JP5864241B2 - Power converter - Google Patents

Description

  The present invention relates to a grid-connected power converter, and in particular, detects a malfunction of a stand-alone output switch and the like, a load connected to the output side of the stand-alone output switch, The present invention relates to a technique for protecting a power conversion unit from damage or the like.

  FIG. 2 is a schematic configuration diagram showing a conventional grid interconnection power converter described in Patent Document 1 and the like.

  The grid interconnection power converter 10 used for power generation, power storage, and the like uses DC power supplied from a direct current (hereinafter referred to as “DC”) power source 20 such as a solar battery or a storage battery as alternating current (hereinafter referred to as “AC”). For example, the system output voltage V12 of AC200V is reversely flowed (that is, supplied) to the power system 21, or the independent output voltage V13 of AC100V is supplied to the load 22 such as a home electric machine. Device.

  This power converter 10 includes an input terminal 11 for inputting DC power supplied from a DC power supply 20, a system output terminal 12 for outputting a system output voltage V12 of AC200V to the power system 21, and a self-sustained output voltage V13 of AC100V. A self-supporting output terminal 13 for outputting to the load 22 is provided. A power conversion unit 14 is connected to the input terminal 11. The power conversion unit 14 converts DC power input from the input terminal 11 into AC power, generates a system output voltage V12 of AC200V, or an independent output voltage V13 of AC100V, and outputs it from the conversion output terminal 14a. It is a conversion circuit (inverter), and the first switch 15 and the second switch 16 are connected to the conversion output terminal 14a.

  The first switch 15 is connected between the conversion output terminal 14a and the system output terminal 12. The on / off state is switched by the switching signal S1, and the system output input from the conversion output terminal 14a in the on state. The voltage V12 is output to the system output terminal 12, and when it is in the OFF state, the conversion output terminal 14a and the system output terminal 12 are disconnected. The second switch 16 is connected between the conversion output terminal 14a and the self-sustained output terminal 13, and is switched on / off by the switching signal S2, and when it is in the on-state, the self-sustained output input from the conversion output terminal 14a. The voltage V13 is output to the self-supporting output terminal 13, and the conversion output terminal 14a and the self-supporting output terminal 13 are cut off when in the off state.

  A control unit 17 that controls the entire power conversion device is provided in the power conversion device 10. The control unit 17 outputs a drive signal (not shown) for controlling the operation of the power conversion unit 14 and switching signals S1 and S2 for switching on / off states of the first switch 15 and the second switch 16. It has a function.

  In the power conversion device 10 configured as described above, when DC power is supplied from the DC power supply 20, the power conversion unit 14 is operated and supplied with, for example, a drive signal (not shown) supplied from the control unit 17. A system output voltage V12 of AC200V is generated by switching a DC voltage of the DC power. The generated system output voltage V12 is output from the system output terminal 12 through the first switch 15 which is turned on by the switching signal S1 supplied from the control unit 17, and is reversely flowed to the AC200V power system 21. .

  When the grid output voltage V12 cannot flow backward to the power system 21 due to a system power failure or the like, the first switch 15 is turned off by the switching signal S1, and the power system 21 is disconnected from the conversion output terminal 14a. Next, under the control of the control unit 17, the power conversion unit 14 generates the AC 100 V self-sustained output voltage V 13, and the second switch 16 is turned on by the switching signal S 2 supplied from the control unit 17. Then, as indicated by a broken line arrow in FIG. 2, the generated self-sustained output voltage V13 is output to the self-sustained output terminal 13 through the second switch 16 and supplied to the load 22 of AC100V.

JP 2011-135767 A

  However, the conventional grid interconnection power converter 10 has the following problems (a) and (b).

  (A) In the grid interconnection power conversion device 10 used for power generation, power storage, and the like, when the grid output voltage V12 cannot be reversely flowed to the power grid 21 due to a grid power failure or the like, the power grid 21 is converted from the conversion output terminal 14a. And a self-sustaining operation function of supplying a self-sustained output voltage V13 to a load 22 connected to a self-supporting output terminal 13 provided separately. In this self-sustaining operation function, the system output terminal 12 and the self-sustained output terminal 13 must not be connected. Therefore, an interlock function is provided in the first switch 15 for system output and the second switch 16 for independent output. It corresponds. However, the power conversion unit 14 may generate a system output voltage V12 of AC200V even when the first switch 15 for system output is in an off state at the time of startup or the like. At this time, if the second switch 16 for self-sustained output is welded or malfunctions due to a failure of a circuit that drives the second switch 16, the system output voltage V12 generated in the power conversion unit 14 May be output to the self-supporting output terminal 13 as it is.

  For example, as described above, when the output voltage of the power conversion unit 14 (same as the interconnection output voltage V12) is AC200V and the use voltage of the load 22 on the independent output terminal 13 side is AC100V, it is connected to the independent output terminal 13. There is a risk of damaging the applied load 22. That is, since the second switch 16 is interlocked with the first switch 15, the system output terminal 12 and the self-supporting output terminal 13 are not turned on and connected at the same time. Since there is a current path (route) as indicated by the broken arrow in the middle, the load 22 may be damaged due to a malfunction of the second switch 16 or the like.

  (B) As another problem, there is a case where a power source is erroneously connected to the self-supporting output terminal 13. Since the power converter 14 is controlled differently when generating the AC 200V system output voltage V12 and when generating the AC 100V self-sustained output voltage V13, the power source such as the power system 21 is erroneously connected to the self-sustained output terminal 13. In such a case, there is a risk that the power conversion unit 14 may be stressed greatly, or the power conversion unit 14 may be damaged depending on circumstances.

  A power converter according to the present invention converts DC power into AC power, generates an AC grid output voltage or an AC independent output voltage lower than the grid output voltage, and outputs the AC output voltage from a conversion output terminal And a first switch, a second switch, a voltage detection unit, and a control unit.

  Here, the first switch is turned on by a first on signal, is electrically connected between the conversion output terminal and the system output terminal, and the system output voltage input from the conversion output terminal is supplied to the system The signal is output to the output terminal and turned off by the first off signal, and the conversion output terminal and the system output terminal are disconnected. The second switch is turned on / off in a complementary manner with respect to the first switch, is turned on by a second on signal, and conducts between the conversion output terminal and the self-supporting output terminal. The self-supporting output voltage input from the conversion output terminal is output to the self-supporting output terminal, and is turned off by a second off signal, and the conversion output terminal and the self-supporting output terminal are disconnected.

  The voltage detection unit detects whether an output side voltage of the second switch exceeds a threshold voltage set to be equal to or lower than the self-supporting output voltage, and the output side voltage of the second switch is the threshold value. When the voltage exceeds the voltage, a detection signal with voltage is output, and when the output side voltage of the second switch is equal to or lower than the threshold voltage, a detection signal without voltage is output. Further, the control unit generates and outputs the first on signal and the first off signal given to the first switch and the second on signal and the second off signal given to the second switch. And when the said detection signal with a voltage is input in the state which is outputting the said 2nd OFF signal, control which stops the operation | movement of the said power conversion part is performed.

In addition, the control unit detects the absence of voltage when the detection signal with the voltage is input while the second off signal is output, and when the second ON signal is output. When a signal is input, control to stop the operation of the power conversion unit is performed .

  According to the power conversion device of the present invention, there is a voltage output from the voltage detection unit in a state where the output side voltage of the second switch is detected by the voltage detection unit and the second off signal is output from the control unit. When the control unit inputs the detection signal, the operation of the power conversion unit is stopped by the control unit, so that the load connected to the self-supporting output terminal can be prevented from being damaged. Furthermore, when a power source such as a power system is erroneously connected to the self-supporting output terminal, the operation of the power conversion unit is stopped, so that an accident can be prevented.

In addition, when the control unit inputs a detection signal with voltage in a state of outputting the second off signal, and when the detection signal without voltage is input in a state of outputting the second on signal, Since the control for stopping the operation of the power conversion unit is performed, in addition to the detection of the failure of the second switch, the failure of the voltage detection unit can also be detected at the same time. Stop operation and prevent accidents.

FIG. 1 is a schematic configuration diagram showing a grid interconnection power converter according to a first embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing a conventional grid interconnection power converter. FIG. 3 is a schematic circuit diagram showing a configuration example of the grid interconnection power conversion device 30 of FIG. FIG. 4 is a circuit diagram illustrating a configuration example of the voltage detection unit 80 in FIGS. 1 and 3. FIG. 5 is a flowchart showing a schematic operation of the abnormality processing in the grid interconnection power conversion device 30 of FIGS. 1 and 3. FIG. 6 is a waveform diagram showing the operation of the abnormality process in the grid interconnection power conversion device 30 of FIGS. 1 and 3. FIG. 7 is a circuit diagram of a main part showing a configuration example of the grid interconnection power converter according to the second embodiment of the present invention. FIG. 8 is a circuit diagram of a main part showing a configuration example of the grid interconnection power conversion device according to the third embodiment of the present invention.

  Modes for carrying out the present invention will become apparent from the following description of the preferred embodiments when read in light of the accompanying drawings. However, the drawings are only for explanation and do not limit the scope of the present invention.

(Configuration of Example 1)
FIG. 1 is a schematic configuration diagram showing a grid interconnection power converter according to a first embodiment of the present invention.

  The grid interconnection power conversion device 30 converts DC power supplied from a DC power source 100 as a power generation facility including a solar cell, a storage battery, a fuel cell, wind power generation, and the like into AC power, for example, a system output of AC 200V This is a device that reversely flows the voltage V32 to the power system 101 or supplies a self-sustained output voltage V33 of AC100V, for example, lower than the system output voltage V32 to a load 102 such as a household electric machine.

  The power conversion device 30 includes an input terminal 31 for inputting DC power supplied from the DC power source 100, a system output terminal 32 for outputting a system output voltage V32 of AC200V to the power system 101, and a self-sustained output voltage V33 of AC100V. A self-supporting output terminal 33 that outputs to the load 102 is provided. A power conversion unit 40 is connected to the input terminal 31. The power conversion unit 40 is input from the input terminal 31 based on a plurality of drive signals Vg1 to Vg4 and the like that transition between a high level (hereinafter referred to as “H level”) and a low level (hereinafter referred to as “L level”). An inverter that converts DC power into AC power, generates a system output voltage V32 or a self-sustained output voltage V33, and outputs it from a conversion output terminal 41. The conversion output terminal 41 includes a first switch 71 and a second switch. 72 is connected.

  The first switch 71 is connected between the conversion output terminal 41 and the system output terminal 32. The on / off state is switched by the switching signal S1 including the first on signal S1a and the first off signal S1b. The system output voltage V32 input from the conversion output terminal 41 is output to the system output terminal 32 in the on state by the on signal S1a, and the conversion output terminal 41 and the system output terminal in the off state by the first off signal S1b. 32 is cut off, and is constituted by switch means such as a relay, a semiconductor switch, or a magnet conductor (MC). The second switch 72 is connected between the conversion output terminal 41 and the self-supporting output terminal 33, and is switched on / off by a switching signal S2 including a second on signal S2a and a second off signal S2b. In the ON state by the ON signal S2a, the independent output voltage V33 input from the conversion output terminal 41 is output to the independent output terminal 33. In the OFF state by the second OFF signal S2b, the conversion output terminal 41 and the independent output terminal 33 is cut off, and is constituted by switch means such as a relay, a semiconductor switch, or a magnet conductor (MC).

  A voltage detection unit 80 is connected to the output side of the second switch 72, and a control unit 90 is connected to the output side of the voltage detection unit 80. The voltage detector 80 detects whether or not the output-side voltage of the second switch 72 exceeds a threshold voltage Vt that is set to the self-sustained output voltage V33 or less, and as the detection signal S80, the voltage of the second switch 72 is detected. When the output side voltage exceeds the threshold voltage Vt, a detection signal S80a with voltage is output to the control unit 90, and when the output side voltage of the second switch 72 is less than or equal to the threshold voltage Vt, the detection signal S80b without voltage is output to the control unit. 90.

  For example, the control unit 90 supplies a first ON signal S1a, a first OFF signal S1b, and a second switch 72 as a switching signal S1 to be supplied to the first switch 71 by a program using a central processing unit (CPU). A second on signal S2a and a second off signal S2b are generated and output as the switching signal S2, and the drive signals Vg1 to Vg4 and the like to be given to the power conversion unit 40 are generated. The whole power converter 30 is controlled including the control of the switch 71 and the second switch 72. The control unit 90 further controls the abnormality processing during the operation of the power conversion unit 40 when the detection signal S80a with voltage is input in a state where the second off signal S2b is output to the power conversion unit 40. The first control function for stopping the generation of the drive signals Vg1 to Vg4 to be applied and stopping the operation of the power converter 40, and the detection signal S80b without voltage in the state where the second ON signal S2a is being output are input. In this case, a second control function for stopping generation of the drive signals Vg1 to Vg4 and the like given to the power conversion unit 40 and stopping the operation of the power conversion unit 40 is provided.

Further, the control unit 90 has an interlock function so that the first switch 71 and the second switch 72 are not turned on at the same time. Further, under the control of the control unit 90, the output voltage of the power conversion unit 40 is soft-started so as to increase from zero volts at the time of startup .

  In the configuration of the voltage detection unit 80 and the control unit 90, the power conversion unit 40 stops operating after the voltage detection unit 80 detects that the output voltage of the second switch 72 has exceeded the threshold voltage Vt. In the meantime, the operation delay time ta and the threshold voltage Vt of the voltage detection unit 80 and the control unit 90 are set so that the output side voltage of the second switch 72 (that is, the self-supporting output voltage V33) does not become an overvoltage. ing.

FIG. 3 is a schematic circuit diagram illustrating a configuration example of the grid interconnection power conversion device 30 of FIG. 1.
3 is a single-phase two-wire AC200V output with a single-phase two-wire AC200V output configuration, and the self-sustained output is a single-phase two-wire AC100V output. It is the composition of.

  The power converter 30 includes an input terminal 31 including a pair of + input terminal 31a and −input terminal 31b connected to the + electrode and −electrode of the DC power supply 100, and a pair of + system output terminal 32a and −system output terminal 32b. And a self-supporting output terminal 33 composed of a + self-supporting output terminal 33a and a −self-supporting output terminal 33b. The power conversion unit 40 is connected to the + input terminal 31a and the − input terminal 31b. The power conversion unit 40 includes a switch circuit 50 connected to the + input terminal 31 a and the − input terminal 31 b and a filter circuit 60 connected to the output side of the switch circuit 50.

  The switch circuit 50 switches the DC voltage of the DC power source 100 input from the + input terminal 31a and the − input terminal 31b by a plurality of drive signals Vg1 to Vg4 given from the control unit 90, and thereby the AC voltage (for example, AC 200V or For example, a plurality of switching transistors 51 to 54 made of an insulated gate bipolar transistor (IGBT) or the like are connected in a full bridge connection. The transistors 51 to 54 are turned on / off by the drive signals Vg1 to Vg4 supplied from the control unit 90 to convert the input DC voltage into an AC voltage. The parasitic diodes 51a to 54a are connected to the transistors 51 to 54 in an antiparallel state.

  The filter circuit 60 includes a pair of a + conversion output terminal 41a and a −conversion output terminal 41b by removing a high-frequency component of the AC voltage output from the switch circuit 50 and converting a sinusoidal AC voltage (for example, AC200V or AC100V). This is a circuit that outputs to the conversion output terminal 41, and is constituted by an LC filter including two reactors 61 and 62 and one capacitor 63.

  In the power converter 40, a step-up / step-down circuit composed of a DC / DC converter (not shown) may be provided between the + input terminal 31a and the − input terminal 31b and the switch circuit 50. This step-up / step-down circuit is a circuit for stepping up / stepping down the DC voltage of the DC power supply 100 input from the + input terminal 31 a and the − input terminal 31 b to a predetermined DC voltage.

  The first switch 71 includes a switching contact 71a connected between the + conversion output terminal 41a and the + system output terminal 32a, and a switching contact connected between the −conversion output terminal 41b and the −system output terminal 32b. 71b, and the two switching contacts 71a and 71b are simultaneously turned on / off by a switching signal S1 including a first on signal S1a and a first off signal S1b.

  Further, the second switch 72 is connected between the switching contact 72a connected between the + conversion output terminal 41a and the + self-supporting output terminal 33a, and between the −conversion output terminal 41b and the −self-supporting output terminal 33b. Switching contacts 72b, and the two switching contacts 72a and 72b are simultaneously turned on / off by a switching signal S2 including a second on signal S2a and a second off signal S2b.

FIGS. 4A and 4B are circuit diagrams showing a configuration example of the voltage detection unit 80 in FIGS. 1 and 3.
The voltage detector 80 shown in FIG. 4A includes two voltage dividing resistors 81 and 82 connected in series between the + independent output terminal 33a and the −independent output terminal 33b, and one voltage dividing resistor 82. The resistor 83 and the photocoupler 84 are connected in parallel to each other. The photocoupler 84 includes a bidirectional light emitting element for AC input (for example, a pair of light emitting diodes connected in antiparallel) 84a and a light receiving element (for example, phototransistor) 84b connected in series to the resistor 83. And is constituted by.

  In the voltage detector 80 of FIG. 4A, when an AC voltage exceeding the threshold voltage Vt is generated between the + independent output terminal 33a and the −independent output terminal 33b, the AC voltage is divided into voltage dividing resistors 81 and 82. And the current flows to the light emitting diode 84 a in the photocoupler 84 through the resistor 84. As a result, the light emitting diode 84a emits light and the phototransistor 84b is turned on, and a detection signal S80a with voltage (for example, an H level signal of several volts) is output from the phototransistor 84b as the detection signal S80. . When the AC voltage between the + self-supporting output terminal 33a and the −self-supporting output terminal 33b is equal to or lower than the threshold voltage Vt, the light emitting diode 84a in the photocoupler 84 does not emit light, so that the detection signal S80 is output from the phototransistor 84b. A detection signal S80b without voltage (for example, an L level signal) is output.

  The voltage detector 80 shown in FIG. 4B is configured by a step-down transformer 85. The step-down transformer 85 includes a primary winding 85a and a secondary winding 85b that are connected between a + independent output terminal 33a and a −independent output terminal 33b.

  In the voltage detector 80 of FIG. 4B, when an AC voltage exceeding the threshold voltage Vt is generated between the + independent output terminal 33a and the −independent output terminal 33b, the secondary winding 85b of the transformer 85 A detection signal S80a with voltage (for example, an H level signal of several volts) is output as the detection signal S80. When the AC voltage between the + self-supporting output terminal 33a and the −self-supporting output terminal 33b is equal to or lower than the threshold voltage Vt, the detection signal S80b without voltage is detected as the detection signal S80 from the secondary winding 85b of the transformer 85 (for example, , L level signal) is output.

(Normal operation of Example 1)
1 and FIG. 3, when DC power is supplied from the DC power supply 100, the power conversion unit 40 causes the drive signals Vg1 to Vg4 having a large duty ratio supplied from the control unit 90 to be supplied to the power conversion unit 40. Thus, the transistors 51 to 54 in the switch circuit 50 are turned on / off, and the supplied DC voltage of the DC power is converted into an AC voltage. A high frequency component is removed from the converted AC voltage by the filter circuit 60 to generate a sinusoidal AC system output voltage V32 of AC 200V, which is output from the + conversion output terminal 41a and the + system output terminal 32a of the conversion output terminal 41. . The system output voltage V32 of AC200V that is output passes through the switching contacts 71a and 71b of the first switch 71 that is turned on by the first on signal S1a of the switching signal S1 supplied from the control unit 90, and the system output terminal 32 Are output from the + system output terminal 32a and the −system output terminal 32b and are reversely flowed to the AC200V power system 101.

  At this time, due to the interlock function of the control unit 90, the contacts 72a and 72b of the second switch 72 are turned off, and the + conversion output terminal 41a and the + system output terminal 32a of the conversion output terminal 41 are independently output. The + self-supporting output terminal 33a and the -self-supporting output terminal 33b of the terminal 33 are disconnected.

  When the system output voltage V32 cannot flow backward to the power system 101 due to a system power failure or the like, the switching contacts 71a and 71b of the first switch 71 are turned off by the first off signal S1b of the switching signal S1, and the conversion output The power system 101 is disconnected from the + conversion output terminal 41a and the −conversion output terminal 41b of the terminal 14a. Next, the drive signals Vg1 to Vg4 having a small duty ratio are supplied from the control unit 90 to the power conversion unit 40, the transistors 51 to 54 in the switch circuit 50 are turned on / off, and the DC supplied from the DC power supply 100 is supplied. The voltage is converted to an AC voltage. A high frequency component is removed from the converted AC voltage by the filter circuit 60 to generate a sinusoidal free-standing output voltage V33 of AC100V.

  Thereafter, the contacts 72a and 72b of the second switch 72 are turned on by the second on signal S2a of the switching signal S2 supplied from the control unit 90, and the + conversion output terminal 41a and the + system output of the conversion output terminal 41 are turned on. The AC100V self-sustained output voltage V33 output from the terminal 32a is output to the + self-sustained output terminal 33a and the −self-sustained output terminal 33b of the self-sustained output terminal 33 through the contacts 72a and 72b of the second switch 72, and to the load 102. Supplied.

(Abnormality processing of Example 1)
FIG. 5 is a flowchart showing a schematic operation of the abnormality process in the grid interconnection power conversion device 30 of FIGS. 1 and 3.

  During the operation of the grid interconnection power converter 30, the following abnormality process is performed under the control of the control unit 90.

  In step ST1 of FIG. 5, when the abnormality process is started under the control of the control unit 90, the process proceeds to step ST2. At this time, the voltage detector 80 detects whether or not the output side voltage of the second switch 72 exceeds the threshold voltage Vt, and when the output side voltage of the second switch 72 exceeds the threshold voltage Vt. The detection signal S80a with voltage is output to the control unit 90. When the output side voltage of the second switch 72 is equal to or lower than the threshold voltage Vt, the detection signal S80b without voltage is output to the control unit 90.

  In step ST2, the control unit 90 determines whether the detection signal S80 output from the voltage detection unit 80 is the detection signal S80a with voltage or the detection signal S80b without voltage, and the determination result is that there is a voltage. In the case of the detection signal S80a (Yes), the process proceeds to step ST3, and in the case of the detection signal S80b without voltage (No), the process proceeds to step ST4.

  In step ST3, the control unit 90 determines whether or not the second off signal S2b is being given to the second switch 72, and when the determination result is giving the second off signal S2b (Yes) ), The second switch 72 is out of order (for example, welding of the contacts 72a and 72b, failure of a circuit (not shown) that drives the second switch 72, or the like), or the power source of the power system 101 is an independent output terminal. 33, the process proceeds to step ST5. On the other hand, when the second off signal S2b is not given (No), it is determined that the second switch 72 is normal or there is no erroneous connection. Return to step ST2. In step ST <b> 5, the control unit 90 stops generating the drive signals Vg <b> 1 to Vg <b> 4 to be supplied to the power conversion unit 40 and stops the operation of the power conversion unit 40.

  Further, when the process proceeds from step ST2 to step ST4, the control unit 90 determines whether or not the second on signal S72a is given to the second switch 72, and the determination result gives the second on signal S72a. If it is (Yes), the second switch 72 is faulty (for example, an OFF state due to a failure of the contacts 72a and 72b, a fault of a circuit (not shown) that drives the second switch 72), or the voltage detection unit 80. Is determined to be out of order, the process proceeds to step ST5, and the operation of the power converter 40 is stopped. When the determination result of step ST4 does not give the second on signal S7a (No), it is determined that the second switch 72 is normal, and the process returns to step ST2.

(Operation waveform of abnormality processing of Example 1)
FIG. 6 is a waveform diagram showing the operation of the abnormality processing in the grid interconnection power conversion device 30 of FIGS. 1 and 3.

  In FIG. 6, when the power conversion unit 40 is activated, the control unit 90 outputs the second off signal S2b. However, a failure (for example, welding of the contacts 72a and 72b of the second switch 72, second switching) The operation waveforms when the contacts 72a and 72b of the second switch 72 are in an ON state due to a failure of a circuit (not shown) that drives the device 72) are shown.

  In FIG. 6, the horizontal axis represents time (t), and the vertical axis represents potential. The self-supporting output voltage V33 of the first embodiment is a solid line, the conventional self-supporting output voltage V13 is a broken line, the detection signal S80a with voltage and the detection signal S80b without voltage of the first embodiment are solid lines, and there is an overvoltage of the comparative example Detection signals S80a-1 are indicated by broken lines. Vt is a threshold voltage of the first embodiment, Vt1 is a threshold voltage of overvoltage detection of the comparative example, and ta is an operation delay time of the voltage detection unit 80 and the control unit 90.

  When the power conversion unit 40 according to the first embodiment is activated at time t1 in FIG. 6, the self-sustained output voltage V33 output from the power conversion unit 40 is soft-started from AC0V and increases. At time t2, the voltage detector 80 detects that the self-sustained output voltage V33 exceeds the threshold voltage Vt1, and outputs a detection signal S80a (H level) with voltage to the controller 90. Then, since the control unit 90 stops generating the drive signals Vg1 to Vg4 supplied to the power conversion unit 40, the power conversion unit 40 at time t3 when the operation delay time ta of the voltage detection unit 80 and the control unit 90 has elapsed. Is stopped, and the rise of the independent output voltage V33 stops at AC 100V, and then the independent output voltage V33 falls. When the self-sustained output voltage V33 drops to the threshold voltage Vt at time t4, the voltage detection unit 80 outputs a no-voltage detection signal S80b (L level) to the control unit 90. Thereafter, the independent output voltage V33 becomes AC0V.

  On the other hand, in the conventional power converter 10 shown in FIG. 2, since the operation of the power converter 14 does not stop at time t3, the self-sustained output voltage V13 output from the power converter 14 exceeds AC 100V. It will rise to AC200V. For this reason, the load 22 for AC 100V may be damaged.

  In order to prevent this, as a comparative example, for example, in the power conversion device 10 of FIG. 2, an overvoltage detection circuit (not shown) having the overvoltage detection threshold voltage Vt1 shown in FIG. 6 on the output side of the second switch 16. When the self-sustained output voltage V13 exceeds the threshold voltage Vt1, it is conceivable that the operation of the power converter 14 is stopped by the overvoltage detection signal S80a-1 output from the overvoltage detection circuit. However, as shown in FIG. 6, the threshold voltage Vt1 needs to be set to a voltage higher than AC100V in order to enable a self-sustained output of AC100V during normal operation. Therefore, at time t5 after time t4 in FIG. 6, an overvoltage detection circuit S80a-1 with an overvoltage is output from an unillustrated overvoltage detection circuit, and then the operation of the power conversion unit 14 is stopped, so that the independent output voltage V13 is The voltage will rise to a voltage exceeding AC 100V, and the load 22 for AC 100V cannot be prevented from being damaged, and the configuration as in the comparative example cannot be adopted.

  Therefore, in order to solve such a problem, in the first embodiment, since the operation of the power conversion unit 40 is stopped at time t3, the increase of the independent output voltage V33 is suppressed to 100V AC or less, and the AC 100V Therefore, it is possible to accurately prevent the load 102 from being damaged.

(Effect of Example 1)
According to the first embodiment, there are the following effects (1) to (4).

  (1) In the power conversion device 30 with the built-in self-sustained output function having different voltages, the self-sustained output voltage V33 on the output side of the second switch 72 is detected by the voltage detector 80, and the second off signal S2b is received from the controller 90. When the control unit 90 inputs the detection signal S80a with voltage output from the voltage detection unit 80 in the output state, the operation of the power conversion unit 40 is performed by the first control function of the control unit 90. Like to stop. Thereby, breakage of the load 102 for AC100V can be prevented accurately. Furthermore, when a power source such as the power system 101 is erroneously connected to the self-supporting output terminal 33, an accident of the power conversion unit 40 can be prevented.

  (2) When the control unit 90 inputs the detection signal S80b without voltage output from the voltage detection unit 80 in a state where the control unit 90 outputs the second on signal S2a, Since the second control function determines that the second switch 72 or the voltage detector 80 is out of order and the operation of the power converter 40 is stopped, an accident can be prevented.

  The controller 90 may be configured not to be provided with the second control function. In this case, only the effect (1) is obtained. Therefore, if the control unit 90 is provided with the second control function, it is determined that the second switch 72 or the voltage detection unit 80 is out of order and the operation of the power conversion unit 40 is stopped, so that an accident can be prevented. More preferable.

  (3) Although the effect can be obtained with the overvoltage detection circuit of the comparative example, it is difficult to set the threshold voltage Vt1 for overvoltage detection, and the overvoltage is supplied to the load 22 until the overvoltage is detected and the power conversion unit 14 is stopped. Is a problem. In addition, there is a problem that detection is not possible even when a power supply of the same voltage is connected to the self-supporting output terminal 13. On the other hand, in the first embodiment, since the voltage detector 80 detects only the presence or absence of the output side voltage of the second switch 72, there is no problem as in the comparative example.

  (4) As shown in FIGS. 4A and 4B, the voltage detector 80 can be realized with an inexpensive configuration such as the voltage dividing resistors 81 and 82 and the photocoupler 84 or the transformer 85.

  FIG. 7 is a circuit diagram of a main part showing a configuration example of the grid interconnection power conversion device according to the second embodiment of the present invention. Elements common to the elements in FIG. Is attached.

  In the grid interconnection power conversion device 30A of the second embodiment, the power conversion unit 40 including the filter circuit 60 similar to that of the first embodiment is a single-phase three-wire AC200V output having a single-phase two-wire AC200V output configuration, and is independent. The output is a single-phase two-wire AC100V output.

  As in the first embodiment, the + conversion output terminal 41a and the − conversion output terminal 41b on the output side of the filter circuit 60 are connected to the + system output terminal 32a and the + system output terminal 32a via the first switch 71 having switching contacts 71a and 71b. -System output terminal 32b is connected. Between the + system output terminal 32a and the newly added grounding system output terminal 32c, an AC100V power system 101a is connected, and the -system output terminal 32b and the grounding system output terminal 32c Between them, an AC 100V power system 101b is also connected. Further, as in the first embodiment, the + conversion output terminal 41a and the −conversion output terminal 41b are connected to the + independent output terminal 33a and the −independent output terminal 33b through the second switch 72 having the switching contacts 72a and 72b. Is connected. As in the first embodiment, a load of 100 VAC is connected between the + independent output terminal 33a and the −independent output terminal 33b, and the voltage detection unit 80 is connected to the + independent output terminal 33a and the −independent output terminal 33b. Is connected.

  In the power conversion device 30 </ b> A having such a configuration, when the power conversion unit 40 operates, a single-phase AC 200 V is output from the power conversion unit 40, and the two AC 100 V power systems 101 a and 101 b are connected via the first switch 71. The power converter 30 according to the first embodiment can provide substantially the same operations and effects.

  FIG. 8 is a circuit diagram of a main part showing a configuration example of the grid interconnection power conversion device according to the third embodiment of the present invention. Elements common to the elements in FIG. Is attached.

  In the grid interconnection power conversion device 30B of the third embodiment, the power conversion unit 40B including the three-phase filter circuit 60B different from the first embodiment is a three-phase three-wire AC200V output configuration having a three-phase three-wire AC200V output configuration. Thus, the self-supporting output is configured as a single-phase two-wire AC100V output.

  The three-phase filter circuit 60B in the power conversion unit 40B is configured by an LC filter having reactors 61, 62, and 64 for each phase and capacitors 63a, 63b, and 63c between the phases. Three conversion output terminals 41a, 41b, and 41c on the output side of the filter circuit 60B are connected to three + through three first switches 71B having three switching contacts 71a, 71b, and 71c different from those in the first embodiment. A system output terminal 32a, a −system output terminal 32b, and a ground system output terminal 32c are connected. Three AC 200 V power systems 101-1, 101-2, and 101-3 are connected between the three system output terminals 32a, 32b, and 32c, respectively.

  Further, as in the first embodiment, the + conversion output terminal 41a and the −conversion output terminal 41b are connected to the + independent output terminal 33a and the −independent output terminal 33b through the second switch 72 having the switching contacts 72a and 72b. Is connected. As in the first embodiment, a load of 100 VAC is connected between the + independent output terminal 33a and the −independent output terminal 33b, and the voltage detection unit 80 is connected to the + independent output terminal 33a and the −independent output terminal 33b. Is connected.

  In the power conversion device 30B having such a configuration, when the power conversion unit 40B operates, a three-phase AC200V is output from the power conversion unit 40B, and the AC200V between the phases is output via the first switch 71B for three phases. The power is supplied to each of the power systems 101-1, 101-2, and 101-3, and substantially the same operations and effects as the power conversion device 30 of the first embodiment can be achieved.

(Modification)
The present invention is not limited to the above-described embodiments, and various usage forms and modifications are possible.
For example, the power conversion units 40 and 40B may be changed to a circuit configuration other than those shown in FIGS. The voltage detector 80 may be changed to a circuit configuration other than that shown in FIG.

30, 30A, 30B Grid interconnection power converter 40, 40B Power converter 50 Switch circuit 60, 60B Filter circuit 71, 71B First switch 72 Second switch 80 Voltage detector 90 Controller 100 DC power supply 101, 101-1, 101-2, 101-3 AC200V power system 101a, 101b AC100V power system 102 AC100V load

Claims (6)

A power converter that converts DC power into AC power, generates an AC grid output voltage, or an AC self-sustained output voltage lower than the grid output voltage and outputs it from the conversion output terminal; and
The first on signal is turned on, the conduction between the conversion output terminal and the system output terminal is conducted, the system output voltage inputted from the conversion output terminal is outputted to the system output terminal, and the first off signal A first switch that is in an off state by which the connection between the conversion output terminal and the system output terminal is interrupted;
The on / off state is complementarily switched with respect to the first switch, and is turned on by the second on signal. The conduction between the conversion output terminal and the self-supporting output terminal is established and input from the conversion output terminal. A second switch that outputs the generated self-supporting output voltage to the self-supporting output terminal, is turned off by a second off signal, and disconnects between the conversion output terminal and the self-supporting output terminal;
It is detected whether the output side voltage of the second switch exceeds a threshold voltage set to be equal to or lower than the self-sustained output voltage, and the voltage when the output side voltage of the second switch exceeds the threshold voltage A voltage detection unit that outputs a detection signal with a voltage, and outputs a detection signal with no voltage when the output-side voltage of the second switch is equal to or lower than the threshold voltage;
Generating and outputting the first on signal and the first off signal applied to the first switch and the second on signal and the second off signal applied to the second switch; When the detection signal with the voltage is input in a state where the power is output, a control unit that performs control to stop the operation of the power conversion unit,
Bei to give a,
The controller is
When the detection signal with voltage is input while the second off signal is being output, and when the detection signal without voltage is input with the second on signal being output, A power conversion apparatus that performs control to stop the operation of the power conversion unit. The power conversion device according to claim 1, wherein the first switch and the second switch are provided with an interlock function so that the first switch and the second switch are not turned on at the same time. The power converter according to claim 1 or 2, wherein the first switch and the second switch are configured by switch means including a relay, a semiconductor switch, or a magnet conductor, respectively. For the output voltage of the power converter, a soft start that rises from zero volts at the time of startup is performed,
After the voltage detection unit detects that the output side voltage of the second switch exceeds the threshold voltage and before the power conversion unit stops operation, the second switch 4. The operation delay time of the voltage detection unit and the control unit and the threshold voltage are set so that the output side voltage does not become an overvoltage. 5. Power converter. 5. The power conversion according to claim 1, wherein in the control unit, the control for stopping the operation of the power conversion unit is executed by program control using a central processing unit. apparatus. 6. The power converter according to claim 1, wherein the DC power is supplied from a power generation facility including a solar cell, a storage battery, a fuel cell, and a wind power generator.

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