voltage command, and achieves the control purpose by controlling the average value of the output voltage of the converter bridge 11 to be a value close to the voltage command. I have.

[0004]

However, in the control method described above, the voltage command value is obtained from the deviation between the current command and the load current, and the converter unit 10 is operated based on the obtained voltage command.
, The stability of the current control loop deteriorates due to the delay of the output voltage control of the converter, and the response performance has to be limited to a low level.

Further, since the converter output voltage control is performed ignoring the dynamic characteristics of the system, there is a possibility that the stability of the voltage control unit itself may be lost due to the influence of the load operation state. SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems of the related art, and an object of the present invention is to control the converter by taking into account the dynamic characteristics of the converter using sliding mode control theory, and to perform switching of the converter. A control device for a multi-phase current source converter that can directly control the load current instantaneously by using the operation directly to control the load current, and can also match the power supply phase angle (power factor) to a required value. It is to provide.

[0006]

FIG. 1 is a diagram illustrating the principle of the present invention. In the figure, 1 is a first for calculating a voltage vector.
And calculates a voltage vector that can be used for control at that time from the instantaneous value of the power supply voltage and the operable switch state. The effective component of the voltage vector is the input that controls the DC current,
The invalid component is defined as an input for controlling the phase angle.

Reference numeral 2 denotes a second means for calculating an average value of the effective component and the invalid component of the voltage vector, and obtains an average value of the selected voltage vector. The average value is proportional to the dq component of the current flowing from the power supply, and has the effect of estimating the power supply current. The effective component of the average also has the effect of estimating the load voltage. 3 is a third means for extracting a vector that converges the DC current control deviation from the voltage vector,
Reference numeral 4 denotes fourth means for obtaining a voltage vector invalid component command value from the power supply phase angle command value, and reference numeral 5 denotes fifth means for extracting a voltage vector that converges the phase angle control deviation.

Reference numeral 6 denotes sixth means for selecting a vector for converging both the current control deviation and the phase angle deviation, and outputting the corresponding semiconductor switching signal to the multi-phase current source converter load system 7. Thus, a desired control purpose can be achieved. To solve the above problem, as shown in FIG.
According to a first aspect of the present invention, there is provided a control device for a multi-phase current source converter that matches an output current of a converter that obtains DC from multi-phase AC with a command value and matches a phase angle of the power with a required value. A first means for calculating a voltage vector determined by a voltage instantaneous value and a switch state; and a second means for obtaining an average value of an effective component and an invalid component of the selected voltage vector.
The effective component and the load voltage value are compared between the means 2 and the voltage vector calculated by the first means 1, and the polarity of the difference matches the polarity of the difference between the output current command value and the DC current value. And a fourth means 4 for obtaining a command value of the voltage vector from the phase angle command value and the average value of the effective components of the voltage vector obtained by the second means 2. The polarity of the difference between the invalid component of the voltage vector and the command value of the invalid component of the voltage vector obtained by the fourth means 4,
Fifth means 5 for generating an output when the polarity of the difference between the invalid component command value and the average value of the invalid components of the voltage vectors obtained by the second means 2 matches each other; Means 5
And a sixth means 6 for selecting a voltage vector that generates an output together, and configured to obtain an open / close command for a semiconductor switch constituting a polyphase converter based on the voltage vector obtained by the sixth means 6. It is.

According to a second aspect of the present invention, in the first aspect of the invention, the tangent value of the command value of the power supply phase angle is multiplied by the average value of the effective component of the voltage vector obtained by the second means 2. And a fourth means 4 for obtaining an invalid component command value of the voltage vector. The invention of claim 3 of the present invention provides:
According to the first aspect of the present invention, the fourth means 4 is replaced with a means for multiplying a tangent value of a power supply phase angle command value by a load voltage value to obtain an invalid component command value of a voltage vector.

The invention according to claim 4 of the present invention relates to claims 1 and 2
Alternatively, in the invention according to claim 3, the third means 3 is replaced by the first means.
The voltage vector calculated by the means 1 is compared with its effective component and the average value of the effective components of the voltage vector obtained by the second means 2, and the polarity of the difference and the difference between the output current command value and the DC current value are compared. Are replaced by a means for generating an output when the polarities of.

The invention according to claim 5 of the present invention is directed to claim 1,
In the invention according to the second or third aspect, the fifth means 5
Is compared with the voltage vector calculated by the first means 1 and the average value of the invalid component of the voltage vector obtained by the second means 2, and the polarity of the difference, the invalid component command value and the This means is replaced by a means for generating an output when the polarity of the difference between the average values of the invalid components of the voltage vector obtained by the second means 2 matches.

[0012]

In order to achieve the above object, the dynamics of the converter system is analyzed to determine a control method. Here, for the sake of simplicity, a case of a three-phase AC power supply will be described below. If the LC low-pass filter for preventing the flow of the switching harmonic to the power supply and the snubber circuit for suppressing the surge voltage are omitted, the main circuit configuration of the three-phase current source converter can be shown as in FIG.

[0013] The power supply voltage Vs = [V _s1, V _s2, V _s3] ^T
And the power supply current is _s = [ _is1 , _is2 , _is3 ] ^T , and the DC reactor current (hereinafter referred to as DC output current) is i
In _L, and the output load direct voltage denoted by V _0, the dynamic properties of the system can be expressed as the following (1) to (4) below.

[0014]

(Equation 1)

Here, V _g is the maximum value of the power supply phase voltage, ω is the power supply frequency, and t is a variable representing time. Also,
u = [u ₁ , u ₂ , u ₃ ] ^T is a switching function,
It is defined as in equation (5).

[0016]

(Equation 2)

Vα (α is a suffix of V, the same applies hereinafter) is an input for adjusting the load current with the converter output voltage. Here, a voltage Vβ (β is a suffix of V, the same applies hereinafter) is newly defined as in equation (6), and Vα and Vβ are defined as an effective component and an invalid component, respectively, and a voltage vector [Vα, Vβ] ^T
(The means for forming the voltage vector [Vα, Vβ] ^T corresponds to the first means 1 in the present invention).

[0018] V? = (1 / √3) _{[(V s3 -V s2) u 1} + (V s1 -V s3) u 2 + (V s2 -V s1) u 3 ] (6) a three-phase, Seven types of switch states operable on the circuit are available, and correspondingly, a voltage vector usable for control can be calculated from the instantaneous value of the power supply voltage as shown in the table of FIG.

Conventionally, the power supply phase angle is based on a power supply voltage and a power supply current vector [ _isd , on a rotating coordinate (dq coordinate)].
i _sq ] ^T is evaluated based on the relative relationship, and the vector is as shown in Equations (2) to (7). Here, when the voltage vector is expressed as a function of time, it is as shown in equation (8), and (7)
Comparing the equation with the equation (8), the voltage vector [Vα, V
It can be seen that β] ^T is proportional to [ _isd , _isq ] ^T.

[0020]

(Equation 3)

[0021] Thus, the phase angle can be evaluated in a relative relationship between [i _sd, i _sq] instead of ^T [V.alpha, V?] ^T. However, since the voltage vector ones discontinuous, it is necessary to evaluate by the average value _[ave V.alpha, _ave V?] ^T. Then, the average value is filtered by a filter such as the following (9)
It is assumed that the signal passes through a first-order low-pass filter as shown in the equation.
(The means for calculating the average value corresponds to the second means 2 for calculating the average value in the present invention).

[0022]

(Equation 4)

If the power supply phase angle is φ ^* angle, the command value to follow the average value of the invalid component of the voltage vector is (10)
It is determined as in the equation. Vβ ^* = tan (φ ^* ) · _ave Vα (10) The means for obtaining the command value of the voltage vector invalid component as described above corresponds to the fourth means 4 in the present invention.

Therefore, the command value of the DC reactor current is i
_{When L} ^* and the phase angle command value are φ ^* , the control target is determined to converge the control deviations e _i = i _L ^* −i _L , eφ = Vβ ^* _−ave Vβ to zero. When φ ^* = 0,
The power factor is 1. Here, φ in eφ indicates a subscript of e, and _ave Vβ indicates an average value of Vβ. In addition, the DC reactor current command value i _L ^* is hereinafter referred to as a DC current command value.

In order to achieve the above control purpose, a control voltage vector is selected. The selecting means is as follows. sign (Vα−V ₀ ) = sign (e _i ) (11) sign (Vβ−Vβ ^* ) = sign (eφ) (12) That is, in the voltage vector, the effective component Vα is the polarity condition of the equation (11). Means for selecting a voltage vector such that the invalid component Vβ satisfies the polarity condition of (12). The means for determining the polarity condition of the above equation (11) corresponds to the third means 3 of the present invention, and (12) The means for determining the polarity condition of the expression corresponds to the fifth means 5, and the third and fifth means 5
The output means corresponds to the sixth means 6, which selects the voltage vector when both output the signals and outputs the corresponding semiconductor switch signal.

In this case, it is guaranteed that e _i and eφ converge to zero. To confirm this, first, the deviation e
A Lyapunov function candidate for _i is selected as shown in (13). V _i = (１ ／) Le _i ² (13) Differentiate both sides to obtain a relation of di _L ^* / dt = 0, (3)
(4) By substituting (11), an inequality is established as in equation (14), and the deviation converges to zero according to Lyapunov stability theory.

DV _i / dt = Le _i (de _i / dt) = − e _i · L (di _L / dt) = − e _i (Vα−V ₀ ) = − e _i | Vα−V ₀ | · sign (Vα−V ₀ ) = − e _i | Vα−V ₀ | · sign (e _i ) = − | e _i | · | Vα−V ₀ | ≦ 0 (14) Next, a candidate Lyapunov function for the deviation eφ is (15)
Choose like.

Vφ = (１ ／) τeφ ² (15) Differentiating both sides and substituting the equations (9) and (12) gives
An inequality like (16) holds. dVφ / dt = τeφ (deφ / dt) = eφ · τ (deφ / dt) = − eφ [−eφ− (Vβ−Vβ ^* )) = − eφ ² − | eφ | · sign (eφ) | Vβ−Vβ ^* | Sign (Vβ−Vβ ^* ) = − eφ ² − | eφ | · | Vβ−Vβ ^* | ≦ −eφ ² (16) According to Lyapunov's stability theory, eφ converges to zero.

As described above, if the vectors are selected by the third, fifth, and sixth means 3, 5, 6, it is understood that both the DC current control deviation and the phase angle control deviation converge in the direction of zero. In the above control means, the instantaneous value of the load voltage is used, but in the low frequency region, the average value of the load current is almost constant.
Since the differential value becomes almost zero, it can be understood that there is a relationship of _ave Vα = V _{0 by} taking the average value of both sides of the equation (3).
Therefore, no problem even substitute load voltage value of said third means 3 by the average value _ave V.alpha the effective value of the voltage Bekuruto.

Conversely, the fourth means 4 was used to calculate Vβ ^* .
_ave Vα may be replaced with a load voltage. Although Vβ−Vβ ^* was compared with the polarity condition (12) in the fifth means 5, the convergence is similarly guaranteed in the comparison of Vβ− _ave Vβ. As described above, the objects of DC current control and phase angle control are achieved by the first to sixth control means.

In the first to fifth aspects of the present invention, since the polyphase current source converter is controlled based on the above principle, the load current can be directly instantaneously controlled and the power supply phase angle can be specified. Can be adjusted as per.

[0032]

FIG. 4 shows the configuration of a control device according to an embodiment of the present invention.
13 is a polyphase AC power supply, 11 is a polyphase current source
Converter, 14 is a DC reactor, C is a capacitor, 1
2 'is a load. 21 is the detected power supply voltage V
_S, DC reactor current i_L, Load voltage V ₀The digital
A / D converter for converting into a signal, 22 is an A / D converter
The converted digital signal is processed by the method described above.
Digital signal processor, 23 is a multiphase current type
A gate drive circuit for controlling the gate of the inverter 11.
You.

FIGS. 5 and 6 are flow charts showing the processing in the digital signal processor 22 shown in FIG. 4. FIG. 5 shows a flow chart from the input of the input signal to the output of the open / close signal of the converter. By repeating the processing shown in the figure,
The polyphase AC converter is controlled. Next, this embodiment will be described with reference to FIGS.

First, the digital signal processor 22
Is the DC current command value i _L ^* in step S1 of FIG.
The phase angle command value φ ^* is read, and in step S2, the DC output current i _L , the load DC voltage value V ₀ , and the power supply voltage V _S are read. Then, in step S3, an invalid component command value Vβ ^* is obtained from the above-described equation (10).

Note that _ave Vα in the equation (10) is the effective component average value of the voltage vector calculated in advance in the previous process (step S10 described later). In step S4, the polarity of the difference between the DC current command value i _L ^* and the DC output current i _L and the polarity of the difference between the invalid component command value Vβ ^* and the average value _ave Vβ of the voltage vector invalid component are obtained.

The _ave Vβ is the same as _ave Vα.
This is the average value of the invalid component of the voltage vector calculated in advance in the previous process (step S10 described later). Next, a voltage vector selection process is performed as follows. That is, when the number of operable switch states is n, the polarity is determined for 1 to n as follows.

First, in step S5, the switch state number m = 1 (m ≦ n: n = 7 in the case of three-phase, m corresponds to the mode number in FIG. 3), and step S5 in FIG.
In step 6, the m-th voltage vector [V ^m α, V ^m β] ^T is calculated. In step S8, the polarities sign (e _i ), sign (eφ), and sign (V ^m ) of the deviation obtained in step S4
α−V ₀ ) and sign (V ^m β−Vβ ^* ).
If they do not match, m = m in step S7.
Returning to step S6 as +1 repeats the above processing.

When the polarities match in step S8,
Go to step S9, output the signal [u ₁ ^m , u ₂ ^m , u ₃ ^m ] of the m-th switch state number whose polarity matches,
alpha, V?] = [V ^m alpha, and V ^m beta]. Then, in step S10, the above Vα and Vβ are passed through a low-pass filter to obtain a vector average value of the effective component and the invalid component of the voltage vector.

[U ₁ ^m ,
u ₂ ^m , u ₃ ^m ] are output to the gate drive circuit 23 shown in FIG. 4, and the switching circuit of the multiphase current type converter 11 is controlled to open and close. Further, as described above, in step S8, no problem even substitute load voltage value V ₀ by the average value _ave V.alpha the effective value of the voltage Bekuruto.

Further, it may be replaced with _ave V.alpha using the V? ^* Of calculation in the step S3 in load voltage value V _0. Further, in step S8, V ^m β−Vβ ^*
Was compared, convergence in comparison V ^m β- _ave Vβ is guaranteed in the same way.

[0041]

As described above, according to the present invention,
The following effects can be obtained. The load current can be directly instantaneously controlled, and the power supply phase angle can be adjusted as specified. Without using the load parameter information, the control performance is guaranteed even if the load parameter fluctuates or the load changes, and has a so-called strong robustness. Since only the instantaneous voltage value is required for the power supply and no prior information such as the maximum value of the power supply voltage and frequency is required,
Even if the converter is connected to a different power source, it can be operated without changing the control. The flow of control is simple, and the polarity judgment, addition and subtraction,
Since there is nothing other than multiplication and no coordinate conversion or the like conventionally required is required, programming and control circuits can be simplified. Since there is a function of estimating the power supply current, unlike the conventional control method, the power supply phase angle can be controlled without a power supply current sensor.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a diagram showing a main circuit configuration of a three-phase current source converter.

FIG. 3 is a diagram showing seven types of switch states operable on a circuit in the case of three phases.

FIG. 4 is a diagram illustrating a configuration of a control device according to an embodiment of the present invention.

FIG. 5 is a flowchart illustrating a process according to the embodiment of the present invention.

FIG. 6 is a flowchart (continued) showing a process in the embodiment of the present invention.

FIG. 7 is a diagram showing a conventional example.

[Explanation of symbols]

1 first means for forming a voltage vector 2 second means for obtaining an average value of the voltage vector 3 third means for determining whether the polarity of the difference between the effective component of the voltage vector and the load voltage matches the current control deviation 4 A fourth means for obtaining a command value of a voltage vector invalid component from a power supply phase angle command value 5 A means for determining whether the polarity of the difference between the voltage vector invalid component and the invalid component command value matches the polarity of the phase angle control deviation 6 When both the third and fifth means 3 and 5 are determined to be the same, the sixth means for outputting a semiconductor switching signal corresponding to the voltage vector 7 The controlled polyphase current source converter load system 8 Conventional example Load current controller 9 conventional voltage pattern synthesizing device 10 conventional output voltage control system 11, 11 ′ multi-phase current source converter bridge 12, 12 ′ driven load 13 multi-phase AC power supply 14 Flow reactor 21 A / D converter 22 a digital signal processor 23 the gate drive circuit V _s polyphase AC power supply voltage i _s polyphase AC supply current ω power supply angular frequency i _L DC reactor current V ₀ load voltage V _g multiphase AC power source Maximum value of voltage u Switching function indicating the switch state L Inductance of DC reactor t Time function Vα Effective component of voltage vector Vβ Invalid component of voltage vector Vβ ^* Inactive component command value of voltage vector i _sd Power supply current on d-q coordinate the reactive component _ave V.alpha voltage average value _ave V? time constant phi phase angle phi ^* phase angle of the mean value τ lowpass filter reactive component of the voltage vector of the effective component of the vector of the power supply current on the effective component i _sq d-q coordinates of Command value i _L ^* Command value of DC reactor current e _i Control deviation of DC current eφ Control deviation of phase angle V _i Regarding DC current deviation Lyapunov function candidate V _e φ Lyapunov function candidate for phase angle deviation sign Sign function

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-310375 (JP, A) JP-A-5-122940 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02M 7/00-7/98

Claims (5)

(57) [Claims] 1. A control device for a multi-phase current source converter for matching an output current of a converter for obtaining a direct current from a multi-phase alternating current with a command value and matching a phase angle of a power supply current with a required value. A first means for calculating a voltage vector determined by a switch state; a second means for obtaining an average value of an effective component and an invalid component of the selected voltage vector; and a second means for calculating a voltage vector calculated by the first means. A third means for comparing the effective component with the load voltage value, and generating an output when the polarity of the difference and the polarity of the difference between the output current command value and the DC current value match; A fourth means for obtaining a command value of an invalid component of the voltage vector from the average value of the effective components of the voltage vector obtained by the second means; and an invalidity of the voltage vector obtained by the invalid component of the voltage vector and the fourth means. Success The fifth means for generating an output when the polarity of the difference between the command values of the above and the invalid component command value and the polarity of the difference between the average values of the invalid components of the voltage vector obtained by the second means match; Means and a fifth means, both of which include a sixth means for selecting a voltage vector for generating an output, and obtaining an open / close command for a semiconductor switch constituting a polyphase converter based on the voltage vector obtained by the sixth means. A control device for a current source converter that obtains a direct current from a polyphase alternating current. A fourth means for multiplying the tangent value of the command value of the power supply phase angle by the average value of the effective component of the voltage vector obtained by the second means to obtain a command value of an invalid component of the voltage vector; 2. The control device for a current source converter according to claim 1, wherein said converter obtains a direct current from the polyphase alternating current. 3. The apparatus according to claim 1, wherein said fourth means is replaced by means for multiplying a tangent value of a power supply phase angle command value and a load voltage value to obtain an invalid component command value of a voltage vector. Control device for current source converter that obtains DC from multi-phase AC. 4. The third means compares the effective component of the voltage vector calculated by the first means with the mean value of the effective component of the voltage vector obtained by the second means, and calculates the polarity of the difference. 4. A current source converter for obtaining a direct current from a multi-phase alternating current according to claim 1, 2 or 3, wherein the output is replaced by means for generating an output when the polarity of the difference between the output current command value and the direct current value matches. Control device. 5. A fifth means for comparing the voltage vector calculated by the first means with the average value of the invalid component of the voltage vector obtained by the second means and the polarity of the difference. And means for generating an output when the polarity of the difference between the average value of the invalid component of the voltage vector and the invalid component command value obtained by the second means matches.
A control device for a current source converter for obtaining a direct current from a polyphase alternating current according to claim 3 or 4.