Power System

Abstract

The present invention provides a power supply system capable of appropriately suppressing the degradation of a battery. The power supply system includes: a switching unit, which is arranged between a power receiving unit and a load and a battery, and disconnects or connects the electrical connection between the power receiving unit and the load and the battery; when the power receiving unit is capable of receiving power, a load driving mode that allows the load to be driven can be executed; in the load driving mode, during a period in which it is determined that the output power of the power receiving unit is below a reference power, the electrical connection state of the power supply system is set to a first connection state in which the power receiving unit and the load and the battery are electrically disconnected by the switching unit, and the voltage of the power receiving unit is controlled within a reference range corresponding to the voltage of the battery; when it is determined that the output power of the power receiving unit exceeds the reference power, the electrical connection state of the power supply system is set to a second connection state in which the power receiving unit and the load and the battery are connected in a manner that power can be supplied via the switching unit.

Description

Technical Field

[0001] The invention relates to a power supply system. Background Art

[0002] In recent years, electric vehicles such as electric vehicles (EVs) and hybrid electric vehicles (HEVs) that have a driving motor that outputs power to be transmitted to driving wheels have been used. These vehicles are provided with a battery that stores power provided to the driving motor, and the battery can be charged using an external power source. For example, as disclosed in Patent Document 1, a power receiving unit that can receive external power transmitted from an external power source is provided in the vehicle, and the external power is supplied from the power receiving unit to the battery, thereby charging the battery.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-199920 Summary of the invention

[0006] Technical issues

[0007] However, in a vehicle that charges the battery using external power, there is a vehicle that can execute a load drive mode that allows the load connected to the power receiving unit in parallel with the battery to be driven while the power receiving unit can receive power. However, in the load drive mode, the power stored in the battery is sometimes used to drive the load. If the battery is discharged in this way, the remaining capacity of the battery decreases, so charging the battery is considered. Therefore, since the battery is repeatedly charged and discharged in the load drive mode, it is possible that the battery deteriorates.

[0008] Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a new and improved power supply system capable of appropriately suppressing the degradation of a battery.

[0009] Technical Solution

[0010] In order to solve the above-mentioned problems, a power supply system is provided, which includes: a battery for storing electric power supplied to a driving motor, the driving motor outputting power transmitted to a driving wheel; a power receiving unit connected to the battery and capable of receiving external electric power transmitted from an external power source; a load connected to the power receiving unit in parallel with the battery; a switching unit provided between the power receiving unit, the load and the battery, and disconnecting or connecting the electric connection between the power receiving unit, the load and the battery; and a control device including a control unit capable of executing a load driving mode that allows the load to be driven when the power receiving unit is capable of receiving electric power. , the control unit, in the load driving mode, controls the voltage of the power receiving unit within a reference range corresponding to the voltage of the battery, while setting the electrical connection state of the power supply system to a first connection state in which the power receiving unit, the load, and the battery are electrically disconnected by the switching unit, when it is determined that the output power of the power receiving unit is less than the reference power. When it is determined that the output power of the power receiving unit exceeds the reference power, the control unit sets the electrical connection state of the power supply system to a second connection state in which the power receiving unit, the load, and the battery are connected in a manner that power can be supplied via the switching unit.

[0011] The control unit may determine the reference range based on a withstand voltage of the switching unit and a power line connected to the switching unit.

[0012] The control unit may determine the withstand voltage based on temperatures of the switching unit and the power line.

[0013] The control portion may determine the reference range based on a maximum allowable charge and discharge power of the battery.

[0014] The control portion may determine the maximum allowable charge and discharge power based on a temperature of the battery.

[0015] The control section may determine the maximum allowable charge and discharge power based on a remaining capacity of the battery.

[0016] The control unit may maintain the electrical connection state of the power supply system in the second connection state regardless of output power of the power receiving unit during a period from when the electrical connection state of the power supply system is set to the second connection state until a reference time elapses in the load driving mode.

[0017] The control unit may maintain the electrical connection state of the power supply system in the second connection state regardless of the output power of the power receiving unit in the load driving mode after the electrical connection state of the power supply system is set to the second connection state until the remaining capacity of the battery reaches a reference remaining capacity.

[0018] The control unit may control the voltage of the power receiving unit by giving priority to power efficiency when it is determined that the output power of the power receiving unit is equal to or smaller than a first threshold value that is lower than the reference power in the load drive mode.

[0019] The switching unit may include a positive-side relay connected to the positive side of the battery and a negative-side relay connected to the negative side of the battery. In the load driving mode, the control unit may, when it is determined that the output power of the power receiving unit is less than the reference power and greater than a second threshold value greater than the first threshold value, control the voltage of the power receiving unit within the reference range corresponding to the voltage of the battery on the basis of setting the electrical connection state of the power supply system to a third connection state in which one of the positive-side relay and the negative-side relay is disconnected and the other is closed.

[0020] The control unit may close a relay that was opened in the last third connection state and open a relay that was closed in the last third connection state when switching the electrical connection state of the power supply system from another connection state different from the third connection state to the third connection state.

[0021] Technical Effects

[0022] As described above, according to the present invention, it is possible to appropriately suppress the degradation of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram showing a schematic configuration of a power supply system according to an embodiment of the present invention.

[0024] Figure 2 This is a block diagram showing an example of the functional configuration of the control device according to this embodiment.

[0025] Figure 3 This is a flowchart showing a first example of the flow of processing performed by the control device according to this embodiment.

[0026] Figure 4 1 is a diagram showing a first connection state among electrical connection states of the power supply system according to the embodiment.

[0027] Figure 5 This is a diagram showing an example of a reference range for voltage control of the power receiving unit in the first connection state.

[0028] Figure 6 is a diagram showing a reference range for voltage control of the power receiving unit in the first connection state. Figure 5 Figures of different examples.

[0029] Figure 71 is a diagram showing a second connection state among the electrical connection states of the power supply system according to the embodiment.

[0030] Figure 8 This is a flowchart showing a second example of the flow of processing performed by the control device according to this embodiment.

[0031] Fig. 9 This is a flowchart showing a third example of the flow of processing performed by the control device according to this embodiment.

[0032] Fig.10 1 is a diagram showing a third connection state among the electrical connection states of the power supply system according to the embodiment.

[0033] Explanation of symbols

[0034] 1: Power system

[0035] 10: Driving motor

[0036] 20: Converter

[0037] 30: Battery

[0038] 40: Receiving unit

[0039] 50: Load

[0040] 60: Switching Department

[0041] 61: Positive side relay

[0042] 62: Negative side relay

[0043] 71: Power receiving sensor

[0044] 72: Battery Sensor

[0045] 73: Switching temperature sensor

[0046] 100: Control device

[0047] 110: Acquisition Department

[0048] 120: Control Department

[0049] 121: Power receiving unit control unit

[0050] 122: Load control unit

[0051] 123: Switching control unit DETAILED DESCRIPTION

[0052] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in this specification and the drawings, components having substantially the same functional structure are denoted by the same reference numerals to omit repeated description.

[0053] <1. Configuration of power supply system>

[0054] Reference Figure 1 and Figure 2 , the configuration of a power supply system 1 according to an embodiment of the present invention will be described.

[0055] Figure 1 It is a schematic diagram showing a schematic configuration of the power supply system 1 .

[0056] The power supply system 1 is specifically a system installed in an electric vehicle such as an electric vehicle (EV) or a hybrid electric vehicle (HEV) to supply power to various devices in the vehicle. It should be noted that the electric vehicle may be any vehicle having a driving motor as a driving source, including railway vehicles.

[0057] like Figure 1 As shown, the power supply system 1 includes a driving motor 10, an inverter 20, a battery 30, a power receiving unit 40, a load 50, a switching unit 60, a power receiving unit sensor 71, a battery sensor 72, a switching unit temperature sensor 73, and a control device 100. A vehicle equipped with the power supply system 1 travels using the driving motor 10 as a driving source.

[0058] The drive motor 10 is a motor that outputs power to be transmitted to the drive wheels, and is specifically a multi-phase AC motor (for example, a three-phase AC motor). The drive motor 10 is connected to the battery 30 via the converter 20, and generates power using the power supplied from the battery 30 via the converter 20. In addition, the drive motor 10 may also function as a generator that regenerates power using the rotational energy of the drive wheels when the vehicle is decelerated.

[0059] The converter 20 is a power converter capable of bidirectionally performing power conversion between direct current and alternating current, and specifically includes a multi-phase bridge circuit. The converter 20 can convert the direct current power supplied from the battery 30 into alternating current power and supply it to the drive motor 10. In addition, the converter 20 can convert the alternating current power obtained by regenerative power generation of the drive motor 10 into direct current power and supply it to the battery 30. The converter 20 is provided with a switching element, and the power conversion of the converter 20 is controlled by controlling the operation of the switching element.

[0060] The battery 30 is a battery that stores electric power to be supplied to the driving motor 10. As the battery 30, for example, a secondary battery such as a lithium ion battery, a lithium ion polymer battery, a nickel hydrogen battery, a nickel cadmium battery, or a lead storage battery is used.

[0061] The power receiving unit 40 is connected to the battery 30 and can receive external power transmitted from an external power source (i.e., an external power source of a vehicle equipped with the power supply system 1). Since the power receiving unit 40 is provided in the power supply system 1, the battery 30 can be charged with external power supplied from the external power source via the power receiving unit 40.

[0062] For example, the power receiving unit 40 can receive power transmitted from the external power source in a state where it is physically connected to the external power source. Specifically, a transformer capable of converting voltage can be provided in the power receiving unit 40, thereby transforming the external power transmitted from the external power source. In addition, a power converter capable of converting AC power into DC power can also be provided in the power receiving unit 40, thereby, when the external power source is an AC power source, the AC external power transmitted from the external power source can be converted into DC power.

[0063] In addition, for example, the power receiving unit 40 may be a device capable of receiving external power transmitted from an external power source in a non-contact manner. In this case, the power receiving unit 40 is specifically provided with a power receiving coil capable of receiving AC external power transmitted from a power transmission coil of an external power source and a power converter capable of converting the external power into DC power. It should be noted that as a method of transmitting power from the power transmission coil to the power receiving coil, for example, a magnetic resonance method or an electromagnetic induction method is used.

[0064] The load 50 is connected to the power receiving unit 40 in parallel with the battery 30. For example, an air conditioner or a car navigation device is an example of the load 50.

[0065] The switch unit 60 is a device that disconnects or connects the electrical connection between the power reception unit 40 and the load 50 and the battery 30 , and is provided between the power reception unit 40 and the load 50 and the battery 30 .

[0066] Specifically, Figure 1 As shown, the switching unit 60 includes a positive electrode side relay 61 connected to the positive electrode side of the battery 30 and a negative electrode side relay 62 connected to the negative electrode side of the battery 30 .

[0067] The power reception unit sensor 71 detects the electrical state quantity of the power reception unit 40 and outputs it to the control device 100. Specifically, the power reception unit sensor 71 detects the voltage and current of the power reception unit 40 as the electrical state quantity of the power reception unit 40.

[0068] The battery sensor 72 detects the state quantity of the battery 30 and outputs it to the control device 100. Specifically, the battery sensor 72 detects the voltage of the battery 30, the remaining capacity (SOC: State Of Charge) of the battery 30, and the temperature of the battery 30 as the state quantity of the battery 30. It should be noted that the battery sensor 72 can also detect other physical quantities that can be substantially converted into the temperature of the battery 30.

[0069] The switch temperature sensor 73 detects the temperature of the switch 60 and the power line connected to the switch 60. The switch temperature sensor 73 may detect other physical quantities that can be substantially converted into the temperature of the switch 60 and the power line connected to the switch 60.

[0070] The control device 100 is composed of a CPU (Central Processing Unit) as a calculation processing device, a ROM (Read Only Memory) as a storage element for storing programs and calculation parameters used by the CPU, and a RAM (Random Access Memory) as a storage element for temporarily storing parameters that change appropriately during the execution of the CPU.

[0071] Furthermore, the control device 100 communicates with each device mounted on the power supply system 1. The communication between the control device 100 and each device is realized by using, for example, CAN (Controller Area Network) communication.

[0072] It should be noted that the functions of the control device 100 of the present embodiment may be at least partially divided among multiple control devices, or multiple functions may be implemented by one control device. In the case where the functions of the control device 100 are at least partially divided among multiple control devices, the multiple control devices may be connected to each other via a communication bus such as CAN.

[0073] like Figure 2 As shown, the control device 100 includes, for example, an acquisition unit 110 and a control unit 120 .

[0074] Acquisition unit 110 acquires various information used in processing by control unit 120, and outputs the acquired information to control unit 120. For example, acquisition unit 110 communicates with power reception unit sensor 71, battery sensor 72, and switching unit temperature sensor 73 to acquire various information output from these sensors.

[0075] The control unit 120 controls the operation of each device of the power supply system 1. For example, the control unit 120 includes a power receiving unit control unit 121, a load control unit 122, and a switching unit control unit 123.

[0076] The power receiving unit control unit 121 controls the operation of the power receiving unit 40. Specifically, the power receiving unit control unit 121 controls the supply of external power to the power supply system 1 by the power receiving unit 40, thereby controlling the voltage of the power receiving unit 40. For example, in the case where the power receiving unit 40 is provided with a power converter capable of converting AC power into DC power, the power receiving unit control unit 121 controls the operation of the power converter, thereby controlling the external power supplied via the power receiving unit 40. In addition, for example, the power receiving unit control unit 121 can control the external power supplied via the power receiving unit 40 by outputting a control command to the external power supply.

[0077] The load control unit 122 controls the operation of the load 50. Specifically, the load control unit 122 drives the load 50 or stops the load 50 by controlling the power supply to the load 50. For example, the load control unit 122 can control the power supply to the load 50 by controlling the operation of a switch (not shown) that can adjust the power supplied to the load 50.

[0078] The switch control unit 123 controls the operation of the switch 60. Specifically, the switch control unit 123 controls the open / close state of each relay of the switch 60 to control the electrical connection state of the power supply system 1.

[0079] Here, the control unit 120 can execute the load driving mode that allows the load 50 to be driven when the power receiving unit 40 can receive power. For example, an input device such as a button for selecting execution and stop of the load driving mode is provided in the vehicle equipped with the power supply system 1, and the driver can select execution and stop of the load driving mode by operating the input device. The control unit 120 executes the load driving mode when the execution of the load driving mode is selected by the driver.

[0080] In the load driving mode, for example, the load 50 can be driven by external power supplied via the power receiving unit 40. However, in the load driving mode, the power stored in the battery 30 is sometimes used to drive the load 50. If the battery 30 is discharged in this way, the remaining capacity of the battery 30 decreases, so it is considered to charge the battery 30. Therefore, in the prior art, since the battery 30 is repeatedly charged and discharged in the load driving mode, the degradation of the battery 30 may be accelerated.

[0081] Therefore, in the power supply system 1 of the present embodiment, in order to solve the above-mentioned problem, the control unit 120, in the load driving mode, controls the voltage of the power receiving unit 40 to be within the reference range corresponding to the voltage of the battery 30 while setting the electrical connection state of the power supply system 1 to the first connection state, and, on the other hand, when it is determined that the output power of the power receiving unit 40 exceeds the reference power, sets the electrical connection state of the power supply system 1 to the second connection state, wherein the first connection state is a connection state in which the power receiving unit 40 and the load 50 are electrically disconnected from the battery 30 by the switching unit 60, and the second connection state is a connection state in which the power receiving unit 40 and the load 50 are electrically connected to the battery 30 via the switching unit 60. Thus, the deterioration of the battery 30 can be appropriately suppressed. The processing related to the control of the electrical connection state of the power supply system 1 during the execution of the load driving mode by the control unit 120 will be described in detail later.

[0082] <2. Operation of the power supply system>

[0083] Next, refer to Figures 3 to 10 The operation of the power supply system 1 according to the embodiment of the present invention will be described. It should be noted that, hereinafter, as an example of the flow of the process performed by the control device 100, a first example, a second example, and a third example will be described in this order.

[0084] [2-1. First example]

[0085] First, refer to Figure 3 to Figure 7 , a first example of the process flow of the processing performed by the control device 100 is described.

[0086] Figure 3 1 is a flowchart showing a first example of the flow of processing performed by the control device 100 . Figure 3 The control flow shown is specifically repeatedly executed by the control unit 120 during the execution of the load driving mode.

[0087] if Figure 3 The control flow shown in FIG. 1 starts. First, in step S501, the control unit 120 determines whether the output power of the power receiving unit 40 exceeds the reference power. If it is determined that the output power of the power receiving unit 40 is less than the reference power (step S501 / No), the process proceeds to step S502. On the other hand, if it is determined that the output power of the power receiving unit 40 exceeds the reference power (step S501 / Yes), the process proceeds to step S504.

[0088] The output power of power reception unit 40 is power output by power reception unit 40 , and control unit 120 can calculate the output power of power reception unit 40 based on the voltage and current of power reception unit 40 detected by power reception unit sensor 71 , for example.

[0089] Specifically, the reference power corresponds to the upper limit value of the range of power that is allowed to be continuously output from power reception unit 40 .

[0090] It should be noted that in step S501, the control unit 120 may determine as yes when it is predicted that the output power of the power receiving unit 40 exceeds the reference power, in addition to determining as yes when the output power of the power receiving unit 40 actually exceeds the reference power. For example, the control unit 120 can predict that the output power of the power receiving unit 40 exceeds the reference power based on the output power history of the power receiving unit 40 and the change in the power consumption of the load 50.

[0091] When the determination result in step S501 is NO, in step S502 , the control unit 120 sets the electrical connection state of the power supply system 1 to the first connection state.

[0092] Below, refer to Figure 4 The first connection state is described. Figure 4 1 is a diagram showing a first connection state among the electrical connection states of the power supply system 1. Figure 4 In the figure, for easy understanding, illustration of each sensor and control device 100 is omitted.

[0093] like Figure 4 As shown, the first connection state is a connection state in which the power receiving unit 40 and the load 50 are electrically disconnected from the battery 30 by the switching unit 60. Specifically, in the first connection state, the positive electrode side relay 61 and the negative electrode side relay 62 are both opened and closed.

[0094] like Figure 4 As shown by arrow F1 in the figure, in the first connection state, power is supplied from the power receiving unit 40 to the load 50. In addition, in the first connection state, since the power receiving unit 40 and the load 50 are electrically disconnected from the battery 30 by the switching unit 60, power is not supplied between the load 50 and the battery 30. As a result, the input and output currents of the battery 30 can be suppressed, and therefore, the deterioration of the battery 30 caused by repeated charging and discharging of the battery 30 can be suppressed.

[0095] Next, in step S503 , the control unit 120 controls the voltage of the power receiving unit 40 to fall within a reference range corresponding to the voltage of the battery 30 .

[0096] Specifically, by suppressing the voltage on the load 50 side relative to the switching unit 60 (for example, Figure 4 The voltage at the point P1 at which the switching unit 60 is connected is the voltage at the battery 30 side (for example, Figure 4The reference range is determined so that the difference between the voltage at point P2 of the switching unit 60 and the voltage at point P3 of the switching unit 60 becomes too large, thereby controlling the voltage of the power receiving unit 40. By suppressing the voltage difference between the load 50 side relative to the switching unit 60 and the battery 30 side relative to the switching unit 60 from becoming too large, when the power receiving unit 40 and the load 50 are connected to the battery 30 so that power can be supplied via the switching unit 60 (specifically, when each relay of the switching unit 60 is closed) due to the electrical connection state of the power supply system 1 being changed to the second connection state described later, damage to each device can be suppressed.

[0097] More specifically, from the viewpoint of appropriately suppressing damage to the switch unit 60 and the power line connected to the switch unit 60 (hereinafter, also referred to as the switch unit 60, etc.), the control unit 120 preferably determines the reference range based on the withstand voltage of the switch unit 60, etc. as described later. In addition, from the viewpoint of appropriately suppressing damage to the battery 30, the control unit 120 preferably determines the reference range based on the maximum allowable charge and discharge power of the battery 30 as described later.

[0098] Below, refer to Figure 5 , a reference range for controlling the voltage of the power receiving unit 40 in the first connection state will be described. Figure 5 It is a diagram showing an example of a reference range.

[0099] For example, Figure 5 As shown, the control unit 120 determines the upper limit voltage Vmax_re and the lower limit voltage Vmin_re for the switching unit 60 for suppressing damage to the switching unit 60 and the like, and the upper limit voltage Vmax_ba and the lower limit voltage Vmin_ba for the battery 30 for suppressing damage to the battery 30, based on the voltage Vba of the battery 30. Furthermore, the control unit 120 determines the reference range R1 using the upper limit voltage Vmax_re and the lower limit voltage Vmin_re for the switching unit 60 and the upper limit voltage Vmax_ba and the lower limit voltage Vmin_ba for the battery 30.

[0100] The control unit 120 may determine the reference range using only the upper limit voltage Vmax_re and the lower limit voltage Vmin_re for the switching unit 60 , or may determine the reference range using only the upper limit voltage Vmax_ba and the lower limit voltage Vmin_ba for the battery 30 .

[0101] If the voltage of the power receiving unit 40 is too high or too low relative to the voltage Vba of the battery 30, Figure 4When the difference between the voltage at point P1 and the voltage at point P2 becomes too large and the electrical connection state of the power supply system 1 is set to the second connection state, the voltage applied to the switching unit 60, etc. may exceed the withstand voltage of the switching unit 60, etc. and damage the switching unit 60, etc. (for example, the relay melts and sticks). As the upper limit value and lower limit value of the voltage of the power receiving unit 40 to suppress such damage to the switching unit 60, etc., the control unit 120 determines the upper limit voltage Vmax_re and the lower limit voltage Vmin_re for the switching unit 60 based on the voltage Vba of the battery 30 and the withstand voltage of the switching unit 60, etc.

[0102] If the voltage of the power receiving unit 40 is too high relative to the voltage Vba of the battery 30, Figure 4 If the voltage at point P1 becomes too large relative to the voltage at point P2 and the electrical connection state of the power supply system 1 is set to the second connection state, the power charged into the battery 30 may exceed the maximum allowable charging power of the battery 30 (i.e., the amount of power that can be charged into the battery 30 per unit time) and damage the battery 30. On the other hand, if the voltage of the power receiving unit 40 is too low relative to the voltage Vba of the battery 30, Figure 4 When the voltage at point P1 becomes relatively too small relative to the voltage at point P2 and the electrical connection state of the power supply system 1 is set to the second connection state, the power discharged from the battery 30 may exceed the maximum allowable discharge power of the battery 30 (that is, the amount of power that can be discharged by the battery 30 per unit time) and damage the battery 30. As the upper limit value and the lower limit value of the voltage of the power receiving unit 40 to suppress such damage to the battery 30, the control unit 120 determines the upper limit voltage Vmax_ba and the lower limit voltage Vmin_ba for the battery 30 based on the voltage Vba of the battery 30 and the maximum allowable charge and discharge power of the battery 30.

[0103] Furthermore, the control unit 120 determines the lower upper limit voltage of the upper limit voltage Vmax_re for the switching unit 60 and the upper limit voltage Vmax_ba for the battery 30 as the upper limit value of the reference range R1, and determines the higher lower limit voltage of the lower limit voltage Vmin_re for the switching unit 60 and the lower limit voltage Vmin_ba for the battery 30 as the lower limit value of the reference range R1. Figure 5 , the upper limit voltage Vmax_ba for the battery 30 is lower than the upper limit voltage Vmax_re for the switching unit 60, and the lower limit voltage Vmin_re for the switching unit 60 is higher than the lower limit voltage Vmin_ba for the battery 30. Therefore, in this case, Figure 5 As shown, the upper limit value of the reference range R1 is the upper limit voltage Vmax_ba for the battery 30 , and the lower limit value of the reference range R1 is the lower limit voltage Vmin_re for the switching unit 60 .

[0104] For example, when the output power of the power receiving unit 40 increases with the increase in the power consumption of the load 50, Figure 5 As shown by the two-dot chain line in FIG. 1 , the voltage of the power receiving unit 40 gradually decreases. Therefore, if the voltage of the power receiving unit 40 is not controlled within the reference range R1, as shown in FIG. Figure 5 As shown by the two-dot chain line, a state occurs in which the voltage of the power receiving unit 40 is lower than the lower limit voltage Vmin_re for the switching unit 60. When the electrical connection state of the power supply system 1 is set to the second connection state under such a condition, the voltage applied to the switching unit 60, etc. may exceed the withstand voltage of the switching unit 60, etc., and the switching unit 60, etc. may be damaged (for example, the relay may be melted and stuck).

[0105] On the other hand, in the power supply system 1 of the present embodiment, when the electrical connection state of the power supply system 1 is set to the first connection state, the control unit 120 controls the voltage of the power receiving unit 40 to be within the reference range R1 corresponding to the voltage of the battery 30. Therefore, since the voltage difference between the load 50 side with respect to the switching unit 60 and the battery 30 side with respect to the switching unit 60 can be suppressed from becoming excessively large, when the electrical connection state of the power supply system 1 is set to the second connection state, damage to each device can be suppressed.

[0106] Here, since the withstand voltage of the switch unit 60 and the like changes according to the change in the temperature of the switch unit 60 and the like, from the viewpoint of more appropriately suppressing damage to the switch unit 60 and the like, it is preferable that the control unit 120 determines the withstand voltage of the switch unit 60 and the like based on the temperature of the switch unit 60 and the like. Furthermore, since the maximum allowable charge and discharge power of the battery 30 changes according to the change in the temperature or the remaining capacity of the battery 30, from the viewpoint of more appropriately suppressing damage to the battery 30, it is preferable that the control unit 120 determines the maximum allowable charge and discharge power of the battery 30 based on at least one of the temperature of the battery 30 and the remaining capacity.

[0107] As described above, since the withstand voltage of the switching unit 60 and the maximum allowable charge and discharge power of the battery 30 are determined by various parameters, the magnitude relationship between the upper limit voltage Vmax_re for the switching unit 60 and the upper limit voltage Vmax_ba for the battery 30 and the magnitude relationship between the lower limit voltage Vmin_re for the switching unit 60 and the lower limit voltage Vmin_ba for the battery 30 may change. Figure 5 Compared with the example shown in FIG. 1 , when the remaining capacity of the battery 30 is small, as shown in FIG. Figure 6 As shown in FIG. 1 , the upper limit voltage Vmax_ba and the lower limit voltage Vmin_ba for the battery 30 become higher. Figure 6As shown in FIG. 1 , there is a case where the upper limit voltage Vmax_ba and the lower limit voltage Vmin_ba for the battery 30 become higher than the upper limit voltage Vmax_re and the lower limit voltage Vmin_re for the switching unit 60. In this case, Figure 6 As shown, the upper limit value of the reference range R1 ′ is the upper limit voltage Vmax_re for the switching unit 60 , and the lower limit value of the reference range R1 ′ is the lower limit voltage Vmin_ba for the battery 30 .

[0108] It should be noted that the control unit 120 can adjust the lower limit value of the reference range for voltage control of the power receiving unit 40 in the first connection state according to the amount of voltage drop of the power receiving unit 40 when the load that is not currently driven (i.e., the load that may be driven later) among the loads 50 is driven later. For example, the control unit 120 can determine a value that is higher than the lower limit voltage Vmin_re for the switching unit 60 and the lower limit voltage Vmin_ba for the battery 30 by the above-mentioned amount of drop as the lower limit value of the reference range for voltage control of the power receiving unit 40 in the first connection state. In this way, it is possible to appropriately suppress the situation in which the various devices of the power supply system 1 (specifically, the switching unit 60, etc., the battery 30) are damaged due to the load that is not currently driven among the loads 50 being driven later.

[0109] When the determination in step S501 is YES, in step S504 , the control unit 120 sets the electrical connection state of the power supply system 1 to the second connection state.

[0110] Below, refer to Figure 7 , describe the second connection state. Figure 7 1 is a diagram showing a second connection state among the electrical connection states of the power supply system 1. Figure 7 In the figure, for ease of understanding, illustration of each sensor and control device 100 is omitted.

[0111] like Figure 7 As shown, the second connection state is a connection state in which the power receiving unit 40 and the load 50 are connected to the battery 30 in a manner that can supply power via the switching unit 60. Specifically, in the second connection state, the opening and closing states of the positive side relay 61 and the negative side relay 62 are both in the closed state. Therefore, when the control unit 120 determines that the output power of the power receiving unit 40 exceeds the reference power, it is possible to set the electrical connection state of the power supply system 1 to the second connection state by closing each relay of the switching unit 60 (that is, the positive side relay 61 and the negative side relay 62).

[0112] In the second connection state, similarly to the first connection state, Figure 7As shown by arrow F1, power is supplied from the power receiving unit 40 to the load 50. In the second connection state, since the power receiving unit 40 and the load 50 are connected to the battery 30 so as to be able to supply power via the switching unit 60, Figure 7 As shown by arrow F2, power can be supplied from the battery 30 to the load 50 via the switching unit 60. Here, the case where the output power of the power receiving unit 40 exceeds the reference power corresponds to a case where it is difficult to supply the power consumption of the load 50 only by the output power of the power receiving unit 40. Therefore, in such a case, by supplying power from the battery 30 to the load 50, it is possible to suppress the situation where the power supplied to the load 50 is insufficient.

[0113] After step S503 or step S504, end Figure 3 The control flow shown.

[0114] As mentioned above, in Figure 3 In the control flow shown, the electrical connection state of the power supply system 1 can be switched to the first connection state and the second connection state in sequence while the output power of the power receiving unit 40 is increasing. Furthermore, before the electrical connection state of the power supply system 1 is set to the second connection state, the voltage of the power receiving unit 40 is controlled within a reference range corresponding to the voltage of the battery 30 on the basis of the electrical connection state of the power supply system 1 being in the first connection state, thereby preventing the voltage difference between the load 50 side relative to the switching unit 60 and the battery 30 side relative to the switching unit 60 from becoming excessively large. Therefore, when the electrical connection state of the power supply system 1 is set to the second connection state, damage to each device of the power supply system 1 (specifically, the switching unit 60, etc., and the battery 30) can be prevented.

[0115] It should be noted that, in the above description, the example of switching the electrical connection state of the power supply system 1 according to the output power of the power receiving unit 40 in the load driving mode is used for explanation, but the control unit 120 can also use other triggers other than the output power of the power receiving unit 40 to switch the electrical connection state of the power supply system 1.

[0116] For example, from the viewpoint of suppressing wear caused by the opening and closing operation of the relay of the switching unit 60, it is preferable that the control unit 120 maintains the electrical connection state of the power supply system 1 in the second connection state in the load driving mode until the reference time elapses after the electrical connection state of the power supply system 1 is set to the second connection state, regardless of the output power of the power receiving unit 40. The reference time is appropriately set to a value that can appropriately suppress the opening and closing operation of the relay of the switching unit 60 from being performed too frequently.

[0117] Furthermore, for example, from the viewpoint of suppressing a decrease in the remaining capacity of the battery 30, it is preferable that the control unit 120 maintains the electrical connection state of the power supply system 1 in the second connection state in the load driving mode until the remaining capacity of the battery 30 reaches the reference remaining capacity, regardless of the output power of the power receiving unit 40. The reference remaining capacity is appropriately set to a value that can appropriately determine whether the battery 30 is sufficiently charged.

[0118] [2-2. Second example]

[0119] Next, refer to Figure 8 , a second example of the process flow performed by the control device 100 is described.

[0120] Figure 8 : is a flowchart showing a second example of the flow of processing performed by the control device 100 . Figure 8 The control flow shown is specific to Figure 3 The control flow shown is also repeatedly executed by the control unit 120 during the execution of the load driving mode.

[0121] The second example is different from the first example in that, when it is determined that the output power of the power receiving unit 40 is equal to or less than the reference power (step S501 / No), the process of step S601 is performed following step S502 .

[0122] exist Figure 8 In the control flow of the second example shown in FIG. 1 , if the determination in step S501 is negative, Figure 3 Similarly to the control flow of the first example shown in FIG. 1 , in step S502, the control unit 120 sets the electrical connection state of the power supply system 1 to the first connection state. Figure 3 The control flow of the first example shown is different and proceeds to step S601.

[0123] In step S601, the control unit 120 determines whether the output power of the power receiving unit 40 is less than or equal to a first threshold value that is less than the reference power. If it is determined that the output power of the power receiving unit 40 is less than or equal to the first threshold value (step S601 / Yes), the process proceeds to step S602. On the other hand, if it is determined that the output power of the power receiving unit 40 is greater than the first threshold value (step S601 / No), the process proceeds to step S503.

[0124] When the determination in step S601 is YES, in step S602 , control unit 120 controls the voltage of power reception unit 40 with priority given to power efficiency.

[0125] Here, control unit 120 controls the voltage of power reception unit 40 so as to improve power efficiency, and therefore allows the voltage of power reception unit 40 to be outside the reference range used in step S503. This can improve power efficiency in power supply within power supply system 1.

[0126] After step S503, step S504 or step S602, end Figure 8 The control flow shown.

[0127] As mentioned above, in Figure 8 In the control flow shown, in the process of increasing the output power of the power receiving unit 40, the state of the power supply system 1 can be switched in sequence to: a state in which the voltage of the power receiving unit 40 is controlled with priority to power efficiency based on the electrical connection state being in the first connection state, a state in which the voltage of the power receiving unit 40 is controlled within a reference range based on the electrical connection state being in the first connection state, and a state in which the electrical connection state is in the second connection state. Therefore, when the output power of the power receiving unit 40 is less than the reference power and less than the first threshold value, the power efficiency in the power supply in the power supply system 1 can be improved by controlling the voltage of the power receiving unit 40 with priority to power efficiency.

[0128] [2-3. The third example]

[0129] Next, refer to Fig. 9 and Fig.10 , a third example of the process flow performed by the control device 100 is described.

[0130] Fig. 9 1 is a flowchart showing a third example of the flow of processing performed by the control device 100 . Fig. 9 The control flow shown is specific to Figure 3 and Figure 8 The control flow shown is also repeatedly executed by the control unit 120 during the execution of the load driving mode.

[0131] The third example is different from the second example in that, when it is determined that the output power of the power receiving unit 40 is equal to or less than the reference power (step S501 / No), the process of step S701 is performed.

[0132] exist Fig. 9 In the control flow of the third example shown in FIG. 1 , if the determination in step S501 is yes, Figure 8 The control flow of the second example shown in FIG. 1 is similar to that of FIG. 5 , and then proceeds to step S504. On the other hand, if the determination result in step S501 is negative, Figure 8 The control flow of the second example shown is different and proceeds to step S701.

[0133] In step S701, the control unit 120 determines whether the output power of the power receiving unit 40 is greater than the second threshold value greater than the first threshold value. When it is determined that the output power of the power receiving unit 40 is less than the second threshold value (step S701 / No), the process proceeds to step S502. On the other hand, when it is determined that the output power of the power receiving unit 40 is greater than the second threshold value (step S701 / Yes), the process proceeds to step S702.

[0134] When the determination in step S701 is YES, in step S702 , the control unit 120 sets the electrical connection state of the power supply system 1 to the third connection state.

[0135] Below, refer to Fig.10 , the third connection state is described. Fig.10 1 is a diagram showing a third connection state among the electrical connection states of the power supply system 1. Fig.10 In the figure, for ease of understanding, illustration of each sensor and control device 100 is omitted.

[0136] like Fig.10 As shown in FIG. 1 , the third connection state is a connection state in which one of the positive-side relay 61 and the negative-side relay 62 is disconnected and the other is closed. Fig.10 , an example is shown in which the opening and closing states of the positive electrode side relay 61 and the negative electrode side relay 62 are in an open state and a closed state, respectively.

[0137] like Fig.10 As shown by arrow F1, in the third connection state, power is supplied from the power receiving unit 40 to the load 50 as in the first connection state. In addition, in the third connection state, since one of the positive electrode side relay 61 and the negative electrode side relay 62 is disconnected, power is not supplied between the load 50 and the battery 30. Thus, as in the first connection state, the input and output currents of the battery 30 can be suppressed, and therefore, the deterioration of the battery 30 caused by repeated charging and discharging of the battery 30 can be suppressed.

[0138] Following step S702 , the process proceeds to step S503 , in which the control unit 120 controls the voltage of the power receiving unit 40 to be within a reference range corresponding to the voltage of the battery 30 .

[0139] Next, end Fig. 9 The control flow shown.

[0140] As mentioned above, in Fig. 9In the control flow shown, during the process of increasing the output power of the power receiving unit 40, the state of the power supply system 1 can be switched in sequence to: a state in which the voltage of the power receiving unit 40 is controlled with priority to power efficiency based on the electrical connection state being in the first connection state, a state in which the voltage of the power receiving unit 40 is controlled within a reference range based on the electrical connection state being in the first connection state, a state in which the voltage of the power receiving unit 40 is controlled within a reference range based on the electrical connection state being in the third connection state, and a state in which the electrical connection state is in the second connection state. Therefore, since the opening and closing state of the other relay of the positive side relay 61 and the negative side relay 62 can be set to a closed state by setting the electrical connection state of the power supply system 1 to the third connection state before setting the electrical connection state of the power supply system 1 to the second connection state, the electrical connection state of the power supply system 1 can be set to the second connection state by closing only one of the positive side relay 61 and the negative side relay 62. As a result, the electrical connection state of the power supply system 1 can be quickly switched.

[0141] Here, from the viewpoint of suppressing wear caused by the opening and closing operation of the relay of the switching unit 60, it is preferred that the control unit 120 closes the relay that was opened in the last third connection state and opens the relay that was closed in the last third connection state when switching the electrical connection state of the power supply system 1 from another connection state different from the third connection state to the third connection state. Fig.10 As shown, in the case where the positive-side relay 61 is disconnected and the negative-side relay 62 is closed in the last third connection state, the control unit 120 closes the positive-side relay 61 and disconnects the negative-side relay 62 when switching the electrical connection state of the power supply system 1 from another connection state different from the third connection state to the third connection state. Furthermore, the control unit 120 disconnects the positive-side relay 61 and closes the negative-side relay 62 when switching from another connection state different from the third connection state to the third connection state next time.

[0142] <3. Effect of power supply system>

[0143] Next, effects of the power supply system 1 according to the embodiment of the present invention will be described.

[0144] In the power supply system 1 of the present embodiment, the control unit 120 can execute a load driving mode that allows the load 50 connected to the power receiving unit 40 in parallel with the battery 30 to be driven in a state where the power receiving unit 40 can receive power. In addition, a switching unit 60 that disconnects or connects the electrical connection between the power receiving unit 40 and the load 50 and the battery 30 is provided between the power receiving unit 40 and the load 50 and the battery 30. In addition, in the load driving mode, the control unit 120 controls the voltage of the power receiving unit 40 within a reference range corresponding to the voltage of the battery 30, while setting the electrical connection state of the power supply system 1 to the first connection state in which the power receiving unit 40 and the load 50 are electrically disconnected from the battery 30 by the switching unit 60, while determining that the output power of the power receiving unit 40 is less than the reference power. On the other hand, in the load driving mode, when the control unit 120 determines that the output power of the power receiving unit 40 exceeds the reference power, the electrical connection state of the power supply system 1 is set to the second connection state in which the power receiving unit 40 and the load 50 are electrically connected to the battery 30 via the switching unit 60.

[0145] Thus, when the power consumption of the load 50 can be supplied only by the output power of the power receiving unit 40, by setting the electrical connection state of the power supply system 1 to the first connection state, the input and output current of the battery 30 can be suppressed, and thus, the deterioration of the battery 30 caused by repeated charging and discharging of the battery 30 can be suppressed. On the other hand, when it is difficult to supply the power consumption of the load 50 only by the output power of the power receiving unit 40, by setting the electrical connection state of the power supply system 1 to the second connection state, the situation where the power supply to the load 50 is insufficient can be suppressed. Furthermore, in the first connection state, since the voltage difference between the load 50 side with respect to the switching unit 60 and the battery 30 side with respect to the switching unit 60 can be suppressed from becoming excessive, when the electrical connection state of the power supply system 1 is set to the second connection state, the damage of each device of the power supply system 1 (specifically, the switching unit 60, etc., the battery 30) can be suppressed. Therefore, the deterioration of the battery 30 can be appropriately suppressed.

[0146] Furthermore, in the power supply system 1 of the present embodiment, it is preferable that the control unit 120 determines the reference range based on the withstand voltage of the switching unit 60 and the power line connected to the switching unit 60. Thus, when the electrical connection state of the power supply system 1 is set to the second connection state, it is possible to suppress the voltage applied to the switching unit 60 and the power line connected to the switching unit 60 from exceeding the withstand voltage of the switching unit 60 and the power line connected to the switching unit 60. Therefore, damage to the switching unit 60 and the power line connected to the switching unit 60 can be appropriately suppressed.

[0147] Furthermore, in the power supply system 1 of the present embodiment, it is preferable that the control unit 120 determines the withstand voltage of the switching unit 60 and the power line connected to the switching unit 60 based on the temperature of the switching unit 60 and the power line connected to the switching unit 60. Thus, the withstand voltage of the switching unit 60 and the power line connected to the switching unit 60 can be appropriately determined according to the change in the temperature of the switching unit 60 and the power line connected to the switching unit 60. Therefore, damage to the switching unit 60 and the power line connected to the switching unit 60 can be more appropriately suppressed.

[0148] Furthermore, in the power supply system 1 of the present embodiment, it is preferred that the control unit 120 determines the reference range based on the maximum allowable charge and discharge power of the battery 30. Thus, when the electrical connection state of the power supply system 1 is set to the second connection state, it is possible to suppress the situation where the power charged into the battery 30 exceeds the maximum allowable charge power of the battery 30 and the situation where the power discharged from the battery 30 exceeds the maximum allowable discharge power of the battery 30. Therefore, damage to the battery 30 can be appropriately suppressed.

[0149] Furthermore, in the power supply system 1 of the present embodiment, the control unit 120 preferably determines the maximum allowable charge and discharge power of the battery 30 based on the temperature of the battery 30. Thus, the maximum allowable charge and discharge power of the battery 30 can be appropriately determined according to the change in the temperature of the battery 30. Therefore, damage to the battery 30 can be more appropriately suppressed.

[0150] In the power supply system 1 of the present embodiment, the control unit 120 preferably determines the maximum allowable charge and discharge power of the battery 30 based on the remaining capacity of the battery 30. Thus, the maximum allowable charge and discharge power of the battery 30 can be appropriately determined according to the change in the remaining capacity of the battery 30. Therefore, damage to the battery 30 can be more appropriately suppressed.

[0151] In addition, in the power supply system 1 of the present embodiment, it is preferred that the control unit 120 maintains the electrical connection state of the power supply system 1 in the second connection state in the load drive mode until the reference time has passed after the electrical connection state of the power supply system 1 is set to the second connection state, regardless of the output power of the power receiving unit 40. Thus, it is possible to suppress the situation where the relay of the switching unit 60 is opened and closed too frequently as the electrical connection state of the power supply system 1 is switched too frequently between the first connection state and the second connection state. Therefore, it is possible to suppress wear caused by the opening and closing operation of the relay of the switching unit 60.

[0152] In addition, in the power supply system 1 of the present embodiment, it is preferred that the control unit 120 maintains the electrical connection state of the power supply system 1 in the second connection state in the load driving mode, regardless of the output power of the power receiving unit 40, after the electrical connection state of the power supply system 1 is set to the second connection state until the remaining capacity of the battery 30 reaches the reference remaining capacity. Thus, in the second connection state, the remaining capacity of the battery 30 that has decreased due to the supply of power from the battery 30 to the load 50 can be appropriately restored. That is, the decrease in the remaining capacity of the battery 30 can be suppressed.

[0153] Furthermore, in the power supply system 1 of the present embodiment, it is preferred that the control unit 120, in the load drive mode, when it is determined that the output power of the power receiving unit 40 is less than or equal to a first threshold value that is less than the reference power, controls the voltage of the power receiving unit 40 with priority given to power efficiency. Thus, when the output power of the power receiving unit 40 is less than or equal to the reference power and less than or equal to the first threshold value, the voltage of the power receiving unit 40 is controlled with priority given to power efficiency, thereby making it possible to improve the power efficiency in the power supply within the power supply system 1.

[0154] In the power supply system 1 of the present embodiment, it is preferred that the control unit 120, in the load drive mode, controls the voltage of the power receiving unit 40 within a reference range corresponding to the voltage of the battery 30 after setting the electrical connection state of the power supply system 1 to a third connection state in which one of the positive-side relay 61 and the negative-side relay 62 is opened and the other is closed, when it is determined that the output power of the power receiving unit 40 is less than the reference power and is greater than the second threshold value greater than the first threshold value. Thus, since the opening and closing state of the other of the positive-side relay 61 and the negative-side relay 62 can be set to a closed state by setting the electrical connection state of the power supply system 1 to the third connection state before setting the electrical connection state of the power supply system 1 to the second connection state, the electrical connection state of the power supply system 1 can be set to the second connection state by closing only one of the positive-side relay 61 and the negative-side relay 62. Thus, the electrical connection state of the power supply system 1 can be quickly switched.

[0155] In addition, in the power supply system 1 of the present embodiment, it is preferred that the control unit 120 closes the relay that was opened in the last third connection state and opens the relay that was closed in the last third connection state when switching the electrical connection state of the power supply system 1 from another connection state different from the third connection state to the third connection state. Thus, in the opening and closing of the relay of the switching unit 60 accompanying the switching of the electrical connection state of the power supply system 1, the frequency of the opening and closing operation of one relay of the switching unit 60 can be suppressed from becoming too high compared to the frequency of the opening and closing operation of the other relay. Therefore, wear caused by the opening and closing operation of the relay of the switching unit 60 can be suppressed.

[0156] <4. Conclusion>

[0157] As described above, in the power supply system 1 of the present embodiment, in the load driving mode in which the control unit 120 allows the load 50 connected to the power receiving unit 40 in parallel with the battery 30 to be driven while the power receiving unit 40 is capable of receiving electric power, during a period in which it is determined that the output power of the power receiving unit 40 is less than the reference power, the control unit 120 controls the voltage of the power receiving unit 40 to be within a reference range corresponding to the voltage of the battery 30, while setting the electrical connection state of the power supply system 1 to the first connection state in which the power receiving unit 40 and the load 50 are electrically disconnected from the battery 30 by the switching unit 60, and, when it is determined that the output power of the power receiving unit 40 exceeds the reference power, sets the electrical connection state of the power supply system 1 to the second connection state in which the power receiving unit 40 and the load 50 are electrically connected to the battery 30 via the switching unit 60.

[0158] Thus, when the power consumption of the load 50 can be supplied only by the output power of the power receiving unit 40, by setting the electrical connection state of the power supply system 1 to the first connection state, it is possible to suppress the deterioration of the battery 30. On the other hand, when it is difficult to supply the power consumption of the load 50 only by the output power of the power receiving unit 40, by setting the electrical connection state of the power supply system 1 to the second connection state, it is possible to suppress the situation where the power supply to the load 50 is insufficient. Furthermore, when the electrical connection state of the power supply system 1 is set to the second connection state, it is possible to suppress damage to each device of the power supply system 1. Therefore, it is possible to appropriately suppress the deterioration of the battery 30.

[0159] The preferred embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. Obviously, if a person has common knowledge in the technical field to which the present invention belongs, he or she can think of various variations or modifications within the scope of the technical ideas recorded in the claims, and it should be understood that these variations or modifications also belong to the technical scope of the present invention.

[0160] Specifically, in the above description, reference is made to Figure 1 The power supply system 1 has been described, but Figure 1 The power supply system 1 shown is only an example of the power supply system of the present invention. The power supply system of the present invention can be Figure 1 The power supply system 1 shown is a system in which various modifications such as addition, deletion, or modification of components are appropriately performed.

[0161] For example, in Figure 1 In the figure, the components between the converter 20 and the battery 30 are omitted for ease of understanding, but a converter switching unit for disconnecting and connecting the electrical connection between the converter 20 and the battery 30 may be provided between the converter 20 and the battery 30. Figure 1In the embodiment, the converter 20 and the drive motor 10 are arranged on the battery 30 side relative to the switching unit 60, but the converter 20 and the drive motor 10 may also be arranged on the load 50 side relative to the switching unit 60. In this case, the switching unit 60 can be used to disconnect and connect the electrical connection between the converter 20 and the battery 30, thereby eliminating the necessity of separately providing the switching unit for the converter and the switching unit 60, thereby reducing costs.

[0162] Furthermore, the processing described in the flowcharts in this specification does not necessarily have to be performed in the order shown in the flowcharts. In addition, additional processing steps may be adopted, and some processing steps may be omitted.

Claims

1. A power supply system, characterized in that: include: a battery storing electric power supplied to a driving motor, wherein the driving motor outputs power transmitted to a driving wheel; a power receiving unit connected to the battery and capable of receiving external power transmitted from an external power source; a load connected to the power receiving unit in parallel with the battery; a switching unit provided between the power receiving unit and the load and the battery, and disconnecting or connecting the electrical connection between the power receiving unit and the load and the battery; as well as The control device includes a control unit capable of executing a load driving mode that allows the load to be driven when the power receiving unit is capable of receiving power. The control unit increases the output power of the power receiving unit in the load driving mode as the power consumption of the load increases, controls the voltage of the power receiving unit within a reference range for suppressing damage to the battery and / or the switching unit, which is determined in a manner to suppress the difference between the voltage on the load side with respect to the switching unit and the voltage on the battery side with respect to the switching unit from becoming excessive, while the electrical connection state of the power supply system is set to a first connection state, while it is determined that the output power of the power receiving unit is less than a reference power, and sets the electrical connection state of the power supply system to a second connection state, so that power is supplied from the battery to the load via the switching unit, when it is determined that the output power of the power receiving unit exceeds the reference power and it is difficult to supply the power consumption of the load only with the output power of the power receiving unit. The first connection state is a connection state in which the power receiving unit and the load are electrically disconnected from the battery by the switching unit, and the second connection state is a connection state in which the power receiving unit and the load are connected to the battery via the switching unit so that power supply is possible.

2. The power supply system according to claim 1, characterized in that: The control unit determines the reference range based on the withstand voltage of the switching unit and a power line connected to the switching unit.

3. The power supply system according to claim 2, characterized in that: The control unit determines the withstand voltage based on the switching unit and the temperature of the power line.

4. The power supply system according to any one of claims 1 to 3, characterized in that: The control unit determines the reference range based on a maximum allowable charge and discharge power of the battery.

5. The power supply system according to claim 4, characterized in that: The control unit determines the maximum allowable charge and discharge power based on the temperature of the battery.

6. The power supply system according to claim 4, characterized in that: The control unit determines the maximum allowable charge and discharge power based on the remaining capacity of the battery.

7. The power supply system according to any one of claims 1 to 3, characterized in that: In the load driving mode, the control unit maintains the electrical connection state of the power supply system in the second connection state regardless of output power of the power receiving unit until a reference time elapses after the electrical connection state of the power supply system is set to the second connection state.

8. The power supply system according to any one of claims 1 to 3, characterized in that: In the load driving mode, the control unit maintains the electrical connection state of the power supply system in the second connection state regardless of the output power of the power receiving unit after the electrical connection state of the power supply system is set to the second connection state until the remaining capacity of the battery reaches a reference remaining capacity.

9. The power supply system according to any one of claims 1 to 3, characterized in that: In the load driving mode, the control unit controls the voltage of the power receiving unit with priority given to power efficiency while setting the electrical connection state of the power supply system to the first connection state when it is determined that the output power of the power receiving unit is less than a first threshold value that is less than the reference power, and controls the voltage of the power receiving unit within a reference range corresponding to the voltage of the battery when it is determined that the output power of the power receiving unit is greater than the first threshold value.

10. The power supply system according to claim 9, characterized in that: The switching unit includes a positive-side relay connected to the positive side of the battery and a negative-side relay connected to the negative side of the battery. In the load driving mode, when the control unit determines that the output power of the power receiving unit is lower than the reference power and higher than a second threshold value greater than the first threshold value, the control unit controls the voltage of the power receiving unit within the reference range corresponding to the voltage of the battery on the basis of setting the electrical connection state of the power supply system to a third connection state, wherein the third connection state is a connection state in which one of the positive-side relay and the negative-side relay is disconnected and the other is closed.

11. The power supply system according to claim 10, characterized in that: When switching the electrical connection state of the power supply system from another connection state different from the third connection state to the third connection state, the control unit closes the relay that was opened in the last third connection state and opens the relay that was closed in the last third connection state.

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