JP2005073334A - Controller for ac-ac direct conversion type power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow operation of a converter by generating an appropriate input current instruction, even if a power converter is connected by mistake to provide a different phase sequence of an input voltage. <P>SOLUTION: A controller which is a direct converter, such as matrix converter, comprises a phase sequence determining means for an input voltage and an input current instruction generating means which generates an input current instruction for each phase to provide the same phase sequence with a determined one. The phase sequence determining means comprises a means 10 for converting a three-phase input voltage into biphasic quantity of orthogonal biaxial coordinate system, and a means 11 for acquiring the angle of an input voltage vector composed of the biphasic quantity. A three-phase oscillator 6, acting as an input current instruction generating means, generates the input current instruction of each phase using the angle of the input voltage vector. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides an AC-AC direct conversion type that directly converts a polyphase AC voltage into a polyphase AC voltage having an arbitrary magnitude and frequency using a semiconductor switching element without using a large energy buffer such as a capacitor. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a power converter (hereinafter also referred to simply as a direct converter), and particularly relates to a technique for generating an input current command that controls the input current waveform of the converter in consideration of the phase sequence of the input voltage. It is.

  An AC switch (bidirectional switch) is configured by at least two unidirectional semiconductor switching elements capable of controlling a unidirectional current so that a three-phase AC voltage having an arbitrary magnitude and frequency is directly obtained from the three-phase AC voltage. As the direct converter, a matrix converter will be described as an example.

FIG. 10 shows the prior art of the matrix converter and its control device.
In the figure, 1 is a three-phase AC power source, 2 is a matrix converter, 3 is a load such as an AC motor, 12 is a transformer, 4 is a voltage polarity discriminating means, 5 is a PLL circuit, 6 is a three-phase oscillator, and 9 is an input voltage. Size detection means, 7 is an output voltage command generation means, 8 is a pulse generation means, R, S, T are AC input terminals, U, V, W are AC output terminals, S _ur , S _ru , S in the matrix converter 2 _us , S _su , S _ut , S _tu are unidirectional switching elements.

  In the matrix converter 2 shown in FIG. 10, an AC switch connected between the R, S, T phase of the input phase and the U phase of the output phase (each composed of two unidirectional switching elements connected in the reverse direction). The AC switch connected between the R, S, and T phases of the input phase and the V and W phases of the other output phases has the same connection configuration, and the three-phase AC power source 1 A total of nine AC switches are connected between the load and the load 3.

In the configuration of FIG. 10, the matrix converter 2 cuts out a three-phase AC voltage by nine AC switches that are PWM-controlled, obtains a three-phase AC voltage having an arbitrary magnitude and frequency, and supplies it to the load 3.
Here, the input current command of the matrix converter 2 is generated as follows. That is, the polarity of one phase of the input voltage passed through the transformer 12 is detected by the voltage polarity discriminating means 4, and a pulse synchronized with the input voltage is generated. This pulse is input to the PLL circuit 5 to detect the phase of the input voltage, and this voltage phase is used as angle data, and an input current command is generated using the three-phase oscillator 6.

On the other hand, the input voltage magnitude detection means 9 discriminates the magnitude relation (maximum input voltage and minimum input voltage) of the phase input voltages v _R , v _S , v _T , for example, X (X is R, S, Any of T) When the phase is the maximum, X _p = 1 (X _p = 0 for the other phase), and when the X phase is the minimum, X _n = 1 (X _n = 0 for the other phase) The magnitude relationship between the phase input voltages v _R , v _S , and v _T is determined, and “1” and “0” of X _p and X _n (R _p , R _n , _Sp , _Sn , T _p , T _n ) are determined. The combination of is output.

  The pulse generation means 8 is based on the input current command from the three-phase oscillator 6, the magnitude relationship between the input voltages from the input voltage magnitude detection means 9, and the output voltage command generated by the output voltage command generation means 7. The PWM command to be given to each unidirectional switching element of the matrix converter 2 is calculated, the matrix converter 2 is controlled by the output pulse, and the input current and the output voltage are controlled according to each command.

Here, since the input current command is generated based on the input voltage phase detected by the PLL circuit 5, the phase order of the input voltage is important for the control.
A detection method when the phase order of the input voltages is reversed is disclosed in, for example, Patent Document 1 described later. The invention described in Patent Document 1 relates to a power supply voltage abnormality detection circuit and method capable of detecting both abnormalities in a state where only one phase of the power supply voltage is lost and a state where the phase sequence is reversed. The outline is as follows.

That is, the power supply voltage information generating circuit, the three-phase AC power supply R, S, and detects the information corresponding to the magnitude relationship between the voltage value of each phase of T is output as the power supply voltage information signal R _max through T _min. The abnormality detection signal generation circuit holds in advance information based on the magnitude relationship of the voltage values of the R, S, and T phases when the three-phase AC power supply is normal, and this information is used as the abnormality detection signal R. and outputs it as the _max ^* ~T _min ^*. If the determination circuit, a power supply voltage information signal _R max _{through T min} and abnormality detection signal _R ^{max *} _{~T min} * compared at regular intervals, which is open-phase only (e.g. one phase of these signals are different When the phase sequence is reversed, the power supply voltage abnormality signal is output.

JP 2001-258151 A (Claim 1, FIG. 2, etc.)

If the connection of the devices is wrong and the phase sequence of the input voltage is different, the actual phase sequence between the input current command and the input voltage of the matrix converter 2 will be different. May occur, destroying the switching element or destroying the load 3. Further, when the power converter is stopped by outputting a power supply voltage abnormality signal or outputting an overcurrent protection signal by means disclosed in Patent Document 1, the operation itself is impossible.
In addition, in the phase sequence determination means disclosed in Patent Document 1, in order to determine the phase sequence, the magnitude relationship of the voltage values of the R, S, and T phases when the three-phase AC power supply is normal is determined. Since it is necessary to hold the information based on it in advance, there is a problem that the configuration becomes complicated and the cost of the control device increases.

  Therefore, the present invention does not need to hold in advance information or the like based on the magnitude relationship of each phase voltage value when the three-phase AC power supply is normal, and includes a phase sequence determination unit having a relatively simple configuration, and a power converter Therefore, the present invention intends to provide a control device for a direct converter that enables operation of the power converter even when the phase order of the input voltages is different due to a wrong connection.

In order to solve the above problem, the invention described in claim 1
The AC switch group configured to form an AC switch group by providing a plurality of bidirectional AC switches composed of at least two unidirectional semiconductor switching elements capable of controlling a unidirectional current, and connected to each phase of a three-phase AC power source A control device for an AC-AC direct conversion power converter that directly converts a three-phase AC voltage into a three-phase AC voltage having an arbitrary magnitude and frequency,
A phase sequence determination unit that determines a phase sequence of the input voltage of the power converter, and an input current command for each phase of the power converter so that the phase sequence is the same as the phase sequence determined by the phase sequence determination unit. An input current command generating means for generating,
The phase order determination means includes means for converting a three-phase input voltage into a two-phase quantity in an orthogonal two-axis coordinate system, and means for obtaining an angle of an input voltage vector composed of the two-phase quantity,
The input current command generation means generates an input current command for each phase using the angle of the input voltage vector.

The invention described in claim 2
The AC switch group configured to form an AC switch group by providing a plurality of bidirectional AC switches composed of at least two unidirectional semiconductor switching elements capable of controlling a unidirectional current, and connected to each phase of a three-phase AC power source A control device for an AC-AC direct conversion power converter that directly converts a three-phase AC voltage into a three-phase AC voltage having an arbitrary magnitude and frequency,
A phase sequence determination unit that determines a phase sequence of the input voltage of the power converter, and an input current command for each phase of the power converter so that the phase sequence is the same as the phase sequence determined by the phase sequence determination unit. An input current command generating means for generating,
The phase order determining means comprises means for converting a three-phase input voltage into a two-phase quantity in an orthogonal two-axis coordinate system, and means for judging the phase order from the phase difference between the two-phase quantities,
The input current command generating means generates an angle with polarity based on the phase order determined by the phase and the phase order determined by the phase and the phase order determining means, and means for detecting the phase of the input voltage from the polarity of the input voltage of a certain phase. And means for generating an input current command for each phase using this angle.

The invention described in claim 3
The AC switch group configured to form an AC switch group by providing a plurality of bidirectional AC switches composed of at least two unidirectional semiconductor switching elements capable of controlling a unidirectional current, and connected to each phase of a three-phase AC power source A control device for an AC-AC direct conversion power converter that directly converts a three-phase AC voltage into a three-phase AC voltage having an arbitrary magnitude and frequency,
A phase sequence determination unit that determines a phase sequence of the input voltage of the power converter, and an input current command for each phase of the power converter so that the phase sequence is the same as the phase sequence determined by the phase sequence determination unit. An input current command generating means for generating,
The phase order determining means includes means for determining a phase order from a phase difference corresponding to a magnitude relationship of three-phase input voltages,
The input current command generating means generates an angle with polarity based on the phase order determined by the phase and the phase order determined by the phase and the phase order determining means, and means for detecting the phase of the input voltage from the polarity of the input voltage of a certain phase. And means for generating an input current command for each phase using this angle.

  According to the present invention, in a direct converter such as a matrix converter, an appropriate input current command can be generated and the converter can be operated even when the phase sequence of the input voltage is wrong. Thereby, when installing a power converter, it becomes possible to connect similarly to the conventional inverter etc., without paying special attention about a phase order. In addition, since a complicated calculation or circuit is not required when determining the phase order, an inexpensive control device can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 is a block diagram of a first embodiment of the present invention corresponding to claim 1. The same components as those of FIG. 10 are denoted by the same reference numerals, and detailed description thereof will be omitted. The description will focus on the parts different from 10.

In FIG. 1, a three-phase / two-phase conversion unit 10 and an angle calculation unit 11 as phase order determination units are used instead of the voltage polarity determination unit 4 and the PLL circuit 5 in FIG. Between the side and the three-phase oscillator 6, a three-phase / two-phase conversion means 10 and an angle calculation means 11 are sequentially connected. The angle calculation means 11 and the three-phase oscillator 6 constitute input current command generation means.
The reason why the input current command according to the phase order of the input voltage can be generated by the above configuration will be described below.

The three-phase / two-phase conversion means 10 converts the three-phase input voltage into two of the orthogonal two-axis coordinate system by the calculation of Equation 1, where the phase input voltages via the transformer 12 are v _R , v _S , and v _T. The phase quantities v _α and v _β are converted.

When the input voltage is a three-phase symmetric sine wave, the output voltages v _α and v _β of the three-phase / two-phase conversion means 10 are sine waves having different phases by 90 °. In the case where the input voltage is expressed as a vector with v _α as the horizontal axis and v _β as the vertical axis, the angle θ _S is obtained by Equation 2.

2 shows the behavior of the input voltage vector when the phase order of the power supply voltage is R → S → T, and FIG. 3 shows the behavior of the input voltage vector when the phase order is R → T → S.
If phase sequence as shown in Figure 2 is R → S → T, v is v _beta against _α becomes delayed 90 ° in phase, the input voltage vector rotates counterclockwise. On the other hand, as shown in FIG. 3, when the phase order is R → T → S, v _β advances to 90 ° with respect to v _α , and the input voltage vector rotates clockwise. Therefore, if the input current command is generated based on the angle θ _S of the input voltage vector, an input current command having the same phase sequence as the input voltage phase sequence can be obtained.
Specifically, in FIG. 1, the angle calculation means 11 obtains the angle θ _S of the input voltage vector from the output voltages v _α and v _β of the three-phase / two-phase conversion means 10 according to Equation 2, and the three-phase oscillator 6 generating an input current command using the angle theta _S.

Next, FIG. 4 is a block diagram of a second embodiment of the present invention corresponding to claim 2.
In the first embodiment described above, the angle θ _S of the input voltage vector is calculated by Equation 2. However, the calculation of tan ⁻¹ in Equation 2 is a heavy load on the CPU that constitutes the angle calculation means 11, and an expensive CPU may be required. Therefore, in the second embodiment, the phase order of the input voltage is determined without performing the calculation of tan ⁻¹ .

That is, in the second embodiment of FIG. 4, the three-phase / two-phase conversion means 10 and the positive / negative determination means 21 sequentially connected to the secondary side of the transformer 12 are added to the configuration of the prior art of FIG. Multiplication means 13 is provided to correct the output of the PLL circuit 5 (input voltage phase as angle data) based on the determination output of the positive / negative determination means 21. Here, the three-phase / two-phase conversion means 10 and the positive / negative determination means 21 constitute a phase order determination means.
That is, in the second embodiment, the phase order is determined from the polarities (phase differences) of the two-phase quantities v _α and v _β obtained by converting the three-phase input voltage into the orthogonal two-axis coordinate system.

FIG. 5 shows the operation of this embodiment when the phase sequence of the power supply voltage is R → S → T, and FIG. 6 shows the operation of this embodiment when the phase sequence is R → T → S.
The positive / negative determining means 21 in FIG. 4 determines the positive / negative (polarity) of the two-phase voltages v _α and v _β output from the three-phase / two-phase converting means 10 and generates a pulse that is 90 ° out of phase. When v _β is positive at the rise of v _α , “1” is continuously output as shown in FIG. 6, and when v _β is negative at the rise of v _α , as shown in FIG. "-1" is output continuously. Such processing can be easily performed by software.
That is, it is determined whether the phase order is R → S → T or R → T → S depending on whether the output of the positive / negative determining means 21 is “−1” or “1”.

If the range of the angle θ _S of the input voltage vector is set to 0 ° ≦ θ _S <360 ° by multiplying the output of the positive / negative determination unit 21 by the angle detected by the PLL circuit 5 by the multiplication unit 13, the phase When the order is R → S → T, the angle θ _S increases (the input voltage vector rotates counterclockwise), and when the phase order is R → T → S, the angle θ _S decreases (the input voltage vector is clockwise). Rotate in the direction).
That is, the polarity according to the phase order can be added to the angle θ _S detected by the PLL circuit 5 by the conventional method, and the input current command can be generated by the three-phase oscillator 6 using this angle θ _S. .
In FIG. 4, the voltage polarity discriminating means 4, the PLL circuit 5, the multiplying means 13, the three-phase oscillator 6 and the like constitute input current command generating means.

In the present exemplary embodiment, to determine the phase sequence by sign of the other v _beta relative to one v _alpha of the two-phase voltages, to determine the phase sequence by positive and negative v _alpha relative to the v _beta reversed Also good. Further, since the phases of v _α and v _β are shifted by 90 °, v _β or v is within 90 ° before and after the zero cross point of v _α or v _β even if it is not at any rising edge (zero cross point). v may examine the positive and negative _α.

Next, FIG. 7 is a block diagram of a third embodiment of the present invention corresponding to the third aspect.
In this embodiment, the phase order is determined using the output of the input voltage magnitude detection means 9. As in the first and second embodiments, the input voltage magnitude detection result is used without using coordinate transformation, and the phase order of the input voltage is determined by hardware, so that the input of the CPU is not increased. It is possible to generate an input current command corresponding to the phase order of the voltages.
That is, in FIG. 7, phase sequence determination unit 30 is provided on the output side of the input voltage magnitude detection means 9, by multiplying the output by multiplying unit 13 to the output of the PLL circuit 5, the angle of the input voltage vector theta _S Is to add polarity.

Hereinafter, the operation of the phase order determination unit 30 will be described. As described with reference to FIG. 10, the input voltage magnitude detecting means 9 detects the maximum input voltage and the minimum input voltage, and when the X (X is any of R, S, or T) phase is maximum, X _p = 1 (X _p = 0 for the other phase), X _p and X _n (R _p , R _n , S _p , X _n = 1 (X _n = 0 for the other phase) when the X phase is minimum) A combination of “1” and “0” of S _n , T _p , T _n ) is output.

FIG. 9 is a block diagram illustrating a configuration of the phase order determination unit 30. In Figure 9, 41R, 41S, 41T is R, S, T phases of _X p, _{X n} is set (S) input, a RS flip-flop that is applied to the reset (R) input, the R-phase and T-phase The Q outputs R _pn and T _pn of the flip-flops 41 R and 41 T are unchanged and the Q output S _pn of the S-phase flip-flop 41 S is inverted and input to the AND gate 43.
The output of the AND gate 43 is applied to the data (D) input of the latch 42, and the set input (that is, R _p ) of the R-phase flip-flop 41R is applied to the gate (G) input of the latch. The Q output of the latch 42 is Y for convenience.

In the above configuration, the flip-flop 41R, 41S, 41T sets the _{X pn} = 1 on the rising edge of _{X p,} reset to _{X pn} = 0 at the rising edge of _{X n.} This is shown in FIG.
The method for determining the phase sequence of the input voltage is as follows. If the timing at which the R-phase voltage is maximized is used, the signal of S _{pn and} / or T _pn is examined at the rise of R _pn . For example, as shown in FIG. 9, an inverted signal of R _pn · S _pn · T _pn signal (· indicates an AND condition) is obtained by AND gate 43, and the output of AND gate 43 is latched when R _p = 1. What is necessary is just to latch by 42.

As is clear from FIG. 8, when the phase sequence of the input voltage is R → S → T, the output Y of the latch 42 is 1, and when the phase sequence is R → T → S, the output Y of the latch 42 is 0.
Therefore, when Y = 1, this is directly multiplied by the output of the PLL circuit 5 of FIG. 7 as the output of the phase sequence determination means 30, and only when Y = 0, the output of the phase sequence determination means 30 is set to -1. The output of the PLL circuit 5 is multiplied. Thus, as in the second embodiment, if the range of the angle θ _S of the input voltage vector is 0 ° ≦ θ _S <360 °, the angle θ _S increases when the phase sequence is R → S → T. When the phase order is R → T → S, the angle θ _S decreases.
Therefore, the polarity according to the phase order can be added to the angle θ _S detected by the PLL circuit 5, and the input current command can be generated by the three-phase oscillator 6 using the angle θ _S.

  It is not necessary to limit the phase order when the R-phase voltage reaches the maximum voltage as described above. When the R-phase is the minimum voltage, the S-phase and T-phase are the maximum or minimum voltage. Even at times, it is possible to determine the phase order by a circuit having a similar configuration.

It is a block diagram which shows 1st Embodiment of this invention. It is a figure which shows the behavior of an input voltage vector when the phase sequence of a power supply voltage is R-> S-> T. It is a figure which shows the behavior of an input voltage vector when the phase sequence of a power supply voltage is R-> T-> S. It is a block diagram which shows 2nd Embodiment of this invention. It is operation | movement explanatory drawing of 2nd Embodiment when the phase sequence of a power supply voltage is R-> S-> T. It is operation | movement explanatory drawing of 2nd Embodiment when the phase order of a power supply voltage is R-> T-> S. It is a block diagram which shows 3rd Embodiment of this invention. It is a wave form diagram which shows the operation | movement of FIG. It is a block diagram which shows the structure of the phase order determination means in FIG. It is a block diagram which shows a prior art.

Explanation of symbols

1: three-phase AC power supply 2: matrix converter 3: load 6: three-phase oscillator 7: output voltage command generating means 8: pulse generating means 9: input voltage magnitude detecting means 10: three-phase / two-phase converting means 11: angle calculation Means 12: Transformer 13: Multiplication means 21: Positive / negative judgment means 30: Phase order judgment means 41R, 41S, 41T: RS flip-flop 42: Latch 43: AND gate

Claims (3)

The AC switch group configured to form an AC switch group by providing a plurality of bidirectional AC switches composed of at least two unidirectional semiconductor switching elements capable of controlling a unidirectional current, and connected to each phase of a three-phase AC power source A control device for an AC-AC direct conversion power converter that directly converts a three-phase AC voltage into a three-phase AC voltage having an arbitrary magnitude and frequency,
Phase sequence determination means for determining the phase sequence of the input voltage of the power converter;
An input current command generating means for generating an input current command for each phase of the power converter so as to be the same phase order as the phase order determined by the phase order determining means;
In a control device for an AC-AC direct conversion power converter having
The phase order determination means includes
Means for converting a three-phase input voltage into a two-phase quantity in an orthogonal two-axis coordinate system; and means for obtaining an angle of an input voltage vector composed of the two-phase quantity,
The input current command generation means includes
A control apparatus for an AC-AC direct conversion power converter, wherein an input current command for each phase is generated using an angle of the input voltage vector. The AC switch group configured to form an AC switch group by providing a plurality of bidirectional AC switches composed of at least two unidirectional semiconductor switching elements capable of controlling a unidirectional current, and connected to each phase of a three-phase AC power source A control device for an AC-AC direct conversion power converter that directly converts a three-phase AC voltage into a three-phase AC voltage having an arbitrary magnitude and frequency,
Phase sequence determination means for determining the phase sequence of the input voltage of the power converter;
An input current command generating means for generating an input current command for each phase of the power converter so as to be the same phase order as the phase order determined by the phase order determining means;
In a control device for an AC-AC direct conversion power converter having
The phase order determination means includes
Means for converting a three-phase input voltage into a two-phase quantity in an orthogonal two-axis coordinate system; and means for determining a phase order from the phase difference between the two-phase quantities,
The input current command generation means includes
A means for detecting the phase of the input voltage from the polarity of the input voltage of a certain phase, and an angle with polarity based on this phase and the phase order determined by the phase order determining means, and using this angle for each phase A control device for an AC-AC direct conversion type power converter, comprising: means for generating an input current command. The AC switch group configured to form an AC switch group by providing a plurality of bidirectional AC switches composed of at least two unidirectional semiconductor switching elements capable of controlling a unidirectional current, and connected to each phase of a three-phase AC power source A control device for an AC-AC direct conversion power converter that directly converts a three-phase AC voltage into a three-phase AC voltage having an arbitrary magnitude and frequency,
Phase sequence determination means for determining the phase sequence of the input voltage of the power converter;
An input current command generating means for generating an input current command for each phase of the power converter so as to be the same phase order as the phase order determined by the phase order determining means;
In a control device for an AC-AC direct conversion power converter having
The phase order determination means includes
Means for determining the phase order from the phase difference according to the magnitude relationship of the three-phase input voltage,
The input current command generation means includes
A means for detecting the phase of the input voltage from the polarity of the input voltage of a certain phase, and an angle with polarity based on this phase and the phase order determined by the phase order determining means, and using this angle for each phase A control device for an AC-AC direct conversion type power converter, comprising: means for generating an input current command.

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