JP7811486B2 - power management device - Google Patents

Description

The present invention relates to a power management device that manages power while utilizing both vehicle-mounted storage batteries and residential storage batteries that store power supplied from a grid power source or a renewable energy source.

In recent years, there has been an increase in V2H-compatible power conversion devices, which allow users to utilize onboard storage batteries in electric vehicles and residential storage batteries in times of disaster. In addition, there has also been an increase in the use of renewable energy sources such as solar cells, in addition to grid power sources, as power sources for storage batteries.

A known example of the above-mentioned conventional device is a power conversion device that utilizes both a stationary (residential) storage battery and an onboard storage battery, while ensuring the stored power of the onboard storage battery is sufficient for driving (see, for example, Patent Document 1). This device uses a power index value based on the magnitude of grid power to start and stop discharging from the stationary storage battery and charging to the onboard storage battery based on four thresholds: discharge start threshold, discharge end threshold, charge start threshold, and charge end threshold.

Japanese Patent Application Laid-Open No. 2017-189012

However, while conventional devices increase the chances of charging the onboard battery using four thresholds based on the changing power index value of the grid power, and thus increase the likelihood that the onboard battery will have sufficient stored power in the event of sudden use, this is not necessarily reliable. Furthermore, it is necessary to set four thresholds to start and end discharging and charging, making the configuration complex.

Furthermore, the above power index value is based on the magnitude of grid power and does not take into account the power of renewable energy sources. Therefore, if renewable energy sources are primarily used, it is anticipated that the trends in the power index value will be complex, making it difficult to apply. Furthermore, if stationary storage batteries and on-board storage batteries, which have different uses, are charged and discharged using the same standard using the grid power power index value, it may not be possible to ensure a sufficient charge for the on-board storage battery.

The objective of the present invention is to provide a power management device that uses both an on-board storage battery and a residential storage battery, and that can easily and reliably ensure the charge level of the on-board storage battery with a simple configuration.

To achieve the above objective, the power management device of the present invention comprises an on-board storage battery, at least one residential storage battery, a grid power source or a renewable energy power source, an energy distributor that connects the grid power source or the renewable energy power source to the on-board storage battery and the residential storage battery and distributes and supplies power to the on-board storage battery or the residential storage battery, and a controller that controls the energy distributor and controls the amount of power stored in the on-board storage battery and the residential storage battery based on a predetermined threshold value set in advance regarding the amount of power stored in the on-board storage battery.

With this configuration, the amount of electricity stored in the vehicle storage battery and the amount of electricity stored in the residential storage battery are controlled based solely on the predetermined threshold value related to the amount of electricity stored, making it possible to easily and reliably ensure the amount of charge in the vehicle storage battery with a simple configuration.

Preferably, the controller prioritizes charging of the onboard storage battery when the charging rate, which is the level of the amount of electricity stored in the onboard storage battery relative to a preset battery capacity, is equal to or lower than a charging rate threshold, which is one of the predetermined thresholds, and charges the residential storage battery when the charging rate of the onboard storage battery is higher than the charging rate threshold. Therefore, by prioritizing charging of the onboard storage battery based on the charging rate threshold of the onboard storage battery, it is possible to more easily and reliably ensure the amount of charge in the onboard storage battery with a simple configuration.

Preferably, the vehicle storage battery or the residential storage battery is selected as the storage battery to be charged, and the maximum charge amount of the grid power source or renewable energy power source is allocated to the selected storage battery, and the charge amount equal to the difference between the maximum charge amount and the maximum charge amount of the selected storage battery is allocated to the unselected storage battery. In this case, allocation to the vehicle storage battery and the residential storage battery can be performed accurately depending on the selected storage battery to be charged.

Preferably, the energy distributor and the controller are installed within a power conditioner that converts the power from the grid power supply or the renewable energy power supply. In this case, the device configuration can be simplified and made smaller.

In this invention, the amount of electricity stored in the vehicle storage battery and the amount of electricity stored in the residential storage battery are controlled based on a predetermined threshold value related to the amount of electricity stored in the vehicle storage battery that is set in advance. Furthermore, for example, when the charge rate of the vehicle storage battery is equal to or lower than the charge rate threshold value, charging of the vehicle storage battery is prioritized, and when the charge rate of the vehicle storage battery is higher than the charge rate threshold value, charging of the residential storage battery is performed. This makes it possible to easily and reliably ensure the amount of electricity stored in the vehicle storage battery with a simple configuration.

1 is a block diagram illustrating a power management apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a controller in the device. FIG. 1 is a diagram specifically illustrating the device. 1A to 1C are schematic diagrams showing the operation of the device. 1A and 1B are diagrams illustrating the operation of the device. 3 is a flowchart showing the operation of the present device. 3 is a flowchart showing the operation of the present device.

Embodiments of the present invention will now be described with reference to the drawings. Figure 1 is a block diagram showing a power management device 1 according to one embodiment of the present invention. This power management device 1 includes an onboard storage battery 2, a residential (stationary) storage battery 3, a grid power supply 4, a renewable energy power supply 5 such as a solar cell (PV), an energy distributor 6 that connects the grid power supply 4, the solar cell (PV) 5, the onboard storage battery 2, and the residential storage battery 3 and distributes and supplies power to the onboard storage battery 2 or the residential storage battery 3, and a controller 7 that controls the energy distributor 6 and controls the amount of power stored in the onboard storage battery 2 and the residential storage battery 3 based on a preset threshold value related to the amount of power stored in the onboard storage battery 2. The energy distributor 6 and controller 7 are installed in a power conditioner 8 that converts power from the grid power supply 4 and the renewable energy power supply 5.

The energy distributor 6 includes a bidirectional DC/AC converter (inverter) 10, a DC/DC converter 11, and two DC/DC converters 12 and 13. For example, a single-phase three-wire system power supply 4 is connected to the bidirectional DC/AC converter 10, and a solar cell (PV) 5 is connected to the DC/DC converter 11. The outputs of the bidirectional DC/AC converter 10 and the DC/DC converter 11 are connected to the vehicle storage battery 2 via the first bidirectional DC/DC converter 12 and to the residential (stationary) storage battery 3 via the second bidirectional DC/DC converter 13, respectively. Each of the converters 10, 11, 12, and 13 is connected to the controller 7.

Another example of Figure 1 is a configuration in which a DC/DC converter 11 for PV5 and a bidirectional DC/AC converter (inverter) 10 are built into a dedicated V2H stand (not shown), a bidirectional DC/DC converter 12 for the on-board storage battery 2 is provided at the interface between the dedicated V2H stand and the vehicle, the DC/DC converter 11 for PV5, the bidirectional DC/AC converter (inverter) 10, and the bidirectional DC/DC converter 12 for the on-board storage battery 2 are connected at a single point, a connector is connected to the bidirectional DC/DC converter 12 for the on-board storage battery 2, and the connector is connected to the vehicle, with the rest of the configuration being similar to Figure 1.

As shown in FIG. 2, the controller 7 includes a maximum charge (discharge) allocation unit 15 that allocates the maximum charge (discharge) amount to the onboard battery 2 and the fixed battery 3; an onboard battery charge priority selection unit 16 that prioritizes the charging of the onboard battery 2; a charge rate threshold setting unit 17 that sets a threshold for the charge rate, which is the level of the charged power of the onboard battery 2 relative to the battery capacity of the onboard battery 2; a comparison unit 18 that compares the charge rate of the onboard battery 2 detected by the onboard battery charge rate detection unit 21 with the set charge rate threshold; and a charge priority execution unit 19 that prioritizes the charging of the onboard battery 2 or the fixed battery 3. The charge rate of the fixed battery 3 is detected by the fixed battery charge rate detection unit 22.

As shown in Figure 3, the energy distributor 6 allocates charge/discharge power Pc1 and Pd1 to the vehicle storage battery 2 and charge/discharge power Pc2 and Pd2 to the residential storage battery 3 from the total (maximum) charge power Pc and total (maximum) discharge power Pd based on a predetermined charge/discharge power allocation standard. A user interface 9 is connected to the controller 7, which connects to a setting unit 17 where the user sets the vehicle storage battery charging rate threshold.

The comparison unit 12 in Figure 2 compares the preset charging rate threshold for the on-board battery 2 with the detected charging rate of the on-board battery 2, and the charging priority execution unit 13 prioritizes charging of the on-board battery 2 if the charging rate of the on-board battery 2 (SOCv in Figure 3) does not exceed the charging rate threshold (SOCv-set in Figure 3), i.e., if it is less than or equal to the charging rate threshold, and charges the fixed battery 3 if the charging rate of the on-board battery 2 is greater than the charging rate threshold. In Figure 3, the charging rate of the fixed battery 3 is indicated by SOCh.

Figures 4 (A) to (C) show the operation of this device. In Figure 4 (A), when the charge rate of the onboard battery 2 is below the charge rate threshold, charging of the onboard battery 2 is prioritized. P0 indicates the input from the grid power supply 4 or renewable energy power supply 5, and P1 is the maximum charging power of the onboard battery 2.

For example, surplus power from solar cell (PV) 5 is input as input P0 to energy distributor 6. When it is detected that the charging rate of onboard battery 2 is below the charging rate threshold, charging of onboard battery 2 is prioritized and begins at maximum charging power P1. Charging of onboard battery 2 is prioritized as long as the amount of power generated does not exceed the current capacity of onboard battery 2. If the generated power exceeds the current capacity of onboard battery 2 while charging onboard battery 2, the excess is used to charge fixed battery 3, which is charged with charging power P0-P1. If PV5 is generating power while onboard battery 2 is not connected to energy distributor 6, such as while the vehicle is driving, fixed battery 3 is charged.

As shown in Figure 4(B), when it is detected that the charge rate of the on-board battery 2 exceeds the charge rate threshold, charging of the on-board battery 2 is stopped and the fixed battery 3 is charged at input P0. As shown in Figure 4(C), if power is needed while the fixed battery 3 is being charged, discharge occurs only from the fixed battery 3. In this case, the on-board battery 2 is not discharged, and the power of the on-board battery 2 is used only for driving.

In Figures 4 (A) and (B), the vehicle storage battery 2 or fixed storage battery 3 is charged using the input P0 of power supplied from the grid power supply 4 or solar cell (PV) 5. However, when this power is not supplied, i.e., when the input P0 is 0, the charging power of the fixed storage battery 3 or vehicle storage battery 2 may be used.

Figures 5(A) and (B) show states (load-following charging and load-following discharging) in which, for example, a fixed storage battery 3 is charged and discharged while power is supplied to a domestic load 23. In Figure 5(A), load-following charging is performed in which power from, for example, a system power source 4 protected by a CT (current transformer) and another generator 24 is supplied to the domestic load 23 via a selector switch 25, and the power is converted forward by a bidirectional DC/AC converter (inverter) 10 to charge the fixed storage battery 3. In Figure 5(B), load-following discharging is performed in which power from the system power source 4 and generator 24 is converted backward by a bidirectional DC/AC converter (inverter) 19 to discharge the power from the fixed storage battery 3 while being supplied to the domestic load 23 via a selector switch 25.

The lower limit of the remaining charge of the fixed storage battery 3 during load-following charging and discharging is set by the user. For example, when the charging rate SOC value (%) of the fixed storage battery 3 is (use-up level SOCA + 2%) < SOC, load-following charging + surplus charging occurs from the start time of charging to the end time of charging (e.g., 11:00 PM to 7:00 AM), and only surplus charging occurs from the end time of charging to the start time of discharging (e.g., 7:00 AM to 10:00 AM). Here, the use-up level SOCA refers to the level at which stored power is left during normal use of the storage battery. If it falls below (SOCA + 2%) or above, surplus charging occurs, and if it rises from below SOCA, load-following charging + surplus charging occurs.

When SOCA < SOC ≦ (SOCA + 2%), the period from the start of charging to the end of charging will be load following charging + surplus charging, and the period from the end of charging to the start of discharging will be surplus charging or load following charging + surplus charging. When SOC ≦ SOCA, the period from the start of charging to the end of charging and from the end of charging to the start of discharging will both be load following charging + surplus charging. The threshold for load following charging follows a value calculated from the preset contract amperes and margin.

From the discharge start time to the discharge end time (for example, 10:00 to 23:00), if (SOCA + 2%) < SOC, load-following discharge + surplus charging occurs; and if SOCA < SOC ≦ (SOCA + 2%), load-following discharge + surplus charging occurs or surplus charging only. When SOC ≦ SOCA, and from the discharge end time to the charge start time (for example, 23:00), the operation is the same as described above.

This allows the user to easily and appropriately set the lower limit of the remaining capacity of the fixed storage battery 3 during load-following charging and discharging, which charges and discharges the fixed storage battery while supplying power to household loads.

It is also possible to discharge the electricity stored in the vehicle storage battery 3 and supply that electricity to a household load 23.

Figures 6 and 7 are flowcharts showing the operation of the power management device 1. Figure 6 shows the operation of allocating the maximum charge amount to the vehicle storage battery and the residential storage battery according to the selected charging target. Figure 7 shows the operation of prioritizing charging and discharging to the vehicle storage battery and the residential storage battery based on the charging rate threshold of the vehicle storage battery.

First, in FIG. 6, the total (maximum) charge amount (total (maximum) discharge amount) Pchrg-t/Pdschrg-t is calculated based on the device's operating mode and settings (step S1). Next, a determination is made as to whether both the vehicle battery and the residential (stationary) battery should be charged (discharged) (step S2). If both should be charged (discharged), a determination is made as to whether the vehicle battery should be given priority for charging (discharging) (step S3). If both should not be charged (discharged), a determined charge amount (discharge amount) is assigned to each of the vehicle battery and the residential (stationary) battery, taking into account the maximum charge amount (maximum discharge amount) of each battery (step S4), and the process ends.

If the onboard battery is given priority for charging (discharging) in step S3, it is determined whether the total (maximum) charge amount (total (maximum) discharge amount) is greater than the maximum power of the onboard battery (step S5). If it is greater, the maximum charge amount (maximum discharge amount) is allocated to the onboard battery. The charge amount equal to the difference between the maximum charge amount (maximum discharge amount) and the maximum charge amount (maximum discharge amount) of the onboard battery is allocated to the residential (stationary) battery (step S6), and the process ends. If it is not greater, the maximum charge amount (maximum discharge amount) is allocated to the onboard battery, but not to the residential (stationary) battery (step S7), and the process ends.

If the priority for charging (discharging) is not given to the on-board battery in step S3, it is determined whether the total (maximum) charge amount (total (maximum) discharge amount) is greater than the maximum power of the residential (stationary) battery (step S8). If it is greater, the maximum charge amount (maximum discharge amount) is allocated to the on-board battery. The charge amount equal to the difference between the maximum charge amount (maximum discharge amount) and the maximum charge amount (maximum discharge amount) of the on-board battery is allocated to the residential (stationary) battery (step S9), and the process ends. If it is not greater, the maximum charge amount (maximum discharge amount) is allocated to the residential (stationary) battery, not to the on-board battery (step S10), and the process ends.

This allows for accurate allocation to vehicle batteries and residential (stationary) batteries depending on the selected storage battery to be charged.

In Figure 7, it is determined whether the state of charge (SOC) of the onboard battery (SOCv) is smaller than (or equal to) the state of charge threshold SOCv-set for the onboard battery (step S21). If it is smaller (or equal), the onboard battery is given priority during charging, and the residential (stationary) battery is given priority during discharging (step S22), and the process ends. If it is larger, the residential (stationary) battery is given priority during charging, and the onboard battery is given priority during discharging (step S23), and the process ends.

As a result, based on the charging rate threshold of the onboard storage battery, the onboard storage battery is given priority when charging, and the residential (fixed) storage battery is given priority when discharging, so that the charge amount of the onboard storage battery can be easily and reliably ensured with a simple configuration.

Thus, the present invention includes an on-board battery charging priority selection unit 16 that prioritizes charging of the on-board battery 2, an on-board battery 2 charging rate threshold setting unit 17, a comparison unit 18 that compares the detected on-board battery 2 charging rate with the charging rate threshold, and a charging priority execution unit 19 that prioritizes charging of the on-board battery 2 or the residential (stationary) battery 3. When the on-board battery 2 charging rate is equal to or lower than the on-board battery charging rate threshold, charging of the on-board battery 2 is prioritized, and when the on-board battery 2 charging rate is higher than the charging rate threshold, charging of the residential (stationary) battery 3 is performed. Therefore, the amount of charge for the on-board battery 2 can be easily and reliably ensured with a simple configuration.

Here, when managing a group of storage batteries with a fixed storage battery capacity, a threshold for the absolute value of the stored energy amount may be used instead of a charging rate threshold as a threshold for the stored energy amount of the storage batteries.

In the above embodiment, solar cells (PV) are used as an example of a renewable energy power source, but fuel cells (FC), wind power (WP), cogeneration power sources, geothermal power sources, biomass power sources, etc. may also be used.

The present invention is not limited to the above-described embodiments, and various additions, modifications, and deletions are possible without departing from the spirit of the present invention. Therefore, such additions, modifications, and deletions are also included within the scope of the present invention.

1: Power management device 2: Vehicle storage battery 3: Residential (fixed) storage battery 4: System power supply 5: Renewable energy power supply (solar cell PV)
6: Energy distributor 7: Controller 8: Power conditioner 15: Maximum charge amount (discharge amount) allocation unit 16: In-vehicle battery charge priority selection unit 17: In-vehicle battery charge rate threshold setting unit 18: Comparison unit 19: Charge priority execution unit

Claims (3)

An on-board battery,
at least one residential battery;
a grid power source or a renewable energy power source;
an energy distributor that connects the system power supply or the renewable energy power supply to the vehicle storage battery and the residential storage battery, and distributes and supplies electric power to the vehicle storage battery or the residential storage battery;
a controller that controls the energy distributor and controls the amount of electricity stored in the vehicle storage battery and the amount of electricity stored in the residential storage battery based on a predetermined threshold value that is set in advance regarding the amount of electricity stored in the vehicle storage battery.
The controller
When a charging rate, which is a level of the amount of stored power of the charged vehicle-mounted storage battery relative to a storage battery capacity preset for the vehicle-mounted storage battery, is equal to or lower than a charging rate threshold value set by a user, which is one of the predetermined threshold values, the vehicle-mounted storage battery is given priority during charging, and the residential storage battery is given priority during discharging,
When the charging rate of the vehicle-mounted storage battery is greater than the charging rate threshold, the residential storage battery is given priority during charging, and the vehicle-mounted storage battery is given priority during discharging,
A power management device that selects a priority of charging and discharging between the vehicle storage battery and the residential storage battery based on the user's setting of a charging rate threshold . In claim 1 ,
a power management device that selects one of the in-vehicle storage battery and the residential storage battery to be charged, allocates a maximum charge amount of the grid power source or the renewable energy power source to the selected storage battery, and allocates a charge amount that is the difference between the maximum charge amount and the maximum charge amount of the selected storage battery to the unselected storage battery. In claim 1 ,
The power management device, wherein the energy distributor and the controller are installed in a power conditioner that converts power from the grid power supply or the renewable energy power supply.