阅读说明：本技术 燃料电池系统 (Fuel cell system ) 是由 松尾润一 于 2021-05-12 设计创作，主要内容包括：本发明提供燃料电池系统,能够缩短直至获得车辆的允许行驶为止的时间。该燃料电池系统被搭载于在车辆启动时即便燃料电池不能发电也能够利用二次电池的电力进行行驶的车辆,其特征在于,具有上述燃料电池、上述二次电池以及控制部,在上述燃料电池的发电预处理时且存在来自上述燃料电池的利用上述二次电池的输出使上述车辆行驶的行驶请求时,上述控制部计算上述二次电池的放电允许能量,并根据该放电允许能量计算从上述车辆的行驶请求起至允许行驶为止所需的允许行驶延迟请求时间、且计量从上述车辆的行驶请求起的经过时间亦即允许行驶延迟时间,在上述允许行驶延迟请求时间的值小于上述允许行驶延迟时间的值时,上述控制部允许上述车辆的行驶。(The invention provides a fuel cell system capable of shortening the time until a vehicle is allowed to run. The fuel cell system is mounted on a vehicle capable of running with electric power of a secondary battery even if the fuel cell is unable to generate electric power at the time of starting the vehicle, characterized by comprising the fuel cell, the secondary battery, and a control unit, wherein the control unit calculates discharge allowable energy of the secondary battery when there is a travel request from the fuel cell to travel the vehicle by using an output of the secondary battery during power generation preprocessing of the fuel cell, and calculates a travel permission delay request time required from a travel request of the vehicle to a travel permission based on the discharge permission energy, and measures a travel permission delay time which is an elapsed time from the travel request of the vehicle, the control unit permits the vehicle to travel when the value of the travel permission delay request time is smaller than the value of the travel permission delay time.)

1. A fuel cell system mounted on a vehicle capable of running using electric power of a secondary battery even if a fuel cell cannot generate electric power when the vehicle is started,

comprising the fuel cell, the secondary battery, and a control unit,

the control unit calculates a discharge allowable energy of the secondary battery at the time of the power generation preprocessing of the fuel cell and when there is a travel request from the fuel cell to cause the vehicle to travel by using an output of the secondary battery, calculates a travel allowable delay request time required from the travel request of the vehicle to the travel allowable based on the discharge allowable energy, and measures a travel allowable delay time which is an elapsed time from the travel request of the vehicle,

the control portion permits the travel of the vehicle when the value of the travel permission delay request time is smaller than the value of the travel permission delay time.

2. The fuel cell system according to claim 1,

the control portion limits a vehicle request energy consumed by the vehicle during a fuel cell start request time required until the fuel cell can generate electricity, at the time of electricity generation preprocessing of the fuel cell and when the vehicle travels using the electric power of the secondary battery.

3. The fuel cell system according to claim 1 or 2,

the vehicle is started when the vehicle is started below freezing point.

4. The fuel cell system according to any one of claims 1 to 3,

further comprising a circulation pump for circulating and returning a fuel off-gas discharged from a fuel electrode of the fuel cell to the fuel cell,

the control unit stops the driving of the circulation pump when the electric power of the secondary battery is equal to or less than a predetermined 1 st threshold and the vehicle requested energy of the vehicle is equal to or more than a predetermined 2 nd threshold during the fuel cell activation request time while the vehicle is traveling using the electric power of the secondary battery.

Technical Field

The present disclosure relates to a fuel cell system.

Background

Fuel Cells (FC) are fuel cells (hereinafter, referred to simply as "cell stacks") formed by stacking a plurality of single cells (hereinafter, referred to simply as "cells") and pass as fuel gasBulk hydrogen (H)₂) With oxygen (O) as the oxidant gas₂) To extract electric energy. Hereinafter, the fuel gas and the oxidizing gas may be simply referred to as "reactant gas" or "gas" without being particularly distinguished from each other.

The unit cell of the fuel cell is generally composed of a Membrane Electrode Assembly (MEA) and 2 separators that sandwich both surfaces of the Membrane Electrode Assembly as needed.

The membrane electrode assembly has a proton (H) ion-containing layer⁺) A conductive solid polymer electrolyte membrane (hereinafter, also simply referred to as "electrolyte membrane") has a structure in which a catalyst layer and a gas diffusion layer are formed on each surface in this order. Therefore, the membrane electrode assembly may be referred to as a membrane electrode gas diffusion layer assembly (MEGA).

The separator generally has a structure in which a groove serving as a flow path for the reaction gas is formed on a surface in contact with the gas diffusion layer. The separator also functions as a collector of generated electric power.

In a fuel electrode (anode) of a fuel cell, hydrogen supplied from a gas flow path and a gas diffusion layer is protonated by a catalyst action of a catalyst layer and moves to an oxidant electrode (cathode) through an electrolyte membrane. The generated electrons work through an external circuit and move to the cathode. The oxygen supplied to the cathode reacts with the protons and the electrons at the cathode to generate water.

The generated water imparts an appropriate humidity to the electrolyte membrane, and excess water passes through the gas diffusion layer and is discharged to the outside of the system.

Various studies have been made on a fuel cell system mounted on a fuel cell vehicle (hereinafter, sometimes referred to as a vehicle).

For example, patent document 1 discloses a fuel cell vehicle in which a motor is driven by electric power of a battery when the SOC of the battery is equal to or greater than a predetermined value even if the fuel cell cannot generate electric power at the time of starting the fuel cell vehicle.

Patent document 2 discloses a method of controlling a fuel cell vehicle in which the vehicle is started to run by using only electric power charged in a secondary battery during the start of the fuel cell.

Patent document 3 discloses a fuel cell system in which the driving of the circulation pump is stopped when the temperature is low at the time of starting the fuel cell.

Patent document 4 discloses a fuel cell system that determines whether or not the battery can be started in a running mode based on a difference between a remaining battery SOC and an SOC required for FC startup.

Patent document 1: japanese laid-open patent publication No. 2001-266917

Patent document 2: japanese patent laid-open publication No. 2005-073475

Patent document 3: japanese patent laid-open publication No. 2007-220425

Patent document 4: japanese patent laid-open publication No. 2011-239639

If the predetermined value of the SOC of the secondary battery that allows the vehicle to travel by using only the electric power charged in the secondary battery during the start of the fuel cell is set to be constant, the electric power of the secondary battery cannot be effectively used flexibly, and there is a problem that it takes time until the vehicle is allowed to travel.

For example, even when the SOC slightly does not satisfy the predetermined value, there is electric power for running the vehicle using only the secondary battery. However, when the fuel cell system is controlled so that the permitted travel of the vehicle cannot be obtained until the power generation of the fuel cell can be achieved when the SOC of the secondary battery does not satisfy the predetermined value, there is a problem in that it takes time until the permitted travel of the vehicle is obtained.

Disclosure of Invention

The present disclosure has been made in view of the above circumstances, and a main object thereof is to provide a fuel cell system capable of shortening the time until a vehicle is allowed to travel.

The present disclosure provides a fuel cell system mounted on a vehicle capable of traveling using electric power of a secondary battery even if a fuel cell is unable to generate electric power when the vehicle is started, the fuel cell system including the fuel cell, the secondary battery, and a control unit,

the control unit calculates a discharge allowable energy of the secondary battery at the time of the power generation preprocessing of the fuel cell and when there is a travel request from the fuel cell to cause the vehicle to travel by an output of the secondary battery, calculates a travel allowable delay request time required from the travel request of the vehicle to the travel allowable based on the discharge allowable energy, and measures a travel allowable delay time which is an elapsed time from the travel request of the vehicle,

the control unit permits the vehicle to travel when the value of the travel permission delay request time is smaller than the value of the travel permission delay time.

In the present disclosure, the control unit may limit the vehicle request energy consumed by the vehicle during a fuel cell activation request time required until the fuel cell can generate power when the vehicle travels using the electric power of the secondary battery in the power generation preprocessing of the fuel cell.

In the present disclosure, the vehicle may be started at a below-freezing-point start of the vehicle.

In the present disclosure, the fuel cell system may further include a circulation pump for circulating and returning a fuel off-gas discharged from a fuel electrode of the fuel cell to the fuel cell,

the control unit may stop the driving of the circulation pump when the electric power of the secondary battery is equal to or less than a predetermined 1 st threshold and the vehicle request energy of the vehicle is equal to or more than a predetermined 2 nd threshold during the fuel cell activation request time while the vehicle is traveling using the electric power of the secondary battery.

According to the fuel cell system of the present disclosure, the time until the allowable travel of the vehicle is obtained can be shortened.

Drawings

Fig. 1 is a flowchart showing an example of a control method of the fuel cell system of the present disclosure.

Fig. 2 is a flowchart showing another example of the control method of the fuel cell system of the present disclosure.

Fig. 3 is a diagram showing an example of a relationship between time and electric power until the fuel cell starts generating electric power after the vehicle is allowed to run by the electric power of the secondary battery until the FC power generation preprocessing is completed (FC start completion).

Fig. 4 is a flowchart showing still another example of the control method of the fuel cell system of the present disclosure.

Fig. 5 is a schematic configuration diagram showing an example of the fuel cell system of the present disclosure.

Detailed Description

The present disclosure provides a fuel cell system mounted on a vehicle capable of traveling using electric power of a secondary battery even if a fuel cell is unable to generate electric power when the vehicle is started, the fuel cell system including the fuel cell, the secondary battery, and a control unit,

the control unit calculates a discharge allowable energy of the secondary battery at the time of the power generation preprocessing of the fuel cell and when there is a travel request of the vehicle from the fuel cell by using an output of the secondary battery, calculates a travel allowable delay request time required from the travel request of the vehicle to the travel allowable based on the discharge allowable energy, and measures a travel allowable delay time which is an elapsed time from the travel request of the vehicle,

the control unit permits the vehicle to travel when the value of the travel permission delay request time is smaller than the value of the travel permission delay time.

At the time of starting the fuel cell vehicle, there is a case where the starting time is delayed from the viewpoint of protecting the components, particularly at the time of starting at a temperature below freezing point. At this time, when the electric power of the secondary battery, the SOC of the secondary battery, the energy remaining amount of the secondary battery, and the like are sufficient, the vehicle can be caused to travel only by the secondary battery, and therefore the allowable travel (Ready ON determination) of the vehicle can be advanced. Conventionally, a determination of a vehicle's allowable travel is made based on whether or not the SOC of a secondary battery is equal to or greater than a predetermined threshold value. However, when the SOC is less than the predetermined threshold value, the allowable travel of the vehicle generally needs to be delayed until the fuel cell can generate power, and the marketability of the vehicle may be degraded.

When at least 1 cell of the fuel cell stack is partially clogged due to freezing, if the hydrogen concentration at the time of starting the fuel cell stack is low (the nitrogen concentration is high), hydrogen in the cell is used up, and a decrease in the voltage of the cell due to hydrogen shortage may occur, thereby damaging the fuel cell stack.

Therefore, the hydrogen concentration of each fuel electrode in the stack is increased in advance mainly below freezing point (replacement of the anode from nitrogen to hydrogen), and even if at least 1 cell freezes, it is possible to perform pre-power generation (warm-up), that is, to prevent the hydrogen in the cell from being completely deficient until the temperature in the fuel cell stack rises to exceed freezing point. This power generation preprocessing takes time, and thus the start of power generation of the fuel cell stack is delayed.

In the present disclosure, at the time of power generation preprocessing of the fuel cell, the travelable time of the vehicle using only the secondary cell is calculated from the SOC of the secondary cell, the state of degradation of the secondary cell, and the like, and the permitted travel delay request time required until the permitted travel of the vehicle is performed is calculated from the difference between the travelable time of the vehicle using only the secondary cell and the fuel cell activation request time required until power generation of the fuel cell can be achieved, so that the permitted travel delay time from the presence of the travel request of the vehicle due to insufficient SOC of the secondary cell until the permitted travel of the vehicle is performed can be minimized.

According to the present disclosure, by determining the timing of performing the travel permission of the vehicle in consideration of the discharge permission energy of the secondary battery calculated from the SOC of the secondary battery, the degradation state of the secondary battery, and the like, and the requested energy of the vehicle, it is possible to use the energy charged in the secondary battery when the discharge permission energy of the secondary battery is high, and it is possible to shorten the time until the travel permission of the vehicle is performed after the travel request of the vehicle is made.

The present disclosure can obtain a high effect not only at the time of normal start of the fuel cell but also at the time of sub-freezing start of the fuel cell.

The fuel cell system of the present disclosure has at least a fuel cell, a secondary cell, and a control portion.

The fuel cell system of the present disclosure can be mounted on a vehicle that can run using electric power of a secondary battery even if the fuel cell cannot generate electric power at the time of starting the vehicle.

The fuel cell system of the present disclosure is generally mounted on a fuel cell vehicle whose driving source is an electric motor (motor) and used.

The motor is not particularly limited, and may be a conventionally known drive motor.

The fuel cell may be a fuel cell stack that is a stack of a plurality of fuel cells stacked together.

The number of stacked single cells is not particularly limited, and may be, for example, 2 to several hundred, or 2 to 200.

The fuel cell stack may include end plates at both ends in the stacking direction of the unit cells.

A single cell of the fuel cell includes a membrane electrode assembly including at least an oxidant electrode, an electrolyte membrane, and a fuel electrode, and may include 2 separators sandwiching both surfaces of the membrane electrode assembly as necessary.

The membrane may have reactant gas flow paths on the face in contact with the gas diffusion layer. The separator may have a refrigerant flow path for keeping the temperature of the fuel cell constant on the surface opposite to the surface in contact with the gas diffusion layer.

The separator may have a supply hole and a discharge hole for allowing the reactant gas and the refrigerant to flow in the stacking direction of the unit cells.

Examples of the supply holes include a fuel gas supply hole, an oxidizing gas supply hole, and a refrigerant supply hole.

Examples of the discharge holes include a fuel gas discharge hole, an oxidant gas discharge hole, and a refrigerant discharge hole.

The separator may be an air-impermeable conductive member or the like. Examples of the conductive member include dense carbon that is formed by compressing carbon so as to be impermeable to air, and a metal (for example, iron, aluminum, stainless steel) plate that has been press-formed. In addition, the separator may have a current collecting function.

The fuel cell stack may include manifolds such as an inlet manifold communicating with the supply holes and an outlet manifold communicating with the discharge holes.

Examples of the inlet manifold include an anode inlet manifold, a cathode inlet manifold, and a refrigerant inlet manifold.

Examples of the outlet manifold include an anode outlet manifold, a cathode outlet manifold, and a refrigerant outlet manifold.

The oxidizer electrode includes an oxidizer electrode catalyst layer and a gas diffusion layer.

The fuel electrode includes a fuel electrode catalyst layer and a gas diffusion layer.

The oxidant electrode catalyst layer and the fuel electrode catalyst layer may include, for example, a catalytic metal for promoting an electrochemical reaction, an electrolyte having proton conductivity, carbon particles having electron conductivity, and the like.

As the catalyst metal, for example, platinum (Pt), an alloy of Pt and another metal (for example, a Pt alloy in which cobalt, nickel, or the like is mixed), or the like can be used.

The electrolyte may be a fluorine resin or the like. As the fluorine-based resin, for example, Nafion solution or the like can be used.

The catalytic metal is supported on carbon particles, and in each catalyst layer, the carbon particles (catalyst particles) supporting the catalytic metal and an electrolyte may be present in a mixed state.

For the carbon particles for supporting the catalytic metal (carbon particles for supporting), for example, water-repellent carbon particles or the like in which water repellency of the carbon particles per se is improved by heat treatment of commercially available carbon particles (carbon powder) can be generally used.

The gas diffusion layer may be a conductive member having gas permeability, or the like.

Examples of the conductive member include a carbon porous body such as carbon cloth and carbon paper, and a metal porous body such as metal mesh and foamed metal.

The electrolyte membrane may be a solid polymer electrolyte membrane. Examples of the solid polymer electrolyte membrane include fluorine electrolyte membranes such as perfluorosulfonic acid membranes containing water and hydrocarbon electrolyte membranes. The electrolyte membrane may be, for example, a Nafion membrane (manufactured by dupont).

The fuel cell system may have a reaction gas supply portion that supplies a reaction gas to an electrode of the fuel cell.

The reaction gas supply unit supplies a reaction gas to the fuel cell stack.

The reaction gas is a concept including a fuel gas and an oxidant gas.

The reactant gas supply unit may be a fuel gas supply unit, an oxidant gas supply unit, or the like, and the fuel cell system may include either one of these supply units or both of these supply units.

The fuel cell system may have a fuel gas supply portion that supplies fuel gas to a fuel electrode of the fuel cell.

The fuel gas is a gas mainly containing hydrogen, and may be, for example, hydrogen gas.

Examples of the fuel gas supply unit include a fuel tank and the like, and specifically include a liquid hydrogen tank, a compressed hydrogen tank and the like.

The fuel cell system may include a fuel gas supply passage.

The fuel gas supply flow path connects the fuel cell and the fuel gas supply unit, and can supply the fuel gas from the fuel gas supply unit to the fuel electrode of the fuel cell.

The fuel cell system may be provided with a circulation flow path.

The circulation flow path can recover the fuel off gas discharged from the fuel electrode of the fuel cell and return the fuel off gas to the fuel electrode of the fuel cell as a circulation gas.

The fuel off gas includes fuel gas that passes through the fuel electrode in an unreacted state, moisture that reaches the fuel electrode from water generated in the oxidizer electrode, and oxidizer gas that can be supplied to the fuel electrode during scavenging.

The fuel cell system may include a circulation pump such as a hydrogen pump for adjusting the flow rate of the circulation gas, an ejector (ejector), and the like in the circulation path as necessary.

The circulation pump may be electrically connected to the control unit, and the control unit may control on/off, the rotation speed, and the like of the drive of the circulation pump to adjust the flow rate of the circulation gas.

The ejector is disposed, for example, at a junction of the fuel gas supply flow path and the circulation flow path, and supplies a mixed gas including the fuel gas and the circulation gas to a fuel electrode of the fuel cell. As the ejector, a conventionally known ejector can be used.

A gas-liquid separator for reducing moisture in the fuel offgas may be provided in the circulation flow path. Further, a drain passage branched from the circulation passage by the gas-liquid separator and a drain valve provided in the drain passage may be provided.

In the gas-liquid separator, the moisture separated from the fuel offgas may be discharged by opening a drain valve provided in a drain flow path branched from the circulation flow path.

The drain valve is electrically connected to the control unit, and the amount of liquid water discharged can be adjusted by controlling the opening and closing of the drain valve by the control unit.

The fuel cell system may include a fuel off-gas discharge unit.

The fuel off-gas discharge portion can discharge the fuel off-gas to the outside (outside the system). The outside may be the outside of the fuel cell system or the outside of the vehicle.

The fuel off-gas discharge unit may include a fuel off-gas discharge valve, and may further include a fuel off-gas discharge flow path as necessary.

The fuel off-gas discharge valve is electrically connected to the control unit, and the control unit controls the opening and closing of the fuel off-gas discharge valve to adjust the discharge flow rate of the fuel off-gas.

The fuel off-gas discharge flow path may be branched from the circulation flow path, for example, and may discharge the fuel off-gas to the outside when the hydrogen concentration in the fuel off-gas is too low.

The fuel cell system may include an oxidizing gas supply unit, an oxidizing gas supply passage, and an oxidizing gas discharge passage.

The oxidizing gas supply unit supplies an oxidizing gas to at least an oxidizing electrode of the fuel cell.

As the oxidizing gas supply unit, for example, an air compressor or the like can be used. The air compressor is driven in accordance with a control signal from the control unit, and introduces the oxidizing gas to the cathode side (the oxidizing electrode, the cathode inlet manifold, and the like) of the fuel cell.

The oxidizing gas supply passage connects the oxidizing gas supply unit to the fuel cell, and allows the oxidizing gas to be supplied from the oxidizing gas supply unit to the oxidizing electrode of the fuel cell.

The oxidant gas is an oxygen-containing gas, and may be air, dry air, pure oxygen, or the like.

The oxidizing gas discharge flow path enables the oxidizing gas to be discharged from the oxidizing electrode of the fuel cell.

The oxidizing gas discharge channel may be provided with an oxidizing gas pressure regulating valve.

The oxidizing gas pressure regulating valve is electrically connected to the controller, and the controller opens the oxidizing gas pressure regulating valve to discharge the reacted cathode off-gas from the oxidizing gas discharge passage. Further, the opening degree of the oxidizing gas pressure regulating valve is adjusted, whereby the oxidizing gas pressure (cathode pressure) supplied to the oxidizing electrode can be adjusted.

An intercooler may be disposed in the oxidizing gas supply passage. The intercooler is connected to the refrigerant circulation flow path, exchanges heat with the refrigerant, and cools the oxidizing gas discharged from the oxidizing gas supply unit. When there is a request for warm-up (power generation preprocessing) of the fuel cell, the refrigerant is heated by the heat of the oxidant gas compressed by the oxidant gas supply unit and having a high temperature.

The fuel cell system may include a bypass passage that branches from the oxidizing gas supply passage on the downstream side of the intercooler and is connected to the oxidizing gas discharge passage while bypassing the fuel cell. A bypass valve that controls the open state of the bypass flow path is disposed in the bypass flow path. The bypass valve is electrically connected to the control unit, and is opened by the control unit when the oxidizing gas supply unit is driven to consume the electric power of the secondary battery in a situation where, for example, the charge capacity of the secondary battery is not large enough during regenerative power generation of the drive motor. This prevents the oxidizing gas from being sent to the fuel cell and discharged to the oxidizing gas discharge passage.

The fuel gas supply channel and the oxidizing gas supply channel may be connected to each other via a joining channel. A scavenging valve may be provided in the merged channel.

The scavenging valve is electrically connected to the control unit, and the scavenging valve is opened by the control unit, whereby the oxidizing gas in the oxidizing gas supply unit can be introduced into the fuel gas supply passage as the scavenging gas.

The scavenging gas used for scavenging may be a reaction gas, which may be a fuel gas, an oxidant gas, or a mixed reaction gas containing both gases.

The fuel cell system may include a coolant supply unit and a coolant circulation flow path as a cooling system for the fuel cell.

The refrigerant circulation flow path communicates with a refrigerant supply hole and a refrigerant discharge hole provided in the fuel cell, and allows the refrigerant supplied from the refrigerant supply unit to circulate inside and outside the fuel cell, thereby cooling the fuel cell.

The coolant supply unit may be, for example, a cooling water pump.

The refrigerant circulation flow path may be provided with a radiator that radiates heat of the cooling water.

As the cooling water (refrigerant), for example, a mixed solution of ethylene glycol and water can be used to prevent freezing at low temperatures.

The fuel cell system may be provided with a secondary battery.

The secondary battery (battery) may be any battery as long as it can be charged and discharged, and examples thereof include conventionally known secondary batteries such as a nickel metal hydride secondary battery and a lithium ion secondary battery. The secondary battery may include an electric storage element such as an electric double layer capacitor. The secondary battery may have a structure in which a plurality of secondary batteries are connected in series. The secondary battery supplies electric power to an electric motor such as a motor, an oxidant gas supply unit such as an air compressor, and the like. The secondary battery may be configured to be chargeable from a power supply external to the vehicle, for example, a household power supply. The secondary battery may be charged by the output of the fuel cell.

The fuel cell system may include an auxiliary device using a battery as a power source.

Examples of the auxiliary device include a lighting device of a vehicle.

In addition, the fuel cell system of the present disclosure may be provided with a state of charge sensor that detects the remaining capacity of the secondary battery. The state-of-charge sensor detects a state-of-charge value (SOC) of the secondary battery. The charge state sensor may be connected to the control section. The control unit may be configured to be able to detect a charge state value of the secondary battery based on an output of the charge state sensor.

The control unit may control management of the charge state value of the secondary battery and charging and discharging of the secondary battery.

The State of Charge value (SOC) represents the ratio of the Charge capacity of the secondary battery to the full Charge capacity, which is SOC 100%.

The control unit controls the gas flow rate of the reaction gas.

The control unit may be connected to a gas-liquid separator, a drain valve, a fuel off-gas discharge valve, an oxidizing gas pressure regulating valve, a scavenging valve, a fuel gas supply unit, an oxidizing gas supply unit, a bypass valve, a secondary battery, a circulation pump, and the like via an input/output interface. The control unit may be electrically connected to an ignition switch that can be mounted on the vehicle.

The control unit is a component physically including an arithmetic processing device such as a CPU (central processing unit), a storage device such as a ROM (read only memory) storing a control program and control data processed by the CPU, a RAM (random access memory) mainly used as various work areas for control processing, and an input/output interface. The control unit may be a control device such as an ECU (engine control unit).

1. Embodiment 1

According to embodiment 1 of the present disclosure, a decrease in the traveling performance of the vehicle is avoided by calculating the discharge allowable energy of the secondary battery based on the SOC, the state of degradation, and the like of the secondary battery, and extending the allowable traveling delay time.

Fig. 1 is a flowchart showing an example of a control method of the fuel cell system of the present disclosure. Further, the present disclosure is not necessarily limited to only the present exemplary embodiment.

The control unit calculates a discharge allowable energy of the secondary battery at the time of power generation preprocessing of the fuel cell and when there is a travel request from the fuel cell to travel the vehicle by using an output of the secondary battery, calculates an allowable travel delay request time required from the travel request of the vehicle to the permission of the travel based on the discharge allowable energy, measures an allowable travel delay time which is an elapsed time from the travel request of the vehicle, and permits the travel of the vehicle when a value of the allowable travel delay request time is smaller than a value of the allowable travel delay time.

For example, the control unit may check the temperature at the time of starting the fuel cell, the presence or absence of freezing of a component in the fuel cell system, the presence or absence of a failure of the component, and the like, and may make a travel request for traveling the vehicle by the output of the secondary battery from the fuel cell when the control unit determines that the output of the fuel cell can be made at least a certain level within a predetermined time. This is because if the output of the fuel cell cannot be ensured after the vehicle using the secondary battery travels, the traveling performance of the vehicle may be degraded. Therefore, when the output of the fuel cell is not equal to or more than a certain level within a predetermined time, the traveling request for traveling the vehicle by the output of the secondary battery from the fuel cell is not made.

As for the temperature of the fuel cell, for example, a temperature sensor may be provided in the fuel cell system and the temperature of the fuel cell may be measured using the temperature sensor. The temperature sensor is electrically connected to the control unit, and the control unit can detect the temperature output from the temperature sensor. The temperature of the fuel cell may be the temperature of the cooling water.

The presence or absence of the freezing of the component may be determined, for example, by providing a temperature sensor in the fuel cell system, measuring the temperature of the component using the temperature sensor, and determining that the component is frozen when the temperature is below the freezing point.

The presence or absence of a failure of a component may be determined by, for example, measuring the resistance of the component by providing a resistance sensor in the fuel cell system, and determining that the component has failed when the resistance is equal to or greater than a predetermined value.

The control unit calculates a discharge allowable energy of the secondary battery.

The discharge allowable energy (dischargeable energy) of the secondary battery may be appropriately set in consideration of the requested energy of the vehicle and the like according to the SOC of the secondary battery, the state of degradation of the secondary battery, and the like.

In addition to the above, the discharge allowable energy of the secondary battery may be set in consideration of the lower limit value of the SOC of the secondary battery, such that the secondary battery does not over-discharge.

The discharge allowable energy (kJ) of the secondary battery can be calculated, for example, by the following formula (a).

Formula (A): the discharge allowable energy of the secondary battery (secondary battery SOC at the time of vehicle start-target SOC of the secondary battery at the time of completion of vehicle travel using the secondary battery) ÷ 100 × theoretical full charge energy (kJ) of the secondary battery × degradation coefficient of the secondary battery

The target SOC of the secondary battery at the time of completion of the vehicle running by the secondary battery is the SOC of the secondary battery at the time of completion of the power generation preliminary processing by the fuel cell when the vehicle is run by only the electric power of the secondary battery from the start of the power generation preliminary processing by the fuel cell.

For example, the degradation coefficient of the secondary battery can be calculated from the ratio of the actual measured full charge energy of the secondary battery at present to the theoretical full charge energy of the secondary battery, taking into account the total number of charge and discharge times of the secondary battery, and the like.

The control unit calculates a travel permission delay request time required from a travel request of the vehicle to a travel permission based on the discharge permission energy of the secondary battery.

The allowable travel delay request time (Ready delay time) can be calculated, for example, by the following equation (B).

Formula (B): request time for travel permission (sec) × (vehicle travel request time using secondary battery (sec) × vehicle travel power using secondary battery (kW) — discharge permission energy of secondary battery (kJ))/(vehicle travel power using secondary battery (kW))

Here, the power (kW) used for traveling of the vehicle using the secondary battery can be estimated, for example, in consideration of the power consumption of the drive motor used for traveling of the vehicle, the power consumption of an air conditioner (air conditioner or the like), the power consumption of an auxiliary machine, and the like.

The control unit measures an allowable travel delay time, which is an elapsed time from a travel request of the vehicle.

The allowable travel delay time may be determined by, for example, providing a time meter in the fuel cell system and measuring an elapsed time from a travel request of the vehicle using the time meter. The time counter may be electrically connected to the control unit, and the control unit may detect the travel delay time allowed to be output from the time counter.

The control unit permits the vehicle to travel when the value of the travel delay allowed request time is smaller than the value of the travel delay allowed time. When the value of the allowable travel delay request time is, for example, 10 seconds, the travel of the vehicle is allowed when the value of the allowable travel delay time exceeds 10 seconds. In other words, the control unit does not permit the vehicle to travel until the travel permission delay time elapses 10 seconds. That is, when the value of the travel permission delay request time is 10 seconds, the control unit forcibly prohibits the travel of the vehicle within 10 seconds and causes the vehicle to stand by. Thus, while the vehicle is running using only the electric power of the secondary battery in the power generation preprocessing of the fuel cell, it is possible to suppress the vehicle from stopping due to the shortage of the electric power of the secondary battery.

2. Embodiment 2

Since it takes a predetermined time until the fuel cell can generate electric power (until the fuel cell is started), when the dischargeable power of the secondary battery is large, the energy consumption of the secondary battery increases until the power generation of the fuel cell is started, and the output of the secondary battery decreases due to the SOC depletion of the secondary battery, so that there is a possibility that the electric power finally used for running the vehicle by the secondary battery is insufficient.

On the other hand, in order not to suppress the output of the secondary battery until the power generation of the fuel cell is started and not to cause a shortage of electric power for the travel of the vehicle, it is necessary to delay the time from the presence of the travel request of the vehicle until the permission of the travel, and the commercial value of the vehicle is lowered. Further, as the dischargeable power of the secondary battery is higher, the set value of the SOC of the secondary battery required for the allowable travel needs to be higher, and thus the commercial value of the vehicle is further reduced. This is because, since power (kW) × time (sec) ═ energy (kJ), when the same time power (time power) is consumed in the case where power is large as in the case where power is small, the energy consumption in the case where power is large.

According to the present disclosure, the output of the secondary battery is suppressed until the power generation of the fuel cell is started, thereby suppressing the energy consumption of the secondary battery, and the output of the secondary battery is continuously secured for a certain period of time until the power generation of the fuel cell is started.

Fig. 2 is a flowchart showing another example of the control method of the fuel cell system of the present disclosure.

The control unit limits the vehicle request energy consumed by the vehicle during a fuel cell start request time required until the fuel cell can generate power, during power generation preprocessing of the fuel cell and when the vehicle is traveling using electric power of the secondary battery.

On the other hand, after the fuel cell start request time has elapsed, the control unit ends the control without limiting the vehicle request energy.

Fig. 3 is a diagram showing an example of a relationship between time and electric power between when the vehicle is allowed to run by the electric power of the secondary battery and after the power generation preprocessing of the fuel cell is completed (FC start is completed) and the fuel cell starts generating electric power.

As shown in fig. 3, until FC start is completed, vehicle driving power, air conditioning power, and the like may be limited, thereby limiting vehicle request energy such as vehicle running energy, air conditioning consumption energy, and the like.

An upper limit of energy requested from the vehicle (vehicle requested energy) is set at the time of power generation preprocessing of the fuel cell and when the vehicle travels using electric power of the secondary cell, and a travel time of the vehicle using only electric power of the secondary cell until power generation preprocessing of the fuel cell is completed (power generation of the fuel cell is started) is secured.

Since the fuel cell activation request time required until the fuel cell can generate power differs depending on the temperature of the fuel cell, the size of the fuel cell, the number of unit cells included in the stack, and the like, the fuel cell activation request time may be measured in advance by an experiment or the like, and the control unit may store the fuel cell activation request time.

The vehicle request energy includes energy consumption of a drive motor for running the vehicle, energy consumption of an air conditioner, energy consumption of auxiliary equipment, and the like.

In the limit of the vehicle requested energy, from the viewpoint of suppressing the vehicle from being stopped due to the SOC of the secondary battery running out before the fuel cell can generate electricity, for example, the upper limit value of the vehicle requested energy may be set so that the energy consumed by the secondary battery before the fuel cell can generate electricity is equal to or less than the discharge allowable energy of the secondary battery. Specifically, the energy consumption of the secondary battery during the traveling of the vehicle may be reduced by, for example, reducing the upper limit of the traveling speed of the vehicle or limiting the upper and lower limits of the set temperature of the air conditioner.

3. Embodiment 3

If the output of the secondary battery decreases to a certain value or less due to some factor during the power generation preprocessing of the fuel cell and during the running of the vehicle using the electric power of the secondary battery, the power generation preprocessing is continued with the fuel cell being maintained, and if the fuel cell cannot generate electric power, the running performance of the vehicle decreases, and the vehicle may not run.

According to the present disclosure, when the output of the secondary battery decreases to or below the predetermined 1 st threshold value and the vehicle request energy are also or above the predetermined 2 nd threshold value due to some factor during the power generation preprocessing of the fuel cell and during the vehicle running using the electric power of the secondary battery, the driving of the circulation pump is stopped, and the power generation preprocessing of the fuel cell (for example, the replacement processing from nitrogen gas to hydrogen) is terminated halfway to advance the power generation of the fuel cell. In this case, in order to suppress the fuel cell from becoming a power generation failure (negative voltage), the driving of the circulation pump is stopped and the power generation of the fuel cell is started to ensure a desired output of the fuel cell, thereby ensuring the startability of the fuel cell.

When the replacement process (anode fuel gas concentration increasing process) of the fuel electrode with the fuel gas such as hydrogen from the inert gas such as nitrogen is not performed or it takes more time than a predetermined time until the replacement process is completed due to some factor, the circulation pump non-circulation operation in which the driving of the circulation pump is stopped to generate the electric power of the fuel cell can be performed for the purpose of improving the startability of the fuel cell, particularly the startability at the sub-freezing point.

Specifically, the circulation pump non-circulation operation means that the fuel off-gas discharged from the fuel electrode of the fuel cell is discharged to the outside of the system without circulating it, and the fuel cell is caused to generate electricity only by the fuel gas from the fuel gas supply unit. Therefore, a fuel cell system for performing a circulation-pump-non-circulation operation actually includes a fuel gas supply unit and a fuel off-gas discharge unit.

Since the nitrogen concentration is less likely to increase in at least 1 cell by the non-circulating operation of the circulation pump of the fuel cell, even if ice is formed in the cell, a required amount of fuel gas can be continuously supplied into the cell. However, the fuel gas flow rate at the fuel electrode is reduced as a result of the collision caused by the circulation pump not rotating. Therefore, it is difficult to supply the fuel gas to the narrow holes in at least 1 unit cell and the unit cells located far from the anode inlet manifold of the stack, and a local fuel gas deficiency portion is generated in the fuel cell, and the fuel cell may be deteriorated.

Fig. 4 is a flowchart showing still another example of the control method of the fuel cell system of the present disclosure.

The fuel cell system of the present disclosure further includes a circulation pump that circulates the fuel off-gas discharged from the fuel electrode of the fuel cell and returns the fuel off-gas to the fuel cell, and the control unit stops the driving of the circulation pump when the electric power of the secondary cell is equal to or less than a predetermined 1 st threshold and the vehicle request energy of the vehicle is equal to or more than a predetermined 2 nd threshold during the fuel cell start request time while the vehicle is traveling using the electric power of the secondary cell.

On the other hand, when the electric power of the secondary battery is smaller than the predetermined 1 st threshold or the vehicle request energy is smaller than the predetermined 2 nd threshold after the fuel cell activation request time has elapsed, the control unit ends the control without stopping the driving of the circulation pump.

The 1 st threshold value is not particularly limited as long as it is the electric power (output) of the secondary battery that does not make the vehicle unable to travel, and may be, for example, the electric power of the secondary battery immediately before the vehicle is hindered from traveling, and may be appropriately set according to the traveling performance of the vehicle or the like.

The 2 nd threshold value may be, for example, the allowable travel energy of the secondary battery or less so that the vehicle does not become unable to travel, and may be appropriately set according to the traveling performance of the vehicle or the like.

Fig. 5 is a schematic configuration diagram showing an example of the fuel cell system of the present disclosure. Further, the fuel cell system of the present disclosure is not limited to the present exemplary example.

The fuel cell system 100 shown in fig. 5 includes a fuel cell 11, a circulation flow path 12, a gas-liquid separator 20, a water discharge flow path 21, a water discharge valve 22, a fuel gas supply unit 30, a fuel gas supply flow path 31, an oxidizing gas supply unit 40, an oxidizing gas supply flow path 41, an oxidizing gas discharge flow path 42, a control unit 50, a merging flow path 51, a scavenging valve 52, and a circulation pump 60, and includes a secondary cell, although not shown.

The gas-liquid separator 20, the drain valve 22, the fuel gas supply unit 30, the oxidizing gas supply unit 40, the purge valve 52, the circulation pump 60, and the not-shown secondary battery are electrically connected to the control unit 50, and are controlled by the control unit 50.

Description of reference numerals:

11 … fuel cell; 12 … circulation flow path; 20 … gas-liquid separator; 21 … drainage path; 22 … drain valve; 30 … fuel gas supply section; 31 … fuel gas supply flow path; 40 … oxidant gas supply unit; 41 … oxidant gas supply flow path; 42 … oxidant gas exhaust flow path; 50 … control section; 51 … flow into the flow path; 52 … purge valve; 60 … circulation pump; 100 … fuel cell system.