Fuel cell system and electric vehicle

Abstract

The utility model provides a fuel cell system and an electric vehicle. The fuel cell system includes: a stack configured to output a current through a power supply circuit; the impedance detection unit comprises a converter electrically connected with the power supply circuit, a storage battery electrically connected with the converter and a current sensor arranged on the power supply circuit; the control unit comprises a current instruction module which is in signal connection with the converter and a current correction module which is in signal connection with the current instruction module and the current sensor; the current instruction module is configured to control the converter to convert electric energy from the storage battery into alternating current input to the electric pile through the power supply circuit according to an alternating current waveform; the current correction module is configured to determine a corrected current signal according to a current signal measured by the current sensor and a target current signal selected from the alternating current waveform.

Description

Technical Field

[0001] This disclosure relates to the field of fuel cell technology, and more specifically, to a fuel cell system and an electric vehicle using the fuel cell system as a power source. Background Technology

[0002] Fuel cells have become one of the main power generation technologies due to their high power generation efficiency, low environmental pollution, and high specific energy. As a typical fuel cell, the proton exchange membrane fuel cell (PEMFC) is a popular type of fuel cell used in vehicles. PEMFCs generally consist of a solid polymer electrolyte proton exchange membrane, such as a perfluorosulfonic acid membrane. The anode and cathode typically comprise finely divided catalyst particles, usually platinum (Pt), supported on carbon particles and mixed with ionomers. The catalyst mixture is deposited on opposite sides of the membrane. The combination of the anode catalyst mixture, the cathode catalyst mixture, and the membrane defines the catalyst coating (CCM), while the catalyst coating and the two gas diffusion layers on either side define the membrane electrode assembly (MEA).

[0003] A fuel cell stack includes a series of bipolar plates positioned between several MEAs (Mechanical Exchange Assemblies) within the stack, with the bipolar plates and MEAs located between two end plates. Each bipolar plate includes an anode side and a cathode side for adjacent fuel cell units within the stack. An anode gas flow channel is provided on the anode side of the bipolar plate, allowing anode reactant gases to flow to the corresponding MEA. A cathode gas flow channel is provided on the cathode side of the bipolar plate, allowing cathode reactant gases to flow to the corresponding MEA. The anode and cathode gases flowing to both sides of the MEA diffuse to both sides of the proton exchange membrane and undergo an electrochemical reaction in the presence of a catalyst to generate electrical energy, while simultaneously producing water and heat as byproducts.

[0004] Water produced during the electrochemical reaction affects the humidity within the fuel cell stack. Excessive humidity can hinder the diffusion of anode and cathode gases, reducing the efficiency of the electrochemical reaction. Conversely, insufficient humidity can significantly increase the resistance of the proton exchange membrane due to dryness, also reducing efficiency. Therefore, monitoring the humidity within the fuel cell stack is crucial for maintaining its efficiency. Electrochemical impedance spectroscopy (EIS) is often used to determine the stack's impedance and assess its humidity. However, EIS requires an AC current input to the stack, resulting in a current signal measured in the power supply circuit that includes not only the current generated by the stack but also the AC current input. Using this current signal as feedback for stack control reduces the accuracy of control and may even prevent the stack from outputting the desired power.

[0005] Therefore, there is an urgent need in this field for a technical solution that can accurately assess the humidity inside the fuel cell stack and accurately control the fuel cell stack. Utility Model Content

[0006] To address the problems in the prior art, this disclosure proposes an improved fuel cell system comprising: a fuel cell stack configured to output current through a power supply circuit; an impedance detection unit including a converter electrically connected to the power supply circuit, a battery electrically connected to the converter, and a current sensor disposed on the power supply circuit; and a control unit including a current command module signal-connected to the converter and a current correction module signal-connected to the current command module and the current sensor, wherein the current command module is configured to control the converter to convert electrical energy from the battery into an alternating current input to the fuel cell stack through the power supply circuit according to an alternating current waveform, and wherein the current correction module is configured to determine a corrected current signal based on a current signal measured by the current sensor and a target current signal selected from the alternating current waveform.

[0007] According to an optional embodiment of this disclosure, the impedance detection unit further includes a voltage sensor disposed on the power supply circuit, and the control unit further includes an impedance calculation module connected to the current sensor and the voltage sensor signals. The impedance calculation module is configured to calculate the impedance of the stack based on the current signal measured by the current sensor and the voltage signal measured by the voltage sensor.

[0008] According to an optional embodiment of the present disclosure, the fuel cell system further includes a cathode gas supply unit configured to supply cathode gas to the stack, an anode gas supply unit configured to supply anode gas to the stack, and a thermal management unit configured to regulate the temperature within the stack.

[0009] According to an optional embodiment of this disclosure, the current correction module is configured to use the difference between the current signal measured by the current sensor and the target current signal as the corrected current signal.

[0010] According to an alternative embodiment of this disclosure, the current correction module is configured to select a point before a delay time from the alternating current waveform as the target current signal.

[0011] According to an alternative embodiment of this disclosure, the control unit is configured to use the corrected current signal as a feedback signal to perform closed-loop control of the current output by the fuel cell stack.

[0012] Similarly, to address the problems in the prior art described above, this disclosure also proposes an improved electric vehicle, comprising: a fuel cell system as described in this disclosure; a DC / DC converter electrically connected to a power supply circuit of the fuel cell system and configured to receive current output from the fuel cell stack of the fuel cell system through the power supply circuit; an electronic control unit signal-connected to a current correction module of the fuel cell system and configured to perform closed-loop control of the current output from the fuel cell stack using a corrected current signal determined by the current correction module as a feedback signal; and a power battery electrically connected to the DC / DC converter, wherein the DC / DC converter is configured to convert electrical energy from the fuel cell stack into electrical energy suitable for supplying to the power battery.

[0013] According to an alternative embodiment of this disclosure, the electric vehicle further includes an inverter electrically connected to the DC / DC converter and a traction motor electrically connected to the inverter, the DC / DC converter being configured to convert electrical energy from the fuel cell stack into electrical energy suitable for supplying to the inverter.

[0014] According to an optional embodiment of this disclosure, the DC / DC converter, the power battery, and the electronic control unit respectively constitute the converter, the battery, and the control unit of the fuel cell system.

[0015] According to an optional embodiment of this disclosure, the current command module of the control unit is signal-connected to the current correction module and configured to use the corrected current signal as a feedback signal to perform closed-loop control on the current output by the fuel cell stack.

[0016] This disclosure may be embodied in the illustrative embodiments shown in the accompanying drawings. However, it should be noted that the drawings are merely illustrative, and any variations contemplated under the teachings of this disclosure should be considered to be included within the scope of this disclosure. Attached Figure Description

[0017] The accompanying drawings illustrate exemplary embodiments of this disclosure. These drawings should not be construed as necessarily limiting the scope of this disclosure, wherein:

[0018] Figure 1 This is a schematic block diagram of a fuel cell system according to one embodiment of the present disclosure;

[0019] Figure 2 yes Figure 1 The schematic equivalent circuit diagram of the fuel cell stack of the fuel cell system shown is shown.

[0020] Figure 3 yes Figure 1A schematic block diagram of the fuel cell stack, impedance detection unit, and control unit of the fuel cell system shown; and

[0021] Figure 4 This is one embodiment of the present disclosure, including Figures 1-3 The diagram shows a schematic block diagram of an electric vehicle with a fuel cell system. Detailed Implementation

[0022] Further features and advantages of this disclosure will become more apparent from the following description with reference to the accompanying drawings. Exemplary embodiments of this disclosure are shown in the drawings, and the drawings are not necessarily drawn to scale. However, this disclosure can be implemented in many different forms and should not be construed as necessarily limited to the exemplary embodiments shown herein. Rather, these exemplary embodiments are provided merely to illustrate this disclosure and to convey the spirit and essence of this disclosure to those skilled in the art.

[0023] This disclosure aims to provide an improved fuel cell system and an electric vehicle including the fuel cell system. Due to its novel design, the fuel cell system according to this disclosure can accurately detect both the electrochemical impedance spectroscopy (EIS) of the fuel cell stack and the output current of the stack. Accurate detection of the EIS helps to accurately assess the humidity within the stack, thereby avoiding conditions such as membrane drying or flooding that affect stack operation. The output current of the stack is one of the important parameters required for controlling the fuel cell system; therefore, accurate detection of the stack output current helps to accurately control the fuel cell system, enabling it to output the desired power to accurately meet the power request of the load. In other words, the fuel cell system according to this disclosure, due to its novel design, can avoid the influence of the detection of the stack's EIS on the control of the fuel cell system, thus enabling accurate assessment and control of the fuel cell system simultaneously.

[0024] Various alternative, but non-limiting, embodiments of the fuel cell system and electric vehicle according to this disclosure are described in detail below with reference to the accompanying drawings.

[0025] refer to Figure 1 A schematic block diagram of a fuel cell system according to one embodiment of the present disclosure is shown. Figure 1As shown, the fuel cell system 10 generally includes a stack 100, a cathode gas supply unit 200, an anode gas supply unit 300, and a thermal management unit 400. The cathode gas supply unit 200 can supply cathode gas (e.g., air or other oxygen-containing gas) to the stack 100, and the anode gas supply unit 300 can supply anode gas (e.g., hydrogen or other hydrogen-containing gas) to the stack 100, so that the stack 100 can generate electrical energy internally through the electrochemical reaction of the cathode gas and the anode gas. The thermal management unit 400 can dissipate the heat generated by the electrochemical reaction to prevent the stack 100 from overheating.

[0026] Specifically, the cathode gas supply unit 200 includes a cathode gas supply line 210 and a cathode gas discharge line 220 in fluid communication with the fuel cell stack 100, and further includes a filter 211, a compressor 212, and a supply valve 213 disposed on the cathode gas supply line 210, and a discharge valve 221 disposed on the cathode gas discharge line 220. When the fuel cell stack 100 is operating, after starting the compressor 212 and opening the supply valve 213 and the discharge valve 221, the cathode gas supply line 210 can deliver air from the atmosphere, filtered by the filter 211, to the compressor 212, and then deliver the air compressed by the compressor 212 to the fuel cell stack 100, while the cathode gas discharge line 220 can discharge air from the fuel cell stack 100 to the atmosphere. In this configuration, air can flow through the fuel cell stack 100, and oxygen in the air can participate in the electrochemical reaction inside the fuel cell stack 100 as a cathode gas. In addition, by adjusting the speed of the drive motor of the compressor 212 and the valve opening of the supply valve 213 and the discharge valve 221, the air pressure inside the fuel cell stack 100 can be changed, which helps to adjust the rate of the electrochemical reaction and thus control the output power of the fuel cell stack 100. Specifically, since the air compressed by compressor 212 is high-temperature and dry, and the air discharged from fuel cell stack 100 carries water generated by the electrochemical reaction, the cathode gas supply unit 200 also includes a humidifier 230 to prevent the proton exchange membrane inside fuel cell stack 100 from drying out due to the supply of high-temperature and dry air. The humidifier 230 is installed on both cathode gas supply line 210 and cathode gas discharge line 220 and is configured to allow the air supplied by cathode gas discharge line 220 to exchange moisture with the air supplied by cathode gas supply line 210. Thus, the water generated by the electrochemical reaction can be used to humidify the air supplied to fuel cell stack 100, thereby preventing the proton exchange membrane inside fuel cell stack 100 from drying out. As described in more detail below, such membrane drying will significantly increase the ohmic impedance of fuel cell stack 100, thereby seriously affecting the output power of fuel cell stack 100.

[0027] The anode gas supply unit 300 includes an anode gas supply line 310 and an anode gas discharge line 320 that are in fluid communication with the fuel cell stack 100. It also includes a hydrogen storage tank 311, a supply valve 312 and an injector 313 installed on the anode gas supply line 310, a discharge valve 321 installed on the anode gas discharge line 320, and a circulation pump 330 connected between the anode gas supply line 310 and the anode gas discharge line 320. When the fuel cell stack 100 is running, after starting the circulation pump 330, opening the supply valve 312, and closing the discharge valve 321, the anode gas supply line 310 can deliver hydrogen from the hydrogen storage tank 311 to the injector 313, and then deliver the hydrogen accelerated by the injector 313 to the fuel cell stack 100. The anode gas discharge line 320 can deliver hydrogen from the fuel cell stack 100 to the circulation pump 330, which in turn can deliver hydrogen from the anode gas discharge line 320 to the anode gas supply line 310, which in turn can deliver hydrogen from the circulation pump 330 to the fuel cell stack 100. This not only supplies hydrogen to the fuel cell stack 100 but also allows for the recovery and reuse of hydrogen not consumed by the fuel cell stack 100. Of course, when it is necessary to discharge hydrogen rather than recover it, the discharge valve 321 can be opened so that the anode gas discharge line 320 can discharge hydrogen from the fuel cell stack 100 to the atmosphere. In this configuration, hydrogen can flow through the fuel cell stack 100 and participate in the electrochemical reaction inside the stack 100 as an anode gas. Furthermore, by adjusting the speed of the drive motor of the circulation pump 330 and the opening degrees of the supply valve 312 and the discharge valve 321, the hydrogen pressure inside the fuel cell stack 100 can be changed, which helps to adjust the rate of the electrochemical reaction and thus control the power output of the fuel cell stack 100.

[0028] The thermal management unit 400 includes a cooling circuit 410 in fluid communication with the fuel cell stack 100, and also includes a radiator 411 and a drive pump 412 disposed on the cooling circuit 400. During operation of the fuel cell stack 100, after the drive pump 412 is started, the cooling circuit 410 can deliver coolant to circulate between the radiator 411 and the fuel cell stack 100. In this configuration, the coolant can absorb the heat generated by the electrochemical reaction inside the fuel cell stack 100 and dissipate it at the radiator 411, thereby ensuring a uniform temperature distribution inside the fuel cell stack 100 to avoid localized hot spots and maintaining the temperature inside the fuel cell stack 100 at a suitable temperature required for the electrochemical reaction to improve the efficiency of the electrochemical reaction. Of course, when cold-starting in a low-temperature environment, the internal temperature of the fuel cell stack 100 may be lower than the suitable temperature. In this case, the radiator 411 can be bypassed by the three-way valve 413 set on the cooling circuit 410 to avoid the radiator 411 dissipating the heat of the coolant, thereby causing the internal temperature of the fuel cell stack 100 to rise rapidly to the suitable temperature, so as to improve the success rate of cold start and shorten the time required for cold start.

[0029] Furthermore, after the cathode gas supply unit 200 supplies cathode gas (i.e., oxygen) to the fuel cell stack 100 and the anode gas supply unit 300 supplies anode gas (i.e., hydrogen) to the fuel cell stack 100, the cathode gas and anode gas diffuse into the cathode catalyst layer and anode catalyst layer on both sides of each proton exchange membrane, respectively, inside the fuel cell stack 100. At the anode catalyst layer, the anode gas decomposes into protons and electrons under the action of the catalyst material (i.e., undergoes an oxidation reaction: 2H₂→4H₂). + +4e - ), of which, proton (H + Electrons can pass through the proton exchange membrane to reach the cathode catalyst layer, but electrons (e) - Because it cannot pass through the proton exchange membrane, the gas can only reach the cathode catalyst layer through an external circuit. At the cathode catalyst layer, the cathode gas combines with protons and electrons under the action of the catalyst material to generate water (i.e., a reduction reaction occurs: O₂ + 4H₂O). + +4e - →2H2O). In the above manner, the fuel cell stack 100 can convert chemical energy into electrical energy through the electrochemical reaction (also known as redox reaction) of the anode gas and cathode gas, thereby supplying power to the load on the external circuit. At the same time, water and heat are generated as byproducts. Water is mainly generated at the cathode catalyst layer and will be discharged from the fuel cell stack 100 with the cathode gas, while heat will be absorbed by the coolant and discharged from the fuel cell stack 100 with the coolant.

[0030] It is worth noting that the efficiency of the electrochemical reaction in converting chemical energy into electrical energy is mainly affected by the activation energy barrier of the electrochemical reaction (i.e., the energy threshold required to carry out the electrochemical reaction), the resistance of components such as the proton exchange membrane, the resistance of the interfaces between various components, and the insufficient supply of anolyte and cathode gases. All of these factors will cause the actual output voltage of the fuel cell stack 100 to be lower than the theoretical voltage. In other words, each of these factors will generate impedance, including charge transfer impedance due to the activation energy barrier of the electrochemical reaction, ohmic impedance due to resistance, and diffusion impedance due to insufficient supply of anolyte and cathode gases. After converting these impedances into resistances, the equivalent circuit of the fuel cell stack 100 can be obtained. (Reference) Figure 2 , which shows Figure 1 The diagram shows a schematic equivalent circuit of the fuel cell stack in the fuel cell system. Figure 2As shown, the equivalent circuit of fuel cell stack 100 includes a power supply 110, a resistor R1 connected in series with the power supply 110, and a capacitor C and a resistor R2 connected in parallel and in series with the resistor R1. The resistor R1 corresponds to the resistance of the components such as the proton exchange membrane itself and the resistance of the interfaces between the components; that is, the resistor R1 is the resistance converted from ohmic impedance. The resistor R2 corresponds to the resistance converted from charge transfer impedance and diffusion impedance. The capacitor C corresponds to the capacitance formed by the interfaces between the cathode catalyst layer and the proton exchange membrane, and between the anode catalyst layer and the proton exchange membrane. From this equivalent circuit, it can be seen that if alternating currents of different frequencies are input to fuel cell stack 100, the impedance of fuel cell stack 100 at different frequencies can be determined. If the impedance at each frequency is expressed in complex form, a Nyquist plot of the impedance can be drawn on a coordinate system with resistance as the horizontal axis and reactance as the vertical axis. From this, the resistance values ​​of resistors R1 and R2 can be calculated. For example, if an AC current with a frequency of 0 is input into the fuel cell stack 100, then the capacitor C is equivalent to an open circuit, and the impedance of the fuel cell stack 100, expressed in complex form, has only a real part, which is equivalent to the sum of the resistances R1 and R2. If an AC current with a frequency of ∞ is input into the fuel cell stack 100, then the capacitor C is equivalent to a short circuit, and the impedance of the fuel cell stack 100, expressed in complex form, also has only a real part, which is equivalent to the resistance of R1. Therefore, by inputting AC currents of different frequencies into the fuel cell stack 100 and determining the impedance of the fuel cell stack 100 at different frequencies, the resistances of R1 and R2 can be calculated. It should be noted that the resistances of R1 and R2 are important parameters for evaluating the internal humidity of the fuel cell stack 100. Specifically, since the humidity of the proton exchange membrane is negatively correlated with its ohmic impedance, and therefore negatively correlated with the resistance R1, if the calculated resistance R1 exceeds a threshold, the ohmic impedance is considered too high, the humidity of the proton exchange membrane is too low, and membrane dryness has occurred within the fuel cell stack 100. Furthermore, since the diffusion of anodic and cathodic gases is primarily hindered by moisture within the fuel cell stack 100, the amount of water within the stack is positively correlated with its diffusion impedance, and therefore positively correlated with the resistance R2. If the calculated resistance R2 exceeds a threshold, the amount of water within the fuel cell stack 100 is considered excessive and severely hinders the diffusion of cathodic and anodic gases, indicating flooding within the fuel cell stack 100. In summary, by monitoring the impedance of the fuel cell stack 100 at different frequencies, the humidity within the fuel cell stack 100 can be assessed (this technique can also be called electrochemical impedance spectroscopy (EIS)).

[0031] like Figure 1As shown, the fuel cell stack 100 is configured to output direct current through a power supply circuit 120, wherein the two output terminals of the fuel cell stack 100 are electrically connected to the positive and negative cables of the power supply circuit 120, respectively. To determine the impedance of the fuel cell stack 100 at different frequencies in order to assess the humidity within the fuel cell stack 100, the fuel cell system 10 also includes an impedance detection unit 500 for detecting the impedance of the fuel cell stack 100. The impedance detection unit 500 includes a converter 510 electrically connected to the power supply circuit 120, a battery 520 electrically connected to the converter 510, and a current sensor 530 and a voltage sensor 540 disposed on the power supply circuit 120. Additionally, the fuel cell system 10 also includes a control unit 600 for controlling the impedance detection unit 500. (Reference) Figure 3 , which shows Figure 1 The diagram shows a schematic block diagram of the fuel cell stack, impedance detection unit, and control unit of the fuel cell system. Figure 3As shown, the control unit 600 includes a current command module 610 connected to the converter 510 and an impedance calculation module 620 connected to the current sensor 530 and the voltage sensor 540. The current command module 610 is configured to generate an AC current waveform for detecting the impedance of the fuel cell stack 100. The converter 510 is configured to convert electrical energy from the battery 520 into AC current according to the AC current waveform generated by the command module 610 and input AC current to the fuel cell stack 100 through the power supply circuit 120. The current sensor 530 is configured to detect the current in the power supply circuit 120 (i.e., the current of the fuel cell stack 100), the voltage sensor 540 is configured to detect the voltage in the power supply circuit 120 (i.e., the voltage of the fuel cell stack 100), and the impedance calculation module 620 is configured to calculate the impedance of the fuel cell stack 100 based on the current signal measured by the current sensor 530 and the voltage signal measured by the voltage sensor 540. In this configuration, the current command module 610 can control the converter 510 to convert electrical energy from the battery 520 into AC current according to the generated AC current waveform, thereby superimposing AC current on the DC current in the power supply circuit 120, and inputting the AC current into the fuel cell stack 100 through the power supply circuit 120. This will cause the fuel cell stack 100 to superimpose an AC voltage related to its impedance and the AC current on the output DC voltage. The impedance calculation module 620 can determine the AC current and AC voltage through the current signal measured by the current sensor 530 and the voltage signal measured by the voltage sensor 540, and further calculate the impedance of the fuel cell stack 100 at different frequencies by performing a Fourier transform on the AC current and AC voltage and dividing them. In this case, the impedance of the fuel cell stack 100 at different frequencies will be expressed in complex form. Therefore, a Nyquist plot of the impedance of the fuel cell stack 100 can be plotted, that is, an impedance curve can be drawn in a coordinate system with resistance as the horizontal axis and reactance as the vertical axis. Based on the intersection of the impedance curve and the horizontal axis, the resistance values ​​of resistor R1, which reflects ohmic impedance, and resistor R2, which reflects diffusion impedance, in the equivalent circuit of the fuel cell stack 100 can be calculated. This allows for the assessment of humidity within the fuel cell stack 100. It is worth mentioning that although in the description of this disclosure, the AC current waveform used to detect the impedance of the fuel cell stack 100 is generated by the current command module 610, this is merely exemplary. In other embodiments, the AC current waveform may also be stored in memory beforehand and read by the current command module 610, or it may be generated by other modules and sent to the current quality module 610.

[0032] like Figure 1As shown, the control unit 600 is also signal-connected to the cathode gas supply unit 200, the anode gas supply unit 300, and the thermal management unit 400, and is configured to control the operation of these three units. Specifically, the direct current output by the fuel cell stack 100 is a crucial parameter for controlling the stack 100. For example, if the control unit 600 can use the direct current output by the stack 100 as a feedback signal to perform closed-loop control of the stack 100, the fuel cell system 10 can accurately output the desired power to meet the load's power request. However, as mentioned earlier, the current signal detected by the current sensor 530 includes not only the direct current output by the stack 100 but also the alternating current input to the stack 100 to determine its impedance. In this case, if the control unit 600 uses the current signal detected by the current sensor 530 as a feedback signal to perform closed-loop control of the stack 100, the aforementioned alternating current will become an error in the feedback signal, causing the fuel cell system 10 to fail to accurately output the desired power. Therefore, as... Figure 3 As shown, the control unit 600 also includes a current correction module 630, which is signal-connected to the current sensor 530 and the current command module 610. This current correction module 630 is configured to calculate a corrected current signal based on the AC current waveform generated by the current command module 610 and the current signal detected by the current sensor 530 (hereinafter referred to as the detected current signal). The control unit 600 is configured to control the fuel cell stack 100 based on the corrected current signal calculated by the current correction module 630. Specifically, the current correction module 630 can select a target current signal from the AC current waveform generated by the current command module 610. The converter 510 converts electrical energy from the battery 520 into AC current based on this target current signal. Furthermore, the current correction module 630 can use the difference between the detected current signal and the target current signal as the corrected current signal. In this configuration, the current correction module 630 can remove the AC current input to the fuel cell stack 100 to determine the impedance of the fuel cell stack 100 from the detected current signal, so that the calculated corrected current signal can accurately reflect the DC current output by the fuel cell stack 100. Therefore, by using the corrected current signal as a feedback signal to perform closed-loop control of the fuel cell stack 100, the error in the feedback signal is eliminated, and the control unit 600 can thus accurately control the fuel cell stack 100 so that the fuel cell system 10 accurately outputs the desired power to meet the power request of the load.

[0033] Specifically, the inventors of this application discovered that due to a system delay, there is a time delay (e.g., 5 μs) between the generation of the target current signal by the current command module 610 and the input of the AC current corresponding to the target current signal into the fuel cell stack 100 by the converter 510. In other words, after the current command module 610 generates the target current signal, the converter 510 will input the AC current corresponding to the target current signal into the fuel cell stack 100 only after the time delay. Therefore, the AC current in the detected current signal actually corresponds to the target current signal in the AC current waveform before the time delay. Therefore, in order to take the system delay into account, the current correction module 630 is configured to select the point before the time delay from the AC current waveform as the target current signal. Under this configuration, the correction of the detected current signal by the current correction module 630 can take the system delay into account, thereby more accurately removing the AC current used to determine the impedance of the fuel cell stack 100 from the detected current signal, so that the corrected current signal can more accurately reflect the DC current output by the fuel cell stack 100, which helps to control the fuel cell stack 100 more accurately.

[0034] refer to Figure 4 The embodiment of the present disclosure is shown, including... Figures 1-3 The diagram shows a schematic block representation of an electric vehicle equipped with a fuel cell system. Figure 4As shown, the electric vehicle 20 includes the fuel cell system 10 described in this disclosure, which serves as the power source for the electric vehicle 20. Furthermore, the converter 510 of the impedance detection unit 500 of the fuel cell system 10 is constituted by a DC / DC converter of the electric vehicle 20, the battery 520 is constituted by a power battery of the electric vehicle 20, and the control unit 600 is constituted by an electronic control unit (i.e., ECU) of the electric vehicle 20. A power supply circuit 120 electrically connects the fuel cell stack 100 to the converter 510. More specifically, the positive cable of the power supply circuit 120 electrically connects the positive output terminal of the fuel cell stack 100 to the positive input terminal of the converter 510, and the negative cable of the power supply circuit 120 electrically connects the negative output terminal of the fuel cell stack 100 to the negative input terminal of the converter 510, so that the fuel cell stack 100 inputs DC current to the converter 510 through the power supply circuit 120. Additionally, the electric vehicle 20 also includes an inverter 700 electrically connected to the converter 510 and a traction motor 800 electrically connected to the inverter 700. In this configuration, the current command module 610 is not only configured to control the converter 510 to convert electrical energy from the battery 520 into AC power based on the AC current waveform, but also signal-connected to the current correction module 630. It is configured to use the corrected current signal as feedback to control the DC current output by the fuel cell stack 100 through the converter 510, so that the fuel cell system 10 outputs the desired power to meet the load's power request. In this case, since the current command module 610 can use the corrected current signal reflecting the DC current output by the fuel cell stack 100 as feedback to perform closed-loop control of the DC current output by the fuel cell stack 100, the control unit 600 can accurately control the DC current output by the fuel cell stack 100, so that the fuel cell system 10 can accurately output the desired power to meet the load's power request. Furthermore, the current command module 610 is also configured to control the converter 510, so that the converter 510 converts the DC power output by the fuel cell stack 100 into DC power suitable for supplying to the battery 520 and the inverter 700. For example, the DC voltage level output by the fuel cell stack 100 may be low, insufficient to charge the battery 520 or drive the traction motor 800. Therefore, the converter 510 is needed to boost the DC voltage output by the fuel cell stack 100 to a level sufficient to charge the battery 520 and drive the traction motor 800. Specifically, when the fuel cell stack 100 cannot meet the power demand of the load, for example, when the electric vehicle 20 is climbing a hill, the current command module 610 is also configured to control the converter 510 in this situation to adjust the electrical energy from the fuel cell stack 100 and the battery 520 and supply it to the inverter 700, thereby utilizing the electrical energy generated by the fuel cell stack 100 and the electrical energy stored in the battery 520 to meet the power demand of the traction motor 800.It is worth noting that, although in the description of this disclosure, the converter 510, battery 520, and control unit 600 are respectively constituted by the DC / DC converter, power battery, and electronic control unit of the electric vehicle 20, this is merely exemplary. In other embodiments, the converter 510, battery 520, and control unit 600 may also be separate devices independent of the DC / DC converter, power battery, and electronic control unit. In summary, the fuel cell system according to this disclosure enables the electric vehicle to accurately assess the humidity within the fuel cell stack to improve the reliability of the fuel cell system, and to accurately control the fuel cell stack to meet the power demands of the load.

[0035] The foregoing has described in detail, with reference to the accompanying drawings, alternative but non-limiting embodiments of the fuel cell system and electric vehicle according to the present disclosure. Modifications and additions to the technology and structure, as well as recombinations of features in the various embodiments, will be readily apparent to those skilled in the art without departing from the spirit and essence of the present disclosure and should be considered as being within the scope of this disclosure. Therefore, such modifications and additions conceivable under the teachings of this disclosure should be considered part of this disclosure. The scope of this disclosure includes equivalent technologies known at the filing date of this disclosure and equivalent technologies not yet foreseen.

Claims

1. A fuel cell system, characterized in that, include: A fuel cell stack (100) configured to output current through a power supply circuit (120); An impedance detection unit (500) includes a converter (510) electrically connected to the power supply circuit (120), a battery (520) electrically connected to the converter (510), and a current sensor (530) disposed on the power supply circuit (120); and The control unit (600) includes a current command module (610) signal-connected to the converter (510) and a current correction module (630) signal-connected to the current command module (610) and the current sensor (530). The current command module (610) is configured to control the converter (510) to convert electrical energy from the battery (520) into AC current input to the fuel cell stack (100) through the power supply circuit (120) according to the AC current waveform. The current correction module (630) is configured to determine a correction current signal based on the current signal measured by the current sensor (530) and a target current signal selected from the AC current waveform.

2. The fuel cell system according to claim 1, characterized in that, The impedance detection unit (500) further includes a voltage sensor (540) disposed on the power supply circuit (120), and the control unit (600) further includes an impedance calculation module (620) connected to the current sensor (530) and the voltage sensor (540) for signal connection. The impedance calculation module (620) is configured to calculate the impedance of the stack (100) based on the current signal measured by the current sensor (530) and the voltage signal measured by the voltage sensor (540).

3. The fuel cell system according to claim 1, characterized in that, It also includes a cathode gas supply unit (200) configured to supply cathode gas to the fuel cell stack (100), an anode gas supply unit (300) configured to supply anode gas to the fuel cell stack (100), and a thermal management unit (400) configured to regulate the temperature within the fuel cell stack (100).

4. The fuel cell system according to any one of claims 1-3, characterized in that, The current correction module (630) is configured to use the difference between the current signal measured by the current sensor (530) and the target current signal as the corrected current signal.

5. The fuel cell system according to claim 4, characterized in that, The current correction module (630) is configured to select a point before a delay time from the AC current waveform as the target current signal.

6. The fuel cell system according to claim 5, characterized in that, The control unit (600) is configured to use the corrected current signal as a feedback signal to perform closed-loop control of the current output by the fuel cell stack (100).

7. An electric vehicle, characterized in that, include: The fuel cell system according to any one of claims 1-6; A DC / DC converter is electrically connected to the power supply circuit (120) of the fuel cell system and is configured to receive current output from the fuel cell stack (100) of the fuel cell system through the power supply circuit (120); An electronic control unit is connected to the current correction module (630) of the fuel cell system and is configured to use the corrected current signal determined by the current correction module (630) as a feedback signal to perform closed-loop control on the current output by the stack (100). as well as A power battery, which is electrically connected to the DC / DC converter, and the DC / DC converter is configured to convert electrical energy from the stack (100) into electrical energy suitable for supplying to the power battery.

8. The electric vehicle according to claim 7, characterized in that, It also includes an inverter (700) electrically connected to the DC / DC converter and a traction motor (800) electrically connected to the inverter (700), the DC / DC converter being configured to convert electrical energy from the fuel cell stack (100) into electrical energy suitable for supplying to the inverter (700).

9. The electric vehicle according to claim 7 or 8, characterized in that, The DC / DC converter, the power battery, and the electronic control unit respectively constitute the converter (510), the battery (520), and the control unit (600) of the fuel cell system.

10. The electric vehicle according to claim 9, characterized in that, The current command module (610) of the control unit (600) is signal-connected to the current correction module (630) and configured to use the corrected current signal as a feedback signal to perform closed-loop control on the current output by the fuel cell stack (100).

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