JP2023114305A - Grid connection device and power conditioner - Google Patents

Abstract

To simplify and downsize a configuration.SOLUTION: A grid connection device includes an insulated DC/DC conversion unit that converts DC power supplied from a DC power supply into DC power of a first voltage, an inverter unit that converts the DC power of the first voltage converted by the DC/DC conversion unit into AC power that can be connected to a grid, and supplies the AC power to an AC load, an AC/DC conversion unit that rectifies AC power supplied from a system power supply into DC power, and converts the rectified DC power into DC power of a second voltage which is a power supply for control, a power supply line for DC power of the first voltage converted by the DC/DC conversion unit, and a connection unit that performs connection of a power supply line for the rectified DC power rectified by the AC/DC conversion unit.SELECTED DRAWING: Figure 1

Description

The present invention relates to a system interconnection device and a power conditioner.

In recent years, there has been known a system interconnection device that enables power to be supplied to an AC load from both AC power generated from a DC power supply such as a solar battery whose output voltage fluctuates and AC power supplied by a system power supply. (See, for example, Patent Document 1).

JP-A-2017-55508

By the way, in the above-described conventional system interconnection device, it is necessary to always supply a DC control power source for controlling the whole. In a conventional grid interconnection device, a DC/DC conversion unit that generates control power from the DC power supply and a control power supply from the system power supply so that operation can be performed even if either the DC power supply or the system power supply is lost. and an AC/DC converter that generates Therefore, there is a problem that the configuration and external shape of the system interconnection device become large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a system interconnection device and a power conditioner that can be simplified in configuration and reduced in size.

In order to solve the above problem, one aspect of the present invention provides an insulated DC/DC conversion unit that converts DC power supplied from a DC power supply into DC power of a first voltage, and the DC/DC conversion unit converts the converted DC power of the first voltage into AC power that can be connected to the grid, and an inverter unit that supplies the AC load to the AC load; An AC/DC conversion unit that converts rectified DC power into DC power of a second voltage that is a power supply for control, a power supply line of the DC power of the first voltage converted by the DC/DC conversion unit, and the AC and a connecting portion for connecting to a power supply line of the rectified DC power rectified by the /DC converting portion.

Further, according to one aspect of the present invention, in the above system interconnection device, the AC/DC conversion unit includes a synchronous rectification unit that rectifies AC power supplied from the system power supply, and the connection unit includes the inverter When the synchronous rectification unit operates with the output line of the unit and the power supply line of the system power supply connected, the power supply line of the DC power of the first voltage and the power supply line of the rectified DC power and a switch that cuts off the connection between the

Further, according to one aspect of the present invention, in the grid interconnection device described above, the connection unit includes the switch having a body diode and the power supply line for the DC power of the first voltage to the power supply line for the rectified DC power. and a connection diode arranged in a forward direction when DC power is supplied.

Further, according to one aspect of the present invention, in the grid interconnection device described above, the synchronous rectification unit includes an upper diode and a lower switching element connected in series, and the connection diode is connected to a low potential side. A first diode arranged in a line and a second diode arranged in a connection line on the high potential side, wherein the switch is arranged in the connection line on the low potential side.

Further, according to one aspect of the present invention, in the grid interconnection device described above, the synchronous rectification unit includes an upper switching element and a lower switching element connected in series, and the switch is connected to a low potential side. It is characterized by including a first switch arranged on the line and a second switch arranged on the connection line on the high potential side.

Further, one aspect of the present invention includes an insulated DC/DC converter that converts DC power supplied from a DC power supply into DC power of a first voltage, and the first DC/DC converter converted by the DC/DC converter. The inverter unit converts DC power with a voltage of 100 to AC power that can be connected to the grid and supplies it to the AC load. An AC/DC conversion unit that converts the DC power of a second voltage as a power source, a power supply line of the DC power of the first voltage converted by the DC/DC conversion unit, and the AC/DC conversion unit for rectification and a connection part for connecting the power supply line of the rectified DC power.

According to the present invention, the grid interconnection device converts the DC power line of the first voltage converted from the DC power supply by the DC/DC converter and the DC power of the second voltage as the control power supply. Since the AC/DC conversion unit has a connection unit for connecting the power supply line of the rectified DC power rectified from the system power supply, the AC/DC conversion unit generates control power from both the DC power supply and the system power supply. be able to. Therefore, the system interconnection device does not need to include both a DC/DC converter that generates control power from a DC power supply and an AC/DC converter that generates control power from a system power supply, simplifying the configuration. can be made smaller and smaller.

1 is a block diagram showing an example of a power conditioner according to a first embodiment; FIG. 4 is a flow chart showing an example of the operation of the power conditioner according to the first embodiment; FIG. 4 is a diagram for explaining an example of the operation when the power conditioner according to the first embodiment is interconnected; 1 is a block diagram showing an example of a conventional power conditioner; FIG. FIG. 7 is a block diagram showing an example of a power conditioner according to a second embodiment; FIG.

A system interconnection device according to an embodiment of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing an example of a power conditioner 1 according to the first embodiment.
As shown in FIG. 1, the power conditioner 1 includes a DC/DC conversion section 10, an inverter section 20, an AC/DC conversion section 30, a connection section 40, a control section 50, and a capacitor C1. there is In addition, in this embodiment, the power conditioner 1 is an example of a system interconnection device that can be system-connected to the commercial power supply 3 .

The DC/DC converter 10 is, for example, an insulated DC/DC converter, and converts DC power supplied from the DC power supply 2 into DC power of voltage V1 (first voltage).
Here, the DC power supply 2 is, for example, a power source such as a solar cell or a fuel cell.
The DC/DC conversion section 10 includes an input filter 11 , an inverter circuit 12 , a transformer 13 , a synchronous rectification section 14 and a conversion control section 15 .

The input filter 11 is, for example, a low-pass filter circuit, which reduces noise in the DC power supplied from the DC power supply 2 and smoothes the noise.

The inverter circuit 12 generates three-phase AC signals (eg, U-phase AC signal, V-phase AC signal, W-phase AC signal) from the DC power supplied from the DC power supply 2 . The inverter circuit 12 includes three sets of two switching elements connected in series between the two power lines of the DC power supply 2 . In the inverter circuit 12, each switching element is switched under the control of the conversion control unit 15, which will be described later, to generate a three-phase AC signal. Here, the switching element is, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The inverter circuit 12 supplies the generated three-phase AC signal to the transformer 13 .

The transformer 13 includes, for example, three transformers, and converts the 3-phase AC signal generated by the inverter circuit 12 into a 3-phase AC signal with a predetermined voltage. The transformer 13 supplies the AC signal whose voltage is converted to the synchronous rectification section 14 .

The synchronous rectifier 14 rectifies the three-phase AC signal supplied from the transformer 13 into DC power of voltage V1 (first voltage). The synchronous rectification unit 14 includes three sets of two switching elements connected in series between the power line L1 on the high potential side and the power line L2 on the low potential side. Here, the switching element is, for example, a MOSFET. The synchronous rectification unit 14 switches each switching element under the control of the conversion control unit 15, which will be described later, to generate DC power of voltage V1 obtained by rectifying the three-phase AC signal.

The conversion control unit 15 is, for example, a processor including a CPU (Central Processing Unit), and controls the DC/DC conversion unit 10 as a whole. The conversion control section 15 controls each section of the DC/DC conversion section 10 based on a control command from the control section 50, which will be described later. The conversion control unit 15 controls switching of each MOSFET of the inverter circuit 12 and each MOSFET of the synchronous rectification unit 14, for example, so that the voltage output from the synchronous rectification unit 14 becomes the voltage V1.

Capacitor C1 is a smoothing capacitor that is arranged between power supply line L1 and power supply line L2 and smoothes the output voltage (voltage V1) of DC/DC converter 10 .

The inverter unit 20 converts the DC power of the voltage V1 converted by the DC/DC conversion unit 10 into AC power that can be connected to the grid, and supplies the AC power to an AC load (not shown). The inverter unit 20 generates an AC signal that is phase-synchronized with the commercial power supply 3 so that it can be interconnected to the commercial power supply 3 .
The inverter section 20 includes an inverter circuit 21 , a noise filter 22 , an independent relay 23 , a system relay 24 , an inverter control section 25 and a connection switch 42 .

The inverter circuit 21 generates a two-phase AC signal from the DC power of voltage V<b>1 supplied from the DC/DC conversion section 10 . The inverter circuit 21 includes two sets of two switching elements connected in series between two power supply lines of voltage V1 (between power supply line L1 and power supply line L2). The inverter circuit 21 switches each switching element under the control of an inverter control unit 25 to be described later, and generates an AC signal that can be connected to the commercial power supply 3 . Here, the switching element is, for example, a MOSFET. The inverter circuit 21 supplies the generated AC signal to the noise filter 22 .

The noise filter 22 is, for example, a filter circuit that allows an AC signal of the frequency of the commercial power supply 3 connected to the grid to pass through to reduce high-frequency noise. It is supplied to the relay 23 and the system relay 24 .

The isolation relay 23 is a relay switch for outputting an AC signal when the AC signal generated by the inverter circuit 21 is used for self-sustaining operation. The self-sustaining relay 23 supplies AC power to a connected load section (not shown) during self-sustaining operation. Connection of the independent relay 23 is controlled by the control of the inverter control unit 25, which will be described later.

The system relay 24 is a relay switch for outputting an AC signal when the AC signal generated by the inverter circuit 21 is connected to the system. The system relay 24 supplies AC power to a load section (not shown) connected to the commercial power supply 3 or sells the power to the commercial power supply 3 at the time of system interconnection. Connection of the system relay 24 is controlled by the control of the inverter control unit 25, which will be described later.

The connection switch 42 is a switch that connects between a DC power power line (power line L2) of voltage V1 and a rectified DC power power line (power line L4) of the AC/DC converter 30, which will be described later. Details of the connection switch 42 will be described later.

The inverter control unit 25 is, for example, a processor including a CPU, and controls the inverter unit 20 as a whole. The inverter control section 25 controls each section of the inverter section 20 based on a control command from the control section 50, which will be described later. For example, the inverter control unit 25 switches each MOSFET of the inverter circuit 21 so that the AC signal output by the inverter circuit 21 can be connected to the commercial power supply 3 (system interconnection is possible), and the independent relay 23 and the system relay 24 , and the connection switch 42 .

The AC/DC conversion unit 30 rectifies the AC power supplied from the commercial power supply 3, which is the system power supply, into DC power, and converts the rectified DC power into the DC power of voltage V2 (second voltage), which is the control power supply. Convert to The AC/DC converter 30 supplies the DC power of the converted voltage V2 to the controller 50 .

The AC/DC converter 30 includes a noise filter 31, a synchronous rectifier 32, a capacitor C2, an inverter circuit 33, a transformer 34, a synchronous rectifier 35, a conversion controller 36, and a connection diode 41 (41- 1, 41-2).

The noise filter 31 is, for example, a filter circuit that allows an AC signal having the frequency of the commercial power supply 3 to pass through and reduces high-frequency noise. supply to

The synchronous rectifier 32 rectifies the AC signal supplied from the commercial power supply 3 through the noise filter 31 into DC power (rectified DC power) of voltage V1 (first voltage). The synchronous rectification unit 32 includes two pairs of diodes 37 and switching elements 38 connected in series between the high-potential power line L3 and the low-potential power line L4. That is, the synchronous rectifier 32 includes upper diodes 37 (37-1, 37-2) and lower switching elements 38 (38-1, 38-2) connected in series. The synchronous rectification unit 32 switches each switching element 38 under the control of the conversion control unit 36, which will be described later, to generate DC power of voltage V1 obtained by rectifying the AC signal.

In this embodiment, the diode 37-1 and the diode 37-2 have the same configuration. explain.

Further, in the present embodiment, the switching element 38-1 and the switching element 38-2 have the same configuration. A switching element 38 will be described.

The diode 37-1 has an anode terminal connected to a node N1 connected to one of the output lines of the noise filter 31, and a cathode terminal connected to the high-potential power supply line L3.
The diode 37-2 has an anode terminal connected to the node N2 connected to the other output line of the noise filter 31, and a cathode terminal connected to the high-potential power supply line L3.

The switching element 38-1 is, for example, an N-type MOSFET. The switching element 38-1 has a source terminal connected to the low-potential power supply line L4 and a drain terminal connected to the node N1. A gate terminal (control terminal) of the switching element 38-1 is connected to a signal line for a control signal output from the conversion control section 36, which will be described later.

The switching element 38-2 is, for example, an N-type MOSFET. The switching element 38-2 has a source terminal connected to the low-potential power supply line L4 and a drain terminal connected to the node N2. A gate terminal (control terminal) of the switching element 38-2 is connected to a signal line for a control signal output from the conversion control section 36, which will be described later.
Switching of the switching element 38-1 and the switching element 38-2 is controlled by a conversion control unit 36, which will be described later.

Capacitor C2 is a smoothing capacitor that is arranged between power supply line L3 and power supply line L4 and smoothes the output voltage (voltage V1) of synchronous rectifier 32 .

The inverter circuit 33 generates an AC signal from the DC power supplied from the synchronous rectification section 32 . The inverter circuit 33 includes two switching elements connected in series between the two power lines of voltage V2 (between the power lines L3 and L4), and a capacitor C3. In the inverter circuit 33, each switching element is switched under the control of the conversion control unit 36, which will be described later, to generate an AC signal. Here, the switching element is, for example, a MOSFET. The inverter circuit 33 supplies the generated AC signal to the transformer 34 .
The capacitor C3 is arranged between the power line L4 and one end of the input terminal of the transformer 34 .

The transformer 34 converts, for example, the AC signal generated by the inverter circuit 33 into an AC signal with a predetermined voltage. The transformer 34 supplies the AC signal whose voltage is converted to the synchronous rectification section 35 .

The synchronous rectifier 35 rectifies the AC signal supplied from the transformer 34 into DC power of voltage V2 (second voltage). The synchronous rectifier 35 has two switching elements. The synchronous rectification unit 35 switches each switching element under the control of the conversion control unit 36, which will be described later, to generate DC power of voltage V2 by rectifying the AC signal. The synchronous rectification unit 35 supplies the rectified DC power of voltage V2 to the control unit 50 .

The conversion control unit 36 is, for example, a processor including a CPU, and controls the AC/DC conversion unit 30 as a whole. The conversion control section 36 controls each section of the AC/DC conversion section 30 based on a control command from the control section 50, which will be described later. The conversion control unit 36 controls switching of the switching element 38 of the synchronous rectification unit 32 so that the voltage output from the synchronous rectification unit 32 becomes the voltage V1, for example. Further, the conversion control unit 36 controls switching of each MOSFET of the inverter circuit 33 and each MOSFET of the synchronous rectification unit 35 so that the voltage output from the synchronous rectification unit 35 becomes the voltage V2, for example. The conversion control unit 36 controls switching of each MOSFET of the inverter circuit 33 and each MOSFET of the synchronous rectification unit 35 by, for example, the LLC method to generate the voltage V2.

The inverter circuit 33, the transformer 34, and the synchronous rectifier 35 function as an insulated DC/DC converter that converts the DC power of the voltage V1 into the DC power of the voltage V2.

The connection diode 41 is in the forward direction when supplying DC power from the DC power supply line (power supply line L1 and power supply line L2) of voltage V1 to the rectified DC power supply line (power supply line L3 and power supply line L4). are arranged as follows.

In the present embodiment, the connection diode 41-1 and the connection diode 41-2 will be described as the connection diode 41 when any connection diode provided in the power conditioner 1 is indicated or when they are not particularly distinguished.
Further, in the present embodiment, the connection diodes 41-1 and 41-2 and the connection switch 42 correspond to the connection section 40. FIG. That is, the connection unit 40 includes a connection diode 41-1, a connection diode 41-2, and a connection switch .

The connection diode 41-1 (first diode) supplies DC power from the DC power line (power line L1 and power line L2) of voltage V1 to the rectified DC power line (power line L3 and power line L4). It is arranged so that it is in the forward direction when The connection diode 41-1 has, for example, an anode terminal connected to the power line L4 and a cathode terminal connected to the power line L2 via the connection switch 42, respectively. The cathode terminal of the connection diode 41-1 is connected to the drain terminal of the connection switch 42. FIG. The connection diode 41-1 is arranged on the connection line on the low potential side.

The connection diode 41-2 (second diode) supplies DC power from the DC power supply line (power supply line L1 and power supply line L2) of voltage V1 to the rectified DC power supply line (power supply line L3 and power supply line L4). It is arranged so that it is in the forward direction when The connection diode 41-2 has, for example, an anode terminal connected to the power supply line L3 and a cathode terminal connected to the power supply line L1. The connection diode 41-2 is arranged on the connection line on the high potential side.

The connection switch 42 is, for example, an N-type MOSFET, and has a source terminal connected to the power supply line L2 and a drain terminal connected to the cathode terminal of the connection diode 41-1. That is, the connection switch 42 is arranged on the connection line on the low potential side.

A gate terminal (control terminal) of the connection switch 42 is connected to a signal line of a control signal output from the inverter control section 25, for example. When the synchronous rectification unit 32 operates with the output line of the inverter unit 20 and the power line of the commercial power supply 3 (system power supply) connected, the connection switch 42 connects the power line L2 of the DC power of the voltage V1. and the power supply line L4 for the rectified DC power.

The connection unit 40 connects a power line (power line L1 and power line L2) for DC power of voltage V1 converted by the DC/DC conversion unit 10 and a power line for rectified DC power (power line L2) rectified by the AC/DC conversion unit 30 (power line L2). line L3 and power line L4).

The control unit 50 is, for example, a processor including a CPU, and controls the power conditioner 1 in an integrated manner. The control unit 50 is supplied with the DC power of the voltage V2 output by the AC/DC conversion unit 30 and executes various control processes. The control unit 50 controls the DC/DC conversion unit 10, the inverter unit 20, the AC/DC conversion unit 30, and the connection unit 40, for example.

Next, operation of the power conditioner 1 according to this embodiment will be described with reference to the drawings.
First, referring to FIG. 1, the overall operation of the power conditioner 1 will be described.
The DC/DC conversion section 10 first converts the DC power output from the DC power supply 2 such as a solar cell or a fuel cell into DC power of voltage V1 and supplies the DC power to the inverter section 20 .

In the DC/DC conversion unit 10, the inverter circuit 12 converts the DC power output from the DC power supply 2 whose noise has been reduced by the input filter 11 into a three-phase AC signal. The inverter circuit 12 supplies the three-phase AC signal to the transformer 13, which then converts it into a three-phase AC signal with a predetermined voltage. The transformer 13 supplies the AC signal whose voltage is converted to the synchronous rectification section 14 .

Next, the synchronous rectification section 14 synchronously rectifies the AC signal whose voltage is converted by the transformer 13 and supplies the DC power of the voltage V1 to the inverter section 20 .
Next, the inverter circuit 21 of the inverter unit 20 converts the DC power of the voltage V1 into AC power that can be connected to the commercial power supply 3 , and supplies the AC power to the commercial power supply 3 via the system relay 24 . In addition, the inverter unit 20 supplies the AC power generated by the inverter circuit 21 to a load unit (not shown) that operates in a self-sustained manner via the self-sustaining relay 23 when the inverter unit 20 operates in a self-sustained manner.

Further, the AC/DC conversion unit 30 converts the AC power of the commercial power supply 3 into the DC power of the voltage V1, further converts the DC power of the voltage V1 into the DC power of the voltage V2, and sends the power to the control unit 50. supply. In the AC/DC conversion unit 30, the synchronous rectification unit 32 converts the AC power supplied from the commercial power supply 3 into the DC power of voltage V1, and furthermore, the inverter circuit 33 and the transformer 34, which are insulated DC/DC converters. , and the synchronous rectifier 35 convert the DC power of the voltage V1 into the DC power of the voltage V2.

Further, the connection unit 40 connects the DC power of the voltage V1 converted by the DC/DC conversion unit 10 to the power line (power line L3, power line L4). The AC/DC conversion unit 30 converts the DC power of the voltage V1 supplied from the connection unit 40 and converted by the DC/DC conversion unit 10 or the rectified DC power of the voltage V1 rectified by the synchronous rectification unit 32 into the DC power of the voltage V2. to generate

That is, for example, when the synchronous rectification unit 32 is stopped, the AC/DC conversion unit 30 converts the DC power of the voltage V1 converted by the DC/DC conversion unit 10 into the DC power of the voltage V2 to be supplied to the control unit 50. can be generated. For example, when the DC/DC conversion unit 10 is stopped, the AC/DC conversion unit 30 converts the rectified DC power of the voltage V1 rectified by the synchronous rectification unit 32 into the DC power of the voltage V2 to be supplied to the control unit 50. Power can be generated.

Next, control processing of the connection switch 42 in this embodiment will be described with reference to FIG.
FIG. 2 is a flow chart showing an example of the operation of the power conditioner 1 according to this embodiment. Here, control processing of the connection switch 42 of the connection unit 40 will be described.

As shown in FIG. 2, the inverter control unit 25 of the inverter unit 20 determines whether the power conditioner 1 is connected to the grid and the synchronous rectification unit 32 is in operation (step S101). When the power conditioner 1 is connected to the grid and the synchronous rectification unit 32 is in operation (step S101: YES), the inverter control unit 25 advances the process to step S102. Moreover, the inverter control part 25 advances a process to step S103, when the power conditioner 1 is not a system interconnection connection or the synchronous rectification part 32 is not operating (step S101: NO).

In step S102, inverter control unit 25 turns off connection switch 42 of connection unit 40 . That is, the connection switch 42 cuts off the connection by the connection part 40, as shown in FIG.

FIG. 3 is a diagram for explaining an example of the operation of the power conditioner 1 according to this embodiment when the system is interconnected.
In FIG. 3, when the connection switch 42 is in the ON state, the system relay 24 is in the ON state, the power conditioner 1 is connected to the grid connection, and the synchronous rectification unit 32 is in operation, the commercial power supply 3 A loop RP is formed in which the power supplied from is returned to the commercial power supply 3 again, and there is a possibility that a grid short circuit may occur.

Here, the loop RP includes from the commercial power supply 3, the noise filter 31, the switching element 38 on the lower side of the synchronous rectification section 32, the connection diode 41-1, the connection switch 42, the switching element on the lower side of the inverter circuit 21, the noise filter 22 , and a system relay 24 to return to the commercial power supply 3 .

In this case, the inverter control unit 25 turns off the connection switch 42 to disconnect the inverter unit 20 and the AC/DC conversion unit 30, thereby cutting the loop RP described above.
Returning to FIG. 2, after the process of step S102, the inverter control unit 25 returns the process to step S101.

In step S103, inverter control unit 25 turns on connection switch 42 of connection unit 40 . That is, the connection switch 42 brings the connection by the connection unit 40 into the connected state. After the process of step S103, the inverter control unit 25 returns the process to step S101.

As described above, the power conditioner 1 (system interconnection device) according to this embodiment includes the DC/DC conversion section 10, the inverter section 20, the AC/DC conversion section 30, and the connection section 40. The DC/DC converter 10 is an insulated DC/DC converter that converts DC power supplied from the DC power supply 2 into DC power of voltage V1 (first voltage). The inverter unit 20 converts the DC power of the voltage V1 converted by the DC/DC conversion unit 10 into AC power that can be connected to the grid, and supplies the AC power to an AC load (not shown). The AC/DC converter 30 rectifies AC power supplied from the commercial power supply 3 (system power supply) into DC power (DC power of voltage V1), and converts the rectified rectified DC power into voltage V2 (second power supply) which is a control power supply. 2 voltage) into DC power. The connection unit 40 connects a power line (power line L1 and power line L2) for DC power of voltage V1 converted by the DC/DC conversion unit 10 and a power line for rectified DC power (power line L2) rectified by the AC/DC conversion unit 30 (power line L2). line L3 and power line L4).

As a result, since the power conditioner 1 (system interconnection device) according to the present embodiment includes the connection unit 40, the AC/DC conversion unit 30 converts both the DC power supply 2 and the commercial power supply 3 (system power supply) into A power supply for control (DC power of voltage V2) can be generated.

4 is a block diagram showing an example of a conventional power conditioner 100. As shown in FIG.
As shown in FIG. 4, the conventional power conditioner 100 includes an insulated DC/DC conversion unit 110, an inverter unit 120, an AC/DC conversion unit 130, a DC/DC conversion unit 140, and a control unit 150. and The conventional power conditioner 100 includes both a DC/DC converter 140 that generates control power from the DC power supply 2 and an AC/DC converter that generates control power from the commercial power supply 3 (system power supply). I needed it. Here, the control power supply is a DC power supply that is supplied to the control unit 150 .

On the other hand, since the power conditioner 1 according to the present embodiment includes the connection unit 40, the DC/DC conversion unit 140 that generates control power from the DC power supply 2 like the conventional power conditioner 100 described above. , and the AC/DC converter 130 that generates control power from the commercial power supply 3 (system power supply). Therefore, the power conditioner 1 according to the present embodiment can have a simpler configuration and a smaller size than the conventional power conditioner 100 .

In addition, in this embodiment, the AC/DC conversion unit 30 includes a synchronous rectification unit 32 that rectifies AC power supplied from the commercial power supply 3 (system power supply). The connection unit 40 includes a connection switch 42 (switch). The connection switch 42 connects the output line of the inverter section 20 to the power line of the commercial power supply 3 (the system relay 24 is on), and when the synchronous rectification section 32 operates, the DC power of the voltage V1 is connected. and the power lines of the rectified DC power (power lines L3 and L4).

As a result, the power conditioner 1 according to the present embodiment can disconnect the loop RP shown in FIG. can. The power conditioner 1 according to the present embodiment can safely supply power to the control unit 50 and operate the power conditioner 1 safely, for example, when the system relay 24 is welded.

In addition, in the present embodiment, the connection unit 40 includes a connection switch 42 (switch) having a body diode and a forward direction when supplying DC power from the DC power supply line of voltage V1 to the rectified DC power supply line. and a connecting diode 41 arranged to

As a result, the power conditioner 1 according to the present embodiment prevents the reverse flow of power from the DC power of the voltage V1 of the AC/DC conversion unit 30 to the DC power of the voltage V1 of the DC/DC conversion unit 10 by the connection diode 41. can be prevented.

In addition, in this embodiment, the synchronous rectification section 32 includes an upper diode 37 and a lower switching element 38 that are connected in series. The connection diode 41 includes a connection diode 41-1 (first diode) and a connection diode 41-2 (second diode). The connection diode 41-1 (first diode) is arranged on the connection line on the low potential side (the connection line between the power supply line L2 and the power supply line L4). The connection diode 41-2 (second diode) is arranged on the connection line on the high potential side (the connection line between the power supply line L1 and the power supply line L2). The connection switch 42 is arranged on the connection line on the low potential side (the connection line between the power line L2 and the power line L4).

As a result, the power conditioner 1 according to the present embodiment arranges the connection switch 42 on the connection line on the low potential side (the connection line between the power supply line L2 and the power supply line L4) and on the connection line on the high potential side (the power supply line). connection line between the line L1 and the power line L3). Therefore, the power conditioner 1 according to this embodiment can be further simplified and miniaturized in configuration.

[Second embodiment]
Next, a power conditioner 1a according to a second embodiment will be described with reference to the drawings.
FIG. 5 is a block diagram showing an example of a power conditioner 1a according to the second embodiment. In this embodiment, a modification will be described in which the diode 37 on the upper side of the synchronous rectification section 32 is changed to a switching element 37a.

As shown in FIG. 5, the power conditioner 1a includes a DC/DC conversion section 10, an inverter section 20, an AC/DC conversion section 30a, a connection section 40a, a control section 50, and a capacitor C1. there is In addition, in this embodiment, the power conditioner 1a is an example of a system interconnection device that can be system-connected to the commercial power source 3 .
Further, in FIG. 5, the same reference numerals are assigned to the same components as in FIG. 1 described above, and the description thereof will be omitted.

The AC/DC conversion unit 30a rectifies the AC power supplied from the commercial power supply 3, which is the system power supply, into DC power, and converts the rectified DC power into the DC power of voltage V2 (second voltage), which is the control power supply. Convert to The AC/DC converter 30a supplies the DC power of the converted voltage V2 to the controller 50 .

The AC/DC converter 30a includes a noise filter 31, a synchronous rectifier 32a, a capacitor C2, an inverter circuit 33, a transformer 34, a synchronous rectifier 35, a conversion controller 36, and a connection diode 41 (41- 1, 41-2).

The synchronous rectifier 32a rectifies the AC signal supplied from the commercial power supply 3 through the noise filter 31 into DC power (rectified DC power) of voltage V1 (first voltage). The synchronous rectification unit 32a includes two sets of an upper switching element 37a and a lower switching element 38 connected in series between a high-potential power line L3 and a low-potential power line L4. ing. That is, the synchronous rectification section 32a includes upper switching elements 37a (37a-1, 37a-2) and lower switching elements 38 (38-1, 38-2) connected in series. In the synchronous rectifier 32a, each switching element (37a, 38) is switched under the control of the conversion controller 36 to generate DC power of voltage V1 by rectifying the AC signal.

In this embodiment, the diode 37-1 and the diode 37-2 have the same configuration. explain.

Further, in the present embodiment, the upper switching element 37a-1 and the switching element 37a-2 have the same configuration, and when an arbitrary upper switching element provided in the synchronous rectification unit 32a is shown, or no particular distinction is made In this case, the switching element 37a will be described.

The switching element 37a-1 is, for example, an N-type MOSFET. The switching element 37a-1 has a source terminal connected to the node N1 and a drain terminal connected to the power supply line L3 on the high potential side. A gate terminal (control terminal) of the switching element 37 a - 1 is connected to a signal line for a control signal output from the conversion control section 36 .

The switching element 37a-2 is, for example, an N-type MOSFET. The switching element 37a-2 has a source terminal connected to the node N2 and a drain terminal connected to the power supply line L3 on the high potential side. A gate terminal (control terminal) of the switching element 37 a - 2 is connected to a signal line for a control signal output from the conversion control section 36 .
Switching of the switching element 37 a and the switching element 38 is controlled by the conversion control section 36 .

Further, in this embodiment, the connection diode 41-1, the connection diode 41-2, the connection switch 42-1, and the connection switch 42-2 correspond to the connection portion 40a. That is, the connection section 40a includes connection diodes 41-1 and 41-2, and connection switches 42-1 and 42-2. In this embodiment, the connection switches 42 include a connection switch 42-1 (first switch) arranged on the low potential side connection line and a connection switch 42-2 (second switch) arranged on the high potential side connection line. switches).

The connection switch 42-1 is a switch that connects between the DC power line (power line L2) of the voltage V1 and the rectified DC power line (power line L4) of the AC/DC converter 30a.
The connection switch 42-1 is, for example, an N-type MOSFET, and has a source terminal connected to the power supply line L2 and a drain terminal connected to the cathode terminal of the connection diode 41-1. That is, the connection switch 42-1 is arranged on the connection line on the low potential side.

A gate terminal (control terminal) of the connection switch 42-1 is connected to a signal line for a control signal output from the inverter control section 25, for example. The connection switch 42-1 connects the output line of the inverter section 20 to the power line of the commercial power supply 3 (system power supply), and when the synchronous rectification section 32a operates, the DC power supply of the voltage V1 is connected. The connection between the line L2 and the power line L4 for the rectified DC power is cut off.

The connection switch 42-2 is a switch that connects between the DC power line (power line L1) of the voltage V1 and the rectified DC power line (power line L3) of the AC/DC converter 30a.
The connection switch 42-2 is, for example, an N-type MOSFET, and has a source terminal connected to the power supply line L1 and a drain terminal connected to the cathode terminal of the connection diode 41-2. That is, the connection switch 42-2 is arranged on the connection line on the high potential side.

A gate terminal (control terminal) of the connection switch 42-2 is connected to a signal line for a control signal output from the inverter control section 25, for example. The connection switch 42-2 connects the output line of the inverter section 20 to the power line of the commercial power supply 3 (system power supply), and when the synchronous rectification section 32a operates, the DC power supply of the voltage V1 is connected. The connection between the line L1 and the power line L3 for the rectified DC power is cut off.

Also, in the present embodiment, since other configurations are the same as those of the above-described first embodiment, description thereof will be omitted here.

As described above, the power conditioner 1a according to the present embodiment includes the DC/DC conversion section 10, the inverter section 20, the AC/DC conversion section 30a, the connection section 40a, and the control section 50. .
As a result, the power conditioner 1a according to the present embodiment can achieve the same effects as those of the first embodiment described above, and can be simplified and miniaturized in configuration.

In addition, in this embodiment, the synchronous rectification unit 32a includes an upper switching element 37a and a lower switching element 38 that are connected in series. The connection switch 42 includes a connection switch 42-1 (first switch) arranged on the connection line on the low potential side and a connection switch 42-2 (second switch) arranged on the connection line on the high potential side. including.

As a result, the power conditioner 1a according to the present embodiment has the same effect as the first embodiment by the connection switch 42-1 and the connection switch 42-2. can be prevented. Further, the power conditioner 1a according to the present embodiment can safely supply electric power to the control unit 50 and safely operate the power conditioner 1a even when the system relay 24 is welded, for example. .

It should be noted that the present invention is not limited to the above embodiments, and can be modified without departing from the scope of the present invention.
For example, in each of the above embodiments, the power conditioner 1 (1a) has been described as an example of a grid connection device, but the present invention is not limited to this, and may be another grid connection device. good too.

In each of the above-described embodiments, the DC/DC conversion unit 10 is described as an example of an insulated DC/DC conversion unit. may be an insulated DC/DC converter having another configuration.

Further, in each of the above embodiments, the inverter section is not limited to the inverter section 20, and may be an inverter section having another configuration.
Further, in each of the above embodiments, the AC/DC conversion section is not limited to the AC/DC conversion section 30 (30a), and may be an AC/DC conversion section with another configuration. An example will be described in which the conversion control unit 36 of the AC/DC conversion unit 30 (30a) controls switching of each MOSFET of the inverter circuit 33 and each MOSFET of the synchronous rectification unit 35 by the LLC method to generate the voltage V2. However, it is not limited to this, and switching may be controlled by other methods.

Further, in each of the above embodiments, an example of using an N-type MOSFET as a switching element in each section was described, but the present invention is not limited to this, and some or all of the switching elements in each section may be replaced with other switching elements. may be used.

Further, in each of the above-described embodiments, an example in which the inverter control unit 25 controls the connection switches 42 (42-1, 42-2) has been described, but the present invention is not limited to this. You may make it control by other control parts, such as. Also, a dedicated control unit for controlling the connection switches 42 (42-1, 42-2) may be newly provided.

Further, in each of the above embodiments, the conversion control unit 15, the inverter control unit 25, the conversion control unit 36, and the control unit 50 may be realized by circuit means, or a CPU (Central Processing Unit) may execute a program. It may be implemented by software processing that causes the

Also, part or all of the functions of the conversion control unit 15, the inverter control unit 25, the conversion control unit 36, and the control unit 50 described above may be realized as an integrated circuit such as LSI (Large Scale Integration). Each function mentioned above may be processor-ized individually, and may integrate|stack and processor-ize a part or all. Also, the method of circuit integration is not limited to LSI, but may be realized by a dedicated circuit or a general-purpose processor. In addition, when an integration circuit technology that replaces LSI appears due to advances in semiconductor technology, an integrated circuit based on this technology may be used.

Reference Signs List 1, 1a, 100 power conditioner 2 DC power supply 3 commercial power supply 10, 110 DC/DC conversion unit 11 input filter 12, 21, 33 inverter circuit 13, 34 transformer 14, 32, 35 synchronous rectification unit 15, 36 conversion control unit 20, 120 inverter section 22, 31 noise filter 23 isolated relay 24 system relay 25 inverter control section 30, 130 AC/DC conversion section 37, 37-1, 37-2 diode 37a, 37a-1, 37a-2, 38, 38-1, 38-2 Switching element 40, 40a Connection part 41, 41-1, 41-2 Connection diode 42, 42-1, 42-2 Connection switch 50, 150 Control part

Claims (6)

an insulated DC/DC converter that converts DC power supplied from a DC power supply into DC power of a first voltage;
an inverter unit that converts the DC power of the first voltage converted by the DC/DC conversion unit into AC power that can be connected to a grid, and supplies the AC power to an AC load;
an AC/DC converter that rectifies AC power supplied from a system power supply into DC power, and converts the rectified DC power into DC power of a second voltage, which is a power supply for control;
a connection unit that connects a power supply line for the first voltage DC power converted by the DC/DC conversion unit and a power supply line for the rectified DC power rectified by the AC/DC conversion unit. Grid interconnection device. The AC/DC conversion unit includes a synchronous rectification unit that rectifies AC power supplied from the system power supply,
The connection unit is configured to connect the output line of the inverter unit and the power supply line of the system power supply, when the synchronous rectification unit operates, the power supply line of the DC power of the first voltage, The system interconnection device according to claim 1, further comprising a switch that disconnects the rectified DC power from a power supply line. The connecting part is
the switch having a body diode;
and a connection diode disposed so as to be in a forward direction when supplying DC power from the DC power line of the first voltage to the rectified DC power line. A grid connection device as described. The synchronous rectification unit comprises an upper diode and a lower switching element connected in series,
The connection diode includes a first diode arranged on the connection line on the low potential side and a second diode arranged on the connection line on the high potential side,
The system interconnection device according to claim 3, wherein the switch is arranged on the connection line on the low potential side. The synchronous rectification unit comprises an upper switching element and a lower switching element connected in series,
4. The switch according to claim 2, wherein the switch includes a first switch arranged on the connection line on the low potential side and a second switch arranged on the connection line on the high potential side. Grid connection device. an insulated DC/DC converter that converts DC power supplied from a DC power supply into DC power of a first voltage;
an inverter unit that converts the DC power of the first voltage converted by the DC/DC conversion unit into AC power that can be connected to a grid, and supplies the AC power to an AC load;
an AC/DC converter that rectifies AC power supplied from a system power supply into DC power, and converts the rectified DC power into DC power of a second voltage, which is a power supply for control;
a connection unit that connects a power supply line for the first voltage DC power converted by the DC/DC conversion unit and a power supply line for the rectified DC power rectified by the AC/DC conversion unit. power conditioner.

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