KR101575336B1 - Air and coolant circuit configurations and control of fuel cell systems as power source in automotive stationary and portable applications - Google Patents

Abstract

The heat is generated, the heat is generated, the cooling water is introduced, the introduced cooling water is guided to the cooling water outlet, and the generated heat is transferred to the introduced cooling water, whereby the heat generated as the cooling water is guided out of the heat source A heat source adapted to be removed from the heat source; An air supply source adapted to supply air to the heat source; An air supply control device adapted to regulate air supply from an air source to a heat source based on dynamic feedback temperature characteristics from a heat source; A cooling water supply source adapted to supply cooling water to the heat source; And a cooling water control device adapted to regulate the cooling water flow rate based on the estimated feed-forward heat source characteristics and adapted to regulate the cooling water temperature based on the dynamic feedback temperature characteristic.

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a fuel cell system, a fuel cell system, a fuel cell system, and a fuel cell system.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell device field, and more particularly, to an apparatus and method for controlling air and cooling water characteristics of a fuel cell device. The present invention is particularly suitable for the vehicle field, but is also suitable for other fields as well. Furthermore, the present invention is particularly suitable for fuel cell devices, but is also suitable for other power sources that generate heat as well.

PEM (Polymer Electrolyte Membrane) Air flow and temperature control of the fuel cell stack is a critical issue for the performance and durability of the stack. Insufficient supply of oxygen at sudden current changes can cause oxygen deficiency in the catalyst and can not produce the necessary power sufficiently. Inadequate blocking of the generated heat causes an overheating point between the layers or thermally stresses the layers, which shortens the lifetime of the stack. Therefore, the reactants and temperature in the cell must be managed by maintaining the performance of the stack as well as maintaining the best possible performance.

The temperature changes continuously as the load current changes. Temperature directly affects thermal stresses of objects as well as chemical reactions and moisture transfer. Improving the performance and durability of power units is an important issue. Conversely, elevated temperatures can facilitate the removal of water produced in the catalyst and increase the mobility of water vapor within the membrane, which alleviates overvoltage. In addition, reducing the power consumption required to operate the electric cooling water pump makes it possible to ensure the efficiency of the power plant. Therefore, the development of temperature control strategies is a major concern to address concerns that need to improve performance with reliable operation.

Throughout this specification, the following names (alphabets, superscripts, subscripts, Greek symbols, etc.) are used.

Area A m ²

C Mass Concentration kg · m ^-3

Cp Specific heat W · m ^-2 · ° C ^-1

F Faraday constant

Fr Radiator Overall area m ²

i Current density A · m ^-2

J Rotational inertia kg · m ²

m mass kg

M mol mass kg · mol ^-1

N molar flux mol · s ^-1 · m ^-3

n number

p (partial) Pressure Pa

Q heat transfer J

R gas constant

R resistance Ω

s entropy J · mol ^-1 · K ^-1

t thickness m

T temperature K

w mass flux kg

around amb

an anode

bl blower

c cooling water

ca cathode

catl catalyst layer

cond conduction

conv convection

cv Inspection volume

diffusion diff

elec electric

g gas

i motor

membrane membrane layer

pl associative flow

rad radiator

res store

s stator

sou sauce

st stack

ε porosity

τ torsion, torque

λ moisture content, ratio

ρ density kg · m ^-3

ω angular velocity rad · s ^-1

η Efficiency

Bundle joint V · s · rad ^-1

PEM fuel cells are chemical devices that generate electrical power and release heat and water (for example, oxygen and hydrogen) as a by-product of chemical reactions. Thus, fuel cells are considered to be independent of air pollution, which makes PEM fuel cells a potential and alternative power source for future vehicle and stationary equipment.

In order to replace conventional power sources, fuel cell devices must be analyzed and evaluated for performance, efficiency, and reliability. The properties of PEM fuel cells are correlated with factors including the transport of reactants and byproducts, the treatment of heat generated by an electric current through an electrochemical reaction or through the cell, and the control of humidity to maintain proper electrolyte conductivity .

Fuel cell peripherals (BOPs) are a group of device components that supply reactants, remove generated heat, manage the generated water, and control the actuator. Typical components needed to operate a PEM fuel cell device, such as the conventional PEM fuel cell device 100 shown in Figure 1, are a hydrogen tank 110 for storing fuel and an air compressor or blower 120, Respectively, have corresponding inlet / outlet manifolds 115, 125, 185, 195, respectively. The hydrogen tank 110 and the blower 120 are connected to the PEM fuel cell 140 so that a fluid flows. The apparatus 100 also includes a humidifier 130 that supplies moist oxygen, a bypass valve 150, a radiator 160 with a fan, a fluid reservoir 170, a coolant pump 180, Several control valves 113, 123, 187, and 197 for proper processing, and controllers.

In order to control the fuel cell power system, it is necessary to understand the dynamic behavior of the stacks interacting with other BOP components. Because of the complexity of the device, a dynamic model is used to efficiently design and efficiently evaluate the controllers. Models for PEM fuel cell stacks, air feeders, and thermal devices are briefly described below.

Most fuel cell models describe the physical behavior of a PEM fuel cell, which is based on empirical equations that fit the curve of a particular stiffness characteristic, or computational fluid dynamics (CFD) to solve mass and charge transfer. The former was proposed in the design of the controller for the air supply. The dynamics required in the cell were improved by reflecting the charging and discharging behavior of the bilayer at the interface between the electrode and the electrolyte. However, the model does not completely contain the gas and temperature dynamics that occur in the flow path and in the current-carrying cell. In addition, we did not consider the partial pressure drop along the pores of the Gas Diffusion Layer (GDL), which affects the net pressure affecting the chemical reaction rate and increases the overvoltage. The temperature rise that facilitates moisture removal and increases the chemical reaction and consequently affects the output voltage of the battery is not considered.

On the other hand, CFD-based models have been widely used to analyze the mass and charge transfer mechanisms and their spatial distribution in a single cell, but with the BOP and the components of the power supply, Limited. In addition, the exponential increase in computation time required for unsteady analysis hampers the application of the model for the stack.

The models used in this specification are based on empirical formulas and take into account three major effects: moisture balance in the membrane, gas dynamics in the gas diffusion layer, and temperature distribution in the cell as described below.

The cell is formed by the connection of each model constituting the layers. The I-V characteristics are determined by the difference between the open-circuit voltage and the resistance and potential at the membrane, the driver over-current at the cathode-side catalyst, and the over-potential including the concentration over-potential. The relationship for one cell is written as a function of physical parameters such as reactant partial pressure, temperature, current and film moisture content. The output characteristics of the stack are estimated by multiplying the output of one cell by the number of cells.

The dynamics of a fuel cell system include mass flow of air and water. The supplied air flows through the GDL before reaching the gas flow path and the catalyst, at the same time absorbing moisture from the humidifier. The water produced in the catalyst is diffused through the membrane. In the film, both absorb moisture from the anode side to the cathode side. The heat generated by the chemical reaction and charge transfer elevates the temperature in the cell. All of these changes affect the dynamic behavior of the cell. More improvements in dynamics are made taking into account the following three effects: 1) moisture kinetics in the membrane, 2) partial pressure drop in the GDL, and 3) temperature change.

The moisture content in the film determines the proton conductivity. The kinetics of the moisture content are explained by the two effects of electroosmotic driving force due to different electrochemical potentials at the anode and the cathode and diffusion caused by the moisture concentration gradient at the boundary between the anode and the cathode. Considering the water mass flowing from the boundary of the film layer, the dynamics of film moisture concentration was developed to the following equation. Here, C is the mass concentration (kg · m ^-3 ), M is the molar mass (kg · mol ^-1 ), b is the parameter (reference PC and Wasynczuk. (1989) O, Electrochemical Motion Devices, McGraw-Hill Book Company, New York), ρ is the membrane dry density, and A _cell is the fuel cell area (in m ² ).

 Reactants entering the cell diffuse through the GDL before reaching the catalyst bed, and have a significant impact on the overall kinetics of the reactants. This diffusion effect is reflected by using the following mass continuity and the Stefan-Maxwell equation.

Here, i, k∈ (1,3) are for summing partial pressure of each kind, p ₁ is oxygen partial pressure, p ₂ = p _sat (T), and p ₃ is partial pressure of steam and nitrogen , And the diffusion coefficient p _ca D _ik includes the cathode pressure p _ca. The parameters τ and ε _g are constants to represent the pore curvature of the GDL.

If the cell is isotropic in thermal properties and is made up of regular cubic layers, then according to the law of conservation of energy, the total energy change in the test volume is equal to the sum of energy exchange in the boundary and internal energy sources. In fact, energy exchange at the boundary occurs by a) conduction across the cell and b) bipolar plates with cooling water, reactants, and convection between the water and the two factors. The thermodynamic behavior can thus be represented by the following energy conservation laws.

The internal energy source consists of the entropy loss and the chemical energy required to overcome the overvoltage barrier in the two catalyst beds. In addition, others are resistance losses caused by the movement of electrons and protons in the cell. The internal energy source is expressed by the following equation.

Here, Δs is -65.0 (J · mol ^-1 K ^-1 ) and ν _act is the model of the performance modeling of the Amphlett, JC, Baumert, RM, Mann, RF, Peppley, BA and Roberge, Ballard Mark IV solider polymer electrolyte fuel cell, J. Elecrochem. Soc., 142 1 9-15, and R _membr is membrane resistance.

The air supply must continuously supply air to the fuel cell stack as the load changes. The air supply device consists of four sub-devices, an air supply, a humidifier, an inlet and an outlet manifold with a regulator to regulate the pressure in the stack.

Thanks to the efficiency of the device, blowers are widely used to supply air. The humidifier herein simplifies to an ideal without any associated kinetics or energy loss.

The blower is typically driven by an electric motor. The dynamic characteristics of the blower unit are described by the sum of all inertia moments of the motor and the impeller and the torque generated by the motor. Here, the torque τ _{bl, m} (J) generated by the motor is determined by the stator resistance R _{s, bl, m} (ohm), the bundle joint φ _{bl, m} (V 揃 s 揃 rad ^-1 ) And is a function of the number of poles n _{bl, m, pl} with the stator voltage V _{bl, m} (V).

Where ω is the angular velocity (rad · s ^-1 ), J is the rotational inertia (kg · m ² ), η is efficiency, p is pressure (Pa), and ρ is air density (kg · m ^-3 ). The flow rate of the air blower is a function of angular velocity and pressure, and the efficiency is expressed as a function of flow rate and angular velocity.

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The parameters of the blower were extracted from the specification data and the specification of PADT (Phoenix Analysis & Design Technologies), which contains the overall efficiency for flow parameters and head parameters.

The dynamic properties of the inlet and outlet manifold pressures are described as follows using the mass conservation equations.

The thermal circuit must be capable of discharging excess heat generated in the stack. The circuitry is configured to introduce cooling water into the fan to pump the cooling water into the radiator to exchange heat with the surrounding medium, to increase the efficiency of thermal convection, and to flow into the reservoir to store and thermally isolate the cooling water. Valve. Finally, the cooling pump is adapted to supply cooling water to the heat source.

The opening amount of the bypass valve is assumed to be linearly related to the coefficient k, the cooling water temperature at the storage inlet is k, the cooling water temperature at the stack outlet (T _{st, c, out} ), and the cooling water at the radiator outlet Is expressed as a function of temperature (T _{rad, c, out} ) as:

The radiator behavior is described by the thermodynamic principle. In Kroger, DG, (1984) Radiator Characterization and Optimization, SAE paper 840380, the radiator heat transfer coefficient (h _rad ) (kW · m ^-2 ℃ ^-1 ) and the radiator pressure The empirical formula for expressing the drop (p _r ) (kPa) as a function of air flow (W _air ) (kg · s ^-1 ) is as follows.

If the heat of the cooling water is completely transferred to the radiator without loss, the heat capacity of the cooling water is equal to the heat capacity of the radiator. Thus, the radiator outlet cooling water temperature is expressed as a function of the heat convection caused by the radiator geometry and the temperature difference between the ambient air and the air leaving the radiator as follows.

Here, Fr _area refers to the front surface area (m ² ) of the radiator _, and T _{rad, c, in} refers to the radiator inlet cooling water temperature. The electric power for the fan is calculated by the following equation according to the thermodynamic relation between the pressure drop and the air flow rate.

Here, p _fan refers to the electric power (W) of the fan.

After convection has caused heat exchange in the radiator, the reservoir must be thermally insulated. The change in heat in the storage is the sum of the heat transferred by the coolant and the heat exchanged around. Therefore, at the end of a given period, the storage outlet coolant temperature (T _{res, c, out} ) (˚K) is expressed by the following equation.

Here, T _{res, p} is a storage temperature (K) in the previous step, Δt is the duration (sec), M _res is the same as the weight (kg) of the cooling water in the _reservoir, T _{res, c, in} the storage inlet water Is the temperature (K), and h A _pl means the heat transfer (J · K ^-1 ) around the associated flow.

Assume that all the heat generated in the stack is completely transferred to the cooling water. Then, the cooling water flow rate is expressed by the following relation with the heat source.

In equilibrium, the excess heat emitted by the cooling water is equal to the heat stored by the reservoir and the heat exchanged with the surroundings in the radiator. First, assuming the maximum coolant flow rate, the temperature drop along the coolant flow path can be calculated by considering the fact that the maximum heat generated in the stack must be discharged by the coolant flow rate. If the catalyst temperature is 80 ° C, it is assumed that the temperature gradient from the catalyst to the cooling water passage reaches 8 ° K at the maximum load current, so that the outlet temperature of the cooling water is 72 ° C. Thus, the inlet temperature is obtained at a temperature drop of 12 ° C and a maximum flow rate of 3 kg / sec. The heat transfer coefficient of the radiator and the volume of the reservoir are selected based on the maximum heat capacity to be stored and discharged.

2 is a block diagram illustrating a typical control device 200 including two controllers for controlling air and cooling water flow rates. The apparatus 200 includes a hydrogen tank 210 coupled to the fuel cell stack 240 for fluid flow through a valve 235, such as a pressure relief valve. The hydrogen tank 210 supplies hydrogen (W _H2 ) to the fuel cell stack 240.

The blower 220 is coupled to flow the fuel cell stack 240 to supply _air W _air to the fuel cell stack 240 (in some embodiments, through the inlet manifold 225) have. A portion of the air pressure P _im may be diverted from the inlet manifold 225 via the stator 230 to the valve 235. The air supply rate is controlled by the air supply controller 215. The air supply controller 215 uses the interpolated map data using the reference load current I _ref and the function f (I _st ) in the controller 217 to calculate the voltage V _bl of the blower 220 And controls the air supply to the fuel cell stack 240 by this.

The coolant pump 280 couples the reservoir 270 to the fuel cell stack 240 so that the coolant W _c can flow from the reservoir 270 to the fuel cell stack 240. The radiator and fan 260 cool the cooling water (W _{c, an} , W _{c, ca} ) at the anode and cathode sides of the fuel cell stack 240 and supply cooled cooling water to the storage 270 for later use And is connected to the reservoir 270 at the outlet side of the fuel cell stack 240 so that the fluid can flow. The flow rate of the cooling water to the fuel cell stack 240 is controlled by the cooling water flow control device 250. Coolant flow controller 250 uses logic element 255 to compare the reference coolant temperature T _{c, ref with} the average coolant temperature T _{c, ave} from the stack. This comparison is used by a proportional-integral (PI) controller 257 to determine and supply a control signal to the coolant pump 280, thereby controlling the supply of coolant to the fuel cell stack 240. The average coolant temperature (T _{c, ave} ) is obtained using temperature sensors located downstream of the fuel cell stack 240 and upstream of the coolant flow control device 250. The sensors transmit cooling water temperatures ( _{Tc, an} , _{Tc, ca} ) from the anode side of the fuel cell stack and from the cathode side of the fuel cell stack to the logic elements 245, 253, The temperatures are added and divided in half to form the temperature (T _{c, ave} ).

Additional emissions, such as water, are directed through exit manifold 285, valve 287, and stator 290 to exit fuel cell stack 240 and apparatus 200.

The purpose of air flow control is to maintain an optimal oxygen excess rate and, as a result, to prevent oxygen shortage that can occur during abrupt changes in the current load. Here, the oxygen excess rate is defined as the ratio of oxygen supplied to the consumed oxygen, which depends on the stack current. The oxygen supplied to the stack is directly proportional to the air flow delivered by the air blower, and ultimately directly proportional to the magnitude of the blower motor voltage. Therefore, a controller for the air flow rate, that is, a static feed-forward (sFF) controller, is designed using a polynomial interpolating map data. The data includes an optimal relationship between the stack current and the blower voltage required to keep the excess oxygen rate at 2, which is different from that of other designers (Domenico, AD, Miotti, A., Alhetairshi, M., Guezennec, YG, Rajagopalan, SSV and Yurkovich, S., (2006) Multi-variable control for an automotive traction PEM fuel cell system, Proc. The 2006 American Control Conference, Minneapolis, Minnesota; Rodatz, P., Paganelli, G and Guzella, L (2003) Optimization Air Supply Control of a PEM Fuel Cell System, IEEE Proc. American Control Conference; Vahidi, A., Stefanopoulou, AG and Peng, Cell system, IEEE Proc. American Control conference). As shown in FIG. 7, the performance of the control is excellent, especially in the case of excessive disturbance, the oxygen excess rate discharge behavior. However, the model used for the design of the controllers assumes that the operating temperature of the stack is constant, which does not correspond to the actual behavior of the stack during operation.

The present invention provides a new control strategy for temperature circuitry that reduces temperature rise in the catalyst during dynamic load changes, minimizes power consumption, and optimizes oxygen deficiency in the air supply. The model for a single cell considers the geometry of the gas diffusion layer, the effect of temperature drift, and consequently the moisture content of the proton conducting layer in the film.

In some embodiments, the temperature circuit includes a bypass valve, a radiator having a fan, a reservoir, and a coolant pump. In some embodiments, the air supply device includes a blower and inlet and outlet manifolds. Based on the component model, control for air and cooling water flow under the aspect of excess power and temperature rise in the catalyst as well as consuming power are designed and compared. In particular, the coolant flow rate is controlled such that the excess heat of the battery in the load configuration is estimated and feed-forwarded to a cooling water control loop that compensates for this excess heat. Conventional PI controllers and state feedback control methods for temperature circuits are designed. A heat source item that depends on the load current is fed forward to the closed loop and the temperature effect on the air flow rate is compensated.

The dynamics and performance of the designed controllers are evaluated and analyzed by simulation using a dynamic fuel cell device model in a multistage current and current profile measured by a Federal Urban Driving System (FUDS). The results show that the control strategy of the present invention not only treats the power consumed for the operation of the air and coolant pumps but also relieves the temperature rise and oxygen deficiency in the catalyst bed.

The control for the cooling water flow is based on the energy equation. In fact, a stack of cells can be regulated to one thermal mass with one heat capacity. If heat exchange by radiation is negligible and the stack temperature is equal to the average of the stack outlet cooling water temperatures at the anode and cathode sides, the temperature change in the stack is equal to the sum of the heat source items and the heat exchanged with the cooling water and ambient , Which appears as follows.

Here, m _st Cp _st is the heat capacity of the stack (J · K ^-1 ), W _c is the cooling water flow (kg · s ^-1 ) as a control variable, and Q _sou is the internal energy source J · s ^-1 ). Due to the non-linearity of the equation in the above one mass of thermal stack and storage model, Taylor expansion is used to obtain linear equations at the operating point, where the cooling water temperature and flow rate are 64 ° C and 0.93 kg / sec, respectively. The stack current and voltage are 140A and 198V, respectively. The state equations and variables are defined as follows.

The linearized equation is transformed as follows in the Laplace domain.

Here, the superscript () indicates a constant at the operating point.

In fact, the first term is a heat source item, while the third and fourth terms show constant values. The transfer function between the stack temperature and the cooling water flow results in a first order differential equation used for the design of a classical PI controller.

Here, the heat source item Q _sou is regarded as a disturbance of the thermal device, which should be suppressed as soon as possible. Thus, the two gain values of the PI controller are selected with a bandwidth of the closed circuit three times higher than the bandwidth of the thermal device and a damping ratio of 0.707. The resulting gain values are K _p = 0.2734 and K _I = 0.0443 (sec ^-1 ), respectively.

When the current drawn from the stack changes abruptly, the heat generated in the stack tends to follow the current with a time constant. However, the typical cooling water control simply does not remove this heat completely because it detects the temperature at the cooling water outlet. As a result, the removed heat is less than the generated heat.

As a countermeasure, the present invention estimates the temperature rise in the stack directly caused by the current load, and feeds this information to the temperature control circuit. The relationship between current and stack temperature yields the following transfer function.

Here, R _act represents the equivalent resistance for the activation overvoltage.

On the other hand, the temperature of the cooling water control circuit is set to be lower than the temperature of the stack for the removal of heat from the stack, which changes the temperature in the air flow path and consequently changes the pressure. As the temperature in the passage lowers, the pressure drop in accordance with the ideal gas law at a given volume and the pressure difference to the inlet manifold then becomes large. As a result, the mass flow rate at the inlet of the stack is determined by the nozzle equation (Pukrushpan, JT, Peng, H. and Stefanopoulou, AG, (2002) Simulation and Analysis of Transient Fuel Cell System Performance Based on Dynamic Reactant Flow Model, 01, 2002 ASME International Mechanical Engineering Congress & Exposition, New Orleans, LA), resulting in an increase in the oxygen excess rate. The increased air mass flow rate can be reduced by adding a compensator to the control strategy that compensates for the flow rate with respect to the coolant temperature rise and the current determining the consumed oxygen. Because of the non-linear relationship between the blower voltage and other currents and temperatures at the optimal oxygen excess rate, a set of data is obtained by multi-running the entire model under different currents and temperatures, .

In one embodiment of the present invention, an air and cooling water control device is provided. The apparatus includes a heat source, an air source, an air supply controller, a coolant source, and a coolant control device.

In some embodiments, the heat source includes an air inlet, a cooling water inlet, a cooling water inlet, and a cooling water outlet coupled to allow the fluid to flow through the heat source. In some embodiments, the heat source receives air through the air inlet, generates heat corresponding to the input of the air, receives cooling water through the cooling water inlet, guides the input cooling water to the cooling water outlet, To the cooling water that has been input, thereby removing part of the generated heat from the heat source when the cooling water is guided out of the heat source through the cooling water outlet. In some embodiments, the heat source is a fuel cell stack. For example, the heat source may be a PEM (Polymer Electrolyte Membrane) fuel cell stack. However, the present invention is designed to be equally applicable to other heat sources.

The air supply source is coupled to the air inlet of the heat source so that the air can be supplied to the heat source. In some embodiments, the air supply control device is adapted to regulate the air flow rate from the air source to the heat source based on dynamic feedback temperature characteristics from the heat source.

The cooling water supply source is coupled to the cooling water inlet of the heat source so that the cooling water can be supplied to the heat source. In some embodiments, the cooling water control device is adapted to regulate the flow rate of the cooling water supplied to the heat source based on the estimated feed-forward heat source characteristics. In some embodiments, the cooling water control device is adapted to regulate the cooling water temperature supplied to the heat source based on the dynamic feedback temperature characteristic.

In some embodiments, the apparatus includes a fuel source coupled to allow the fluid to flow to the heat source and adapted to supply fuel to the heat source. For example, in some embodiments, a hydrogen tank is coupled to the fuel cell stack to allow fluid to flow to supply hydrogen to the fuel cell stack.

Although the present specification discloses a detailed configuration of the dynamic feedback temperature data and the estimated feedforward heat source temperature data used in certain control / regulating mechanisms, this control / regulating mechanism is not limited to other data that have not been explicitly discussed, Both data and untested data may be used. The dynamic feedback temperature data can be any data provided through the feedback circuit and shows the latest temperature state of some form of the heat source. For example, in some embodiments, the dynamic feedback temperature characteristic includes information indicative of the temperature of the cooling water measured at the cooling water outlet of the heat source. The estimated feed-forward heat source characteristics include an estimate of the extreme heat of the heat source in the load configuration. The feedforward controller can adjust the flow rate of the cooling water based on the load shape and the interpolated map data.

In some embodiments, the cooling water control apparatus includes at least one controller selected from the group of controllers consisting of a proportional-integral controller and a state feedback controller.

Coolant temperature is designed to be adjusted in several ways. In some embodiments, the apparatus includes a cooling water reservoir adapted to store cooling water to be guided to a heat source and through a heat source, a cooling water pump configured to pump cooling water from the cooling water reservoir to a heat source, the cooling water flow rate being controlled by a cooling water control device, A cooling device adapted to cool the cooling water from the heat source and providing the cooled cooling water to the cooling water reservoir and a bypass valve adapted to regulate the amount of cooling water supplied from the heat source to the cooling device. In some embodiments, the adjustment of the amount of cooling water is based on dynamic temperature information around the heat source.

In another embodiment of the present invention, a method of controlling a heat source device is provided. In some embodiments, the heat source device includes a heat source, a load configuration for the heat source, an air source, and a coolant source.

In some embodiments, the method includes causing air to flow from the air source to the heat source at an air flow rate. In some embodiments, the air flow rate is adjusted based on dynamic feedback temperature characteristics. The heat source generates heat in response to receiving air from an air supply source. The cooling water flows from the cooling water source to the heat source and through the heat source with the cooling water flow rate and the cooling water temperature. In some embodiments, the cooling water flow rate is adjusted based on dynamic feedback temperature characteristics and the cooling water temperature is adjusted based on feedforward heat source characteristics. The heat source transfers part of the generated heat to the cooling water, thereby removing part of the heat generated when the cooling water flows out of the heat source from the heat source.

All design changes discussed herein for the device of the present invention apply equally to the above method.

The present invention is capable of using any combination of air flow rate, cooling water flow rate, and cooling water temperature control mechanisms disclosed herein.

The following description is given to enable a person having ordinary skill in the art to make or use the present invention, and the patent application and its requirements are provided in connection with each other. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the generic principles herein may be applied to other embodiments. Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and features described herein.

This specification provides several embodiments of the present invention. Any one feature of any one embodiment is contemplated to be combinable with any feature of the other embodiment. As such, all of the mixed features of the illustrated embodiments are included in the scope of the present invention.

The state equation obtained above shows a multi-input, multi-output structure in which the two control input variables, coolant temperature and coolant flowrate, are dependent on each other. This dependence can be minimized if the time constants of the two feedback circuits are set to have different orders. Then, the temperature in the stack can be controlled by the cooling water flow rate independently of the cooling water temperature controlled by the opening amount coefficient (k). The following equation includes the relationship between the stack temperature and the cooling water flow rate, and the transfer function is as follows.

The following equation contains the relationship between the temperature of the reservoir and the coefficient for opening of the bypass valve, and the transfer function is as follows.

Similarly, the gain values for the PI controller are chosen such that the bandwidth of the closed circuit is five times higher than the time constant of the coolant flow feedback external circuitry. In addition, the damping ratio is set to 0.707. The resulting gain values are K _{p, b} = 0.1902 and K _{I, b} = 0.0546 (sec ^-1 ), respectively.

The classic PI controller did not consider consuming power as a control target in the coolant pump, although it would discharge enough heat and effectively suppress the temperature rise in the bed. One alternative is to use state feedback control, where the wasting power wasted in the coolant pump can conveniently be regarded as one of the control goals. On the other hand, the consumption power of the cooling water pump is directly proportional to the cooling water flow rate. Therefore, the coolant flow rate is included as a parameter of the following cost function. The gain values are optimized by a linear quadratic regulator (LQR) method, which basically sums the square of the error.

While Q _x represents a weighting matrix that amplifies the error of the control target, the other weighting matrix R is used to suppress the effects of the processed variables.

The state equation of the controller represents a 2 * 2 matrix, in which the variables are connected to each other. Separation into two circuits is accomplished by assigning different time constants to the two closed circuits. In fact, while the storage temperature is strongly influenced by the valve opening factor rather than the coolant flow, the valve opening factor coefficient does not directly affect the stack temperature dynamics. Here, the time constant of the transfer function between the stack temperature and the cooling water flow rate is set five times faster than the time constant of the transfer function between the stack temperature and the valve opening amount coefficient.

On the other hand, the integrator is needed to suppress any steady-state error. Therefore, the error of both closed circuits is defined as a new state variable considered in the cost function as follows.

Where Q _I is a weighting matrix for the integrator. Then, the rule for the optimal control input is obtained as follows.

Here, the controller gain is. P is the year of the Algebraic Riccati Equation given as:

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If the weighted matrix R is greater than the weighted matrix Q, the role of the coolant flow in the cost function increases, and consequently the gain values of the controller are chosen to minimize power consumption. After several iterations with different weighting factors, the optimal control matrices K _p and K _I are given by:

The heat generated in the stack tends to follow the current from the stack. Current-dependent heat is considered disturbance in the control circuit, which is not completely removed by typical cooling water control which measures the temperature at the cooling water outlet. As a result, the heat released is smaller than the heat produced. The countermeasure is to estimate the temperature rise in the layer directly related to the magnitude of the current load and feed it forward to the temperature control circuit shown in Figures 5A and 6A. The relationship between current and stack temperature yields the following transfer function, where v _act represents the activation potential.

However, all previously announced air supply control designs assumed a constant cell operating temperature. In fact, the temperature distribution at each layer across the plane changes due to the various heat sources of irreversible energy generated in the chemical reaction and the loss of the line associated with charge transfer. In order to allow the discharge of heat to occur in the stack, the temperature of the cooling water control circuit is set lower than the temperature in the stack, thereby changing the temperature in the gas flow path. As the temperature in the passages decreases, the pressure drop over the ideal gas law at a given volume and the pressure differential to the inlet manifold at that time increases. On the other hand, at the inlet of the stack, the mass flow rate increases with the nozzle equation and consequently the oxygen excess rate increases. The surplus air is reduced by an additional factor depending on the coolant temperature as well as the current which determines the oxygen consumed in the control. Due to the nonlinear relationship between the blower voltage and the different currents and temperatures at the optimal oxygen excess rate, a set of data is obtained by multiplying the entire model under different currents and temperatures used to compensate for the effects.

FIG. 3 shows a generalized embodiment of an air and cooling water control device 300 having a feed-forward cooling water controller and a temperature-compensated air source in accordance with the principles of the present invention. The apparatus 300 includes a heat source 340, an air source 320, an air supply controller 315, a coolant source (including a coolant pump 380 and a fluid reservoir 370), and a coolant control device 325 .

The heat source 340 includes an air inlet 341 coupled to the air supply source 320 to allow the fluid to flow therethrough, a cooling water inlet 342 coupled with the cooling water supply source to flow the fluid, And includes a cooling water inlet 342 and a cooling water outlet 343 coupled to flow the fluid. The heat source 340 is configured to receive air through the air inlet 341 and generate heat in response to the input of air. The cooling water is inputted through the cooling water inlet 342, The cooling water is guided to the cooling water outlet 343 and a part of the generated heat is transferred to the inputted cooling water so that when the cooling water is guided out of the heat source 340 through the cooling water outlet 343, To remove a portion of the heat generated from the heat source. In some embodiments, the heat source 340 includes a PEM fuel cell stack. However, in some embodiments, the heat source 340 includes other types of fuel cell stacks or other devices in lieu of the fuel cell stacks or other devices in place of the fuel cell stacks.

The air supply source 320 is coupled to the air inlet 341 of the heat source 340 to supply the air to the heat source 340. In some embodiments, the air source 320 is an air compressor or blower.

The air supply control device 315 is coupled to the air source 320 to operate by means of a rigid wire or by a wireless connection and is connected to the air supply source 320 from the air supply source 320 based on the dynamic feedback temperature characteristic of the heat source 340 So as to control the air supply to the heat source 340. This dynamic feedback temperature characteristic represents the temperature of one or more elements of the heat source. In some embodiments, the dynamic feedback temperature characteristic includes the cooling water temperature from a heat source, which is ideally determined by one or more temperature sensors coupled to the cooling water outlet of the heat source 340. This temperature information is determined by the sensors when the cold water number comes into contact with the sensors and is transmitted to the air supply controller 315 which determines the appropriate control signal for controlling the air supply 320 It is operated and used by the controller. Based on the temperature information about the heat source 340, the air supply control device 315 will regulate the amount of air to be supplied to the heat source 340. Current control for the air flow rate does not take into account the effect of the temperature of the heat source element or cooling water on the air flow rate, which results in more consumption of power. The compensation of the temperature to the air flow rate reduces the power consumption. In addition to the feedback temperature information, the air supply control device may also be based on the load shape applied to the apparatus 300 to control the air supply 320.

The cooling water supply source is coupled to the cooling water inlet of the heat source 340 to supply the cooling water to the heat source 340. In some embodiments, the cooling water source includes a fluid reservoir 370 adapted to store cooling water and a cooling water pump 380 adapted to pump cooling water from the fluid reservoir 370 to a heat source. The flow rate of the cooling water is controlled by the cooling water control device 325. In some embodiments, a cooling device 360, such as a radiator and a fan, is provided to cool the cooling water from the heat source 340 and provide cooled cooling water to the cooling water reservoir 370. In some embodiments, the amount of cooling water supplied from the heat source 340 to the cooling device 360 may be regulated by regulating the amount of cooling water bypassing the cooling device 360 on the way from the heat source 340 to the cooling water reservoir 370 A bypass valve 350 is provided. In some embodiments, such regulation is based on dynamic temperature information around the heat source 340.

The cooling water control device 325 is adapted to control at least one cooling water characteristic of the control device 300. An example of such cooling water characteristics is a cooling water flow rate (which can be controlled by controlling the cooling water pump 380) supplied to the heat source 340, a cooling water temperature that is supplied to the heat source 340 Or by controlling the amount of cooling water from the heat source 340 (e.g., by changing the opening angle of the bypass valve).

Control of the coolant flow rate is based on the estimated feed-forward heat source characteristics. This estimated feed forward heat source characteristic is a temperature profile based on the load shape applied to the device 300. [ Algorithms are used to calculate the virtual temperature profile and compensate it by feedforward control. In some embodiments, the load configuration is the same as the load configuration used by the air supply controller 315 to control the air supply 320, and is transmitted from the air supply controller 315 to the cooling water controller 325 . Additionally or alternatively, the load configuration may be provided independently of the air supply control device 315 (i.e., it need not be supplied to the cooling water control device 325 by the air supply control device 315). ).

Coolant temperature control is based on the dynamic feedback temperature characteristics discussed above. In this regard, the device 300 may use a similar sensor and communication characteristic to communicate information about the heat source temperature to the cooling water control device 325. [ In some embodiments, this information may be based on the actual temperature value measured at the cooling water passage outlet of the heat source 340. Additionally or alternatively, such information may be equally based on other measures or data.

In addition to the cooling water, additional materials (byproducts, air, fuel, etc.) are output through one or more output lines coupled to the heat source 340 to allow fluid to flow.

FIG. 4 shows a more specific embodiment of the air and cooling water control device 400 using the PI controller according to the principles of the present invention. The apparatus 400 includes a fuel cell stack 440, an air source 420 (such as a blower), an air supply controller 415, a coolant source (in some embodiments, a coolant pump 480, a fluid reservoir 470 ), And a radiator and fan 460), and a coolant flow control device 450.

The fuel cell stack 440 includes an air inlet coupled to the air supply source 420 for flowing the fluid, a cooling water inlet coupled to the cooling water supply source to allow the fluid to flow therethrough, And a cooling water outlet coupled to allow the fluid to flow into the cooling water inlet.

The air supply source 420 is coupled to the air inlet of the fuel cell stack 440 so as to allow the air to flow to the fuel cell stack 440. The air supply control device 415 is operatively coupled to the air source 420 via a rigid wire or by a wireless connection and is connected to the air supply 420 from an air supply 420 based on dynamic feedback temperature characteristics from the fuel cell stack And adjusts the air supply to the heat source 440. This dynamic feedback temperature characteristic represents the temperature of one or more elements (e.g., catalyst) of the fuel cell stack. In some embodiments, the dynamic feedback temperature characteristic includes the cooling water temperature from the fuel cell stack, which is ideally determined by one or more temperature sensors coupled to the cooling water outlet of the fuel cell stack 440. This temperature information is determined by the sensors when the coolant is brought into contact with the sensors and is transmitted to the air supply controller 415 which is connected to the controller to determine the appropriate control signal for controlling the air supply 420 Are manipulated and used. Based on the temperature information (T _{c, ave} ) around the fuel cell stack 440, the air supply control device 415 will regulate the amount of air to be supplied to the fuel cell stack 440. In some embodiments, this temperature information is communicated to the compensator 416 in the air supply control device 415. The compensator 416 uses this temperature information together with other information, such as the reference current I _ref , to compensate for the dynamic state of the fuel cell stack 440. The air supply control device 415 interpolates the map data using the reference load current I _ref and using the function f (I _ref ) in the controller 412. In some embodiments, a logic element 414 is used to process the results from the controller 412 and the compensator 416.

The coolant supply source is coupled to the coolant inlet of the fuel cell stack 440 so as to allow the coolant to flow and to supply the coolant to the fuel cell stack 440. In some embodiments, the coolant supply includes a coolant reservoir 470 adapted to store coolant and a coolant pump 480 configured to pump coolant from the coolant reservoir 470 to the fuel cell stack 440. The flow rate of the cooling water is controlled by the cooling water flow control device 450. In some embodiments, a cooling device 460, such as a radiator and a fan, is provided to cool the cooling water from the fuel cell stack and provide cooled cooling water to the cooling water reservoir 470.

The cooling water flow control device 450 is adapted to regulate the flow rate of the cooling water supplied to the fuel cell device 440, which is controlled by controlling the cooling water pump 480. Control of the cooling water flow rate is based on the estimated feed forward heat source characteristics discussed above. This estimated feed forward heat source characteristic is a temperature shape based on the load shape applied to the apparatus 400. [ Algorithms are used to calculate the virtual temperature profile and compensate it by feed-forward control. In some embodiments, this load configuration is the same as the load configuration used by the air supply control device 415 to control the air supply 420, and thus from the air supply control device 415 to the cooling water flow control device 450 ). ≪ / RTI > In some embodiments, the coolant flow control device 450 interpolates the map data using the reference load current I _ref and using the function g (I _ref ) in the controller 452. In some embodiments _, a logic element 454 is used to process the results from the controller 452 and the coolant reference temperature (T _{c, ref} ). The logic element 454 passes its result to a logic element 456 which merges the dynamic feedback temperature characteristic from the fuel cell stack 440 before delivering the result to the PI controller 458. The PI controller 458 controls the operation of the coolant pump 480 and thereby regulates the coolant flow rate to the fuel cell stack.

In some embodiments, the apparatus 400 includes a hydrogen tank 410, an inlet manifold 430, an outlet manifold 485, stators 435, 490 (not shown), similar to the configuration of the corresponding elements shown in FIG. ), And valves 437 and 487.

5A shows another embodiment of an air and coolant control apparatus 500A using a PI controller and a bypass valve in accordance with the principles of the present invention. In some embodiments, the apparatus 500A includes a hydrogen tank 510 having similar connections and functions, an air source 520, an air supply controller 515, a controller 512, a logic element 514, a comparator 516 ), A cooling water flow control device 550, a controller 552, logic elements 554 and 556, a PI controller 558, a cooling water pump 580, a cooling water reservoir 570, a radiator and a fan 560, A battery stack 540, an inlet manifold 530, an outlet manifold 585, stators 535 and 590, and valves 537 and 587.

Device 500A includes a bypass valve 545 coupled to allow fuel to flow between the fuel cell stack 540 and the radiator and the fan 560 and a bypass valve 542 coupled to the bypass valve 545 And further includes a bypass valve control device 565. The bypass valve 545 is connected to the fuel cell stack 540 that bypasses the radiator and the fan 560 on the way to the cooling water reservoir 570 from both the radiator and the fan 560 to the cooling water from the fuel cell stack 540. [ To control the amount of the cooling water to be supplied from the cooling water supply unit. In some embodiments, this adjustment is based on dynamic temperature information around the fuel cell stack 540.

The bypass valve control device 565 is adapted to control the amount of cooling water passing or bypassing the radiator and the fan 560 from the fuel cell stack 540. As described above, the bypass valve control device 565 can control the bypass valve 545 based on dynamic temperature information around the fuel cell stack 540. For example, the temperature sensors may determine the temperature of the cooling water stored in the cooling water reservoir 570. This temperature information T _res is then passed to the bypass valve controller 565 where they are stored in the fuel cell stack 540 by a logic element 557 to determine the degree of temperature change Is compared with the storage temperature (T _{res, ref} ). The result is communicated to the PI controller 569 and the PI controller 569 calculates the appropriate ratio k of cooling water to be cooled before it reaches the cooling water reservoir 570 (i.e., by passing through the radiator and fan 560) . The remaining portion (1-k) of the cooling water bypasses the cooling device (560). The PI controller 569 can thus communicate a control signal to the bypass valve 545 to control the valve.

Figure 5B shows another embodiment of the air and coolant control device 500B, which is a variation of the device 500A of Figure 5A. The apparatus 500B has the same components and functions as those of Fig. 5A except that the cooling water flow control device 550 does not merge the feed-forward heat source characteristics. Instead, it uses dynamic feedback temperature characteristics to determine the appropriate cooling water flow rate without applying the estimated load geometry.

6A shows another embodiment of an air and coolant control apparatus 600A using a status feedback and integral controller and a bypass valve in accordance with the principles of the present invention. In some embodiments, the apparatus 600A includes a hydrogen tank 610, an air source 620, an air supply control device 615, and an air supply controller 620, which are similar in construction to the corresponding elements shown in FIG. A controller 612, a logic element 614, a comparator 616, a coolant pump 680, a coolant reservoir 670, a radiator and fan 660, a bypass valve 645, a fuel cell stack 640, Manifold 630, outlet manifold 685, stators 635 and 690, and valves 637 and 697. [ However, the apparatus 600A has replaced the cooling water flow control device 550 and the bypass valve control device 565 with the integral control device 655 and the state feedback control device 650. [

The integral controller 655 calculates the actual average temperature of the cooling water from the fuel cell stack 640 and the reference cooling water temperature T _{c, ref} , the reference storage temperature T _{res, ref} , the actual storage temperature T _res , T _{c, ave} ). ≪ / RTI > The result (q) is passed to the integral controller 658.

The state feedback controller 650 uses the state feedback controller 652 to process the actual storage temperature T _res and the actual average temperature T _{c, ave} of the cooling water from the fuel cell stack 640. The result is passed to a logic element 654 which processes the result together with the reference temperatures T _{c, ref} , T _{res, ref} and sends the result to the logic element 677 . Logic element 677 processes this result with the results from integral controller 658 to determine the ratio k of cooling water from fuel cell stack 640 that must pass through radiator and fan 660. The control signal is then passed to the bypass valve 645 to indicate this ratio.

The result of logic element 677 is also passed to logic element 679 where the result is processed to determine the appropriate cooling water flow rate with the estimated feed forward heat source characteristics from controller 675. Once the appropriate coolant flow rate is determined, a signal is communicated to the coolant pump 680 to adjust the coolant pump 680 accordingly.

6B shows another embodiment of air and cooling water control apparatus 600B, which is a variation of apparatus 600A of FIG. 6A. The apparatus 600B has the same components and functions as those of Fig. 6A except that the feed-forward heat source characteristic is not incorporated into the cooling water flow rate control. Instead, it uses dynamic feedback temperature characteristics to determine the appropriate cooling water flow rate without applying the estimated load geometry.

In order to optimize air flow rate, cooling water flow rate, and / or cooling water temperature, the estimated feed forward heat source characteristics and dynamic feedback temperature characteristics are designed to be used in any combination.

Simulations are conducted to analyze the dynamic behavior of the stack with air supply, thermal devices, and associated control strategies. The dynamics of the responses in moisture content, temperature change, oxygen excess rate, and load current in the film are analyzed below. The parameters and reference data for the selected model are described in the table of FIG. 7, which is an experimental value in part. All models were coded by the given block in MATLAB / Simulink.

9 is a graph comparing the moisture content of the membrane between the experimental model and the proposed model at the stepped load current shown in FIG. First, the moisture content of the film depends on the relative humidity determined by the standard vapor pressure, and the standard vapor pressure depends on the temperature and the vapor pressures on the cathode and the anode side. Since the experimental model assumed a constant temperature of 80 ° C in the membrane, there is no kinetic dynamics of moisture transfer, and consequently the vapor pressure just follows the change in load current. Conversely, water equilibrium and temperature in the membrane have a strong influence on the moisture content of the membrane. When the temperature of the catalyst layer on the cathode side is controlled to 80 캜, the moisture content is increased, and the temperature of the gas passage falls below 80 캜. Then, the saturation vapor pressure decreases and the relative humidity becomes higher. It can be seen that the elevated temperature of the stack due to the high load current leads to a high saturation vapor pressure and low relative humidity on both sides of the cell. As a result, the moisture content of the membrane decreases.

Figure 10 shows the temperatures in the catalyst and coolant passages with and without disturbance feed forward. Since it is difficult to approach the temperature of the catalyst layer during operation, the actual temperature is typically measured in the cooling water at the stack outlet of the anode and cathode sides and then averaged. In consideration of the maximum limit of the temperature in the catalyst and the membrane, the reference temperature for cooling water control is set at 76 占 폚.

When a multi-stage current is applied to the stack, the temperature of the stack rises sharply, especially on the cathode side catalyst, where the cooling water temperature is exclusively controlled for a reference temperature of 76 [deg.] C ( _{Tcatl, see control only} and T _{coolant, control only} ). It should be noted that the catalyst and membrane layers are overheated and damaged.

The temperature difference between the layers can be reduced by feedforwarding (FF) the disturbance with a cooling water control circuit that discharges this excess as soon as possible. The transfer function of the disturbance is. The result of the proposed control strategy is shown in solid line in FIG. 10, where the temperature of the catalyst bed is maintained at approximately 80 ° C. The cooling water temperature follows the change of the catalyst temperature. However, due to the high thermal mass of the stack and the large heat capacity, the instantaneous increase in temperature is not completely suppressed. In addition, a steady-state error caused by the temperature difference between the cooling water passage and the catalyst layer remains. Nevertheless, the cooling of the cell is effective and the heat uptake in each layer is minimized.

Figure 11 shows the effect of cooling water control on the temperature distribution across the plane of the cell. As the magnitude of the current changes step by step from 0.5A to 0.55A, 0.65A, and 0.7A, the stack temperature also increases accordingly. When feed forward is applied, the overall stack temperature is lowered and the catalyst temperature is maintained at 353.5 ° K, which is significantly lower than before. Likewise, the maximum temperature difference between the catalyst on the cathode side and the cooling water passage becomes 4 [deg.] K lower than before. As a result, cooling of the stack is more effective than before.

Figure 12 shows the oxygen excess rate at constant and dynamically varying temperatures with cooling water flow control. Because of the pressure change in the gas flow path caused by the change in stack temperature, the oxygen excess rate is adversely affected by the direction in which the current changes.

Fig. 13 shows a comparison of the oxygen excess rate before and after the compensation of the temperature affecting the air control circuit. Even when the current applied to the stack changes stepwise, the overheating ensures that the oxygen excess rate is maintained at about 2, which means that the power consumed by the blower is reduced.

The comparison between the PI control and the state feedback control shows that the power consumption of the state feedback control at the stepped load current is 5% less than the power consumption of the PI control. However, the dynamic response is greatly improved by the state feedback control. In Fig. 14, the step response of the two controls was simulated with the aforementioned models. The output states are the coolant flow rate and the stack inlet coolant temperature. The rise time of the cooling water flow rate by the state feedback control is 6 seconds, which is four times faster than the rise time by the PI control. Likewise, the rise time of the temperature of the stack inlet cooling water by the state feedback control is three times faster than the rise time by the PI control.

The consumed power is calculated by adding the electric power required to drive the blower and the coolant pump. Control strategies that do not have valves for cooling water and PI control circuitry require 106 kWs, while control strategies with the proposed state feedback control require 100 kWs at multi-stage currents.

Furthermore, the response of the state feedback control was compared with the conventional one using the load shape obtained from the vehicle tested in Federal City Driving Apparatus (FUDS). Figure 15 shows the simulation results of two different control strategies for the current. Even if the cooling water is appropriately controlled around the set reference temperature shown in FIG. 15B, according to the control without FF (feed forward), the maximum temperature in the catalyst layer is 6 占 보다 higher than the temperature of the working stack. 15C shows the temperatures of the catalyst and the cooling water in the case of the feed forward (FF) of disturbance. The maximum value of the temperature for the first 200 seconds is similar to that of the others, but in the subsequent period, the maximum value of the temperature is considerably reduced as compared with Fig. 15B. The oscillation period of the catalyst temperature is reduced, and the thermal energy to be imposed on the thin layer is eventually reduced, which significantly reduces the thermal stress in the layer. Correspondingly, the oxygen excess rate is considerably maintained at the optimum value by compensation, as shown in Fig. 15D.

The present invention presents the design of a temperature control strategy and its effect on dynamics and performance. Controllability is attributed to the use of a dynamic stack model with elements of gas diffusion in the GDL, dynamic moisture balance in the membrane and temperature changes, and air supply and temperature devices.

Improvements in dynamic stack behavior are achieved by adding dynamic moisture and temperature distributions through the membrane and partial pressure drop in the GDL. The results show that the temperature distribution across the plane is asymmetric and the temperature rise is 3-7 ° C, which can potentially damage the layer at high current loads. Therefore, proper control of air and temperature may be required to ensure durability and increase efficiency.

Most strategies focused on optimizing the air supply, where the operating temperature of the fuel cell stack was assumed to be constant. However, it has been proved that the oxygen excess rate changes inversely to the temperature change. Therefore, the ideal oxygen excess rate required to prevent oxygen deficiency was not maintained at the optimal value of 2.

The control strategy of the present invention includes a state feedback control having a compensator for minimizing the temperature effect on the feed forward of the disturbance and the air flow rate. For the design of the temperature controller, the thermal circuit is approximated by a second order device. Classic PI and state feedback controls are used to compare the efficiency of cooling. The results show that the temperature rise in the catalyst can be maintained at acceptable values and durations. In addition, the oversupply rate can be maintained at an optimal value by minimizing the influence of temperature changes in the gas flow passages. As a result, the power consumption of the blower in a multistage load configuration can be reduced by 15% by compensation and by 5% by controlling the bypass valve. The overall reduction in power consumption is ultimately about 7%.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, And all changes to the scope that are deemed to be valid.

1 shows a conventional PEM fuel cell device.

2 shows a conventional air and cooling water control device.

3 shows a generalized embodiment of an air and cooling water control device having a feed-forward cooling water control and a temperature-compensated air supply in accordance with the principles of the present invention.

FIG. 4 shows a more specific embodiment of the air and cooling water control device using the PI controller according to the principles of the present invention.

5A shows another embodiment of an air and cooling water control apparatus using a PI controller and a bypass valve according to the principles of the present invention.

5B shows another embodiment of an air and cooling water control apparatus using a PI controller and a bypass valve according to the principles of the present invention.

6A shows another embodiment of an air and cooling water control apparatus using a state feedback and integral controller and a bypass valve according to the principles of the present invention.

6B shows another embodiment of an air and cooling water control device that uses a status feedback and integral controller and a bypass valve in accordance with the principles of the present invention.

7 is a table showing parameters and reference data for the selected model.

8 is a graph showing a stepwise load current.

9 is a graph comparing the moisture content of the membrane between the experimental model and the proposed model.

10 is a graph showing the temperatures of the catalyst layer and the coolant passage by the cooling water flow control with the feed forward of the disturbance and the cooling water flow control without the disturbance feed forward.

11 is a graph showing the effect of cooling water control on the temperature change of the battery depending on the current in cooling water control without cooling water control with disturbance feed forward and without feedforward of disturbance.

12 is a graph showing a comparison of the oxygen excess rate at constant temperature and dynamically varying temperature.

13 is a graph showing a comparison of the oxygen excess rate before and after the compensation of the temperature affecting the air control circuit.

14 is a graph showing a comparison of the cooling water flow rate and the stack inlet cooling water temperature with a given current step between the PI control and the state feedback control.

15 (a) is a graph showing a current shape.

15 (b) is a graph showing the temperatures of the catalyst and the cooling water in the absence of feed forward.

15 (c) is a graph showing the temperatures of the catalyst and the cooling water in the case of feed forward.

15 (d) is a graph showing the oxygen excess ratio after temperature compensation.

Claims (33)

A heat source including an air inlet, a cooling water inlet, and a cooling water outlet; An air source coupled to the air inlet of the heat source for flowing fluid therethrough and adapted to supply air to the heat source; An air supply control device adapted to regulate the air flow rate from the air source to the heat source based on a dynamic feedback temperature characteristic from the heat source; A cooling water supply source coupled to flow the fluid to the cooling water inlet of the heat source and configured to supply cooling water to the heat source; And A cooling water control device adapted to regulate a cooling water flow rate supplied to the heat source based on an estimated feed-forward heat source characteristic and to adjust a cooling water temperature supplied to the heat source based on the dynamic feedback temperature characteristic, ; / RTI > Wherein the cooling water outlet is coupled to the cooling water inlet through the heat source so as to flow, The heat source receives air through the air inlet, generates heat corresponding to the input of air, receives cooling water through the cooling water inlet, guides the input cooling water to the cooling water outlet, and receives a part of the generated heat Cooling water from the heat source, thereby removing part of the generated heat from the heat source when the cooling water is guided out of the heat source through the cooling water outlet. The method according to claim 1, Wherein the heat source is a fuel cell stack. 3. The method of claim 2, Wherein the fuel cell stack is a PEM (Polymer Electrolyte Membrane) fuel cell stack. 3. The method of claim 2, Further comprising a hydrogen tank coupled to the fuel cell stack so as to flow therethrough, wherein the hydrogen tank is adapted to supply hydrogen to the fuel cell stack. The method according to claim 1, Wherein the dynamic feedback temperature characteristic comprises information indicative of the cooling water temperature measured at the cooling water outlet of the heat source. The method according to claim 1, Wherein the estimated feedforward heat source characteristic comprises an estimate of the extreme heat of the heat source in a load profile. The method according to claim 6, Further comprising a feed forward controller adapted to regulate the cooling water flow rate based on the load profile and the interpolated map data. The method according to claim 1, Wherein the cooling water control device comprises at least one controller selected from the group of controllers consisting of a proportional-integral (PI) controller and a state feedback controller. The method according to claim 1, A cooling water reservoir adapted to store cooling water to be guided to and through a heat source; A cooling water pump for pumping cooling water from the cooling water reservoir to the heat source, the cooling water flow rate being controlled by the cooling water control device; A cooling device adapted to cool the cooling water from the heat source and to provide cooled cooling water to the cooling water reservoir; And The amount of cooling water to be supplied to the cooling device from the heat source for cooling is controlled, and the amount of the cooling water is adjusted by a bypass valve based on dynamic temperature information about the heat source; Further comprising: an air and cooling water control device. A heat source including an air inlet, a cooling water inlet, and a cooling water outlet; An air source coupled to the air inlet of the heat source for flowing fluid therethrough and adapted to supply air to the heat source; An air supply control device adapted to regulate the air flow rate from the air source to the heat source based on dynamic feedback temperature characteristics from the heat source; And A cooling water supply source coupled to flow the fluid to the cooling water inlet of the heat source and configured to supply cooling water to the heat source; / RTI > The heat source receives air through the air inlet, generates heat corresponding to the input of air, receives cooling water through the cooling water inlet, guides the input cooling water to the cooling water outlet, and receives a part of the generated heat Cooling water from the heat source, thereby removing part of the generated heat from the heat source when the cooling water is guided out of the heat source through the cooling water outlet. 11. The method of claim 10, And a cooling water control device adapted to adjust a cooling water flow rate supplied to the heat source based on the estimated feed-forward heat source characteristics. 12. The method of claim 11, Wherein the estimated feed-forward heat source characteristic comprises an over-heat estimate of a heat source in a load configuration. 13. The method of claim 12, Further comprising a feed forward controller adapted to regulate the cooling water flow rate based on the load profile and the interpolated map data. 11. The method of claim 10, Wherein the dynamic feedback temperature characteristic comprises information indicative of the cooling water temperature measured at the cooling water outlet of the heat source. 11. The method of claim 10, And a cooling water control device adapted to adjust a cooling water temperature supplied to the heat source based on the dynamic feedback temperature characteristic. 11. The method of claim 10, Wherein the heat source is a fuel cell stack. 17. The method of claim 16, Wherein the fuel cell stack is a PEM (Polymer Electrolyte Membrane) fuel cell stack. 17. The method of claim 16, Further comprising a hydrogen tank coupled to the fuel cell stack so as to flow therethrough, wherein the hydrogen tank is adapted to supply hydrogen to the fuel cell stack. 11. The method of claim 10, A cooling water reservoir adapted to store cooling water to be guided to and through a heat source; A cooling water pump for pumping cooling water from the cooling water reservoir to the heat source, the cooling water flow rate being controlled by the cooling water control device; A cooling device adapted to cool the cooling water from the heat source and to provide cooled cooling water to the cooling water reservoir; And The amount of cooling water to be supplied to the cooling device from the heat source for cooling is controlled, and the amount of the cooling water is adjusted by a bypass valve based on dynamic temperature information about the heat source; Further comprising: an air and cooling water control device. A heat source including an air inlet, a cooling water inlet, and a cooling water outlet; An air source coupled to the air inlet of the heat source for flowing fluid therethrough and adapted to supply air to the heat source; A cooling water supply source coupled to flow the fluid to the cooling water inlet of the heat source and configured to supply cooling water to the heat source; And A cooling water control device adapted to regulate a cooling water flow rate supplied to the heat source based on an estimated feed-forward heat source characteristic; , ≪ / RTI & The heat source receives air through the air inlet, generates heat corresponding to the input of air, receives cooling water through the cooling water inlet, guides the input cooling water to the cooling water outlet, and receives a part of the generated heat Cooling water to thereby remove part of the generated heat from the heat source when the cooling water is guided out of the heat source through the cooling water outlet, Wherein the estimated feed-forward heat source characteristic comprises an over-heat estimate of a heat source in a load configuration. delete 21. The method of claim 20, Further comprising a feed forward controller adapted to regulate the cooling water flow rate based on the load profile and the interpolated map data. A heat source including an air inlet, a cooling water inlet, and a cooling water outlet; An air source coupled to the air inlet of the heat source for flowing fluid therethrough and adapted to supply air to the heat source; A cooling water supply source coupled to flow the fluid to the cooling water inlet of the heat source and configured to supply cooling water to the heat source; And A cooling water control device adapted to regulate a cooling water flow rate supplied to the heat source based on an estimated feed-forward heat source characteristic; , ≪ / RTI & The heat source receives air through the air inlet, generates heat corresponding to the input of air, receives cooling water through the cooling water inlet, guides the input cooling water to the cooling water outlet, and receives a part of the generated heat Cooling water to thereby remove part of the generated heat from the heat source when the cooling water is guided out of the heat source through the cooling water outlet, Wherein the cooling water control device controls the temperature of the cooling water supplied to the heat source based on the dynamic feedback temperature characteristic of the heat source. 24. The method according to claim 20 or 23, Wherein the heat source is a fuel cell stack. 25. The method of claim 24, Wherein the fuel cell stack is a PEM (Polymer Electrolyte Membrane) fuel cell stack. 25. The method of claim 24, Further comprising a hydrogen tank coupled to the fuel cell stack so as to flow therethrough, wherein the hydrogen tank is adapted to supply hydrogen to the fuel cell stack. A heat source including an air inlet, a cooling water inlet, and a cooling water outlet; An air source coupled to the air inlet of the heat source for flowing fluid therethrough and adapted to supply air to the heat source; A cooling water supply source coupled to flow the fluid to the cooling water inlet of the heat source and configured to supply cooling water to the heat source; And A cooling water control device adapted to regulate a cooling water flow rate supplied to the heat source based on an estimated feed-forward heat source characteristic; , ≪ / RTI & The heat source receives air through the air inlet, generates heat corresponding to the input of air, receives cooling water through the cooling water inlet, guides the input cooling water to the cooling water outlet, and receives a part of the generated heat Cooling water to thereby remove part of the generated heat from the heat source when the cooling water is guided out of the heat source through the cooling water outlet, A cooling water reservoir adapted to store cooling water to be guided to and through a heat source; A cooling water pump for pumping cooling water from the cooling water reservoir to the heat source, the cooling water flow rate being controlled by the cooling water control device; A cooling device adapted to cool the cooling water from the heat source and to provide cooled cooling water to the cooling water reservoir; And The amount of cooling water to be supplied to the cooling device from the heat source for cooling is controlled, and the amount of the cooling water is adjusted by a bypass valve based on dynamic temperature information about the heat source; Further comprising: an air and cooling water control device. A heat source including an air inlet, a cooling water inlet, and a cooling water outlet; An air source coupled to the air inlet of the heat source for flowing fluid therethrough and adapted to supply air to the heat source; A cooling water supply source coupled to flow the fluid to the cooling water inlet of the heat source and configured to supply cooling water to the heat source; And A cooling water control device adapted to regulate a cooling water temperature supplied to the heat source based on a dynamic feedback temperature characteristic; , ≪ / RTI & The heat source receives air through the air inlet, generates heat corresponding to the input of air, receives cooling water through the cooling water inlet, guides the input cooling water to the cooling water outlet, and receives a part of the generated heat Cooling water from the heat source, thereby removing part of the generated heat from the heat source when the cooling water is guided out of the heat source through the cooling water outlet. 29. The method of claim 28, Wherein the dynamic feedback temperature characteristic comprises information indicative of the cooling water temperature measured at the cooling water outlet of the heat source. 29. The method of claim 28, Wherein the heat source is a fuel cell stack. 31. The method of claim 30, Wherein the fuel cell stack is a PEM (Polymer Electrolyte Membrane) fuel cell stack. 31. The method of claim 30, Further comprising a hydrogen tank coupled to the fuel cell stack so as to flow therethrough, wherein the hydrogen tank is adapted to supply hydrogen to the fuel cell stack. 29. The method of claim 28, A cooling water reservoir adapted to store cooling water to be guided to and through a heat source; A cooling water pump for pumping cooling water from the cooling water reservoir to the heat source, the cooling water flow rate being controlled by the cooling water control device; A cooling device adapted to cool the cooling water from the heat source and to provide cooled cooling water to the cooling water reservoir; And The amount of cooling water to be supplied to the cooling device from the heat source for cooling is controlled, and the amount of the cooling water is adjusted by a bypass valve based on dynamic temperature information about the heat source; Further comprising: an air and cooling water control device.

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