CN115966732B - Fuel cell power system and output power control method thereof - Google Patents
Fuel cell power system and output power control method thereof Download PDFInfo
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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Abstract
The invention relates to a fuel cell power system and an output power control method thereof, wherein the fuel cell power system comprises a fuel cell stack unit, a cell management unit, an energy storage unit and an air compressor, wherein an outlet of the air compressor is communicated with an air inlet of the fuel cell stack unit and is used for providing high-pressure air for the fuel cell stack unit, the cell management unit is respectively and electrically connected with the energy storage unit and the fuel cell stack unit and is used for controlling operation parameters of the energy storage unit and the fuel cell stack unit, the energy storage unit is electrically connected with the air compressor and is used for providing electric energy for the air compressor. Compared with the prior art, the electric energy of the air compressor is provided by the energy storage unit, the consumption of the output power of the fuel cell stack unit can be reduced when the system is loaded, so that the response speed of the fuel cell stack to the external output power of the system is improved, and the kinetic energy is recovered to the energy storage unit when the system is in load reduction, so that the air supply flow is reduced rapidly, the dynamic response speed of the air compressor is improved effectively, and the response speed of the output power of the system is improved.
Description
Technical Field
The invention relates to the technical field of fuel cells, in particular to a fuel cell power system and an output power control method thereof.
Background
In recent years, as environmental pollution becomes more serious, environmental pollution prevention, environmental protection and ecological balance maintenance have become requirements for sustainable development of society. The fuel cell is a high-efficiency power generation device which directly converts chemical energy in fuel (such as hydrogen, natural gas and the like) and oxidant into electric energy in an electrochemical reaction mode without a combustion process, and the main product is water, and basically no harmful gas is discharged, so the fuel cell has the characteristics of no pollution, zero emission and high energy conversion efficiency. Because conventional petroleum energy sources have not been able to meet the power demands of the current automotive industry, fuel cells with superior performance are widely regarded as the best choice for future electric car energy schemes.
Typical fuel cell power system architectures include a fuel cell, an output control circuit, and a reactive environment supply assembly for the fuel cell, which generally have a low response speed, and under dynamic conditions, the reactive environment of the fuel cell requires millisecond response times to reach an ideal state, which is difficult to achieve in the prior art.
The air compressor is a main component in the reaction environment supply assembly and is used for supplying oxygen to the cathode of the fuel cell, the air compressor is driven by the motor and the expander together, and the power density and the efficiency of the fuel cell can be improved by pressurizing cathode gas, so that the size of a power system of the fuel cell is reduced. However, the parasitic power consumption of the air compressor is large and accounts for about 80% of the auxiliary functions of the fuel cell, so that the stoichiometric ratio in the fuel cell engine is directly influenced, and the dynamic response speed of the fuel cell power system is further influenced.
Disclosure of Invention
The present invention is directed to a fuel cell power system and a method for controlling the output power thereof, which overcome the above-mentioned drawbacks of the prior art.
The aim of the invention can be achieved by the following technical scheme:
The utility model provides a fuel cell power system, includes fuel cell stack unit, battery management unit, energy storage unit and air compressor machine, the export of air compressor machine with the air inlet intercommunication of fuel cell stack unit is used for providing high-pressure air to fuel cell stack unit, battery management unit respectively with energy storage unit the fuel cell stack unit electricity is connected, is used for control the operating parameter of energy storage unit the fuel cell stack unit, energy storage unit with the air compressor machine electricity is connected, the energy storage unit is used for providing the electric energy for the air compressor machine.
In one embodiment, the fuel cell power system further includes an output power monitoring unit electrically connected to the battery management unit and configured to transmit an output power signal to the battery management unit.
In one embodiment, the output power monitoring unit is further electrically connected to the air compressor and is configured to transmit an output power signal to the air compressor.
In one embodiment, the fuel cell power system further includes a fuel unidirectional DC/DC converter, and the fuel cell stack unit is electrically connected to the battery management unit through the fuel unidirectional DC/DC converter, for supplying direct current power to the battery management unit.
In one embodiment, the fuel cell power system further includes an external load electrically connected to the battery management unit, the battery management unit further configured to provide electrical power to the external load.
In one embodiment, the energy storage unit comprises an energy storage battery and an energy storage unidirectional DC/DC converter, and the energy storage battery is electrically connected with the battery management unit through the energy storage unidirectional DC/DC converter.
In one embodiment, the energy storage unit further comprises a motor controller with a kinetic energy recovery function, and the energy storage battery is electrically connected with the air compressor through the motor controller.
The output power control method of the fuel cell power system is suitable for the fuel cell power system and comprises the following steps:
Acquiring target output power of a fuel cell power system by adopting a battery management unit;
The battery management unit determines an air compressor control signal according to the target output power, adjusts operation parameters of the air compressor based on the air compressor control signal, and enables the sum of the output power of the fuel cell stack unit and the output power of the energy storage unit to be actual output power so that the actual output power tends to the target output power;
Wherein, the control signal of the air compressor accords with a preset output function with the target output power;
The control method further includes:
Acquiring deviation information of a first variable and a second variable output by the fuel cell power system and a preset characteristic curve by adopting the battery management unit;
And the electric loop of the fuel cell power system is regulated according to the deviation information, so that the first class variable and the second class variable tend to be on a preset characteristic curve.
According to the output power control method of the fuel cell power system, under the condition that the target output power is confirmed, the preset output function is utilized to regulate and control the air compressor control signal, the actual power output requirement can be met according to the output function under different application scenes, the application range is wide, the control implementation effect is good, and the energy storage unit and the fuel cell stack unit jointly output electric energy to the outside, so that the system has the advantages of stable operation voltage, wide operation fault tolerance, energy waste reduction and the like.
In one embodiment, the type of variable is an output current or an output current density of the fuel cell power system, or a variable calculated therefrom, the output current of the fuel cell power system being determined according to the output current of the fuel cell unit and the output current of the energy storage unit, the output current density of the fuel cell power system being determined according to the output current density of the fuel cell unit and the output current density of the energy storage unit;
The second-class variable is output voltage, output power or internal resistance compensation output voltage of the fuel cell power system or a variable calculated by the second-class variable, the output voltage of the fuel cell power system is determined according to the output voltage of the fuel cell unit and the output voltage of the energy storage unit, the output power of the fuel cell power system is determined according to the output power of the fuel cell unit and the output power of the energy storage unit, and the internal resistance compensation output voltage of the fuel cell power system is determined according to the internal resistance compensation output voltage of the fuel cell unit and the internal resistance compensation output voltage of the energy storage unit.
In one embodiment, the air compressor control signal is an air compressor torque, rotational speed, current, power, or PWM duty cycle, or a variable calculated therefrom.
Compared with the prior art, the fuel cell power system has the advantages that the fuel cell stack unit is used for generating electrochemical reaction and generating electric energy, the air compressor is used for providing high-pressure air for the fuel cell stack unit, the battery management unit is used for controlling the energy storage unit and the operation parameters of the fuel cell stack unit, the battery management unit is connected with the fuel cell stack unit and used for outputting the electric energy generated by the fuel cell stack unit to an external load, the battery management unit and the energy storage unit can be used for conveying the surplus electric energy generated by the fuel cell stack unit to the energy storage unit, the energy storage unit can also be used for releasing the stored electric energy to the battery management unit, and meanwhile, the energy storage unit is electrically connected with the air compressor and used for providing electric energy for the air compressor to operate. Therefore, when the battery management unit monitors the outputtable power of the fuel cell stack unit (the required power of the external load), the energy storage unit is required to release the stored electric energy to the battery management unit, and when the battery management unit monitors the outputtable power of the fuel cell stack unit (the required power of the external load), the fuel cell stack unit provides all the required power and the redundant electric energy is transmitted to the energy storage unit for storage. In the process of chemical reaction of the fuel cell stack unit and generation of electric energy, the electric energy of the air compressor is provided by the energy storage unit, so that the consumption of the output power of the fuel cell stack unit can be reduced when the system is loaded, the response speed of the fuel cell stack to the external output power of the system is improved, and the kinetic energy is recovered to the energy storage unit when the system is in load reduction, so that the air supply flow is reduced rapidly, the dynamic response speed of the air compressor is improved effectively, and the response speed of the output power of the system is improved.
Drawings
FIG. 1 is a schematic diagram of a fuel cell power system according to an embodiment;
FIG. 2 is a schematic diagram of a method of controlling output power of a fuel cell power system according to an embodiment;
FIG. 3 is a schematic diagram of the condition curves and characteristic curves provided in one embodiment.
Reference numerals: 100. a fuel cell power system; 10. a fuel cell stack unit; 20. a battery management unit; 30. an energy storage unit; 40. an air compressor; 50. an output power monitoring unit; 60. an external load.
Detailed Description
The invention will now be described in detail with reference to the drawings and specific examples. The present embodiment is implemented on the premise of the technical scheme of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following examples.
As shown in fig. 1, in an embodiment, a fuel cell power system 100 is provided, including a fuel cell stack unit 10, a battery management unit 20, an energy storage unit 30 and an air compressor 40, wherein an outlet of the air compressor 40 is communicated with an air inlet of the fuel cell stack unit 10, and is used for providing high-pressure air to the fuel cell stack unit 10, the battery management unit 20 is respectively electrically connected with the energy storage unit 30 and the fuel cell stack unit 10, and is used for controlling operation parameters of the energy storage unit 30 and the fuel cell stack unit 10, the energy storage unit 30 is electrically connected with the air compressor 40, and the energy storage unit 30 is used for providing electric energy for the air compressor 40.
In the fuel cell power system 100, the fuel cell stack unit 10 is configured to perform electrochemical reaction and generate electric energy, the air compressor 40 is configured to provide high-pressure air to the fuel cell stack unit 10, the battery management unit 20 is configured to control the energy storage unit 30 and the operation parameters of the fuel cell stack unit 10, the battery management unit 20 is connected to the fuel cell stack unit 10 and is configured to output the electric energy generated by the fuel cell stack unit 10 to the external load 60, the battery management unit 20 is connected to the energy storage unit 30, the battery management unit 20 may supply the surplus electric energy generated by the fuel cell stack unit 10 to the energy storage unit 30, and the energy storage unit 30 may also release the stored electric energy to the battery management unit 20, and meanwhile, the energy storage unit 30 is electrically connected to the air compressor 40 and is configured to provide the electric energy to the air compressor 40 for operation. Therefore, when the battery management unit 20 monitors the outputtable power of the fuel cell stack unit 10 < the required power of the external load 60, the energy storage unit 30 is required to discharge the stored electric energy to the battery management unit 20, and when the battery management unit 20 monitors the outputtable power of the fuel cell stack unit 10 > the required power of the external load 60, the fuel cell stack unit 10 provides the total required power and supplies the surplus electric energy to the energy storage unit 30 for storage. In the process of chemical reaction of the fuel cell stack unit 10 and electric energy generation, the electric energy of the air compressor 40 is provided by the energy storage unit 30, so that the consumption of the output power of the fuel cell stack unit 10 can be reduced when the system is loaded, the response speed of the electric stack to the external output power of the system is improved, and the kinetic energy of the air compressor 40 is recovered to the energy storage unit 30 when the system is in load reduction, so that the air supply flow is reduced rapidly, the dynamic response speed of the air compressor 40 is improved effectively, and the response speed of the output power of the system is improved.
Specifically, as shown in fig. 1, in an embodiment, the fuel cell power system 100 further includes an output power monitoring unit 50, and the output power monitoring unit 50 is electrically connected to the battery management unit 20 and is configured to transmit an output power signal to the battery management unit 20.
Further, as shown in fig. 1, in an embodiment, the output power monitoring unit 50 is further electrically connected to the air compressor 40 and is used for transmitting an output power signal to the air compressor 40. The air compressor 40 can adjust the air supply pressure and air supply amount of the air compressor 40 to the fuel cell stack unit 10 according to the change of the output power signal, so as to adjust the output power of the fuel cell stack unit 10, and the output power monitoring unit 50 is connected with the air compressor 40 to realize a feedback mechanism of the air supply pressure, the air supply amount and the output power, which is beneficial to improving the response speed of the air compressor 40.
In this embodiment, the output power monitoring unit 50 includes an output current sensor, an output voltage sensor and a controller, one end of the output current sensor is connected to the output end of the fuel cell stack unit 10 for testing the output current of the fuel cell stack unit 10, the other end of the output current sensor is connected to the controller, one end of the output voltage sensor is connected to the output end of the fuel cell stack unit 10 for testing the output voltage of the fuel cell stack unit 10, the other end of the output voltage sensor is connected to the controller, the controller is connected to the battery management unit 20 and the air compressor 40, respectively, and the controller is used for acquiring the output power of the fuel cell stack unit 10 according to the output voltage and the output current and transmitting the output power signals to the battery management unit 20 and the air compressor 40, respectively. The battery management unit 20 can further regulate the operation parameters of the energy storage unit 30 and the fuel cell stack unit 10 according to the magnitude between the output power of the fuel cell stack unit 10 and the required power of the external load 60. When the output power of the fuel cell stack unit 10 < the required power of the external load 60, the battery management unit 20 controls the energy storage unit 30 and the fuel cell stack unit 10 to simultaneously discharge electric energy, and when the output power of the fuel cell stack unit 10 > the required power of the external load 60, the battery management unit 20 controls the fuel cell stack unit 10 to discharge electric energy and to supply surplus electric energy to the energy storage unit 30.
The operation parameters of the fuel cell stack unit 10 include the target current output by the fuel cell stack unit 10, the target voltage output by the fuel cell stack unit 10, the target power output by the fuel cell stack unit 10, the equivalent output impedance value, the internal resistance compensation output voltage, the internal resistance compensation output power, the thermal power output by the fuel cell stack unit 10, the switching duty ratio of the control circuit electronic devices, or other control circuit state parameters capable of changing the chemical power supply output current, voltage or electric power.
Specifically, in one embodiment, the fuel cell power system 100 further includes a fuel unidirectional DC/DC converter through which the fuel cell stack unit 10 is electrically connected to the battery management unit 20 for supplying direct current electric power to the battery management unit 20.
The unidirectional fuel DC/DC converter is used for converting direct current generated by the fuel cell stack unit 10 into high-voltage direct current and outputting the high-voltage direct current to the battery management unit 20, so that the voltage output by the fuel cell stack unit 10 can be adapted to the voltage of the battery management unit 20.
Specifically, as shown in fig. 1, in an embodiment, the fuel cell power system 100 further includes an external load 60, the external load 60 being electrically connected to the battery management unit 20, the battery management unit 20 further being configured to provide electrical power to the external load 60. The system adopts the battery management unit 20 to be directly connected with the external load 60, so as to conveniently regulate and control the output power of the fuel cell stack unit 10, adapt to the power required by the external load 60,
Specifically, in one embodiment, the energy storage unit 30 includes an energy storage battery and an energy storage unidirectional DC/DC converter, and the energy storage battery is electrically connected with the battery management unit 20 through the energy storage unidirectional DC/DC converter. The energy storage unidirectional DC/DC converter is used to convert the output voltage of the energy storage battery into high-voltage direct current and output the high-voltage direct current to the external load 60 through the battery management unit 20, so that the energy storage battery can assist the fuel cell stack unit 10 in outputting electric energy.
In one embodiment, the energy storage unit 30 further includes a motor controller with a kinetic energy recovery function, and the energy storage battery is electrically connected to the air compressor 40 through the motor controller. The motor controller is configured to convert the dc power of the energy storage battery into ac power and output the ac power to the air compressor 40, and the power flow direction of the motor controller may be bidirectional, so that the ac power of the air compressor 40 may be converted into dc power and stored in the energy storage battery.
In this particular embodiment, the energy storage battery comprises one or more of a lead acid battery, a lead carbon battery, a lithium ion battery, a flow battery, a sodium sulfur battery, and a supercapacitor. Preferably, the energy storage battery is a lithium titanate battery or an all-vanadium redox flow battery.
Specifically, in an embodiment, the air compressor 40 includes a compressor, an air compressor 40 motor and an air compressor 40 controller, the air compressor 40 motor is electrically connected with the compressor, the air compressor 40 controller is electrically connected with the air compressor 40 motor and is electrically connected with the energy storage unit 30, and the energy storage unit 30 is used for providing electric energy to the air compressor 40 controller and storing redundant electric energy of the air compressor 40 controller.
Specifically, as shown in fig. 1, in an embodiment, the battery management unit 20 is configured to monitor and control an operation parameter of the energy storage unit 30, and the battery management unit 20 is configured to control the operation parameter of the fuel cell stack unit 10 according to the operation parameter of the energy storage unit 30.
The battery management unit 20 is further configured to monitor the voltage, current and temperature of the energy storage unit 30, accurately estimate the state of charge SOC of the energy storage unit 30, and perform energy balance between the energy storage batteries of the energy storage unit 30 according to the data information collected in real time.
Specifically, in one embodiment, the fuel cell power system 100 further includes a cooling unit and a hydrogen delivery unit. The cooling unit is used for cooling and radiating the fuel cell stack unit 10, and the hydrogen gas delivery unit is used for delivering hydrogen gas to the anode of the fuel cell stack unit 10.
As shown in fig. 2, there is provided a method for controlling output power of a fuel cell power system 100, which is applicable to the above-mentioned fuel cell power system 100, comprising the steps of:
Step one: obtaining a target output power of the fuel cell power system 100 using the battery management unit 20;
Step two: the battery management unit 20 determines an air compressor 40 control signal according to the target output power, and adjusts operation parameters of the air compressor 40 based on the air compressor 40 control signal, wherein the sum of the output power of the fuel cell stack unit 10 and the output power of the energy storage unit 30 is the actual output power of the fuel cell power system 100, so that the actual output power tends to the target output power; wherein, the control signal of the air compressor 40 and the target output power meet a preset output function.
Specifically, the fuel cell power system 100 of the present invention includes the fuel cell stack unit 10, the battery management unit 20, the energy storage unit 30 and the air compressor 40, after the target output power is obtained in the above step one, the battery management unit 20 obtains a corresponding control signal of the air compressor 40 according to a preset output function between the target output power and the target output power, and adjusts the air compressor 40 based on the control signal of the air compressor 40, so as to change the intake air flow of the fuel cell stack unit 10, so that the output power of the fuel cell stack unit 10 is changed, and meanwhile, the battery management unit 20 may also control the output power of the energy storage unit 30, so that the actual output power tends to the target output power.
It should be noted that the present invention is intended to include, but not limited to, making the difference between the output power of the fuel cell and the target output power small.
As a preferred solution, the present invention can make the actual output power of the fuel cell power system 100 the same as the target output power based on the control signal of the air compressor 40 obtained by the preset output function, so as to realize effective control of the actual output power of the fuel cell power system 100.
In the above-mentioned output power control method of the fuel cell power system 100, under the condition of confirming the target output power, the preset output function is utilized to regulate and control the control signal of the air compressor 40, so that the actual power output requirement can be solved according to the output function in different application scenarios, the application range is wide, the control implementation effect is good, and the energy storage unit 30 and the fuel cell stack unit 10 jointly output electric energy to the outside, so that the system has the advantages of stable operation voltage, wider operation fault tolerance, reduced energy waste and the like.
In a preferred embodiment, the control method further comprises:
the back pressure valve and/or the exhaust valve are adjusted according to the changing state of the fuel cell power system 100 so that the system state satisfies the preset state demand.
Specifically, when the target output power of the hydrogen fuel cell system is obtained in the first step and the operation parameters of the air compressor 40 are adjusted based on the control signal of the air compressor 40 in the second step, the system state of the hydrogen fuel cell system changes, that is, the intake air flow rate input into the fuel cell stack unit 10 changes after the air compressor 40 is adjusted. In this embodiment, the back pressure valve and/or the exhaust valve are/is adjusted in a follow-up manner by following the change of the air flow, so that the air pressure is adjusted to make the system state meet the preset state requirement.
Further, for example, when the target output power of the current step is greater than the actual output power of the previous step, the current step obtains the target output power, and obtains a corresponding control signal of the air compressor 40 based on a preset output function to adjust the operation parameters of the air compressor 40, so that the intake air flow is increased; after the system detects that the airflow quantity is increased, the opening of the back pressure valve is adjusted, so that the air pressure in the system is stable. The invention can also carry out the follow-up adjustment of the exhaust valve independently or simultaneously adjust the back pressure valve and the exhaust valve so as to stabilize the air pressure in the system.
Specifically, the state requirement is a requirement for enabling the hydrogen fuel cell system to normally and stably operate, for example, a requirement for meeting a humidity change requirement of the fuel cell stack unit 10, and a person skilled in the art can adjust a follow-up adjustment strategy of the back pressure valve and the exhaust valve according to the characteristics of the hydrogen fuel cell system, so that the follow-up adjustment of the back pressure valve and/or the exhaust valve meets a preset state requirement.
In another preferred embodiment, the control method further comprises:
Obtaining deviation information of a class II variable and a preset characteristic curve output by the hydrogen fuel cell; the electric loop of the hydrogen fuel cell system is regulated according to the deviation information, so that the first class variable and the second class variable tend to be on a preset characteristic curve.
In this embodiment, the characteristic curves are curves directly or indirectly related to the first class variable and the second class variable, and illustratively, the abscissa and the ordinate of the characteristic curves are the first class variable and the second class variable respectively, so as to define the first class variable and the second class variable.
For convenience of explanation, as shown in fig. 3, in the case that the state parameter of the fuel cell power system 100 is unchanged, each of the one type of variables may correspond to one type of variable within a reasonable range of one type of variables, and the correspondence forms a series of one type of variable-two type of variable fixed condition curves corresponding to fixed conditions, hereinafter referred to as condition curves, and the change of the hydrogen fuel cell state may cause the one type of variable and the two type of variable to change on the condition curves; under the condition that one type of variable and the control variable are unchanged, the output control circuit of the hydrogen fuel cell changes to cause the change of the two types of variables; in the case where the control variable is unchanged, a change in the state parameter of the hydrogen fuel cell results in a change in the first-class variable and the second-class variable. For ease of illustration, the following examples are presented with a class one variable and a class two variable compliance curve. The invention is not limited to the case where one type of variable and two types of variables conform to a conditional curve. When the first-class variable and the second-class variable do not accord with the condition curve, the person skilled in the art can also adjust the control variable according to the information of the hydrogen fuel cell, so that the first-class variable and the second-class variable accord with the preset characteristic curve.
Specifically, the preset one-class variable-two-class variable characteristic curve is hereinafter referred to as a characteristic curve, is not overlapped with any one of the condition curves, is intersected with a series of condition curves, and has only a limited intersection point with each intersected condition curve; in the running process of the system, when the actual values of the first-class variable and the second-class variable deviate from the characteristic curve, the control variable is adjusted according to the deviation direction and the deviation, so that the first-class variable and the second-class variable output by the hydrogen fuel cell are returned to the characteristic curve.
Specifically, in one embodiment, one type of variable is an output current or an output current density of the fuel cell power system 100, or a variable calculated therefrom, the output current of the fuel cell power system 100 is determined according to the output current of the fuel cell unit and the output current of the energy storage unit 30, and the output current density of the fuel cell power system 100 is determined according to the output current density of the fuel cell unit and the output current density of the energy storage unit 30;
And, the second type of variable is an output voltage, an output power, or an internal resistance compensation output voltage of the fuel cell power system 100, or a variable calculated therefrom, the output voltage of the fuel cell power system 100 is determined according to the output voltage of the fuel cell unit and the output voltage of the energy storage unit 30, the output power of the fuel cell power system 100 is determined according to the output power of the fuel cell unit and the output power of the energy storage unit 30, and the internal resistance compensation output voltage of the fuel cell power system 100 is determined according to the internal resistance compensation output voltage of the fuel cell unit and the internal resistance compensation output voltage of the energy storage unit 30.
In order to realize the adjustment of the first variable and the second variable, a negative feedback control method or a positive feedback control method can be adopted to control the control variable, wherein the control aims at enabling the first variable and the second variable to tend to the characteristic curve.
In this embodiment, the following parameters are taken as examples of the fuel cell power system 100: the first type of variable is the output current of the fuel cell power system 100, the second type of variable is the output voltage of the fuel cell power system 100, and the first type of variable and the second type of variable are adjusted by changing the duty ratio of the output switch of the direct current transformer; the output current and output voltage of the fuel cell power system 100 are maintained on a preset characteristic curve by automatic feedback control of the output duty ratio of the dc transformer.
Taking a negative feedback control method and taking a working state as a reference state as an example, the control process comprises the following steps:
The output current and output voltage of the fuel cell power system 100 are monitored in real time, and compared with a preset characteristic curve, the output current and output voltage of the fuel cell power system 100 are adjusted at the input side of the fuel cell power system 10 where the dc transformer FDC is output, the adjustment process includes:
If the output current and the output voltage are located below the pile target volt-ampere characteristic curve, the fuel pile unit 10 outputs a direct-current transformer to reduce the output current by adjusting the duty ratio of the internal direct-current transformation circuit, so that the output voltage is improved and is close to the characteristic curve;
if the output current and the output voltage are above the stack target volt-ampere characteristic curve, the fuel cell stack unit 10 outputs a dc transformer that increases the output current by adjusting the duty ratio of the internal dc transformation circuit, thereby decreasing the output voltage to approach the characteristic curve.
In this embodiment, on the input side of the dc transformer output by the fuel cell stack unit 10, the output current and output voltage of the fuel cell power system 100 are adjusted, and under the condition that the operating condition parameters of the hydrogen fuel cell are maintained or changed, the current and voltage values on the input side are always located on the stack target volt-ampere characteristic curve by adjusting the duty ratio of the electronic devices of the Buck-Boost circuit, so that the electric energy is output according to the preset output performance of the fuel cell power system 100.
This embodiment ensures that the current and voltage values entering the input side of the transformer are located on the preset volt-ampere characteristic curve of the stack, so that the entire fuel cell power system 100 always maintains the preset output characteristic, and not only realizes millisecond response time through the duty ratio control of the transformer side, but also improves the stability and service life of the operation of the fuel cell stack unit 10.
Specifically, this embodiment sets the target parameter of the FDC control to the distance of the current voltage output from the fuel cell stack unit 10 from the target voltammogram on the voltammogram; if the actual output current voltage of the fuel cell stack unit 10 is below the target curve, reducing the output electric energy of the fuel cell stack unit 10 through the FDC so as to reduce the actual output current of the fuel cell stack unit 10, and increasing the voltage to approach the target curve from below; if the actual output current voltage of the fuel cell stack unit 10 is above the target curve, the fuel cell stack unit 10 outputs electric energy by the FDC to increase the actual output current of the fuel cell stack unit 10, and the voltage decreases to approach the target curve from above.
In this embodiment, the FDC is used as an important part of the control of the fuel cell stack unit 10, and since the response speed of the circuit in the FDC is far higher than that of the components of the hydrogen circuit and the air circuit, the fast response characteristic of the FDC can be used to realize that the actual output of the fuel cell stack unit 10 is locked on the characteristic curve in the process of dynamic change of the components of the hydrogen circuit and the air circuit, so that the operation stability and the service life of the fuel cell stack unit 10 are improved.
When in an operation state, the duty ratio of the output DC transformer of the fuel cell stack unit 10 is adjusted by calculating the difference value between the output current and the output voltage of the fuel cell stack unit 10 and the current stack target volt-ampere characteristic curve;
the difference value is a voltage difference under the same current, a current difference under the same voltage, or a value calculated by adopting the voltage difference and the current difference.
If the voltage difference is used as the difference value, the duty ratio adjustment process of the output dc transformer of the fuel cell stack unit 10 is specifically:
Calculating the difference value between the output current and the output voltage of the fuel cell stack unit 10 and the corresponding point in the target volt-ampere characteristic curve, wherein the difference value is a voltage difference;
if the difference value is equal to zero, i.e. the actual output current and voltage of the fuel cell stack unit 10 are in the target volt-ampere characteristic curve, the duty ratio is kept unchanged;
If the difference value is greater than zero, that is, the actual output current and voltage of the fuel cell stack unit 10 are above the target volt-ampere characteristic curve, the duty ratio is adjusted, and the output current of the fuel cell stack unit 10 is increased;
If the difference value is smaller than zero, i.e. the actual output current and voltage of the fuel cell stack unit 10 is below the target volt-ampere characteristic, the duty cycle is adjusted to reduce the output current of the fuel cell stack unit 10.
In the invention, the response speeds of the air 40, the battery management unit 20, the energy storage unit 30 and the fuel cell stack unit 10 in the fuel cell power system 100 are reasonably distributed, so that the follow-up control of a gas loop and the cooperative characteristic curve control of an electric power loop are realized, the power regulation process of the fuel cell power system 100 is optimized based on the response speeds of different levels, the multi-factor power control of the fuel cell power system 100 is realized, the control strategy is flexible, the fluctuation of the performance of the fuel cell stack is small, and the method is suitable for the control of the fuel cell power system 100 with different application requirements.
In another preferred embodiment, the output function is a monotonic function. In the invention, the relation between the target output power and the control signal of the air compressor 40 is monotonically increasing or decreasing, so that the output function is a monotonic function, and the output function of the target output power and the control signal of the air compressor 40 can be calibrated according to specific parameters of the hydrogen fuel system.
In another preferred embodiment, the air compressor 40 control signal is the torque, rotational speed, current, power or PWM duty cycle of the air compressor 40, or a variable calculated therefrom. The control signal of the air compressor 40 can effectively regulate the air compressor 40, regulate the rotation speed, the power or the flow of the air compressor 40, change the operation parameters of the fuel cell stack unit 10 and further regulate the output power.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
The foregoing describes in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations can be made in accordance with the concepts of the invention by one of ordinary skill in the art without undue burden. Therefore, all technical solutions which can be obtained by logic analysis, reasoning or limited experiments based on the prior art by the person skilled in the art according to the inventive concept shall be within the scope of protection defined by the claims.
Claims (6)
1. The fuel cell power system is characterized by comprising a fuel cell stack unit, a battery management unit, an energy storage unit, an air compressor and an external load, wherein an outlet of the air compressor is communicated with an air inlet of the fuel cell stack unit and is used for providing high-pressure air for the fuel cell stack unit, the battery management unit is respectively and electrically connected with the energy storage unit and the fuel cell stack unit and is used for controlling the output power of the energy storage unit and the fuel cell stack unit, the energy storage unit is electrically connected with the air compressor and is used for providing electric energy for the air compressor and storing redundant electric energy of the air compressor, the external load is electrically connected with the battery management unit, and the battery management unit is also used for providing electric energy for the external load;
The fuel cell power system further comprises an output power monitoring unit, wherein the output power monitoring unit is electrically connected with the fuel cell stack unit and the battery management unit and is used for acquiring the output power of the fuel cell stack unit and transmitting an output power signal to the battery management unit so that the battery management unit controls the energy storage unit and the fuel cell stack unit to release electric energy according to the output power signal when the output power of the fuel cell stack unit is smaller than the required power of the external load, the electric energy of the air compressor is provided by the energy storage unit, and controls the fuel cell stack unit to release electric energy and transmit redundant electric energy to the energy storage unit when the output power of the fuel cell stack unit is larger than the required power of the external load;
The output power monitoring unit is also electrically connected with the air compressor and is used for transmitting output power signals to the air compressor.
2. The fuel cell power system according to claim 1, further comprising a fuel unidirectional DC/DC converter, the fuel cell stack unit being electrically connected to the battery management unit through the fuel unidirectional DC/DC converter for providing direct current electrical energy to the battery management unit.
3. The fuel cell power system according to claim 1, wherein the energy storage unit includes an energy storage battery and an energy storage unidirectional DC/DC converter, the energy storage battery being electrically connected with the battery management unit through the energy storage unidirectional DC/DC converter.
4. The fuel cell power system according to claim 3, wherein the energy storage unit further includes a motor controller having a kinetic energy recovery function, and the energy storage battery is electrically connected to the air compressor through the motor controller.
5. A method of controlling the output power of a fuel cell power system, characterized by using the fuel cell power system according to any one of claims 1 to 4, comprising the steps of:
Acquiring target output power of a fuel cell power system by adopting a battery management unit;
The battery management unit determines an air compressor control signal according to the target output power, adjusts operation parameters of the air compressor based on the air compressor control signal, and enables the sum of the output power of the fuel cell stack unit and the output power of the energy storage unit to be actual output power so that the actual output power tends to the target output power;
Wherein, the control signal of the air compressor accords with a preset output function with the target output power;
The control method further includes:
Acquiring deviation information of a class-II variable and a class-II variable which are output by the fuel cell power system and a preset characteristic curve by adopting the battery management unit, wherein the class-II variable is output current or output current density of the fuel cell power system or a variable obtained by calculation, the output current of the fuel cell power system is determined according to the output current of the fuel cell unit and the output current of the energy storage unit, the output current density of the fuel cell power system is determined according to the output current density of the fuel cell unit and the output current density of the energy storage unit, the class-II variable is output voltage, output power or internal resistance compensation output voltage of the fuel cell power system or a variable obtained by calculation, the output voltage of the fuel cell power system is determined according to the output voltage of the fuel cell unit and the output voltage of the energy storage unit, the internal resistance compensation output voltage of the fuel cell power system is determined according to the internal resistance compensation output voltage of the fuel cell unit and the output voltage of the energy storage unit, and the class-II variable is intersected with the characteristic curve;
And the electric loop of the fuel cell power system adjusts the duty ratio of an internal direct current transformation circuit of the direct current transformer output by the fuel cell stack unit according to the deviation information, so that the first-class variable and the second-class variable tend to be on a preset characteristic curve.
6. The method of claim 5, wherein the air compressor control signal is an air compressor torque, rotational speed, current, power, or PWM duty cycle, or a variable calculated therefrom.
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| CN111244504A (en) * | 2020-03-23 | 2020-06-05 | 谭明波 | Fuel cell stack activation device |
| CN113782791A (en) * | 2021-08-02 | 2021-12-10 | 佛山仙湖实验室 | Power control method and system for vehicle proton exchange membrane fuel cell |
| CN115096368A (en) * | 2022-07-08 | 2022-09-23 | 江西清华泰豪三波电机有限公司 | Fuel cell comprehensive test platform and electric pile temperature control method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111244504A (en) * | 2020-03-23 | 2020-06-05 | 谭明波 | Fuel cell stack activation device |
| CN113782791A (en) * | 2021-08-02 | 2021-12-10 | 佛山仙湖实验室 | Power control method and system for vehicle proton exchange membrane fuel cell |
| CN115096368A (en) * | 2022-07-08 | 2022-09-23 | 江西清华泰豪三波电机有限公司 | Fuel cell comprehensive test platform and electric pile temperature control method thereof |
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