charger

Abstract

To reduce the user's time and effort at the time of switching the power supply mode while suppressing increase in the manufacturing cost of a charger.SOLUTION: When a first accumulator B1 is connected with a charger Ch and residual capacity Cr1 is equal to or less than a first threshold Cr1th and residual capacity Cr2 is equal to or less than a second threshold Cr2th, power from a system power supply SP is supplied to the first accumulator B1. When the first accumulator B1 is not connected with the charger Ch and the residual capacity Cr2 is equal to or less than the second threshold Cr2th, the power from the system power supply SP is supplied to a second accumulator B2. When the first accumulator B1 is connected with the charger Ch and the residual capacity Cr1 is equal to or less than the first threshold Cr1th and the residual capacity Cr2 is larger than the second threshold Cr2th, the power from the system power supply SP and power from the second accumulator B2 are supplied to the first accumulator B1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a charger. [Background technology]

[0002] There is a charger in which a user operates a switch to switch between a power supply mode in which power supplied from a power grid is supplied to a first power storage device and a power supply mode in which power supplied from the power grid is supplied to a second power storage device. Related technology is disclosed in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-002451 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are concerns that the switch for switching the power supply mode in the charger increases manufacturing costs, and that switching the power supply mode requires the user to operate the switch, which is time-consuming.

[0005] An object according to one aspect of the present invention is to reduce the effort required by a user when switching power supply modes while suppressing an increase in the manufacturing cost of a charger. [Means for solving the problem]

[0006] One form of the charger according to the present invention is a charger that supplies power from a system power source to a first storage battery or a second storage battery, and includes a connection determination unit that determines whether the first storage battery is connected to the charger, a remaining capacity acquisition unit that acquires the remaining capacity of each of the first and second storage batteries, and a power supply unit that supplies power to the first storage battery or the second storage battery based on the connection determination result by the connection determination unit and the remaining capacity of each of the first and second storage batteries acquired by the remaining capacity acquisition unit.

[0007] The power supply unit supplies power from the system power supply to the first storage battery when the first storage battery is connected to the charger, the remaining capacity of the first storage battery is equal to or less than a first threshold, and the remaining capacity of the second storage battery is equal to or less than a second threshold; supplies power from the system power supply to the second storage battery when the first storage battery is not connected to the charger and the remaining capacity of the second storage battery is equal to or less than the second threshold, or when the first storage battery is connected to the charger, the remaining capacity of the first storage battery is greater than the first threshold, and the remaining capacity of the second storage battery is equal to or less than the second threshold; and supplies power from the system power supply and power from the second storage battery to the first storage battery when the first storage battery is connected to the charger, the remaining capacity of the first storage battery is equal to or less than the first threshold, and the remaining capacity of the second storage battery is greater than the second threshold.

[0008] This eliminates the need to provide the charger with a switch for switching the power supply mode, thereby suppressing increases in the manufacturing costs of the charger. Also, the power supply mode can be automatically switched depending on the connection state between the first storage battery and the charger and the remaining capacity of the first and second storage batteries, reducing the user's effort when switching the power supply mode.

[0009] Furthermore, the power supply unit may be configured to supply power from the system power supply to the second storage battery via a voltage conversion circuit when the first storage battery is not connected to the charger and the remaining capacity of the second storage battery is equal to or less than the second threshold, or when the first storage battery is connected to the charger and the remaining capacity of the first storage battery is greater than the first threshold and the remaining capacity of the second storage battery is equal to or less than the second threshold, and to supply power from the system power supply and power supplied from the second storage battery via the voltage conversion circuit to the first storage battery when the first storage battery is connected to the charger and the remaining capacity of the first storage battery is equal to or less than the first threshold and the remaining capacity of the second storage battery is greater than the second threshold.

[0010] This allows the power output from the voltage conversion circuit to the charger to be varied, thereby allowing the power supplied from the charger to the first storage battery to be varied, thereby increasing the degree of freedom in the power supply from the charger to the first storage battery.

[0011] Furthermore, the power supply unit may be configured to change the output voltage of the voltage conversion circuit depending on the type of power source other than the system power source when the first storage battery is connected to the charger, the remaining capacity of the first storage battery is less than or equal to the first threshold, the remaining capacity of the second storage battery is greater than the second threshold, and a power source other than the system power source is connected to the second storage battery.

[0012] As a result, for example, when a power source other than the system power source is connected to the second storage battery, the power supplied from the second storage battery to the charger can be increased and the power supplied from the system power source to the charger can be decreased compared to when a power source other than the system power source is not connected to the second storage battery, thereby reducing the power consumption of the system power source while preventing the second storage battery from entering an over-discharge state. [Effects of the Invention]

[0013] According to the present invention, it is possible to reduce the effort required of a user when switching between power supply modes while suppressing an increase in the manufacturing cost of a charger. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating an example of a charger according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of a first storage battery, a second storage battery, and a charger. [Figure 3] 10 is a flowchart illustrating an example of the operation of a control unit. [Figure 4] FIG. 10 is a diagram illustrating a modified example of the charger according to the embodiment. [Figure 5] 10 is a flowchart showing a modified example of the operation of the control unit. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0016] FIG. 1 is a diagram illustrating an example of a charger according to an embodiment.

[0017] The charger Ch shown in FIG. 1 supplies power supplied from a power system SP to a first power storage device S1 or a second power storage device S2.

[0018] The power supply system SP is, for example, a three-phase, three-wire power supply system, and supplies AC power to the charger Ch. Note that the power supply system SP is not limited to a three-phase, three-wire power supply system.

[0019] The first power storage device S1 is mounted on a vehicle, such as an industrial vehicle such as a forklift or an electric vehicle, and supplies power to a load mounted on the industrial vehicle or the vehicle. When the charger Ch and the first power storage device S1 are connected to each other via a charging cable (not shown), power can be supplied from the charger Ch to the first power storage device S1.

[0020] The second power storage device S2 is constantly connected to the charger Ch, and supplementarily supplies electric power to the first power storage device S1 via the charger Ch. That is, the charger Ch of the embodiment is effective when power is supplied preferentially to the first power storage device S1 over the second power storage device S2.

[0021] FIG. 2 is a diagram showing an example of a first power storage device S1, a second power storage device S2, and a charger Ch.

[0022] The first power storage device S1 includes a first storage battery B1, external terminals Ts1 to Ts4, and a control unit Cnt1.

[0023] The positive terminal of the first storage battery B1 is connected to the external terminals Ts1 and Ts3, and the negative terminal of the first storage battery B1 is connected to the external terminal Ts2.

[0024] The first storage battery B1 is configured by, for example, a rechargeable secondary battery such as a lithium ion battery.

[0025] The control unit Cnt1 is configured with, for example, a CPU (Central Processing Unit) or a programmable device (such as an FPGA (Field Programmable Gate Array) or a PLD (Programmable Logic Device)), and is connected to an external terminal Ts4 via a communication line Lc1. The control unit Cnt1 also calculates the remaining capacity Cr1 of the first storage battery B1 based on the voltage and current of the first storage battery B1. For example, the remaining capacity Cr1 may be the charge rate [%] of the first storage battery B1 (the ratio of the remaining capacity to the fully charged capacity of the first storage battery B1), the open circuit voltage [V] of the first storage battery B1 when no current is flowing through the first storage battery B1, the closed circuit voltage [V] of the first storage battery B1 when current is flowing through the first storage battery B1, or the integrated value [Ah] of the current flowing through the first storage battery B1.

[0026] The second power storage device S2 includes a second storage battery B2 and a control unit Cnt2.

[0027] The second storage battery B2 is configured by, for example, a rechargeable secondary battery such as a lithium ion battery.

[0028] The control unit Cnt2 is configured by, for example, a CPU or a programmable device. The control unit Cnt2 and the control unit Cnt are connected via a communication line Lc2, enabling communication between the control unit Cnt2 and the control unit Cnt. The control unit Cnt2 calculates the remaining capacity Cr2 of the second storage battery B2 based on the voltage and current of the second storage battery B2. For example, the remaining capacity Cr2 may be the charge rate [%] of the second storage battery B2 (the ratio of the remaining capacity to the fully charged capacity of the second storage battery B2), the open circuit voltage [V] of the second storage battery B2 when no current is flowing through the second storage battery B2, the closed circuit voltage [V] of the second storage battery B2 when current is flowing through the second storage battery B2, or the integrated value [Ah] of the current flowing through the second storage battery B2.

[0029] The charger Ch includes diodes D1 to D8, capacitors C1 to C4, a transformer Tr, switches SW1 to SW4, inductors L1 to L3, resistors R1 and R2, external terminals Tc1 to Tc4, and a control unit Cnt. Note that in Fig. 2, the switches SW1 to SW4 are configured by MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), but are not limited to MOSFETs.

[0030] The connection point between the anode terminal of diode D1 and the cathode terminal of diode D2 is connected to the u-phase of the power system SP, the connection point between the anode terminal of diode D3 and the cathode terminal of diode D4 is connected to the v-phase of the power system SP, and the connection point between the anode terminal of diode D5 and the cathode terminal of diode D6 is connected to the w-phase of the power system SP. The cathode terminals of diodes D1, D3, and D5 are connected to one terminal of capacitor C1, and the anode terminals of diodes D2, D4, and D6 are connected to the other terminal of capacitor C1.

[0031] That is, AC power supplied from the power system SP is rectified by a rectifier circuit made up of diodes D1 to D6 and smoothed by a smoothing circuit made up of a capacitor C1, thereby being converted into DC power.

[0032] One terminal of the primary coil Lp of the transformer Tr is connected to one terminal of the capacitor C1, the other terminal of the primary coil Lp is connected to the drain terminal of the switch SW1, and the source terminal of the switch SW1 is connected to the other terminal of the capacitor C1. One terminal of the secondary coil Ls of the transformer Tr is connected to the anode terminal of the diode D7, and the cathode terminals of the diodes D7 and D8 are connected to one terminal of the capacitor C2 via the inductor L1. The other terminal of the secondary coil Ls is connected to the anode terminal of the diode D8 and the other terminal of the capacitor C2.

[0033] When the switch SW1 is repeatedly turned on and off, the energy stored in the capacitor C1 is transferred from the primary coil Lp to the secondary coil Ls of the transformer Tr, rectified by the diodes D7 and D8, and smoothed by the capacitor C2.

[0034] That is, the voltage converted to DC by diodes D1 to D6 and capacitor C1 is converted to a predetermined voltage by a forward converter consisting of switch SW1, transformer Tr, diodes D7 and D8, inductor L1, and capacitor C2. Note that a flyback converter or a full-bridge converter may be used instead of the forward converter. Also, the forward converter may be omitted.

[0035] Furthermore, the drain terminal of switch SW2 is connected to one terminal of capacitor C2, the source terminal of switch SW2 is connected to the drain terminal of switch SW3, the source terminal of switch SW3 is connected to the drain terminal of switch SW4, and the source terminal of switch SW4 is connected to the other terminal of capacitor C2. The connection point between the source terminal of switch SW2 and the drain terminal of switch SW3 is connected to one terminal of capacitor C3 and the positive terminal of the second storage battery B2 via inductor L2, and the other terminal of capacitor C3 is connected to the drain terminal of switch SW4 and the negative terminal of the second storage battery B2. Furthermore, the connection point between the source terminal of switch SW3 and the drain terminal of switch SW4 is connected to one terminal of capacitor C4 and the external terminal Tc1 via inductor L3, and the other terminal of capacitor C4 is connected to the source terminal of switch SW4 and the external terminal Tc2.

[0036] When the charger Ch and the first power storage device S1 are connected via a charging cable (not shown), the external terminals Tc1 and Ts1 are connected to each other, and the external terminals Tc2 and Ts2 are connected to each other. When the external terminals Tc1 and Ts1 are connected to each other and the external terminals Tc2 and Ts2 are connected to each other, the capacitor C4 and the first storage battery B1 are connected to each other, and a state is established in which power supplied from the power system SP and power supplied from the second storage battery B2 can be supplied to the first storage battery B1. In this state, by repeatedly turning on the switches SW1 to SW3 and turning off the switch SW4, and then turning off the switches SW1 to SW3 and turning on the switch SW4, the power supplied from the power system SP is supplied to the first storage battery B1. Furthermore, by repeatedly turning on switches SW1 and SW2 and turning off switches SW3 and SW4, and then turning off switches SW1 and SW2 and turning on switches SW3 and SW4, power supplied from the system power supply SP is supplied to the second storage battery B2. By repeatedly turning on switches SW1 to SW3 and turning off switch SW4, and then turning off switches SW1, SW2, and SW4 and turning on switch SW3, power supplied from the system power supply SP and power supplied from the second storage battery B2 are supplied to the first storage battery B1. Note that the on / off timing of switch SW1 does not have to be synchronized with the on / off timing of switches SW2 to SW4.

[0037] Furthermore, one terminal of resistor R1 is connected to external terminal Tc3, the other terminal of resistor R1 is connected to one terminal of resistor R2, and the other terminal of resistor R2 is connected to the other terminal of capacitor C4 and external terminal Tc2. When charger Ch and first power storage device S1 are connected via a charging cable (not shown), external terminal Tc3 and external terminal Ts3 are connected to each other. When external terminal Tc3 and external terminal Ts3 are connected to each other, the voltage of first storage battery B1 is applied to resistor R1 and resistor R2, and voltage Vd becomes equal to or greater than threshold Vdth.

[0038] The control unit Cnt is configured by, for example, a CPU or a programmable device, and controls the operation of each of the switches SW1 to SW4.

[0039] Furthermore, the control unit Cnt receives a voltage Vd divided by resistors R1 and R2.

[0040] Furthermore, the control unit Cnt is connected to the external terminal Tc4 via a communication line Lcc. When the charger Ch and the first power storage device S1 are connected via a charging cable (not shown), the external terminal Tc4 and the external terminal Ts4 are connected to each other. When the external terminal Tc4 and the external terminal Ts4 are connected to each other, the communication line Lcc and the communication line Lc1 are connected to each other, enabling communication between the control unit Cnt and the control unit Cnt1.

[0041] The control unit Cnt includes a connection determination unit 1, a remaining capacity acquisition unit 2, and a power supply unit 3.

[0042] The connection determination unit 1 determines whether the first storage battery B1 is connected to the charger Ch. For example, if the voltage Vd is lower than the threshold Vdth, the connection determination unit 1 determines that the first storage battery B1 is not connected to the charger Ch, and if the voltage Vd is equal to or higher than the threshold Vdth, the connection determination unit 1 determines that the first storage battery B1 is connected to the charger Ch.

[0043] The remaining capacity acquiring unit 2 acquires the remaining capacity Cr1 of the first storage battery B1 and the remaining capacity Cr2 of the second storage battery B2. For example, after the control unit Cnt and the control unit Cnt1 are able to communicate with each other, the remaining capacity acquiring unit 2 acquires the remaining capacity Cr1 by receiving data indicating the remaining capacity Cr1 from the control unit Cnt1. The remaining capacity acquiring unit 2 also acquires the remaining capacity Cr2 by receiving data indicating the remaining capacity Cr2 from the control unit Cnt2.

[0044] When the first storage battery B1 is connected to the charger Ch, and the remaining capacity Cr1 of the first storage battery B1 is equal to or less than the first threshold value Cr1th, and the remaining capacity Cr2 of the second storage battery B2 is equal to or less than the second threshold value Cr2th, that is, when the first storage battery B1 needs to be charged but the remaining capacity Cr2 of the second storage battery B2 is insufficient, the power supply unit 3 supplies power supplied from the system power source SP to the first storage battery B1 (power supply mode M1). Note that, for example, the first threshold value Cr1th is set to the remaining capacity Cr1 of the first storage battery B1 required to continue operating the industrial vehicle or vehicle for a predetermined time. This allows the first storage battery B1 to be charged with at least the power supplied from the system power source SP, thereby preventing the industrial vehicle or vehicle from being unable to operate due to insufficient remaining capacity Cr1 of the first storage battery B1.

[0045] For example, when executing power supply mode M1, the power supply unit 3 turns on switches SW1 to SW3 and turns off switch SW4, and then repeatedly turns off switches SW1 to SW3 and turns on switch SW4, thereby allowing power supplied from the system power supply SP to be supplied to the first storage battery B1.

[0046] Furthermore, when the first storage battery B1 is not connected to the charger Ch and the remaining capacity Cr2 of the second storage battery B2 is equal to or less than the second threshold Cr2th, i.e., when the first storage battery B1 cannot be charged but the second storage battery B2 needs to be charged, the power supply unit 3 supplies power supplied from the system power supply SP to the second storage battery B2 (power supply mode M2). Alternatively, when the first storage battery B1 is connected to the charger Ch and the remaining capacity Cr1 of the first storage battery B1 is greater than the first threshold Cr1th and the remaining capacity Cr2 of the second storage battery B2 is equal to or less than the second threshold Cr2th, i.e., when the first storage battery B1 does not need to be charged but the second storage battery B2 needs to be charged, the power supply unit 3 supplies power supplied from the system power supply SP to the second storage battery B2 (power supply mode M2). Note that the second threshold Cr2th is the remaining capacity Cr2 of the second storage battery B2 immediately before it entered an over-discharge state. This makes it possible to prevent the second storage battery B2 from being over-discharged. Furthermore, by executing the power supply mode M2, the second storage battery B2 can be charged when the industrial vehicle or other vehicle is operating at night when electricity rates are relatively low.

[0047] For example, when executing the power supply mode M2, the power supply unit 3 turns on the switches SW1 and SW2 and turns off the switches SW3 and SW4, and then repeatedly turns off the switches SW1 and SW2 and turns on the switches SW3 and SW4, thereby allowing the power supplied from the system power supply SP to be supplied to the second storage battery B2.

[0048] Furthermore, when the first storage battery B1 is connected to the charger Ch, and the remaining capacity Cr1 of the first storage battery B1 is equal to or less than the first threshold value Cr1th, and the remaining capacity Cr2 of the second storage battery B2 is greater than the second threshold value Cr2th, that is, when the first storage battery B1 needs to be charged and the remaining capacity Cr2 of the second storage battery B2 has some margin, the power supply unit 3 supplies not only the power supplied from the system power source SP but also the power supplied from the second storage battery B2 to the first storage battery B1 (power supply mode M3). This allows not only the power supplied from the system power source SP but also the power supplied from the second storage battery B2 to be supplied to the first storage battery B1, thereby making it possible to relatively shorten the time required to fully charge the first storage battery B1.

[0049] For example, when executing the power supply mode M3, the power supply unit 3 turns on the switches SW1 to SW3 and turns off the switch SW4, and then repeatedly turns off the switches SW1, SW2, and SW4 and turns on the switch SW3, thereby allowing the power supplied from the system power supply SP and the power supplied from the second storage battery B2 to be supplied to the first storage battery B1.

[0050] FIG. 3 is a flowchart showing an example of the operation of the control unit Cnt.

[0051] First, the connection determination unit 1 determines whether or not the first storage battery B1 is connected to the charger Ch (step S101).

[0052] Next, if it is determined that the first storage battery B1 is connected to the charger Ch (step S101: Yes), and if the remaining capacity Cr1 acquired by the remaining capacity acquisition unit 2 is equal to or less than the first threshold Cr1th (step S102: Yes), and if the remaining capacity Cr2 acquired by the remaining capacity acquisition unit 2 is equal to or less than the second threshold Cr2th (step S103: Yes), the power supply unit 3 executes the power supply mode M1 (step S104).

[0053] In addition, the power supply unit 3 executes the power supply mode M2 ​​(step S106) when it is determined that the first storage battery B1 is not connected to the charger Ch (step S101: No) and the remaining capacity Cr2 acquired by the remaining capacity acquisition unit 2 is equal to or less than the second threshold value Cr2th (step S105: Yes), or when it is determined that the first storage battery B1 is connected to the charger Ch (step S101: Yes) and the remaining capacity Cr1 acquired by the remaining capacity acquisition unit 2 is greater than the first threshold value Cr1th (step S102: No) and the remaining capacity Cr2 acquired by the remaining capacity acquisition unit 2 is equal to or less than the second threshold value Cr2th (step S105: Yes).

[0054] Furthermore, if it is determined that the first storage battery B1 is connected to the charger Ch (step S101: Yes), and if the remaining capacity Cr1 acquired by the remaining capacity acquisition unit 2 is equal to or less than the first threshold value Cr1th (step S102: Yes), and if the remaining capacity Cr2 acquired by the remaining capacity acquisition unit 2 is greater than the second threshold value Cr2th (step S103: No), the power supply unit 3 executes the power supply mode M3 (step S107).

[0055] In addition, if it is determined that the first storage battery B1 is not connected to the charger Ch (step S101: No) and the remaining capacity Cr2 acquired by the remaining capacity acquisition unit 2 is greater than the second threshold value Cr2th (step S105: No), the power supply unit 3 does not supply power to the first storage battery B1 and the second storage battery B2.

[0056] For example, it is assumed that the rated power of the charger Ch is 12 [kW], the maximum output of the system power supply SP is 10 [kW], and the rated power of the second storage battery B2 is 6 [kW].

[0057] In this case, when the power supply unit 3 is operating in the power supply mode M1, it can supply a maximum of 10 kW of power from the charger Ch to the first storage battery B1.

[0058] Furthermore, when the power supply unit 3 is operating in the power supply mode M2, it can supply a maximum of 6 kW of power from the charger Ch to the second storage battery B2.

[0059] Furthermore, when the power supply unit 3 is operating in the power supply mode M3, it can supply a maximum of 12 kW (=10 kW+2 kW) of power from the charger Ch to the first storage battery B1.

[0060] According to the charger Ch of the embodiment, there is no need to provide the charger Ch with a switch for switching between the power supply modes M1 to M3, which can suppress increases in the manufacturing costs of the charger Ch. Furthermore, since the power supply modes M1 to M3 can be automatically switched depending on the connection state between the first storage battery B1 and the charger Ch, the remaining capacity Cr1 of the first storage battery B1, and the remaining capacity Cr2 of the second storage battery B2, it is possible to reduce the effort required by the user when switching between the power supply modes M1 to M3.

[0061] The present invention is not limited to the above-described embodiments, and various improvements and modifications can be made without departing from the spirit and scope of the present invention.

[0062] <Variation 1> Fig. 4 is a diagram showing a modified example of the charger of the embodiment. In Fig. 4, the same components as those shown in Fig. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

[0063] Charger Ch shown in FIG. 4 differs from charger Ch shown in FIG. 1 in that a voltage conversion circuit CVT is connected between charger Ch and second power storage device S2.

[0064] The voltage conversion circuit CVT is, for example, a bidirectional DC-DC converter that converts the output voltage of the charger Ch to a predetermined voltage instructed by the power supply unit 3 and outputs it to the second storage battery B2, or converts the voltage of the second storage battery B2 to a predetermined voltage instructed by the power supply unit 3 and outputs it to the charger Ch.

[0065] That is, when the first storage battery B1 is not connected to the charger Ch and the remaining capacity Cr2 of the second storage battery B2 is equal to or less than the second threshold value Cr2th, or when the first storage battery B1 is connected to the charger Ch and the remaining capacity Cr1 of the first storage battery B1 is greater than the first threshold value Cr1th and the remaining capacity Cr2 of the second storage battery B2 is equal to or less than the second threshold value Cr2th, the power supply unit 3 supplies power supplied from the system power source SP to the second storage battery B2 via the voltage conversion circuit CVT in power supply mode M2.

[0066] In addition, when the first storage battery B1 is connected to the charger Ch, and the remaining capacity Cr1 of the first storage battery B1 is less than or equal to the first threshold value Cr1th, and the remaining capacity Cr2 of the second storage battery B2 is greater than the second threshold value Cr2th, the power supply unit 3 switches to power supply mode M3 and supplies the first storage battery B1 with power supplied from the system power source SP and power supplied from the second storage battery B2 via the voltage conversion circuit CVT.

[0067] According to the charger Ch shown in FIG. 4, the power output from the voltage conversion circuit CVT to the charger Ch can be varied, so that the power supplied from the charger Ch to the first storage battery B1 can be varied, thereby increasing the degree of freedom in the power supply from the charger Ch to the first storage battery B1.

[0068] <Variation 2> Fig. 5 is a flowchart showing a modified example of the operation of control unit Cnt. It is assumed that a voltage conversion circuit CVT is connected between charger Ch and second power storage device S2 as shown in Fig. 4. Steps S101 to S107 shown in Fig. 5 are the same as steps S101 to S107 shown in Fig. 3.

[0069] If the first storage battery B1 is connected to the charger Ch (step S101: Yes), and the remaining capacity Cr1 of the first storage battery B1 is less than or equal to the first threshold Cr1th (step S102: Yes), and the remaining capacity Cr2 of the second storage battery B2 is greater than the second threshold Cr2th (step S103: No), and a power source other than the grid power source SP (such as a solar power generation system or a wind power generation system) is connected to the second storage battery B2 (step S108: Yes), the power supply unit 3 changes the output voltage of the voltage conversion circuit CVT according to the type of power source other than the grid power source SP (step S109) and executes the power supply mode M3 (step S107).

[0070] As a result, when a power source other than the system power source SP is connected to the second storage battery B2, the power supplied from the second storage battery B2 to the charger Ch can be increased and the power supplied from the system power source SP to the charger Ch can be decreased compared to when a power source other than the system power source SP is not connected to the second storage battery B2.This makes it possible to reduce the power consumption of the system power source SP while preventing the second storage battery B2 from entering an over-discharge state.

[0071] Furthermore, when the output power of the solar power generation system is greater than the output power of the wind power generation system, the output voltage of the voltage conversion circuit CVT when the solar power generation system is connected to the second storage battery B2 can be made greater than the output voltage of the voltage conversion circuit CVT when the wind power generation system is connected to the second storage battery B2, thereby reducing the power consumption of the system power supply SP while further preventing the second storage battery B2 from entering an over-discharge state.

[0072] In addition, if the first storage battery B1 is connected to the charger Ch (step S101: Yes), and the remaining capacity Cr1 of the first storage battery B1 is less than or equal to the first threshold Cr1th (step S102: Yes), and the remaining capacity Cr2 of the second storage battery B2 is greater than the second threshold Cr2th (step S103: No), and no power source other than the system power source SP is connected to the second storage battery B2 (step S108: No), the power supply unit 3 does not change the output voltage of the voltage conversion circuit CVT and executes the power supply mode M3 (step S107). [Explanation of symbols]

[0073] Ch charger S1 First power storage device S2 2nd power storage device SP grid power supply CVT voltage conversion circuit 1 Connection determination section 2 Remaining capacity acquisition section 3 Power supply section

Claims

[Claim 1] A charger that supplies power supplied from a system power supply to a first storage battery or a second storage battery, a connection determination unit that determines whether the first storage battery is connected to the charger; a remaining capacity acquisition unit that acquires remaining capacities of the first and second storage batteries; a power supply unit that supplies power to the first storage battery or the second storage battery based on a connection determination result by the connection determination unit and the remaining capacities of the first and second storage batteries acquired by the remaining capacity acquisition unit; Equipped with The power supply unit supplying power from the system power supply to the first storage battery when the first storage battery is connected to the charger, the remaining capacity of the first storage battery is equal to or less than a first threshold, and the remaining capacity of the second storage battery is equal to or less than a second threshold; supplying power from the system power supply to the second storage battery via a voltage conversion circuit when the first storage battery is not connected to the charger and the remaining capacity of the second storage battery is equal to or less than the second threshold, or when the first storage battery is connected to the charger and the remaining capacity of the first storage battery is greater than the first threshold and the remaining capacity of the second storage battery is equal to or less than the second threshold; When the first storage battery is connected to the charger, the remaining capacity of the first storage battery is equal to or less than the first threshold, the remaining capacity of the second storage battery is greater than the second threshold, and a power source other than the system power source is connected to the second storage battery, power from the system power source and power supplied from the second storage battery via the voltage conversion circuit are supplied to the first storage battery, and the output voltage of the voltage conversion circuit is changed depending on the type of the power source other than the system power source. A charger characterized by:

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