Power conversion system and power conversion control device

Abstract

To provide a power conversion system capable of stably and continuously supplying power to a load even if a vehicle-mounted battery which is not sufficiently charged is included in a plurality of vehicle-mounted batteries when backup power supply to the load is executed by using the vehicle-mounted batteries of a plurality of vehicles at the time of power failure of a commercial power supply.SOLUTION: The power conversion system of the present invention includes a control unit configured to perform a first operation of supplying electric power to a load from both of a part of in-vehicle batteries included in a plurality of in-vehicle batteries and another part of in-vehicle batteries included in the plurality of in-vehicle batteries and having a value of a parameter indicating a remaining charge amount lower than that of the part of in-vehicle batteries, and a second operation of continuing power supply from the part of in-vehicle batteries to the load and switching an operation mode of the other part of in-vehicle batteries from discharging to charging when power consumption in the load decreases during the execution of the first operation.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a power conversion system and a power conversion control device. [Background technology]

[0002] With the spread of electric vehicles, power conversion systems that effectively utilize the drive batteries (hereinafter referred to as "vehicle batteries") installed in electric vehicles have been developed (see, for example, Patent Document 1). Patent Document 1 discloses a charging / discharging device that supplies power stored in the main battery of an electric vehicle to a residential load (hereinafter referred to as "backup power supply") during a commercial power outage. [Prior art documents] [Non-patent literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-61432 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, for loads (equipment) installed in an average household, backup power supply during a power outage can often be achieved using the onboard battery of a single electric vehicle. On the other hand, for example, in office buildings and commercial facilities where the load consumes a lot of power, multiple electric vehicles are required for backup power supply during a power outage. However, in emergencies, there may be situations where it is difficult to secure the required number of fully charged electric vehicles.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a power conversion system and a power conversion control device that, when performing backup power supply to a load (equipment) using onboard batteries of multiple vehicles during a commercial power outage, can continue to stably supply power to the load even if some of the multiple onboard batteries are not fully charged. [Means for solving the problem]

[0006] To solve the above problem, a power conversion system of the present invention is connected to a plurality of on-board batteries mounted on a plurality of vehicles, each of which is connected to a commercial power source, and a load. The power conversion system of the present invention is capable of converting AC power input from the commercial power source into DC power and supplying the DC power to each of the plurality of on-board batteries. The power conversion system of the present invention includes a control unit. In the event of a commercial power outage, the control unit is capable of performing a first operation to supply power to the load from both some on-board batteries included in the plurality of on-board batteries and some other on-board batteries included in the plurality of on-board batteries and having a parameter value representing a remaining charge amount lower than that of some of the on-board batteries. Furthermore, if power consumption in the load decreases while the first operation is being performed, the control unit is capable of performing a second operation to continue supplying power to the load from some of the on-board batteries and switch the operation mode of the other some of the on-board batteries from discharging to charging.

[0007] In order to solve the above problems, a power conversion control device of the present invention includes a control unit for the power conversion system of the present invention, and controls the operation of the power conversion device. The power conversion device is connected to a plurality of on-board batteries mounted on a plurality of vehicles, a commercial power source, and a load, and is capable of converting AC power input from the commercial power source into DC power and supplying the DC power to each of the plurality of on-board batteries. [Effects of the Invention]

[0008] According to the present invention having the above configuration, when backup power supply to a load (equipment) is performed using onboard batteries of multiple vehicles during a commercial power outage, power supply to the load can be continued stably even if one of the multiple onboard batteries is not fully charged. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a power conversion system according to a first embodiment of the present invention. [Figure 2]3A and 3B are diagrams showing the charging states of a plurality of on-board batteries in power conversion control examples 1 and 2 performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 3] FIG. 2 is a diagram showing the time-varying characteristics of the power consumption of a load and the charge / discharge power of each on-board battery in power conversion control example 1 performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 4] FIG. 10 is a diagram showing the time-varying characteristics of the consumed / regenerated power of the load and the charged / discharged power of each on-board battery in a second example of power conversion control performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 5] 5A and 5B are diagrams showing the charging states of a plurality of on-board batteries in power conversion control examples 3 and 4 performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 6] 10A and 10B are diagrams showing other examples of the state of charge of a plurality of on-board batteries in power conversion control examples 3 and 4 performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 7] FIG. 10 is a diagram showing the time-varying characteristics of the power consumption of the load and the charge / discharge power of each on-board battery in a power conversion control example 3 performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 8] FIG. 10 is a diagram showing the time-varying characteristics of the consumed / regenerated power of the load and the charged / discharged power of each on-board battery in a fourth example of power conversion control performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 9] 10A and 10B are diagrams showing the charging states of a plurality of on-board batteries in power conversion control examples 5 and 6 performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 10] FIG. 10 is a diagram showing the time-varying characteristics of the power consumption of the load and the charge / discharge power of each on-board battery in power conversion control example 5 performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 11] FIG. 10 is a diagram showing the time-varying characteristics of the consumed / regenerated power of the load and the charged / discharged power of each on-board battery in a sixth example of power conversion control performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 12] 10A and 10B are diagrams showing the charging states of a plurality of on-board batteries in power conversion control examples 7 and 8 performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 13] FIG. 10 is a diagram showing the time-varying characteristics of the power consumption of the load and the charge / discharge power of each on-board battery in power conversion control example 7 performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 14] FIG. 10 is a diagram showing the time-varying characteristics of the consumed / regenerated power of the load and the charged / discharged power of each on-board battery in power conversion control example 8 performed by the power conversion system according to the first embodiment of the present invention during a power outage. [Figure 15] FIG. 4 is a schematic configuration diagram of a power conversion system according to a second embodiment of the present invention. [Figure 16] FIG. 10 is a schematic configuration diagram of a power conversion system according to a third embodiment of the present invention. [Figure 17] FIG. 10 is a schematic configuration diagram of a power conversion system according to a fourth embodiment of the present invention. [Figure 18] FIG. 10 is a hardware configuration diagram of a computer device that can be used as a power conversion control device according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The configuration of a power conversion system according to various embodiments of the present invention and the power conversion control performed by the power conversion system when backup power is supplied from multiple electric vehicles to a load during a commercial power outage will be specifically described below with reference to the drawings.

[0011] 1. First embodiment [Power conversion system configuration] 1 is a schematic diagram of a power conversion system according to a first embodiment of the present invention. To simplify the explanation, only components related to power conversion control performed between a commercial power source and a load and multiple on-board batteries installed in multiple vehicles (electric vehicles) are shown.

[0012] 1, the power conversion system 1 includes a control unit 10, a first relay 11, a second relay 12, and three AC (Alternate Current) / DC (Direct Current) conversion units 13, 14, and 15. The power conversion system 1 also includes a first DC / DC conversion unit 16, a second DC / DC conversion unit 17, and a third DC / DC conversion unit 18.

[0013] In this embodiment, the power conversion system 1 is electrically connected to a commercial power source 2 (AC power source) and a power supply path switch 3, and the power supply path switch 3 is electrically connected to a load 4 (facility). The power conversion system 1 is also electrically connectable to three on-board batteries 5a, 6a, 7a (hereinafter referred to as the "first on-board battery 5a," the "second on-board battery 6a," and the "third on-board battery 7a") mounted on three electric vehicles 5, 6, 7 (hereinafter referred to as the "first electric vehicle 5," the "second electric vehicle 6," and the "third electric vehicle 7"), respectively.

[0014] The power supply path switch 3 is a device that switches the power supply path to the load 4. Specifically, the power supply path switch 3 connects the load 4 to the commercial power source 2 during normal operation when the commercial power source 2 is not experiencing a power outage, and connects the load 4 to the power conversion system 1 during a power outage. The load 4 is equipment that is the target of backup power supply during a power outage, and is assumed to include equipment such as elevators whose power consumption fluctuates significantly over time due to operation and shutdown. The load 4 may also include equipment (elevators, etc.) that not only consumes power but also generates regenerative power.

[0015] In the power conversion system 1, a component consisting of a first relay 11, a second relay 12, three AC / DC conversion units 13, 14, and 15, a first DC / DC conversion unit 16, a second DC / DC conversion unit 17, and a third DC / DC conversion unit 18 functions as a power conversion unit. Based on a control signal input from the control unit 10, each component in the power conversion unit performs power conversion operation between the commercial power supply 2 or the load 4 and the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a.

[0016] In this embodiment, an example will be described in which the number of electric vehicles connected to the power conversion system 1 is three, but the present invention is not limited to this, and for example, the number of electric vehicles connected to the power conversion system 1 may be two, or four or more.

[0017] Furthermore, in this embodiment, a configuration example is described in which the power conversion system 1 is provided with the same number of AC / DC conversion units as the number of electric vehicles connectable to the power conversion system 1, i.e., the same number of DC / DC conversion units. However, the present invention is not limited to this. For example, the power conversion system 1 may be provided with only one AC / DC conversion unit. However, in a configuration like this embodiment in which the same number of AC / DC conversion units as the number of DC / DC conversion units are provided, when increasing the number of electric vehicles connected to the power conversion system 1, it is sufficient to simply connect in parallel to the existing circuit in the power conversion system 1 circuits each consisting of one AC / DC conversion unit and one DC / DC conversion unit, for the number of electric vehicles to be added. Therefore, the configuration of this embodiment makes it easy to expand the scale of the power conversion system 1.

[0018] [Electrical connection of the power conversion system] 1, the control unit 10 is connected to the first relay 11, the second relay 12, the three AC / DC conversion units 13, 14, and 15, the first DC / DC conversion unit 16, the second DC / DC conversion unit 17, and the third DC / DC conversion unit 18. The control unit 10 outputs control signals to these components.

[0019] 1, the output terminal of the commercial power source 2 is connected to an input terminal on the commercial power source 2 side of the power supply path switch 3 and one of the input / output terminals of the first relay 11. Furthermore, the input / output terminal on the power conversion system 1 side of the power supply path switch 3 is connected to one of the input / output terminals of the second relay 12, and the input / output terminal on the load 4 side of the power supply path switch 3 is connected to the load 4. In other words, the power conversion system 1 and the commercial power source 2 are connected to the load 4 via the power supply path switch 3.

[0020] The other input / output terminal of the first relay 11 and the other input / output terminal of the second relay 12 are connected to input / output terminals on the AC power side of the three AC / DC conversion units 13, 14, and 15. The input / output terminals on the AC power side of the three AC / DC conversion units 13, 14, and 15 are connected to each other.

[0021] The input / output terminals on the DC power side of the three AC / DC conversion units 13, 14, and 15 are connected to each other and to one of the input / output terminals of the first DC / DC conversion unit 16. The input / output terminals on the DC power side of the three AC / DC conversion units 13, 14, and 15 are connected to one of the input / output terminals of the second DC / DC conversion unit 17. The input / output terminals on the DC power side of the three AC / DC conversion units 13, 14, and 15 are connected to one of the input / output terminals of the third DC / DC conversion unit 18.

[0022] The other input / output terminal of the first DC / DC conversion unit 16 is connected to the first vehicle battery 5a, the other input / output terminal of the second DC / DC conversion unit 17 is connected to the second vehicle battery 6a, and the other input / output terminal of the third DC / DC conversion unit 18 is connected to the third vehicle battery 7a.

[0023] [Configuration and operation of each part] (Control unit) Although not shown, the control unit 10 can be configured, for example, by a microcontroller (microprocessor) including a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and functions as an arithmetic processing device and a control device.

[0024] The control unit 10 controls the switching operations of the first relay 11, the second relay 12, and the power supply path switch 3, both during normal operation and during a power outage of the commercial power supply 2. The control unit 10 also controls the power conversion operations of the three AC / DC conversion units 13 to 15, the first DC / DC conversion unit 16, the second DC / DC conversion unit 17, and the third DC / DC conversion unit 18, both during normal operation and during a power outage of the commercial power supply 2.

[0025] (First and second relays) The first relay 11 switches on / off the input / output operation of AC power between the commercial power source 2 and the power conversion system 1 based on a control signal input from the control unit 10. The second relay 12 switches on / off the input / output operation of AC power between the load 4 and the power conversion system 1 based on a control signal input from the control unit 10.

[0026] (AC / DC conversion section) When the commercial power supply 2 is in a normal state, the three parallel-connected AC / DC converters 13-15 convert the AC power input from the commercial power supply 2 into DC power based on a control signal input from the control unit 10, and output the DC power to the in-vehicle battery side. When the commercial power supply 2 is in a normal state, the three AC / DC converters 13-15 convert the DC power input from the in-vehicle battery side into AC power based on a control signal input from the control unit 10, and output the converted AC power to the commercial power supply 2 side.

[0027] On the other hand, when the commercial power supply 2 experiences a power outage, the three AC / DC converters 13 to 15 convert the DC power input from the in-vehicle battery into AC power based on a control signal input from the control unit 10, and output the converted AC power to the load 4. Also, when the commercial power supply 2 experiences a power outage, the three AC / DC converters 13 to 15 convert the AC power input from the load 4 into DC power based on a control signal input from the control unit 10, and output the DC power to the in-vehicle battery.

[0028] In this embodiment, the three AC / DC conversion units 13 to 15 are each configured with the same converter, but some or all of the three AC / DC conversion units 13 to 15 may be configured with different converters.

[0029] (First to third DC / DC conversion units) When charging the first vehicle-mounted battery 5a, the first DC / DC converter 16 converts the DC power output from the three AC / DC converters 13-15 into DC power of a predetermined value based on a control signal input from the control unit 10, and outputs the DC power of the predetermined value to the first vehicle-mounted battery 5a. When discharging the first vehicle-mounted battery 5a, the first DC / DC converter 16 converts the DC power output from the first vehicle-mounted battery 5a into DC power of a specific value based on a control signal input from the control unit 10, and outputs the DC power of the specific value to the three AC / DC converters 13-15.

[0030] When charging the second vehicle-mounted battery 6a, the second DC / DC converter 17 converts the DC power output from the three AC / DC converters 13-15 into DC power of a predetermined value based on a control signal input from the control unit 10, and outputs the DC power of the predetermined value to the second vehicle-mounted battery 6a. When discharging the second vehicle-mounted battery 6a, the second DC / DC converter 17 converts the DC power output from the second vehicle-mounted battery 6a into DC power of a specific value based on a control signal input from the control unit 10, and outputs the DC power of the specific value to the three AC / DC converters 13-15.

[0031] When charging the third vehicle-mounted battery 7a, the third DC / DC converter 18 converts the DC power output from the three AC / DC converters 13-15 into DC power of a predetermined value based on a control signal input from the control unit 10, and outputs the DC power of the predetermined value to the third vehicle-mounted battery 7a. When discharging the third vehicle-mounted battery 7a, the third DC / DC converter 18 converts the DC power output from the third vehicle-mounted battery 7a into DC power of a specific value based on a control signal input from the control unit 10, and outputs the DC power of the specific value to the three AC / DC converters 13-15.

[0032] In this embodiment, the first DC / DC conversion unit 16, the second DC / DC conversion unit 17, and the third DC / DC conversion unit 18 are each configured with the same converter, but some or all of these three DC / DC conversion units may be configured with different converters.

[0033] [Outline of power conversion operation in a power conversion system] (normal times) When the commercial power supply 2 is in normal operation, the control unit 10 turns on the first relay 11 and turns off the second relay 12, switching the connection of the power supply path switch 3 to the commercial power supply 2 side. In this case, power is supplied from the commercial power supply 2 side to the load 4 and the power conversion system 1. Then, during normal operation, the control unit 10 controls the power conversion system 1 to perform the following power conversion between the commercial power supply 2 and each of the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a.

[0034] Under normal conditions, the three AC / DC converters 13-15 first convert AC power input from the commercial power supply 2 into DC power. Next, the first DC / DC converter 16, the second DC / DC converter 17, and the third DC / DC converter 18 each convert the DC power converted by the three AC / DC converters 13-15 into DC power of a predetermined value. The first DC / DC converter 16, the second DC / DC converter 17, and the third DC / DC converter 18 then supply the predetermined value of DC power to the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a, respectively. This power conversion operation allows each vehicle battery to be charged with power supplied from the commercial power supply 2.

[0035] Furthermore, during normal operation, the first DC / DC converter 16, the second DC / DC converter 17, and the third DC / DC converter 18 first convert the DC power output (discharged) from the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a, respectively, into DC power of a specific value. Next, the three AC / DC converters 13-15 convert the DC power output from the first DC / DC converter 16, the second DC / DC converter 17, and the third DC / DC converter 18 into AC power. The three AC / DC converters 13-15 then output the converted AC power to the commercial power source 2 via the first relay 11. Through this power conversion operation, the DC power output (discharged) from the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a can be used to adjust the power received from the commercial power source 2.

[0036] (During a power outage) When the commercial power supply 2 experiences a power outage, the control unit 10 turns off the first relay 11 and turns on the second relay 12, switching the connection of the power supply path switch 3 to the power conversion system 1 side. In this case, power is supplied to the load 4 from the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a via the power conversion system 1. Then, during a power outage, the control unit 10 controls the power conversion system 1 to perform the following power conversion between the load 4 and each of the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a.

[0037] During a power outage, the first DC / DC converter 16, the second DC / DC converter 17, and the third DC / DC converter 18 first convert the DC power output (discharged) from the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a into DC power of a specific value, respectively. Next, the three AC / DC converters 13-15 convert the DC power output from the first DC / DC converter 16, the second DC / DC converter 17, and the third DC / DC converter 18 into AC power. The three AC / DC converters 13-15 then output the converted AC power to the load 4 via the second relay 12 and the power supply path switch 3. In other words, in the power conversion system 1, even if the commercial power supply 2 experiences a power outage, backup power can be supplied to the load 4 using the power stored in the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a.

[0038] Furthermore, during a power outage, power is supplied from the in-vehicle battery with a sufficient charge margin among the first in-vehicle battery 5a, the second in-vehicle battery 6a, and the third in-vehicle battery 7a to the in-vehicle battery with an insufficient charge margin, depending on the power consumption or regenerated power of the load 4. That is, in this embodiment, during a power outage, the in-vehicle battery with an insufficient charge margin is charged with discharge power from the in-vehicle battery with an insufficient charge margin, depending on the power consumption or regenerated power of the load 4. The specific content of this power conversion operation will be described in detail later with reference to the drawings.

[0039] [Example of power conversion control in a power conversion system during a power outage] Next, various power conversion control examples (power conversion control examples 1 to 8 described below) performed by the power conversion system 1 of this embodiment when the commercial power supply 2 experiences a power outage will be described with reference to the drawings. The power conversion control processing in the various power conversion control examples described below is executed by the control unit 10 of the power conversion system 1.

[0040] (1) Power conversion control example 1 First, referring to Figures 2 and 3, a description will be given of power conversion control example 1 in the power conversion system 1 that is performed when the commercial power supply 2 experiences a power outage. Note that power conversion control example 1 describes a case in which the first electric vehicle 5 and the second electric vehicle 6 are present and the third electric vehicle 7 is absent at the time of the power outage, that is, a case in which the first on-board battery 5a and the second on-board battery 6a are connected to the power conversion system 1 but the third on-board battery 7a is not connected. Also, power conversion control example 1 describes a case in which the load 4 does not include a load (equipment) that generates regenerative power.

[0041] Fig. 2 is a diagram showing the state of charge of each on-board battery in power conversion control example 1. The SOC (State Of Charge) written on the vertical axis of the graph shown in Fig. 2 indicates the state of charge of the on-board battery, with the SOC value of a completely discharged on-board battery being "0" and the SOC value of a fully charged on-board battery being "1." In other words, the SOC (a parameter value representing the remaining charge amount) is a value representing the ratio of the remaining charge amount (remaining energy amount) to the fully charged amount of the on-board battery.

[0042] The third threshold Sth3 shown on the vertical axis of the graph in Fig. 2 is a value indicating the state of charge of the vehicle battery at the lower discharge limit, and if the SOC value of the vehicle battery is less than the third threshold Sth3, discharging operation of the vehicle battery is not possible. The second threshold Sth2 is a value greater than the third threshold Sth3 and is a threshold indicating whether the state of charge is at a sufficient margin relative to the third threshold Sth3 (lower discharge limit). The first threshold Sth1 is a value greater than the second threshold Sth2 and is a threshold indicating whether the state of charge is at an even greater margin relative to the third threshold Sth3 (lower discharge limit).

[0043] 2, in power conversion control example 1, the SOC value S1 of the first vehicle-mounted battery 5a is greater than the first threshold value Sth1 and less than 1, and the SOC value S2 of the second vehicle-mounted battery 6a is less than the second threshold value Sth2 and greater than the third threshold value Sth3. That is, in power conversion control example 1, the state of charge of the first vehicle-mounted battery 5a is in a state where there is a sufficient margin for the lower discharge limit, and the state of charge of the second vehicle-mounted battery 6a is in a state where there is not a margin for the lower discharge limit.

[0044] In this embodiment, the in-vehicle battery in a charged state where the SOC value is equal to or greater than the first threshold value Sth1 can supply power (charge) to the in-vehicle battery in a charged state where the SOC value is equal to or less than the second threshold value Sth2, depending on the consumed / regenerated power of the load 4 after a power outage. Hereinafter, the in-vehicle battery in a charged state where the SOC value is equal to or greater than the first threshold value Sth1 will be referred to as the "main in-vehicle battery," and the in-vehicle battery in a charged state where the SOC value is equal to or less than the second threshold value Sth2 will be referred to as the "sub in-vehicle battery." Therefore, in power conversion control example 1 (the example shown in FIG. 2 ), the first in-vehicle battery 5a serves as the main in-vehicle battery (one of the in-vehicle batteries), and the second in-vehicle battery 6a serves as the sub in-vehicle battery (the other one of the in-vehicle batteries). In this embodiment, the first in-vehicle battery 5a supplies power to the second in-vehicle battery 6a, charging the second in-vehicle battery 6a, depending on the operating status of the load 4 after a power outage.

[0045] The third threshold value Sth3 is set according to the specifications of the vehicle battery. Meanwhile, the first threshold value Sth1 and the second threshold value Sth2 are set in advance as appropriate according to, for example, the equipment included in the load 4, the number of vehicle batteries connected to the power conversion system 1, customer requests, etc. The meanings of the above-mentioned SOC threshold values, main vehicle battery, and sub vehicle battery are not limited to power conversion control example 1, but are the same in power conversion control examples 2 to 8 described below.

[0046] Figure 3 is a diagram showing the time-varying characteristics of the consumed / regenerated power Pld in the load 4 (hereinafter referred to as "power Pld of the load 4"), the power P1 charged / discharged (input / output) in the first vehicle battery 5a (hereinafter referred to as "power P1 of the first vehicle battery 5a"), and the power P2 charged / discharged in the second vehicle battery 6a (hereinafter referred to as "power P2 of the second vehicle battery 6a") after a power outage occurs in power conversion control example 1.

[0047] The horizontal axis of the time change characteristics of each power represents time, and the vertical axis represents power value. In the time change characteristics of the power P1 of the first vehicle battery 5a and the power P2 of the second vehicle battery 6a, positive values ​​represent discharge power values ​​and negative values ​​represent charge power values. In addition, in the time change characteristics of the power Pld of the load 4, positive values ​​represent power consumption values ​​and negative values ​​represent regenerative power values. Note that in power conversion control example 1, the load 4 does not include a load (equipment) that generates regenerative power, so the time change characteristics of the power Pld of the load 4 shown in Figure 3 only show positive values.

[0048] Furthermore, in the time change characteristics of each power shown in Figure 3, for convenience of explanation, the time change pattern of each power is shown in a step-like (discontinuous) pattern, but in reality, each power changes continuously over time (the same applies to power conversion control examples 2 to 8 described below).

[0049] In the time-varying characteristics of the power P1 of the first vehicle-mounted battery 5a shown in Figure 3, the power value Ph1 is the maximum discharge power of the first vehicle-mounted battery 5a, and the power value Pj1 is the maximum charge power of the first vehicle-mounted battery 5a. In addition, in the time-varying characteristics of the power P2 of the second vehicle-mounted battery 6a, the power value Ph2 is the maximum discharge power of the second vehicle-mounted battery 6a, and the power value Pj2 is the maximum charge power of the second vehicle-mounted battery 6a.

[0050] 3, the power value Pth1 is a threshold value (hereinafter referred to as "first threshold power Pth1") that is set appropriately depending on the state of charge of each on-board battery connected to the power conversion system 1 during a power outage. Specifically, the first threshold power Pth1 (predetermined threshold power) is a threshold value for determining whether the maximum discharge power supplied to the load 4 from the main on-board battery (SOC≧Sth1) that has a sufficient state of charge is insufficient and therefore power must also be supplied to the load 4 from the sub-on-board battery (SOC≦Sth2). Therefore, in power conversion control example 1, since the main on-board battery is the first on-board battery 5a, ignoring power conversion efficiency, the maximum discharge power Ph1 of the first on-board battery 5a can be set as the first threshold power Pth1 (≈Ph1) of the power Pld of the load 4.

[0051] In power conversion control example 1, when the power Pld of the load 4 is greater than the first threshold power Pth1, the power supply is insufficient even when the maximum discharge power Ph1 is supplied from the first vehicle battery 5a (main vehicle battery) to the load 4. Therefore, in this case, to continue backup power supply to the load 4, power is also supplied to the load 4 from the second vehicle battery 6a (sub-vehicle battery). Hereinafter, this power supply operation mode will be referred to as the "first operation mode" (first operation).

[0052] On the other hand, in power conversion control example 1, when the power Pld of the load 4 is smaller than the first threshold power Pth1, power is supplied to the load 4 only from the first vehicle battery 5a (main vehicle battery). At this time, power is also supplied from the first vehicle battery 5a to the second vehicle battery 6a (sub-vehicle battery), and the second vehicle battery 6a is charged. Hereinafter, this power supply operation mode will be referred to as the "second operation mode" (second operation).

[0053] The meanings of the threshold power, maximum power generation power, maximum charging power, power supply operation modes (first and second operation modes), etc. defined in the time-varying characteristics of each power described above are not limited to power conversion control example 1, but are the same in power conversion control examples 2 to 8 described below.

[0054] Here, a specific control operation in the power conversion system 1 in power conversion control example 1 will be described with reference to Fig. 3. In power conversion control example 1 shown in Fig. 3, an example will be described in which the value of the power Pld (power consumption) of the load 4 changes over time after a power outage occurs as follows.

[0055] First, after a power outage occurs, during a period T11 from time t10 to t11, the value of the power Pld of the load 4 becomes a value (Pld11) that is greater than 0 and less than the first threshold power Pth1, as shown in the time-varying characteristics of the power Pld of the load 4 in FIG. 3 . Next, the power Pld of the load 4 increases, and during a period T12 from time t11 to t12, the value of the power Pld of the load 4 becomes a value (Pld12) that is greater than the first threshold power Pth1. Next, the power Pld of the load 4 decreases, and during a period T13 from time t12 to t13, the value of the power Pld of the load 4 becomes a value (Pld13) that is greater than the first threshold power Pth1 and less than Pld12. Next, the power Pld of the load 4 decreases, and during a period T14 from time t13 to t14, the value of the power Pld of the load 4 becomes a value (Pld14) that is greater than 0 and less than the first threshold power Pth1. Next, the power Pld of the load 4 decreases, and in a period T15 after time t14, the value of the power Pld of the load 4 becomes a value (Pld15) that is greater than 0 and smaller than Pld14.

[0056] In power conversion control example 1, first, during period T11, the value (Pld11) of the power Pld of the load 4 is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T11, power is supplied from the first vehicle battery 5a (main vehicle battery) to the load 4 and the second vehicle battery 6a (sub-vehicle battery).

[0057] In the example shown in Figure 3, during period T11, the value of the power P1 of the first vehicle battery 5a (main vehicle battery) is set to the maximum discharge power Ph1 of the first vehicle battery 5a. At this time, power greater than the value (Pld11) of the power Pld of the load 4 is output (discharged) from the first vehicle battery 5a, and the output power (maximum discharge power Ph1) of the first vehicle battery 5a is supplied not only to the load 4 but also to the second vehicle battery 6a (sub-vehicle battery). Therefore, during period T11, the second vehicle battery 6a is in a charging state, and the value of the power P2 of the second vehicle battery 6a becomes a value (P211) less than 0 and greater than the negative value of the maximum charge power Pj2 of the second vehicle battery 6a.

[0058] Next, during period T12, the value of the power Pld of the load 4 (Pld12) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T12, power is supplied to the load 4 from both the first vehicle battery 5a (main vehicle battery) and the second vehicle battery 6a (sub-vehicle battery).

[0059] 3, during period T12, the value of the power P1 of the first vehicle battery 5a is maintained at the maximum discharge power Ph1. Also, during period T12, in order to continue backup power supply to the load 4, the second vehicle battery 6a supplies the load 4 with power that is insufficient with only the power supplied from the first vehicle battery 5a (Ph1). Therefore, during period T12, the value of the power P2 of the second vehicle battery 6a is set to a value (P212) that is greater than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a.

[0060] Next, during period T13, the value of the power Pld of the load 4 (Pld13) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T13 as well, power is supplied to the load 4 from both the first vehicle battery 5a (main vehicle battery) and the second vehicle battery 6a (sub-vehicle battery).

[0061] In the example shown in FIG. 3, during period T13, the value of the power P1 of the first vehicle battery 5a is maintained at the maximum discharge power Ph1. Furthermore, during period T13, in order to continue backup power supply to the load 4, the second vehicle battery 6a supplies the load 4 with power that is insufficient due to the power supply (Ph1) from the first vehicle battery 5a alone. Therefore, during period T13, the value of the power P2 of the second vehicle battery 6a is set to a value (P213) that is greater than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a. Note that the power consumption (Pld13) of the load 4 during period T13 is less than the power consumption (Pld12) of the load 4 during period T12, so the value of the power P2 of the second vehicle battery 6a during period T13 (P213) is also less than the value of the power P2 of the second vehicle battery 6a during period T12 (P212).

[0062] Next, during period T14, the value of the power Pld of the load 4 (Pld14) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T14, power is supplied from the first vehicle battery 5a (main vehicle battery) to the load 4 and the second vehicle battery 6a (sub-vehicle battery).

[0063] 3, during period T14, the value of the power P1 of the first vehicle battery 5a is maintained at the maximum discharge power Ph1. At this time, power greater than the value (Pld14) of the power Pld of the load 4 is output (discharged) from the first vehicle battery 5a, and the output power (maximum discharge power Ph1) of the first vehicle battery 5a is supplied not only to the load 4 but also to the second vehicle battery 6a. Therefore, during period T14, the second vehicle battery 6a is in a charging state, and the value of the power P2 of the second vehicle battery 6a becomes a value (P214) that is less than 0 and greater than the negative value of the maximum charge power Pj2 of the second vehicle battery 6a.

[0064] That is, in power conversion control example 1, when the power consumption of the load 4 decreases during operation (execution) of the first operation mode, and the value of the power Pld of the load 4 becomes smaller than the first threshold power Pth1, the operation mode of the power conversion system 1 switches to the second operation mode. As a result, the power supply from the first vehicle battery 5a (main vehicle battery) to the load 4 continues, but the operation mode of the second vehicle battery 6a (sub-vehicle battery) switches from discharging to charging.

[0065] During period T15, the value of the power Pld of the load 4 (Pld15) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T15 as well, power is supplied from the first vehicle battery 5a (main vehicle battery) to the load 4 and the second vehicle battery 6a (sub-vehicle battery).

[0066] 3, during period T15, the value of the power P1 of the first vehicle battery 5a is maintained at the maximum discharge power Ph1. At this time, power greater than the value (Pld15) of the power Pld of the load 4 is output (discharged) from the first vehicle battery 5a, and the output power (maximum discharge power Ph1) of the first vehicle battery 5a is supplied not only to the load 4 but also to the second vehicle battery 6a. Therefore, during period T15, the second vehicle battery 6a is in a charging state, and the value of the power P2 of the second vehicle battery 6a becomes a value (P215) that is less than 0 and greater than the negative value of the maximum charge power Pj2 of the second vehicle battery 6a. Furthermore, since the power consumption (Pld15) of the load 4 during period T15 is smaller than the power consumption (Pld14) of the load 4 during period T14, the absolute value (charging power) of the value (P215) of the power P2 of the second vehicle battery 6a during period T15 is greater than the absolute value (charging power) of the value (P214) of the power P2 of the second vehicle battery 6a during period T14.

[0067] In power conversion control example 1, after a power outage occurs, the discharge operation of the first vehicle battery 5a (main vehicle battery) and the charge / discharge operation of the second vehicle battery 6a (sub-vehicle battery) are controlled in the manner described above in response to fluctuations in the power Pld (power consumption) of the load 4.

[0068] If, after a power outage, the power conversion control of the present embodiment described above is not performed and instead the output power from the first vehicle battery 5a and the second vehicle battery 6a is controlled to be equal using, for example, a power balance control technique, the charging period for the second vehicle battery 6a is not provided. In this case, as the second vehicle battery 6a supplies (discharges) power to the load 4, the state of charge of the second vehicle battery 6a simply decreases over time. Then, as time passes, when the state of charge of the second vehicle battery 6a reaches its lower discharge limit, the second vehicle battery 6a can no longer discharge. In this state, if the power Pld of the load 4 exceeds the first threshold power Pth1, as in periods T12 and T13 in FIG. 3 , backup power supply to the load 4 cannot be continued even if the first vehicle battery 5a supplies the maximum discharge power Ph1 to the load 4.

[0069] In contrast, in the power conversion system 1 of this embodiment, when the value of the power Pld (power consumption) of the load 4 is less than the first threshold power Pth1, the second operating mode is activated, and power is supplied from the first vehicle battery 5a (main vehicle battery) with a sufficient state of charge to the second vehicle battery 6a (sub-vehicle battery) with a limited state of charge, thereby charging the second vehicle battery 6a. Therefore, even after a power outage occurs, when the power consumption of the load 4 is low, a period can be set in which the second vehicle battery 6a is charged by the first vehicle battery 5a, thereby increasing the state of charge of the second vehicle battery 6a. As a result, even when backup power is supplied to the load 4 by the first vehicle battery 5a and the second vehicle battery 6a after a power outage occurs, it is possible to prevent the state of charge of the second vehicle battery 6a from decreasing to the lower discharge limit, and the duration of backup power supply to the load 4 can be extended.

[0070] (2) Power conversion control example 2 Next, a second example of power conversion control in the power conversion system 1 performed when the commercial power supply 2 experiences a power outage will be described with reference to Fig. 4. As with the first example of power conversion control, the second example of power conversion control will be described for a case in which the first vehicle battery 5a and the second vehicle battery 6a are connected to the power conversion system 1 during a power outage, but the third vehicle battery 7a is not connected.

[0071] In addition, in power conversion control example 2, the charge states of the first vehicle battery 5a and the second vehicle battery 6a during a power outage are the same as those described in Fig. 2 (power conversion control example 1). That is, in power conversion control example 2, similar to power conversion control example 1, the first vehicle battery 5a serves as the main vehicle battery (one of the vehicle batteries) and the second vehicle battery 6a serves as the sub-vehicle battery (one of the other vehicle batteries).

[0072] However, in power conversion control example 2, a case will be described in which load 4 includes a load (equipment) that generates regenerative power. For example, elevators normally perform a powering operation in which input power is converted into mechanical energy, but some elevators are equipped with a regenerative function that converts mechanical energy into electrical power and outputs it in order to reduce power consumption. In power conversion control example 2, a case will be assumed in which load 4 includes an elevator with such a regenerative function.

[0073] Fig. 4 is a diagram showing the time change characteristics of the power Pld of the load 4, the power P1 of the first vehicle battery 5a, and the power P2 of the second vehicle battery 6a after a power outage occurs in power conversion control example 2. In the time change characteristics of the power Pld of the load 4 shown in Fig. 4, positive values ​​are power consumption values, and negative values ​​are regenerative power values.

[0074] Furthermore, in the time-varying characteristics of the power Pld of the load 4 shown in FIG. 4, the power value Pth2 is a threshold (hereinafter referred to as the "second threshold power Pth2") that is set appropriately depending on the state of charge of each on-board battery connected to the power conversion system 1 during a power outage. Specifically, the second threshold power Pth2 (specific threshold power) is a threshold for determining whether, even when maximum charging power is supplied from the load 4 to a sub-on-board battery that is not fully charged due to regenerative operation of equipment included in the load 4, there is surplus regenerated power that can be used to supply power to the main on-board battery. Therefore, in power conversion control example 2, since the sub-on-board battery is the second on-board battery 6a, ignoring power conversion efficiency, the maximum charging power Pj2 of the second on-board battery 6a can be set roughly as the second threshold power Pth2 (≈Pj2) of the power Pld of the load 4.

[0075] In power conversion control example 2, when the regenerative power of the load 4 (absolute value of Pld) is smaller than the second threshold power Pth2, power is supplied from both the load 4 and the first vehicle battery 5a (main vehicle battery) to the second vehicle battery 6a (sub-vehicle battery), and the second vehicle battery 6a is charged. In other words, when the regenerative power of the load 4 (absolute value of Pld) is smaller than the second threshold power Pth2, the sub-vehicle battery that is not in a fully charged state is charged preferentially. Hereinafter, this power supply operating mode will be referred to as the "third operating mode" (third operation).

[0076] On the other hand, in power conversion control example 2, when the regenerative power (absolute value of Pld) of the load 4 is greater than the second threshold power Pth2, power is supplied from the load 4 to both the first vehicle battery 5a (main vehicle battery) and the second vehicle battery 6a (sub-vehicle battery), and both vehicle batteries are charged. Hereinafter, this power supply operation mode will be referred to as the "fourth operation mode" (fourth operation). Note that when the fourth operation mode is activated, the second vehicle battery 6a (sub-vehicle battery), which has an insufficient state of charge, is charged at the maximum charging power Pj2. In other words, even in the fourth operation mode, the sub-vehicle battery, which has an insufficient state of charge, is charged preferentially.

[0077] In the second power conversion control example, similarly to the first power conversion control example, when the power consumption (Pld) of the load 4 is greater than the first threshold power Pth1, the power conversion system 1 operates in the first operation mode. When the power consumption (Pld) of the load 4 is less than the first threshold power Pth1, the power conversion system 1 operates in the second operation mode.

[0078] In the power conversion control example 2 shown in FIG. 4, an example will be described in which, after a power outage occurs, the value of the power Pld (consumed / regenerated power) of the load 4 fluctuates over time as follows.

[0079] First, after a power outage occurs, during a period T21 from time t20 to t21, the value of the power Pld of the load 4 becomes a value (Pld21) that is greater than 0 and less than the first threshold power Pth1, as shown in the time-varying characteristics of the power Pld of the load 4 in FIG. 4 . Next, the power Pld of the load 4 increases, and during a period T22 from time t21 to t22, the value of the power Pld of the load 4 becomes a value (Pld22) that is greater than the first threshold power Pth1. Next, the power Pld of the load 4 decreases, and during a period T23 from time t22 to t23, the value of the power Pld of the load 4 becomes a value (Pld23) that is greater than 0 and less than Pld21. Next, the power Pld of the load 4 decreases, and during a period T24 from time t23 to t24, the value of the power Pld of the load 4 becomes a value (Pld24) that is less than 0 and greater than the negative value of the second threshold power Pth2. Next, the power Pld of the load 4 decreases, and during a period T25 from time t24 to t25, the value of the power Pld of the load 4 becomes a value (Pld25) that is smaller than the negative value of the second threshold power Pth2. Next, the power Pld of the load 4 increases, and during a period T26 after time t25, the value of the power Pld of the load 4 becomes a value (Pld26) that is larger than the first threshold power Pth1.

[0080] 4, periods T24 and T25 are periods (power regeneration periods) in which power (regenerated power) is output from the load 4 due to the regenerative operation of equipment with a regenerative function included in the load 4, and during these periods, power is supplied from the load 4 to the power conversion system 1 (on-board battery side). Other periods are periods (power consumption periods) in which power is consumed by the load 4, and during these other periods, power is supplied from the power conversion system 1 to the load 4.

[0081] In power conversion control example 2, first, during period T21 (power consumption period), the value (Pld21) of the power Pld of the load 4 is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T21, power is supplied from the first vehicle battery 5a (main vehicle battery) to the load 4 and the second vehicle battery 6a (sub-vehicle battery).

[0082] 4, during period T21, the value of the power P1 of the first vehicle battery 5a is set to the maximum discharge power Ph1. At this time, because power greater than the value (Pld21) of the power Pld of the load 4 is output (discharged) from the first vehicle battery 5a, the output power (maximum discharge power Ph1) of the first vehicle battery 5a is supplied not only to the load 4 but also to the second vehicle battery 6a. Therefore, during period T21, the second vehicle battery 6a is in a charging state, and the value of the power P2 of the second vehicle battery 6a becomes a value (P221) that is less than 0 and greater than the negative value of the maximum charge power Pj2 of the second vehicle battery 6a.

[0083] Next, during period T22 (power consumption period), the value (Pld22) of the power Pld of the load 4 is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T22, power is supplied to the load 4 from both the first vehicle battery 5a (main vehicle battery) and the second vehicle battery 6a (sub-vehicle battery).

[0084] 4, during period T22, the value of the power P1 of the first vehicle battery 5a is maintained at the maximum discharge power Ph1. Also, during period T22, in order to continue backup power supply to the load 4, the second vehicle battery 6a supplies the load 4 with power that is insufficient when supplied with power (Ph1) from the first vehicle battery 5a alone. Therefore, during period T22, the value of the power P2 of the second vehicle battery 6a is set to a value (P222) that is less than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a.

[0085] Next, during period T23 (power consumption period), the value (Pld23) of the power Pld of the load 4 is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T23, power is supplied from the first vehicle battery 5a (main vehicle battery) to the load 4 and the second vehicle battery 6a (sub-vehicle battery).

[0086] In the example shown in Figure 4, during period T23, the value of the power P1 of the first vehicle battery 5a is maintained at the maximum discharge power Ph1. At this time, power greater than the value (Pld23) of the power Pld of the load 4 is output (discharged) from the first vehicle battery 5a, and therefore the output power (maximum discharge power Ph1) of the first vehicle battery 5a is supplied not only to the load 4 but also to the second vehicle battery 6a. Therefore, during period T23, the second vehicle battery 6a is in a charging state, and the value of the power P2 of the second vehicle battery 6a becomes a value (P223) that is less than 0 and greater than the negative value of the maximum charge power Pj2 of the second vehicle battery 6a. Furthermore, since the power consumption (Pld23) of the load 4 during period T23 is smaller than the power consumption (Pld21) of the load 4 during period T21, the absolute value (charging power) of the value (P223) of the power P2 of the second vehicle battery 6a during period T23 is greater than the absolute value (charging power) of the value (P221) of the power P2 of the second vehicle battery 6a during period T21.

[0087] That is, also in power conversion control example 2, when the power consumption of the load 4 decreases during operation (execution) of the first operation mode, and the value of the power Pld of the load 4 becomes smaller than the first threshold power Pth1, the operation mode of the power conversion system 1 switches to the second operation mode. As a result, the power supply from the first vehicle battery 5a (main vehicle battery) to the load 4 continues, but the operation mode of the second vehicle battery 6a (sub-vehicle battery) switches from discharging to charging.

[0088] Next, during period T24 (power regeneration period), the value (Pld24) of the power value Pld of the load 4 is greater than the negative value of the second threshold power Pth2, so the power conversion system 1 operates in the third operating mode. Therefore, during period T24, power is supplied to the second vehicle battery 6a (sub-vehicle battery) from both the load 4 and the first vehicle battery 5a (main vehicle battery), and the second vehicle battery 6a is charged.

[0089] In the example shown in Figure 4, during period T24, the value of the power P2 of the second vehicle battery 6a is set to a value (-Pj2) that is negative of the maximum charging power Pj2. Meanwhile, during period T24, the value of the power P1 of the first vehicle battery 5a is set to a value (Pl24) that is greater than 0 and less than the maximum discharging power Ph1 of the first vehicle battery 5a. At this time, the value (Pl24) of the power P1 of the first vehicle battery 5a is set so that the maximum charging power Pj2 is supplied to the second vehicle battery 6a from both the load 4 and the first vehicle battery 5a, i.e., so that the second vehicle battery 6a is charged with the maximum charging power Pj2.

[0090] Next, during period T25 (power regeneration period), the value of the power value Pld of the load 4 (Pld25) is smaller than the negative value of the second threshold power Pth2, so the power conversion system 1 operates in the fourth operating mode. Therefore, during period T25, power is supplied from the load 4 to the first vehicle battery 5a (main vehicle battery) and the second vehicle battery 6a (sub vehicle battery), and both vehicle batteries are charged.

[0091] In the example shown in Figure 4, during period T25, the value of the power P2 of the second vehicle battery 6a is maintained at a value (-Pj2) that is negative of the maximum charging power Pj2. Furthermore, at this time, because the regenerative power output from the load 4 is greater than the maximum charging power Pj2 of the second vehicle battery 6a, even if the maximum charging power Pj2 is supplied from the load 4 to the second vehicle battery 6a, there is surplus regenerative power. Therefore, during period T25, the surplus regenerative power is supplied to the first vehicle battery 5a, and the first vehicle battery 5a is charged, so the value of the power P1 of the first vehicle battery 5a becomes a value (P125) that is less than 0 and greater than the negative value of the maximum charging power Pj1 of the first vehicle battery 5a.

[0092] That is, in power conversion control example 2, when the power (regenerative power) output from the load 4 increases during operation (execution) of the third operation mode, and the absolute value of the power Pld of the load 4 becomes larger than the second threshold power Pth2, the operation mode of the power conversion system 1 switches to the fourth operation mode. As a result, the power supply from the load 4 to the second vehicle battery 6a (sub-vehicle battery) continues, but the operation mode of the first vehicle battery 5a (main vehicle battery) switches from discharging to charging.

[0093] During period T26 (power consumption period), the value of the power Pld of the load 4 (Pld26) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T26, power is supplied to the load 4 from both the first vehicle battery 5a (main vehicle battery) and the second vehicle battery 6a (sub-vehicle battery).

[0094] 4, during period T26, the value of the power P1 of the first vehicle battery 5a is set to the maximum discharge power Ph1. Also, during period T26, in order to continue backup power supply to the load 4, the second vehicle battery 6a supplies the load 4 with power that is insufficient with only the power supplied from the first vehicle battery 5a (Ph1). Therefore, during period T26, the value of the power P2 of the second vehicle battery 6a is set to a value (P226) that is less than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a.

[0095] In power conversion control example 2, after a power outage occurs, the charging / discharging operations of the first vehicle battery 5a (main vehicle battery) and the second vehicle battery 6a (sub vehicle battery) are controlled in the manner described above in response to fluctuations in the power Pld (consumed / regenerated power) of the load 4.

[0096] In power conversion control example 2, as described above, when the value of the power Pld of the load 4 is less than the first threshold power Pth1 during the power consumption period of the load 4, the second operation mode is activated, similar to power conversion control example 1. That is, power is supplied from the first vehicle battery 5a (main vehicle battery) that has a sufficient charge margin to the second vehicle battery 6a (sub-vehicle battery) that has a limited charge margin, and the second vehicle battery 6a is charged. Therefore, in power conversion control example 2, similar to power conversion control example 1, the duration of backup power supply to the load 4 after a power outage can be extended.

[0097] Furthermore, in power conversion control example 2, during a power regeneration period of the load 4, the second vehicle battery 6a (sub-vehicle battery) or both the first vehicle battery 5a (main vehicle battery) and the second vehicle battery 6a are charged with regenerative power output from the load 4. Specifically, when the power supplied from the load 4 (regenerative power) is smaller than the second threshold power Pth2, the third operation mode is activated, and the second vehicle battery 6a is charged with power output from both the load 4 and the first vehicle battery 5a. Furthermore, when the power supplied from the load 4 (regenerative power) is greater than the second threshold power Pth2, the fourth operation mode is activated, and both the first vehicle battery 5a and the second vehicle battery 6a are charged with power output from the load 4 (regenerative power). Therefore, in power conversion control example 2, the duration of backup power supply to the load 4 after a power outage can be further extended than in power conversion control example 1.

[0098] (3) Power conversion control example 3 Next, referring to Figures 5 to 7, a third example of power conversion control in the power conversion system 1 that is performed when the commercial power supply 2 experiences a power outage will be described. As with the first power conversion control example 1, the third power conversion control example 3 describes a case in which the first vehicle battery 5a and the second vehicle battery 6a are connected to the power conversion system 1 during a power outage, but the third vehicle battery 7a is not connected. As with the first power conversion control example 1, the third power conversion control example 3 also describes a case in which the load 4 does not include a load (equipment) that generates regenerative power.

[0099] FIG. 5 is a diagram showing the state of charge of each vehicle battery in power conversion control example 3. In power conversion control example 3, as shown in FIG. 5, the SOC value S1 of the first vehicle battery 5a is greater than the first threshold value Sth1 and less than 1, and the SOC value S2 of the second vehicle battery 6a is less than the first threshold value Sth1 and greater than the second threshold value Sth2. In other words, the example shown in FIG. 5 shows a case where the second vehicle battery 6a also has a relatively large margin of charge relative to the lower discharge limit (third threshold value Sth3). Therefore, in the example shown in FIG. 5, the relationship between the main vehicle battery and the sub-vehicle battery described in power conversion control examples 1 and 2 above does not hold between the first vehicle battery 5a and the second vehicle battery 6a.

[0100] FIG. 6 is a diagram showing another example of the state of charge of each vehicle battery in power conversion control example 3. In the example shown in FIG. 6, the SOC value S1 of the first vehicle battery 5a is smaller than the first threshold value Sth1 and larger than the second threshold value Sth2, and the SOC value S2 of the second vehicle battery 6a is smaller than the second threshold value Sth2 and larger than the third threshold value Sth3. That is, the example shown in FIG. 6 shows a case where the second vehicle battery 6a has no margin for charge and is not sufficiently charged to charge the second vehicle battery 6a. Therefore, even in the example shown in FIG. 6, the relationship between the main vehicle battery and the sub-vehicle battery described in power conversion control examples 1 and 2 above does not hold between the first vehicle battery 5a and the second vehicle battery 6a.

[0101] 5 and 6, in the event of a power outage, power is not supplied from the first vehicle battery 5a with a higher state of charge to the second vehicle battery 6a with a lower state of charge. In other words, in the event of a power outage, the first vehicle battery 5a is not discharged in order to charge the second vehicle battery 6a. Therefore, in power conversion control example 3, the load 4 does not output regenerative power, and therefore there is no charging period for the second vehicle battery 6a after a power outage occurs.

[0102] Furthermore, in power conversion control example 3, when the value of the power Pld (power consumption) of the load 4 is smaller than the first threshold power Pth1, power is supplied to the load 4 only from the first vehicle battery 5a with a higher state of charge. At this time, the second vehicle battery 6a with a lower state of charge does not perform charging / discharging operations. Hereinafter, this power supply operating mode will be referred to as the "fifth operating mode." On the other hand, when the value of the power Pld (power consumption) of the load 4 is larger than the first threshold power Pth1, the above-mentioned first operating mode is activated, and power is supplied to the load 4 from both the first vehicle battery 5a and the second vehicle battery 6a to continue backup power supply to the load 4.

[0103] Fig. 7 is a diagram showing the time change characteristics of the power Pld of the load 4, the power P1 of the first vehicle battery 5a, and the power P2 of the second vehicle battery 6a after a power outage occurs in power conversion control example 3. In power conversion control example 3 shown in Fig. 7, an example is described in which the value of the power Pld (power consumption) of the load 4 changes over time after a power outage occurs as follows.

[0104] First, after a power outage occurs, during a period T31 from time t30 to t31, the value of the power Pld of the load 4 becomes a value (Pld31) that is greater than 0 and less than the first threshold power Pth1, as shown in the time-varying characteristics of the power Pld of the load 4 in Figure 7. Next, the power Pld of the load 4 increases, and during a period T32 from time t31 to t32, the value of the power Pld of the load 4 becomes a value (Pld32) that is greater than the first threshold power Pth1. Next, the power Pld of the load 4 decreases, and during a period T33 from time t32 to t33, the value of the power Pld of the load 4 becomes a value (Pld33) that is greater than the first threshold power Pth1 and less than Pld32. Next, the power Pld of the load 4 decreases, and during a period T34 from time t33 to t34, the value of the power Pld of the load 4 becomes a value (Pld34) that is greater than 0 and less than the first threshold power Pth1. Next, the power Pld of the load 4 decreases, and in a period T35 after time t34, the value of the power Pld of the load 4 becomes a value (Pld35) that is greater than 0 and smaller than Pld34.

[0105] In power conversion control example 3, first, during period T31, the value of the power Pld of the load 4 (Pld31) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the fifth operating mode. Therefore, during period T31, power is supplied to the load 4 only from the first vehicle battery 5a with a high state of charge, and no discharging operation is performed from the second vehicle battery 6a with a low state of charge.

[0106] 7, during period T31, the value of the power P2 of the second vehicle battery 6a is set to 0, and no discharging operation is performed on the second vehicle battery 6a. Meanwhile, during period T31, the value of the power P1 of the first vehicle battery 5a is set to a value (P131) that is greater than 0 and less than the maximum discharge power Ph1. At this time, the value (P131) of the power P1 output from the first vehicle battery 5a is set to a value equivalent to the value (Pld31) of the power Pld of the load 4 during period T31.

[0107] Next, during period T32, the value of the power Pld of the load 4 (Pld32) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T32, power is supplied to the load 4 from both the first vehicle battery 5a and the second vehicle battery 6a.

[0108] 7, during period T32, the value of the power P1 of the first vehicle battery 5a is set to the maximum discharge power Ph1. Also, during period T32, in order to continue backup power supply to the load 4, the second vehicle battery 6a supplies the load 4 with power that is insufficient when the power supplied from the first vehicle battery 5a (Ph1) alone is not enough. Therefore, during period T32, the value of the power P2 of the second vehicle battery 6a is set to a value (P232) that is less than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a.

[0109] Next, during period T33, the value of the power Pld of the load 4 (Pld33) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T33 as well, power is supplied to the load 4 from both the first vehicle battery 5a and the second vehicle battery 6a.

[0110] In the example shown in FIG. 7, during period T33, the value of the power P1 of the first vehicle battery 5a is maintained at the maximum discharge power Ph1. Furthermore, during period T33, in order to continue backup power supply to the load 4, the second vehicle battery 6a supplies the load 4 with power that is insufficient for the power supplied from the first vehicle battery 5a (Ph1). Therefore, during period T33, the value of the power P2 of the second vehicle battery 6a is set to a value (P233) that is less than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a. Note that the power consumption (Pld33) of the load 4 during period T33 is less than the power consumption (Pld32) of the load 4 during period T32, so the value of the power P2 of the second vehicle battery 6a during period T33 (P233) is also less than the value of the power P2 of the second vehicle battery 6a during period T32 (P232).

[0111] Next, during period T34, the value of the power Pld of the load 4 (Pld34) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the fifth operating mode. Therefore, during period T34, power is supplied to the load 4 only from the first vehicle battery 5a with a high state of charge, and no discharging operation is performed from the second vehicle battery 6a with a low state of charge.

[0112] 7, during period T34, the value of the power P2 of the second vehicle battery 6a is set to 0, and no discharging operation is performed on the second vehicle battery 6a. Meanwhile, during period T34, the value of the power P1 of the first vehicle battery 5a is set to a value (P134) that is greater than 0 and less than the maximum discharge power Ph1. At this time, the value (P134) of the power P1 output from the first vehicle battery 5a is set to a value equivalent to the value (Pld34) of the power Pld of the load 4 during period T34.

[0113] During period T35, the value of the power Pld of the load 4 (Pld35) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the fifth operating mode. Therefore, during period T35, power is supplied to the load 4 only from the first vehicle battery 5a with a high state of charge, and no discharging operation is performed from the second vehicle battery 6a with a low state of charge.

[0114] In the example shown in Figure 7, during period T35, the value of the power P2 of the second vehicle battery 6a is set to 0, and no discharging operation is performed on the second vehicle battery 6a. Meanwhile, during period T35, the value of the power P1 of the first vehicle battery 5a is set to a value (P135) greater than 0 and less than the maximum discharge power Ph1. At this time, the value of the power P1 output from the first vehicle battery 5a (P135) is set to a value equivalent to the value (Pld35) of the power Pld of the load 4 during period T35. Note that the power consumption (Pld35) of the load 4 during period T35 is less than the power consumption (Pld34) of the load 4 during period T34, so the value (P135) of the power P1 of the first vehicle battery 5a during period T35 is also less than the value (P134) of the power P1 of the first vehicle battery 5a during period T34.

[0115] In power conversion control example 3, after a power outage occurs, the discharge operations of the first vehicle battery 5a and the second vehicle battery 6a are controlled in the manner described above in response to fluctuations in the power Pld (power consumption) of the load 4.

[0116] In power conversion control example 3, as described above, when the value of the load 4 power Pld is smaller than the first threshold power Pth1, the fifth operating mode is activated and the second vehicle battery 6a, which has a lower state of charge than the first vehicle battery 5a, is not discharged. Therefore, while the value of the load 4 power Pld is smaller than the first threshold power Pth1, the state of charge of the second vehicle battery 6a does not decrease, and the duration of backup power supply to the load 4 after a power outage can be extended.

[0117] (4) Power conversion control example 4 Next, referring to Fig. 8, a fourth example of power conversion control in the power conversion system 1 performed when the commercial power supply 2 experiences a power outage will be described. As with the first power conversion control example 1, the fourth example of power conversion control will be described in the case where the first vehicle battery 5a and the second vehicle battery 6a are connected to the power conversion system 1 during a power outage, but the third vehicle battery 7a is not connected. As with the second power conversion control example 2, the fourth example of power conversion control will be described in the case where the load 4 includes a load (equipment) that generates regenerative power. Furthermore, in the fourth example of power conversion control, the charge states of the first vehicle battery 5a and the second vehicle battery 6a during a power outage are the same as those described in Fig. 5 or 6 (third example of power conversion control).

[0118] Therefore, in Power Conversion Control Example 4, the operation during the power consumption period of the load 4 is the same as that of Power Conversion Control Example 3. That is, when the value of the power Pld of the load 4 during the power consumption period of the load 4 is smaller than the first threshold power Pth1, the fifth operation mode described above is activated, and power is supplied to the load 4 only from the first vehicle battery 5a with a higher state of charge, and no discharging operation is performed from the second vehicle battery 6a with a lower state of charge. On the other hand, when the value of the power Pld of the load 4 during the power consumption period of the load 4 is larger than the first threshold power Pth1, the first operation mode described above is activated, and power is supplied to the load 4 from both the first vehicle battery 5a and the second vehicle battery 6a to continue backup power supply to the load 4.

[0119] Furthermore, in power conversion control example 4, during the regenerative power period of the load 4, if the value of the regenerative power output from the load 4 (absolute value of Pld) is smaller than the second threshold power Pth2, power is supplied from the load 4 only to the second vehicle battery 6a with a lower state of charge, and only the second vehicle battery 6a is charged. At this time, no charging / discharging operation is performed on the first vehicle battery 5a with a higher state of charge. Hereinafter, this power supply operating mode will be referred to as the "sixth operating mode." On the other hand, if the value of the regenerative power output from the load 4 (absolute value of Pld) is greater than the second threshold power Pth2, the above-mentioned fourth operating mode is activated, and power is supplied from the load 4 to the first vehicle battery 5a and the second vehicle battery 6a, and both vehicle batteries are charged.

[0120] Fig. 8 is a diagram showing the time change characteristics of the power Pld of the load 4, the power P1 of the first vehicle battery 5a, and the power P2 of the second vehicle battery 6a after a power outage occurs in power conversion control example 4. In power conversion control example 4 shown in Fig. 8, an example is described in which the value of the power Pld (consumed / regenerated power) of the load 4 changes over time after a power outage occurs as follows:

[0121] First, after a power outage occurs, during a period T41 from time t40 to t41, the value of the power Pld of the load 4 becomes a value (Pld41) that is greater than 0 and less than the first threshold power Pth1, as shown in the time-varying characteristics of the power Pld of the load 4 in FIG. 8. Next, the power Pld of the load 4 increases, and during a period T42 from time t41 to t42, the value of the power Pld of the load 4 becomes a value (Pld42) that is greater than the first threshold power Pth1. Next, the power Pld of the load 4 decreases, and during a period T43 from time t42 to t43, the value of the power Pld of the load 4 becomes a value (Pld43) that is greater than 0 and less than Pld41. Next, the power Pld of the load 4 decreases, and during a period T44 from time t43 to t44, the value of the power Pld of the load 4 becomes a value (Pld44) that is less than 0 and greater than the negative value of the second threshold power Pth2. Next, the power Pld of the load 4 decreases, and during a period T45 from time t44 to t45, the value of the power Pld of the load 4 becomes a value (Pld45) that is smaller than the negative value of the second threshold power Pth2. Next, the power Pld of the load 4 increases, and during a period T46 after time t45, the value of the power Pld of the load 4 becomes a value (Pld46) that is larger than the first threshold power Pth1 and smaller than Pld42.

[0122] 8, periods T44 and T45 are power regeneration periods, during which power is supplied from the load 4 to the power conversion system 1 (on-board battery side). Other periods are power consumption periods, during which power is supplied from the power conversion system 1 to the load 4.

[0123] In power conversion control example 4, first, during period T41 (power consumption period), the value of power Pld of load 4 (Pld41) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the fifth operating mode. Therefore, during period T41, power is supplied to the load 4 only from the first vehicle battery 5a with a high state of charge, and no charging / discharging operation is performed on the second vehicle battery 6a with a low state of charge.

[0124] 8, during period T41, the value of the power P2 of the second vehicle battery 6a is set to 0, and no charging / discharging operation is performed on the second vehicle battery 6a. Meanwhile, during period T41, the value of the power P1 of the first vehicle battery 5a is set to a value (P141) that is greater than 0 and less than the maximum discharge power Ph1. At this time, the value (P141) of the power P1 output from the first vehicle battery 5a is set to a value equivalent to the value (Pld41) of the power Pld of the load 4 during period T41.

[0125] Next, during period T42 (power consumption period), the value of the power Pld of the load 4 (Pld42) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T42, power is supplied to the load 4 from both the first vehicle battery 5a and the second vehicle battery 6a.

[0126] 8, during period T42, the value of the power P1 of the first vehicle battery 5a is set to the maximum discharge power Ph1. Also, during period T42, in order to continue backup power supply to the load 4, the second vehicle battery 6a supplies the load 4 with power that is insufficient when the power supplied from the first vehicle battery 5a (Ph1) alone is not enough. Therefore, during period T42, the value of the power P2 of the second vehicle battery 6a is set to a value (P242) that is less than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a.

[0127] Next, during period T43 (power consumption period), the value of the power Pld of the load 4 (Pld43) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the fifth operating mode. Therefore, during period T43, power is supplied to the load 4 only from the first vehicle battery 5a with a high state of charge, and no charging / discharging operation is performed on the second vehicle battery 6a with a low state of charge.

[0128] In the example shown in Figure 8, during period T43, the value of the power P2 of the second in-vehicle battery 6a is set to 0, and no charging / discharging operation is performed on the second in-vehicle battery 6a. Meanwhile, during period T43, the value of the power P1 of the first in-vehicle battery 5a is set to a value (P143) greater than 0 and less than the maximum discharge power Ph1. At this time, the value (P143) of the power P1 output from the first in-vehicle battery 5a is set to a value equivalent to the value (Pld43) of the power Pld of the load 4 during period T43. Note that the power consumption (Pld43) of the load 4 during period T43 is less than the power consumption (Pld41) of the load 4 during period T41, so the value (P143) of the power P1 of the first in-vehicle battery 5a during period T43 is also less than the value (P141) of the power P1 of the first in-vehicle battery 5a during period T41.

[0129] Next, during period T44 (power regeneration period), the value of the power Pld of the load 4 (Pld44) is greater than the negative value of the second threshold power Pth2, so the power conversion system 1 operates in the sixth operating mode. Therefore, during period T44, power is supplied from the load 4 only to the second vehicle battery 6a with a low state of charge, and only the second vehicle battery 6a is charged. At this time, no charging / discharging operations are performed on the first vehicle battery 5a with a high state of charge.

[0130] 8, during period T44, the value of the power P1 of the first vehicle battery 5a is set to 0, and no charging / discharging operation is performed on the first vehicle battery 5a. Meanwhile, during period T44, the value of the power P2 of the second vehicle battery 6a becomes a value (P244) that is less than 0 and greater than the negative value of the maximum charging power Pj2 of the second vehicle battery 6a. At this time, the absolute value (charging power) of the value of the power P2 (P244) of the second vehicle battery 6a becomes a value equivalent to the absolute value of the value (Pld44) of the power Pld of the load 4 during period T43.

[0131] Next, during period T45 (power regeneration period), the value of the power value Pld of the load 4 (Pld45) is smaller than the negative value of the second threshold power Pth2, so the power conversion system 1 operates in the fourth operating mode. Therefore, during period T45, power is supplied from the load 4 to the first vehicle battery 5a and the second vehicle battery 6a, and both vehicle batteries are charged.

[0132] 8, during period T45, the value of the power P2 of the second vehicle battery 6a is set to the negative value (-Pj2) of the maximum charging power Pj2. At this time, the regenerative power output from the load 4 is greater than the maximum charging power Pj2 of the second vehicle battery 6a, so even if the maximum charging power Pj2 is supplied from the load 4 to the second vehicle battery 6a, there will be surplus regenerative power. Therefore, during period T45, the surplus regenerative power is supplied to the first vehicle battery 5a, and the first vehicle battery 5a is charged, so the value of the power P1 of the first vehicle battery 5a becomes a value (P145) that is less than 0 and greater than the maximum charging power Pj1 of the first vehicle battery 5a.

[0133] During period T46 (power consumption period), the value of the power Pld of the load 4 (Pld46) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T46, power is supplied to the load 4 from both the first vehicle battery 5a and the second vehicle battery 6a.

[0134] In the example shown in FIG. 8, during period T46, the value of the power P1 of the first vehicle battery 5a is set to the maximum discharge power Ph1. Also, during period T46, in order to continue backup power supply to the load 4, the second vehicle battery 6a supplies the load 4 with power that is insufficient for the power supplied from the first vehicle battery 5a (Ph1). Therefore, during period T46, the value of the power P2 of the second vehicle battery 6a is set to a value (P246) that is less than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a. In this case, because the power consumption (Pld46) of the load 4 during period T46 is less than the power consumption (Pld42) of the load 4 during period T42, the value of the power P2 of the second vehicle battery 6a during period T46 (P246) is also less than the value of the power P1 (P242) of the second vehicle battery 6a during period T42.

[0135] In power conversion control example 4, after a power outage occurs, the charging / discharging operations of the first vehicle battery 5a and the second vehicle battery 6a are controlled in the manner described above in response to fluctuations in the power Pld (consumed / regenerated power) of the load 4.

[0136] In power conversion control example 4, as described above, when the value of the power Pld of the load 4 is smaller than the first threshold power Pth1 during the power consumption period of the load 4, the fifth operation mode is activated and the discharge operation of the second vehicle battery 6a, which has a lower state of charge than the first vehicle battery 5a, is not performed. Therefore, during the power consumption period when the value of the power Pld of the load 4 is smaller than the first threshold power Pth1, the state of charge of the second vehicle battery 6a does not decrease, and as with power conversion control example 3 above, the duration of backup power supply to the load 4 can be extended.

[0137] Furthermore, in power conversion control example 4, as described above, during the power regeneration period of the load 4, when the value of the power Pld of the load 4 is smaller than the second threshold power Pth2, the fifth operation mode is activated, and power is supplied from the load 4 to the second vehicle battery 6a with a lower state of charge, and charging / discharging operations are not performed on the first vehicle battery 5a with a higher state of charge. Therefore, during the power regeneration period when the value of the power Pld of the load 4 is smaller than the second threshold power Pth2, the second vehicle battery 6a with a lower state of charge is charged preferentially, and the state of charge of the first vehicle battery 5a with a higher state of charge is not reduced. On the other hand, during the power regeneration period of the load 4, when the value of the power Pld of the load 4 is greater than the second threshold power Pth2, the fourth operation mode is activated, and power is supplied from the load 4 to the first vehicle battery 5a and the second vehicle battery 6a, and both vehicle batteries are charged. Therefore, in the fourth power conversion control example, the duration of backup power supply to the load 4 can be further extended compared to the third power conversion control example.

[0138] (5) Power conversion control example 5 Next, a fifth example of power conversion control in the power conversion system 1 that is performed when the commercial power supply 2 experiences a power outage will be described with reference to Figures 9 and 10. Note that the fifth example of power conversion control will be described assuming that the first electric vehicle 5, the second electric vehicle 6, and the third electric vehicle 7 are present at the time of the power outage, i.e., the first on-board battery 5a, the second on-board battery 6a, and the third on-board battery 7a are connected to the power conversion system 1. Furthermore, in the fifth example of power conversion control, similar to the first example of power conversion control, the case will be described where the load 4 does not include a load (equipment) that generates regenerative power.

[0139] Fig. 9 is a diagram showing the state of charge of each vehicle-mounted battery in power conversion control example 5. In power conversion control example 5, as shown in Fig. 9, the SOC value S1 of the first vehicle-mounted battery 5a is greater than the first threshold value Sth1 and less than 1, the SOC value S2 of the second vehicle-mounted battery 6a is less than the second threshold value Sth2 and greater than the third threshold value Sth3, and the SOC value S3 of the third vehicle-mounted battery 7a is greater than the first threshold value Sth1 and less than 1.

[0140] In this case, the main vehicle batteries (some of the vehicle batteries) with a charge state that is sufficiently large relative to the third threshold Sth3 (lower discharge limit) are the first vehicle battery 5a and the third vehicle battery 7a, and the sub vehicle batteries (other some of the vehicle batteries) with a charge state that is not large relative to the third threshold Sth3 are the second vehicle battery 6a. Therefore, in this example, ignoring power conversion efficiency, the maximum discharge power of the main vehicle batteries, i.e., the sum of the maximum discharge power Ph1 of the first vehicle battery 5a and the maximum discharge power Ph3 of the third vehicle battery 7a, can be set as the first threshold power Pth1 (≈Ph1+Ph3) for the power Pld of the load 4.

[0141] In power conversion control example 5, when the power Pld of the load 4 is greater than the first threshold power Pth1, the power conversion system 1 operates in the first operation mode described above. On the other hand, when the power Pld of the load 4 is less than the first threshold power Pth1, the power conversion system 1 operates in the second operation mode described above.

[0142] FIG. 10 is a diagram showing the time change characteristics of the power Pld of the load 4, the power P1 of the first in-vehicle battery 5a, the power P2 of the second in-vehicle battery 6a, and the power P3 charged / discharged by the third in-vehicle battery 7a (hereinafter referred to as "the power P3 of the third in-vehicle battery 7a") after a power outage occurs in power conversion control example 5. In the example shown in FIG. 10, in the time change characteristics of the power P3 of the third in-vehicle battery 7a, positive values ​​are discharge power values ​​and negative values ​​are charge power values. In addition, in the time change characteristics of the power P1 of the third in-vehicle battery 7a, the power value Ph3 is the maximum discharge power of the third in-vehicle battery 7a, and the power value Pj3 is the maximum charge power of the third in-vehicle battery 7a.

[0143] In the power conversion control example 5 shown in FIG. 10, an example will be described in which the value of the power Pld (power consumption) of the load 4 fluctuates over time after a power outage occurs as follows.

[0144] First, after a power outage occurs, during a period T51 from time t50 to t51, the value of the power Pld of the load 4 becomes greater than 0 and less than the first threshold power Pth1 (Pld51), as shown in the time change characteristics of the power Pld of the load 4 in Figure 10. Next, the power Pld of the load 4 increases, and during a period T52 from time t51 to t52, the value of the power Pld of the load 4 becomes greater than Pld51 and less than the first threshold power Pth1 (Pld52). Next, the power Pld of the load 4 increases, and during a period T53 from time t52 to t53, the value of the power Pld of the load 4 becomes greater than the first threshold power Pth1 (Pld53). Next, the power Pld of the load 4 decreases, and during a period T54 from time t53 to t54, the value of the power Pld of the load 4 becomes greater than 0 and less than Pld52 (Pld54). Next, the power Pld of the load 4 increases, and in a period T55 after time t54, the value of the power Pld of the load 4 becomes a value (Pld55) that is greater than the first threshold power Pth1 and smaller than Pld53.

[0145] In power conversion control example 5, first, during period T51, the value of the power Pld of the load 4 (Pld51) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T51, power is supplied from the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) to the load 4 and second vehicle battery 6a (sub-vehicle battery).

[0146] 10, during period T51, the value of the power P2 of the second in-vehicle battery 6a is set to a value (-Pj2) that is the negative of the maximum charging power Pj2 of the second in-vehicle battery 6a. Meanwhile, during period T51, the value of the power P1 of the first in-vehicle battery 5a is set to a value (P151) that is greater than 0 and less than the maximum discharging power Ph1, and the value of the power P3 of the third in-vehicle battery 7a is set to a value (P351) that is greater than 0 and less than the maximum discharging power Ph3. In this case, ignoring power conversion efficiency, the value of the power P1 of the first vehicle battery 5a (P151) and the value of the power P3 of the third vehicle battery 7a (P351) are set so that the output (discharge) power (P151+P351) from the main vehicle battery group is roughly the same as the sum of the power consumption (Pld51) at the load 4 and the maximum charging power Pj2 of the second vehicle battery 6a. Note that the proportion (split proportion) of the discharge power shared by each of the first vehicle battery 5a and the third vehicle battery 7a can be set arbitrarily, but may also be set according to the state of charge, remaining energy, capacity, etc. of each of the first vehicle battery 5a and the third vehicle battery 7a.

[0147] Next, during period T52, the value of the power Pld of the load 4 (Pld52) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, even during period T52, power is supplied from the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) to the load 4 and the second vehicle battery 6a (sub-vehicle battery).

[0148] In the example shown in FIG. 10 , during period T52, the value of the power Pld of the load 4 (Pld52) is greater than the value of the power Pld of the load 4 (Pld51) during period T51 and is close to the first threshold power Pth1. Therefore, during period T52, the value of the power P1 of the first vehicle battery 5a (main vehicle battery) is set to the maximum discharge power Ph1, and the value of the power P3 of the third vehicle battery 7a (main vehicle battery) is also set to the maximum discharge power Ph3. Furthermore, at this time, the discharge power output from the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) is greater than the power Pld of the load 4 (Pld52), so even if power is supplied from the main vehicle battery group to the load 4, there is surplus discharge power. Therefore, during period T52, the surplus discharge power is supplied to the second vehicle battery 6a (sub-vehicle battery), and the second vehicle battery 6a is charged. As a result, during period T52, the value of the power P2 of the second vehicle battery 6a becomes a value (P252) that is less than 0 and greater than the negative value of the maximum charging power Pj2 of the second vehicle battery 6a. In other words, the charging power of the second vehicle battery 6a during period T52 becomes smaller than the charging power of the second vehicle battery 6a during period T51.

[0149] Next, during period T53, the value of the power Pld of the load 4 (Pld53) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T53, power is supplied to the load 4 from both the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) and the second vehicle battery 6a (sub-vehicle battery).

[0150] 10, during period T53, the value of power P1 of the first vehicle battery 5a (main vehicle battery) is maintained at the maximum discharge power Ph1, and the value of power P3 of the third vehicle battery 7a (main vehicle battery) is also maintained at the maximum discharge power Ph3. Meanwhile, during period T53, in order to continue backup power supply to the load 4, the second vehicle battery 6a (sub-vehicle battery) supplies the load 4 with power that is insufficient for the power supplied from the main vehicle batteries (Ph1+Ph3). Therefore, during period T53, the value of power P2 of the second vehicle battery 6a is set to a value (P253) that is greater than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a.

[0151] Next, during period T54, the value of the power Pld of the load 4 (Pld54) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T54, power is supplied from the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) to the load 4 and second vehicle battery 6a.

[0152] In the example shown in FIG. 10, during period T54, the value of the power Pld of the load 4 (Pld54) is greater than the value of the power Pld of the load 4 (Pld51) during period T51 and is close to the first threshold power Pth1. Therefore, during period T54, the value of the power P1 of the first vehicle battery 5a (main vehicle battery) is maintained at the maximum discharge power Ph1, and the value of the power P3 of the third vehicle battery 7a (main vehicle battery) is also maintained at the maximum discharge power Ph3. Furthermore, at this time, the discharge power output from the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) is greater than the power Pld of the load 4 (Pld54), so even if power is supplied from the main vehicle battery group to the load 4, there is surplus discharge power. Therefore, during period T54, the surplus discharge power is supplied to the second vehicle battery 6a (sub-vehicle battery), and the second vehicle battery 6a is charged. As a result, during period T54, the value of the power P2 of the second vehicle battery 6a becomes a value (P254) that is less than 0 and greater than the negative value of the maximum charging power Pj2 of the second vehicle battery 6a. Note that the power consumption (Pld54) of the load 4 during period T54 is less than the power consumption (Pld52) of the load 4 during period T52, so the absolute value (charging power) of the value of the power P2 (P254) of the second vehicle battery 6a during period T54 becomes greater than the absolute value (charging power) of the value of the power P2 (P252) of the second vehicle battery 6a during period T52.

[0153] That is, in power conversion control example 5, when the power consumption of the load 4 decreases during operation (execution) of the first operation mode, and the value of the power Pld of the load 4 becomes smaller than the first threshold power Pth1, the operation mode of the power conversion system 1 switches to the second operation mode. As a result, power supply from the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) to the load 4 continues, but the operation mode of the second vehicle battery 6a (sub-vehicle battery) switches from discharging to charging.

[0154] During period T55, the value of the power Pld of the load 4 (Pld55) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T55, power is supplied to the load 4 from both the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) and the second vehicle battery 6a.

[0155] 10, during period T55, the value of power P1 of the first vehicle battery 5a (main vehicle battery) is maintained at the maximum discharge power Ph1, and the value of power P3 of the third vehicle battery 7a (main vehicle battery) is also maintained at the maximum discharge power Ph3. Meanwhile, during period T55, in order to continue backup power supply to the load 4, the second vehicle battery 6a (sub-vehicle battery) supplies power to the load 4 that is insufficient with the power supplied from the main vehicle batteries (Ph1+Ph3). Therefore, the value of power P2 of the second vehicle battery 6a is set to a value (P255) greater than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a. Furthermore, since the power consumption (Pld55) of the load 4 during period T55 is smaller than the power consumption (Pld53) of the load 4 during period T53, the value of the power P2 of the second vehicle battery 6a during period T55 (P255) is smaller than the value of the power P2 of the second vehicle battery 6a during period T53 (P253).

[0156] In power conversion control example 5, after a power outage occurs, the discharge operation of the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) and the charge / discharge operation of the second vehicle battery 6a (sub-vehicle battery) are controlled in the manner described above in response to fluctuations in the power Pld (power consumption) of the load 4.

[0157] In power conversion control example 5, as described above, similar to power conversion control example 1, when the value of the power Pld of the load 4 is smaller than the first threshold power Pth1, the second operating mode is activated. That is, power is supplied from the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) with a sufficient state of charge to the second vehicle battery 6a (sub-vehicle battery) with a sufficient state of charge, and the second vehicle battery 6a is charged. Therefore, in power conversion control example 5, similar to power conversion control example 1, the duration of backup power supply to the load 4 can be extended.

[0158] (6) Power conversion control example 6 Next, referring to Fig. 11, a sixth example of power conversion control in the power conversion system 1 performed when the commercial power supply 2 experiences a power outage will be described. As with the fifth example of power conversion control, the sixth example of power conversion control will be described in terms of a case where the first, second, and third vehicle batteries 5a, 6a, and 7a are connected to the power conversion system 1 during a power outage. Furthermore, as with the second example of power conversion control, the sixth example of power conversion control will be described in terms of a case where the load 4 includes a load (equipment) that generates regenerative power.

[0159] In power conversion control example 6, the state of charge of each of the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a during a power outage is the same as the state of charge described in Figure 9 (power conversion control example 5). That is, in power conversion control example 6, as in power conversion control example 5, the first vehicle battery 5a and the third vehicle battery 7a serve as the main vehicle batteries (part of the vehicle batteries), and the second vehicle battery 6a serves as the sub-vehicle battery (the other part of the vehicle batteries). Therefore, in this example, ignoring power conversion efficiency, the maximum discharge power of the main vehicle battery group, i.e., the sum of the maximum discharge power Ph1 of the first vehicle battery 5a and the maximum discharge power Ph3 of the third vehicle battery 7a, can be set as the first threshold power Pth1 (≈Ph1 + Ph3) for the power Pld of the load 4. Furthermore, in this example, if power conversion efficiency is ignored, the maximum charging power Pj2 of the second vehicle-mounted battery 6a can be set roughly as the second threshold power Pth2 (≈Pj2) of the power Pld of the load 4.

[0160] In power conversion control example 6, if the power Pld of the load 4 is greater than the first threshold power Pth1 during the power consumption period of the load 4, the power conversion system 1 operates in the first operation mode described above. On the other hand, if the power Pld of the load 4 is less than the first threshold power Pth1 during the power consumption period of the load 4, the power conversion system 1 operates in the second operation mode described above.

[0161] Furthermore, in power conversion control example 6, if the regenerated power from the load 4 (absolute value of Pld) is smaller than the second threshold power Pth2 during the power regeneration period of the load 4, the power conversion system 1 operates in the above-mentioned third operation mode. On the other hand, if the regenerated power from the load 4 is larger than the second threshold power Pth2 during the power regeneration period of the load 4, the power conversion system 1 operates in the above-mentioned fourth operation mode.

[0162] Fig. 11 is a diagram showing the time change characteristics of the power Pld of the load 4, the power P1 of the first vehicle battery 5a, the power P2 of the second vehicle battery 6a, and the power P3 of the third vehicle battery 7a after a power outage occurs in power conversion control example 6. Power conversion control example 6 shown in Fig. 11 explains an example in which the value of the power Pld (power consumption and regenerative power) of the load 4 changes over time after a power outage occurs as follows:

[0163] First, after a power outage occurs, during a period T61 from time t60 to t61, the value of the power Pld of the load 4 becomes greater than 0 and less than the first threshold power Pth1 (Pld61), as shown in the time-varying characteristics of the power Pld of the load 4 in Figure 11. Next, the power Pld of the load 4 increases, and during a period T62 from time t61 to t62, the value of the power Pld of the load 4 becomes greater than Pld61 and less than the first threshold power Pth1 (Pld62). Next, the power Pld of the load 4 increases, and during a period T63 from time t62 to t63, the value of the power Pld of the load 4 becomes greater than the first threshold power Pth1 (Pld63). Next, the power Pld of the load 4 decreases, and during a period T64 from time t63 to t64, the value of the power Pld of the load 4 becomes less than 0 and greater than the negative value of the second threshold power Pth2 (Pld64). Next, the power Pld of the load 4 decreases, and during a period T65 from time t64 to t65, the value of the power Pld of the load 4 becomes a value (Pld65) that is smaller than the negative value of the second threshold power Pth2. Next, the power Pld of the load 4 increases, and during a period T66 after time t65, the value of the power Pld of the load 4 becomes a value (Pld66) that is larger than the first threshold power Pth1.

[0164] 11, periods T64 and T65 are power regeneration periods, during which power is supplied from the load 4 to the power conversion system 1 (on-board battery side). Other periods are power consumption periods, during which power is supplied from the power conversion system 1 to the load 4.

[0165] In power conversion control example 6, first, during period T61 (power consumption period), the value (Pld61) of the power Pld of the load 4 is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T61, power is supplied from the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) to the load 4 and second vehicle battery 6a (sub-vehicle battery).

[0166] 11, during period T61, the power P2 value of the second vehicle battery 6a (sub-vehicle battery) is set to a value (-Pj2) that is the negative of the maximum charging power Pj2 of the second vehicle battery 6a. Meanwhile, during period T61, the power P1 value of the first vehicle battery 5a (main vehicle battery) is set to a value (P161) that is greater than 0 and less than the maximum discharging power Ph1, and the power P3 value of the third vehicle battery 7a (main vehicle battery) is set to a value (P361) that is greater than 0 and less than the maximum discharging power Ph3. In this case, ignoring power conversion efficiency, the value of the power P1 of the first vehicle battery 5a (P161) and the value of the power P3 of the third vehicle battery 7a (P361) are set so that the output (discharge) power (P161+P361) from the main vehicle battery group is roughly the same as the sum of the power consumption (Pld61) at the load 4 and the maximum charging power Pj2 of the second vehicle battery 6a. Note that the proportion (split proportion) of the discharge power shared by each of the first vehicle battery 5a and the third vehicle battery 7a can be set arbitrarily, but may also be set according to the state of charge, remaining energy, capacity, etc. of each of the first vehicle battery 5a and the third vehicle battery 7a.

[0167] Next, during period T62 (power consumption period), the value of the power Pld of the load 4 (Pld62) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, even during period T62, power is supplied from the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) to the load 4 and second vehicle battery 6a (sub-vehicle battery).

[0168] In the example shown in FIG. 11 , during period T62, the value of the power Pld of the load 4 (Pld62) is greater than the value of the power Pld of the load 4 (Pld61) during period T61 and is close to the first threshold power Pth1. Therefore, during period T62, the value of the power P1 of the first vehicle battery 5a (main vehicle battery) is set to the maximum discharge power Ph1, and the value of the power P3 of the third vehicle battery 7a (main vehicle battery) is also set to the maximum discharge power Ph3. Furthermore, at this time, because the discharge power output from the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) is greater than the power Pld of the load 4 (Pld62), there is surplus discharge power even when power is supplied from the main vehicle battery group to the load 4. Therefore, during period T62, the surplus discharge power is supplied to the second vehicle battery 6a (sub-vehicle battery), and the second vehicle battery 6a is charged. As a result, during period T62, the value of the power P2 of the second vehicle battery 6a becomes a value (P262) that is less than 0 and greater than the negative value of the maximum charging power Pj2 of the second vehicle battery 6a. In other words, the charging power of the second vehicle battery 6a during period T62 becomes smaller than the charging power of the second vehicle battery 6a during period T61.

[0169] Next, during period T63 (power consumption period), the value of the power Pld of the load 4 (Pld63) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T63, power is supplied to the load 4 from both the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) and the second vehicle battery 6a (sub-vehicle battery).

[0170] 11, during period T63, the value of power P1 of the first vehicle battery 5a (main vehicle battery) is maintained at the maximum discharge power Ph1, and the value of power P3 of the third vehicle battery 7a (main vehicle battery) is also maintained at the maximum discharge power Ph3. Meanwhile, during period T63, in order to continue backup power supply to the load 4, the second vehicle battery 6a (sub-vehicle battery) supplies power to the load 4 that is insufficient with the power supplied from the main vehicle batteries (Ph1+Ph3). Therefore, during period T63, the value of power P2 of the second vehicle battery 6a is set to a value (P263) greater than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a.

[0171] Next, during period T64 (power regeneration period), the power value Pld of the load 4 (Pld64) is greater than the negative value of the second threshold power Pth2, so the power conversion system 1 operates in the third operating mode. Therefore, during period T64, power is supplied to the second vehicle battery 6a (sub-vehicle battery) from both the load 4 and the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a), and the second vehicle battery 6a is charged.

[0172] 11, during period T64, the value of the power P2 of the second in-vehicle battery 6a is set to a value (-Pj2) that is negative of the maximum charge power Pj2. Meanwhile, during period T64, the value of the power P1 of the first in-vehicle battery 5a is set to a value (P164) that is greater than 0 and less than the maximum discharge power Ph1 of the first in-vehicle battery 5a, and the value of the power P1 of the third in-vehicle battery 7a is set to a value (P364) that is greater than 0 and less than the maximum discharge power Ph3 of the third in-vehicle battery 7a. At this time, the value of the power P1 of the first vehicle battery 5a (P164) and the value of the power P3 of the third vehicle battery 7a (P364) are set so that the second vehicle battery 6a is supplied with its maximum charging power Pj2 from both the load 4 and the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a), i.e., so that the second vehicle battery 6a is charged with the maximum charging power Pj2. Note that at this time, the proportion of discharge power shared by the first vehicle battery 5a and the third vehicle battery 7a (split proportion) can be set arbitrarily, but may also be set according to the state of charge, remaining energy, capacity, etc. of each of the first vehicle battery 5a and the third vehicle battery 7a.

[0173] Next, during period T65 (power regeneration period), the value of the power value Pld of the load 4 (Pld65) is smaller than the negative value of the second threshold power Pth2, so the power conversion system 1 operates in the fourth operating mode. Therefore, during period T65, power is supplied from the load 4 to the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) and the second vehicle battery 6a (sub-vehicle battery), and all vehicle batteries are charged.

[0174] 11, during period T65, the value of the power P2 of the second vehicle battery 6a is maintained at a value (-Pj2) that is negative of the maximum charging power Pj2. At this time, the regenerative power output from the load 4 is greater than the maximum charging power Pj2 of the second vehicle battery 6a, so even if the maximum charging power Pj2 is supplied from the load 4 to the second vehicle battery 6a, there is surplus regenerative power. Therefore, during period T65, the surplus regenerative power is supplied to the main vehicle battery group (the first vehicle battery 5a and the third vehicle battery 7a), and the first vehicle battery 5a and the third vehicle battery 7a are charged. As a result, during period T65, the value of the power P1 of the first in-vehicle battery 5a becomes a value (P165) that is less than 0 and greater than the negative value of the maximum charging power Pj1 of the first in-vehicle battery 5a, and the value of the power P3 of the third in-vehicle battery 7a becomes a value (P365) that is less than 0 and greater than the negative value of the maximum charging power Pj3 of the third in-vehicle battery 7a. Note that the ratio (split ratio) of the charging power supplied to the first in-vehicle battery 5a and the third in-vehicle battery 7a can be set arbitrarily, but may also be set according to the respective state of charge, remaining energy, and capacity of the first in-vehicle battery 5a and the third in-vehicle battery 7a, for example.

[0175] That is, in power conversion control example 6, when the power (regenerative power) output from the load 4 increases during operation (execution) of the third operation mode, and the absolute value of the power Pld of the load 4 becomes larger than the second threshold power Pth2, the operation mode of the power conversion system 1 switches to the fourth operation mode. As a result, power supply from the load 4 to the second vehicle battery 6a (sub-vehicle battery) continues, but the operation modes of the first vehicle battery 5a (main vehicle battery) and the third vehicle battery 7a (main vehicle battery) switch from discharging to charging.

[0176] During period T66 (power consumption period), the value of the power Pld of the load 4 (Pld66) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T66, power is supplied to the load 4 from both the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) and the second vehicle battery 6a (sub-vehicle battery).

[0177] 11, during period T66, the value of the power P1 of the first vehicle battery 5a (main vehicle battery) is set to the maximum discharge power Ph1, and the value of the power P3 of the third vehicle battery 7a (main vehicle battery) is also set to the maximum discharge power Ph3. Meanwhile, during period T66, in order to continue backup power supply to the load 4, the second vehicle battery 6a (sub-vehicle battery) supplies the load 4 with power that is insufficient beyond the power supply (Ph1+Ph3) from the main vehicle battery group. Therefore, during period T66, the value of the power P2 of the second vehicle battery 6a is set to a value (P266) that is greater than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a.

[0178] In power conversion control example 6, after a power outage occurs, the charging / discharging operation of the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) and the charging / discharging operation of the second vehicle battery 6a (sub-vehicle battery) are controlled in the manner described above in response to fluctuations in the power Pld (consumed / regenerated power) of the load 4.

[0179] In power conversion control example 6, as described above, similar to power conversion control example 5, when the value of the power Pld of the load 4 is less than the first threshold power Pth1 during the power consumption period of the load 4, the second operating mode is activated. That is, power is supplied from the main vehicle batteries (first vehicle battery 5a and third vehicle battery 7a) that have a sufficient state of charge to the second vehicle battery 6a (sub-vehicle battery) that has a limited state of charge, and the second vehicle battery 6a is charged. Therefore, in power conversion control example 6, similar to power conversion control example 1, the duration of backup power supply to the load 4 can be extended.

[0180] Furthermore, in power conversion control example 6, during the power regeneration period of the load 4, the second vehicle battery 6a (sub-vehicle battery) or both the main vehicle battery group (first vehicle battery 5a and third vehicle battery 7a) and the second vehicle battery 6a are charged with regenerative power output from the load 4. Therefore, in power conversion control example 6, the duration of backup power supply to the load 4 can be further extended compared to power conversion control example 5.

[0181] (7) Power conversion control example 7 Next, referring to Figures 12 and 13, a seventh example of power conversion control in the power conversion system 1 that is performed when the commercial power supply 2 experiences a power outage will be described. As with the fifth example of power conversion control, the seventh example of power conversion control will be described assuming that a first electric vehicle 5, a second electric vehicle 6, and a third electric vehicle 7 are present at the time of the power outage, that is, a first on-board battery 5a, a second on-board battery 6a, and a third on-board battery 7a are connected to the power conversion system 1. As with the first example of power conversion control, the seventh example of power conversion control will be described assuming that the load 4 does not include a load (equipment) that generates regenerative power.

[0182] Fig. 12 is a diagram showing the state of charge of each vehicle-mounted battery in power conversion control example 7. In power conversion control example 7, as shown in Fig. 12, the SOC value S1 of the first vehicle-mounted battery 5a is greater than the first threshold value Sth1 and less than 1, the SOC value S2 of the second vehicle-mounted battery 6a is less than the second threshold value Sth2 and greater than the third threshold value Sth3, and the SOC value S3 of the third vehicle-mounted battery 7a is less than the second threshold value Sth2 and greater than the third threshold value Sth3.

[0183] In this case, the main vehicle battery (part of the vehicle batteries) with a charge state that is sufficiently greater than the third threshold Sth3 (lower discharge limit) becomes the first vehicle battery 5a, and the sub vehicle batteries (other part of the vehicle batteries) with a charge state that is not sufficient to be greater than the third threshold Sth3 become the second vehicle battery 6a and the third vehicle battery 7a. Therefore, in this example, ignoring power conversion efficiency, the maximum discharge power Ph1 of the first vehicle battery 5a can be set roughly as the first threshold power Pth1 (≈Ph1) of the power Pld of the load 4.

[0184] In power conversion control example 7, when the power Pld of the load 4 is greater than the first threshold power Pth1, the power conversion system 1 operates in the first operation mode described above. On the other hand, when the power Pld of the load 4 is less than the first threshold power Pth1, the power conversion system 1 operates in the second operation mode described above.

[0185] Fig. 13 is a diagram showing the time change characteristics of the power Pld of the load 4, the power P1 of the first vehicle battery 5a, the power P2 of the second vehicle battery 6a, and the power P3 of the third vehicle battery 7a after a power outage occurs in power conversion control example 7. Power conversion control example 7 shown in Fig. 13 explains an example in which the value of the power Pld (power consumption) of the load 4 changes over time after a power outage occurs as follows:

[0186] First, after a power outage occurs, during a period T71 from time t70 to t71, the value of the power Pld of the load 4 becomes a value (Pld71) that is greater than 0 and less than the first threshold power Pth1, as shown in the time-varying characteristics of the power Pld of the load 4 in Figure 13. Next, the power Pld of the load 4 increases, and during a period T72 from time t71 to t72, the value of the power Pld of the load 4 becomes a value (Pld72) that is greater than the first threshold power Pth1. Next, the power Pld of the load 4 decreases, and during a period T73 from time t72 to t73, the value of the power Pld of the load 4 becomes a value (Pld73) that is greater than 0 and less than the first threshold power Pth1. Next, the power Pld of the load 4 increases, and during a period T74 from time t73 to t74, the value of the power Pld of the load 4 becomes a value (Pld74) that is greater than the first threshold power Pth1. Next, the power Pld of the load 4 decreases, and in a period T75 after time t74, the value of the power Pld of the load 4 becomes a value (Pld75) that is greater than 0 and less than the first threshold power Pth1.

[0187] In power conversion control example 7, the value of the power Pld of the load 4 in period T71 (Pld71), the value of the power Pld of the load 4 in period T73 (Pld73), and the value of the power Pld of the load 4 in period T75 (Pld75) are assumed to be approximately the same. Also, in power conversion control example 7, the value of the power Pld of the load 4 in period T72 (Pld72) and the value of the power Pld of the load 4 in period T74 (Pld74) are assumed to be approximately the same.

[0188] In power conversion control example 7, first, during period T71, the value of the power Pld of the load 4 (Pld71) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T71, power is supplied from the first vehicle battery 5a (main vehicle battery) to the load 4 and the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a).

[0189] 13, during period T71, the power P1 value of the first in-vehicle battery 5a is set to the maximum discharge power Ph1. Meanwhile, during period T71, the power P2 value of the second in-vehicle battery 6a (sub-in-vehicle battery) is a value (P271) that is less than 0 and greater than the negative value of the maximum charge power Pj2 of the second in-vehicle battery 6a, and the power P3 value of the third in-vehicle battery 7a (sub-in-vehicle battery) is a value (P371) that is less than 0 and greater than the negative value of the maximum charge power Pj3 of the third in-vehicle battery 7a. In this case, the value of the power P2 (P271) of the second in-vehicle battery 6a and the value of the power P3 (P371) of the third in-vehicle battery 7a are set so that, ignoring power conversion efficiency, the power output (discharged) from the first in-vehicle battery 5a (maximum discharge power Ph1) is roughly equal to the sum of the power consumed by the load 4 (Pld71) and the power supplied to the sub-in-vehicle battery group (second in-vehicle battery 6a and third in-vehicle battery 7a) (absolute value of P271 + absolute value of P371). Note that the ratio (split ratio) of the charging power supplied from the first in-vehicle battery 5a to each of the second in-vehicle battery 6a and third in-vehicle battery 7a can be set arbitrarily, but may also be set according to, for example, the state of charge, remaining energy, and capacity of each of the second in-vehicle battery 6a and third in-vehicle battery 7a.

[0190] Next, during period T72, the value of the power Pld of the load 4 (Pld72) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T72, power is supplied to the load 4 from both the first vehicle battery 5a (main vehicle battery) and the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a).

[0191] 13, during period T72, the value of the power P1 of the first vehicle battery 5a is maintained at the maximum discharge power Ph1. Meanwhile, during period T72, in order to continue backup power supply to the load 4, the power that is insufficient due to the power (Ph1) supplied from the first vehicle battery 5a (main vehicle battery) alone is supplied from the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a) to the load 4. Therefore, during period T72, the value of the power P2 of the second vehicle battery 6a is set to a value (P272) greater than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a, and the value of the power P3 of the third vehicle battery 7a is set to a value (P372) greater than 0 and less than the maximum discharge power Ph3 of the third vehicle battery 7a. In this case, the ratio (split ratio) of the discharge power shared by the second vehicle battery 6a and the third vehicle battery 7a can be set arbitrarily, but may also be set, for example, according to the state of charge, remaining energy, capacity, etc. of each of the second vehicle battery 6a and the third vehicle battery 7a.

[0192] Next, during period T73, the value of the power Pld of the load 4 (Pld73) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T73, power is supplied from the first vehicle battery 5a (main vehicle battery) to the load 4 and the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a).

[0193] 13, during period T73, the power P1 of the first in-vehicle battery 5a is maintained at the maximum discharge power Ph1. Meanwhile, during period T73, the power P2 of the second in-vehicle battery 6a (sub-in-vehicle battery) becomes a value (P273) that is less than 0 and greater than the negative value of the maximum charge power Pj2 of the second in-vehicle battery 6a, and the power P3 of the third in-vehicle battery 7a (sub-in-vehicle battery) becomes a value (P373) that is less than 0 and greater than the negative value of the maximum charge power Pj3 of the third in-vehicle battery 7a. In this case, the value of the power P2 (P273) of the second in-vehicle battery 6a and the value of the power P3 (P373) of the third in-vehicle battery 7a are set so that, ignoring power conversion efficiency, the power output (discharged) from the first in-vehicle battery 5a (maximum discharge power Ph1) is roughly equal to the sum of the power consumed by the load 4 (Pld73) and the power supplied to the sub-in-vehicle battery group (second in-vehicle battery 6a and third in-vehicle battery 7a) (absolute value of P273 + absolute value of P373). Note that the ratio (split ratio) of the charging power supplied from the first in-vehicle battery 5a to each of the second in-vehicle battery 6a and third in-vehicle battery 7a can be set arbitrarily, but may also be set according to, for example, the state of charge, remaining energy, and capacity of each of the second in-vehicle battery 6a and third in-vehicle battery 7a.

[0194] That is, in power conversion control example 7, when the power consumption of the load 4 decreases during operation (execution) of the first operation mode, and the value of the power Pld of the load 4 becomes smaller than the first threshold power Pth1, the operation mode of the power conversion system 1 switches to the second operation mode. As a result, the power supply from the main vehicle battery (first vehicle battery 5a) to the load 4 continues, but the operation modes of the second vehicle battery 6a (sub-vehicle battery) and the third vehicle battery 7a (sub-vehicle battery) switch from discharging to charging.

[0195] Next, during period T74, the value of the power Pld of the load 4 (Pld74) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T74, power is supplied to the load 4 from both the first vehicle battery 5a (main vehicle battery) and the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a).

[0196] 13, during period T74, the value of the power P1 of the first vehicle battery 5a is maintained at the maximum discharge power Ph1. Meanwhile, during period T74, in order to continue backup power supply to the load 4, the power that is insufficient to be supplied from the first vehicle battery 5a (main vehicle battery) alone (Ph1) is supplied from the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a) to the load 4. Therefore, during period T74, the value of the power P2 of the second vehicle battery 6a is set to a value (P274) greater than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a, and the value of the power P3 of the third vehicle battery 7a is set to a value (P374) greater than 0 and less than the maximum discharge power Ph3 of the third vehicle battery 7a. In this case, the ratio (split ratio) of the discharge power shared by the second vehicle battery 6a and the third vehicle battery 7a can be set arbitrarily, but may also be set, for example, according to the state of charge, remaining energy, capacity, etc. of each of the second vehicle battery 6a and the third vehicle battery 7a.

[0197] During period T75, the value of the power Pld of the load 4 (Pld75) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T75, power is supplied from the first vehicle battery 5a (main vehicle battery) to the load 4 and the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a).

[0198] 13, during period T75, the power P1 of the first in-vehicle battery 5a is maintained at the maximum discharge power Ph1. Meanwhile, during period T75, the power P2 of the second in-vehicle battery 6a (sub-in-vehicle battery) becomes a value (P275) that is less than 0 and greater than the negative value of the maximum charge power Pj2 of the second in-vehicle battery 6a, and the power P3 of the third in-vehicle battery 7a (sub-in-vehicle battery) becomes a value (P375) that is less than 0 and greater than the negative value of the maximum charge power Pj3 of the third in-vehicle battery 7a. In this case, the value of the power P2 (P275) of the second in-vehicle battery 6a and the value of the power P3 (P375) of the third in-vehicle battery 7a are set so that, ignoring power conversion efficiency, the power output (discharged) from the first in-vehicle battery 5a (maximum discharge power Ph1) is roughly equal to the sum of the power consumed by the load 4 (Pld75) and the power supplied to the sub-in-vehicle battery group (second in-vehicle battery 6a and third in-vehicle battery 7a) (absolute value of P275 + absolute value of P375). Note that the ratio (split ratio) of the charging power supplied from the first in-vehicle battery 5a to each of the second in-vehicle battery 6a and third in-vehicle battery 7a can be set arbitrarily, but may also be set according to, for example, the state of charge, remaining energy, and capacity of each of the second in-vehicle battery 6a and third in-vehicle battery 7a.

[0199] In power conversion control example 7, after a power outage occurs, the discharge operation of the first vehicle battery 5a (main vehicle battery) and the charge / discharge operation of the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a) are controlled in the manner described above in response to fluctuations in the power Pld (power consumption) of the load 4.

[0200] In power conversion control example 7, as described above, similar to power conversion control example 1, when the value of the power Pld of the load 4 is smaller than the first threshold power Pth1, the second operating mode is activated. That is, power is supplied from the first vehicle battery 5a (main vehicle battery) that has a sufficient charge margin to the sub-vehicle batteries (second vehicle battery 6a and third vehicle battery 7a) that have a limited charge margin, and the second vehicle battery 6a and third vehicle battery 7a are charged. Therefore, in power conversion control example 7, similar to power conversion control example 1, the duration of backup power supply to the load 4 can be extended.

[0201] (8) Power conversion control example 8 Next, referring to Fig. 14, a description will be given of power conversion control example 8 in the power conversion system 1 that is performed when the commercial power supply 2 experiences a power outage. Note that, in power conversion control example 8, similar to power conversion control example 7 above, a description will be given of a case where the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a are connected to the power conversion system 1 during a power outage. Furthermore, in power conversion control example 8, similar to power conversion control example 2 above, a description will be given of a case where the load 4 includes a load (equipment) that generates regenerative power.

[0202] Furthermore, in power conversion control example 8, the state of charge of each of the first vehicle battery 5a, second vehicle battery 6a, and third vehicle battery 7a during a power outage is the same as the state of charge described in Figure 12 (power conversion control example 7). That is, in power conversion control example 8, as in power conversion control example 7, the first vehicle battery 5a serves as the main vehicle battery (part of the vehicle batteries), and the second vehicle battery 6a and third vehicle battery 7a serve as sub-vehicle batteries (other part of the vehicle batteries). Therefore, in this example, ignoring power conversion efficiency, the maximum discharge power Ph1 of the first vehicle battery 5a can be set roughly as the first threshold power Pth1 (≈Ph1) of the power Pld of the load 4. Furthermore, in this example, if power conversion efficiency is ignored, the maximum charging power in the sub-vehicle battery group, i.e., the sum of the maximum charging power Pj2 of the second vehicle battery 6a and the maximum charging power Pj3 of the third vehicle battery 7a, can be set as the second threshold power Pth2 (≒Pj2+Pj3) of the power Pld of the load 4.

[0203] In power conversion control example 8, if the power Pld of the load 4 is greater than the first threshold power Pth1 during the power consumption period of the load 4, the power conversion system 1 operates in the above-mentioned first operation mode. On the other hand, if the power Pld of the load 4 is less than the first threshold power Pth1 during the power consumption period of the load 4, the power conversion system 1 operates in the above-mentioned second operation mode.

[0204] Furthermore, in power conversion control example 8, if the regenerated power from the load 4 (absolute value of Pld) is smaller than the second threshold power Pth2 during the power regeneration period of the load 4, the power conversion system 1 operates in the above-mentioned third operation mode. On the other hand, if the regenerated power from the load 4 is larger than the second threshold power Pth2 during the power regeneration period of the load 4, the power conversion system 1 operates in the above-mentioned fourth operation mode.

[0205] Fig. 14 is a diagram showing the time change characteristics of the power Pld of the load 4, the power P1 of the first vehicle battery 5a, the power P2 of the second vehicle battery 6a, and the power P3 of the third vehicle battery 7a after a power outage occurs in power conversion control example 8. Power conversion control example 8 shown in Fig. 14 explains an example in which the value of the power Pld (power consumption and regenerative power) of the load 4 changes over time after a power outage occurs as follows:

[0206] First, after a power outage occurs, during a period T81 from time t80 to t81, the value of the power Pld of the load 4 becomes a value (Pld81) that is greater than 0 and less than the first threshold power Pth1, as shown in the time-varying characteristics of the power Pld of the load 4 in FIG. 14. Next, the power Pld of the load 4 increases, and during a period T82 from time t81 to t82, the value of the power Pld of the load 4 becomes a value (Pld82) that is greater than the first threshold power Pth1. Next, the power Pld of the load 4 decreases, and during a period T83 from time t82 to t83, the value of the power Pld of the load 4 becomes a value (Pld83) that is less than 0 and greater than the negative value of the second threshold power Pth2. Next, the power Pld of the load 4 decreases, and during a period T84 from time t83 to t84, the value of the power Pld of the load 4 becomes a value (Pld84) that is less than Pld83 and greater than the negative value of the second threshold power Pth2. Next, the power Pld of the load 4 decreases, and during a period T85 from time t84 to t85, the value of the power Pld of the load 4 becomes a value (Pld85) that is smaller than the negative value of the second threshold power Pth2. Next, the power Pld of the load 4 increases, and during a period T86 after time t85, the value of the power Pld of the load 4 becomes a value (Pld86) that is larger than the first threshold power Pth1.

[0207] 14, periods T83, T84, and T85 are power regeneration periods, during which power is supplied from the load 4 to the power conversion system 1 (on-board battery side). The other periods are power consumption periods, during which power is supplied from the power conversion system 1 to the load 4.

[0208] In power conversion control example 8, first, during period T81 (power consumption period), the value of the power Pld of the load 4 (Pld81) is smaller than the first threshold power Pth1, so the power conversion system 1 operates in the second operating mode. Therefore, during period T81, power is supplied from the first vehicle battery 5a (main vehicle battery) to the load 4 and the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a).

[0209] 14, during period T81, the power P1 value of the first in-vehicle battery 5a is set to the maximum discharge power Ph1. Meanwhile, during period T81, the power P2 value of the second in-vehicle battery 6a (sub-in-vehicle battery) becomes a value (P281) that is less than 0 and greater than the negative value of the maximum charge power Pj2 of the second in-vehicle battery 6a, and the power P3 value of the third in-vehicle battery 7a (sub-in-vehicle battery) becomes a value (P381) that is less than 0 and greater than the negative value of the maximum charge power Pj3 of the third in-vehicle battery 7a. In this case, the value of the power P2 (P281) of the second in-vehicle battery 6a and the value of the power P3 (P381) of the third in-vehicle battery 7a are set so that, ignoring power conversion efficiency, the power output (discharged) from the first in-vehicle battery 5a (maximum discharge power Ph1) is roughly equal to the sum of the power consumed by the load 4 (Pld81) and the power supplied to the sub-in-vehicle battery group (second in-vehicle battery 6a and third in-vehicle battery 7a) (absolute value of P281 + absolute value of P381). Note that the ratio (split ratio) of the charging power supplied from the first in-vehicle battery 5a to each of the second in-vehicle battery 6a and third in-vehicle battery 7a can be set arbitrarily, but may also be set according to, for example, the state of charge, remaining energy, and capacity of each of the second in-vehicle battery 6a and third in-vehicle battery 7a.

[0210] Next, during period T82, the value of the power Pld of the load 4 (Pld82) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T82, power is supplied to the load 4 from both the first vehicle battery 5a (main vehicle battery) and the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a).

[0211] 14, during period T82, the value of the power P1 of the first vehicle battery 5a is maintained at the maximum discharge power Ph1. Meanwhile, during period T82, in order to continue backup power supply to the load 4, the power that is insufficient for the power supply (Ph1) from the first vehicle battery 5a (main vehicle battery) alone is supplied to the load 4 from the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a). Therefore, during period T82, the value of the power P2 of the second vehicle battery 6a is set to a value (P282) greater than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a, and the value of the power P3 of the third vehicle battery 7a is set to a value (P382) greater than 0 and less than the maximum discharge power Ph3 of the third vehicle battery 7a. In this case, the ratio (split ratio) of the discharge power shared by the second vehicle battery 6a and the third vehicle battery 7a can be set arbitrarily, but may also be set, for example, according to the state of charge, remaining energy, capacity, etc. of each of the second vehicle battery 6a and the third vehicle battery 7a.

[0212] Next, during period T83 (power regeneration period), the value of the power value Pld of the load 4 (Pld83) is greater than the negative value of the second threshold power Pth2, so the power conversion system 1 operates in the third operating mode. Therefore, during period T83, power is supplied from both the load 4 and the first vehicle battery 5a (main vehicle battery) to the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a), and the second vehicle battery 6a and third vehicle battery 7a are charged.

[0213] 14, during period T63, the power P1 value of the first vehicle battery 5a (main vehicle battery) is maintained at the maximum discharge power Ph1. Meanwhile, during period T83, the power P2 value of the second vehicle battery 6a (sub-vehicle battery) is set to a value (P283) that is less than 0 and less than the negative value of the maximum charge power Pj2 of the second vehicle battery 6a, and the power P3 value of the third vehicle battery 7a (sub-vehicle battery) is set to a value (P383) that is less than 0 and less than the negative value of the maximum charge power Pj3 of the third vehicle battery 7a. In this case, if power conversion efficiency is ignored, the value of the power P2 (P283) of the second vehicle battery 6a and the value of the power P3 (P383) of the third vehicle battery 7a are set so that the power output from both the load 4 and the first vehicle battery 5a is roughly the same as the charging power (absolute value of P283 + absolute value of P383) of the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a). Note that the ratio (split ratio) of the charging power supplied to each of the second vehicle battery 6a and the third vehicle battery 7a can be set arbitrarily, but may also be set according to, for example, the state of charge, remaining energy, and capacity of each of the second vehicle battery 6a and the third vehicle battery 7a.

[0214] Next, during period T84 (power regeneration period), the value of the power value Pld of the load 4 (Pld84) is greater than the negative value of the second threshold power Pth2, so the power conversion system 1 operates in the third operating mode. Therefore, even during period T84, power is supplied from both the load 4 and the first vehicle battery 5a (main vehicle battery) to the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a), and the second vehicle battery 6a and third vehicle battery 7a are charged.

[0215] 14, during period T84, the regenerative power (Pld84) output from the load 4 is greater than Pld83 and is close to the second threshold power Pth2. Therefore, during period T84, the value of the power P2 of the second vehicle battery 6a (sub-vehicle battery) is set to the negative value (-Pj2) of the maximum charging power Pj2, and the value of the power P3 of the third vehicle battery 7a (sub-vehicle battery) is also set to the negative value (-Pj3) of the maximum charging power Pj3. Meanwhile, during period T84, the value of the power P1 of the first vehicle battery 5a is set to a value (Pl84) greater than 0 and less than the maximum discharging power Ph1 of the first vehicle battery 5a. At this time, the value of the power P1 (P184) of the first vehicle battery 5a is set so that maximum charging power is supplied to each of the second vehicle battery 6a and the third vehicle battery 7a from both the load 4 and the first vehicle battery 5a, i.e., so that each sub-vehicle battery is charged with maximum charging power.

[0216] Next, during period T85 (power regeneration period), the value of the power value Pld of the load 4 (Pld85) is smaller than the negative value of the second threshold power Pth2, so the power conversion system 1 operates in the fourth operating mode. Therefore, during period T85, power is supplied from the load 4 to the first vehicle battery 5a (main vehicle battery) and the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a), and all vehicle batteries are charged.

[0217] In the example shown in FIG. 14, during period T85, the value of power P2 of the second vehicle battery 6a (sub-vehicle battery) is maintained at a value (-Pj2) that is negative of the maximum charging power Pj2, and the value of power P3 of the third vehicle battery 7a (sub-vehicle battery) is maintained at a value (-Pj3) that is negative of the maximum charging power Pj3. Furthermore, since the regenerative power output from the load 4 at this time is greater than the sum of the maximum charging power Pj2 of the second vehicle battery 6a and the maximum charging power Pj3 of the third vehicle battery 7a, even if the load 4 supplies maximum charging power to each of the second vehicle battery 6a and the third vehicle battery 7a, there is surplus regenerative power. Therefore, during period T85, the surplus regenerative power is supplied to the first vehicle battery 5a (main vehicle battery), and the first vehicle battery 5a is charged. As a result, during the period T85, the value of the power P1 of the first vehicle battery 5a becomes a value (P185) that is smaller than 0 and larger than the negative value of the maximum charging power Pj1 of the first vehicle battery 5a.

[0218] That is, in power conversion control example 8, when the power (regenerative power) output from the load 4 increases during operation (execution) of the third operation mode, and the absolute value of the power Pld of the load 4 becomes larger than the second threshold power Pth2, the operation mode of the power conversion system 1 switches to the fourth operation mode. As a result, power supply from the load 4 to the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a) continues, but the operation mode of the first vehicle battery 5a (main vehicle battery) switches from discharging to charging.

[0219] During period T86 (power consumption period), the value of the power Pld of the load 4 (Pld86) is greater than the first threshold power Pth1, so the power conversion system 1 operates in the first operating mode. Therefore, during period T86, power is supplied to the load 4 from both the first vehicle battery 5a (main vehicle battery) and the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a).

[0220] 14, during period T86, the value of the power P1 of the first vehicle battery 5a is set to the maximum discharge power Ph1. Meanwhile, during period T86, in order to continue backup power supply to the load 4, the power supply (Ph1) from the first vehicle battery 5a (main vehicle battery) alone is insufficient, and the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a) supplies the load 4 with the power P2 that is insufficient from the power supply (Ph1) from the first vehicle battery 5a (main vehicle battery). Therefore, during period T86, the value of the power P2 of the second vehicle battery 6a is set to a value (P286) greater than 0 and less than the maximum discharge power Ph2 of the second vehicle battery 6a, and the value of the power P3 of the third vehicle battery 7a is set to a value (P386) greater than 0 and less than the maximum discharge power Ph3 of the third vehicle battery 7a. In this case, the ratio (split ratio) of the discharge power shared by the second vehicle battery 6a and the third vehicle battery 7a can be set arbitrarily, but may also be set, for example, according to the state of charge, remaining energy, capacity, etc. of each of the second vehicle battery 6a and the third vehicle battery 7a.

[0221] In power conversion control example 8, after a power outage occurs, the charge / discharge operation of the first vehicle battery 5a (main vehicle battery) and the charge / discharge operation of the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a) are controlled in the manner described above in response to fluctuations in the power Pld (consumed / regenerated power) of the load 4.

[0222] In power conversion control example 8, as described above, similar to power conversion control example 7, when the value of the power Pld of the load 4 is less than the first threshold power Pth1 during the power consumption period of the load 4, the second operating mode is activated. That is, power is supplied from the first vehicle battery 5a (main vehicle battery) that has a sufficient charge margin to the sub-vehicle batteries (second vehicle battery 6a and third vehicle battery 7a) that have a limited charge margin, and both the second vehicle battery 6a and the third vehicle battery 7a are charged. Therefore, in power conversion control example 8, similar to power conversion control example 7, the duration of backup power supply to the load 4 can be extended.

[0223] Furthermore, in power conversion control example 8, similar to power conversion control example 2 above, during the power regeneration period of the load 4, the sub-vehicle battery group (second vehicle battery 6a and third vehicle battery 7a) or both the first vehicle battery 5a (main vehicle battery) and the sub-vehicle battery group are charged with regenerative power output from the load 4. Therefore, in power conversion control example 8, the duration of backup power supply to the load 4 can be further extended compared to power conversion control example 7 above.

[0224] [effect] As described above, in the power conversion system 1 of this embodiment, when a power outage occurs, the multiple on-board batteries connected to the power conversion system 1 include a main on-board battery (main on-board battery group) that has a sufficient state of charge and a sub-on-board battery (sub-on-board battery group) that does not have a sufficient state of charge, and when the power consumption of the load 4 is less than a predetermined threshold power (the first threshold power Pth1 described above), the main on-board battery supplies power not only to the load 4 but also to the sub-on-board battery to charge the sub-on-board battery (sub-on-board battery group) (the second operation mode described above). Furthermore, in the case where the load 4 includes equipment with a regenerative function, the power conversion system 1 of this embodiment has a function (third and fourth operation modes) to supply power to the sub-on-board battery (sub-on-board battery group) or to both the main on-board battery (main on-board battery group) and the sub-on-board battery (sub-on-board battery group) using regenerative power output from the load 4 during the power regeneration period of the load 4 after the occurrence of a power outage.

[0225] Therefore, with the power conversion system 1 of this embodiment, even when backup power is supplied to the load 4 after a power outage, it is possible to prevent the charge state of the sub-vehicle battery from decreasing to the lower discharge limit, thereby extending the duration of backup power supply to the load 4. In other words, with the power conversion system 1 of this embodiment, when backup power is supplied to the load 4 (equipment) using on-board batteries of multiple vehicles during a power outage, it is possible to continue stably supplying power to the load 4 even if the multiple on-board batteries include an on-board battery that is not fully charged.

[0226] 2. Second embodiment In the first embodiment, a configuration example in which only a commercial power source 2 is connected to the power conversion system 1 has been described, but the present invention is not limited to this. In addition to the commercial power source, a renewable energy power source such as a solar cell may also be connected to the power conversion system. In the second embodiment, one such configuration example will be described.

[0227] [Power conversion system configuration] Fig. 15 is a schematic configuration diagram of a power conversion system according to a second embodiment of the present invention. In the power conversion system 20 of the second embodiment shown in Fig. 15, components similar to those of the power conversion system 1 of the first embodiment (see Fig. 1) are denoted by the same reference numerals, and description of these components will be omitted.

[0228] As shown in Fig. 15, the power conversion system 20 of this embodiment is connected not only to the commercial power supply 2 but also to a solar cell 8. The solar cell 8 can be configured using an existing solar cell, and operates by maximum power point tracking control to maximize the power generation in accordance with the solar radiation energy input to the solar cell 8 and the solar cell temperature. As is clear from a comparison of Fig. 15 with Fig. 1, the power conversion system 20 of this embodiment is configured such that a fourth DC / DC conversion unit 19 is further provided in the power conversion system 1 of the first embodiment (see Fig. 1).

[0229] One input / output terminal of the fourth DC / DC conversion unit 19 is connected to the DC power-side input / output terminals of the three AC / DC conversion units 13, 14, and 15, and the other input / output terminal of the fourth DC / DC conversion unit 19 is connected to the solar cell 8. The fourth DC / DC conversion unit 19 is also connected to the control unit 10, and converts the DC power input from the solar cell 8 into DC power of a specific value based on a control signal input from the control unit 10. That is, in the power conversion system 20, during normal operation and during a power outage of the commercial power supply 2, the first DC / DC conversion unit 16, the second DC / DC conversion unit 17, and the third DC / DC conversion unit 18 control the charge / discharge power of the first vehicle-mounted battery 5a, the second vehicle-mounted battery 6a, and the third vehicle-mounted battery 7a, respectively, and the fourth DC / DC conversion unit 19 controls the power generated by the solar cell 8.

[0230] [Outline of power conversion operation in a power conversion system] (normal times) In the power conversion system 20 of this embodiment, during normal times when the commercial power source 2 is not experiencing a power outage, the control unit 10 turns on the first relay 11 and turns off the second relay 12, and switches the connection of the power supply path switch 3 to the commercial power source 2 side. During normal times, the power conversion system 20 performs the following power conversion between the commercial power source 2 and each of the first vehicle battery 5a, the second vehicle battery 6a, the third vehicle battery 7a, and the solar cell 8 under the control of the control unit 10.

[0231] Under normal circumstances, first, the three AC / DC converters 13 to 15 convert AC power input from the commercial power supply 2 into DC power. Furthermore, the fourth DC / DC converter 19 converts DC power input from the solar cell 8 into DC power of a specific value.

[0232] Next, the first DC / DC conversion unit 16, the second DC / DC conversion unit 17, and the third DC / DC conversion unit 18 each convert the DC power converted by the three AC / DC conversion units 13 to 15 and the fourth DC / DC conversion unit 19 into DC power of a predetermined value. The first DC / DC conversion unit 16, the second DC / DC conversion unit 17, and the third DC / DC conversion unit 18 then supply the predetermined value of DC power to the first vehicle-mounted battery 5a, the second vehicle-mounted battery 6a, and the third vehicle-mounted battery 7a, respectively. This power conversion operation allows each vehicle-mounted battery to be charged with power supplied from the commercial power supply 2 and the solar cell 8.

[0233] Moreover, during normal operation, first, the first DC / DC converter 16, the second DC / DC converter 17, and the third DC / DC converter 18 convert the DC power (discharged power) output from the first vehicle-mounted battery 5a, the second vehicle-mounted battery 6a, and the third vehicle-mounted battery 7a into DC power of a specific value, respectively. Furthermore, the fourth DC / DC converter 19 converts the DC power (generated power) input from the solar cell 8 into DC power of a specific value.

[0234] Next, the three AC / DC conversion units 13 to 15 convert the DC power output from the first DC / DC conversion unit 16, the second DC / DC conversion unit 17, the third DC / DC conversion unit 18, and the fourth DC / DC conversion unit 19 into AC power. The three AC / DC conversion units 13 to 15 then output the converted AC power to the commercial power supply 2 via the first relay 11. Through this operation, the DC power (discharged power) output from the first vehicle-mounted battery 5a, the second vehicle-mounted battery 6a, and the third vehicle-mounted battery 7a, and the DC power (generated power) output from the solar cell 8 can be used to adjust the power received from the commercial power supply 2.

[0235] (During a power outage) In the power conversion system 20 of this embodiment, when the commercial power supply 2 experiences a power outage, the control unit 10 turns off the first relay 11 and turns on the second relay 12, switching the connection of the power supply path switch 3 to the power conversion system 20 side. Then, during a power outage, the control unit 10 controls the power conversion system 20 to perform the following power conversion between the load 4 and each of the first vehicle battery 5a, the second vehicle battery 6a, the third vehicle battery 7a, and the solar cell 8.

[0236] During a power outage, first, the first DC / DC converter 16, the second DC / DC converter 17, and the third DC / DC converter 18 convert the DC power (discharged power) output from the first vehicle-mounted battery 5a, the second vehicle-mounted battery 6a, and the third vehicle-mounted battery 7a into DC power of a specific value, respectively. Also, the fourth DC / DC converter 19 converts the DC power (generated power) input from the solar cell 8 into DC power of a specific value.

[0237] Next, the three AC / DC conversion units 13 to 15 convert into AC power the DC power output from the first DC / DC conversion unit 16, the second DC / DC conversion unit 17, the third DC / DC conversion unit 18, and the fourth DC / DC conversion unit 19. Then, the three AC / DC conversion units 13 to 15 output the converted AC power to the load 4 via the second relay 12 and the power supply path switch 3.

[0238] Furthermore, in the event of a power outage, as in the first embodiment described above, power is supplied from the in-vehicle battery with a sufficient charge margin among the first in-vehicle battery 5a, the second in-vehicle battery 6a, and the third in-vehicle battery 7a to the in-vehicle battery with an insufficient charge margin, depending on the consumed / regenerated power of the load 4. In other words, in the present embodiment as well, in the event of a power outage, the in-vehicle battery with an insufficient charge margin is charged by discharge power from the in-vehicle battery with an insufficient charge margin, depending on the consumed / regenerated power of the load 4.

[0239] Therefore, in the power conversion system 20, similar to the first embodiment described above, even if the commercial power supply 2 experiences a power outage, backup power can be supplied to the load 4 using the power stored in the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a, as well as the power generated by the solar cell 8. Note that in the power conversion system 20 of this embodiment, if the power generated by the solar cell 8 is greater than the power consumed by the load 4 during a power outage of the commercial power supply 2, the power generated by the solar cell 8 can be used to charge the vehicle batteries while power is being supplied to the load 4.

[0240] [Power conversion control method (charge / discharge control method for each onboard battery)] The power conversion control method in the power conversion system 20 of this embodiment during a power outage of the commercial power source 2, i.e., the charge / discharge control method for each on-board battery, can be implemented in the same manner as the methods in the various power conversion control examples (see Figures 2 to 14) described in the first embodiment.

[0241] However, in this embodiment, because the power generated by the solar cell 8 is input to the power conversion system 20, the first threshold power Pth1 set for the power Pld of the load 4 is increased and the second threshold power Pth2 is decreased by the amount of the power generated by the solar cell 8. Specifically, ignoring power conversion efficiency, the first threshold power Pth1 for the power Pld of the load 4 can be set to roughly the value obtained by adding the power generated by the solar cell 8 to the maximum discharge power of a main vehicle battery (main vehicle battery group) that has a sufficient margin of charge among the multiple vehicle batteries connected to the power conversion system 20. Furthermore, ignoring power conversion efficiency, the second threshold power Pth2 can be set to roughly the value obtained by subtracting the power generated by the solar cell 8 from the maximum charge power of a sub-vehicle battery (sub-vehicle battery group) that has an insufficient margin of charge among the multiple vehicle batteries connected to the power conversion system 20.

[0242] In the power conversion control of this embodiment, after a power outage occurs, during the power consumption period of the load 4, if the power consumption of the load 4 is lower than the first threshold power Pth1, power is supplied not only to the load 4 but also to the sub-vehicle battery from the main vehicle battery and solar cell 8 (the second operation mode described above). Also, after a power outage occurs, during the power regeneration period of the load 4, power is supplied to the sub-vehicle battery or to both the main vehicle battery and the sub-vehicle battery using the regenerated power of the load 4 and the generated power of the solar cell 8 (the third and fourth operation modes described above).

[0243] Therefore, in the power conversion system 20 of this embodiment, similar to the first embodiment, even if backup power is supplied to the load 4 after a power outage occurs, it is possible to prevent the charge state of the sub-vehicle battery from decreasing to the lower discharge limit, and it is possible to extend the duration of backup power supply to the load 4 during a power outage. That is, this embodiment can achieve the same effects as the first embodiment.

[0244] Furthermore, in this embodiment, the power conversion system 20 is connected not only to the commercial power source 2 but also to the solar cell 8, and since power can be supplied from the solar cell 8 to the load 4 and / or the on-board battery during a power outage, the duration of backup power supply to the load 4 during a power outage can be further extended. Therefore, in this embodiment, when backing up power to the load 4 (equipment) using multiple on-board batteries during a power outage, power supply to the load 4 can be continued more stably even if the multiple electric vehicles include an electric vehicle that is not fully charged.

[0245] 3. Third embodiment In the above embodiment, a configuration example in which multiple on-board power sources are connected to one power conversion system has been described, but the present invention is not limited to this. For example, multiple on-board power sources may be connected separately to multiple power conversion systems, and the multiple power conversion systems may be connected in parallel. In other words, multiple power conversion systems may be connected in parallel to form one power conversion system. In the third embodiment, one such configuration example will be described.

[0246] [Power conversion system configuration] Fig. 16 is a schematic configuration diagram of a power conversion system according to the third embodiment of the present invention. In the power conversion system 30 of the third embodiment shown in Fig. 16, components similar to those of the power conversion system 20 of the second embodiment (see Fig. 15) are denoted by the same reference numerals, and description of these components will be omitted.

[0247] 16, the power conversion system 30 of this embodiment includes a first power conversion system 31 connected to a first in-vehicle battery 5a and a second in-vehicle battery 6a, and a second power conversion system 32 connected to a third in-vehicle battery 7a and a solar cell 8. The first power conversion system 31 and the second power conversion system 32 are connected in parallel to the commercial power supply 2 and the load 4.

[0248] As shown in FIG. 16, the first power conversion system 31 includes a control unit 40, a first relay 41, a second relay 42, an AC / DC conversion unit 43, a first DC / DC conversion unit 44, and a second DC / DC conversion unit 45.

[0249] 16 , the control unit 40 is connected to each of the first relay 41, the second relay 42, the AC / DC conversion unit 43, the first DC / DC conversion unit 44, and the second DC / DC conversion unit 45. The control unit 40 is also connected to the power supply path switch 3 and a control unit 50 (described later) in the second power conversion system 32. In this embodiment, the control unit 40 outputs a control signal to the control unit 50 (described later) in the second power conversion system 32, thereby synchronously controlling (parallel controlling) the first power conversion system 31 and the second power conversion system 32.

[0250] 16, one input / output terminal of the first relay 41 is connected to the output terminal of the commercial power source 2 and the input terminal of the power supply path switch 3 on the commercial power source 2 side. Also, one input / output terminal of the second relay 42 is connected to the input / output terminal of the power supply path switch 3 on the power conversion system 30 side.

[0251] The other input / output terminal of the first relay 11 and the other input / output terminal of the second relay 12 are connected to input / output terminals on the AC power side of the AC / DC conversion unit 43. The input / output terminals on the DC power side of the AC / DC conversion unit 43 are connected to one input / output terminal of the first DC / DC conversion unit 44 and one input / output terminal of the second DC / DC conversion unit 45.

[0252] The other input / output terminal of the first DC / DC conversion unit 44 is connected to the first on-board battery 5a of the first electric vehicle 5, and the other input / output terminal of the second DC / DC conversion unit 17 is connected to the second on-board battery 6a of the second electric vehicle 6.

[0253] 16 , the second power conversion system 32 includes a control unit 50, a first relay 51, a second relay 52, an AC / DC conversion unit 53, a first DC / DC conversion unit 54, and a second DC / DC conversion unit 55. In this embodiment, each component included in the second power conversion system 32 has the same configuration as the corresponding component included in the first power conversion system 31.

[0254] Furthermore, the electrical connection between the components in the second power conversion system 32 is similar to that between the components in the first power conversion system 31. However, in the second power conversion system 32, the other input / output terminal of the first DC / DC conversion unit 54 is connected to the third on-board battery 7a of the third electric vehicle 7, and the other input / output terminal of the second DC / DC conversion unit 55 is connected to the solar cell 8.

[0255] In the present embodiment, an example is described in which one AC / DC conversion unit 43 is provided inside each of the first power conversion system 31 and the second power conversion system 32, but the present invention is not limited to this. For example, as in the first embodiment, each power conversion system may be configured to have the same number of AC / DC conversion units as the number of DC / DC conversion units, and these AC / DC conversion units may be connected in parallel. However, when one AC / DC conversion unit is provided as in the present embodiment, it becomes possible to fabricate, for example, the AC / DC conversion unit, the first DC / DC conversion unit, and the second DC / DC conversion unit together on a single chip, which is advantageous in terms of mass production (cost).

[0256] Furthermore, in this embodiment, the configuration of the second power conversion system 32 is the same as the configuration of the first power conversion system 31. Therefore, as in the first power conversion system 31, a control signal line 56 for connecting the control unit 50 and the power supply path switch 3 is provided in the second power conversion system 32, as shown by the dashed line (control signal line) in Fig. 16 . However, in this embodiment, the control signal line 56 in the second power conversion system 32 is not connected to the power supply path switch 3, and the switching operation of the power supply path switch 3 is performed only by the control unit 40 in the first power conversion system 31. If the configuration of the second power conversion system 32 is the same as the configuration of the first power conversion system 31, an advantage is obtained in terms of mass production (cost).

[0257] [Power conversion system operation overview and power conversion control method] In the power conversion system 30 of this embodiment, during normal operation when the commercial power source 2 is not experiencing a power outage, the control unit 40 in the first power conversion system 31 turns on the first relay 41 and turns off the second relay 42, switching the connection of the power supply path switch 3 to the commercial power source 2 side. At this time, the control unit 50 in the second power conversion system 32 turns on the first relay 51 and turns off the second relay 52. ​​During normal operation, the control units 40 and 50 perform synchronized control to perform power conversion between the commercial power source 2 and each of the first vehicle battery 5a, the second vehicle battery 6a, the third vehicle battery 7a, and the solar cell 8, in the same manner as in the second embodiment.

[0258] Furthermore, during a power outage of the commercial power source 2, the control unit 40 in the first power conversion system 31 turns off the first relay 41 and turns on the second relay 42, switching the connection of the power supply path switch 3 to the power conversion system 30 side. At this time, the control unit 50 in the second power conversion system 32 turns off the first relay 51 and turns on the second relay 52. ​​During a power outage, the control units 40 and 50 perform synchronous control to perform power conversion between the load 4 and each of the first vehicle battery 5a, the second vehicle battery 6a, the third vehicle battery 7a, and the solar cell 8, in the same manner as in the second embodiment.

[0259] Furthermore, the power conversion control method in the power conversion system 30 of this embodiment, i.e., the method for controlling the charging / discharging of each on-board battery, during a power outage of the commercial power source 2 can be implemented in the same manner as the methods in the various power conversion control examples described in the first and second embodiments. However, in this embodiment, the power conversion control during a power outage of the commercial power source 2 is performed by synchronous control (parallel control) by the control unit 40 of the first power conversion system 31 and the control unit 50 of the second power conversion system 32.

[0260] [Various effects] As described above, the power conversion system 30 of this embodiment can perform power conversion control in the same manner as the power conversion system 20 of the second embodiment, and therefore can obtain the same effects as those of the second embodiment.

[0261] Furthermore, in this embodiment, a single power conversion system is constructed by connecting multiple power conversion systems in parallel, so that, for example, requests such as an increase in power capacity (power capacity of the load and on-board battery) or an increase in the number of connected vehicles can be met simply by increasing the number of power conversion systems connected in parallel.

[0262] Furthermore, as in this embodiment, by reducing the number of on-board batteries, solar cells, etc. connected to one power conversion system (two in the example shown in FIG. 16 ) from, for example, that of the first and second embodiments (three and four), the power capacity borne by one power conversion system is reduced. In this case, the minimum power capacity that can be supported by the entire power conversion system 30 can be made smaller than that of the first and second embodiments. Also, in this case, by changing the number of power conversion systems connected in parallel, the supportable power capacity can be set in finer power capacity intervals. Therefore, in this embodiment, the range of power capacity applicable to the power conversion system can be easily expanded, making it easier to build a power conversion system that can meet various needs.

[0263] 4. Fourth Embodiment In the above-described various embodiments, a configuration example has been described in which a control unit that controls the operation of the power conversion system and a power conversion unit that includes a relay, an AC / DC conversion unit, a DC / DC conversion unit, etc. are provided within the power conversion system. However, the present invention is not limited to this. For example, the control unit and the power conversion unit may be configured separately. In the fourth embodiment, one such configuration example will be described.

[0264] [Power conversion system configuration] Fig. 17 is a schematic configuration diagram of a power conversion system according to a fourth embodiment of the present invention. In a power conversion system 60 of the fourth embodiment shown in Fig. 17, components similar to those of the power conversion system 1 of the first embodiment (see Fig. 1) are denoted by the same reference numerals, and description of these components will be omitted.

[0265] As shown in FIG. 17, the power conversion system 60 includes a power conversion control device 61 and a power conversion device 62.

[0266] The power conversion control device 61 is composed of an information processing device that can execute the control function of the power conversion operation between the commercial power source 2 or the load 4 and multiple vehicle batteries (first vehicle battery 5a, second vehicle battery 6a, third vehicle battery 7a) using the control unit described in the various embodiments above.

[0267] The power conversion device 62 is electrically connected to the power conversion control device 61 and performs power conversion operations between the commercial power source 2 or the load 4 and multiple vehicle batteries (first vehicle battery 5a, second vehicle battery 6a, and third vehicle battery 7a) based on control signals input from the power conversion control device 61. As shown in FIG. 17 , the power conversion device 62 includes a first relay 11, a second relay 12, three AC / DC conversion units 13 to 15, a first DC / DC conversion unit 16, a second DC / DC conversion unit 17, and a third DC / DC conversion unit 18. The configuration of each component within the power conversion device 62, the connection between the components, and the connection between each component within the power conversion device 62 and the commercial power source 2, the load 4, the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a are the same as those in the first embodiment.

[0268] In this embodiment, an example will be described in which the power conversion control device 61 and the power conversion device 62 are directly and electrically connected, but the present invention is not limited to this. For example, a communication function unit may be provided inside both the power conversion control device 61 and the power conversion device 62, and the power conversion control device 61 and the power conversion device 62 may be connected to each other so that they can communicate with each other, and a control signal may be transmitted from the power conversion control device 61 to the power conversion device 62 via communication.

[0269] [Hardware configuration of power conversion control device] The power conversion control device 61 of this embodiment can be configured by an information processing device such as a computer device having a calculation function and a communication function. Fig. 18 is a block diagram showing an example of the hardware configuration of a computer device 100 that can be used as the power conversion control device 61.

[0270] The computer device 100 includes a CPU 101, a ROM 102, and a RAM 103, all connected to a bus line 109. The computer device 100 also includes a network I / F (interface) 104, an operation unit 105, a display unit 106, a data input / output I / F 107, and a non-volatile storage 108, all connected to the bus line 109.

[0271] The CPU 101 reads out program code of software for realizing various processing functions of the power conversion control device 61 from the ROM 102 to the RAM 103 and executes the program code. At this time, variables and parameters generated during the calculation process are also temporarily written to the RAM 103. That is, the power conversion control process (charge / discharge control process for each on-board battery) performed in the various embodiments described above is executed by the CPU 101 (control unit).

[0272] The network I / F 104 is configured by, for example, a network interface card (NIC) or the like, and transmits and receives various data to and from each device connected via wireless communication.

[0273] The operation unit 105 is configured with, for example, keys and buttons, and generates an operation signal according to the operation content input by the user and supplies the operation signal to the CPU 101. The display unit 106 is configured with, for example, a liquid crystal panel, and displays characters, images, and the like on the screen. The display unit 106 may also be configured with a touch panel, in which case the display unit 106 and the operation unit 105 are configured integrally.

[0274] The data input / output I / F 107 includes various interfaces used when executing input / output processing of various data (various information) between the computer device 100 and external devices. In this embodiment, input of a control signal from the power conversion control device 61 to the power conversion device 62 can be executed via the data input / output I / F 107.

[0275] The nonvolatile storage 108 can be configured, for example, with a hard disk drive (HDD), a solid state drive (SSD), a flexible disk, an optical disk, a magneto-optical disk, a compact disc (CD)-ROM, a CD-R, a magnetic tape, a nonvolatile memory, etc. The nonvolatile storage 108 stores an operating system (OS), various parameters, and various programs for causing the computer device 100 to function as the power conversion control device 61. Note that information (data) such as programs, tables, and files for realizing the various functions of the power conversion control device 61 may be stored in a recording medium other than the ROM 102 or the nonvolatile storage 108, such as an integrated circuit (IC) card, an SD card, or a digital versatile disc (DVD).

[0276] [Power conversion system operation overview and power conversion control method] In the power conversion system 60 of this embodiment, during normal times when the commercial power source 2 is not experiencing a power outage, the power conversion control device 61 turns on the first relay 41 and turns off the second relay 42 in the power conversion device 62, and switches the connection of the power supply path switch 3 to the commercial power source 2 side. During normal times, the power conversion control device 61 controls each component in the power conversion device 62 to control the power conversion operation between the commercial power source 2 and each of the first vehicle battery 5a, the second vehicle battery 6a, and the third vehicle battery 7a, in the same manner as in the first embodiment.

[0277] Furthermore, during a power outage of the commercial power source 2, the power conversion control device 61 turns off the first relay 41 in the power conversion device 62, turns on the second relay 42, and switches the connection of the power supply path switch 3 to the power conversion device 62 side. During a power outage, the power conversion control device 61 controls each component in the power conversion device 62, and controls the power conversion operation between the load 4 and each of the first vehicle battery 5a, second vehicle battery 6a, and third vehicle battery 7a, in the same manner as in the first embodiment.

[0278] In addition, the power conversion control method in the power conversion control device 61 of this embodiment, i.e., the charge / discharge control method for each on-board battery, when the commercial power source 2 fails can be implemented in the same manner as the methods in the various power conversion control examples described in the first embodiment.

[0279] [effect] The power conversion control device 61 of this embodiment can control the power conversion operation of the power conversion device 62 in the same manner as the power conversion system 1 of the first embodiment. Therefore, this embodiment also provides the same effects as the first embodiment.

[0280] 5. Various Modifications Although the power conversion system and the power conversion control device according to various embodiments of the present invention have been described above, the present invention is not limited to these, and various other modifications are possible without departing from the spirit of the present invention as set forth in the claims. For example, the following various modifications can be adopted, and the following various modifications can also achieve the same effects as the above various embodiments.

[0281] In the various embodiments described above, examples have been described in which the state of charge of each vehicle battery is determined using SOC (state of charge: the ratio of remaining energy to full charge) as a parameter representing the remaining charge of each vehicle battery, but the present invention is not limited to this. For example, the remaining energy (remaining charge amount) may be used instead of SOC as a parameter representing the remaining charge of each vehicle battery. In this case, the first threshold value Sth1 for determining whether or not an vehicle battery is the main vehicle battery and the second threshold value Sth2 for determining whether or not an vehicle battery is the sub-vehicle battery are also set using the remaining energy value.

[0282] In the various embodiments or variations described above, when determining the remaining charge status of each vehicle battery using the SOC (percentage of remaining energy) or the value of remaining energy, a hysteresis (adjustment sensitivity) function may be provided to prevent frequent switching of control and unstable operation.

[0283] Furthermore, in the various embodiments described above, an example has been described in which one of three on-board batteries connected to a power conversion system is a main on-board battery with a sufficient charge margin or a sub-on-board battery with a limited charge margin. However, the present invention is not limited to this. The power conversion technology of the present invention described above can also be applied to cases in which, for example, four or more on-board batteries are connected to a power conversion system, including multiple on-board batteries that can serve as main on-board batteries and multiple on-board batteries that can serve as sub-on-board batteries. In such cases, the first threshold power Pth1 and the second threshold power Pth2 of the load are set based on the maximum discharge power of a main on-board battery group consisting of multiple main on-board batteries and the maximum charge power of a sub-on-board battery group consisting of multiple sub-on-board batteries. Then, based on these set threshold powers, the charge / discharge operation of each main on-board battery and each sub-on-board battery is controlled in the same manner as in the various embodiments described above.

[0284] In the various embodiments described above, configuration examples in which the power conversion control process by the power conversion system is executed on software have been described, but the present invention is not limited to this. For example, some or all of the power conversion control process may be executed on hardware.

[0285] Furthermore, the various embodiments described above have described the configuration of the device in detail and specifically in order to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. The position, size, shape, range, etc. of each component shown in the drawings, etc. may not represent the actual position, size, shape, range, etc. in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings, etc. [Explanation of symbols]

[0286] DESCRIPTION OF SYMBOLS 1, 20, 30, 60... power conversion system, 2... commercial power source, 3... power supply path switch, 4... load, 5... first electric vehicle, 5a... first on-board battery, 6... second electric vehicle, 6a... second on-board battery, 7... third electric vehicle, 7a... third on-board battery, 8... solar cell, 10, 40, 50... control unit, 31... first power conversion system, 32... second power conversion system, 61... power conversion control device , 62...power conversion device, Sth1...first threshold of SOC, Sth2...second threshold of SOC, Sth3...third threshold of SOC (lower discharge limit), Pld...load power, Pth1...first threshold power, Pth2...second threshold power, P1...power of first vehicle battery, P2...power of second vehicle battery, P3...power of third vehicle battery, Ph1, Ph2, Ph3...maximum discharge power, Pj1, Pj2, Pj3...maximum charge power

Claims

1. A power conversion system is connected to a plurality of vehicle batteries mounted on a plurality of vehicles, a commercial power source, and a load, and is capable of converting AC power input from the commercial power source into DC power and supplying the DC power to each of the plurality of vehicle batteries, In the event of a power outage from the commercial power supply, a first operation of supplying power to the load from both some of the on-board batteries included in the plurality of on-board batteries and some other on-board batteries included in the plurality of on-board batteries and having a parameter value representing a remaining charge amount lower than that of the some of the on-board batteries; and a control unit capable of performing a second operation of, when power consumption in the load decreases during execution of the first operation, continuing to supply power from the part of the on-board batteries to the load and switching the operation mode of the other part of the on-board batteries from discharging to charging. A power conversion system comprising:

2. The control unit performs the second operation when power consumption in the load becomes smaller than a predetermined threshold power during the execution of the first operation. The power conversion system according to claim 1 .

3. The predetermined threshold power is set based on the maximum discharge power of the part of the vehicle-mounted batteries.

3. The power conversion system according to claim 2.

4. a value of a parameter representing the remaining charge amount of an on-board battery included in the portion of the on-board batteries is equal to or greater than a first threshold value; The value of the parameter representing the remaining charge amount of the in-vehicle battery included in the other part of the in-vehicle batteries is equal to or less than a second threshold value that is smaller than the first threshold value.

3. The power conversion system according to claim 2.

5. The parameter representing the remaining charge amount of the vehicle-mounted battery is the ratio of the remaining charge amount to the fully charged amount of the vehicle-mounted battery.

5. The power conversion system according to claim 4.

6. The parameter representing the remaining charge amount of the vehicle battery is the remaining charge amount.

5. The power conversion system according to claim 4.

7. The load includes equipment that performs a power running operation that converts electric power into mechanical energy and a regenerative operation that converts mechanical energy into electric power, When the commercial power supply is interrupted, the control unit a third operation of supplying power from both the load and the portion of the on-board batteries to the other portion of the on-board batteries when power is output from the load in association with the regenerative operation of the equipment; If the power output from the load increases during execution of the third operation, a fourth operation can be performed in which the power supply from the load to the other part of the on-board batteries is continued and the operation mode of the part of the on-board batteries is switched from discharging to charging. The power conversion system according to claim 1 .

8. The control unit performs the fourth operation when the power output from the load becomes greater than a specific threshold power during the execution of the third operation.

8. The power conversion system according to claim 7.

9. The specific threshold power is set based on the maximum charging power of the other part of the on-board batteries.

9. The power conversion system according to claim 8.

10. A power conversion control device is connected to a plurality of on-board batteries mounted on a plurality of vehicles, a commercial power source, and a load, and controls the operation of a power conversion device that converts AC power input from the commercial power source into DC power and can supply the DC power to each of the plurality of on-board batteries, In the event of a power outage from the commercial power supply, a first operation of supplying power to the load from both some of the on-board batteries included in the plurality of on-board batteries and some other on-board batteries included in the plurality of on-board batteries and having a parameter value representing a remaining charge amount lower than that of the some of the on-board batteries; and a control unit capable of performing a second operation of, when power consumption in the load decreases during execution of the first operation, continuing to supply power from the part of the on-board batteries to the load and switching the operation mode of the other part of the on-board batteries from discharging to charging. A power conversion control device characterized by:

Images