JP7519282B2 - DC Power System - Google Patents

Description

This disclosure relates to a DC power supply system.

Distributed power supply systems that use electric vehicle batteries to supply power to loads are known. For example, the power supply system described in Patent Document 1 shows a configuration in which the amount of power supplied from the grid power supply is kept constant, while storage batteries, vehicle batteries, etc. are organically used to supply power to the load during a power outage.

JP 2015-76977 A

In recent years, there has been an increasing demand for communication infrastructure that does not lose power even during disasters, in order to strengthen disaster resistance. For this reason, the use of batteries from electric vehicles and other sources, in addition to storage batteries, as emergency power sources for wireless base stations has been considered. However, no consideration has been given to a method for ensuring a certain amount of storage in storage batteries as backup power sources, and for adjusting power while appropriately charging and discharging batteries for electric vehicles.

This disclosure has been made in light of the above, and aims to provide technology that enables a stable supply of power to a load while appropriately managing the amount of electricity stored in storage batteries and electric vehicle batteries.

In order to achieve the above object, a DC power supply system according to one embodiment of the present disclosure is a system that is connected to an electric vehicle that performs charging and discharging operations of a storage battery based on an external command, and controls the power supplied to a load that uses DC power, and includes a rectifier that converts AC power from a commercial power source into DC power, a load that consumes the DC power, a storage battery voltage confirmation unit that confirms the voltage of the storage battery, a voltage adjustment unit that adjusts the voltage of the power output from the rectifier, and a mode control unit that controls each unit based on an operation mode that is the state of power exchange between the commercial power source, the electric vehicle, the storage battery, and the load, selected based on the power demand of the load, the charging and discharging operations between the electric vehicle, and the storage battery voltage confirmed by the storage battery voltage confirmation unit, and the voltage adjustment unit adjusts the voltage of the power supplied from the rectifier based on the operation mode selected by the mode control unit.

According to the DC power supply system described above, the voltage of the power supplied from the rectifier is adjusted based on the operation mode selected based on the power demand of the load, the charging and discharging operation between the electric vehicle and the storage battery, and the storage battery voltage confirmed by the storage battery voltage confirmation unit. As a result, the power is controlled to be exchanged based on the selected operation mode. Since the operation mode is selected based on the storage battery voltage while charging and discharging the electric vehicle storage battery based on an external command, a stable power supply to the load is possible while appropriately managing the amount of electricity stored in the storage battery and the electric vehicle battery.

This disclosure provides technology that enables stable power supply to a load while appropriately managing the amount of stored power in storage batteries and electric vehicle batteries.

FIG. 1 is a diagram showing an example of a schematic configuration of a DC power supply system according to an embodiment. FIG. 2 is a block diagram illustrating an example of the function of a converter device in a DC power supply system. FIG. 3 is a block diagram illustrating an example of the function of the mode control unit in the DC power supply system. FIG. 4 is a diagram illustrating an example of a hardware configuration of the mode control unit. FIG. 5 is a flowchart showing an example of the operation of the charge/discharge switching unit in the DC power supply system. FIG. 6 is a flowchart showing an example of the operation of the mode control unit in the DC power supply system. FIG. 7 is a diagram showing an example of an operation mode during discharging of an electric vehicle. FIG. 8A is a diagram showing an example of the flow of power in an operation mode M1, and FIG. 8B is a diagram showing an example of the flow of power in an operation mode M2. FIG. 9A is a diagram showing an example of the flow of power in an operation mode M3, and FIG. 9B is a diagram showing an example of the flow of power in an operation mode M4. FIG. 10(a) is a diagram showing an example of power flow in operation mode M5, FIG. 10(b) is a diagram showing an example of power flow in operation mode M6, and FIG. 10(c) is a diagram showing an example of power flow in operation mode M7. FIG. 11 is a diagram showing an example of a process related to selection of an operation mode when discharging an electric vehicle. FIG. 12 is a diagram showing an example of an operation mode during charging of an electric vehicle. 13A is a diagram showing an example of the flow of power in an operation mode M8, and FIG. 13B is a diagram showing an example of the flow of power in an operation mode M9. 14A is a diagram showing an example of the flow of power in an operation mode M10, and FIG. 14B is a diagram showing an example of the flow of power in an operation mode M11. FIG. 15 is a diagram showing an example of a process related to selection of an operation mode when charging an electric vehicle. FIG. 16 is a diagram showing an example of an operation mode when the electric vehicle is in a standby state. FIG. 17A is a diagram showing an example of the flow of power in an operation mode M12, and FIG. 17B is a diagram showing an example of the flow of power in an operation mode M13. FIG. 18A is a diagram showing an example of the flow of power in an operation mode M14, and FIG. 18B is a diagram showing an example of the flow of power in an operation mode M15. FIG. 19 is a diagram showing an example of a process related to selection of an operation mode when the electric vehicle is in a standby state.

Embodiments of the present disclosure will be described in detail below with reference to the attached drawings. Note that in the description of the drawings, the same elements are given the same reference numerals and duplicate descriptions will be omitted.

[DC power supply system]
Fig. 1 is a block diagram showing an overview of a DC power supply system according to an embodiment. As shown in Fig. 1, the DC power supply system 1 includes a rectifier 2, a load 3, a storage battery 4, and a converter device 5. The rectifier 2 is connected to a commercial power supply 6, and the converter device 5 can be connected to an electric vehicle 7. The DC power supply system 1 is configured to be able to use power (external power) from the commercial power supply 6. A control device that controls the movement of power within the DC power supply system 1 is realized as a control unit 52 included in the converter device 5.

The rectifier 2 converts AC power from the commercial power source 6 into DC power. The load 3 is a load that receives DC power and operates. In this embodiment, the load 3 is a communication device, and includes, for example, a wireless base station. The load 3 differs from loads such as those in an ordinary home or office in that it consumes DC power.

In the DC power supply system 1, the storage battery 4 is charged with power (surplus power) that is not consumed by the load 3, among the power supplied from the commercial power source 6 or the electric vehicle 7. The storage battery 4 can also supply power to the load 3 or the electric vehicle 7 by discharging. For example, a lithium-ion storage battery can be used as the storage battery 4.

In the following embodiments, "electric vehicle 7" refers to an electric vehicle storage battery provided in electric vehicle 7. An electric vehicle is equipped with a storage battery for use in driving the vehicle, etc. When an electric vehicle is connected to DC power supply system 1, DC power supply system 1 may be involved in charging and discharging the storage battery. In the following embodiments, the storage battery provided in the electric vehicle may be described as "electric vehicle 7" to distinguish it from the "storage battery 4" provided in DC power supply system 1.

When a power outage occurs due to a disaster and power from the commercial power source 6 becomes unavailable, DC power can be supplied to the load 3 by using the electric vehicle 7 and the storage battery 4 as a backup power source.

Electric vehicle 7 has an internal storage battery. Therefore, electric vehicle 7 can supply power from the storage battery to load 3 or storage battery 4, and can be used as a power supply source in DC power supply system 1. On the other hand, electric vehicle 7 may be required to supply power to loads other than load 3 in DC power supply system 1. It may also be required to secure enough power to allow electric vehicle 7 itself to move. Electric vehicle 7 can receive and send power by connecting to DC power supply system 1 via converter device 5.

The converter device 5 has a function of adjusting the current and voltage when the DC power supply system 1 exchanges power with the electric vehicle 7. Power can be exchanged at high voltage between the DC power supply system 1 (converter device 5) and the electric vehicle 7. Meanwhile, within the DC power supply system 1, a bus line is provided that assumes transmission of power at a low voltage (e.g., 48 V). Therefore, power is exchanged with the electric vehicle 7 after voltage is adjusted in the converter device.

In this embodiment, a control device that controls the exchange of power between each part of the DC power supply system 1 is provided in the converter device 5. Therefore, as shown in FIG. 2, the converter device 5 essentially adjusts the exchange of power between the rectifier 2, the load 3, the storage battery 4, and the electric vehicle 7 in addition to performing power conversion assuming the exchange of power with the electric vehicle 7.

Next, with reference to Figure 2, we will explain the configuration of the converter device in the DC power supply system 1 and how it works with each part.

The converter device 5 is provided with a terminal T1 as a connection terminal with the rectifier 2. Similarly, a terminal T2 is provided as a connection terminal with the load 3, a terminal T3 is provided as a connection terminal with the storage battery 4, and a terminal T4 is provided as a connection terminal with the electric vehicle 7. A bus line is provided between the converter device 5 and the rectifier 2, the load 3, the storage battery 4, and the electric vehicle 7 to electrically connect them. The voltage of the bus line (bus voltage) may be controlled to a voltage (for example, 48 V) that does not exceed the rated voltage of the load 3 (for example, 57 V). The terminals T1 to T4 may be provided with a function to measure the voltage of the power passing through the terminal. For example, the measurement value of the power voltage measured at the terminal T2 may be sent to the mode control unit 56.

In the converter device 5, the bus lines (buses) from each terminal T1 to T4 are wired to converge at a single point P so that power can be exchanged between the rectifier 2, the load 3, the storage battery 4, and the electric vehicle 7. Therefore, power supplied from the commercial power source 6 via the rectifier 2 can be supplied to any of the load 3, the storage battery 4, and the electric vehicle 7. Similarly, power supplied from the storage battery 4 can be supplied to any of the load 3 and the electric vehicle 7, and power supplied from the electric vehicle 7 can be supplied to any of the load 3 and the storage battery 4.

The converter device 5 is configured to include a converter function unit 51 (converter unit) and a control unit 52. The converter function unit 51 is a part that performs the original function of a converter that adjusts the current and voltage when the DC power supply system 1 exchanges power with the electric vehicle 7. Furthermore, the converter function unit 51 is configured to include a charge/discharge switching unit 53 and a DC/DC conversion unit 54.

The charge/discharge switching unit 53 has the function of switching between charging and discharging with the electric vehicle 7 based on commands from the control unit 52.

The DC/DC conversion unit 54 has the function of adjusting the current and voltage of the power exchanged with the electric vehicle 7 (DC/DC conversion) based on commands from the control unit 52.

The control unit 52 has the function of acquiring information related to the operation of each unit, such as the power storage status, from the storage battery 4, the rectifier 2, and the electric vehicle 7, and controlling the charging and discharging of each unit and the power supply to the load 3 based on the acquired information. The control unit 52 is composed of a storage battery voltage confirmation unit 55, a mode control unit 56, and a voltage adjustment unit 57.

The battery voltage confirmation unit 55 measures the terminal voltage of the battery 4 (terminal voltage _VLIB ; hereinafter, sometimes referred to as battery voltage _VLIB ). The terminal voltage of the battery 4 is related to the SOC (State Of Charge; remaining capacity) as the amount of stored electricity. The battery voltage confirmation unit 55 measures the terminal voltage of the battery 4 as information related to the remaining capacity of the battery 4. In the following description, the terminal voltage of the battery 4 may be referred to as the "battery voltage."

The mode control unit 56 has the function of setting an operation mode that specifies the movement of power in the DC power supply system 1 based on the charge/discharge state of the electric vehicle 7 and the terminal voltage of the storage battery 4. The operation modes will be described in detail later.

The voltage adjustment unit 57 has a function of adjusting the voltage of the DC power supplied from the rectifier 2 based on a command from the mode control unit 56. By adjusting the voltage of the DC power, the transfer of power in the DC power supply system 1 can be controlled.

Next, the mode control unit 56 will be described with reference to FIG. 3. As shown in FIG. 3, the mode control unit 56 includes an EV operation information acquisition unit 501, a storage battery voltage information acquisition unit 502, an operation mode determination unit 503, and a rectifier voltage command unit 504.

The EV operation information acquisition unit 501 has a function of acquiring operation information related to charging, discharging, and standby of the electric vehicle 7 (the storage battery in the electric vehicle 7). The electric vehicle 7 can supply power to the load 3 by discharging from the storage battery while connected to the DC power supply system 1. On the other hand, the electric vehicle 7 may be required to move to a place where another load is installed and supply power to the other load. Therefore, the electric vehicle 7 is required to have a certain amount of stored power. The operation content (charging, discharging, standby) of the electric vehicle 7 when connected to the DC power supply system 1 is specified in advance by an external command or the like. The external command may be, for example, a command from a user of the electric vehicle 7, or may be determined based on a judgment logic or the like provided inside the electric vehicle 7. Here, "outside" indicates that it is not inside the DC power supply system 1. The DC power supply system 1 is required to charge and discharge the electric vehicle 7 based on this external command.

In the electric vehicle 7, the lower limit (minimum amount of stored electricity) and upper limit (maximum amount of stored electricity) of the storage battery may be determined in advance, and charging, discharging, etc. may be performed within that range.

The battery voltage information acquisition unit 502 has a function of monitoring the amount of electricity stored in the battery 4. The battery voltage information acquisition unit 502 acquires the measurement result of the voltage (battery voltage) in the battery voltage confirmation unit 55. This measurement result is used to determine the operation content in the operation mode determination unit 503 (determine the command content from the mode control unit 56).

The operation mode determination unit 503 has a function of determining the operation mode of the DC power supply system 1 based on the information sent from the EV operation information acquisition unit 501 and the storage battery voltage information acquisition unit 502. Details of the type of operation mode and how the operation mode is determined will be described later.

The rectifier voltage command unit 504 has a function of issuing a command related to voltage to the voltage adjustment unit 57 based on the operation mode determined by the operation mode determination unit 503. The command to the voltage adjustment unit 57 is information specifying the voltage of the DC power supplied from the rectifier 2 to the DC power supply system 1. The output voltage from the rectifier 2 (rectifier output voltage V _RF ; hereinafter, sometimes referred to as rectifier voltage V _RF ) can be adjusted by controlling the circuit constituting the rectifier 2. When the rectifier voltage command unit 504 transmits a command to set the output voltage to the voltage adjustment unit 57, the voltage adjustment unit 57 changes the control of the circuit in the rectifier 2. As an example, the rectifier voltage command unit 504 issues a command to the rectifier 2 to change the circuit so that the output voltage becomes a predetermined output voltage. As a result, the rectifier 2 sets the voltage of the power to be output toward the load 3. At this time, the rectifier voltage command unit 504 may be configured to change the content of the command to the voltage adjustment unit 57 while monitoring the voltage of the power from the rectifier 2 measured at the terminal T2.

In the above DC power supply system 1, as an example, it is assumed that the load 3 is a communication device that is part of the communication infrastructure and consumes a certain amount of power at all times. Therefore, it is necessary to continuously supply a certain amount of power to the load 3 by utilizing power from the commercial power source 6. On the other hand, the storage battery 4 can function as a backup power source to enable a long-term power supply to the load 3 when a power outage occurs due to a disaster (enabling communication services to continue for a certain period of time even in an emergency). Therefore, it is required to keep the SOC of the storage battery 4 relatively high so that it can be used as an emergency power source in the event of a disaster.

When electric vehicle 7 is connected, DC power supply system 1 also controls charging and discharging of electric vehicle 7. Electric vehicle 7 is required to store the power required for traveling as a vehicle and for discharging to a load at the destination. On the other hand, when the amount of stored power in electric vehicle 7 is large, it is possible to supply power to DC power supply system 1 by discharging. Therefore, the SOC of electric vehicle 7 is also required to be adjusted within a certain range.

Therefore, the DC power supply system 1 controls the transfer of power between the electric vehicle 7, the storage battery 4, and the load 3 by adjusting the power voltage from the commercial power source 6 while taking into consideration the amount of electricity stored in the storage battery 4 and the operation (charging, discharging, or standby) performed by the electric vehicle 7 while connected to the DC power supply system 1. When the electric vehicle 7 is connected to the DC power supply system 1, the state of power exchange (charging, discharging, or standby) is determined in advance. Therefore, the DC power supply system 1 controls the charging and discharging of the storage battery 4 and the supply of power to the load 3 based on this information while maintaining the power exchange state of the electric vehicle 7.

The hardware configuration of the mode control unit 56 will be described with reference to FIG. 4. As shown in FIG. 4, the mode control unit 56 may be physically configured as a computer device including a processor C1, a memory C2, a storage C3, a communication device C4, an input device C5, an output device C6, a bus C7, etc.

In the following description, the term "apparatus" may be interpreted as a circuit, device, unit, etc. The hardware configuration of the mode control unit 56 may be configured to include one or more of the devices shown in FIG. 4. It may also be configured to exclude some of the devices.

Each function in the mode control unit 56 is realized by loading specific software onto hardware such as the processor C1 and memory C2, which causes the processor C1 to perform calculations and control communications via the communication device C4, and the reading and/or writing of data in the memory C2 and storage C3.

The processor C1, for example, runs an operating system to control the entire computer. The processor C1 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control unit, an arithmetic unit, and registers. The processor C1 may also be configured to include a GPU (Graphics Processing Unit). For example, the functional units (501 to 504) shown in FIG. 3 may be realized by the processor C1.

The processor C1 also reads out programs (program codes), software modules and data from the storage C3 and/or the communication device C4 into the memory C2, and executes various processes according to these. The programs used are those that cause a computer to execute at least some of the operations described in the above-mentioned embodiment. For example, the functional units (501-504) of the mode control unit 56 may be stored in the memory C2 and realized by a control program that runs on the processor C1. Although the above-mentioned various processes have been described as being executed by one processor C1, they may be executed simultaneously or sequentially by two or more processors C1. The processor C1 may be implemented in one or more chips. The programs may be transmitted from a network via a telecommunications line.

Memory C2 is a computer-readable recording medium, and may be composed of at least one of, for example, ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), etc. Memory C2 may also be called a register, cache, main memory (primary storage device), etc. Memory C2 can store executable programs (program codes), software modules, etc. for implementing a control method according to one embodiment of the present disclosure.

Storage C3 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray (registered trademark) disk), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy (registered trademark) disk, a magnetic strip, etc. Storage C3 may be referred to as an auxiliary storage device. The above-mentioned storage medium may be, for example, a database, a server, or other suitable medium including memory C2 and/or storage C3.

The communication device C4 is hardware (transmitting/receiving device) for communicating between computers via a wired and/or wireless network, and is also referred to as, for example, a network device, a network controller, a network card, a communication module, etc.

The input device C5 is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that accepts input from the outside. The output device C6 is an output device (e.g., a display, a speaker, an LED lamp, etc.) that performs output to the outside. Note that the input device C5 and the output device C6 may be integrated into one structure (e.g., a touch panel).

In addition, each device, such as the processor C1 and the memory C2, is connected by a bus C7 for communicating information. The bus C7 may be configured as a single bus, or may be configured as different buses between the devices.

The control unit 52 may also be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized by the hardware. For example, the processor C1 may be implemented by at least one of these pieces of hardware.

[Charge/Discharge Control Overview]
(Operation of the charge/discharge switching unit)
5 is a flowchart showing an example of processing performed by the charge/discharge switching unit 53 in response to the charge/discharge setting of the electric vehicle 7. The processing shown in FIG.

In step S01, the charge/discharge switching unit 53 checks whether there is an operational command for power transfer for the electric vehicle 7 connected to the DC power supply system 1. An operational command for power transfer is, for example, information instructing the electric vehicle 7 to discharge or charge. If there is no operational command (S01-NO), the electric vehicle 7 goes into a standby state in which it does not transfer power to or from other devices such as the load 3, even if it is connected to the DC power supply system 1. If there is an operational command (S01-YES), in step S02, it is determined whether the operational command is a discharge command.

If the operation command for the electric vehicle 7 is a discharge command (S02-YES), in step S03, the charge/discharge switching unit 53 performs an operation to discharge from the electric vehicle 7 (discharging operation). On the other hand, if the operation command for the electric vehicle 7 is not a discharge command, i.e., a charge command (S02-NO), in step S04, the charge/discharge switching unit 53 performs an operation to charge from the electric vehicle 7 (charging operation).

In this way, the charge/discharge switching unit 53 operates according to the presence or absence of an operation command for the electric vehicle 7 connected to the DC power supply system 1 and the type of command. Then, in step S05, the charge/discharge switching unit 53 transmits a signal related to the operation settings of the electric vehicle 7 to the mode control unit 56.

(Operation of the mode control section)
Fig. 6 is a flowchart showing an example of an operation executed under the control of the mode control unit 56. The process shown in Fig. 6 is performed, for example, when the mode control unit 56 receives a signal transmitted from the charge/discharge switching unit 53 after the electric vehicle 7 is connected to the DC power supply system 1.

First, in step S11, it is confirmed whether there is an operation command related to charging or discharging the electric vehicle 7 based on information from the charge/discharge switching unit 53 acquired by the EV operation information acquisition unit 501 of the mode control unit 56.

If there is an operation command related to charging/discharging the electric vehicle 7 (S11-YES), in step S12, it is determined whether the operation command is a discharge command. If the operation command related to the electric vehicle 7 is a discharge command (S12-YES), in step S13, the mode control unit 56 selects one operation mode from multiple operation modes for discharging from the electric vehicle 7. On the other hand, if the operation command related to the electric vehicle 7 is not a discharge command, i.e., a charge command (S12-NO), in step S14, the mode control unit 56 selects one operation mode from multiple operation modes for discharging from the electric vehicle 7.

If there is no operation command (S11-NO), the electric vehicle 7 is placed in a standby state in which it does not exchange power with other devices such as the load 3, even if it is connected to the DC power supply system 1. In this case, in step S15, the mode control unit 56 selects one operation mode from multiple operation modes when the electric vehicle 7 is in a standby state.

After the operation mode is selected according to the above procedure, in step S16, a signal corresponding to the selected operation mode is transmitted from the rectifier voltage command unit 504 of the mode control unit 56 to the voltage adjustment unit 57. Based on the signal corresponding to the operation mode acquired in step S16, the voltage adjustment unit 57 controls the output voltage from the rectifier 2 so that it is within a predetermined range.

In this way, the mode control unit 56 selects the operation mode depending on the presence or absence of an operation command for the electric vehicle 7 connected to the DC power supply system 1 and the type of the command. When selecting the operation mode, the storage battery voltage measured by the storage battery voltage confirmation unit 55 is taken into consideration. Below, we will explain the operation mode that is set depending on the charge/discharge state of the electric vehicle 7.

(EV discharging operation mode)
Fig. 7 is a diagram showing a list of operation modes in the DC power supply system 1 when discharging from the electric vehicle 7. Figs. 8 to 10 show the flow of power in each operation mode.

As shown in FIG. 7, seven states M1 to M7 can be assumed as operation modes assuming discharging from the electric vehicle 7. In FIG. 7, the above-mentioned M1 to M7 are shown as modes, and the flow of power and supplementary explanations are shown corresponding to each operation mode. The flow of power indicates which device in the DC power supply system 1 and its surroundings the power flows from to which device. In addition, a simple illustration of the power flow in each mode is provided as supplementary explanations. Note that in FIG. 7 (and FIG. 12 and FIG. 16 described below), the rectifier 2 may be shown as RF, the electric vehicle 7 as EV, the storage battery 4 as LIB, and the load 3 as LOAD.

In FIG. 7, the operation mode M1 is described as "RF+EV+LIB→LOAD" as the flow of power. This indicates that power is supplied from all of the rectifier 2, the electric vehicle 7 (converter 5), and the storage battery 4 to the load 3, as shown in FIG. 8(a). In other words, the operation mode M1 is an assisted operation in which LIB is added to RF+EV. For example, as shown in FIG. 8(a), this operation mode M1 can be realized by setting the output voltage from the rectifier 2 to 50V when the storage battery voltage in the storage battery 4 is 50V and the output voltage from the electric vehicle 7 is 55V. The voltage values are examples, and the flow of power shown in FIG. 8(a) is realized by setting the storage battery voltage in the storage battery 4, the output voltage from the electric vehicle 7, and the output voltage from the rectifier 2 to the above relationship. The setting examples of the storage battery voltage in the storage battery 4, the output voltage from the electric vehicle 7, and the output voltage from the rectifier 2 are examples, and the same is true for other operation modes described below. The output voltage from the electric vehicle 7 is determined in advance and is not adjusted by the DC power supply system 1.

In FIG. 7, the flow of power in the operation mode M2 is described as "RF+EV→LIB+LOAD". This indicates that power is supplied from the rectifier 2 and the electric vehicle 7 (converter 5) to the storage battery 4 and the load 3, as shown in FIG. 8(b). In other words, the operation mode M2 is an assisted operation including power supply from RF to LIB. For example, as shown in FIG. 8(b), the operation mode M2 can be realized by setting the output voltage from the rectifier 2 to 50V when the storage battery voltage in the storage battery 4 is 45V and the output voltage from the electric vehicle 7 is 55V. At this time, the voltage difference between the output power from the rectifier 2 and the storage battery voltage in the storage battery 4 is set to 5V, but this difference is a value that can be determined to have a sufficient power difference between the two. In the case of a configuration assuming transmission of power at a low voltage of 48V, as in the configuration of this embodiment, a voltage difference of 3V or more can be recognized as a sufficient difference.

In FIG. 7, the power flow of operation mode M3 is described as "EV → LIB + LOAD". This indicates that power is supplied from the electric vehicle 7 (converter 5) to the storage battery 4 and the load 3, as shown in FIG. 9(a). In other words, operation mode M3 is an operation in which surplus power in the EV is supplied to the LIB. For example, as shown in FIG. 9(a), this operation mode M3 can be realized by setting the output voltage from the rectifier 2 to 45 V when the storage battery voltage in the storage battery 4 is 45 V and the output voltage from the electric vehicle 7 is 55 V. In this case, the power from the rectifier 2 (commercial power source 6) is not used to supply power to the load 3, etc.

In FIG. 7, the operation mode M4 is described as "RF+EV→LOAD" as the flow of power. This indicates that power is supplied from the rectifier 2 and the electric vehicle 7 (converter 5) to the load 3, as shown in FIG. 9(b). In other words, the operation mode M3 is an assist operation that assists the supply to the load by RF. For example, as shown in FIG. 9(b), this operation mode M4 can be realized by setting the output voltage from the rectifier 2 to 52V when the storage battery voltage in the storage battery 4 is 50V and the output voltage from the electric vehicle 7 is 55V. In this case, the power from the rectifier 2 can be supplied to the load 3 without flowing to the storage battery 4. In other words, a state is formed in which the power from the rectifier 2 is used preferentially for the load 3 by increasing the output voltage from the rectifier 2 by a small amount (ΔV) relative to the storage battery voltage. Here, the power difference is set to 2V, but this difference may be even smaller (about 0.1V to 2V). Ideally, by reducing ΔV to about 0.1 V, it is possible to create a state in which power from the rectifier 2 is supplied to the load 3 without flowing to the storage battery 4.

In FIG. 7, the power flow of operation mode M5 is described as "EV+LIB→LOAD". This indicates that power is supplied from the electric vehicle 7 (converter 5) and the storage battery 4 to the load 3, as shown in FIG. 10(a). In other words, operation mode M5 is an assist operation that assists the power supply from the LIB to the load. This operation mode M5 can be realized, for example, by setting the output voltage from the rectifier 2 to 45 V when the storage battery voltage in the storage battery 4 is 50 V and the output voltage from the electric vehicle 7 is 55 V, as shown in FIG. 10(a).

In FIG. 7, the flow of power in operation mode M6 is described as "EV→LOAD". This indicates that power is supplied from the electric vehicle 7 (converter 5) to the load 3, as shown in FIG. 10(b). In other words, operation mode M6 is EV-only operation in which only power is supplied from the EV to the load. This operation mode M6 can be realized, for example, by setting the output voltage from the rectifier 2 to 50 V when the battery voltage in the storage battery 4 is 50 V and the output voltage from the electric vehicle 7 is 55 V, as shown in FIG. 10(b).

In FIG. 7, the power flow of operation mode M7 is described as "RF→LIB, EV→LOAD". This indicates that, as shown in FIG. 10(c), power is supplied independently from the rectifier 2 to the storage battery 4 and from the electric vehicle 7 (converter 5) to the load 3. In other words, in operation mode M7, in addition to EV independent operation in which only power is supplied from the EV to the load, LIB charging is performed from a commercial power source (RF). This operation mode M7 can be realized, for example, by setting the output voltage from the rectifier 2 to 50V when the storage battery voltage in the storage battery 4 is 45V and the output voltage from the electric vehicle 7 is 55V, as shown in FIG. 10(c).

Of the seven operating modes, the operating modes M1, M3, and M6 all satisfy the relationship of "output voltage from electric vehicle 7 > storage battery voltage in storage battery 4 = output voltage from rectifier 2." In the DC power supply system 1, transitions between these operating modes can be made depending on the magnitude of the power to be supplied to the load 3. As an example, when the power used by the load 3 is large, power flows as in the operating mode M1, but when power can be supplied to the load 3 using only the power from the electric vehicle 7, power from the rectifier 2 is not required as in the operating mode M6. Furthermore, when the storage battery 4 can be charged and the load 3 can be supplied with power only from the electric vehicle 7, the storage battery 4 is also charged as in the operating mode M3. In this way, the operating modes M1, M3, and M6 are modes that can be transitioned depending on the power consumed in the load 3.

Furthermore, both operation modes M2 and M7 satisfy the relationship "output voltage from electric vehicle 7 > output voltage from rectifier 2 > storage battery voltage in storage battery 4." As an example, when the power used by load 3 is large, power from rectifier 2 is also supplied to load 3 as in operation mode M7. On the other hand, when the power used by load 3 is small and the power from electric vehicle 7 is sufficient, power from rectifier 2 and electric vehicle 7 flows to storage battery 4 as in operation mode M2. In this way, operation modes M2 and M7 are modes that can be transitioned depending on the power consumed by load 3.

Note that operation mode M4 is a mode that can be easily changed from operation mode M6, for example. For example, operation mode M6 indicates a state in which power is supplied to load 3 using only power from electric vehicle 7, but if the power usage (power demand) of load 3 increases, the output power from rectifier 2 can be increased by a small amount (for example, ΔV = about 0.1 to 2 V) and the output power from rectifier 2 can be added to load 3, so that power can be appropriately supplied to load 3. In this case, if the power usage of load 3 increases further, for example, the output voltage from rectifier 2 can be matched with the storage battery voltage to transition to operation mode M1.

Operation mode M5 can also be said to be a mode that is easy to change from operation mode M6, for example. For example, operation mode M6 indicates a state in which power is supplied to load 3 using only power from electric vehicle 7, but if the power consumption of load 3 increases, changing to operation mode M5 adds power from storage battery 4 to the supply to load 3, and power can be appropriately supplied to load 3. In this case, if the power consumption of load 3 increases further, for example, the output voltage from rectifier 2 may be matched with the storage battery voltage to transition to operation mode M1. Also, if the power consumption of load 3 decreases and the storage battery voltage decreases due to continued power to load 3, a transition to operation mode M3 may occur.

In this way, the operation modes M1 to M7 are not independent of each other, but can be changed organically depending on the power used by the load 3, etc. Also, among the operation modes M1 to M7, the operation modes M1, M4, M5, and M6 have a storage battery voltage of 50V, and can be said to be states in which discharging from the storage battery 4 is possible. On the other hand, the operation modes M2, M3, and M7 have a storage battery voltage of 45V, and can be said to be states in which discharging from the storage battery 4 is not possible. Taking such situations into consideration, the mode control unit 56 can select an operation mode.

Figure 11 shows, as an example, the procedure for specifying the output voltage from rectifier 2 after selecting the operating mode in advance.

First, in step S21, the start of the discharge operation is confirmed based on information from the charge/discharge switching unit 53 acquired by the EV operation information acquisition unit 501 of the mode control unit 56.

Next, in step S22, the storage battery voltage information acquisition unit 502 of the mode control unit 56 checks the voltage of the storage battery 4 based on the measurement result of the voltage (storage battery voltage) in the storage battery voltage check unit 55.

Next, in step S23, the operation mode determination unit 503 of the mode control unit 56 selects an operation mode from the above-mentioned operation modes M1 to M7 according to the current operation status of the DC power supply system 1. When determining the operation mode, for example, the power demand (power consumption status) of the load 3 may also be taken into consideration. Information related to the power demand of the load 3 may be obtained by the mode control unit 56, for example, from a notification from the load 3. Also, a prediction related to the power demand may be made in advance within the mode control unit 56.

Among these, when the operation modes M2 and M7 are selected, in step S24, the rectifier voltage _{VRF is set so that the rectifier voltage VRF is} sufficiently larger (for example, 3 V or more) than the storage battery voltage _VLIB ( _VRF > _VLIB ). The set rectifier voltage _VRF is transmitted as a command from the rectifier voltage command unit 504 to the voltage adjustment unit 57, and the rectifier voltage is adjusted in the voltage adjustment unit 57 (step S16).

Furthermore, when the operation mode M5 is selected, in step S25, the rectifier voltage VRF is set so that the rectifier voltage _{VRF is smaller than the storage battery voltage VLIB (VRF < VLIB). The set rectifier voltage VRF is transmitted as a} command from the rectifier voltage command unit 504 to the voltage adjustment unit 57, and the rectifier voltage is adjusted in the voltage adjustment unit 57 (step S16).

Furthermore, when the operation modes M1, M3, and M6 are selected, in step S26, the rectifier voltage _VRF is set so that the storage battery voltage _VLIB and the rectifier voltage _VRF have the same value ( _VRF = _VLIB ). The set rectifier voltage _VRF is transmitted as a command from the rectifier voltage command unit 504 to the voltage adjustment unit 57, and the rectifier voltage is adjusted in the voltage adjustment unit 57 (step S16).

Furthermore, when operation mode M4 is selected, in step S27, the rectifier voltage V RF is set so that the rectifier voltage V _RF is slightly (by a small amount) larger than the storage battery voltage V _LIB (V _RF = V _LIB + ΔV). _ΔV at this time is, for example, about 0.1 V to 2 V. The set rectifier voltage V _RF is transmitted as a command from rectifier voltage command unit 504 to voltage adjustment unit 57, and the rectifier voltage is adjusted in voltage adjustment unit 57 (step S16).

The selection of the operating mode may be repeated. For example, one of steps S24 to S27 may be selected and a command issued to the voltage adjustment unit 57 (step S16). After that, after a predetermined time, the steps of checking the storage battery voltage (step S22) to selecting the mode (step S23) may be repeated again, and the rectifier voltage may be adjusted (step S16).

(EV charging operation mode)
Fig. 12 is a diagram showing a list of operation modes in the DC power supply system 1 when charging the electric vehicle 7. Fig. 13 and Fig. 14 show the flow of power in each operation mode.

As shown in FIG. 12, four states M8 to M11 can be assumed as operating modes when discharging from the electric vehicle 7. In FIG. 12, the above-mentioned M8 to M11 are shown as modes, and the flow of power and supplementary explanations are shown corresponding to each operating mode.

In FIG. 12, the power flow for operation mode M8 is described as "RF→EV+LIB+LOAD." This indicates that power is supplied from the rectifier 2 to the electric vehicle 7 (converter 5), storage battery 4, and load 3, as shown in FIG. 13(a). In other words, operation mode M8 is a mode in which not only the electric vehicle 7 but also the storage battery (LIB) is charged. For example, as shown in FIG. 13(a), this operation mode M8 can be realized by setting the output voltage from the rectifier 2 to 50V when the storage battery voltage in the storage battery 4 is 45V. Since it is specified that charging is performed for the electric vehicle 7, there is no output voltage setting. This is also true for operation modes M9 to M11.

In FIG. 12, the operation mode M9 is described as "RF→EV+LOAD" as the flow of power. This indicates that power is supplied from the rectifier 2 to the electric vehicle 7 (converter 5) and the load 3, as shown in FIG. 13(b). In other words, the operation mode M9 is a mode in which the storage battery 4 (LIB) is not charged or discharged, and can be said to be an independent operation by the rectifier 2. For example, as shown in FIG. 13(b), this operation mode M9 can be realized by setting the output voltage from the rectifier 2 to 52V when the storage battery voltage in the storage battery 4 is 50V. In this case, the power from the rectifier 2 can be supplied to the load 3 without flowing to the storage battery 4. In other words, a state is formed in which the output voltage from the rectifier 2 is made slightly larger (ΔV) than the storage battery voltage, so that the power from the rectifier 2 is preferentially used for the load 3. Here, the power difference is set to 2V, but this difference may be even smaller (about 0.1V to 2V). Ideally, by reducing ΔV to about 0.1 V, it is possible to create a state in which power from the rectifier 2 is supplied to the load 3 without flowing to the storage battery 4.

In FIG. 12, the power flow of operation mode M10 is described as "RF+LIB→EV+LOAD". This indicates that power is supplied from the rectifier 2 and the storage battery 4 to the electric vehicle 7 (converter 5) and the load 3, as shown in FIG. 14(a). In other words, operation mode M10 is an operation in which the storage battery 4 assists the power supply from the rectifier 2. This operation mode M10 can be realized, for example, by setting the output voltage from the rectifier 2 to 50 V when the storage battery voltage in the storage battery 4 is 50 V, as shown in FIG. 14(a).

In FIG. 12, the power flow of the operation mode M11 is described as "LIB→EV+LOAD." This indicates that power is supplied from the storage battery 4 to the electric vehicle 7 (converter 5) and the load 3, as shown in FIG. 14(b). In other words, the operation mode M11 is an operation in which the storage battery 4 (LIB) supplies power to the load. This operation mode M11 can be realized, for example, by setting the output voltage from the rectifier 2 to 45 V when the storage battery voltage in the storage battery 4 is 50 V, as shown in FIG. 14(b).

Figure 15 shows, as an example, the procedure for specifying the output voltage from the rectifier 2 after selecting an operating mode in advance under the condition that the electric vehicle 7 is set to charge.

First, in step S31, the start of charging operation is confirmed based on information from the charge/discharge switching unit 53 acquired by the EV operation information acquisition unit 501 of the mode control unit 56.

Next, in step S32, the storage battery voltage information acquisition unit 502 of the mode control unit 56 checks the voltage of the storage battery 4 based on the measurement result of the voltage (storage battery voltage) in the storage battery voltage check unit 55.

Next, in step S33, the operation mode determination unit 503 of the mode control unit 56 selects an operation mode from the above-mentioned operation modes M8 to M11 according to the current operation status of the DC power supply system 1. When determining the operation mode, for example, the power demand (power consumption status) of the load 3 may also be taken into consideration.

Among these, when the operation mode M8 is selected, in step S34, the rectifier voltage _VRF is set so that the rectifier voltage _VRF is sufficiently larger (for example, 3 V or more) than the storage battery voltage _VLIB ( _VRF > _VLIB ). The set rectifier voltage _VRF is transmitted as a command from the rectifier voltage command unit 504 to the voltage adjustment unit 57, and the rectifier voltage is adjusted in the voltage adjustment unit 57 (step S16).

Moreover, when the operation mode M11 is selected, in step S35, the rectifier voltage VRF is set so that the rectifier voltage _{VRF is smaller than the storage battery voltage VLIB (VRF < VLIB). The set rectifier voltage VRF is transmitted as a} command from the rectifier voltage command unit 504 to the voltage adjustment unit 57, and the rectifier voltage is adjusted in the voltage adjustment unit 57 (step S16).

Moreover, when the operation mode M10 is selected, in step S36, the rectifier voltage VRF is set so that the storage battery voltage _VLIB and the rectifier voltage _{VRF have the same value (VRF = VLIB). The set rectifier voltage VRF is transmitted as} a command from the rectifier voltage command unit 504 to the voltage adjustment unit 57, and the rectifier voltage is adjusted in the voltage adjustment unit 57 (step S16).

Furthermore, when the operation mode M9 is selected, in step S37, the rectifier voltage VRF is set so that the rectifier voltage _VRF is slightly larger than the storage battery voltage _VLIB ( _VRF = _VLIB + ΔV). ΔV at this time is, for example, about 0.1 _{V to 2 V. The set rectifier voltage VRF is} transmitted as a command from the rectifier voltage command unit 504 to the voltage adjustment unit 57, and the rectifier voltage is adjusted in the voltage adjustment unit 57 (step S16).

The selection of the operating mode may be repeated. For example, one of steps S34 to S37 may be selected and a command issued to the voltage adjustment unit 57 (step S16). After that, after a predetermined time, the steps of checking the storage battery voltage (step S32) and selecting the mode (step S33) may be repeated again, and the rectifier voltage may be adjusted (step S16).

(EV standby operation mode)
Fig. 16 is a diagram showing a list of operation modes in the DC power supply system 1 when the electric vehicle 7 is not charging or discharging (is in a standby state). Figs. 17 and 18 show the flow of power in each operation mode.

As shown in FIG. 16, four operating modes, M12 to M15, can be assumed when electric vehicle 7 is in standby. In FIG. 16, the above-mentioned M12 to M15 are shown as modes, and the flow of power and supplementary explanations are shown in association with each operating mode.

In FIG. 16, the flow of power in operation mode M12 is written as "RF→LIB+LOAD". This indicates that power is supplied from rectifier 2 to storage battery 4 and load 3, as shown in FIG. 17(a). In other words, operation mode M12 is a mode in which the storage battery (LIB) is charged while power is being supplied to load 3. For example, as shown in FIG. 17(a), this operation mode M12 can be realized by setting the output voltage from rectifier 2 to 50V when the storage battery voltage in storage battery 4 is 45V. As it is specified that charging and discharging is not performed for electric vehicle 7 in the standby state, no power is exchanged between electric vehicle 7 and operation mode M12. This is the same for operation modes M12 to M15.

In FIG. 16, the operation mode M13 is described as "RF→LOAD" as the flow of power. This indicates that power is supplied from the rectifier 2 to the load 3, as shown in FIG. 17(b). In other words, the operation mode M13 is a mode in which the storage battery 4 (LIB) is not charged or discharged, and can be said to be an independent operation by the rectifier 2. For example, as shown in FIG. 17(b), this operation mode M13 can be realized by setting the output voltage from the rectifier 2 to 52V when the storage battery voltage in the storage battery 4 is 50V. In this case, the power from the rectifier 2 can be supplied to the load 3 without flowing to the storage battery 4. In other words, the output voltage from the rectifier 2 is increased by a small amount (ΔV) relative to the storage battery voltage, thereby forming a state in which the power from the rectifier 2 is used preferentially for the load 3. Here, the power difference is set to 2V, but this difference may be even smaller (about 0.1V to 2V). Ideally, by reducing ΔV to about 0.1 V, it is possible to create a state in which power from the rectifier 2 is supplied to the load 3 without flowing to the storage battery 4.

In FIG. 16, the operation mode M14 is described as "LIB→LOAD" as the flow of power. This indicates that power is supplied from the storage battery 4 to the load 3, as shown in FIG. 18(a). In other words, the operation mode M14 can be said to be an independent operation in which the storage battery 4 supplies power to the load 3. For example, as shown in FIG. 18(a), this operation mode M14 can be realized by setting the output voltage from the rectifier 2 to 45V when the storage battery voltage in the storage battery 4 is 50V. Note that the operation mode M14 is a mode that can operate even when, for example, a power outage occurs and the power transmission from the rectifier 2 is cut off (when the output voltage becomes 0V). Therefore, the operation mode M14 may be configured to automatically change the setting when the power transmission from the rectifier 2 is disabled, for example.

In FIG. 16, the power flow of operation mode M15 is written as "RF+LIB→LOAD". This indicates that power is supplied from the rectifier 2 and the storage battery 4 to the load 3, as shown in FIG. 18(b). In other words, operation mode M15 is an operation in which the storage battery 4 (LIB) assists in the power supply from the rectifier 2 to the load 3. This operation mode M15 can be realized, for example, by setting the output voltage from the rectifier 2 to 50 V when the storage battery voltage in the storage battery 4 is 50 V, as shown in FIG. 18(b).

Figure 19 shows, as an example, the procedure for specifying the output voltage from the rectifier 2 after selecting an operating mode in advance under the condition that the electric vehicle 7 is set to be in standby (not charging or discharging).

First, in step S41, based on information from the charge/discharge switching unit 53 acquired by the EV operation information acquisition unit 501 of the mode control unit 56, it is confirmed that no charge/discharge operation will be performed (the unit will be in standby mode).

Next, in step S42, the storage battery voltage information acquisition unit 502 of the mode control unit 56 checks the voltage of the storage battery 4 based on the measurement result of the voltage (storage battery voltage) in the storage battery voltage check unit 55.

Next, in step S43, the operation mode determination unit 503 of the mode control unit 56 selects an operation mode from the above-mentioned operation modes M12 to M15 according to the current operation status of the DC power supply system 1. When determining the operation mode, for example, the power demand (power consumption status) of the load 3 may also be taken into consideration. Information related to the power demand of the load 3 may be obtained by the mode control unit 56, for example, from a notification from the load 3. Also, a prediction related to the power demand may be made in advance within the mode control unit 56.

Among these, when the operation mode M12 is selected, in step S44, the rectifier voltage _{VRF is set so that the rectifier voltage VRF is} sufficiently larger (for example, 3 V or more) than the storage battery voltage _VLIB ( _VRF > _VLIB ). The set rectifier voltage _VRF is transmitted as a command from the rectifier voltage command unit 504 to the voltage adjustment unit 57, and the rectifier voltage is adjusted in the voltage adjustment unit 57 (step S16).

Moreover, when the operation mode M14 is selected, in step S45, the rectifier voltage VRF is set so that the rectifier voltage _{VRF is smaller than the storage battery voltage VLIB (VRF < VLIB). The set rectifier voltage VRF is transmitted as a} command from the rectifier voltage command unit 504 to the voltage adjustment unit 57, and the rectifier voltage is adjusted in the voltage adjustment unit 57 (step S16).

Furthermore, when the operation mode M15 is selected, in step S46, the rectifier voltage VRF is set so that the storage battery voltage _VLIB and the rectifier voltage _{VRF have the same value (VRF = VLIB). The set rectifier voltage VRF is transmitted as} a command from the rectifier voltage command unit 504 to the voltage adjustment unit 57, and the rectifier voltage is adjusted in the voltage adjustment unit 57 (step S16).

Furthermore, when the operation mode M13 is selected, in step S47, the rectifier voltage V _{RF is set so that the rectifier voltage V RF} is slightly larger than the storage battery voltage V _LIB (V _RF = V _LIB + ΔV). ΔV at this time is set to, for example, about 0.1 _{V to 2 V. The set rectifier voltage V RF is} transmitted as a command from the rectifier voltage command unit 504 to the voltage adjustment unit 57, and the rectifier voltage is adjusted in the voltage adjustment unit 57 (step S16).

The selection of the operating mode may be repeated. For example, one of steps S44 to S47 may be selected and a command issued to the voltage adjustment unit 57 (step S16). After that, after a predetermined time, the steps of checking the storage battery voltage (step S42) and selecting the mode (step S43) may be repeated again, and the rectifier voltage may be adjusted (step S16).

[Action]
The DC power supply system 1 is connected to an electric vehicle 7 that performs charging and discharging operations of the storage battery based on an external command. In this state, the voltage of the power supplied from the rectifier 2 is adjusted based on an operation mode selected based on the power demand in the load 3, the charging and discharging operations between the electric vehicle 7 and the storage battery 4, and the voltage of the storage battery 4 confirmed by the storage battery voltage confirmation unit 55. As a result, the DC power supply system 1 is controlled so that power is exchanged within the DC power supply system 1 based on the selected operation mode. Since the operation mode is selected based on the voltage of the storage battery 4 while charging and discharging the storage battery for the electric vehicle 7 based on an external command, a stable power supply to the load 3 can be achieved while appropriately managing the amount of electricity stored in the storage battery 4 and the battery for the electric vehicle 7.

As described above, for example, when a stable power supply to the load 3 is required even in a situation where the power supply from the commercial power source 6 is unstable, securing a backup power source such as a storage battery 4 may be considered. Utilizing the storage battery of the electric vehicle 7 as a backup power source may be considered. However, since the electric vehicle 7 is required to be operated in a way that takes advantage of its mobile characteristic, it is also required to secure a certain amount of stored power in the storage battery of the electric vehicle 7.

In the above-mentioned environment, even in a situation where power is supplied from the commercial power source 6, appropriate management of the amount of electricity stored in the storage battery 4 and the electric vehicle 7 is required. However, while the electric vehicle 7 may perform either charging or discharging, no detailed consideration has been given to how to adjust the charging and discharging in the storage battery 4 and the electric vehicle 7 while stably continuing the power supply to the load 3. In contrast, according to the above-mentioned DC power supply system 1, in a state where the battery of the electric vehicle 7 is charged and discharged based on an external command, an operation mode related to the transfer of power can be set based on the voltage of the storage battery 4 as well. Then, in order to execute the operation mode, the output voltage from the rectifier 2 can be adjusted. Therefore, it is possible to stably supply power to the load 3 while appropriately managing the amount of electricity stored in the storage battery 4 and the battery for the electric vehicle 7.

Here, the mode control unit 56 of the DC power supply system 1 may select the operation mode based on the power demand of the load 3, the charge/discharge operation between the electric vehicle 7, and the voltage of the storage battery 4. By selecting the operation mode in the mode control unit 56 based on the power demand of the load 3, the charge/discharge operation between the electric vehicle 7, and the voltage of the storage battery 4, for example, when the power demand or the charge/discharge operation of the electric vehicle 7 is changed, the mode control unit 56 can select the operation mode. Therefore, for example, even when the system administrator is not involved, the operation mode can be appropriately changed, and a stable power supply to the load can be achieved while appropriately managing the amount of electricity stored in the storage battery and the electric vehicle battery.

The mode control unit 56 may select the operation mode when the charge/discharge state between the electric vehicle 7 changes. As described above, when the charge/discharge state of the electric vehicle 7 changes, it becomes necessary to change the flow of power within the DC power supply system 1. In particular, if the operation mode is set to transfer power between the electric vehicle 7, it becomes necessary to change it. Therefore, by reselecting the operation mode when the charge/discharge state changes, the operation mode can be appropriately changed.

When an operating mode in which power from the commercial power source 6 is not supplied to the storage battery 4 is specified, the voltage adjustment unit 57 may be configured to adjust the voltage of the power output from the rectifier 2 so that the voltage value of the power output from the rectifier is slightly higher (ΔV) than the voltage of the storage battery 4. In this case, it is possible to supply the power output from the rectifier 2 to another device without supplying it to the storage battery 4.

In addition, when an operating mode in which power from the commercial power source 6 is not used to supply power to the load 3 is specified, the voltage adjustment unit 57 may adjust the voltage of the power output from the rectifier 2 so that the voltage value of the power output from the rectifier 2 is smaller than the voltage of the storage battery 4. In this case, even when connected to the commercial power source 6, power can be transferred within the DC power supply system 1 without supplying power from the commercial power source 6.

When an operating mode is specified in which power from the commercial power source 6 is used to supply power to the load 3, the voltage adjustment unit 57 may adjust the voltage of the power output from the rectifier 2 so that the voltage value of the power output from the rectifier 2 is sufficiently large (e.g., 3 V or more) relative to the voltage of the storage battery 4. In this case, it becomes possible to supply the power output from the rectifier 2 to the load 3.

When discharging from the electric vehicle 7, the voltage adjustment unit 57 may adjust the voltage of the power output from the rectifier 2 so that it does not exceed the output voltage from the electric vehicle 7. In this case, the power output from the rectifier 2 can be moved within the DC power supply system 1 while maintaining the discharging operation from the electric vehicle 7.

[Modification]
Although the present embodiment has been described in detail above, it is clear to those skilled in the art that the present embodiment is not limited to the embodiment described in this specification. The present embodiment can be implemented as a modified or altered form without departing from the spirit and scope of the present disclosure defined by the description of the claims. Therefore, the description in this specification is intended to be illustrative and does not have any limiting meaning on the present embodiment.

For example, in the above embodiment, the load 3 of the DC power supply system 1 is a communication device, but the load 3 is not limited to a communication device.

In addition, in the above embodiment of the DC power supply system 1, the mode selection is performed by the mode control unit 56. However, the selection of the operation mode itself may be performed by the user of the DC power supply system 1. In other words, the operation mode may be selected manually. In this case, the mode control unit 56 receives the operation mode designation by, for example, presenting the information acquired by the EV operation information acquisition unit 501 and the storage battery voltage information acquisition unit 502 to the user. Then, based on the designated operation mode, the rectifier voltage command unit 504 instructs the voltage adjustment unit 57 to adjust the output voltage from the rectifier 2. With this configuration, for example, it is possible for the user to forcibly change the operation mode in consideration of the operating status of the DC power supply system 1. Also, the manual (user) designation of the operation mode and the determination (selection) of the operation mode by the operation mode determination unit 503 may be combined to change which one to use depending on the situation.

For example, the mode control unit 56 may be configured to end the operation by a timeout after a predetermined time has elapsed. The operation may also be ended using a timer or manually.

In addition, in the DC power supply system 1 of the above embodiment, the control unit 52 including the mode control unit 56 is provided in the converter device 5, but the control unit 52 may be provided independently of the converter function unit 51.

Furthermore, each part constituting the control unit 52 does not have to be provided inside a single device.

[others]
The block diagrams used in the description of the above embodiments show blocks of functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. In addition, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically combined, or may be realized using two or more devices that are physically or logically separated and directly or indirectly (for example, using wires, wirelessly, etc.) connected to each other and using these multiple devices. The functional block may be realized by combining the one device or the multiple devices with software. In addition, the wording "apparatus" described in this embodiment can be read as a circuit, a device, a unit, etc.

Functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs the transmission function is called a transmitting unit or a transmitter. As mentioned above, there are no particular limitations on the method of realization for each of these.

The processing steps, sequences, flow charts, etc. of each aspect/embodiment described in this disclosure may be reordered unless inconsistent. For example, the methods described in this disclosure present elements of various steps using an example order and are not limited to the particular order presented.

The input and output information may be stored in a specific location (e.g., memory) or may be managed using a management table. The input and output information may be overwritten, updated, or added to. The output information may be deleted. The input information may be transmitted to another device.

The determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a comparison of numerical values (e.g., a comparison with a predetermined value).

Each aspect/embodiment described in this disclosure may be used alone, in combination, or switched depending on the execution. In addition, notification of specific information (e.g., notification that "X is the case") is not limited to being done explicitly, but may be done implicitly (e.g., not notifying the specific information).

Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Software, instructions, information, etc. may also be transmitted and received via a transmission medium. For example, if the software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and/or wireless technologies (such as infrared, microwave), then these wired and/or wireless technologies are included within the definition of a transmission medium.

The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

As used in this disclosure, the terms "system" and "network" are used interchangeably.

As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching in a table, database, or other data structure), ascertaining, and deeming something to be "determined" or "determined." In addition, "judgment" and "decision" may include regarding receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, and accessing (e.g., accessing data in memory) as having been "judged" or "decided". In addition, "judgment" and "decision" may include regarding resolving, selecting, choosing, establishing, comparing, and the like as having been "judged" or "decided". In other words, "judgment" and "decision" may include regarding some action as having been "judged" or "decided". In addition, "judgment" may be interpreted as "assuming", "expecting", "considering", and the like.

The terms "connected", "coupled", or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access". As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using at least one of one or more wires, cables, and printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Additionally, the term "or," as used in this disclosure, is not intended to be an exclusive or.

In this disclosure, where articles have been added through translation, such as a, an, and the in English, this disclosure may include that the nouns following these articles are in the plural form.

In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combined" may also be interpreted in the same way as "different."

[Additional Notes]
A DC power supply system according to one embodiment of the present disclosure is a system connected to an electric vehicle that charges and discharges a storage battery based on external commands, and controls power supplied to a load that uses DC power. The system includes a rectifier that converts AC power from a commercial power source into DC power, a load that consumes the DC power, a storage battery voltage confirmation unit that confirms the voltage of the storage battery, a voltage adjustment unit that adjusts the voltage of the power output from the rectifier, and a mode control unit that controls each unit based on an operation mode that is a state of power exchange between the commercial power source, the electric vehicle, the storage battery, and the load, which is selected based on the power demand of the load, the charging and discharging operation between the electric vehicle and the storage battery, and the voltage of the storage battery confirmed by the storage battery voltage confirmation unit, and the voltage adjustment unit adjusts the voltage of the power supplied from the rectifier based on the operation mode selected by the mode control unit.

According to the DC power supply system described above, the voltage of the power supplied from the rectifier is adjusted based on the operation mode selected based on the power demand of the load, the charging and discharging operation between the electric vehicle and the storage battery, and the storage battery voltage confirmed by the storage battery voltage confirmation unit. As a result, the power is controlled to be exchanged based on the selected operation mode. Since the operation mode is selected based on the storage battery voltage while charging and discharging the electric vehicle storage battery based on an external command, a stable power supply to the load is possible while appropriately managing the amount of electricity stored in the storage battery and the electric vehicle battery.

The mode control unit may select the operation mode based on the power demand of the load, the charging and discharging operation between the load and the electric vehicle, and the voltage of the storage battery.

The mode control unit selects an operation mode based on the power demand of the load, the charging and discharging operation between the load and the electric vehicle, and the voltage of the storage battery. This allows the mode control unit to select an operation mode when, for example, the power demand or the charging and discharging operation of the electric vehicle changes. Therefore, for example, even when the system administrator is not involved, the operation mode can be appropriately changed, and a stable power supply to the load can be achieved while appropriately managing the amount of power stored in the storage battery and the electric vehicle battery.

The mode control unit may select the operation mode when a change occurs in the charging/discharging state between the electric vehicle and the mode control unit.

When the charging/discharging state between the electric vehicle and the system changes, it becomes necessary to change the flow of power within the DC power supply system. By reselecting the operating mode when the charging/discharging state changes, the operating mode can be appropriately changed, enabling a stable supply of power to the load while appropriately managing the amount of stored power in the storage battery and the electric vehicle battery.

The voltage adjustment unit may be configured to adjust the voltage of the power output from the rectifier so that the voltage value of the power output from the rectifier is slightly higher than the voltage of the storage battery when an operating mode in which power from the commercial power source is not supplied to the storage battery is specified.

The above configuration makes it possible to supply the power output from the rectifier to other devices without feeding it to a storage battery.

The voltage adjustment unit may be configured to adjust the voltage of the power output from the rectifier so that the voltage value of the power output from the rectifier is smaller than the voltage of the storage battery when an operating mode is specified in which power from the commercial power source is not used to supply power to the load.

With the above configuration, even when connected to a commercial power source, power can be transferred within the DC power system without power being supplied from the commercial power source.

The voltage adjustment unit may be configured to adjust the voltage of the power output from the rectifier so that the voltage value of the power output from the rectifier is sufficiently large relative to the voltage of the storage battery when an operating mode is specified in which power from the commercial power source is used to supply power to the load.

The above configuration makes it possible to supply the power output from the rectifier to a load.

The voltage adjustment unit may be configured to adjust the voltage of the power output from the rectifier so that it does not exceed the output voltage from the electric vehicle when discharging from the electric vehicle.

The above configuration allows the power output from the rectifier to be moved within the DC power supply system while maintaining the discharge operation from the electric vehicle.

1...DC power supply system, 2...rectifier, 3...load, 4...storage battery, 5...converter device, 6...commercial power supply, 7...electric vehicle, 51...converter function unit, 52...control unit, 53...charge/discharge switching unit, 54...DC/DC conversion unit, 55...storage battery voltage confirmation unit, 56...mode control unit, 57...voltage adjustment unit, 501...EV operation information acquisition unit, 502...storage battery voltage information acquisition unit, 503...operation mode determination unit, 504...rectifier voltage command unit.

Claims (7)

A system that is connected to an electric vehicle that performs charging and discharging operations of a storage battery based on an external command and controls power supplied to a load that uses DC power,
A rectifier that converts AC power from a commercial power source into DC power;
A load that consumes the DC power;
a battery voltage confirmation unit that confirms the voltage of the battery;
a voltage adjusting unit that adjusts the voltage of the power output from the rectifier;
a mode control unit that controls each unit based on an operation mode that is a state of power exchange between the commercial power source, the electric vehicle, the storage battery, and the load, selected based on a power demand in the load, a charging/discharging operation between the load and the electric vehicle, and a voltage of the storage battery confirmed by the storage battery voltage confirmation unit,
The voltage adjusting unit adjusts the voltage of the power supplied from the rectifier based on the operation mode selected by the mode control unit. The DC power supply system according to claim 1, wherein the mode control unit selects the operation mode based on the power demand in the load, the charging and discharging operation between the load and the electric vehicle, and the voltage of the storage battery. The DC power supply system according to claim 2, wherein the mode control unit selects the operation mode when a change occurs in the state of charging/discharging between the electric vehicle and the mode control unit. The DC power supply system according to any one of claims 1 to 3, wherein the voltage adjustment unit adjusts the voltage of the power output from the rectifier so that the voltage value of the power output from the rectifier is slightly higher than the voltage of the storage battery when an operating mode is specified in which power from the commercial power source is not supplied to the storage battery. The DC power supply system according to any one of claims 1 to 3, wherein the voltage adjustment unit adjusts the voltage of the power output from the rectifier so that the voltage value of the power output from the rectifier is smaller than the voltage of the storage battery when an operating mode is specified in which power from the commercial power supply is not used to supply power to the load. The DC power supply system according to any one of claims 1 to 3, wherein the voltage adjustment unit adjusts the voltage of the power output from the rectifier so that the voltage value of the power output from the rectifier is sufficiently large relative to the voltage of the storage battery when an operating mode is specified in which power from the commercial power supply is used to supply power to the load. The DC power supply system according to any one of claims 1 to 5, wherein the voltage adjustment unit adjusts the voltage of the power output from the rectifier when discharging from the electric vehicle so that the voltage does not exceed the output voltage from the electric vehicle.

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