阅读说明：本技术 燃料电池车辆的外部供电系统和供电方法 (External power supply system and power supply method for fuel cell vehicle ) 是由 李圭一 朴建炯 于 2018-12-04 设计创作，主要内容包括：提供了一种燃料电池车辆的外部供电系统和供电方法。该系统包括燃料电池、以及经由主总线端子连接到燃料电池的高压电池。充电/放电单元执行高压电池的充电或者放电。供电线路从主总线端子分支并且连接到车辆外部的负载以供应燃料电池或者高压电池的电力到车辆外部的负载。控制器基于供应给车辆外部的负载的功率的大小以及高压电池的电荷状态SOC来操作燃料电池和充电/放电单元。(An external power supply system and a power supply method of a fuel cell vehicle are provided. The system includes a fuel cell, and a high voltage battery connected to the fuel cell via a primary bus terminal. The charging/discharging unit performs charging or discharging of the high-voltage battery. The power supply line branches from the main bus terminal and is connected to a load outside the vehicle to supply electric power of the fuel cell or the high-voltage battery to the load outside the vehicle. The controller operates the fuel cell and the charge/discharge unit based on the magnitude of power supplied to a load outside the vehicle and the state of charge SOC of the high-voltage battery.)

1. An external power supply system of a fuel cell vehicle, comprising:

a fuel cell;

a high voltage battery connected to the fuel cell via a main bus terminal;

a charging/discharging unit configured to perform charging or discharging of the high-voltage battery;

a power supply line that branches from the main bus terminal and is connected to a load outside the vehicle to supply electric power of the fuel cell or the high-voltage battery to the load outside the vehicle; and

a controller configured to operate the fuel cell and the charge/discharge unit based on a magnitude of power supplied to a load outside a vehicle and a state of charge SOC of the high-voltage battery.

2. The external power supply system according to claim 1, wherein the charge/discharge unit is a direct-current DC converter interposed at the main bus terminal between the fuel cell and the high-voltage battery.

3. The external power supply system according to claim 1, wherein the power supply line is connected in parallel between the fuel cell and the charging/discharging unit to supply electric power from the fuel cell or the high-voltage battery to a load outside a vehicle.

4. The external power supply system according to claim 1, wherein the controller is configured to adjust the proportion of the electric power supplied from the fuel cell to increase as the magnitude of the power supplied to the load outside the vehicle increases.

5. The external power supply system according to claim 1, wherein the controller is configured to adjust the proportion of the electric power supplied from the high-voltage battery to increase as the magnitude of the power supplied to the load outside the vehicle decreases.

6. The external power supply system according to claim 1, wherein the controller is configured to divide the control mode into a plurality of control modes based on a magnitude of power supplied to a load outside the vehicle, and in the low power mode among the plurality of control modes, stop operation of the fuel cell and allow only the high-voltage battery to supply electric power to the load outside the vehicle when a state of charge of the high-voltage battery is equal to or greater than a predetermined first SOC.

7. The external power supply system according to claim 6, wherein the controller is configured to enable the high-voltage battery to supply electric power to a load outside the vehicle in a state where the charging/discharging unit suppresses the output voltage of the high-voltage battery from boosting.

8. The external power supply system according to claim 1, wherein the controller is configured to divide the control mode into a plurality of control modes based on a magnitude of power supplied to a load outside the vehicle, and in the low power mode among the plurality of control modes, supply power to the load outside the vehicle while charging the high-voltage battery using the fuel cell when a state of charge of the high-voltage battery is less than a predetermined second SOC.

9. The external power supply system according to claim 1, wherein the controller is configured to divide a control mode into a plurality of control modes based on a magnitude of power supplied to a load external to the vehicle, and operate the charging/discharging unit to suppress charging or discharging of the high-voltage battery when a state of charge of the high-voltage battery is equal to or greater than a predetermined third SOC in an intermediate power mode among the plurality of control modes.

10. The external power supply system according to claim 9, wherein the controller is configured to stop the operation of the fuel cell and allow only the high-voltage battery to supply electric power to a load outside the vehicle when the state of charge of the high-voltage battery is equal to or greater than a predetermined fourth SOC that is greater than the third SOC.

11. The external power supply system according to claim 1, wherein the controller is configured to divide a control mode into a plurality of control modes based on a magnitude of power supplied to a load outside a vehicle, and operate the charging/discharging unit to suppress charging or discharging of the high-voltage battery when a state of charge of the high-voltage battery is less than a fifth SOC in a high-power mode among the plurality of control modes.

12. The external power supply system according to claim 11, wherein the charging unit operates to supply electric power to a load outside the vehicle through the high-voltage battery when the state of charge of the high-voltage battery is equal to or greater than a fifth SOC, and stops the operation of the fuel cell when the magnitude of the power supplied to the load outside the vehicle is less than a preset power value.

13. The external power supply system according to claim 11, wherein the controller is configured to operate the fuel cell to supply electric power to a load outside the vehicle while charging the high-voltage battery when the state of charge of the high-voltage battery is less than a sixth SOC that is less than a fifth SOC.

14. An external power supply method of a fuel cell vehicle, comprising the steps of:

obtaining, by a controller, a magnitude of power to be supplied to a load external to the vehicle;

determining, by the controller, a state of charge of a high voltage battery; and

operating, by the controller, the fuel cell and the direct current DC converter based on the obtained magnitude of power supplied to a load external to the vehicle and the determined state of charge of the high-voltage battery.

15. The external power supply method according to claim 14, wherein in the operations of the fuel cell and the DC converter, the control mode is divided into a plurality of control modes based on a magnitude of power supplied to the load outside the vehicle, and the operations of the fuel cell and the DC converter are adjusted such that a proportion of the power supplied from the fuel cell increases as the magnitude of the power supplied to the load outside the vehicle increases, and a proportion of the power supplied from the high-voltage battery increases as the magnitude of the power supplied to the load outside the vehicle decreases.

16. The external power supply method according to claim 14, further comprising the steps of:

determining, by the controller, a state of the fuel cell after operating the fuel cell and the DC converter; and

operating, by the controller, the fuel cell based on the determined state of the fuel cell.

17. The externally powering method of claim 16, further comprising the step of:

in response to determining that the fuel cell is in the dry-out state in the state where the fuel cell is determined, stopping, by the controller, the operation of the fuel cell and operating the DC converter to suppress the step-up of the output voltage of the high-voltage battery.

18. The externally powering method of claim 16, further comprising the step of:

adjusting, by the controller, air supplied to the fuel cell by adding a preset recovery control current to a required current of the fuel cell in response to determining that the fuel cell is in a filling state.

Technical Field

The present invention relates to an external power supply system and a power supply method of a fuel cell vehicle, and more particularly, to power distribution control based on the magnitude of power supplied to a load outside the vehicle and the state of charge (SOC) of a high-voltage battery.

Background

The fuel cell is an energy conversion device that converts chemical energy of fuel into electrical energy through an electrochemical reaction without converting the chemical energy into heat through combustion, and can be used to supply electric power to industrial, household, and automobile devices, and in addition, can be used to supply electric power to small electric/electronic products and mobile devices. In particular, in a Polymer Electrolyte Membrane Fuel Cell (PEMFC) having high power density, the innermost part of the PEMFC includes a Membrane Electrode Assembly (MEA) which is a main constituent. The membrane electrode assembly includes a polymer electrolyte membrane that can move protons, and a cathode and an anode that are electrode layers coated with a catalyst so that hydrogen and oxygen can react on both surfaces of the electrolyte membrane.

A fuel cell vehicle in which such a fuel cell is mounted on the vehicle uses electric power generated by the fuel cell to drive a motor, thereby obtaining power. However, such a fuel cell vehicle may be utilized as a power supply system that is connected to a load located outside the vehicle and is configured to supply power to the load outside the vehicle. In other words, the fuel cell vehicle may be configured to power a load external to the vehicle as a mobile generator. However, when operating a fuel cell vehicle using such a movable generator, there is a demand for a technique of supplying power to the outside of the vehicle through power distribution control or fuel idle stop control suitable for each situation.

Matters described as related art have been provided only for background to aid in understanding the present invention and should not be construed as corresponding to related art known to those skilled in the art.

Disclosure of Invention

An object of the present invention is to provide an external power supply system and a power supply method of a fuel cell vehicle, which are capable of controlling operations of a fuel cell and a charge/discharge unit based on the magnitude of power supplied to a load outside the vehicle and the state of charge (SOC) of a high-voltage battery.

According to an exemplary embodiment of the present invention, an external power supply system of a fuel cell vehicle may include: a fuel cell; a high voltage battery connected to the fuel cell via a main bus terminal; a charging/discharging unit configured to perform charging or discharging of the high-voltage battery; a power supply line that branches from the main bus terminal and is connected to a load outside the vehicle to supply electric power of the fuel cell or the high-voltage battery to the load outside the vehicle; and a controller configured to operate the fuel cell and the charge/discharge unit based on a magnitude of power supplied to a load outside the vehicle and a state of charge (SOC) of the high-voltage battery.

The charging/discharging unit may be a Direct Current (DC) converter disposed at a main bus terminal between the fuel cell and the high voltage battery. The power supply line may be connected in parallel between the fuel cell and the charging/discharging unit to supply electric power from the fuel cell or the high-voltage battery to a load outside the vehicle. The controller may be configured to adjust the proportion of the electric power supplied from the fuel cell to increase as the magnitude of the power supplied to the load outside the vehicle increases. The controller may be further configured to adjust the proportion of the electric power supplied from the high-voltage battery to increase as the magnitude of the electric power supplied to the load outside the vehicle decreases.

Additionally, the controller may be configured to divide the control mode into a plurality of control modes based on a magnitude of power supplied to a load outside the vehicle, and in a low power mode among the plurality of modes, stop operation of the fuel cell and allow only the high-voltage battery to supply electric power to the load outside the vehicle when a state of charge of the high-voltage battery is equal to or greater than a predetermined first SOC. The controller may be configured to allow the high-voltage battery to supply electric power to a load outside the vehicle when the charging/discharging unit suppresses the output voltage of the high-voltage battery from boosting.

The controller may be configured to divide the control mode into a plurality of control modes based on a magnitude of power supplied to a load outside the vehicle, and in a low power mode among the plurality of modes, supply electric power to the load outside the vehicle while charging the high-voltage battery using the fuel cell when a state of charge of the high-voltage battery is less than a predetermined second SOC. The controller may be further configured to divide the control mode into a plurality of control modes based on a magnitude of power supplied to a load outside the vehicle, and operate the charging/discharging unit to suppress charging or discharging of the high-voltage battery when a state of charge of the high-voltage battery is equal to or greater than a predetermined third SOC in an intermediate power mode among the plurality of modes.

The controller may be configured to stop the operation of the fuel cell and allow only the high-voltage battery to supply electric power to a load outside the vehicle when the state of charge of the high-voltage battery is equal to or greater than a predetermined fourth SOC that is greater than the third SOC. The controller may be further configured to divide the control mode into a plurality of control modes based on a magnitude of power supplied to a load outside the vehicle, and operate the charging/discharging unit to suppress charging or discharging of the high-voltage battery when a state of charge of the high-voltage battery is less than a fifth SOC in a high-power mode among the plurality of modes.

The charging unit may be operable to supply electric power to a load outside the vehicle through the high-voltage battery when the state of charge of the high-voltage battery is equal to or greater than the fifth SOC, and may stop the operation of the fuel cell when the magnitude of the power supplied to the load outside the vehicle is less than a preset power value. The controller may be configured to operate the fuel cell to supply electric power to a load external to the vehicle while charging the high-voltage battery when the state of charge of the high-voltage is less than a sixth SOC, which may be less than the fifth SOC.

According to another exemplary embodiment of the present invention, an external power supply method of a fuel cell vehicle may include: obtaining a magnitude of power to be supplied to a load external to the vehicle; determining a state of charge of the high voltage battery; and operating the fuel cell and the DC converter based on the obtained magnitude of power supplied to a load outside the vehicle and the determined state of charge of the high-voltage battery.

In the operation of the fuel cell and the DC converter, the control mode may be divided into a plurality of control modes based on the magnitude of power supplied to the load outside the vehicle, and the operations of the fuel cell and the DC converter may be adjusted such that the proportion of power supplied from the fuel cell increases as the magnitude of power supplied to the load outside the vehicle increases, and the proportion of power supplied from the high-voltage battery increases as the magnitude of power supplied to the load outside the vehicle decreases.

The external power supply method may further include: determining a state of the fuel cell after operating the fuel cell and the DC converter; and operating the fuel cell based on the determined state of the fuel cell. In response to determining that the fuel cell is in the dry-out state in the determining the state of the fuel cell, the operation of the fuel cell may be stopped and the DC converter may be operated to suppress the step-up of the output voltage of the high-voltage battery. In response to determining that the fuel cell is in the full state when determining the state of the fuel cell, the supply of air to the fuel cell may be adjusted by adding a preset recovery control current to the required current of the fuel cell.

Drawings

The above and other features of the present disclosure will now be described in detail with reference to exemplary implementations of the present disclosure illustrated in the accompanying drawings, where the exemplary embodiments are given below by way of illustration only and thus do not constitute a limitation of the present disclosure, and wherein:

fig. 1 is a configuration diagram of an external power supply system of a fuel cell vehicle according to an exemplary embodiment of the invention;

fig. 2 is a flowchart of an external power supply method of a fuel cell vehicle according to an exemplary embodiment of the invention; and

fig. 3 to 5 are diagrams illustrating the flowchart of fig. 2 in detail, according to an exemplary embodiment of the present invention.

Detailed Description

It is understood that the term "vehicle" or "vehicular" or other similar terms as used herein includes motor vehicles in general, such as passenger cars, including Sport Utility Vehicles (SUVs), buses, trucks, various commercial vehicles; ships, including various watercraft and naval vessels; aircraft, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle having two or more power sources, such as a vehicle having both gasoline power and electric power.

Although the exemplary embodiments are described as using multiple units to perform the exemplary processes, it is understood that the exemplary processes may also be performed by one or more modules. Additionally, it is understood that the term controller/controller refers to a hardware device that includes a memory and a processor. The memory is configured to store modules and the processor is specially configured to execute the modules to perform one or more processes described further below.

Furthermore, the control logic of the present invention may be embodied as a non-transitory computer readable medium on a computer readable medium containing executable program instructions for execution by a processor, controller/controller, or the like. Examples of computer readable media include, but are not limited to, ROM, RAM, Compact Disc (CD) -ROM, magnetic tape, floppy disk, flash drive, smart card, and optical data storage device. The computer readable recording medium CAN also be distributed over network coupled computer systems so that the computer readable medium is stored and executed in a distributed fashion, such as over a telematics server or a Controller Area Network (CAN).

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any of one or more of the associated listed items as well as all combinations of the one or more items.

Unless specifically stated or otherwise evident from the context, as used herein, the term "about" is understood to be within the normal tolerance of the prior art, e.g., within two standard deviations of the mean. "about" can be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the recited value. All numerical values provided herein are modified by the term "about" unless the context clearly dictates otherwise.

The specific structural and functional descriptions in the exemplary embodiments of the present invention disclosed in the present specification or the present application are described to describe exemplary embodiments of the present invention, and thus, the exemplary embodiments of the present invention may be practiced in various forms and are not to be construed as being limited to the exemplary embodiments of the present invention disclosed in the present specification or the present application.

Because exemplary embodiments of the invention can be modified in various ways and can take several forms, specific exemplary embodiments will be shown in the drawings and will be described in detail in this specification or this disclosure. It should be understood, however, that the invention is not limited to the particular exemplary embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Terms such as "first," "second," and the like may be used to describe various components, but the components are not to be construed as limited by the terms. The term is used only to distinguish one component from another. For example, a "first" component may be termed a "second" component and a "second" component may similarly be termed a "first" component without departing from the scope of the present invention.

It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or directly coupled to the other element or be connected or coupled to the other element with the other element intervening therebetween. On the other hand, it will be understood that when an element is referred to as being "directly connected to" or "directly coupled to" another element, it can be connected or coupled to the other element without the other element intervening therebetween. Other expressions describing the relationship between components are namely "between … … and … …", "directly between … … and … …", "adjacent", "directly adjacent", etc. and should be interpreted similarly.

Unless otherwise indicated, it is to be understood that all terms used in the specification include technical and scientific terms and have the same meaning as understood by one of ordinary skill in the art. It must be understood that the terms of the dictionary definitions are consistent with their meanings in the context of the related art, and the terms should not be ideally or excessively formally defined unless the context clearly dictates otherwise.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference symbols in the various drawings indicate like elements.

Fig. 1 is a configuration diagram of an external power supply system of a fuel cell 10 vehicle according to an exemplary embodiment of the invention. Referring to fig. 1, an external power supply system of a fuel cell 10 vehicle according to an exemplary embodiment of the present invention may include: a fuel cell 10; a high-voltage battery 30 connected to the fuel cell 10 via a main bus terminal; a charging/discharging unit 20 configured to charge or discharge the high-voltage battery 30; a power supply line that branches from the main bus terminal and is connected to a load 40 outside the vehicle to supply electric power of the fuel cell 10 or the high-voltage battery 30 to the load 40 outside the vehicle; and a controller 50 configured to operate the fuel cell 10 and the charge/discharge unit 20 based on the magnitude of power supplied to the load 40 outside the vehicle and the state of charge (SOC) of the high-voltage battery 30.

The fuel cell 10 may be a stack of fuel cells 10 that are supplied with hydrogen and oxygen, respectively, and may be configured to generate electrical energy by an electrochemical reaction of the hydrogen and oxygen therein. The fuel cell 10 may be connected to the high-voltage battery 30 via a main bus terminal. The primary bus terminal may be further connected to a motor and other accessory devices that drive the vehicle. The high voltage battery 30 may be configured to supply electric power to the main bus terminals while charging or discharging electric power generated by the fuel cell 10 via the main bus terminals. The charging/discharging unit 20 may be configured to adjust charging or discharging of the high voltage battery 30. The high voltage battery 30 may further include: a Battery Management System (BMS)60 configured to monitor a state of charge (SOC) of the fuel cell 10 and execute the charging/discharging unit 20 to adjust the state of charge (SOC).

The controller 50 may be included in a vehicle controller (e.g., a fuel cell controller (FCU)) of the fuel cell 10, or may be a separately formed controller. It is possible to operate the fuel cell 10 and the charge/discharge unit 20 based on the magnitude of power supplied to the load 40 outside the vehicle and the state of charge (SOC) of the high-voltage battery 30. The fuel cell 10 may normally be operated at the time of vehicle start of the fuel cell 10, but when the state of charge of the high-voltage battery 30 is sufficient and the required current of the fuel cell 10 is minimum, the operation of the fuel cell 10 may be stopped. The stopped state of the fuel cell 10 when the start of the vehicle is not terminated is referred to as an idle stop (e.g., FC idle stop) mode. The fuel cell 10 may be operated based on the corresponding mode to generate a current equal to or greater than a predetermined magnitude, thereby improving fuel economy.

In the idle stop mode of the fuel cell 10, hydrogen may be continuously supplied through the recirculation line, and the air supply line may be closed to stop the operation of the air compressor or blower, and the air control valve of the air supply line may adjust to close the air supplied to the fuel cell 10. The load 40 outside the vehicle is the load 40 that supplies electric power to the outside of the vehicle, and the load that is supplied with electric power from the fuel cell 10 or the high-voltage battery 30 when the fuel cell 10 vehicle is operated as a mobile generator. The corresponding load 40 may individually include a power converter such as an inverter. It is possible to determine whether the load 40 is connected to the power supply line branched from the main bus terminal by a separate sensor or the like.

Accordingly, it may be determined whether the power supply line is connected to the load 40 outside the vehicle, and in response to determining that the power supply line is connected to the load 40 outside the vehicle, the power supply line may be operated in the external power supply mode. The charge/discharge unit 20 may be a Direct Current (DC) converter disposed at a main bus terminal between the fuel cell 10 and the high-voltage battery 30. The DC converter 20 may be configured to change the voltage of the DC power through a DC/DC converter. The power supply line may be connected in parallel between the fuel cell 10 and the charging/discharging unit 20 so that the electric power from the fuel cell 10 or the high-voltage battery 30 can be supplied to the load 40 outside the vehicle. In other words, the power supply line may be connected to the main bus terminal between the fuel cell 10 and the charging/discharging unit 20 so as to be able to be supplied with electric power from the fuel cell 10 or electric power from the high-voltage battery 30 through the charging/discharging unit 20.

Fig. 2 is a flowchart of an external power supply method of a fuel cell 10 vehicle according to an exemplary embodiment of the present invention, and fig. 3 to 5 are diagrams showing the flowchart of fig. 2 in detail. The methods described herein below may be performed by a controller having a processor and a memory. Referring to fig. 2 to 5, an external power supply method of a fuel cell 10 vehicle according to an exemplary embodiment of the present invention may include: obtaining a magnitude of power to be supplied to a load 40 outside the vehicle (S100); determining a state of charge of the high voltage battery 30 (S200); and operating the fuel cell 10 and the DC converter 20 based on the obtained magnitude of power supplied to the load 40 outside the vehicle and the determined state of charge of the high-voltage battery 30 (S400, S500, and S600).

In the operations (S400, S500, and S600) of the fuel cell 10 and the DC converter 20, the control mode may be divided into a plurality of control modes based on the magnitude of power supplied to the load 40 outside the vehicle. In particular, the magnitude of the power supplied to the load 40 outside the vehicle may be a value obtained by summing the magnitude of other power consumed by the accessory device or the like and the magnitude of the power actually supplied to the load 40. In other words, in the mode of supplying electric power to the load 40 outside the vehicle, the value may be a value obtained by adding the magnitudes of all the power consumed by the loads 40 connected to the main bus terminals and outside the vehicle.

The control mode may be divided into three control modes (e.g., a low power mode, an intermediate power mode, and a high power mode) based on the magnitude of power supplied to the load 40 outside the vehicle, and may be divided into three or more or two control modes (S300). For example, the control mode may be divided into a low power mode, an intermediate power mode, and a high power mode based on A [ kW ] and B [ kW ], respectively (S310, S320).

In obtaining the magnitude of the power supplied to the load 40 outside the vehicle (S100), the magnitude of the power supplied to the load 40 outside the vehicle may be calculated by averaging the amount of power over a preset time (e.g., about 60 seconds). In particular, it may be assumed that the magnitude of the power supplied to the load 40 outside the vehicle does not suddenly change in real time as compared to the power consumption due to the operation of the vehicle. Therefore, the average value may be calculated every preset time (for example, about 10 seconds) while updating the amount of power supplied to the load 40, and thereby, the magnitude of power supplied to the load 40 outside the vehicle may be calculated. In determining the state of charge of the high-voltage battery 30 (S200), a ratio (%) of an amount of power that can be discharged from the high-voltage battery to a maximum chargeable amount of power according to the state of the high-voltage battery may be determined. The state of the high voltage battery may also be affected by an external environment such as temperature.

In general, control may be performed such that the proportion of the electric power supplied from the fuel cell 10 may increase as the magnitude of the power supplied to the load 40 outside the vehicle increases. In other words, the proportion of operating the fuel cell 10 may be increased toward the high power mode, thereby increasing the proportion of power supplied to the fuel cell 10. On the other hand, the operations of the fuel cell 10 and the DC converter 20 may be adjusted, and thus, as the magnitude of power supplied to the load 40 outside the vehicle decreases, the proportion of electric power supplied from the high-voltage battery 30 may increase. In other words, since the fuel cell 10 is operated toward the low power mode, the proportion of stopping the operation of the fuel cell 10 can be increased and the proportion of the electric power supplied from the high-voltage battery 30 by the charge or discharge of the high-voltage battery 30 can be increased.

A more specific method of controlling the external power supply in the plurality of modes is as follows. Referring to fig. 3, in the low power mode among the plurality of modes (S400), when the state of charge of the high voltage battery 30 is equal to or greater than a predetermined first SOC, the operation of the fuel cell 10 may be stopped and only the high voltage battery 30 is operated to supply electric power to the load 40 outside the vehicle (S420).

In other words, in the first SOC or more where it can be determined that the state of charge of the high-voltage battery 30 is sufficient, the operation of the fuel cell 10 may be stopped (S420) and only the high-voltage battery 30 may be configured to supply electric power to the load 40 outside the vehicle. In the first SOC, the high-voltage battery 30 may be set so as not to need to be charged any more (S410). In particular, it is possible to operate the charging/discharging unit 20 to supply electric power to the load 40 outside the vehicle using the high-voltage battery 30 while suppressing the boosting of the output voltage of the high-voltage battery 30 (S430). The output voltage of the fuel cell 10 may range from about 250 to 400V, and the output voltage of the high-voltage battery 30 may range from about 180 to 240V. The charging/discharging unit 20 may be configured to perform charging or discharging of the high-voltage battery 30, and may be configured to perform boosting between the fuel cell 10 and the high-voltage battery 30.

However, when the operation of the fuel cell 10 is stopped and the electric power is supplied to the load 40 only by the high-voltage battery 30, the charging/discharging unit 20 may be configured to suppress the boosting of the output voltage of the high-voltage battery 30, and thus, the high-voltage battery 30 may be discharged at a relatively low output voltage of the high-voltage battery 30. In other words, only the output voltage of the high-voltage battery 30 or the minimum boosted voltage (e.g., about 10[ V ]) may be increased and supplied to the load 40 (S430).

Since a separate inverter or the like is mounted on the load 40, it is possible to prevent a reduction in power conversion efficiency due to boosting, by allowing the charging/discharging unit 20 to minimize boosting, even if a relatively low voltage is supplied to the load 40. In addition, in the low power mode among the plurality of modes, if the state of charge of the high voltage battery 30 is less than the predetermined second SOC, it is possible to supply electric power to the load 40 outside the vehicle while charging the high voltage battery 30 using the fuel cell 10 (S450). The second SOC may be set to a value sufficient to charge the high-voltage battery 30 without discharging the high-voltage battery 30 (S440).

The high voltage battery 30 may be charged and the charging power of the charging/discharging unit 20 may be adjusted to the target power. Specifically, control may be performed to charge the high-voltage battery 30, thereby adjusting the charging power of the charging/discharging unit 20 to the target power. Additionally, the charging power of the charging/discharging unit may be adjusted to the target power using an error between the target power and the actual charging power of the charging/discharging unit 20 and a preset power gain. The power gain may be preset to a parameter calculated based on experiments using real vehicles.

Specifically, the target power is a target value of the charging power of the charger 20 and may be set equal to or larger than a preset minimum value. In the charging/discharging unit 20, when charging or discharging is performed in the minimum power range, the charging or discharging efficiency is the lowest. Therefore, when the charging/discharging unit 20 charges or discharges the high voltage battery 30, the charging/discharging unit 20 may be set equal to or greater than a preset minimum value (e.g., about 5kW), thereby preventing waste of electric power due to the charging or discharging. In other words, in the low power mode, the operation of the fuel cell 10 may be stopped to the maximum extent and the charge or discharge of the high voltage battery 30 may be maximized to supply electric power to the load 40 outside the vehicle.

Referring back to fig. 4, in the intermediate power mode among the plurality of modes (S500), when the state of charge of the high-voltage battery 30 is equal to or greater than the predetermined third SOC, the charging/discharging unit 20 may be operated to suppress charging or discharging of the high-voltage battery 30 (S520). The third SOC may be set such that the state of charge of the high-voltage battery 30 corresponds to an appropriate state (S510). Specifically, the charger 20 may be operated to suppress charging or discharging of the high voltage battery 30 (S520). As described above, when the charging/discharging unit 20 can be charged or discharged in the minimum power range, the charging or discharging efficiency is minimized and thus, when the charging or discharging is not required, the operation of the charging/discharging unit 20 may be stopped or the charging or discharging power may be adjusted to 0, thereby making it possible to minimize the power consumed by the charging/discharging unit 20.

In addition, in the intermediate power mode among the plurality of modes, when the state of charge of the high-voltage battery 30 is less than the predetermined third SOC, it is possible to supply electric power to the load 40 outside the vehicle while charging the high-voltage battery 30 using the fuel cell 10 (S570). Even when the charging unit 20 is operated to suppress charging or discharging of the high-voltage battery 30, a sensing offset or the like may be detected in a sensor configured to sense a voltage or power in the charging unit 20. In addition, the error may occur in real time in the load 40 outside the vehicle or in the power supply inside the vehicle. Therefore, even when operating to suppress charging or discharging, minimal charging or discharging may occur, and the state of charge of the high-voltage battery 30 may change.

When the predetermined fourth SOC has a state of charge of the high-voltage battery 30 greater than the third SOC, the controller 50 may be configured to stop operating the fuel cell 10 and allow only the high-voltage battery 30 to supply electric power to the load 40 outside the vehicle (S540). The fourth SOC corresponds to such an appropriate state: the state of charge of the high-voltage battery 30 is consumed by the discharge while the state of charge of the high-voltage battery 30 is sufficient and may be set to be the same as the first SOC (S530).

The operation of the fuel cell 10 may be stopped and the fuel cell 10 may be operated in a stop mode (FC idle). In particular, in the stop mode of the fuel cell 10, hydrogen supplied to the fuel cell 10 may be continuously recirculated, the supply of air supplied to the fuel cell 10 may be interrupted, and the driving of an air supply device such as a blower may be stopped. In particular, it is possible to operate the charging/discharging unit 20 to supply electric power to the load 40 outside the vehicle while suppressing the boosting of the output voltage of the high-voltage battery 30 (S550). The operation of discharging the high-voltage battery 30 may be continued until the state of charge of the high-voltage battery 30 becomes less than a predetermined third SOC (S560). In other words, in the intermediate power mode (S500), both the fuel cell 10 and the high-voltage battery 30 may be used to supply electric power to the load 40 outside the vehicle while the state of charge of the high-voltage battery 30 is maintained in a sufficient state.

Referring back to fig. 5, in the high power mode among the plurality of modes (S500), when the state of charge of the high-voltage battery 30 is less than the fifth SOC, the charging/discharging unit 20 may be operated to suppress charging or discharging of the high-voltage battery 30 (S690). The fifth SOC may be a state in which it is necessary to discharge the high-voltage battery 30 having a sufficient state of charge (S610). For example, the fifth SOC may be set equal to the first SOC or the fourth SOC. When the state of charge of the high-voltage battery 30 is less than the fifth SOC, it may be determined that the state of charge of the high-voltage battery 30 is at an appropriate level that can suppress charging or discharging of the high-voltage battery 30 and allow only the fuel cell 10 to supply electric power to the load 40 outside the vehicle (S690).

When the state of charge of the high-voltage battery 30 is equal to or greater than the fifth SOC, the charging unit 20 may be operated to supply electric power to the load 40 outside the vehicle through the high-voltage battery 30 (S640, S650), and when the magnitude of the power supplied to the load 40 outside the vehicle is less than a preset power value (S620), the operation of the fuel cell 10 may be stopped (S630). In other words, when the state of charge of the high-voltage battery 30 is equal to or greater than the fifth SOC, it may be determined that the high-voltage battery 30 needs to be discharged and, thus, the charging/discharging unit 20 may be operated to allow the high-voltage battery 30 to supply electric power to the load 40 outside the vehicle through the high-voltage battery 30 while discharging the high-voltage battery 30 (S630 and S640).

When the charge/discharge unit 20 charges or discharges the high-voltage battery 30, as described above, it may be charged or discharged at a preset minimum value (e.g., about 5 kW). Therefore, when discharging the high-voltage battery 30, the high-voltage battery 30 may be charged or discharged using a preset minimum value (e.g., about 5kW) or more.

Therefore, assuming that the magnitude of the power supplied from the high-voltage battery 30 to the load 40 outside the vehicle is a preset minimum value (for example, about 5kW), the magnitude of the power supplied from the fuel cell 10 and the high-voltage battery 30 to the load 40 outside the vehicle may be a preset power value (C [ kW ]) or more when the power generation efficiency of the fuel cell 10 is considered. The preset power value C kW may be preset so as not to be a portion in which the power generation efficiency of the fuel cell 10 and the efficiency of the charging and discharging unit 20 may be sharply decreased. In other words, since the power generation efficiency of the fuel cell 10 is the smallest in the portion in which the minimum power is generated, when very low power generation is required, the operation of the fuel cell 10 may be stopped and the fuel cell 10 may enter the FC stop mode (S630). Even in this case, the boosting of the charging unit 20 can be suppressed (S640).

When the state of charge of the high-voltage battery 30 is again reduced to an appropriate level (e.g., the third SOC) while the charging/discharging unit 20 is operated to allow the high-voltage battery 30 to supply electric power to the load 40 outside the vehicle (S660), the charging/discharging unit 20 may be configured to suppress charging or discharging of the high-voltage battery 30 again (S690). When the operation of the fuel cell 10 is stopped, the fuel cell 10 may be operated again and the electric power output from the fuel cell 10 can be supplied to the load 40 outside the vehicle. When the state of charge of the high voltage battery 30 is less than the sixth SOC, which may be less than the fifth SOC, the controller 50 may be configured to operate the fuel cell 10 to supply electric power to the load 40 outside the vehicle while charging the high voltage battery (S680). The sixth SOC may be sufficient to charge the high-voltage battery 30 at the minimum level of the state of charge of the high-voltage battery 30 and may be set to the same value as the second SOC (S670).

When the state of charge of the high-voltage battery 30 is charged to an appropriate level (e.g., a seventh SOC) that avoids the minimum level, the charging/discharging unit 20 may be operated to suppress the high-voltage battery 30 from being charged or discharged again. In other words, in the high power mode, by maximally utilizing the generated electric power of the fuel cell 10, it is possible to minimize the charge or discharge of the high voltage battery 30 and supply the electric power to the load 40 outside the vehicle.

Referring back to fig. 2, after the operations of the fuel cell 10 and the DC converter 20, the method of controlling the external power supply may further include determining a state of the fuel cell 10 (S700 and S800) and operating the fuel cell 10 based on the determined state of the fuel cell 10 (S900). In the steps S700 and S800 of determining the state of the fuel cell 10, it may be determined whether the fuel cell 10 is in the normal state, the dry-out state (S810), or the filling state (S820). The state of the fuel cell 10 may be determined using an I-V curve, measuring the impedance of the stack of fuel cells 10 using conventional techniques, or the like.

In response to the determination that the fuel cell 10 is in the normal state, the fuel cell 10 may be normally operated (S930). In response to determining that the fuel cell 10 is in the dry-out state (S810), the operation of the fuel cell 10 may be stopped and the DC converter 20 may be operated to suppress the boost of the output voltage of the high-voltage battery 30 (S910). In other words, in response to determining that the fuel cell 10 is in a dry-out state, it may be necessary to stop the supply of air to the fuel cell 10 to recover from dry-out. Therefore, when the state of charge of the high-voltage battery 30 is equal to or greater than the minimum level (e.g., the second SOC or the sixth SOC), the fuel cell 10 may be stopped, thereby recovering the dry-out state of the fuel cell 10.

At this time, since only the high-voltage battery 30 supplies electric power to the load 40 outside the vehicle, it is possible to operate the DC converter 20 so as to suppress the boosting of the output voltage of the high-voltage battery 30. In response to the determination that the fuel cell 10 is in the filling state (S820), it is possible to add a preset recovery control current to the required current of the fuel cell 10, thereby adjusting the supply of air to the fuel cell 10 (S920).

The supply of air to the fuel cell 10 may be performed by a blower, an air compressor, or the like. The air supply control of the fuel cell 10 may be performed by a Revolution Per Minute (RPM) adjustment of a fan or an air compressor, and the RPM of the fan or the air compressor may be based on a predetermined map according to a required current of the fuel cell 10. However, when the fuel cell 10 is in the filling state, more air than is required for the electric power generation of the required current needs to be supplied to the fuel cell 10, thereby solving the filling of the fuel cell 10. Therefore, it is possible to increase the supply of air to the fuel cell 10 by increasing the RPM of the blower or the air compressor by adding a predetermined recovery control current to the required current of the fuel cell 10.

The magnitude and period of the recovery control current may be preset as experimental values according to the plurality of patterns divided based on the magnitude of power supplied to the load 40 outside the vehicle or the required current of the fuel cell 10. In addition, the duration of adding a predetermined recovery control current to the required current of the fuel cell 10 may also be preset as an experimental value.

According to the external power supply system and the power supply method of a fuel cell vehicle of the present invention, it is possible to improve fuel economy by adjusting optimal power distribution according to the magnitude of power supplied to a load outside the vehicle. Further, even when electric power is supplied to a load outside the vehicle, the fuel cell can be operated while maintaining the fuel cell in an optimum state by determining the state of the fuel cell in real time.

While the invention has been shown and described with respect to specific exemplary embodiments, it will be apparent to those skilled in the art that various modifications and changes may be made to the invention without departing from the spirit and scope of the invention as defined in the following claims.