KR102086352B1 - Hybrid power system performing power distribution between fuel cell and battery - Google Patents

Abstract

Provided is a hybrid power system performing power distribution between fuel cells and batteries, including a controller which analyzes characteristics according to requirements of a fuel cell, a battery, and an external load to determine a load sharing ratio between the fuel cell and the battery based on at least one of a mechanical state control method and a purge control method. According to the present invention, the fuel cell output can be kept constant even if the external load fluctuates in the hybrid power system.

Description

HYBRID POWER SYSTEM PERFORMING POWER DISTRIBUTION BETWEEN FUEL CELL AND BATTERY}

The present invention relates to a hybrid power system that performs power distribution between fuel cell and battery. More particularly, the present invention relates to a technique for optimally distributing power between a fuel cell and a battery in a fuel cell-battery hybrid system for home / building.

A fuel cell is a device that generates electricity by an electrochemical reaction. Hydrogen ions (H +, protons) and electrons (e-, electrons) are dispersed by a platinum catalyst in which hydrogen (H ₂ ) supplied to the anode is dispersed on the electrode surface. It is characterized by being separated by). On the other hand, in the cathode, hydrogen ions moved through the electrolyte and electrons moved through the external load react with oxygen supplied to the cathode to generate water. Therefore, the fuel cell is an energy conversion device that generates electricity by the external flow of electrons in this process. Polymer Electrolyte Membrane Fuel Cell (PEMFC) is suitable for building and backup power supply because it has higher current density and output density, shorter start-up time and faster response to load changes than other types of fuel cells. . These fuel cells can achieve 2-3 times higher efficiency than the combustion method used in existing internal combustion engines, and are eco-friendly energy sources that can minimize the generation of environmental pollutants, and are commercialized in various fields through continuous research and development. It is becoming.

The fuel cell-battery hybrid system is a new concept of stand-alone renewable energy power supply that connects fuel cells and batteries in parallel to supply the required power according to demand. A fuel cell-battery hybrid system is composed of a fuel cell, a battery, a DC / DC converter, and a controller. A fuel cell may be used as a main energy source and a battery as an auxiliary energy source.

In such a system, the fuel cell power is operated at low power during low load operation while the surplus power is charged in the battery. On the other hand, during high load operation, the system outputs the maximum power within a range that satisfies the state of charge (SOC) by changing the power of the battery to the discharge mode at the same time as the fuel cell operation. Therefore, the fuel cell-battery hybrid system can stably operate the output of the fuel cell, thereby improving the life of the fuel cell. In addition, there is an advantage that the hydrogen fuel consumption can be reduced by maximizing the power of the battery by using the power charged in the battery during the high load operation while charging the battery produced in the low load operation. In addition, by supplying power through the discharge of the battery during high load operation, it is possible to downsize the fuel cell capacity compared to the fuel cell system of the same capacity has the advantage of reducing the system installation cost.

However, a typical fuel cell-battery hybrid system does not reflect external load fluctuations, fuel cell output, and battery charge rate in real time, and uses a simple method of using battery power only when a predetermined value or more is required. Therefore, since the fuel cell is responsible for most of the power demand (load), the fuel (hydrogen) consumption is increased, which leads to an increase in operating costs. On the other hand, if the required load condition in which the battery intervenes is set low, the fuel (hydrogen) consumption of the fuel cell is reduced, but on the contrary, the battery discharge occurs a lot, and as the time passes, the battery charge rate decreases and the battery is over discharged. This can result in a shorter use time.

Therefore, in the fuel cell hybrid system for home / building, there is a need for a technology that maintains a stable fuel cell output and a constant battery charge rate while providing power required by load fluctuation by optimally controlling the load sharing ratios of fuel cells and batteries in real time.

The present invention has been made to solve the above problems, and an object thereof is to provide a fuel cell hybrid system that maintains a constant fuel cell output even when an external load is changed in a fuel cell-battery hybrid system.

In addition, an object of the present invention is to provide a technique for optimally distributing power of a fuel cell and a battery in real time so that the fuel cell output is maintained at a constant rate and the battery is equal to or higher than a constant charging rate even when the external load is changed.

In order to achieve the above object, in one aspect, by analyzing the characteristics according to the requirements of the fuel cell, battery and external load to determine the load sharing ratio of the fuel cell and the battery at least one of a mechanical state control method and a purge control method Provided is a hybrid power system for performing power distribution between a fuel cell and a battery, the controller including a controller to determine based on the determination. In the hybrid power system, the fuel cell output may be kept constant even when the external load is changed.

In one aspect of the invention, the fuel cell may be at least one of a fuel cell, solar light, wind power. In this regard, the hybrid power system includes at least one of a fuel cell battery, a solar battery, a wind battery, a fuel cell solar battery, a fuel cell wind power battery, and a fuel cell solar power wind battery. Can be done.

As an aspect of the present invention, the controller may determine the load sharing ratio using an algorithm implemented by mixing the machine state control method and the fuzzy control method. In this regard, the load sharing ratio may satisfy the maximum load condition and the minimum load condition range that the fuel cell can output, and may satisfy the maximum charge rate and the minimum charge rate range of the battery.

As an aspect of the present invention, the method may further include a DC-DC converter disposed between the fuel cell and the external load. In this regard, the controller calculates an optimal fuel cell load according to a load change with current generated from the fuel cell, and outputs a fuel cell current based on the optimal fuel cell load. Can be controlled.

In one aspect of the invention, the controller is a first control unit for optimizing the load sharing ratio between the fuel cell and the battery using the machine state control method, the load between the fuel cell and the battery using the purge control method And a second controller for optimizing the sharing ratio, and a third controller for optimizing the load sharing ratio between the fuel cell and the battery using the machine state control method and the purge control method.

As an aspect of the present invention, the first control unit, the second control unit and the third control unit may each independently control the load sharing ratio.

In one aspect of the present invention, the first control unit, the second control unit and the third control unit input a state of charge (SOC), a current fuel cell current, and a demand load, and use the fuel of a next step. The battery current is controlled as an output.

In one aspect of the present invention, the controller compares the reference output value of the fuel cell current between the kth step and the k + 1th step, and if the output change amount is less than or equal to the threshold value I _small , the reference output value at the kth step. You can use (I ^* _{fc, k} ). On the other hand, if the output change amount is above the threshold value I _small . The stress of the fuel cell is reduced by smoothing the output change amount by a time constant τ using a time delay function.

As an aspect of the present invention, the fuel cell current is output to the external load according to the optimal fuel cell load between the fuel cell and the battery by using the DC-DC converter, and thus the power between the fuel cell and the battery is increased. Distribution can be performed.

As described above, according to the exemplary embodiment of the present invention, the fuel cell output may be kept constant even if the required load is changed in the fuel cell-battery hybrid system for home / building.

In addition, according to an embodiment of the present invention, even if the demand load is changed, it is possible to optimally control the load load of the fuel cell and the battery in real time such that the fuel cell output is kept constant and the battery is equal to or greater than a certain charge rate.

In addition, according to an embodiment of the present invention, it is possible to stably operate the fuel cell-battery hybrid system by optimally controlling the loads of the fuel cell and the battery in real time.

In addition, according to an embodiment of the present invention, by optimally controlling the load of the fuel cell and the battery in real time, the fuel (hydrogen) consumption of the fuel cell is minimized while maintaining a constant battery charge rate and extending the life of the system It can be effective.

1 is an exemplary view showing a schematic configuration of an apparatus for optimizing load distribution between a fuel cell and a battery in a fuel cell-battery hybrid system.
2 is a control block diagram of a machine state control and a fuzzy control, in accordance with an embodiment of the invention.
3 illustrates a fuzzy control block diagram, in accordance with an embodiment of the present invention. That is, FIG. 3 is a fuzzy control block diagram used to control the load distribution of the hybrid system.
4 illustrates a machine state control block diagram, in accordance with an embodiment of the present invention.
FIG. 5 is a graph comparing operation results of a hybrid system with respect to a control method of machine state control and the present invention (machine state control and fuzzy control) under actual external load conditions according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, the embodiments described below are suitable embodiments for understanding the hybrid power system 1000 of the present invention. However, the present invention is not limited to the technical features of the present invention by the embodiments to be applied or described in the embodiments described below, various modifications are possible in the technical scope of the present invention.

Meanwhile, the present invention relates to a technology for optimally distributing power between a fuel cell and a battery in a fuel cell-battery hybrid system for home / building. More specifically, in the fuel cell-battery hybrid system for home / building, a technique for optimally distributing the power supplied by the fuel cell and the battery by monitoring the fuel cell output and the battery charge rate to the power demand (load) in real time will be. Accordingly, the present invention relates to a technique for maintaining a battery at a constant charge rate or more while maintaining a constant fuel cell output even when an external load is changed.

1 is an exemplary view showing a schematic configuration of an apparatus for optimizing load distribution between a fuel cell and a battery in a fuel cell-battery hybrid system.

As shown in FIG. 1, the fuel cell-battery hybrid system 1000 according to the present embodiment charges the fuel cell 100 (A), which is the main source of power, and the power produced by the fuel cell at low load, and then loads the high load. The battery 200, B, which supplies power during operation, the controller 300, C, which optimally distributes the load between the fuel cell and the battery, and the actual load distribution between the fuel cell and the battery calculated by the controller. DC / DC converter 400, D.

Specifically, the controller 300 analyzes the characteristics according to the requirements of the external load to determine the load sharing ratio of the fuel cell 100 and the battery 200 based on at least one of a mechanical state control method and a purge control method. .

Meanwhile, the hybrid power system 1000 according to the present invention is not limited to the combination of the fuel cell 100 and the battery 200 as shown in FIG. 1. The fuel cell 100 according to the present invention may include at least one of a (hydrogen) fuel cell, a solar cell, and a wind cell. Accordingly, the hybrid power system 1000 according to the present invention is a fuel cell-battery, solar-battery, wind-battery, fuel cell-solar-battery, fuel cell-wind power-battery, fuel cell-solar-wind power. -At least one of the batteries.

The controller 300 may determine a load sharing ratio using an algorithm implemented by mixing a machine state control method and a fuzzy control method. In this case, the load sharing ratio may satisfy the maximum load condition and the minimum load condition range that the fuel cell can output, and may satisfy the maximum charge rate and the minimum charge rate range of the battery.

Meanwhile, the DC / DC converter 400 is disposed between the fuel cell 100 and an external load. At this time, the controller 300 calculates an optimal fuel cell load according to the load variation with the current generated from the fuel cell 100, and outputs a fuel cell current based on the optimum fuel cell load. 400 can be controlled.

The controller 300 may include a first controller, a second controller, and a third controller using different control methods. In this case, the first controller, the second controller, and the third controller may correspond to a plurality of controllers that perform logically different functions in addition to the plurality of controllers that are physically separated.

On the other hand, the first control unit may optimize the load sharing ratio between the fuel cell 100 and the battery 200 by using a mechanical state control method. In addition, the second controller may optimize the load sharing ratio between the fuel cell 100 and the battery 200 by using a purge control method. On the other hand, the third controller may optimize the load sharing ratio between the fuel cell 100 and the battery 200 by using the machine state control method and the purge control method.

On the other hand, the first control unit, the second control unit and the third control unit according to the present invention may be configured to independently control the load sharing ratio. In detail, the first control unit, the second control unit, and the third control unit may input a state of charge (SOC), a fuel cell current of a current stage, a required load, and control the fuel cell current of a next stage as an output. Can be.

On the other hand, the controller 300 according to the present invention can reduce the stress of the fuel cell by smoothing the output change amount of the fuel cell current. In this regard, the controller 300 determines that the output variation is greater than or equal to the threshold I _small . The stress of the fuel cell can be reduced by smoothing the output change amount by the time constant τ using a time delay function. On the other hand, the controller 300 compares the reference output value of the fuel cell current between the kth step and the k + 1th step, and if the output change amount is less than or equal to the threshold value I _small , the reference output value I ^* at the kth step. _{fc, k} ) can be used.

Meanwhile, the hybrid system according to the present invention may output the fuel cell current to the external load according to the optimal fuel cell load between the fuel cell 100 and the battery 200 using the DC-DC converter 400. As such, the DC-DC converter 400 outputs the fuel cell current to the external load according to the optimal fuel cell load between the fuel cell 100 and the battery 200, thereby providing power between the fuel cell 100 and the battery 200. Distribution can be performed.

2 illustrates a control block diagram of a machine state control and a purge control according to an embodiment of the present invention. That is, FIG. 2 is a flowchart illustrating an algorithm for optimally controlling the load distribution of the fuel cell-battery hybrid system of FIG. 1 in real time, and simultaneously uses machine state control and purge control.

Machine state control is a control method that monitors the state of the battery SOC and stops charging the battery when overcharging and increases the charging current during overdischarging to perform rapid charging. On the other hand, when the battery SOC is a constant section is a control method to perform a low-speed charging using the charging current of the intermediate value. In this regard, the battery charge state checking step (S110) of checking whether the battery charge state SOC is in a range between SOC _min and SOC _max is performed.

On the other hand, the purge control monitors not only the battery SOC state but also the current required power value, the fuel cell output current value, and the like to provide sufficient external power. In addition, purge control is a control method of adjusting the output of the fuel cell to maintain an appropriate battery SOC.

In this regard, the fuzzy logic controller may use the fuel cell current output value I ^* _fc . Specifically, the output current value difference comparing the difference of the output value of the fuel cell current (ΔI _fc = I ^* _{fc, k + 1} -I ^* _{fc, k} ) between the kth step and the k + 1th step with a specific value. The comparison step S120 may be performed. ΔI is a specific value I _small If greater than the output current limiting step (S121) for limiting the fuel cell output current is performed. On the other hand, ΔI is a specific value I _small If it is smaller than the output current value reuse step (S122) for reusing the output current value in the k-th step is performed.

In addition, an output current value comparison step S130 may be performed to determine whether the output current value I ^* _fc is between the maximum output value I _{fc and max} and the minimum output value I _{fc and min} . In this case, if the output current value (I ^* _fc ) is between the maximum output value (I _{fc , max} ) and the minimum output value (I _{fc , min} ) _, the fuzzy control can be continuously performed using the output current value (I ^* _fc ). have. On the other hand, if the output current value (I ^* _fc ) is above the maximum output value (I _{fc , max} ) or below the minimum output value (I _{fc , min} ) _{, the} output current value (I ^* _fc ) is limited to the maximum output value or the minimum output value, respectively. Purge control can be performed.

Therefore, the control method in which the machine state control method and the fuzzy control method according to the present invention have the following advantages. In this regard, when the SOC of the battery is in the charge / discharge boundary state, if only the machine state control is used, the battery is frequently charged and discharged, and thus the output variation of the fuel cell becomes severe. In order to solve this problem, according to the present invention, the fuzzy control may be used simultaneously with the machine state control method so that the output variation of the fuel cell is small.

3 illustrates a fuzzy control block diagram, in accordance with an embodiment of the present invention. That is, FIG. 3 is a fuzzy control block diagram used to control the load distribution of the hybrid system. Specifically, the upper figure shows the membership function of the purge controller and the lower figure shows the fuel cell reference output calculated by the fuzzy control logic. The input membership function includes the state of charge (SOC), the required load power, and the current fuel cell current value. The output membership function calculates the optimal fuel cell current value. By controlling the DC / DC converters 400 and D of FIG. 1 based on the calculated optimum fuel cell current value, a desired actual output value is output to the load.

The fuzzy inference rule base corresponds to the controller of the system and is based on truth table logic. The rule base is the set of rules associated with the fuzzy set, input variables, and output variables, which determine what to do in each case. Generally, one of the following forms depends on the number of inputs and outputs.

if <condition> then <execute>

if <condition 1 and condition 2> then <run>

if <condition 1 and condition 2 and condition 3> then <run>

In the present invention, there are three inputs and the output has one variable. Input variable 1 is battery SOC and has five conditions (very high, high, medium, low, very low), and input variable 2 is an external power requirement with eight conditions (very high, medium high, high, slightly High, medium, small, medium small, very small), input variable 3 is the current fuel cell output value and has five conditions (I1, I2, I3, I4, I5). These condition values are not determined but are changed by the designer's experience and experimentation. The output variable is the fuel cell output current in the next step and is determined according to the three input variable conditions. Accordingly, the number of inference equations is 5 * 8 * 5 = 200 and is displayed in three dimensions as shown in FIG. 3.

For example, out of 200 inferences,

Inference Formula 1:

if <SOC = Very small (VS), external power requirement = Very small (VS), current fuel cell output = small (I1)>, then I _{fc, ref} = small (I2)

(Description) If the SOC is very small, the external power demand is very small, and the current fuel cell output is small, the fuel cell output of the next step is to maintain the current output in order to charge the battery while preventing the sudden fuel cell output change. Small ”.

Reasoning 2:

if <SOC = small (S), external power requirement = medium high (ML), current fuel cell output = large (I4)>, then I _{fc, ref} = very high (I5)

(Explanation) Small SOC, medium external power demand, high current fuel cell output, increases fuel cell output one step from the current "large" to charge the battery while avoiding abrupt changes in fuel cell output. Very large ”.

According to an embodiment, the purge controller of FIG. 3 determines a membership function between 0.3 and 0.8 for a battery charge rate, a required load size between 300W and 1200W, and a fuel cell current size between 0A and 50A. On the other hand, the membership function determination can be tuned to an optimal value while driving the actual fuel cell-battery hybrid system.

Using this method, the output of the fuel cell is determined based on the SOC range, the required load power, and the current fuel cell output size. You can get it.

4 illustrates a machine state control block diagram, in accordance with an embodiment of the present invention. 4 is a machine state control block diagram used to control load distribution in a hybrid system. Referring to FIG. 4, three output values (high power, medium power, and low power) to be output from the fuel cell are calculated by receiving the current battery charge rate value. The range of battery charge rates can be determined by the operating environment of the fuel cell-battery hybrid system. For example, if the battery charge rate is between 40% -70% (40% <SOC <70%), the fuel cell outputs an optimal current. In addition, when the battery charge rate is less than 30% (SOC <30%), a high output value (High current) is output. In addition, when the battery charge rate is 70% or more (SOC> 70%), a low output value is output. On the other hand, if the battery charge rate is over 90% (SOC> 90%), the battery stops charging.

The control method used to control the load distribution of the hybrid system is as follows.

SOC _min <SOC <SOC _max

I _fc , _min <I ^* _fc <I _{fc, max}

if I ^* _fc > I _{fc, max} I ^* _fc = I _{fc , max}

if I ^* _fc <I _{fc , min} I ^* _fc = I _{fc , min}

In the above equation, I ^* _fc is the reference current value of the fuel cell to be controlled by the DC / DC converter, respectively _, and operates between I _{fc , max which is the} maximum output value of the fuel cell and I _{fc , min} which is the minimum output value to protect the fuel cell. At the same time, in order to prevent overcharging and overdischarging of the battery, the maximum charge rate of the battery is set to SOC _max and the minimum charge rate SOC _min , respectively, and the present invention is controlled to operate within these ranges.

Since the sudden increase and decrease of the load of the fuel cell has a bad effect on the fuel cell life, the present invention uses the following method of limiting the sudden change of the fuel cell in order to suppress the sudden change of the fuel cell output.

ΔI = I ^* _{fc, k + 1} -I ^* _{fc, k}

if | △ I | I _small I ^* _{fc, k + 1} = I ^* _{fc, k} + △ I / (τs + 1)

if | △ I | I _small I ^* _{fc, k + 1} = I ^* _{fc, k}

In the above formula,? I represents the difference between the newly calculated reference fuel cell current value and the current fuel cell current value, and the index k is the kth sampling time. The present invention compares the fuel cell reference output between the k + 1 step and the immediately preceding step k step so that the current amount of the fuel cell does not change when the output change amount is within I _small . On the other hand, if the reference output change is more than I _small, the time constant? As a result, the amount of change in fuel cell output is changed gently. As such, the amount of change in the fuel cell output is gently changed to reduce the stress of the fuel cell. At this time, the time constant τ and the output variation I _small are designed to fit the system. As the time constant increases, the time delay increases, so the reference output value is slowly approached. If the time constant is 0, the fuel cell output is instantaneously I ^* _{fc, k + 1} = I ^* _{fc, k} + ΔI.

FIG. 5 is a graph comparing operation results of a hybrid system with respect to a control method of machine state control and the present invention (machine state control and fuzzy control) under actual external load conditions according to an embodiment of the present invention. That is, Figure 5 shows an example of the experimental results of the operation of the hybrid system according to the external load change using the system of FIG. Referring to FIG. 5, when only the machine state control is used (A), the results of the system operation experiment show that the results match well with the actual required load output, but the output of the fuel cell is not stabilized and changes significantly according to the load variation. Appeared to be. However, in the case of using the method (machine control + fuzzy control) used in the present invention, the results of the system operation experiment (B) are in good agreement with the actual required load output, and at the same time, the fuel cell output is not significantly affected by the load fluctuation. It appeared to be stable without. That is, when only the machine state control is used under the same external load demand condition, both (A) and (B) when using the present invention can satisfy the external load condition. However, it can be seen that the fuel cell output is stable only when the method of the present invention is used, and as a result, it is possible to extend the life of the fuel cell by reducing the stress on the fuel cell. In addition, in the case of using the present invention, it was shown that the change in battery charge rate is small under the same external load condition, and from this result, the present invention can extend battery life by reducing the number and range of frequent charge / discharge of the battery.

In the above, the hybrid power system performing power distribution between the fuel cell and the battery according to the present invention has been described. That is, the present invention is a technology for optimally distributing the power between the fuel cell and the battery in a fuel cell-battery hybrid system for home / building, and optimally controlling the load sharing of the fuel cell and the battery in real time according to the load variation, thereby changing the fuel cell load variation. Minimize the charge rate and keep the battery's charge rate constant.

In the present invention, for the optimal power distribution between the fuel cell and the battery, the machine state control method, the fuzzy control method, and a hybrid control method combining the two advantages, and the power distribution through the DC / DC converter control. This method satisfies the maximum or minimum charge rate of the battery while satisfying the maximum load and the minimum load that the fuel cell can output even when the external load changes.

In addition, the present invention can improve the life of the fuel cell and the battery and at the same time reduce the fuel consumption as compared to the existing technology using the fuel cell load and the battery load only when a load equal to or greater than a preset value is required. In addition, the fuel cell capacity can be downsized as compared with the fuel cell system alone, thereby reducing the cost of installing and maintaining the system and operating the system stably.

The present invention is also applicable to fuel cell battery hybrid systems, solar battery hybrid systems, wind battery hybrid systems and fuel cell- photovoltaic- wind- battery hybrid systems.

And while the present invention has been shown and described with respect to specific embodiments, it is understood that the present invention may be variously modified and changed without departing from the spirit or the scope of the present invention provided by the following claims. It will be apparent to those skilled in the art that they can easily know.

1000: hybrid power system
100: fuel cell
200: battery
300: controller
400: DC-DC converter
S120: Battery charge check step
S120: difference step of output current value comparison
S121: Output Current Limit Step
S122 ： Reuse of Output Current Value
S130: output current value comparison step

Claims (10)

A hybrid power system that performs power distribution between a fuel cell and a battery,
Fuel cell;
battery; And
A controller for analyzing a characteristic according to a requirement of an external load to determine a load sharing ratio of the fuel cell and the battery based on at least one of a mechanical state control method and a purge control method,
The controller,
A first control unit optimizing a load sharing ratio between the fuel cell and the battery using the machine state control method;
A second controller which optimizes a load sharing ratio between the fuel cell and the battery using a gas purge control method; And
And a third controller for optimizing a load sharing ratio between the fuel cell and the battery using the machine state control method and the purge control method. The method of claim 1,
The fuel cell is at least one of a fuel cell, a solar cell, a wind cell,
The hybrid power system comprises at least one of a fuel cell-battery, a solar-battery, a wind-battery, a fuel cell-solar-battery, a fuel cell-wind-battery, and a fuel cell-solar-wind-battery. , Hybrid power system. The method of claim 1,
The controller,
The load sharing ratio is determined using an algorithm implemented by mixing the machine state control method and the fuzzy control method.
And the load sharing ratio satisfies the maximum load condition and the minimum load condition range that the fuel cell can output, and satisfies the maximum charge rate and the minimum charge rate range of the battery. The method of claim 1,
Further comprising a DC-DC converter disposed between the fuel cell and the external load,
The controller calculates an optimal fuel cell load according to a load change with the current generated in the fuel cell, and controls the DC-DC converter to output a fuel cell current based on the optimal fuel cell load. Hybrid power system. delete The method of claim 1,
The first control unit, the second control unit and the third control unit, characterized in that each independently control the load sharing ratio, hybrid power system. The method of claim 6,
The first controller, the second controller, and the third controller are configured to input a state of charge (SOC), a fuel cell current of a current stage, and a demand load, and control the fuel cell current of a next stage as an output. Characterized in that, the hybrid power system. The method of claim 7, wherein
The controller,
And a proportional integral control is used to constantly converge the reference output value of the fuel cell current and the air charge measured in the fuel cell. The method of claim 7, wherein
The controller,
Comparing the reference output value of the fuel cell current between the kth step and the k + 1th step, if the output change amount is less than or equal to the threshold value I _small , the reference output value I ^* _{fc, k} at the kth step is used. ,
If the output change amount is greater than or equal to a threshold value I _small . And the stress of the fuel cell is reduced by smoothing the output change amount by a time constant τ using a time delay function. The method of claim 4, wherein
And using the DC-DC converter to output the fuel cell current to the external load according to the optimal fuel cell load between the fuel cell and the battery to perform power distribution between the fuel cell and the battery. , Hybrid power system.

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