JP6136684B2 - Power supply system, power supply method, and load conversion device - Google Patents

Description

  The present invention relates to a power supply system, a power supply method, and a load converter, and more particularly to a technique for controlling a current waveform of a line.

  Conventionally, an electric power system including a power conditioner that converts direct current supplied from a solar battery or a storage battery into alternating current and outputs the alternating current to a load has been proposed (see Patent Document 1). Specifically, a DC / DC converter is inserted between the solar battery and the DC bus line, and a bidirectional DC / DC converter is inserted between the storage battery and the DC bus line. An inverter circuit is interposed between the DC bus line and the load, and direct current supplied from the DC bus line is converted into alternating current by the inverter circuit and supplied to the load.

JP2012-161189A

  However, in the technique described in Patent Document 1, the ripple component of the current flowing through the DC bus line may increase.

  Therefore, an object of the present invention is to provide a power supply system, a load conversion device, and a power supply method capable of reducing a ripple component of a current flowing through a line.

  The power supply system according to the present invention includes a power source that supplies direct current to a line composed of a trunk line and a branch line connected to the trunk line, and a direct current that is provided for each of a plurality of load devices and is supplied from the trunk line through the branch line. A power supply system comprising a plurality of load conversion devices having inverter circuits that convert to alternating current and supply to the load device, wherein the plurality of load conversion devices supply alternating current to each corresponding load device. The phases are shifted from each other.

Further, the power supply method according to the present invention from another viewpoint is provided for each of a plurality of load devices, a power source for supplying a direct current to a line composed of a main line and a branch line connected to the main line, Power supply method using a power supply system comprising: N (N is an integer of 2 or more) load converters having an inverter circuit that converts a direct current supplied from a branch line through a branch line into an alternating current and supplies the alternating current to a load device In this case, there are N load conversion devices, and a phase shift amount of an AC input to another load device with respect to an AC input to one of the load devices is φ. Then, there is a step of setting the phase of the alternating current input to each of the plurality of load devices so that the relational expression shown in the following expression (1) is satisfied.

  Further, the power supply method according to the present invention from another viewpoint is provided for each of a plurality of load devices, a power source for supplying a direct current to a line composed of a main line and a branch line connected to the main line, A power supply method using a power supply system comprising: a plurality of load conversion devices having inverter circuits that convert direct current supplied from a branch line into alternating current and supply the load device to a load device, wherein the plurality of load conversion devices When each device determines that a load conversion device other than its own device is operating based on the fluctuation range of the voltage of the line, the method includes a step of setting an AC phase based on the voltage of the line.

  The present invention can be realized not only as such a characteristic power supply system and power supply method, but also as a program for causing a computer to execute the characteristic steps performed in such a power supply method. Can be. Moreover, it is realizable as a semiconductor integrated circuit which implement | achieves a part or all of the said electric power supply system. Furthermore, the program can be stored in a recording medium such as a CD-ROM.

  According to the present invention, it is possible to reduce the ripple component of the current flowing through the line.

1 is a diagram illustrating a configuration of a power supply system according to a first embodiment. 1 is a diagram illustrating a configuration of a load conversion device according to a first embodiment. FIG. 6 is a sequence diagram illustrating a parent device selection operation in the power supply system according to the first embodiment. 3 is a flowchart illustrating an operation of a command unit according to the first embodiment. It is a figure which shows the simulation result of the input current to the converter for loads in the electric power supply system which concerns on Embodiment 1. FIG. It is a figure which shows the simulation result which shows the electric current which flows through the trunk line of the track | line in the electric power supply system which concerns on Embodiment 1. FIG. It is a figure which shows the structure of the electric power supply system 301 which concerns on Embodiment 2. FIG. It is a figure which shows the structure of load converter 207A (207B) which concerns on Embodiment 2. FIG. 10 is a flowchart illustrating an operation of a control unit according to the second embodiment. 6 is an equivalent circuit showing a power supply system according to a second embodiment. It is a simulation result which shows the line voltage in the electric power supply system which concerns on Embodiment 2, the input current to the converter for loads, and the electric current output from the converter for loads. It is a simulation result which shows the line voltage in the electric power supply system which concerns on Embodiment 2, the input current to the converter for loads, and the electric current output from the converter for loads. It is a simulation result which shows the input current to each of two load converters in the electric power supply system which concerns on Embodiment 2. FIG. It is a simulation result which shows the electric current which flows through the trunk line of the track | line in the electric power supply system which concerns on Embodiment 2. FIG. It is the simulation result which shows the line voltage in the electric power supply system which concerns on Embodiment 2. FIG.

[1. Summary of Embodiment]
In general homes and offices, the power supplied to various electrical devices is usually AC from the power system.

  On the other hand, for example, to use natural energy and to cope with power outages in power systems, power generators such as solar cells and storage batteries are installed, and direct current from these power generators and storage batteries is converted to alternating current. Thus, a DC power distribution system for supplying various electric devices has been developed. An example of this type of DC power distribution system is described in Patent Document 1.

  However, when an alternating current is to be supplied from a DC bus line to a plurality of electrical devices using the technique described in Patent Document 1, normally, a plurality of inverter circuits are connected to the DC bus line, and each inverter circuit is connected. It is considered that AC is supplied to the electrical equipment from Here, the DC bus line is usually composed of a main line connected to a power generation device or a storage battery via a DC / DC converter, and a branch line connecting the main line and each inverter circuit.

  However, according to this configuration, when the phase of the AC supplied from each of the plurality of inverter circuits to the same phase is the same, when the DC input to each inverter circuit through the branch line is added, the ripple component of each DC Are in a mutually reinforcing relationship. In this case, the DC ripple component flowing through the main line increases, and the direct current flowing through the main line increases. Then, in order to smooth the direct current flowing through the main line, it is necessary to connect a capacitor having a large capacitance to the main line, which may increase the size and cost of the direct current distribution system.

  In addition, if the AC power supply is connected to the main line of the DC power distribution system via an AC / DC converter to connect the system, a switch for protecting the DC power distribution system is connected between the main line and the AC power supply. Configuration is conceivable. In this case, if the DC ripple component flowing through the trunk line increases, the rated current or rated voltage required for the switch must be increased, which may increase the cost required for the switch.

The embodiments of the present invention have been made in view of the above reasons, and the gist includes at least the configurations shown in (1) to (8) below.
(1) A power supply system according to an embodiment of the present invention from a certain viewpoint is provided for each of a plurality of load devices and a power source that supplies a direct current to a line composed of a main line and a branch line connected to the main line. A plurality of load converters having an inverter circuit that converts a direct current supplied from a main line through a branch line into an alternating current and supplies the converted load to a load device, each of the plurality of load converters The phases of the alternating current supplied to the corresponding load devices are shifted from each other.

  According to this configuration, the phases of the alternating current supplied from the plurality of load conversion devices to the corresponding load devices are shifted from each other. Accordingly, the phases of the DC ripple components input from the main line to the inverter circuit included in each of the plurality of load converters through the branch lines are also shifted from each other. Thereby, when the direct current flowing through the branch line is added, at least a part of the direct current ripple component flowing through one branch line is canceled by the direct current ripple component flowing through the other branch line. Since the direct current flowing through the main line corresponds to the addition of the direct current flowing through the branch line, in this configuration, the ripple component of the direct current flowing through the main line is reduced.

(2) Further, in the power supply system according to the embodiment of the present invention, there are N load conversion devices, and other load devices for an alternating current input to one of the load devices. If the amount of phase shift of the input alternating current is φ, the relational expression shown in the following equation (1) may be established for φ.
According to this configuration, the relational expression shown in the above equation (1) is established for the shift amount of the phase of the alternating current input to another load device with respect to the alternating current input to one of the plurality of load devices. To do. In this case, the relational expression shown in Expression (1) is also established for the phase shift amount of the DC ripple component input to the inverter circuit included in each of the plurality of load converters from the main line through the branch line. Thereby, when the direct currents flowing through the branch lines are added, the direct current ripple components flowing through the respective branch lines are substantially canceled by the direct current ripple components flowing through the other branch lines. Therefore, it is possible to substantially eliminate the DC ripple component flowing through the main line.

(3) Further, in the power supply system according to the embodiment of the present invention, the plurality of load conversion devices are such that the load conversion device to which power is first turned on operates as a parent device, and the other load conversion devices. The load converter that operates as a slave unit and operates as the master unit may set the amount of phase shift.
According to this configuration, only one of the plurality of load conversion devices that operates as the parent device performs the process of setting the phase shift amount. Accordingly, it is possible to reduce the processing load in the entire power supply system as compared with the configuration in which the processing for setting the phase shift amount is performed in each of the plurality of load conversion devices.

(4) Further, in the power supply system according to the embodiment of the present invention, each of the plurality of load conversion devices operates such that other load conversion devices other than the self device operate based on the fluctuation range of the voltage of the line. If it is determined that the AC phase is determined, the AC phase may be set based on the voltage of the line.
According to this configuration, each of the plurality of load conversion devices sets the AC phase based on the voltage of the line. In other words, each load conversion device sets the phase of the alternating current output from the own device without obtaining information on the amount of phase shift of the alternating current output from the other load conversion device from the other load conversion device. . This eliminates the need for each of the plurality of load conversion devices to have a function of communicating with other load conversion devices. Therefore, the configuration of the load conversion device can be simplified.

(5) Further, in the power supply system according to the embodiment of the present invention, each of the plurality of load conversion devices has a peak position of voltage fluctuation of the voltage of the line and an AC peak supplied to the load device by the own device. The AC phase may be set so that the position matches.
According to this configuration, each of the plurality of load converters sets the AC phase so that the peak position of the voltage fluctuation of the line voltage coincides with the peak position of the AC supplied from the own apparatus to the load apparatus. . Thereby, when the direct current flowing through each branch line is added, substantially all of the direct current ripple component flowing through each branch line is canceled by the direct current ripple component flowing through the other branch lines. Therefore, it is possible to substantially eliminate the DC ripple component flowing through the main line.

(6) Further, in the power supply system according to the embodiment of the present invention, the power supply converts the direct current supplied from the power generation device and supplies the converted power to the line, and the alternating current supplied from the alternating current power supply. You may provide at least 1 among the converter for alternating current power supplies which converts into direct current and supplies it to a track | line, and the converter for storage batteries which converts the direct current supplied from a storage battery, and supplies it to a track | line.
According to this configuration, it is possible to reduce the DC ripple component flowing in the main line in the power supply system using the power generation device, the AC power supply, and the storage battery.

(7) Moreover, the electric power supply method which concerns on embodiment of this invention seen from another viewpoint, the power supply which supplies a direct current to the track | line comprised from a trunk line and the branch line connected to the said trunk line, and several load apparatus N (N is an integer greater than or equal to 2) load converters each having an inverter circuit that is provided every time and that converts a direct current supplied from a trunk line through a branch line into an alternating current and supplies the alternating current to a load device. There are N load conversion devices, and the phase of the alternating current input to another load device with respect to the alternating current input to one of the plurality of load devices is present. When the shift amount is φ, the method includes the step of setting the phase of alternating current input to each of the plurality of load devices so that the relational expression shown in the following expression (1) is satisfied.

According to this configuration, the relational expression shown in the above equation (1) is established for the shift amount of the phase of the alternating current input to another load device with respect to the alternating current input to one of the plurality of load devices. To do. Therefore, the relational expression shown in Expression (1) also holds for the phase shift amount of the DC ripple component input from the main line to the inverter circuit included in each of the plurality of load converters through the branch line. As a result, when the direct currents flowing through the branch lines are added, almost all of the direct current ripple components flowing through the branch lines are canceled out by the direct current ripple components flowing through the other branch lines. Therefore, it is possible to substantially eliminate the DC ripple component flowing through the main line.

(8) Moreover, the electric power supply method which concerns on embodiment of this invention seen from the other viewpoint is the power supply which supplies a direct current to the track | line comprised from a trunk line and the branch line connected to the said trunk line, and several load apparatus A power supply method using a power supply system provided with a plurality of load conversion devices each having an inverter circuit that is provided for each and converts a direct current supplied from a trunk line through a branch line into an alternating current and supplies the alternating current to a load device. When each of the plurality of load conversion devices determines that another load conversion device other than its own device is operating based on the fluctuation range of the line voltage, the AC phase is calculated based on the line voltage. Including setting.
According to this configuration, each of the plurality of load conversion devices sets the AC phase based on the voltage of the line. That is, each load converter sets the phase of the alternating current output from its own device without obtaining information regarding the phase of the alternating current output from the other load converter from the other load converter. Thereby, it is not necessary for the load conversion device to have a function of performing communication with other load conversion devices. Therefore, the configuration of the load conversion device can be simplified.

(9) A load converter according to an embodiment of the present invention viewed from another viewpoint is a load converter having an inverter circuit that converts a direct current supplied from a line into an alternating current and supplies the alternating current to the load device. Therefore, the AC phase is set based on the voltage of the line.
According to this configuration, the load converter sets the AC phase based on the voltage of the line. In other words, the load conversion device relates to the phase of the alternating current output by the load conversion device from the other load conversion device when another load conversion device is connected to the line to which the own device is connected. Without obtaining information, set the phase of the alternating current output by the device itself. Thereby, it is not necessary for the load conversion device to have a function of performing communication with other load conversion devices. Therefore, the configuration of the load conversion device can be simplified.

[2. Details of Embodiment]
<Embodiment 1>
<1> Configuration FIG. 1 is a diagram illustrating a configuration of a power supply system 201 according to the present embodiment.
The power supply system 201 includes a storage battery conversion device 101, a power generation device 102, a power generation device conversion device 103, an AC power supply 104, an AC power supply conversion device 105, and a storage battery 106. The power supply system 201 further includes three load conversion devices 107A, 107B, and 107C and a capacitor 109.

  Here, the storage battery conversion device 101, the power generation device conversion device 103, the AC power supply conversion device 105, and the three load conversion devices 107 </ b> A, 107 </ b> B, 107 </ b> C are electrically connected to the line 151. Further, the line 151 includes a main line 151a that connects the storage battery conversion device 101, the power generation device conversion device 103, and the AC power supply conversion device 105, the three load conversion devices 107A, 107B, and 107C, and the main line 151a. It is comprised from the branch line 151b which connects.

  The power supply system 201 is a distributed power supply system such as a solar power supply system, and supplies power to the three load devices 108A, 108B, and 108C through the line 151. Note that the power supply system 201 may perform grid connection.

  In the power supply system 201, direct current supplied from the power generation device 102 and the storage battery 106 is converted into alternating current by each of the three load conversion devices 107A, 107B, and 107C and supplied to the three load devices 108A, 108B, and 108C. .

  The power generation device 102 is a power generation device using natural energy, for example, a solar power generation device or a wind power generator, and outputs generated direct current to the power generation device conversion device 103. The output power of the power generator 102 is, for example, 2.4 kW.

  The power generator conversion device 103 is, for example, a DC / DC converter, converts the direct current received from the power generator 102 into a direct current having a different voltage value, and outputs the direct current to the trunk 151 a of the line 151. The power generation device conversion device 103 maximizes the output power of the power generation device 102 by performing MPPT (maximum power point tracking) control.

  The storage battery 106 is, for example, a lead battery, a lithium ion battery, a nickel-cadmium battery, a nickel-hydrogen battery, a redox flow battery, or a NAS battery. The storage battery 106 has, for example, an electromotive force of 12 V, a capacity of 105 Ah, an output power of 5 kWh, and a 4-series lead storage battery. Alternatively, the storage battery 106 is, for example, a two-series Li-ion battery having an electromotive force of 30 V, a capacity of 40 Ah, and an output power of 2.4 kWh.

  The storage battery conversion device 101 is a bidirectional DC / DC converter that converts a direct current from the storage battery 106 into a direct current having a different voltage value in a discharging operation and outputs the direct current to the main line 151a of the line 151, and in a charging operation, the main line 151a. Is converted into a DC having a different voltage value and output to the storage battery 106.

  The AC power supply conversion device 105 is an AC / DC converter including a power factor correction circuit and the like, converts 100V AC received from the AC power supply 104 in a commercial power system or the like into DC and outputs it to the main line 151a of the line 151. . This AC power converter 105 performs constant current control for controlling the current supplied to the main line 151a to a constant value.

  The three load conversion devices 107A, 107B, and 107C are DC / AC converters that convert the direct current supplied from the trunk line 151a of the line 151 through the branch line 151b into alternating current and output the alternating current to the load devices 108A, 108B, and 108C. Here, the load devices 108A, 108B, and 108C are, for example, home appliances.

  The three load conversion devices 107A, 107B, and 107C are connected to each other via a network 152 so as to communicate with each other. The network 152 may be wired or wireless. One of the three load conversion devices 107A, 107B, and 107C operates as a parent device, and the other two operate as child devices. Then, the load conversion device that operates as the parent device transmits a command value related to the output phase shift amount of the alternating current to another load conversion device that operates as the child device.

  The capacitor 109 is for smoothing the voltage of the main line 151a of the line 151, and is connected to the main line 151a.

FIG. 2 is a diagram showing a configuration of the load conversion device 107A (107B, 107C) according to the present embodiment.
The load conversion device 107A (107B, 107C) includes a control unit 12, a power conversion unit 13, and a command unit 110.

The command unit 110 includes a computer. Each function of the command unit 110 is realized by a computer executing a predetermined computer program. Here, the computer includes a CPU (Central Processing Unit), a memory, an I / O interface, and a bus that connects these components to each other. Note that the control unit 12 is not necessarily limited to one configured from one computer, and may be configured from a plurality of computers.
Command unit 110 transmits a command value related to the amount of phase shift of the alternating current output from the other load conversion device to another load conversion device other than the load conversion device in which the device itself is built. .

  Similar to the command unit 110, the control unit 12 includes a computer. Each function of the control unit 12 is realized by a computer executing a predetermined computer program. Note that the control unit 12 is not necessarily limited to one configured from one computer, and may be configured from a plurality of computers.

The control unit 12 controls the gate drive circuit 23 based on a command value related to the phase shift amount input from the command conversion unit 110 built in the load conversion device or the other load conversion device in which the own device is built. Input the signal.
Further, the control unit 12 stores identification information for identifying each of the load converters 107A, 107B, and 107C belonging to the power supply system 201 in the memory. Then, the control unit 12 refers to the identification information stored in the memory after turning on the power of the load conversion device in which the self-device is built, during the first period (for example, for 10 min). It can be determined whether or not the identification information is transmitted from another load converter.
In addition, when the load conversion device in which the own device is incorporated operates as a parent device, the control unit 12 starts the operation of the command unit 110, and the load conversion device in which the own device is incorporated operates as a child device. In this case, the command unit 110 is not operated.

  The power conversion unit 13 performs an operation of converting the direct current supplied from the line 151 into alternating current and supplying the alternating current to the load device 108A.

The power conversion unit 13 includes a gate drive circuit 23 and an inverter circuit 24.
Inverter circuit 24 includes four transistors 31, 32, 33 and 34, coils 35 and 36, and capacitor 37. The inverter circuit 24 may be configured to include other types of switching elements instead of the transistors.
The gate drive circuit 23 generates gate signals for the transistors 31, 32, 33, 34 in the inverter circuit 24 according to the control signal input from the control unit 12, and outputs the gate signals to the transistors 31, 32, 33, 34.

  The transistors 31, 32, 33, and 34 are, for example, IGBTs (Insulated Gate Bipolar Transistors) having a backflow prevention diode, and perform a switching operation based on a gate signal received from the gate drive circuit 23. Thereby, the direct current supplied from the line 151 is converted into alternating current and supplied to the load device 108A (108B, 108C).

<2> Operation <2-1> Master / Slave Unit Determination Operation First, regarding the power supply system 201 according to the present embodiment, an operation for determining a master unit from among the three load conversion devices 107A, 107B, 107C. explain.
In the power supply system 201, among the three load conversion devices 107A, 107B, and 107C, the load conversion device that is first turned on operates as a parent device, and the other two load conversion devices serve as child devices. Operate. Thereafter, each time the load power supply device selected as the parent device is turned off, the load conversion device selected as the parent device is replaced.

FIG. 3 is a sequence diagram showing a parent device selection operation in the power supply system according to the present embodiment. Here, description will be made assuming that the load conversion device 107A is first turned on.
First, when power is turned on (step S1), the load conversion device 107A checks whether or not identification information is transmitted from the other load conversion devices 107B and 107C (step S2). Specifically, the control unit 12 of the load conversion device 107A has a timer function, and determines whether or not identification information is transmitted from the load conversion devices 107B and 107C during the first period. To do.

Next, it is assumed that the load conversion device 107A determines that there is no transmission of identification information from the other load conversion devices 107B and 107C (step S3). Specifically, this is a case where the load conversion device 107A has not received the identification information from the other load conversion devices 107B and 107C even after the first period has elapsed.
In this case, the load conversion device 107A starts to operate as a parent device (step S4). Specifically, the load conversion device 107A starts transmitting its own identification information to the other load conversion devices 107B and 107C, and operates the command unit 110. Thereafter, the load conversion device 107A repeats transmission of the identification information of the own device to the other load conversion devices 107B and 107C every second period (for example, 5 minutes) shorter than the first period.
Also, the load conversion device 107A operates the command unit 110 to start generation and transmission of command values related to phase shift amounts to the load conversion devices 107B and 107C described later. This “generation of a command value related to the amount of phase shift” will be described in detail in <2-2>.

  On the other hand, when power is turned on for load converter 107B (107C) (step S5 (S11)), whether or not identification information is transmitted from other load converters 107A and 107C (107A and 107B). Is confirmed (step S6 (S12)).

  Here, the load conversion device 107A is turned on before the load conversion devices 107B and 107C, and transmits identification information to the load conversion devices 107B and 107C (step S7 (S13)). Therefore, the load conversion device 107B (107C) determines that the identification information of the load conversion device 107A, which is another device, is transmitted (step S8 (S14)). Then, the load conversion device 107B (107C) transmits the identification information of the own device to the load conversion device 107A (step S9 (S15)).

  Thereafter, the load conversion device 107B (107C) starts operation as a slave (step S10 (S16)).

Next, a case will be described in which only the load conversion device 107A, which is the parent device, is powered off and the other load conversion devices 107B and 107C continue to operate.
In this case, when receiving the power-off instruction, the load conversion device 107A notifies the instruction signal instructing any one of the two load conversion devices 107B and 107C that continue to operate to operate as the master unit. Then, power off operation is performed. Of the load converters 107B and 107C, the one that receives the instruction signal starts the operation of the command unit 110.

  As described above, in the power supply system 201 according to the present embodiment, only one of the three load conversion devices 107A, 107B, and 107C that operates as a master unit (for example, the load conversion device 107A) has a phase. A process of setting the amount of deviation is performed. Therefore, for example, in each of the three load converters, the processing load in the entire power supply system 201 can be reduced as compared with the configuration in which the process of setting the phase shift amount is performed.

<2-2> Operation of Command Unit Next, the operation of the command unit 110 according to the present embodiment will be described.
FIG. 4 is a flowchart showing the operation of the command unit 110 according to this embodiment. Here, description will be made assuming that load conversion device 107A is selected as the parent device.
When the load conversion device 107A is turned on (step S21), the command unit 110 detects the number of load conversion devices included in the power supply system 201 (step S22). Here, the number is detected by counting the types of identification information (see FIG. 3) transmitted from the load converters 107B and 107C.

Next, the command unit 110 determines whether or not the number of load conversion devices included in the power supply system 201 is two or more (step S23).
If it is determined in step S23 that the number of load conversion devices is one (step S23: No), the command unit 110 performs the process of step S27 described later.

On the other hand, when it is determined in step S23 that the number of load converters is two or more (step S23: Yes), the command unit 110 generates a command value related to the phase shift amount (step S24). . Specifically, the command unit 110 uses the following formula (1) for the phase shift amount φ of the AC input to each load device corresponding to another load conversion device based on the number of load conversion devices. The command value is generated so that the following relational expression is satisfied.
Here, N indicates the total number of load conversion devices, and k indicates the order of the load conversion devices. The “order of load conversion devices” is an order arbitrarily given to a plurality of load conversion devices according to the total number thereof. For example, when there are three load converters 107A, 107B, and 107C, “0” is assigned to the load converter 107A in which the own apparatus is incorporated, “1” is assigned to the load converter 107B, and the load converter is installed. 107C is assigned “2”.

  In this case, the phase shift amount of the DC ripple component input to the inverter circuit 24 included in each of the three load converters 107A, 107B, and 107C through the main line 151a through the branch line 151b is also expressed by the relational expression shown in Expression (1). Is established. As a result, when the direct currents flowing through the branch lines 151b are added, almost all of the direct current ripple components flowing through the branch lines are canceled out by the direct current ripple components flowing through the other branch lines. As a result, the DC ripple component flowing through the trunk line 151a is substantially eliminated.

  Thereafter, command unit 110 transmits the generated command value φ to load converters 107B and 107C (step S25). At this time, command unit 110 sets a transmission destination based on the identification information received from load converters 107B and 107C.

  Next, the command unit 110 again detects the number of load conversion devices included in the power supply system 201 (step S26). Here, for example, the command unit 110 performs the process of step S26 after a predetermined period has elapsed after transmitting the command value.

  Subsequently, the command unit 110 determines whether or not the number of load conversion devices that are powered on has been changed (step S27). For example, when the load conversion device 107B is turned off among the three load conversion devices 107A, 107B, and 107C, the command unit 110 determines that the number of load conversion devices that are powered on has been changed.

If it is determined in step S27 that the number of load conversion devices that are powered on has not been changed (step S27: No), the command unit 110 performs the process of step S26 again.
On the other hand, when it is determined in step S27 that the number of load conversion devices that have been powered on has been changed (step S27: YES), command unit 110 determines whether or not load conversion device 107A has received a power-off instruction. Is determined (step S28).

If it is determined in step S28 that load conversion device 107A has received a power-off instruction (step S28: YES), command unit 110 selects one of load conversion devices 107B and 107C, and the master unit Is transmitted (step S29), and the process is terminated.
On the other hand, when it is determined in step S28 that load conversion device 107A has not received a power-off instruction (step S28: NO), command unit 110 performs the process of step S23 again.

<2-3> Simulation Results Next, simulation results of input currents Iinv1, Iinv2, and Iinv3 to the load converters 107A, 107B, and 107C in the power supply system 201 according to the present embodiment will be described.
FIG. 5 is a diagram illustrating simulation results of input currents Iinv1, Iinv2, and Iinv3 to the load converters 107A, 107B, and 107C in the power supply system 201 according to the present embodiment. Here, a case where the command unit 110 shifts the phase of the alternating current output from the three load conversion devices 107A, 107B, and 107C in accordance with the relational expression (1) is shown. That is, in the formula (1), N is 3 and k is 0, 1, and 2.
As shown in FIG. 5, the phases of the currents Iinv1, Iinv2, and Iinv3 input to the three load converters 107A, 107B, and 107C are shifted by π / 3.

FIG. 6 shows a simulation result indicating a current flowing through the trunk line 151a of the line 151 in the power supply system 201 according to the present embodiment. Here, the trunk line 151a of the line 151 in the configuration in which the phases of the input currents Iinv1, Iinv2, Iinv3 to the three load converters 107A, 107B, 107C are the same phase (hereinafter referred to as “Comparative Example 1”). The flowing current is also shown.
The current flowing through the main line 151a of the line 151 corresponds to the sum of the input currents Iinv1, Iinv2, Iinv3 to the three load converters 107A, 107B, 107C. As shown in FIG. 6, in the first comparative example, the phases of the currents Iinv1, Iinv2, and Iinv3 flowing into the three load converters 107A, 107B, and 107C are the same, so that the ripple component of the current flowing through the trunk line 151a is It is increasing.

  In contrast, in the power supply system 201 according to the present embodiment, the phases of the input currents Iinv1, Iinv2, and Iinv3 to the three load converters 107A, 107B, and 107C are shifted by π / 3. Thereby, the ripple components of the input currents Iinv1, Iinv2, and Iinv3 are canceled, and the ripple components of the current flowing through the trunk line 151a are reduced. That is, the ripple component of the direct current flowing through the trunk line 151a is reduced by intentionally shifting the phases of the input currents Iinv1, Iinv2, and Iinv3 to the load converters 107A, 107B, and 107C.

<3> Summary Eventually, the power supply system 201 according to the present embodiment has the AC phases supplied from the three load converters 107A, 107B, and 107C to the corresponding load devices 108A, 108B, and 108C, respectively. It is off. Therefore, the phases of the DC ripple components input to the inverter circuit 24 included in each of the three load converters 107A, 107B, and 107C from the main line 151a through the branch line 151b are also shifted from each other. Thereby, when the direct current flowing through the branch line 151b is added, at least a part of the direct current ripple component flowing through the one branch line 151b is canceled by the direct current ripple component flowing through the other branch line 151b. Since the direct current flowing through the trunk line 151a corresponds to the addition of the direct current flowing through the branch line 151b, the power supply system 201 according to the present embodiment reduces the ripple component of the direct current flowing through the trunk line 151a.

As a result of reducing the direct current ripple component flowing through the main line 151a, the capacitance of the capacitor 109 that smoothes the direct current flowing through the main line 151a can be reduced, thereby reducing the size and cost of the power supply system 201. Can be planned.
For example, assume that a switch (not shown) for protecting the power supply system 201 is connected between the main line 151a and the AC power supply 104. In this case, since the rated current or the rated voltage required for the switch can be reduced by reducing the DC ripple component flowing through the trunk line 151a, the cost required for the switch can be reduced.

  Further, in the power supply system 201, the relational expression shown in Expression (1) is established for the phase shift amount φ of the alternating current input to the other load devices 108B and 108C with respect to the alternating current input to the load device 108A. In this case, the phase shift amount of the DC ripple component input to the inverter circuit 24 included in each of the three load converters 107A, 107B, and 107C through the main line 151a through the branch line 151b is also expressed by the relational expression shown in Expression (1). Is established. As a result, when the direct currents flowing through the branch lines 151b are added, almost all of the direct current ripple components flowing through the branch lines are canceled out by the direct current ripple components flowing through the other branch lines. As a result, the DC ripple component flowing through the trunk line 151a is substantially eliminated.

<Embodiment 2>
FIG. 7 is a diagram illustrating a configuration of the power supply system 301 according to the present embodiment.
The power supply system 301 includes a storage battery conversion device 101, a power generation device 102, a power generation device conversion device 103, an AC power supply 104, an AC power supply conversion device 105, and a storage battery 106. The power supply system 201 further includes two load conversion devices 207 </ b> A and 207 </ b> B and a capacitor 109. Here, the storage battery conversion device 101, the power generation device conversion device 103, the AC power supply conversion device 105, and the two load conversion devices 207 </ b> A and 207 </ b> B are electrically connected to the line 151. Further, the line 151 connects the main line 151a that connects the storage battery conversion device 101, the power generation device conversion device 103, and the AC power supply conversion device 105 to each other, the two load conversion devices 207A and 207B, and the main line 151a. Branch line 151b. In addition, about the structure similar to Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted suitably.

FIG. 8 is a diagram illustrating a configuration of the load conversion device 207A (207B) according to the present embodiment.
The load conversion device 207A (207B) includes a control unit 212, a power conversion unit 13, voltage measuring devices 41 and 44, and current measuring devices 42 and 43. In addition, about the structure similar to Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted suitably.

  The voltage measuring instrument 41 measures the voltage of the line 151 (hereinafter referred to as “line voltage”) Vdc and outputs the measured value to the control unit 212. The voltage measuring instrument 44 measures the voltage Vout applied to the load device 108A (108B) and outputs the measured value to the control unit 212. The current measuring instrument 42 measures the current Iinv1 (Iinv2) input from the line 151 to the load converter 207A (207B), and outputs the measured value to the control unit 212. The current measuring instrument 43 measures the current Iout1 (Iout2) output from the load conversion device 207A (207B) to the load device 108A (108B), and outputs the measured value to the control unit 212.

Next, the operation of the control unit 212 according to this embodiment will be described.
FIG. 9 is a flowchart showing the operation of the control unit 212 according to the present embodiment.
When the load conversion device 207A (207B) is powered on (step S31), the control unit 212 detects the fluctuation range ΔVdc of the line voltage Vdc (step S32). Here, the control unit 212 detects the fluctuation range ΔVdc by monitoring the voltage value input from the voltage measuring device 41 only for a predetermined period. Here, the fluctuation range ΔVdc corresponds to, for example, a differential pressure between the maximum value and the minimum value of the line voltage Vdc within a predetermined period (for example, 30 ms).

  Next, the control unit 212 determines whether or not the fluctuation range ΔVdc of the line voltage Vdc exceeds a predetermined threshold voltage ΔVth (step S33). Here, if the fluctuation range ΔVdc exceeds the threshold voltage ΔVth, the control unit 212 determines that the load conversion device other than the load conversion device (for example, the load conversion device 207B) in which the control unit 212 is built (for example, the load conversion device 207B). It is determined that the load conversion device 207A) is already operating. On the other hand, if the fluctuation range ΔVdc is less than the threshold voltage ΔVth, the control unit 212 determines that the other load conversion device (load conversion device 207A) is not operating. That is, the control unit 212 determines whether or not a load conversion device other than the load conversion device in which the device is built is operating based on the fluctuation range ΔVdc of the line voltage Vdc. Further, the threshold voltage ΔVth is set to 2.5 V, for example.

  If it is determined in step S33 that the fluctuation range ΔVdc of the line voltage Vdc is equal to or less than the threshold voltage ΔVth (step S33: No), the control unit 212 operates the power conversion unit 13 as it is (step S36).

  On the other hand, when it is determined in step S33 that the fluctuation range ΔVdc of the line voltage Vdc exceeds the threshold voltage ΔVth (step S33: Yes), the control unit 212 is generated by operating the power conversion unit 13. The phase of the current Iout1 (Iout2) is set (step S34). For example, it is assumed that the load conversion device 207A is operating and the load conversion device 207B is operated later. In this case, the control unit 212 built in the load conversion device 207B is output from the load conversion device 207B to the position of the peak of the line voltage Vdc based on the measurement value acquired from the voltage measuring device 41. The phase of the current Iout2 is adjusted so that the peak position of the current Iout2 comes.

  Next, the control unit 212 operates the power conversion unit 13 so that the phase of the current Iout1 (Iout2) becomes the set phase (step S35).

  Thereafter, the control unit 212 continues the operation unless a power-off instruction is received (step S37: NO). On the other hand, the control part 212 will complete | finish operation | movement, if a power-off instruction | indication is received (step S37: YES).

Next, the behavior of the current flowing through the trunk line 151a of the line 151 and the line voltage Vdc in the power supply system 301 will be described. Here, a case where only one load conversion device 207A is operating and a case where two load conversion devices 207A and 207B are operating will be described.
FIG. 10 is an equivalent circuit showing the power supply system 301 according to the present embodiment.
As shown in FIG. 7, the power generation device 102 and the storage battery 106 are connected to a power generation device conversion device 103 and a storage battery conversion device 101 that function as a DC / DC converter. The AC power source 104 is connected to an AC power source converter 105 that functions as an AC / DC converter. Therefore, in FIG. 10, the power generation apparatus 102, the storage battery 106, and the AC power supply 104 are collectively represented as one current source (power supply) P.

First, a case where only one load conversion device 207A operates and the load conversion device 207B is stopped will be described. In this case, all the current output from the current source P is supplied to the load converter 207A.
FIG. 11 is a simulation result showing the line voltage Vdc, the input current Iinv1 to the load converter 207A, and the current Iout1 output from the load converter 207A in the power supply system 301 according to the present embodiment. .
As shown in FIG. 11, a ripple component exists in the input current Iinv1 to the load converter 207A. As a result, a ripple component corresponding to the current Iinv1 also exists in the line voltage Vdc.

By the way, the relational expression of the following formula (2) is established between the line voltage Vdc, the current Ig flowing out from the current source P, and the input current Iinv1 to the load converter 207A.

Here, C is the capacitance of the capacitor 109, Vdc (t) is the line voltage, Ig (t) is the current flowing out from the current source P, and Iinv1 (t) is the input to the load converter 207A. Indicates current.
As shown in Expression (2), the line voltage Vdc corresponds to a time-integrated difference between the current Ig and the current Iinv1. Therefore, a phase difference of 90 ° is generated between the line voltage Vdc, the current Ig, and the current Iinv1.

The relational expression (3) below is established between the input current Iinv1 to the load converter 207A and the current Iout1 output from the load converter 207A.

From the equations (2) and (3), it can be seen that the peak position of the current Iout1 output from the load converter 207A matches the peak position of the line voltage Vdc. In fact, this is also apparent from the simulation results of FIG.

Next, a case where two load conversion devices 207A and 207B are operating will be described. Here, the control unit 212 incorporated in the load converter 207B outputs the current output from the load converter 207B so as to reduce the ripple component generated in the current Iinv flowing through the trunk line 151a of the line 151 and the line voltage Vdc. The phase of Iout2 is set.
FIG. 12 is a simulation result showing the line voltage Vdc, the input current Iinv2 to the load converter 207B, and the current Iout1 output from the load converter 207B in the power supply system 301 according to the present embodiment. . In FIG. 12, for the line voltage Vdc, only one of the load conversion devices 207A is operating. Further, regarding currents Iinv2 and Iout2, a case is shown in which two load converters 207A and 207B are operating.

  In the load converter 207 </ b> B, the voltage measuring device 41 measures the line voltage Vdc as shown in FIG. 12 and inputs the measured value to the control unit 212. Then, based on the measurement value acquired from the voltage measuring device 41, the control unit 212 is arranged such that the peak position of the current Iout2 output from the load converter 207B is at the peak position of the line voltage Vdc. The phase of the current Iout2 is adjusted.

  As a result, when the direct currents flowing through the branch lines 151b are added, the direct current ripple components flowing through the respective branch lines 151b are substantially canceled by the direct current ripple components flowing through the other branch lines 151b. Therefore, the DC ripple component flowing through the main line 151a can be substantially eliminated.

FIG. 13 is a simulation result showing input currents Iinv1 and Iinv2 to the load converters 207A and 207B in the power supply system 301 according to the present embodiment.
As shown in FIG. 13, the waveform of the input current Iinv1 to the load converter 207A is a waveform that is shifted by approximately π from the input current Iinv2 to the load converter 207B.

FIG. 14 is a simulation result showing a current flowing through the trunk line 151a of the line 151 in the power supply system 301 according to the present embodiment. FIG. 14 also shows a simulation result when the current Iinv1 and the current Iinv2 are in phase (hereinafter referred to as “Comparative Example 2”).
Here, the current flowing through the trunk line 151a corresponds to a current obtained by adding the input current Iinv1 to the load converter 207A and the input current Iinv2 to the load converter 207B.
As shown in FIG. 14, in the comparative example 2, since the current Iinv1 and the current Iinv2 strengthen each other, the ripple component of the current flowing through the trunk line 151a is increased. On the other hand, in this embodiment, the ripple component of the input current Iinv1 is canceled out by the ripple component of the input current Iinv2, so that the ripple component of the current flowing through the trunk line 151a is reduced. As described above, the power supply system 301 according to the present embodiment has an advantage that the rated current of the line 151 can be reduced because the ripple component of the current flowing through the line 151 can be reduced. Moreover, since the ripple component superimposed on the current flowing through the line 151 can be reduced, voltage fluctuation of the line voltage Vdc can be suppressed accordingly.

FIG. 15 is a simulation result showing the line voltage Vdc in the power supply system 301 according to the present embodiment. FIG. 15 also shows a simulation result when the current Iinv1 and the current Iinv2 have the same phase (Comparative Example 2).
In Comparative Example 2, the ripple component of the line voltage Vdc increases with the increase of the ripple component of the current flowing through the trunk line 151a of the line 151.
On the other hand, in the present embodiment, the ripple component of the line voltage Vdc is also reduced as the ripple component of the current flowing through the trunk line 151a of the line 151 is reduced.

  As described above, in the power supply system 301 according to the present embodiment, the DC ripple component flowing through the main line 151a is reduced. As a result, the capacitance of the capacitor 109 that smoothes the direct current flowing through the main line 151a can be reduced, so that the power supply system 301 can be reduced in size and cost.

  Eventually, according to the power supply system 301 according to the present embodiment, when the two load conversion devices 207A and 207B are operating on the basis of the line voltage Vdc, other load conversion devices than their own devices are operating. If determined, the AC phase is set based on the line voltage Vdc. That is, the load conversion device 207A (207B) does not obtain information on the AC phase output from the other load conversion device 207B (207A) from the other load conversion device 207B (207A). Set the output AC phase. This eliminates the need for the load conversion device 207A (207B) to have a function of communicating with another load conversion device 207B (207A). Therefore, the configuration of the load conversion devices 207A and 207B can be simplified.

  Further, in the power supply system 301, when the load conversion device 207B is operating the other load conversion device 207A, the voltage fluctuation peak position of the voltage of the main line 151a and the own device supply the load device 108B. The AC phase is set so that the AC peak position matches. As a result, when the direct currents flowing through the branch lines 151b are added, the direct current ripple components flowing through the respective branch lines 151b are substantially canceled by the direct current ripple components flowing through the other branch lines 151b. Therefore, the DC ripple component flowing through the main line 151a can be substantially eliminated.

<Modification>
(1) In the first embodiment, an example is described in which one of the three load conversion devices 107A, 107B, and 107C that is first turned on is operated as a master unit, and the other two units are operated as slave units. However, the setting method of the parent device and the child device is not limited to this. For example, a configuration in which a parent device and a child device are set from among the three load conversion devices 107A, 107B, and 107C by the user's selection may be adopted.

(2) In the first embodiment, when the load conversion devices 107B and 107C operating as slave units receive the identification information of the load conversion device 107A, the identification information of the own device is transmitted to the load conversion device 107A. explained. However, the load conversion devices 107B and 107C operating as slave units are configured to transmit a response signal indicating that the identification information transmitted from the load conversion device 107A has been received instead of the identification information of the own device. May be.
Here, if the amount of information included in the response signal is made smaller than the amount of information included in the identification information, the amount of information exchanged between the load conversion devices 107A, 107B, and 107C can be reduced. Communication traffic between the converters 107A, 107B, and 107C can be reduced.

(3) In Embodiment 1, an example in which three load conversion devices are provided has been described. However, for example, a configuration in which two load conversion devices are provided or a configuration in which four or more load conversion devices are provided may be employed. In the second embodiment, an example in which two load conversion devices are provided has been described. However, for example, a configuration in which three or more load conversion devices are provided may be employed.

  The above-described embodiments and modifications should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

12, 212 Control unit 13 Power conversion unit 23 Gate drive circuit 24 Inverter circuit 31, 32, 33, 34 Transistor 35, 36 Coil 37, 109 Capacitor 41, 44 Voltage measuring device 42, 43 Current measuring device 101 Conversion device 102 for storage battery Power generation device 103 Conversion device for power generation device 104 AC power source 105 Conversion device for AC power source 106 Storage battery 107A, 107B, 107C, 207A, 207B Conversion device for load 108A, 108B, 108C Load device 110 Command unit 151 Line 151a Trunk line 151b Branch line 201, 301 Power supply system

Claims (7)

A power supply for supplying direct current to a line composed of a trunk line and a branch line connected to the trunk line;
A plurality of load conversion devices provided for each of a plurality of load devices, each having an inverter circuit that converts a direct current supplied from the main line through the branch line into an alternating current and supplies the alternating current to the load device;
A power supply system comprising:
The plurality of load conversion devices are shifted from each other in the phase of the alternating current supplied to the corresponding load device ,
There are N load conversion devices,
When the amount of phase shift of the alternating current input to the other load device with respect to the alternating current input to one of the plurality of load devices is φ, a relational expression shown in the following equation (1) is established,
In the plurality of load conversion devices, the load conversion device that is first turned on operates as a parent device, and the other load conversion devices operate as child devices,
A power supply system in which a load converter that operates as a base unit sets the phase shift amount .
A power supply for supplying direct current to a line composed of a trunk line and a branch line connected to the trunk line;
A plurality of load conversion devices provided for each of a plurality of load devices, each having an inverter circuit that converts a direct current supplied from the main line through the branch line into an alternating current and supplies the alternating current to the load device;
A power supply system comprising:
The plurality of load conversion devices are shifted from each other in the phase of the alternating current supplied to the corresponding load device ,
When each of the plurality of load conversion devices determines that another load conversion device other than its own device is operating based on the fluctuation range of the voltage of the line, the AC based on the voltage of the line Power supply system to set the phase of the . Wherein each of the plurality of load converter, claim set and the peak position of the voltage variation of the voltage of the line, the AC phase as the peak position of the AC supply to the own device is a load device matches 2 The power supply system described. The power supply is
A converter for a power generator that converts a direct current supplied from a power generator and supplies it to a line, a converter for an AC power supply that converts an alternating current supplied from an AC power source to a direct current and supplies the line to the line, and a storage battery power supply system according to claim 1 to claim 3, further comprising at least one of converting the DC storage battery converter to be supplied to the line. A power source that supplies direct current to a line composed of a main line and a branch line connected to the main line, and a plurality of load devices, each of which is provided with a load, converts the direct current supplied from the line into alternating current, and supplies the alternating current to the load device A power supply method using a power supply system including N (N is an integer of 2 or more) load converters having an inverter circuit,
There are N load conversion devices,
When the shift amount of the phase of the alternating current input to the other load device with respect to the alternating current input to one of the plurality of load devices is φ, the plurality of the plural expressions so that the relational expression shown in the following equation (1) holds look including the step of setting the phase of the AC input each load device,
In the plurality of load conversion devices, the load conversion device that is first turned on operates as a parent device, and the other load conversion devices operate as child devices,
A power supply method in which a load conversion device that operates as a base unit sets the phase shift amount .
A power source that supplies direct current to a line composed of a main line and a branch line connected to the main line, and a plurality of load devices, each of which is provided with a load, converts the direct current supplied from the line into alternating current, and supplies the alternating current to the load device A power supply method using a power supply system comprising a plurality of load conversion devices having an inverter circuit,
When each of the plurality of load conversion devices determines that another load conversion device other than its own device is operating based on the fluctuation range of the voltage of the line, the AC based on the voltage of the line A method for supplying power, comprising the step of setting the phase of A load conversion device provided for each of a plurality of load devices, having an inverter circuit that converts the direct current supplied from the line into alternating current and supplies the alternating current to the load device,
A control unit configured to set the phase of the alternating current based on the voltage of the line when it is determined that a load conversion device other than the own device is operating based on the fluctuation range of the voltage of the line;
Load converter.