JP2008172971A - Three-phase voltage ac-dc converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-phase voltage AC-DC converter for blocking an AC power system, and surely detecting an individual operation. <P>SOLUTION: The three-phase voltage AC-DC converter implements a system link operation for controlling a voltage at an AC terminal in an inverter by using a positive feedback, and detects a change in the magnitude or frequency of the voltage at the AC terminal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a three-phase voltage type AC / DC converter that can be applied to an inverter that operates in conjunction with a power system.

  2. Description of the Related Art Conventionally, there is known a method for protecting a grid-connected inverter that can prevent independent operation and reverse charging to an AC power system (see, for example, Patent Document 1). Patent Document 1 describes a “frequency shift method”, a “bandpass filter method”, a “power fluctuation method”, and a “harmonic voltage monitoring method”.

Here, FIG. 10 is a schematic diagram showing the configuration of a conventional three-phase voltage type AC / DC converter. When the AC power system is cut off, the grid-connected inverter changes the current phase based on the frequency of the inverter output voltage, the frequency change rate, and the distortion voltage near the zero cross, thereby changing the frequency of the inverter output voltage to a predetermined value. . The three-phase voltage type AC / DC converter of FIG. 10 detects this and stops the grid interconnection inverter.
Japanese Patent Laid-Open No. 06-311653

  However, since the conventional grid-connected inverter protection method uses the distortion of the excitation voltage of the pole transformer, when the supply power and load power of the grid-connected inverter are approximately equal, the distortion of the excitation voltage is It is considered that it depends on the relationship between the inverter capacity and the pole transformer capacity, and it is difficult to reliably detect that the grid-connected inverter has become an independent operation.

  Therefore, an object of the present invention is to provide a three-phase voltage type AC / DC converter capable of reliably detecting that the AC power system has been cut off and has become an independent operation.

  In order to achieve the above object, the three-phase voltage type AC / DC converter according to the present invention performs system interconnection operation by adding control for positive feedback of the AC voltage of the three-phase voltage type AC / DC converter, and the AC power system is When the operation was interrupted and the operation was performed independently, the frequency or / and amplitude of the output voltage was changed, and the change was detected to determine that the operation was performed independently.

  Specifically, the present invention has an internal equivalent impedance when viewed from the AC terminal, and converts power from a DC voltage source into three-phase AC power according to the pulse width of the gate signal generated based on the PWM command. A three-phase voltage type AC / DC converter circuit that outputs the three-phase AC power from the AC terminal, and an output from the three-phase voltage type AC / DC converter circuit is a component related to the amplitude of the output voltage as a d-axis component. The output voltage vector converted into the dq rotation coordinate space having the component related to the frequency difference as the q-axis component and the amplitude command value for the amplitude of the output voltage of the AC terminal are the d-axis component and the command value for the frequency is the q-axis component. An upper command vector on the dq rotation coordinate space is input, and based on the input output voltage vector and the upper command vector, the amplitude and frequency of the three-phase output voltage of the AC terminal An upper voltage control circuit that outputs a voltage command vector generated so as to approach a command value by the upper command vector, and at least one dq rotational coordinate axis component of the upper command vector input to the upper voltage control circuit, A positive feedback circuit that positively feeds back components of the dq rotation coordinate axis of the output voltage vector, a reference voltage vector that defines the amplitude and phase of the three-phase output voltage of the AC terminal, and the output voltage of the three-phase voltage type AC / DC converter circuit And a signal generated so that the amplitude and phase of the three-phase output voltage are close to the combined value of the reference voltage vector and the voltage command vector based on the vector based on the above and the voltage command vector from the upper voltage control circuit The lower voltage control circuit that outputs the PWM command and the frequency of the three-phase output voltage of the AC terminal are specified. The generated value generated based on the quasi-frequency and the generated value generated based on the q-axis component of the output voltage vector obtained by converting the output from the three-phase voltage type AC / DC converter circuit on the dq rotation coordinate space, the three-phase voltage A frequency control circuit that synchronizes with the rotation angle of the conversion matrix for converting the output from the type AC / DC conversion circuit into the dq rotation coordinate space and / or the rotation angle of the conversion matrix in the upper voltage control circuit, and the three-phase voltage type AC / DC A voltage abnormality detection circuit that monitors the output voltage of the conversion circuit and detects that the monitored voltage has deviated from a preset range as a voltage abnormality. The detection circuit monitors the amplitude value of the output, the frequency of the output, or an amount correlated therewith, and is a three-phase voltage type AC / DC converter.

  The three-phase voltage type AC / DC converter according to the present invention has an internal equivalent impedance so that it can be operated even when connected to a power system as a voltage source. In addition, the three-phase output voltage at the rotation angle of the conversion matrix that is converted into the dq rotation coordinate space with the frequency control circuit converting the component related to the amplitude of the three-phase AC output voltage as the d-axis component and the component related to the frequency difference as the q-axis component The generated values generated from the components related to the frequency difference are synchronized. Thereby, the said rotation angle can be made to follow the frequency of an electric power grid | system. Further, even if the voltage amplitude and frequency of the power system change by the upper voltage control circuit and the frequency control circuit, the respective deviations of the voltage amplitude and frequency of the three-phase output of the three-phase voltage type AC / DC converter with respect to the amplitude and frequency. Minutes can be detected. Therefore, the lower voltage control circuit can compensate for the deviation by controlling the amplitude and phase of the three-phase voltage type AC / DC converter. Further, the dq rotation coordinate axis component of the output voltage vector input to the upper voltage control circuit is positively fed back to at least one dq rotation coordinate axis component of the upper command vector input to the upper voltage control circuit by the positive feedback circuit. As a result, the voltage amplitude or frequency of the AC terminal changes when the power system is cut off and becomes a single operation.

  Therefore, the present invention monitors the voltage amplitude or frequency of the AC terminal and exceeds the predetermined threshold value, so that the AC power system is cut off and can be reliably detected to be operated independently. Can be provided.

  In the three-phase voltage type AC / DC converter according to the present invention, not the voltage amplitude or frequency of the AC terminal, but the amplitude value of the output voltage of the three-phase voltage type AC / DC converter circuit, the frequency of the output voltage, or an amount correlated therewith. Similar effects can be obtained by monitoring. For example, the d-axis component or the q-axis component when the three-phase output voltage at the AC terminal is UM-converted into the dq rotation coordinate space, or the three-phase output voltage at the AC terminal is orthogonal to each other based on one of the three-phase output voltages. The α-axis component or the β-axis component when M-transformed into the αβ static coordinate space that is the α axis and the β axis may be monitored.

  Further, the monitoring point of the amplitude value of the output voltage of the three-phase voltage type AC / DC converter circuit, the frequency of the output voltage or the amount correlated therewith is not the AC terminal, but if they can be monitored, the three-phase voltage type AC / DC converter device Any location may be monitored. For example, the output from the positive feedback point where the output voltage vector is positively fed back to the upper command vector, the output from the upper voltage control circuit, or the output from the lower voltage control circuit may be monitored.

  In the three-phase voltage type AC / DC converter according to the present invention, a gate signal stop function for stopping the gate signal in the three-phase voltage type AC / DC converter circuit or / and the three-phase voltage type AC / DC converter circuit and the AC terminal An inverter output stop means having a shut-off function for shutting off the three-phase AC power from the three-phase voltage type AC / DC converter circuit with a switch in between, the inverter output stop means having a voltage abnormality detection circuit When detecting this, the output of the three-phase AC power from the AC terminal can be stopped.

  By providing a positive feedback circuit that positively feeds back the output voltage vector to the upper command vector, the output voltage of the three-phase voltage type AC / DC converter is Become. Therefore, by providing the inverter output stop means, the three-phase voltage type AC / DC converter circuit can be stopped or the output from the three-phase voltage type AC / DC converter circuit can be shut off when the operation is independent.

  The three-phase voltage type AC / DC converter according to the present invention further includes a switch for cutting off the positive feedback circuit and / or a positive feedback circuit stopping unit for setting the gain of the positive feedback circuit to 0, and the positive feedback circuit stopping unit includes: The inverter output stop means can stop positive feedback of the voltage output vector to the higher order command vector after stopping the output of the three-phase AC power from the AC terminal.

  As described above, when the three-phase voltage type AC / DC converter is operated independently, the output from the three-phase voltage type AC / DC converter circuit is independent of the voltage and frequency of the AC power system due to the provision of the positive feedback circuit. Will fluctuate. Therefore, the positive feedback circuit stopping means is provided, and the positive feedback is stopped after the output of the inverter is stopped by the independent operation.

  Therefore, in addition to the effects as described above, the present invention provides the voltage and frequency of the three-phase voltage type AC / DC converter and the AC power when the grid connection operation is performed again after the inverter output is stopped by detecting the isolated operation. It is possible to avoid a mismatch between the system voltage and frequency.

(Accurate internal equivalent impedance of three-phase voltage type AC / DC converter)
The internal equivalent impedance of the three-phase voltage type AC / DC converter can be calculated as follows. FIG. 8 shows an equivalent circuit of the α axis and the β axis of the three-phase voltage type AC / DC converter according to the present invention. R ₁ , R _2, and C in FIG. 8 are expressed by Equation (1).

なお、三相電圧型交直変換回路の三相電圧型交直変換部での電流アンプとしてのゲインをＧ_ＰＷＭとしている。また、図５における第一電圧制御器６４を増幅器とした場合、当該増幅器のフィードバックゲインをα、フィードフォワード増幅器６８でのフィードフォワードゲインをβとしている。三相電圧型交直変換回路は三相電圧型交直変換部でのゲート信号に起因する高周波成分を除去することができる三相交流フィルタ回路を有する。三相交流フィルタ回路の概略構成図を図９に示す。数式（１）のＣ_Ｆは三相交流フィルタ回路のコンデンサの容量を示す。数式（１）のＲ_Ｆは三相交流フィルタ回路の抵抗値を示す。

The gain as a current amplifier in the three-phase voltage type AC / DC converter of the three-phase voltage type AC / DC converter is G _PWM . When the first voltage controller 64 in FIG. 5 is an amplifier, the feedback gain of the amplifier is α, and the feedforward gain in the feedforward amplifier 68 is β. The three-phase voltage type AC / DC converter circuit includes a three-phase AC filter circuit that can remove a high-frequency component caused by a gate signal in the three-phase voltage type AC / DC converter. FIG. 9 shows a schematic configuration diagram of a three-phase AC filter circuit. C _F of Equation (1) shows the capacitance of the capacitor of the three-phase AC filter circuit. R _{F in} Equation (1) represents the resistance value of the three-phase AC filter circuit.

  The present invention can provide a three-phase voltage type AC / DC converter that can reliably detect that an AC power system is shut off and becomes an independent operation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to embodiment shown below. In addition, in the present specification and drawings, the same reference numerals denote the same components.

(First embodiment)
In FIG. 1, the schematic block diagram of the three-phase voltage type | mold AC / DC converter which concerns on this embodiment is shown.

  A three-phase voltage type AC / DC converter 11 shown in FIG. 1 has an internal equivalent impedance when viewed from an AC terminal 29, and receives power from a DC voltage source (not shown) at a DC terminal 21 based on a PWM command. A three-phase voltage type AC / DC converter circuit 40 that converts AC power to output from the AC terminal 29, a UM converter circuit 31 that converts and outputs the three-phase output voltage of the AC terminal 29 into the dq rotation coordinate space, and an upper command A first higher voltage control circuit 70 for outputting a signal generated based on the vector 120 and the output voltage vector from the UM conversion circuit 31 as a voltage command vector; a reference voltage vector; an output voltage vector from the UM conversion circuit 31; A first lower voltage control circuit 60 for outputting a signal generated based on a voltage command vector from the upper voltage control circuit 70 as a PWM command, a reference frequency, and Includes a frequency control circuit 50 to synchronize the generated value generated based on q-axis component of the output voltage vector to a rotation angle of the rotating coordinate transformation matrix 52 in UM conversion circuit 31 from the M conversion circuit 31, a. Further, the three-phase voltage type AC / DC converter 11 includes a positive feedback circuit 200 that positively feeds back the dq rotational coordinate axis component of the output voltage vector from the UM converting circuit 31 to at least one dq rotational coordinate axis component of the higher order command vector 120, respectively. The voltage abnormality detection circuit 220 that monitors the output voltage of the three-phase voltage type AC / DC converter circuit 40 and detects that the monitored voltage deviates from a preset range as a voltage abnormality, and the three-phase voltage as an inverter output stop means And a switch 230 for cutting off the three-phase AC power from the three-phase voltage type AC / DC converter circuit 40 between the AC / DC converter circuit 40 and the AC terminal 22.

  The three-phase voltage type AC / DC converting circuit 40 converts power from a DC voltage source (not shown) into three-phase AC power according to the pulse width of the gate signal generated by the gate signal generator 41 based on the PWM command. A DC voltage source is a voltage source that outputs a DC voltage by itself, such as a battery, a voltage source that generates and rectifies by a power generation method such as wind power generation, or outputs a DC voltage, or controls a DC capacitor voltage to generate a DC voltage. A voltage source for output can be exemplified. In this case, a blocking inductor is further provided between the AC terminal 29 of the three-phase voltage type AC / DC converter circuit 40 and the AC terminal 22 of the three-phase voltage type AC / DC converter 11, and the three-phase output voltage is supplied to the AC terminal via the blocking inductor. It is good also as outputting from 22. The PWM component in the three-phase voltage type AC / DC converter circuit 40 can be prevented from flowing out to the AC terminal 22 of the three-phase voltage type AC / DC converter 11.

  The UM conversion circuit 31 shown in FIG. 1 uses the following formulas (2) to (4) as the three-phase output voltage of the AC terminal 29, the component related to the amplitude of the voltage as a d-axis component, and the component related to the frequency difference as q. It is converted into a dq rotation coordinate space as an axis component and output. In Equation (4), the three-phase output voltage input to the UM conversion circuit 31 is (Va, Vb, Vc), and the output voltage vector (d-axis component, q-axis component) from the UM conversion circuit 31 is (Vd, Vq). In FIG. 1, the UM conversion circuit 31 outputs the frequency control circuit 50, the first lower voltage control circuit 60, and the first upper voltage control circuit 70, respectively. Here, the three-phase output voltage of the AC terminal 29 is detected when performing the UM conversion according to the equations (2) to (4). In this case, three phases of the three-phase output voltage may be detected. However, since any one of the three-phase output voltages is determined, the remaining one voltage is determined. Any two of the phase output voltages may be detected.

  The frequency control circuit 50 generates a generated value based on the reference frequency that defines the frequency of the three-phase output voltage of the AC terminal 22 and the q-axis component of the output voltage vector from the UM conversion circuit 31 in the UM conversion circuit 31. The rotation angle of the rotation coordinate transformation matrix 52 is synchronized. Specifically, as shown in FIG. 5, a low-pass filtering element is added to the q-axis component that is a component related to the frequency difference of the three-phase output voltage in the loop filter 53, and time integration is performed by the second time integrator 55. Output. The low-pass filtering element added in the loop filter 53 can be exemplified by a delay element such as a first-order delay element. Thereby, the feedback loop can be stabilized.

  Further, a generated value 57 generated by adding the integrated value from the second time integrator 55 to the integrated value obtained by integrating the reference frequency output from the reference frequency setting unit 51 with the first time integrator 54 with time. Is synchronized with the rotation angle of the rotation coordinate conversion matrix 52 in the UM conversion circuit 31. Thereby, the said rotation angle can be made to follow the frequency of an electric power grid | system. In order to synchronize, the generated value 57 obtained by adding the integral value from the first time integrator 54 and the integral value from the second time integrator 55 is defined as θdq in Equation (4).

  Here, the UM conversion circuit 31 outputs a component (q-axis component) related to the frequency difference of the three-phase output voltage as described above. Therefore, the signal processing in the UM conversion circuit 31 compares the phases of the three-phase output voltage, the generated value 57 obtained by adding the integrated value from the first time integrator 54 and the integrated value from the second time integrator 55. This is considered to correspond to the phase comparison process. Further, in the signal processing by adding the integral value from the first time integrator 54 and the integral value from the second time integrator 55, the value of the generated value is varied according to the output voltage from the loop filter 53. This is considered to correspond to signal processing of a VCO (Voltage Controlled Oscillator). Therefore, as a whole, the UM conversion circuit 31 and the frequency control circuit 50 have a generated value 57 obtained by adding the integration value from the first time integrator 54 and the integration value from the second time integrator 55 at the three AC terminals 22. It is considered that the operation as a PLL synchronized with the frequency of the phase output voltage is performed. Therefore, the frequency range for maintaining synchronization (synchronization holding range (lock range)) and the frequency pull-in range (capture range) can be obtained in the same manner as in the case of the PLL.

  A first upper voltage control circuit 70 shown in FIG. 1 receives a higher command vector 120 composed of a voltage amplitude command value for the amplitude of the three-phase output voltage at the AC terminal 22 and a frequency command value for the frequency. Then, based on the input upper command vector 120 and the output voltage vector from the UM conversion circuit 31, a signal generated so that the amplitude and frequency of the three-phase output voltage of the AC terminal 22 approach the command value by the upper command vector 120. Is output as a voltage command vector. Specifically, as shown in FIG. 5, the subtractor 72 subtracts the output vector from the UM conversion circuit 31 and the upper command vector 120, and the voltage amplitude and frequency of the power system are changed to the command value by the upper command vector 120. Amplifying by the first upper control amplifier 71 so as to approach, a voltage command vector is generated and output. Thereby, even if the voltage amplitude and frequency of an electric power system change, the deviation of each of the voltage amplitude and frequency of the three-phase output of the three-phase voltage type | mold AC / DC converter 11 with respect to the said amplitude and frequency is detectable.

  The first lower voltage control circuit 60 of FIG. 1 includes a reference voltage vector that defines the amplitude and phase of the three-phase output voltage at the AC terminal 22, the output voltage vector from the UM conversion circuit 31, and the first upper voltage control circuit 70. Based on the voltage command vector, a signal generated so that the amplitude and phase of the three-phase output voltage approaches the combined value of the reference voltage vector and the voltage command vector is output as a PWM command. The reference voltage vector is set in advance by the first reference voltage vector setter 61. This reference voltage vector is a two-phase reference of the amplitude and phase of the three-phase output voltage of the AC terminal 22.

  Specifically, as shown in FIG. 5, the voltage command vector from the first higher voltage control circuit 70 is added to the reference voltage vector set in advance in the first reference voltage vector setter 61 in the adder 62 to obtain power. Add compensation for system voltage amplitude and phase deviation. Further, the output voltage vector from the UM conversion circuit 31 is subtracted by the subtractor 63, and the difference between the voltage amplitude and phase of the power system approaches the combined value of the reference voltage vector and the voltage command vector by the first voltage controller 64. Is converted and output. Further, the output vector in the dq space from the first voltage controller 64 is converted into the αβ space in the first inverse U converter 65 and output as a PWM command to the three-phase voltage type AC / DC converter circuit 40. Thus, the deviation detected by the first higher voltage control circuit 70 is compensated, and the amplitude and phase of the three-phase output voltage of the three-phase voltage type AC / DC converter 11 are matched with the voltage amplitude and phase of the power system. The amplitude and phase of the three-phase voltage type AC / DC converter 11 can be controlled.

  The positive feedback circuit 200 causes the first higher voltage control circuit 70 to output a voltage command vector so that the three-phase AC voltage output to the AC terminal 29 becomes unstable when the power system fails and becomes independent. Will do. Specifically, it operates as follows.

Here, V ^* _FILq is a q-axis filter voltage command value of the three-phase voltage type AC / DC converter, V _FILq is an actually measured q-axis filter voltage, and V ^* _FILd is a d-axis filter voltage command value of the three-phase voltage type AC / DC converter. , V _FILd is an actually measured d-axis filter voltage.

ここで、ｋ_ｑはゲイン（ｋ_ｑ＞０）、Ｖ^＊ _{ＦＩＬｑｑ}はｑ軸電圧指令値［Ｖ］である。ｋ_ｑ＞０より、正帰還である。 (When positively feeding back the q-axis component of the output voltage vector from the UM conversion circuit 31)
Let V ^* _FILq be Equation (5).

Here, k _q is a gain (k _q > 0), and V ^* _FILqq is a q-axis voltage command value [V]. From k _q > 0, it is a positive feedback.

During grid interconnection operation, V _FILq is fixed because the output frequency and output voltage amplitude of the inverter are equal to the value of the power system.

In the case of a single operation, since the positive feedback is applied to V ^* _FILq due to the gain k _q > 0 of the positive feedback circuit 200 in FIG. 1, V _FILq becomes larger than the value during the grid interconnection operation. Specifically, as shown in FIG. 5, a value obtained by adding the output of the positive feedback circuit 200 and the upper command vector 120 in the adder 210 is subtracted from the output vector from the UM conversion circuit 31 in the subtractor 72. The gain k _q of the positive feedback circuit 200 is set to a value that satisfies Equation (6). For this reason, since positive feedback is applied to V ^* _FILq , V _FILq is larger than the value during grid interconnection operation. Here, k _vq is the q-axis gain of the first higher voltage control circuit 70.

Since the output frequency F _{i of the} inverter is determined by Equation (7), if V _FILq increases, F _i greatly changes from the inverter reference frequency F _CO . Therefore, the isolated operation can be detected by monitoring the output frequency F _i with the frequency relay of the voltage abnormality detection circuit 220 or the like. Here, K _f is a voltage frequency conversion gain in the frequency control circuit 50.

ここで、ｋ_ｄはゲイン（ｋ_ｄ＞０）、Ｖ^＊ _{ＦＩＬｄｄ}はｄ軸電圧指令値［Ｖ］である。ｋ_ｄ＞０より、正帰還である。 (When the d-axis component of the output voltage vector from the UM conversion circuit 31 is positively fed back)
Let V ^* _FILd be Equation (8).

Here, k _d is a gain (k _d > 0), and V ^* _FILdd is a d-axis voltage command value [V]. From k _d > 0, it is a positive feedback.

During grid interconnection operation, V _FILq is fixed because the output frequency and output voltage amplitude of the inverter are equal to the value of the power system.

In the case of a single operation, a positive feedback is applied to V ^* _FILd due to the gain k _d > 0 of the positive feedback circuit 200 of FIG. 1, so that V _FILd becomes larger than the value during the grid interconnection operation. Specifically, as shown in FIG. 5, a value obtained by adding the output of the positive feedback circuit 200 and the upper command vector 120 in the adder 210 is subtracted from the output vector from the UM conversion circuit 31 in the subtractor 72. The gain k _d of the positive feedback circuit 200 is set to a value that satisfies the formula (9). For this reason, since positive feedback is applied to V ^* _FILd , V _FILd is larger than the value during grid interconnection operation. Here, k _vd is the d-axis gain of the first higher voltage control circuit 70.

Since V _FILD is the amplitude of the inverter output _voltage, the larger the _{V FILD,} the inverter output voltage changes significantly from the reference voltage _{V CO.} Therefore, the isolated operation can be detected by monitoring the voltage amplitude with a voltage relay or the like of the voltage abnormality detection circuit 220.

  The voltage abnormality detection circuit 220 in FIG. 1 includes a voltage detection circuit, a voltage relay, and an abnormality detection circuit. The voltage abnormality detection circuit 220 may include a voltage detection circuit, a frequency relay, and an abnormality detection circuit. The voltage abnormality detection circuit 220 sets a monitoring point between the three-phase voltage type AC / DC conversion circuit 40 and the AC terminal 22, and calculates the voltage or frequency of the three-phase AC between the three-phase voltage type AC / DC conversion circuit 40 and the AC terminal 22. Monitor. The voltage abnormality detection circuit 220 may monitor the voltage of the q-axis component and / or the d-axis component of the vector obtained by UM conversion of the output of the three-phase voltage type AC / DC conversion circuit 40. Further, the voltage abnormality detection circuit 220 is a vector obtained by U-converting the output of the three-phase voltage type AC / DC conversion circuit 40 into the αβ and ββ stationary coordinate spaces orthogonal to each other on the basis of one of the three-phase AC voltages. The voltage of the α-axis component or / and the β-axis component may be monitored. The three-phase voltage type AC / DC converter 11 can determine that the voltage abnormality detection circuit 220 has been operated independently by detecting the voltage abnormality. The voltage abnormality detection circuit 220 in FIGS. 1 and 5 monitors between the switch 230 and the AC terminal 22, but may monitor between the three-phase voltage type AC / DC converter circuit 40 and the switch 230. .

  The voltage abnormality detection circuit 220 in FIG. 1 monitors the output of the three-phase voltage type AC / DC conversion circuit 40, but serves as a positive feedback point where the output voltage vector from the positive feedback circuit 200 is positively fed back to the upper command vector 120. The output from the adder 210, the output from the first upper voltage control circuit 70, or the output from the first lower voltage control circuit 60 may be monitored. Monitoring by the voltage abnormality detection circuit 220 of the output from the adder 210 as the positive feedback point, the output from the first higher voltage control circuit 70 or the output from the first lower voltage control circuit 60 is performed on the dq rotation coordinate space. It may be the voltage of the q-axis component or / and d-axis component of the vector, the voltage of the α-axis component or / and β-axis component of the vector in the αβ static coordinate space, or a value obtained by inverse UM conversion or inverse U conversion.

(Example 1)
FIG. 6 shows an operation example when the q-axis component of the output voltage vector from the UM conversion circuit 31 is positively fed back in the three-phase voltage type AC / DC converter 11. The three-phase voltage type AC / DC converter 11 is connected to a 200 V, 50 Hz power system with a load of 2 kW and a power factor of 1.0. Since the output of the three-phase voltage type AC / DC converter 11 is P = 2 kW and Q = 0 kvar, the interconnection power flow is zero.

  When the interconnection breaker is released at time t = 100 ms, the output frequency of the three-phase voltage type AC / DC converter 11 gradually increases. It rises about 5Hz 60ms after the release of the interconnection breaker.

  FIG. 7 is an operation example when the d-axis component of the output voltage vector from the UM conversion circuit 31 is positively fed back in the three-phase voltage type AC / DC converter 11. The three-phase voltage type AC / DC converter 11 is connected to a 200 V, 50 Hz power system with a load of 2 kW and a power factor of 1.0. Since the output of the three-phase voltage type AC / DC converter 11 is P = 2 kW and Q = 0 kvar, the interconnection power flow is zero.

  When the interconnection breaker is released at time t = 100 ms, the absolute value of the voltage of the three-phase voltage type AC / DC converter 11 increases. The maximum voltage is 360 V which is the DC voltage of the three-phase voltage type AC / DC converter 11.

  The three-phase voltage type AC / DC converter 11 further includes inverter output stopping means. The inverter output stop means in FIG. 1 is a switch 230 provided between the gate signal stop unit and / or the three-phase voltage type AC / DC converter circuit 40 and the AC terminal 22. The gate signal stop unit stops the gate signal from the gate signal generator 41 in the three-phase voltage type AC / DC conversion circuit 40 when the voltage abnormality detection circuit 220 detects a voltage abnormality, and the three-phase voltage type AC / DC conversion circuit. The output of the three-phase AC power from 40 is stopped. On the other hand, when the voltage abnormality detection circuit 220 detects a voltage abnormality, the switch 230 cuts off the three-phase AC power from the three-phase voltage type AC / DC conversion circuit 40 and outputs the three-phase AC power from the AC terminal 22. Stop. The three-phase voltage type AC / DC converter 11 shown in FIGS. 1 and 5 includes a gate signal stop unit and a switch 230 that stop the gate signal generator 41 as an inverter output stop unit.

  The three-phase voltage type AC / DC converter 11 includes the inverter output stop means, so that when the voltage abnormality detection circuit 220 detects a voltage abnormality, that is, during the single operation, the output of the three-phase AC voltage to the outside can be cut off.

  The three-phase voltage type AC / DC converter 11 further includes positive feedback circuit stopping means. The positive feedback circuit stop means is a switch for opening and closing the positive feedback circuit 200 and / or an instruction circuit for setting the gain of the positive feedback circuit 200 to zero. FIG. 4 shows the three-phase voltage type AC / DC converter 11 when the switch 240 is employed as the positive feedback circuit stopping means. The positive feedback circuit stop means stops positive feedback of the voltage output vector to the upper command vector 120 performed by the positive feedback circuit 200 when the voltage abnormality detection circuit 220 detects a voltage abnormality. The three-phase voltage type AC / DC converter 11 includes positive feedback circuit stopping means, so that when the voltage abnormality detection circuit 220 detects a voltage abnormality, that is, the frequency of the three-phase alternating current from the three-phase voltage type AC / DC converter circuit 40 during single operation. It is possible to prevent the voltage amplitude from fluctuating greatly.

  In FIG. 5, the schematic block diagram of the other form of the three-phase voltage type | mold AC / DC converter 11 is shown. The three-phase voltage type AC / DC converter 11 shown in FIG. 5 detects a three-phase output current of the AC terminal 22 in the three-phase voltage type AC / DC converter 11 shown in FIG. And a UM conversion circuit 81 that converts the signal into a dq rotation coordinate space and outputs the converted signal, and further adds a filter current compensator 66, a PWM current deviation compensator 67, and a feed forward to the output vector from the first voltage controller 64. The output vector from the amplifier 68 is added in the adder 69. Further, the dq conversion in the UM conversion circuit 81 is the same as the coordinate conversion described in Expressions (2) to (4). That is, the UM conversion circuit 81 outputs the component related to the active power of the detected current signal as the d-axis component and the component related to the reactive power as the q-axis component.

  The filter current compensator 66 outputs a current compensation vector defined so as to compensate for a current loss in the three-phase AC filter circuit in the three-phase voltage type AC / DC converter circuit 40. As a result, in the three-phase voltage type AC / DC converter 11, the current loss in the three-phase AC filter circuit is set in the filter current compensator 66 in advance and added to the output vector from the first voltage controller 64 to obtain the loss. Can be compensated. The PWM current deviation compensator 67 outputs a current deviation compensation vector defined so as to compensate the current deviation of the three-phase output current from the three-phase voltage type AC / DC converting circuit 40. Thus, in the three-phase voltage type AC / DC converter 11, the current deviation in the three-phase voltage type AC / DC converter circuit 40 when the PWM command is set to zero command is set in advance in the PWM current deviation compensator 67, and the first voltage control is performed. The loss can be compensated by adding to the output vector from the generator 64. The feedforward amplifier 68 amplifies the output current vector from the UM conversion circuit 81 with a predetermined feedforward gain so as to compensate the current flowing through the AC terminal 22 and outputs the amplified output current vector. Thereby, in the three-phase voltage type | mold AC / DC converter 11, the effective / invalid component of a three-phase output current is detected by detecting the three-phase output current of the alternating current terminal 22 in the current detection circuit 80, and carrying out dq conversion, and those values Is added to the output vector from the first voltage controller 64 through the feedforward amplifier 68, so that a stable output voltage can be generated even if the load current changes.

  As described above, since the three-phase voltage type AC / DC converter 11 of FIGS. 1 and 5 has an internal equivalent impedance, it can be operated by being connected to a power system as a voltage source, and a frequency setting circuit, Since the first upper voltage control circuit and the first lower voltage control circuit are provided, autonomous parallel operation that autonomously compensates for the power deviation with respect to the power system is possible.

  Further, the three-phase voltage type AC / DC converter 12 can detect the single operation by the positive feedback circuit 200 and the voltage abnormality detection circuit 220, and outputs the three-phase AC voltage during the single operation to the outside by the inverter output stop means. In addition, the positive feedback circuit stop means can prevent the frequency and voltage amplitude of the three-phase alternating current from the three-phase voltage type AC / DC converting circuit 40 from changing greatly.

  It is also possible to detect a case where the system voltage is in an open phase state. In FIG. 7, since the absolute value of the voltage of the three-phase voltage type AC / DC converter 11 after time t = 100 ms is large, it is possible to detect the isolated operation state, but there are cases where the system voltage is in an open phase state. It is possible to detect that the absolute value of the voltage of the three-phase voltage type AC / DC converter 11 becomes large, although not as remarkable as in the single operation state.

  In addition, it can be identified by the degree of change of the absolute value of the voltage of the voltage type | mold AC / DC converter 11 for several 100 ms whether it is a single operation state or a phase loss state.

  Also, for example, when one of the three phases is in an open phase state, a vibration having a frequency twice the power system frequency is superimposed on the signal output from the UM conversion circuit 31. It is also possible to identify whether the phase is in an open phase state or a single operation state.

(Second Embodiment)
In FIG. 2, the schematic block diagram of the three-phase voltage type | mold AC / DC converter which concerns on this embodiment is shown.

  The three-phase voltage type AC / DC converter 12 shown in FIG. 2 has an internal equivalent impedance when viewed from the AC terminal 22, and converts power from a DC voltage source (not shown) into three-phase AC power based on a PWM command. A three-phase voltage type AC / DC converter circuit 40 that is output from the AC terminal 22, an M converter circuit 32 that converts the three-phase output voltage of the AC terminal 22 into an αβ static coordinate space, and an output voltage vector of the M converter circuit 32 by dq rotation A U conversion circuit 33 that converts and outputs the result on the coordinate space; a second upper voltage control circuit 90 that outputs a signal generated based on the upper command vector 120 and the output voltage vector from the U conversion circuit 33 as a voltage command vector; A signal generated based on the reference voltage vector, the output voltage vector from the M conversion circuit 32, and the voltage command vector from the second upper voltage control circuit 90 is used as a PWM command. Rotation of the rotation coordinate transformation matrix 52 in the U conversion circuit 33 is performed by using the second lower voltage control circuit 80 that outputs the reference value and the generated value generated based on the reference frequency and the q-axis component of the output voltage vector from the U conversion circuit 33. A frequency control circuit 50 synchronized with the angle. Compared with the three-phase voltage type AC / DC converter 11 described in the first embodiment, the three-phase voltage type AC / DC converter 12 according to this embodiment performs signal processing in the second lower voltage control circuit 80 by αβ stationary. The difference is that it is performed on the coordinate space, and the positive feedback circuit 200 positively feeds back the output obtained by converting the output from the M conversion circuit 32 by the U conversion circuit 33 to the upper command vector 120. In FIG. 2, the same reference numerals as those in FIGS. 1 and 5 indicate the same components, and thus the description thereof is omitted.

  The M conversion circuit 32 converts one of the three-phase output voltages of the AC terminal 22 into an αβ static coordinate space having α and β axes orthogonal to each other. The transformation matrix can be expressed by the above mathematical formula (3). The U conversion circuit 33 converts the output voltage vector of the M conversion circuit 32 into a dq rotation coordinate space in which a component related to the amplitude of the three-phase output voltage is a d-axis component and a component related to a frequency difference is a q-axis component. Output. The transformation matrix can be expressed by the above mathematical formula (2). Therefore, since the output from the U conversion circuit 33 passes through the M conversion circuit 32, a vector having the same quality as the output from the UM conversion circuit 31 in FIG. 1 is output.

  The second upper voltage control circuit 90 in FIG. 2 receives the upper command vector 120 including the voltage amplitude command value for the amplitude of the three-phase output voltage at the AC terminal 22 and the frequency command value for the frequency. Then, based on the input upper command vector 120 and the output voltage vector from the U conversion circuit 33, a signal generated so that the amplitude and frequency of the three-phase output voltage of the AC terminal 22 approach the command value by the upper command vector 120. Is output as a voltage command vector via the first inverse U converter 91. Specifically, as described in the first upper voltage control circuit 70 of FIG. 5, the output vector from the U conversion circuit 33 and the upper command vector 120 are subtracted in the subtractor, and the voltage amplitude and frequency of the power system are Amplification is performed by the second upper control amplifier so as to approach the command value by the upper command vector 120, and the first inverse U converter 91 converts it into the αβ static coordinate space to generate a voltage command vector. Thereby, even if the voltage amplitude and frequency of an electric power system change, the deviation of each of the voltage amplitude and frequency of the three-phase output of the three-phase voltage type | mold AC / DC converter with respect to the said amplitude and frequency is detectable.

  The second lower voltage control circuit 80 in FIG. 2 includes a reference voltage vector that defines the amplitude and phase of the three-phase output voltage at the AC terminal 22, the output voltage vector from the M conversion circuit 32, and the second upper voltage control circuit 90. Based on the voltage command vector, a signal generated so that the amplitude and phase of the three-phase output voltage approaches the combined value of the reference voltage vector and the voltage command vector is output as a PWM command. Specifically, the second lower voltage control circuit 80 includes a second voltage controller as an alternative to the first voltage controller 64 of the first lower voltage control circuit 60 described in FIG. The first inverse U converter 65 of the control circuit 60 is not provided. The voltage command vector from the second higher voltage control circuit 90 is added to the reference voltage vector preset in the first reference voltage vector setter 81 by the adder, and compensation for voltage system voltage amplitude and frequency deviation is added. To do. Further, the output voltage vector from the M conversion circuit 32 is subtracted by the subtractor, and the difference between the voltage amplitude and phase of the power system is approximated to the combined value of the reference voltage vector and the voltage command vector by the second voltage controller. The signal is converted and output as a PWM command to the three-phase voltage type AC / DC converting circuit 40. As a result, the deviation detected by the second upper voltage control circuit 90 is compensated, and the amplitude and phase of the three-phase output voltage of the three-phase voltage type AC / DC converter 12 are matched with the voltage amplitude and phase of the power system. The amplitude and phase of the three-phase voltage type AC / DC converter 12 can be controlled.

  The three-phase voltage type AC / DC converter 12 shown in FIG. 2 includes the positive feedback circuit 200 and the voltage abnormality detection circuit 220 described with reference to FIGS. 1 and 5. Therefore, the three-phase voltage type AC / DC converter 12 can determine that the voltage abnormality detection circuit 220 has been operated independently by detecting the voltage abnormality.

  The three-phase voltage type AC / DC converter 12 shown in FIG. 2 includes the inverter output stopping means described in FIGS. 1 and 5. The inverter output stop means in FIG. 2 is a switch 230 provided between the gate signal stop unit and / or the three-phase voltage type AC / DC converter circuit 40 and the AC terminal 22. Therefore, the three-phase voltage type AC / DC converter 12 can shut off the output of the three-phase AC voltage to the outside when the voltage abnormality detection circuit 220 detects a voltage abnormality, that is, during an independent operation.

  The three-phase voltage type AC / DC converter 12 further includes positive feedback circuit stopping means. 2 is a switch for opening and closing the positive feedback circuit 200 and / or an instruction circuit for setting the gain of the positive feedback circuit 200 to zero. Therefore, in the three-phase voltage type AC / DC converter 12, when the voltage abnormality detection circuit 220 detects a voltage abnormality, that is, in the single operation, the frequency and voltage amplitude of the three-phase AC from the three-phase voltage type AC / DC conversion circuit 40 fluctuate significantly. Can be prevented.

  The three-phase voltage type AC / DC converter 12 shown in FIG. 2 includes the feedforward amplifier 68 described in FIG. 5, the current detection circuit 80 and the M conversion circuit 32 necessary for the amplifier, the filter current compensator 66, and the PWM current deviation compensator. 67, and the output from these circuits can be added to the output vector from the second voltage controller 84 in the second lower voltage control circuit 80.

  As described above, the three-phase voltage type AC / DC converter 12 shown in FIG. 2 has an internal equivalent impedance in the same manner as the three-phase voltage type AC / DC converter 11 shown in FIGS. Since the frequency control circuit 50, the second upper voltage control circuit 90, and the second lower voltage control circuit 80 are provided, autonomous parallel operation that autonomously compensates for power deviation with respect to the power system is possible. is there.

  Furthermore, the three-phase voltage type AC / DC converter 12 can detect the single operation by the positive feedback circuit 200 and the voltage abnormality detection circuit 220, and the three-phase AC voltage during the single operation by the inverter output stop means and the positive feedback circuit stop means. Can be cut off, and the frequency and voltage amplitude of the three-phase alternating current from the three-phase voltage type AC / DC converting circuit 40 can be prevented from greatly fluctuating.

(Third embodiment)
In FIG. 3, the schematic block diagram of the three-phase voltage type | mold AC / DC converter which concerns on this embodiment is shown.

  The three-phase voltage type AC / DC converter 13 shown in FIG. 3 has an internal equivalent impedance when viewed from the AC terminal 22 and converts power from a DC voltage source (not shown) into three-phase AC power based on a PWM command. Three-phase voltage type AC / DC conversion circuit 40 that outputs from AC terminal 22, UM conversion circuit 31 that converts and outputs the three-phase output voltage of AC terminal 22 on the dq rotation coordinate space, upper command vector 120 and UM conversion circuit A third upper voltage control circuit 110 that outputs a signal generated based on the output voltage vector from 31 as a voltage command vector; a reference voltage vector; a three-phase output voltage of the AC terminal 22; and a third upper voltage control circuit 110 The third lower voltage control circuit 100 that outputs a signal generated based on the voltage command vector as a PWM command, the reference frequency, and the output from the UM conversion circuit 31. It includes a frequency control circuit 50 to synchronize the generated value generated based on the q-axis component of the voltage vector to the rotation angle of the rotating coordinate transformation matrix 52 in UM conversion circuit 31, a. Compared with the three-phase voltage type AC / DC converter 11 described in the first embodiment, the three-phase voltage type AC / DC converter 13 according to this embodiment performs three-phase signal processing in the third lower voltage control circuit 100. The point to do is different. 6 and 7, the same reference numerals as those in FIGS. 1 and 2 indicate the same components, and thus the description thereof is omitted.

  The third upper voltage control circuit 110 receives an upper command vector 120 composed of a voltage amplitude command value for the amplitude of the three-phase output voltage at the AC terminal 22 and a frequency command value for the frequency. Then, based on the input upper command vector 120 and the output voltage vector from the UM conversion circuit 31, a signal generated so that the amplitude and frequency of the three-phase output voltage of the AC terminal 22 approaches the command value by the upper command vector. Output as a voltage command vector.

  Specifically, as described with reference to the first upper voltage control circuit 70 in FIG. 5, the third upper voltage control circuit 110 in FIG. 3 uses the output vector from the UM conversion circuit 31 and the upper command vector 120 in the subtractor. Is amplified by the third upper control amplifier so that the voltage amplitude and frequency of the power system approach the command value by the upper command vector 120, and the inverse UM converter 111 performs the inverse transform from the dq rotation coordinate space. Generate a voltage command vector. Thereby, even if the voltage amplitude and frequency of an electric power system change, the deviation of each of the voltage amplitude and frequency of the three-phase output of the three-phase voltage type | mold AC / DC converter 13 with respect to the said amplitude and frequency is detectable.

  The third lower voltage control circuit 100 in FIG. 3 includes a reference voltage vector that defines the amplitude and phase of the three-phase output voltage at the AC terminal 22, the three-phase output voltage at the AC terminal 22, and the voltage from the third upper voltage control circuit 110. Based on the command vector, a signal generated so that the amplitude and phase of the three-phase output voltage approaches the combined value of the reference voltage vector and the voltage command vector is output as a PWM command. Specifically, the third lower voltage control circuit 100 includes a second reference voltage vector setter 101 as an alternative to the first reference voltage vector setter 61 of the first lower voltage control circuit 60 described in FIG. A third voltage controller is provided as an alternative to the first voltage controller 64, and the first inverse U converter 65 of the first lower voltage control circuit 60 is not provided. The reference voltage vector is set in advance by the second reference voltage vector setter 101. This reference voltage vector is a reference for the amplitude and phase of the three-phase output voltage of the AC terminal.

  Specifically, the voltage command vector from the third higher voltage control circuit 110 is added to the reference voltage vector preset in the second reference voltage vector setter 101 by the adder, and the voltage amplitude and frequency deviation of the power system are added. Add compensation for. Further, the three-phase output voltage vector of the AC terminal 22 is subtracted by the subtractor, and the difference between the voltage amplitude and phase of the power system is approximated to the combined value of the reference voltage vector and the voltage command vector by the third voltage controller. The signal is converted and output as a PWM command to the three-phase voltage type AC / DC converting circuit 40. As a result, the deviation detected by the third upper voltage control circuit 110 is compensated, and the amplitude and phase of the three-phase output voltage of the three-phase voltage type AC / DC converter 13 are matched with the voltage amplitude and phase of the power system. The amplitude and phase of the three-phase voltage type AC / DC converter 13 can be controlled.

  The three-phase voltage type AC / DC converter 13 shown in FIG. 3 includes the positive feedback circuit 200 and the voltage abnormality detection circuit 220 described with reference to FIGS. 1 and 5. Therefore, the three-phase voltage type AC / DC converter 13 can determine that the voltage abnormality detection circuit 220 has been operated independently by detecting the voltage abnormality.

  The three-phase voltage type AC / DC converter 13 shown in FIG. 3 includes the inverter output stopping means described in FIGS. 1 and 5. The inverter output stop means in FIG. 2 is a switch 230 provided between the gate signal stop unit and / or the three-phase voltage type AC / DC converter circuit 40 and the AC terminal 22. Therefore, the three-phase voltage type AC / DC converter 13 can shut off the output of the three-phase AC voltage to the outside when the voltage abnormality detection circuit 220 detects a voltage abnormality, that is, during single operation.

  The three-phase voltage type AC / DC converter 13 further includes positive feedback circuit stopping means. The positive feedback circuit stop means in FIG. 3 is a switch for opening / closing the positive feedback circuit 200 and / or an instruction circuit for setting the gain of the positive feedback circuit 200 to zero. Therefore, in the three-phase voltage type AC / DC converter 13, when the voltage abnormality detection circuit 220 detects a voltage abnormality, that is, in the single operation, the frequency and voltage amplitude of the three-phase AC from the three-phase voltage type AC / DC conversion circuit 40 fluctuate significantly. Can be prevented.

  The three-phase voltage type AC / DC converter 13 shown in FIG. 3 further includes the feedforward amplifier 68 described with reference to FIG. 5, the current detection circuit 80 necessary for this, a filter current compensator 66, and a PWM current deviation compensator 67. Thus, the output from these circuits can be added to the output vector from the third voltage controller in the third lower voltage control circuit 100.

  Furthermore, the three-phase voltage type AC / DC converter 12 can detect the single operation by the positive feedback circuit 200 and the voltage abnormality detection circuit 220, and the three-phase AC voltage during the single operation by the inverter output stop means and the positive feedback circuit stop means. Can be cut off, and the frequency and voltage amplitude of the three-phase alternating current from the three-phase voltage type AC / DC converting circuit 40 can be prevented from greatly fluctuating.

  As described above, the three-phase voltage type AC / DC converter 13 shown in FIG. 3 has an internal equivalent impedance similar to the three-phase voltage type AC / DC converter 11 shown in FIGS. 1 and 5 and is therefore connected to the power system as a voltage source. Since the frequency control circuit 50, the third upper voltage control circuit 110, and the third lower voltage control circuit 100 are provided, autonomous parallel operation that autonomously compensates for power deviation with respect to the power system is possible. is there.

  The three-phase voltage type AC / DC converter of the present invention includes a UPS (uninterruptible power supply) that requires parallel redundant operation, an inverter for photovoltaic power generation, an inverter for fuel cell, an inverter for power storage system, and an inverter for wind power generation with DC link. It can be applied to inverters for distributed power sources such as rectifiers, SVCs (reactive power compensators) and the like.

It is a schematic block diagram of the three-phase voltage type | mold AC / DC converter which concerns on one Embodiment. It is a schematic block diagram of the three-phase voltage type | mold AC / DC converter which concerns on one Embodiment. It is a schematic block diagram of the three-phase voltage type | mold AC / DC converter which concerns on one Embodiment. It is a schematic block diagram of the three-phase voltage type | mold AC / DC converter which concerns on one Embodiment. It is a schematic block diagram of the three-phase voltage type | mold AC / DC converter which concerns on one Embodiment. About the three-phase voltage type AC / DC converter shown in FIG. 5 when the q-axis component of the output voltage vector from the UM converter circuit is positively fed back, the voltage waveform and power waveform at the AC terminal when switching from grid-connected operation to isolated operation It is the figure which showed the current waveform. About the three-phase voltage type AC / DC converter shown in FIG. 5 when the d-axis component of the output voltage vector from the UM converter circuit is positively fed back, the voltage waveform and power waveform at the AC terminal when switching from grid-connected operation to isolated operation It is the figure which showed the current waveform. It is an equivalent circuit diagram of the three-phase voltage type AC / DC converter according to the present invention. It is a schematic block diagram of the three-phase AC filter circuit of the three-phase voltage type | mold AC / DC conversion circuit contained in the three-phase voltage type | mold AC / DC converter which concerns on this invention. It is a schematic block diagram of the conventional three-phase voltage type | mold AC / DC converter.

Explanation of symbols

10, 11, 12, 13: Three-phase voltage type AC / DC converter 21: DC terminal 22: AC terminal 23: DC voltage source 29: AC terminal 31: UM converter circuit 32: M converter circuit 33: U converter circuit 34: current Detection circuits 35 and 81: UM conversion circuit 40: three-phase voltage type AC / DC conversion circuit 41: gate signal generator 50: frequency control circuit 51: reference frequency setting unit 52: rotational coordinate conversion matrix 53: loop filter 54: first time Integrator 55: Second time integrator 56: Adder 57: Addition value 60: First lower voltage control circuit 61: First reference voltage vector setter 62: Adder 63: Subtractor 64: First voltage controller 65: first inverse U converter 66: filter current compensator 67: PWM current deviation compensator 68: feedforward amplifier 69: adder 70: first higher voltage control circuit 71: subtractor 72: first higher control increase Unit 80: Second lower voltage control circuit 81: First reference voltage vector setter 82: Adder 83: Subtractor 84: Second voltage controller 90: Second upper voltage control circuit 91: First inverse U converter 92 : Subtractor 93: second upper control amplifier 100: third lower voltage control circuit 101: second reference voltage vector setter 102: adder 103: subtractor 104: third voltage controller 110: third upper voltage control circuit 111: Inverse UM converter 112: Subtractor 113: Third upper control amplifier 120: Upper command vector 200: Positive feedback circuit 210: Adder 220: Voltage abnormality detection circuit 230: Switch 401: Inverter bridge 402: Coil 403: Capacitor 404: Resistor 406: Current command 407: Drive unit 408: Gate signal generator (PWM)
409: Amplifier 410: Current reference 411: Gain or / and phase adjustment 412: Coefficient setting circuit 413: Frequency calculation 414: dV / dI ^*
415: distortion change 416: frequency detection 417: voltage effective detection 418: zero cross distortion detection 450: voltage detection 451: voltage relay 452: frequency relay 453: distortion relay 454: abnormality detection

Claims (3)

It has internal equivalent impedance when viewed from the AC terminal, converts the power from the DC voltage source into three-phase AC power according to the pulse width of the gate signal generated based on the PWM command, and outputs the three-phase AC power. A three-phase voltage type AC / DC conversion circuit for outputting the current from the AC terminal;
An output voltage vector obtained by converting the output from the three-phase voltage type AC / DC converter into a dq rotation coordinate space in which a component related to the amplitude of the output voltage is a d-axis component and a component related to a frequency difference is a q-axis component, and the AC A higher order command vector in the dq rotation coordinate space having an amplitude command value for the amplitude of the output voltage of the terminal as the d-axis component and a command value for the frequency as the q-axis component is input, and the input output voltage vector and the higher order command vector The upper voltage control circuit for outputting a voltage command vector generated so that the amplitude and frequency of the three-phase output voltage of the AC terminal approaches the command value by the upper command vector,
A positive feedback circuit that positively feeds back a dq rotational coordinate axis component of the output voltage vector to at least one dq rotational coordinate axis component of the upper command vector input to the upper voltage control circuit;
Based on a reference voltage vector that defines the amplitude and phase of the three-phase output voltage of the AC terminal, a vector based on the output voltage of the three-phase voltage type AC / DC converter circuit, and the voltage command vector from the upper voltage control circuit, A low-order voltage control circuit that outputs a signal generated as the PWM command so that the amplitude and phase of a three-phase output voltage approach a combined value of the reference voltage vector and the voltage command vector;
The generated value generated based on a reference frequency that defines the frequency of the three-phase output voltage of the AC terminal and the output of the three-phase voltage type AC / DC converter circuit in the q-axis component of the output voltage vector converted into the dq rotation coordinate space The generated value generated based on this is synchronized with the rotation angle of the conversion matrix for converting the output from the three-phase voltage type AC / DC conversion circuit into the dq rotation coordinate space and / or the rotation angle of the conversion matrix in the upper voltage control circuit. A frequency control circuit,
A voltage abnormality detection circuit that monitors the output voltage of the three-phase voltage type AC / DC conversion circuit and detects that the monitored voltage has deviated from a preset range as a voltage abnormality; and
A three-phase voltage type AC / DC converter comprising:
The three-phase voltage type AC / DC converter characterized in that the voltage abnormality detection circuit monitors an amplitude value of the output, a frequency of the output, or an amount correlated therewith. The gate signal stop function for stopping the gate signal in the three-phase voltage type AC / DC converter circuit and / or the three-phase voltage type AC / DC converter by a switch between the three-phase voltage type AC / DC converter circuit and the AC terminal. Inverter output stop means having a cutoff function to cut off the three-phase AC power from the circuit,
2. The three-phase voltage type AC / DC converter according to claim 1, wherein the inverter output stop unit stops the output of the three-phase AC power from the AC terminal when the voltage abnormality detection circuit detects a voltage abnormality. Conversion device. A switch for interrupting the positive feedback circuit and / or a positive feedback circuit stop means for setting the gain of the positive feedback circuit to 0,
The positive feedback circuit stop means performs positive feedback of the voltage output vector to the upper command vector performed by the positive feedback circuit after the inverter output stop means stops the output of the three-phase AC power from the AC terminal. The three-phase voltage type AC / DC converter according to claim 1, wherein the three-phase voltage type AC / DC converter is stopped.

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