JP7634647B2 - DC Power System - Google Patents

Description

This disclosure relates to a DC power supply system including an electric vehicle (hereinafter also referred to as "EV"), a storage battery (typically a lithium-ion battery (hereinafter also referred to as "LIB")), and a photovoltaic power generation device. Note that the photovoltaic power generation device will hereinafter also be referred to as "PV", derived from photovoltaic.

In recent years, there has been an increasing demand for communications infrastructure that can maintain an uninterrupted power supply even in the event of a disaster, in order to strengthen disaster resistance. For example, the installation of additional backup power sources at base stations has been implemented. The above backup power sources mainly use lead-acid batteries, but because lead-acid batteries have a low energy density, it can be difficult to install additional batteries due to space constraints at base stations.

Meanwhile, there is a growing expectation that utilizing distributed power sources, including electric vehicles equipped with fuel cells, will improve resilience in the event of a disaster, and in the future, it will become necessary to establish technology to supply power to base stations using electric vehicles as part of disaster prevention measures.

In addition, as the use of natural energy such as solar power generation has been attracting attention, solar power generation devices are increasingly being installed in base stations. Currently, most DC power generated by solar power generation devices is converted to AC by a power conditioner and used. In this case, during a power outage due to a disaster or the like, the power conditioner does not operate, and the DC power generated by the solar power generation device is not supplied to the communication device in the base station. Therefore, from the perspective of securing power sources during disasters, etc., DC power supply systems are attracting attention in order to supply DC power generated by the solar power generation device to the communication device even during a power outage. For example, Patent Document 1 discloses a DC power supply system in which a total of four DC power sources, including a rectifier (also called a system power source) that converts AC power from a commercial power system into DC power, a solar power generation device, a storage battery, and an electric vehicle, are connected to a communication load.

Patent No. 6577076

In a DC power supply system in which the four DC power sources described above are connected to a communication load, it is necessary to ensure that the State Of Charge (hereinafter also referred to as "SOC"), which is an indicator of the charging state of an electric vehicle, is maintained at a certain level or higher, taking into consideration that the electric vehicle will be used (moved) as a vehicle. In addition, it is also necessary to ensure that the SOC of the storage battery is maintained at a certain level or higher in order to provide backup in the event of a power outage in the grid. Furthermore, in order to effectively utilize the surplus power generated by the solar power generation device, a control method is desired that effectively charges the surplus power generated by the storage battery and the electric vehicle with the surplus power generated.

The present disclosure has been made to solve the above problems, and aims to effectively utilize surplus generated power from a solar power generation device while ensuring the charge state required for the movement of an electric vehicle and the charge state of a storage battery required for backup functions.

The DC power supply system of the present disclosure comprises an electric vehicle, a storage battery, a solar power generation device, a rectifier that converts AC current supplied from a commercial power source into DC current and supplies the DC current to a load, and a control device that performs control related to charging and discharging. The control device includes a pattern determination unit that determines a pattern related to charging and discharging from a charging pattern and a discharging pattern based on the presence or absence of surplus power in the solar power generation device and current time information, and an operation mode determination unit that determines one operation mode in the pattern determined by the pattern determination unit based on the result of comparing a charging state index of the electric vehicle with a predetermined reference value and a result of comparing a charging state index of the storage battery with a predetermined reference value, and performs control related to charging and discharging based on the determined operation mode.

In the above DC power supply system, the charging and discharging patterns are determined from the charging and discharging patterns based on the presence or absence of surplus power in the photovoltaic power generation device and current time information. Therefore, for example, the charging and discharging patterns can be appropriately determined depending on whether the current time is daytime when the photovoltaic power generation device can operate and the presence or absence of surplus power in the photovoltaic power generation device. In addition, based on the comparison result of the charge state index of the electric vehicle with a reference value and the comparison result of the charge state index of the storage battery with a reference value, one operation mode in the determined pattern is determined, and control related to charging and discharging is performed based on the determined operation mode. Therefore, by monitoring the charge state of the electric vehicle and the charge state of the storage battery, the charge state necessary for the movement of the electric vehicle and the charge state of the storage battery necessary for the backup function are ensured, while control related to charging and discharging based on an appropriate operation mode is realized, and surplus generated power from the photovoltaic power generation device can be effectively utilized.

According to the present disclosure, it is possible to effectively utilize surplus power generated by a solar power generation device while ensuring the charge state required for the movement of an electric vehicle and the charge state of a storage battery required for backup functions.

FIG. 1 is a configuration diagram of a DC power supply system according to first and second embodiments. FIG. 2 is a configuration diagram of a control device in the first and second embodiments. FIG. 2 is a functional block diagram showing a configuration of a control unit in the first embodiment. 13A is a table showing examples of operation modes in a discharging pattern, and FIG. 13B is a table showing examples of operation modes in charging patterns 1 and 2. FIG. FIG. 4 is a flow chart showing a charge/discharge control process in the first embodiment. FIG. 11 is a flow chart showing a process of determining an operation mode of a discharge pattern. FIG. 11 is a flowchart showing an operation mode determination process for a charging pattern 1. FIG. 11 is a functional block diagram showing a configuration of a control unit in a second embodiment. FIG. 11 is a flowchart showing a charge/discharge control process in a second embodiment. FIG. 11 is a flowchart showing an operation mode determination process for a charging pattern 2. FIG. 2 is a diagram illustrating an example of a hardware configuration of a control device.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. The following describes a first embodiment of a basic type of charge/discharge control in a DC power supply system in which a total of four DC power sources, a system power source, a solar power generation device, a storage battery, and an electric vehicle, are connected to a communication load, and a second embodiment that further adds a process for adjusting the charging current to the electric vehicle depending on the situation.

[Overall configuration of DC power supply system]
First, the overall configuration of the DC power supply system according to the first and second embodiments will be described.

As shown in Fig. 1, the DC power supply system 1 includes an electric vehicle 20, a storage battery 40, a solar power generation device 30, a rectifier 50 that converts AC current supplied from a commercial power supply 60 into DC current with a voltage of about 48V and supplies the DC power, and a control device 10 that controls charging and discharging, as described below. This DC power supply system 1 is installed in a base station or the like, and is configured such that a total of four DC power sources, namely, a system power supply (rectifier 50 and commercial power supply 60), a solar power generation device 30, a storage battery 40, and an electric vehicle 20, are connected to a communication load (such as communication equipment in a base station) 70 via the control device 10.

As shown in FIG. 2, the control device 10 includes a control unit 11 that determines the charge/discharge pattern and operating mode described below and controls charging and discharging in the DC power supply system 1, a charge/discharge switching unit 12 that switches between charging and discharging in accordance with the charge/discharge pattern determined by the control unit 11, a voltage sensor 13 that measures the voltage of the bus (hereinafter referred to as "bus voltage") which is the power supply path from the rectifier 50 to the communication load 70, and a charge/discharge unit 14 that performs charging and discharging in accordance with the operating mode determined by the control unit 11.

[First embodiment]
3, the control unit 11 in the first embodiment includes a timer unit 11A, a bus voltage monitoring unit 11B, a pattern determination unit 11C, an operation mode determination unit 11D, a storage battery state monitoring unit 11E, and an EV state monitoring unit 11F. Among these, the timer unit 11A is a functional unit that provides current time information to the pattern determination unit 11C, and the bus voltage monitoring unit 11B is a functional unit that monitors the bus voltage measured and output by the voltage sensor 13 in FIG. 2 and provides the obtained bus voltage information to the pattern determination unit 11C.

The pattern determination unit 11C is a functional unit that determines a charging/discharging pattern from a charging pattern and a discharging pattern based on the presence or absence of surplus power in the photovoltaic power generation device 30 and current time information. The pattern determination unit 11C also determines that there is surplus power in the photovoltaic power generation device 30 when the output voltage of the photovoltaic power generation device 30 exceeds a predetermined surplus power threshold. In practice, the presence or absence of surplus power is determined by utilizing the characteristic that the output voltage of the photovoltaic power generation device 30 becomes equal to the bus voltage when surplus power is generated, and monitoring whether the bus voltage has exceeded the surplus power threshold at which it can be determined that there is surplus power. In this way, the presence or absence of surplus power can be appropriately determined by utilizing the characteristic that the output voltage of the photovoltaic power generation device 30 becomes equal to the bus voltage when surplus power is generated.

In addition, the pattern determination unit 11C defines the time period during which power generation by the solar power generation device 30 is expected (for example, the time period from sunrise to sunset) as "daytime" and the time period other than daytime as "nighttime", and aims to purchase electricity as cheaply as possible during the nighttime while making the most of renewable energy, assuming that electricity rates tend to be higher during daytime than during nighttime. Specifically, when the current time is daytime and it is determined that there is surplus power in the solar power generation device 30, and when the current time is nighttime, the pattern determination unit 11C determines the pattern related to charging and discharging as the charging pattern, and when the current time is daytime and it is determined that there is no surplus power in the solar power generation device 30, the pattern related to charging and discharging is determined as the discharging pattern. With this pattern determination method, it is possible to use electricity as cheaply as possible during the nighttime while making the most of renewable energy, even when using a system power source. Details of the above process will be described later with reference to Figures 5 to 7.

The battery status monitoring unit 11E is a functional unit that monitors the SOC, which is a charging state index indicating the charging state of the storage battery 40, and provides the obtained SOC information of the storage battery 40 to the operation mode determination unit 11D. The EV status monitoring unit 11F is a functional unit that monitors the SOC, which is a charging state index indicating the charging state of the electric vehicle 20, and provides the obtained SOC information of the electric vehicle 20 to the operation mode determination unit 11D.

The operation mode determination unit 11D is a functional unit that compares the SOC (SOC _EV ) of the electric vehicle 20 with a predetermined reference value and the SOC (SOC _LIB ) of the storage battery 40 with a predetermined reference value, and determines one operation mode in the pattern determined by the pattern determination unit 11C based on the comparison results. Although details will be described later using Figures 6 and 7, a plurality of reference values are used as the above-mentioned predetermined reference value, and for example, for the SOC _EV , it is compared with SOC _lim which is a predetermined lower limit value, SOC _low which is a warning value set higher than this lower limit value, and 100% (or a predetermined value close to 100%) for determining whether or not it is fully charged. The "alert value SOC _low " here is a threshold value for determining that a drop in the SOC _EV of the electric vehicle 20 should be alerted, and in the process of FIG. 6 described later, when it is determined that the SOC _EV of the electric vehicle 20 has become equal to or lower than the alert value SOC _low , a control is performed to relatively suppress the power supply from the electric vehicle 20 by further adding a storage battery 40 to the electric vehicle 20 and the solar power generation device 30 as a power supply source to the communication load 70 (switching from operation mode 1 to 2 described later). The SOC _LIB is compared with a predetermined lower limit SOC _LIBlim and 100% (or a predetermined value close to 100%) for determining whether or not the battery is fully charged. The operation mode determination unit 11D also performs control related to charging and discharging based on the determined operation mode by sending control signals to the charge/discharge switching unit 12 and the charge/discharge unit 14 in FIG. 2.

Here, various operation modes in the discharge pattern will be outlined using FIG. 4(a). In the discharge pattern, "operation mode 1" is an operation mode in which power from the electric vehicle 20 and the solar power generation device 30 is supplied to the communication load 70, and "operation mode 2" is an operation mode in which power from the electric vehicle 20, the storage battery 40, and the solar power generation device 30 is supplied to the communication load 70. In addition, "operation mode 3" is an operation mode in which power from the storage battery 40 and the solar power generation device 30 is supplied to the communication load 70, and "operation mode 0" is an operation mode in which power is supplied to the communication load 70 only from the system power source (rectifier 50 and commercial power source 60).

Next, various operation modes in the charging pattern will be outlined using FIG. 4(b). In the charging pattern, "operation mode 4" is an operation mode in which power from the rectifier 50 or the solar power generation device 30 is supplied to the electric vehicle 20, the storage battery 40, and the communication load 70, and "operation mode 5" is an operation mode in which power from the rectifier 50 or the solar power generation device 30 is supplied to the electric vehicle 20 and the communication load 70. In addition, "operation mode 6" is an operation mode in which power from the rectifier 50 or the solar power generation device 30 is supplied to the storage battery 40 and the communication load 70, and "operation mode 7" is an operation mode in which power from the rectifier 50 or the solar power generation device 30 is supplied only to the communication load 70. In addition, in the above operation modes 4 to 7, power from the "solar power generation device 30" is supplied when surplus power is generated in the solar power generation device 30, and power from the "rectifier 50" is supplied at other times.

[Charge/Discharge Control Process in the First Embodiment]
The charge/discharge control process executed by the control unit 11 will be described with reference to Fig. 5 to Fig. 7. The pattern determination unit 11C basically determines the charge/discharge pattern to be the discharge pattern if the current time is the "daytime", and determines the charge/discharge pattern to be the charge pattern 1 if the current time is the "nighttime". However, if surplus power is generated in the photovoltaic power generation device 30 even during the "daytime", the discharge pattern is switched to the charge pattern in order to effectively utilize renewable energy. Note that the process of Fig. 5 is repeatedly executed at, for example, a predetermined time interval. Therefore, the charge/discharge pattern is switched depending on the current time and whether or not there is surplus power in the photovoltaic power generation device 30, and the operation mode is also switched in accordance with the fluctuations in the SOC (SOC _EV ) of the electric vehicle 20 and the SOC (SOC _LIB ) of the storage battery 40.

Specifically, as shown in Fig. 5, if the current time is "daytime" (YES in step S1), the pattern determination unit 11C causes the operation mode determination unit 11D to execute the operation mode determination process of Fig. 6 (step S2). In the process of Fig. 6, if the SOC _EV of the electric vehicle 20 is above an alert value SOC _low set higher than a predetermined lower limit value SOC _lim (YES in step S21), the operation mode 1 (operation mode in which power from the electric vehicle 20 and the solar power generation device 30 is supplied to the communication load 70) is determined (step S22), and an operation of supplying power from the electric vehicle 20 and the solar power generation device 30 to the communication load 70 based on the operation mode is executed. Thereafter, the process of step S2 in Fig. 5 is repeatedly executed unless surplus power is generated in the solar power generation device 30 or the current time is not "nighttime".

In step S2 (the processing in FIG. 6 ), when the SOC _EV of the electric vehicle 20 becomes equal to or lower than the alert value SOC _low (NO in step S21) but is above the lower limit value SOC _lim (YES in step S23), the operation mode 2 (an operation mode in which power from the storage battery 40, the electric vehicle 20, and the solar power generation device 30 is supplied to the communication load 70) is determined (step S24), and an operation of supplying power from the storage battery 40, the electric vehicle 20, and the solar power generation device 30 to the communication load 70 is executed based on this operation mode.

Thereafter, when the SOC _EV of the electric vehicle 20 decreases and becomes equal to or lower than the lower limit value SOC _lim (NO in step S23), discharging from the electric vehicle 20 is stopped and the electric vehicle 20 is placed in a standby state. While the SOC _LIB of the storage battery 40 is above the lower limit value SOC _LIBlim (YES in step S25), the operation mode 3 (an operation mode in which power from the storage battery 40 and the solar power generation device 30 is supplied to the communication load 70) is determined (step S26), and an operation of supplying power from the storage battery 40 and the solar power generation device 30 to the communication load 70 is executed based on the operation mode. Furthermore, when the SOC _LIB of the storage battery 40 decreases and becomes equal to or lower than the lower limit SOC _LIBlim (NO in step S25), discharging from the storage battery 40 is stopped, and the operation mode 0 (an operation mode in which power from the rectifier 50 is supplied to the communication load 70) is determined (step S27), and an operation of supplying power from the rectifier 50 to the communication load 70 based on the operation mode is executed. By the process in Fig. 6 like this, an appropriate operation mode can be determined for the operation mode of the discharge pattern according to the latest values of the SOC _EV of the electric vehicle 20 and the SOC _LIB of the storage battery 40.

On the other hand, if, during the loop of steps S1 to S3 in FIG. 5, it is determined that surplus power has been generated in the solar power generation device 30 because the bus voltage has exceeded the surplus power threshold (YES in step S3), an operating mode determination process for charging pattern 1 (FIG. 7) is executed in step S4 to switch from the discharging pattern to the charging pattern in order to make effective use of renewable energy.

In step S4 (the process in FIG. 7 ), the operation mode determination unit 11D determines whether the storage battery 40 is fully charged based on whether the SOC _LIB of the storage battery 40 has reached 100% (or a predetermined value close to 100%) (step S41), and determines whether the electric vehicle 20 is fully charged based on whether the SOC _EV of the electric vehicle 20 has reached 100% (or a predetermined value close to 100%) (steps S42, S45).

Here, if neither the storage battery 40 nor the electric vehicle 20 is fully charged (NO in step S41 and NO in S45), operation mode 4 (an operation mode in which power from the rectifier 50 or the solar power generation device 30 is supplied to the electric vehicle 20, the storage battery 40, and the communication load 70) is determined (step S47), and based on this operation mode, an operation is executed to supply power from the rectifier 50 or the solar power generation device 30 to the electric vehicle 20, the storage battery 40, and the communication load 70.

In addition, if the storage battery 40 is not fully charged but the electric vehicle 20 is fully charged (NO in step S41 and YES in S45), there is no need to charge the electric vehicle 20, so operation mode 6 (an operation mode in which power from the rectifier 50 or the solar power generation device 30 is supplied to the storage battery 40 and the communication load 70) is determined (step S46), and an operation is executed to supply power from the rectifier 50 or the solar power generation device 30 to the storage battery 40 and the communication load 70 based on this operation mode.

In addition, if the storage battery 40 is fully charged but the electric vehicle 20 is not fully charged (YES in step S41 and NO in S42), there is no need to charge the storage battery 40, so operation mode 5 (an operation mode in which power from the rectifier 50 or the solar power generation device 30 is supplied to the electric vehicle 20 and the communication load 70) is determined (step S44), and an operation is executed to supply power from the rectifier 50 or the solar power generation device 30 to the electric vehicle 20 and the communication load 70 based on that operation mode.

Furthermore, when both the storage battery 40 and the electric vehicle 20 are fully charged (YES in step S41 and YES in S42), charging the storage battery 40 and the electric vehicle 20 is not necessary, so operation mode 7 (operation mode in which power from the rectifier 50 or the solar power generation device 30 is supplied only to the communication load 70) is determined (step S43), and based on the operation mode, an operation is executed in which power from the rectifier 50 or the solar power generation device 30 is supplied only to the communication load 70. By the process of FIG. 7, an appropriate operation mode can be determined for the operation mode of the charging pattern depending on whether the storage battery 40 is fully charged or not and whether the electric vehicle 20 is fully charged or not.

According to the first embodiment described above, the charging and discharging pattern is appropriately determined depending on whether the current time is daytime or not and whether there is surplus power in the solar power generation device 30, and the SOC of the electric vehicle 20 and the storage battery 40 are monitored to appropriately determine the operation mode. Therefore, while ensuring the charge state required for the movement of the electric vehicle 20 and the charge state of the storage battery 40 required for the backup function, control related to charging and discharging based on an appropriate operation mode is realized, and the surplus generated power of the solar power generation device 30 is distributed to the storage battery 40 and the electric vehicle 20 for charging, thereby making the most of renewable energy and realizing a stable supply of power to the communication load 70 (for example, communication equipment in a base station, etc.), thereby contributing to improving the disaster resistance of the base station. In addition, it is possible to achieve cost reduction by reducing the discharge circuit through discharge control based on DC voltage control.

[Second embodiment]
Next, as a second embodiment, an embodiment in which a process for adjusting the charging current to the electric vehicle depending on the situation is further added will be described.

As shown in FIG. 8, the control unit 11 in the second embodiment is similar to the control unit 11 in the first embodiment (FIG. 3) in that it includes a timer unit 11A, a bus voltage monitoring unit 11B, a pattern determination unit 11C, an operation mode determination unit 11D, a battery status monitoring unit 11E, and an EV status monitoring unit 11F, but differs from the first embodiment in that the operation mode determination unit 11D includes a charging current adjustment unit 11H and a charging control unit 11G described below.

The charging current adjustment unit 11H is a functional unit that adjusts the charging current to the electric vehicle 20 by increasing the charging current to the electric vehicle 20 when the bus voltage (corresponding to the output voltage of the photovoltaic power generation device 30) is not below a predetermined threshold _Vthresh and decreasing the charging current to the electric vehicle 20 when the bus voltage is below the threshold _Vthresh when the photovoltaic power generation device 30 generates surplus power and by doing so adjusts the charging current to the electric vehicle 20. Note that the threshold _Vthresh is set higher than the surplus power threshold for determining whether or not there is surplus power in the photovoltaic power generation device 30, and is set to about 54 V when the system power supply (rectifier 50 and commercial power supply 60) is 48 V DC.

The charging control unit 11G is a functional unit that controls the charging current adjusted by the charging current adjustment unit 11H to charge the surplus power of the solar power generation device 30 to the electric vehicle 20.

As shown in FIG. 9, the second embodiment differs from the first embodiment in that, when surplus power is generated in the solar power generation device 30 (YES in step S3) during operation in the discharge pattern operation mode (i.e., during the loop of steps S1 to S3 in FIG. 9), the process proceeds to step S5, and an operation mode determination process (FIG. 10) for charging pattern 2, which is different from charging pattern 1, is executed. The operation mode determination process for charging pattern 2, which is related to this difference, is described below.

In step S5 (the process in FIG. 10 ), the operation mode determination unit 11D determines whether the storage battery 40 is fully charged based on whether the SOC _LIB of the storage battery 40 has reached 100% (or a predetermined value close to 100%) (step S51), and determines whether the electric vehicle 20 is fully charged based on whether the SOC _EV of the electric vehicle 20 has reached 100% (or a predetermined value close to 100%) (steps S52, S55).

Here, in the cases where (1) the storage battery 40 is not fully charged but the electric vehicle 20 is fully charged (NO in step S51 and YES in S55), (2) the storage battery 40 is fully charged but the electric vehicle 20 is not fully charged (YES in step S51 and NO in S52), and (3) both the storage battery 40 and the electric vehicle 20 are fully charged (YES in step S51 and YES in S52), as in the first embodiment, the operating modes 6, 5, and 7 are determined, respectively (steps S56, S54, and S53), and an operation is executed to supply power from the rectifier 50 or the solar power generation device 30 to the electric vehicle 20, the storage battery 40, and the communication load 70 based on the respective operating modes.

On the other hand, (4) when neither the storage battery 40 nor the electric vehicle 20 is fully charged (NO in step S51 and NO in step S55), the charging current adjustment unit 11H performs the following charging amount _adjustment to increase or decrease the amount of charging to the electric vehicle 20 by a small amount, depending on the result of the determination as to whether the bus voltage V has fallen below a predetermined threshold value Vthresh.

Specifically, if the bus voltage V is not below the threshold _Vthresh (NO in step S57), the charging current adjustment unit 11H increases the charging amount _IEV to the electric vehicle 20 by the minute amount dl (step S60). Here, if the charging amount _IEV to the electric vehicle 20 is set to a predetermined initial value _I0 (e.g., 1 A) and the minute amount dl is set to, for example, 1 A, the charging current adjustment unit 11H adjusts the charging amount _IEV to ( _I0 +dl), that is, 2 A. Thereafter, if the situation is similar, the charging amount _IEV is further increased by the minute amount dl. Also, in step S60, the operation mode is determined to be operation mode 4 (an operation mode in which power from the rectifier 50 or the solar power generation device 30 is supplied to the electric vehicle 20, the storage battery 40, and the communication load 70), and the charging control unit 11G executes an operation of supplying power from the rectifier 50 or the solar power generation device 30 to the electric vehicle 20, the storage battery 40, and the communication load 70 based on the operation mode.

Thereafter, when the bus voltage V falls below the threshold _Vthresh (YES in step S57), after confirming that the charge amount _IEV is not 0 (NO in step S58), the sign of the minute amount dl is reversed (negative) to switch the adjustment of the charge amount _IEV of the electric vehicle 20 from "increase" to "decrease" (step S59). Then, in step S60, the minute amount dl, which is a negative value, is added to the charge amount _IEV of the electric vehicle 20, thereby decreasing the charge amount _IEV by the absolute value of the minute amount dl, and the operation mode is set to operation mode 4, and an operation is executed in which power from the rectifier 50 or the solar power generation device 30 is supplied to the electric vehicle 20, the storage battery 40, and the communication load 70 based on the operation mode. For example, when the bus voltage V falls below the threshold _Vthresh in a state in which the charge amount _IEV is set to 3A, the charge amount _IEV is decreased by 1A and adjusted to 2A.

In this way, when the processing of "I _EV = I _EV + dl" in step S60 is executed after a NO determination in step S57, it is a processing to increase the charge amount I _EV , whereas when the processing is executed after a NO determination in step S58, it is a processing to decrease the charge amount I _EV .

Furthermore, if the bus voltage V is below the threshold value V _thresh (YES in step S57) and it is confirmed that the charge amount I _EV has become 0 (YES in step S58), then there is no charging to the electric vehicle 20, so the operation mode is determined to be operation mode 6 (an operation mode in which power from the rectifier 50 or the solar power generation device 30 is supplied to the storage battery 40 and the communication load 70) (step S61), and based on this operation mode, an operation is executed to supply power from the rectifier 50 or the solar power generation device 30 to the storage battery 40 and the communication load 70.

As in the second embodiment described above, when surplus power is generated in the photovoltaic power generation device 30 and neither the storage battery 40 nor the electric vehicle 20 is fully charged, the charge amount _IEV to the electric vehicle 20 is increased when the bus voltage V, which is equal to the output voltage of the photovoltaic power generation device 30, is not below the threshold _Vthresh , and the charge amount _IEV to the electric vehicle 20 is decreased when the bus voltage V is below the threshold _Vthresh , thereby making it possible to charge the electric vehicle 20 with the maximum charge amount without preventing the charging of the storage battery 40, within a range in which the bus voltage does not become unstable, and within a range in which extra commercial electricity is not purchased. Note that it is assumed that charging of the storage battery 40 is performed by the potential difference between the output voltage of the photovoltaic power generation device 30 and the storage battery 40, and a charging circuit is not required.

[Modifications]
In the DC power supply systems of the first and second embodiments described above, the communication load 70 in Fig. 1 is not limited to a communication device, and may be other devices that consume power. In the DC power supply systems of the first and second embodiments, the control device 10 is configured to have an EV converter function, but the EV converter may be provided independently outside the control device 10. In addition, the voltage sensor 13 is configured to be provided inside the control device 10, but may be provided outside the control device 10.

Note that the block diagrams used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, 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 coupled, or may be realized using two or more devices that are physically or logically separated and directly or indirectly connected (e.g., using wires, wirelessly, etc.) and these multiple devices. The functional blocks may be realized by combining the one device or the multiple devices with software.

Functions include, but are not limited to, judgement, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, election, establishment, comparison, assumption, expectation, regard, 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 either of these.

For example, the control unit in one embodiment of the present disclosure may function as a computer that performs the processing in this embodiment. FIG. 11 is a diagram showing an example hardware configuration of a control device 10 according to one embodiment of the present disclosure. The above-mentioned control device 10 may be physically configured as a computer device including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

In the following description, the term "apparatus" may be interpreted as a circuit, device, unit, etc. The hardware configuration of the control device 10 may be configured to include one or more of the devices shown in the figure, or may be configured to exclude some of the devices.

Each function in the control device 10 is realized by loading a specific software (program) onto hardware such as the processor 1001 and memory 1002, causing the processor 1001 to perform calculations, control communication via the communication device 1004, and control at least one of the reading and writing of data in the memory 1002 and storage 1003.

The processor 1001, for example, operates an operating system to control the entire computer. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc.

The processor 1001 also reads out programs (program codes), software modules, data, etc. from at least one of the storage 1003 and the communication device 1004 into the memory 1002, and executes various processes according to these. The programs used are those that cause a computer to execute at least a portion of the operations described in the above-mentioned embodiments. Although the above-mentioned various processes have been described as being executed by one processor 1001, they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may be transmitted from a network via a telecommunications line.

The memory 1002 is a computer-readable recording medium and may be composed of at least one of, for example, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), a RAM (Random Access Memory), etc. The memory 1002 may be called a register, a cache, a main memory (primary storage device), etc. The memory 1002 can store a program (program code), software module, etc. that can be executed to implement a wireless communication method according to one embodiment of the present disclosure.

Storage 1003 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 1003 may also 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 at least one of memory 1002 and storage 1003.

The communication device 1004 is hardware (transmitting/receiving device) for communicating between computers via at least one of a wired network and a 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 1005 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 1006 is an output device (e.g., a display, a speaker, an LED lamp, etc.) that performs output to the outside. The input device 1005 and the output device 1006 may be integrated (e.g., a touch panel). In addition, each device such as the processor 1001 and the memory 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

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).

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

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

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 used in this disclosure, the terms "include," "including," and variations thereof 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 by 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." In addition, the term may 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."

1...DC power supply system, 10...control device, 11...control unit, 11A...timer unit, 11B...bus voltage monitoring unit, 11C...pattern determination unit, 11D...operation mode determination unit, 11E...battery status monitoring unit, 11F...EV status monitoring unit, 11G...charging control unit, 11H...charging current adjustment unit, 12...charging/discharging switching unit, 13...voltage sensor, 14...charging/discharging unit, 20...electric vehicle, 30...photovoltaic power generation device, 40...battery, 50...rectifier, 60...commercial power supply, 70...communication load (load), 1001...processor, 1002...memory, 1003...storage, 1004...communication device, 1005...input device, 1006...output device, 1007...bus.

Claims (7)

Electric cars and
A storage battery,
A solar power generation device;
A rectifier that converts AC current supplied from a commercial power source into DC current and supplies DC power to a load;
A control device that performs control related to charging and discharging;
Equipped with
The control device includes:
a pattern determination unit that determines a pattern related to charging and discharging from a charging pattern and a discharging pattern based on the presence or absence of surplus power in the solar power generation device and current time information;
an operation mode determination unit that determines one operation mode in the pattern determined by the pattern determination unit based on a result of comparing a charge state indicator of the electric vehicle with a predetermined reference value and a result of comparing a charge state indicator of the storage battery with a predetermined reference value, and performs control related to charging and discharging based on the determined operation mode;
Including,
DC power system. The pattern determination unit is
determining that there is surplus power in the solar power generation device when an output voltage of the solar power generation device exceeds a predetermined surplus power threshold;
2. The DC power supply system according to claim 1. The pattern determination unit is
determining a pattern related to charging and discharging as the charging pattern when the current time is a daytime time during which power generation in the solar power generation device is expected and it is determined that there is surplus power in the solar power generation device, and when the current time is a nighttime time other than the daytime time;
determining, when the current time is a daytime time during which power generation in the solar power generation device is expected and it is determined that there is no surplus power in the solar power generation device, that the pattern related to charging and discharging is the discharging pattern;
3. The DC power supply system according to claim 1 or 2. The operation mode determination unit is
When the determined pattern is a discharge pattern, determining one operation mode from a plurality of operation modes including an operation mode in which power from at least one of the electric vehicle and the storage battery and the solar power generation device is supplied to the load, and an operation mode in which power from the rectifier is supplied to the load;
When the determined pattern is a charging pattern, one operation mode is determined from a plurality of operation modes including an operation mode in which the power from the rectifier or the solar power generation device is supplied to at least one of the electric vehicle and the storage battery and the load, and an operation mode in which the power is supplied only to the load;
A DC power supply system according to any one of claims 1 to 3. The operation mode determination unit determines an operation mode in the discharge pattern as follows:
when the charge state index of the electric vehicle exceeds an alert value which is a threshold value for determining that a decrease in the charge state index of the electric vehicle should be alerted, the alert value being set higher than a predetermined lower limit value, determining an operation mode 1 in which power is supplied from the electric vehicle and the solar power generation device to the load;
when the charge state index of the electric vehicle is equal to or less than the alert value and exceeds the lower limit value, determining an operation mode 2 in which power is supplied from the electric vehicle, the storage battery, and the solar power generation device to the load;
when the charge state index of the electric vehicle is equal to or lower than the lower limit and the charge state index of the storage battery is higher than a predetermined lower limit of the charge state index of the storage battery, determining an operation mode 3 in which power from the storage battery and the solar power generation device is supplied to the load;
determining an operation mode 0 in which power from the rectifier is supplied to the load when the charge state indicator of the storage battery is equal to or less than the storage battery lower limit;
5. The DC power supply system according to claim 4. The operation mode determination unit determines an operation mode in the charging pattern.
determining an operation mode 4 in which power from the rectifier or the solar power generation device is supplied to the electric vehicle, the storage battery, and the load when the charge state indicator of the storage battery does not indicate a full charge and when the charge state indicator of the electric vehicle does not indicate a full charge;
determining an operation mode 5 in which power from the rectifier or the solar power generation device is supplied to the electric vehicle and the load when the charge state indicator of the storage battery indicates a full charge and the charge state indicator of the electric vehicle does not indicate a full charge;
determining an operation mode 6 in which power from the rectifier or the photovoltaic power generation device is supplied to the storage battery and the load when the charge state indicator of the storage battery does not indicate a full charge and the charge state indicator of the electric vehicle indicates a full charge;
When the charge state indicator of the storage battery indicates a full charge and the charge state indicator of the electric vehicle indicates a full charge, determining an operation mode 7 in which power from the rectifier or the solar power generation device is supplied to the load;
6. A DC power supply system according to claim 4 or 5. The operation mode determination unit is
a charging current adjustment unit that adjusts the charging current to the electric vehicle by increasing the charging current to the electric vehicle when the output voltage of the solar power generation device is not below a threshold voltage set higher than a predetermined surplus power threshold, and by reducing the charging current to the electric vehicle when the output voltage of the solar power generation device is below the threshold voltage, when the charging state index of the storage battery does not indicate full charge and the charging state index of the electric vehicle does not indicate full charge;
a charging control unit that controls the charging current adjusted by the charging current adjustment unit so that surplus power from the solar power generation device is charged to the electric vehicle;
Including,
A DC power supply system according to any one of claims 1 to 6.

Images