JP2015130773A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and light power conversion device.SOLUTION: A power conversion device 1 includes an inverter circuit 12 for converting DC power to AC power. A filter circuit 15 is disposed in a single phase three-wire circuit 1b disposed between the inverter circuit 12 and a system AC end 1a, and smooths the AC power output from the inverter circuit 12. A high frequency transformer 14 is disposed between the inverter circuit 12 and the filter circuit 15, has a single phase three-wire output on the side of the filter circuit 15, and converts power at a switching frequency of the inverter circuit 12. The power conversion device 1 further includes a self-contained output circuit 16 disposed between the filter circuit 15 and the system AC end 1a, and branches from the single phase three-wire circuit 1b. The self-contained output circuit 16 provides a self-contained output AC end 16a. The self-contained output circuit 16 permits a voltage line output (200 V) and a neutral line output (100 V).

Description

  The invention disclosed herein relates to a power conversion device having a single-phase three-wire AC terminal for grid connection and a low-voltage AC terminal for independent output.

  Patent document 1 discloses a power converter having a single-phase three-wire AC terminal and a single-phase two-wire AC terminal. This device uses a transformer having a single-phase three-wire terminal. The transformer of this device is a low-frequency transformer that is directly connected to the AC end and corresponds to the frequency of power at the AC end.

JP-A-5-93746

  In the configuration of the prior art, a low-frequency transformer having a single-phase three-wire terminal is used. However, low-frequency transformers are large and heavy. For this reason, it has the subject that an apparatus enlarges and the weight of an apparatus becomes heavy. In addition, there is a problem that the price of the device becomes high. In view of the above or other aspects not mentioned, there is a need for further improvements in power conversion devices.

  One of the objects of the invention is a small and light weight that has a single-phase three-wire AC terminal for grid connection and a low-voltage AC terminal for independent output, and can extract various voltages at the independent output. It is to provide a power conversion device.

  The invention disclosed herein employs the following technical means to achieve the above object. Note that the reference numerals in parentheses described in the claims and in this section indicate the correspondence with the specific means described in the embodiments described later, and do not limit the technical scope of the invention. .

  A power converter is provided by one of the disclosed inventions. The invention relates to an inverter circuit (12) for converting DC power to AC power in a power converter capable of outputting AC power to a single-phase three-wire AC terminal (1a) connected to the grid (2). A single-phase three-wire circuit (1b) provided between the inverter circuit and the system AC terminal, and a filter circuit (15) provided in the single-phase three-wire circuit for smoothing the AC power output from the inverter circuit 215), a high-frequency transformer (14, 214) provided between the inverter circuit and the filter circuit, having a single-phase three-wire output on the filter circuit side and converting power at the switching frequency of the inverter circuit, and a filter circuit A self-supporting output circuit (16) provided between the power supply and the AC terminal for the system and capable of outputting between the voltage line and the neutral line without going through the system by branching from the single-phase three-wire circuit. Characterized in that it obtain.

  According to this configuration, when the inverter circuit outputs AC power, AC power by a single-phase three-wire system is obtained by the high-frequency transformer. For this reason, compared with the low frequency transformer which converts electric power in low frequency like the frequency of the alternating current power of a system | strain, a small and lightweight power converter device is provided. In addition, an inexpensive power conversion device may be provided. Further, a self-supporting output circuit that branches from the single-phase three-wire circuit is provided. The self-supporting output circuit can supply AC power having a voltage (for example, 200V) generated by the voltage-line output and AC voltage having a voltage (for example, 100V) generated by the neutral-line output. Thereby, AC power having a plurality of voltages can be supplied.

  According to a second aspect of the present invention, the filter circuit (15, 215) includes a capacitive element (15a) provided between the voltage line and the neutral line. According to this configuration, the power switched by the inverter circuit by the capacitive element is smoothed.

  According to a third aspect of the present invention, the filter circuit (15) includes an inductive element (15b) provided on the voltage line. According to this configuration, the electric power is smoothed by the capacitive element and the inductive element.

  The invention described in claim 4 is characterized in that the filter circuit (215) includes the capacitive element (15a) without including the inductive element. According to this configuration, electric power is smoothed by the capacitive element without using an inductive element. At this time, the leakage inductance of the high-frequency transformer functions as a reactor.

  The invention according to claim 5 is characterized in that the leakage inductance of the high-frequency transformer is set so as to provide a part or all of the reactor for smoothing the electric power switched by the inverter circuit. According to this configuration, the inductive element that provides the reactor can be reduced in size or eliminated.

  The invention according to claim 6 is provided between the branch part (17) of the self-supporting output circuit and the system AC terminal (1a) in the single-phase three-wire circuit, and between the branch part and the system AC terminal. A circuit breaker (18) that opens and closes and a control device (21) that interrupts the circuit breaker when the system is out of power and enables output of AC power to a self-supporting output circuit. According to this configuration, it is possible to output power to the self-supporting output circuit without affecting the system when the system is interrupted.

  The invention described in claim 7 further includes a power supply device (11) for supplying DC power to the inverter circuit.

  The invention according to claim 8 is characterized in that the power supply device (11) is a secondary battery charged from the system via an inverter circuit.

It is a block diagram of the power converter device concerning a 1st embodiment of the invention. It is a block diagram of the power converter device which concerns on 2nd Embodiment of invention.

  A plurality of modes for carrying out the invention disclosed herein will be described with reference to the drawings. In each embodiment, portions corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals and redundant description may be omitted. Further, in the following embodiments, the correspondence corresponding to the matters corresponding to the matters described in the preceding embodiments is indicated by adding reference numerals that differ only by one hundred or more, and redundant description may be omitted. . In each embodiment, when only a part of the structure is described, the other parts of the structure can be applied with reference to the description of the other forms.

(First embodiment)
In FIG. 1, the power conversion device 1 is connected to a system 2. The system 2 is a power network that includes a power generation facility and can supply power to a plurality of loads. The system 2 is a large-scale power network also called commercial power. The grid 2 may be a small-to-medium power network constructed on the premises such as a residence or a business office. The system 2 supplies single-phase three-wire power. In this embodiment, the single-phase three wires are supplied by the neutral wire O and the voltage wires U and V. The electric power supplied between the voltage lines U and V is called an output between voltage lines or an output between phases. The electric power supplied between one of the voltage lines U and V and the neutral line O is called an output between neutral lines. In this embodiment, the power line output is 200V. The neutral line output is 100V. The electric power supplied from the system 2 is 50 Hz or 60 Hz. The grid 2 may be interrupted in a planned manner or due to an accident.

  The power conversion device 1 provides a distributed power supply device. In the figure, one power converter 1 is shown. A plurality of power conversion devices 1 can be connected to the system 2. The plurality of power conversion devices 1 can receive power from the grid 2 and supply power to the grid 2. Further, the power conversion device 1 can be separated from the grid 2 and supply power to the load.

  The power conversion device 1 has a single-phase three-wire system AC terminal 1 a connected to the system 2. The power converter 1 can receive AC power from the AC terminal 1a for the system. The power converter 1 can output AC power to the system AC terminal 1a. The power converter 1 has a single-phase three-wire circuit 1b including a system AC terminal 1a.

  The power conversion device 1 has a DC terminal 1 c connected to the power supply device 11. The power supply device 11 is a secondary battery. The secondary battery can be provided by, for example, a lithium ion battery. The power supply device 11 supplies DC power to the DC terminal 1c. The power supply device 11 can include a generator. In this embodiment, the power supply device 11 is charged with electric power supplied from the system 2. Further, the power supply device 11 can supply power to the grid 2. Furthermore, the power supply device 11 can independently supply power to the load.

  The power converter 1 includes an inverter circuit (INV) 12 that converts DC power into AC power. The inverter circuit 12 is provided between the system AC terminal 1a and the DC terminal 1c. The inverter circuit 12 is provided between the single-phase three-wire circuit 1b and the DC terminal 1c. In other words, the single-phase three-wire circuit 1b is provided between the inverter circuit 12 and the system AC terminal 1a. The inverter circuit 12 can be provided by a bridge circuit configured by a plurality of switching elements. The inverter circuit 12 provides AC / DC conversion and orthogonal conversion. The switching element of the inverter circuit 12 is switching-driven at a high frequency of several kHz to several tens kHz. For example, when the inverse circuit 12 performs orthogonal transform, the waveform appearing at the AC terminal 12a is a rectangular waveform that is turned on and off at a high frequency so as to output a predetermined voltage and / or current.

  The power conversion device 1 includes a converter circuit (CNV) 13 that converts the voltage of DC power. The converter circuit 13 is provided between the DC terminal 1 c and the inverter circuit 12. The converter circuit 13 can be provided by a bidirectional DCDC converter circuit. The converter circuit 13 converts the voltage of the DC power supplied to the DC terminal and supplies it to the inverter circuit 12. The converter circuit 13 converts the voltage of the DC power supplied from the inverter circuit 12 and supplies it to the DC terminal 1 c, that is, the power supply device 11.

  The power conversion device 1 includes a high-frequency transformer 14. The high frequency transformer 14 is provided at the AC terminal 12 a of the inverter circuit 12. The high frequency transformer 14 is provided between the inverter circuit 12 and the single-phase three-wire circuit 1b. The high-frequency transformer 14 is an insulating transformer in which the primary side and the secondary side are insulated. The high-frequency transformer 14 has a single-phase two-wire winding and a single-phase three-wire winding. When power is supplied from the system 2 to the power supply device 11, the single-phase three-wire winding provides the primary side, and the single-phase two-wire winding provides the secondary side. When power is supplied from the power supply 11, the single-phase two-wire winding provides the primary side, and the single-phase three-wire winding provides the secondary side. The high-frequency transformer 14 converts the power before smoothing that appears at the AC terminal 12 a of the inverter circuit 12. The high frequency transformer 14 performs power conversion at the switching frequency of the inverter circuit 12.

  The power conversion device 1 includes a filter circuit 15 provided in the single-phase three-wire circuit 1b. The filter circuit 15 is also called a smoothing circuit or a noise suppression circuit. The filter circuit 15 is provided between the high-frequency transformer 14 and the system AC terminal 1a. In other words, the high-frequency transformer 14 is provided between the inverter circuit 12 and the filter circuit 15. The high-frequency transformer 14 has a single-phase three-wire output on the filter circuit 15 side. The filter circuit 15 smoothes the AC power output from the inverter circuit 12. The filter circuit 15 includes a capacitive element 15a provided between the voltage line and the neutral line. The filter circuit 15 includes an inductive element 15b provided on the voltage line. Inductive element 15b provides a reactor for smoothing the AC power supplied from inverter circuit 12. The filter circuit 15 is an LC filter having an interphase capacitor 15a and a normal mode coil 15b provided on the voltage line.

  The power conversion device 1 includes a self-supporting output circuit 16 that can supply AC power to a load without going through the grid 2. The independent output circuit 16 branches off from the single-phase three-wire circuit 1b. The self-supporting output circuit 16 branches off from a branch portion 17 provided between the filter circuit 15 and the system AC terminal 1a. The self-supporting output circuit 16 can output between voltage lines and output between neutral lines. The self-supporting output circuit 16 has a self-supporting output AC terminal 16a to which an external load can be connected. The independent output AC terminal 16a is provided by a single-phase three-wire system. Between the two voltage lines, 200 V which is an output between the voltage lines is obtained. A neutral line output of 100 V is obtained between one of the two voltage lines and the neutral line. The self-sustained output circuit 16 has a self-sustained output AC terminal 16a for a single-phase three-wire system including two voltage lines and one neutral line in order to enable output between voltage lines and output between neutral lines. Is provided.

  The AC terminal 16a for self-sustained output can include a connection terminal, for example, an outlet, for connecting a load that is required to be used when the system 2 has a power failure. As shown in the figure, the independent output AC terminal 16a can be provided by three connection terminals that allow either one of the output between the voltage lines and the output between the neutral lines. The AC terminal 16a for self-supporting output may be connected in parallel to a plurality of sets of connection terminals in order to allow simultaneous output between voltage lines and output between neutral lines. For example, the AC terminal 16a for independent output may have at least one set of connection terminals for output between voltage lines, for example, an outlet, and at least one set of connection terminals for output between neutral lines, for example, an outlet. it can.

  The power converter 1 has the circuit breaker 18 provided in the single-phase three-wire circuit 1b. The circuit breaker 18 is provided between the branch portion 17 for the self-supporting output circuit 16 in the single-phase three-wire circuit 1b and the system AC terminal 1a. In other words, the branch portion 17 is provided between the filter circuit 15 and the circuit breaker 18. This configuration enables a self-supporting power supply that supplies power to the self-supporting output circuit 16 while cutting off the connection with the system 2. The circuit breaker 18 opens and closes two voltage lines and a neutral line. As a result, the circuit breaker 18 opens and closes between the branch portion 17 and the system AC terminal 1a.

  The power conversion device 1 includes a control device (CTL) 21. The control device 21 controls the inverter circuit 12, the converter circuit 13, and the circuit breaker 18. The control device 21 provides power reception control from the system 2 and reverse power flow control to the system 2. The control device 21 causes the power conversion device 1 to function as a power conditioner having a grid connection function. Furthermore, the control device 21 provides self-sustained control for supplying power to the self-sustained output circuit 16 when the system 2 is out of power.

  The control device 21 is an electronic control device. The control device has at least one arithmetic processing unit (CPU) and at least one memory device (MMR) as a storage medium for storing programs and data. The control device is provided by a microcomputer including a computer-readable storage medium. The storage medium stores a computer-readable program non-temporarily. The storage medium can be provided by a semiconductor memory or a magnetic disk. The controller can be provided by a computer or a set of computer resources linked by a data communication device. The program is executed by the control device to cause the control device to function as the device described in this specification and to cause the control device to perform the method described in this specification. The control device provides various elements. At least some of those elements can be referred to as a means for performing functions, and in another aspect, at least some of those elements can be referred to as constituent blocks or modules.

  In the power reception control, the control device 21 controls the inverter circuit 12 and the converter circuit 13 so as to charge the secondary battery that is the power supply device 11 with the power supplied from the system 2. At this time, the secondary battery as the power supply device 11 is charged from the system 2 via the inverter circuit 12. In the reverse power flow control, the control device 21 controls the inverter circuit 12 and the converter circuit 13 so as to supply power to the grid 2 with the power supplied from the power supply device 11.

  In the self-sustained control, the control device 21 controls the inverter circuit 12, the converter circuit 13, and the circuit breaker 18 so as to supply power to the self-sustained output AC terminal 16a with the power supplied from the power supply device 11. The control device 21 opens the circuit breaker 18 when the system 2 is out of power and enables AC power to be output to the self-supporting output circuit 16. In the self-sustained control, when the soundness of the system 2 is confirmed even when the system 2 is in a power failure state, both the reverse power flow to the system 2 and the output to the self-supporting output circuit 16 are enabled. The circuit breaker 18 may be closed. For example, when only a part of the system 2 to which the power conversion device 1 is connected is healthy and is disconnected from other parts of the system 2, a load connected to a part of the system and a self-supporting output circuit Power can be supplied to the load connected to 16. In reverse power flow control and self-sustained control, the power supply device 11 supplies DC power to the inverter circuit 12.

  According to this configuration, in the reverse power flow control and / or the self-sustaining control, the high-frequency transformer 14 can obtain AC power by a single-phase three-wire system. For this reason, compared with the low frequency transformer which carries out power conversion in the low frequency like the frequency of the alternating current power of the system | strain 2, the small and lightweight power converter device 1 is provided. In addition, an inexpensive power conversion device may be provided.

  Further, a self-supporting output circuit 16 that branches from the single-phase three-wire circuit 1b is provided. The self-supporting output circuit 16 can supply AC power having a voltage (200V) generated by the voltage line output and AC voltage having a voltage (100V) generated by the neutral line output. Thereby, AC power having a plurality of voltages can be supplied.

  In the self-sustained control in which the system 2 has a power failure, the connection with the system 2 can be interrupted by the circuit breaker 18. Therefore, a plurality of voltages of AC power can be supplied to the independent output circuit 16 without affecting the system 2.

  In this embodiment, 200 V supplied by a single-phase three-wire system and 100 V supplied by a single-phase two-wire system can be supplied to the independent output AC terminal 16 a of the independent output circuit 16. Therefore, it is possible to supply power to various loads even when the system 2 is out of power. For example, since power can be supplied selectively or simultaneously to a normal load rated at 100 V and a load with a relatively large power consumption rated at 200 V, high convenience can be provided in a house or business establishment.

  Furthermore, in this embodiment, since the insulating high-frequency transformer 14 is used, noise can be blocked in the high-frequency transformer 14. For example, the entry of external noise from the system 2 and / or the independent output circuit 16 is suppressed. Further, noise emission from the inverter circuit 12 and / or the converter circuit 13 to the outside is suppressed.

(Second Embodiment)
This embodiment is a modification based on the preceding embodiment. In the above embodiment, the reactor is provided by the inductive element 15 b of the filter circuit 15. Instead, in this embodiment, a reactor is provided by the leakage inductance of the high-frequency transformer 14.

  As illustrated in FIG. 2, the filter circuit 215 of this embodiment includes only the capacitive element 15a without including the inductive element 15b. In this configuration, the leakage inductance of the high-frequency transformer 214 is set so as to provide all of the reactor for smoothing the electric power switched at a high frequency by the inverter circuit 12. According to this structure, a power converter device can be provided without providing the induction element 15b that provides the reactor. The single-phase three-wire circuit 1b may include an inductive element for noise prevention such as a normal coil or a common mode coil.

(Other embodiments)
The invention disclosed herein is not limited to the embodiments for carrying out the invention, and can be implemented with various modifications. The disclosed invention is not limited to the combinations shown in the embodiments, and can be implemented in various combinations. Embodiments can have additional parts. The portion of the embodiment may be omitted. The parts of the embodiments can be replaced or combined with the parts of the other embodiments. The structure, operation, and effect of the embodiment are merely examples. The technical scope of the disclosed invention is not limited to the description of the embodiments. Some technical scope of the disclosed invention is indicated by the description of the claims, and should be understood to include all modifications within the meaning and scope equivalent to the description of the claims. It is.

  For example, the means and functions provided by the control device can be provided by software only, hardware only, or a combination thereof. For example, the control device may be configured by an analog circuit.

  Further, the leakage inductance of the high frequency transformer may be set so as to provide only a part of the reactor for smoothing the electric power switched by the inverter circuit 12. According to this configuration, the induction element for providing the reactor can be reduced in size and / or weight.

1 power converter,
1a AC terminal for system, 1b Single-phase three-wire circuit, 1c DC terminal,
2 systems,
11 power supply equipment, 12 inverter circuit, 12a AC terminal,
13 Converter circuit,
14, 214 high frequency transformer,
15, 215 filter circuit, 15a capacitive element, 15b inductive element,
16 independent output circuit, 16a AC terminal for independent output,
17 branch part, 18 circuit breaker,
21 Control device.

Claims (8)

In a power converter capable of outputting AC power to a single-phase three-wire system AC terminal (1a) connected to the system (2),
An inverter circuit (12) for converting DC power into AC power;
A single-phase three-wire circuit (1b) provided between the inverter circuit and the system AC terminal;
A filter circuit (15, 215) that is provided in the single-phase three-wire circuit and smoothes the AC power output from the inverter circuit;
A high-frequency transformer (14, 214) provided between the inverter circuit and the filter circuit, having a single-phase three-wire output on the filter circuit side and performing power conversion at a switching frequency of the inverter circuit;
A self-supporting output circuit which is provided between the filter circuit and the AC terminal for the system, and can branch out from the single-phase three-wire circuit and output between the voltage lines and between the neutral lines without going through the system (16). A power conversion device comprising:   The power converter according to claim 1, wherein the filter circuit (15, 215) includes a capacitive element (15a) provided between a voltage line and a neutral line.   The said filter circuit (15) is provided with the induction | guidance | derivation element (15b) provided in the said voltage line, The power converter device of Claim 2 characterized by the above-mentioned.   The power converter according to claim 3, wherein the filter circuit (215) includes the capacitive element (15a) without including the inductive element.   5. The leakage inductance of the high-frequency transformer is set so as to provide a part or all of a reactor for smoothing the electric power switched by the inverter circuit. The power conversion apparatus of crab. Circuit breaker provided between the branch part (17) of the self-sustained output circuit and the system AC terminal (1a) in the single-phase three-wire circuit, and opens and closes between the branch part and the system AC terminal. (18)
6. The control device according to claim 1, further comprising: a controller (21) that interrupts the circuit breaker when the system is out of power and enables AC power to be output to the self-supporting output circuit. The power conversion apparatus of crab.   The power converter according to any one of claims 1 to 6, further comprising a power supply device (11) for supplying DC power to the inverter circuit.   The power converter according to claim 7, wherein the power supply device (11) is a secondary battery charged from the system via the inverter circuit.

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