A hydrogen fuel cell system and a hydrogen fuel cell vehicle

Abstract

The application relates to a hydrogen fuel cell system and a hydrogen fuel cell vehicle, and relates to the technical field of power batteries. A specific embodiment of the hydrogen fuel cell system comprises a hydrogen fuel cell stack and a DC / DC conversion circuit, wherein a positive electrode of the hydrogen fuel cell stack is a system output positive electrode of the hydrogen fuel cell system, and an output end of the DC / DC conversion circuit is a system output negative electrode of the hydrogen fuel cell system; a positive input electrode of the DC / DC conversion circuit is electrically connected with the positive electrode of the hydrogen fuel cell stack, and a negative input electrode of the DC / DC conversion circuit is electrically connected with a negative electrode of the hydrogen fuel cell stack; wherein the DC / DC conversion circuit is used for generating a negative voltage. The embodiment reduces the working power of the DC / DC conversion circuit, reduces the cost of the hydrogen fuel cell system, and expands the applicable scenarios of the hydrogen fuel cell.

Description

Technical Field

[0001] This application relates to the field of power battery technology, and in particular to a hydrogen fuel cell system and a hydrogen fuel cell vehicle. Background Technology

[0002] A hydrogen fuel cell system is a non-combustion energy conversion device that converts the chemical energy of hydrogen at the anode and oxygen at the cathode into electrical energy through an electrochemical reaction. To address the characteristics of hydrogen fuel cell systems, such as the need for rapid and significant adjustments in output voltage to accommodate changes in output current, and the requirement for the fuel cell stack's output power (affected by the supply rate of hydrogen and oxygen) to respond quickly to changes in external load power, related technologies first connect the fuel cell stack's output to a DC / DC (Direct Current to Direct Current) converter circuit for voltage adjustment before supplying power to the electrical load.

[0003] The above-mentioned solutions in the relevant technologies require that the operating power of the DC / DC conversion circuit be greater than or equal to the total operating power of the hydrogen fuel cell system while ensuring the normal operation of the electrical load. This increases the layout cost of the DC / DC conversion circuit, as well as the packaging and heat dissipation costs, resulting in a higher total cost of the hydrogen fuel cell system and a narrower application scenario. There is currently no effective solution to the above-mentioned problems in the relevant technologies. Summary of the Invention

[0004] The hydrogen fuel cell system and hydrogen fuel cell vehicle provided by the present invention at least solve the problems of high operating power required by the DC / DC conversion circuit in the hydrogen fuel cell system, high cost of the hydrogen fuel cell system, and narrow application scenarios of the hydrogen fuel cell system in the related art.

[0005] To address the aforementioned problems, one aspect of the present invention provides a hydrogen fuel cell system, including a hydrogen fuel cell stack and a DC / DC conversion circuit, wherein:

[0006] The positive terminal of the hydrogen fuel cell stack is the positive output terminal of the hydrogen fuel cell system, and the output terminal of the DC / DC converter circuit is the negative output terminal of the hydrogen fuel cell system.

[0007] The positive input terminal of the DC / DC converter circuit is electrically connected to the positive terminal of the hydrogen fuel cell stack, and the negative input terminal of the DC / DC converter circuit is electrically connected to the negative terminal of the hydrogen fuel cell stack; wherein, the DC / DC converter circuit is used to generate a negative voltage.

[0008] In some embodiments, the hydrogen fuel cell system further includes an energy storage system, the positive terminal of which is electrically connected to the positive terminal of the hydrogen fuel cell stack, and the negative terminal of which is electrically connected to the output terminal of the DC / DC conversion circuit. The positive terminal of the energy storage system is used as the positive terminal of the system output, and the negative terminal of the energy storage system is used as the negative terminal of the system output.

[0009] In some embodiments, the DC / DC conversion circuit includes a control device, a switching device, an inductor, a diode, and a capacitor; wherein the switching device is located on the positive input bus, the control device is used to control the closing and opening of the switching device, the inductor and the capacitor are connected in parallel, and the diode is located on the positive input bus between the inductor and the capacitor.

[0010] In some embodiments, the control device further includes a sampling module for sampling the system output voltage of the hydrogen fuel cell system and the stack output voltage of the hydrogen fuel cell stack, determining the target voltage value of the negative voltage output by the DC / DC conversion circuit based on the system output voltage value and the stack output voltage value, and controlling the duty cycle of the closed state of the switching device to ensure that the voltage value of the negative voltage output by the DC / DC conversion circuit meets the target voltage value.

[0011] In some of these embodiments, the DC / DC conversion circuit operates at a lower power than the total operating power of the hydrogen fuel cell system.

[0012] To address the aforementioned problems, one aspect of this invention provides a hydrogen fuel cell vehicle, comprising: a hydrogen fuel cell system as described in any of the preceding embodiments.

[0013] The beneficial effects of this invention are as follows: By employing a hydrogen fuel cell system including a hydrogen fuel cell stack and a DC / DC conversion circuit, wherein the positive terminal of the hydrogen fuel cell stack is the positive output terminal of the hydrogen fuel cell system, and the output terminal of the DC / DC conversion circuit is the negative output terminal of the hydrogen fuel cell system; the positive input terminal of the DC / DC conversion circuit is electrically connected to the positive terminal of the hydrogen fuel cell stack, and the negative input terminal of the DC / DC conversion circuit is electrically connected to the negative terminal of the hydrogen fuel cell stack; wherein the technical solution of the DC / DC conversion circuit for generating negative voltage satisfies the characteristics that the system output voltage needs to be rapidly and significantly adjusted with changes in output current during the operation of the hydrogen fuel cell system, and that the supply rate of hydrogen and oxygen needs to respond quickly to changes in the power of the external load, while reducing the operating power of the DC / DC conversion circuit, reducing the cost of the hydrogen fuel cell system, and expanding the applicable scenarios of hydrogen fuel cells.

[0014] Details of one or more embodiments of the present invention are set forth in the following drawings and description, so that other features, objects and advantages of the invention will be more readily understood. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the framework of a hydrogen fuel cell system in related technologies.

[0017] Figure 2 This is a schematic diagram of the framework of a hydrogen fuel cell system according to one embodiment of the present invention.

[0018] Figure 3 This is a schematic diagram of the framework of a hydrogen fuel cell system according to another embodiment of the present invention.

[0019] Figure 4 This is a schematic diagram of the circuit topology of a DC / DC conversion circuit according to one embodiment of the present invention.

[0020] Figure 5 yes Figure 3 The diagram shows the current of each component in the hydrogen fuel cell system. Detailed Implementation

[0021] Embodiments of this embodiment will now be described in more detail with reference to the accompanying drawings. While some embodiments of this embodiment are shown in the drawings, it should be understood that this embodiment can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this embodiment. It should be understood that the accompanying drawings and embodiments are for illustrative purposes only and are not intended to limit the scope of protection of this embodiment.

[0022] During high-current discharge in a hydrogen fuel cell system, the system output voltage decreases as the output current increases. This necessitates that the system output voltage of the hydrogen fuel cell system be able to adjust rapidly and significantly according to changes in the discharge current. Furthermore, since the hydrogen fuel cell system requires a reaction between hydrogen at the anode and oxygen at the cathode, and the hydrogen and oxygen are typically supplied by an external air compressor, the system must also possess the characteristic of rapidly responding to changes in the power of the external load by supplying hydrogen and oxygen to meet the power demands of electrical loads with high power fluctuations. In other words, the output power of the hydrogen fuel cell stack must be able to respond rapidly to changes in the power of the external load.

[0023] To meet the two characteristics required for the operation of a hydrogen fuel cell system, such as Figure 1 As shown, in related technologies, the output of the hydrogen fuel cell stack is connected to a DC / DC converter circuit for voltage regulation (stabilization), and then further stabilized by an energy storage system (such as a supercapacitor or lithium-ion battery) before supplying power to the electrical load. However, when using the above-mentioned scheme in related technologies, since the operating power of the DC / DC converter circuit is determined by the maximum input power, it is necessary to maintain the operating power of the DC / DC converter circuit greater than or equal to the total power of the hydrogen fuel cell system to ensure the normal operation of the electrical load. Furthermore, the cost of the DC / DC converter circuit is proportional to its operating efficiency, resulting in high installation costs for the DC / DC converter circuit in the related technologies, leading to a high overall cost for the hydrogen fuel cell system and a narrow range of application scenarios for hydrogen fuel cells.

[0024] To address the aforementioned problems, embodiments of the present invention provide a hydrogen fuel cell system, such as... Figure 2 As shown, the hydrogen fuel cell system mainly includes: a hydrogen fuel cell stack and a DC / DC conversion circuit. The positive terminal of the hydrogen fuel cell stack is the positive output terminal of the hydrogen fuel cell system, and the output terminal of the DC / DC conversion circuit is the negative output terminal of the hydrogen fuel cell system. The positive input terminal of the DC / DC conversion circuit is electrically connected to the positive terminal of the hydrogen fuel cell stack, and the negative input terminal of the DC / DC conversion circuit is electrically connected to the negative terminal of the hydrogen fuel cell stack. The DC / DC conversion circuit is used to generate a negative voltage.

[0025] The hydrogen fuel cell stack provided in this embodiment of the invention refers to a device that uses the electrochemical reaction of hydrogen and oxygen to generate electrical energy, a technology known to those skilled in the art.

[0026] This invention, through adjusting the connection between the hydrogen fuel cell stack and the DC / DC conversion circuit, specifically by electrically connecting the positive and negative input terminals of the DC / DC conversion circuit to the positive and negative terminals of the hydrogen fuel cell stack, respectively, uses the positive terminal of the hydrogen fuel cell stack as the system output positive terminal of the hydrogen fuel cell system and the output terminal of the DC / DC conversion circuit as the output negative terminal of the hydrogen fuel cell system. Compared to related technologies (directly connecting the positive and negative terminals of the hydrogen fuel cell stack to the positive and negative terminals of the DC / DC conversion circuit, so that the output voltage of the hydrogen fuel cell stack is adjusted by the DC / DC conversion circuit and used as the output voltage of the hydrogen fuel system), the system output voltage of the hydrogen fuel cell system provided by this invention can respond to changes in discharge current efficiently and significantly, increasing the voltage regulation range of the DC / DC conversion circuit while reducing the operating power required by the DC / DC conversion circuit, thus reducing the cost of the hydrogen fuel cell system and expanding the applicable scenarios of hydrogen fuel cells.

[0027] In some embodiments, the hydrogen fuel cell system further includes an energy storage system, the positive electrode of which is electrically connected to the positive electrode of the hydrogen fuel cell stack, the negative electrode of which is electrically connected to the output terminal of the DC / DC conversion circuit, and the positive electrode of the energy storage system is used as the positive output electrode of the system, and the negative electrode of the energy storage system is used as the negative output electrode of the system.

[0028] The above embodiments provide an extended solution to the embodiments of the present invention, such as... Figure 3 As shown, an energy storage system is introduced into the hydrogen fuel cell system. The positive electrode of the hydrogen fuel cell is electrically connected to the positive electrode of the energy storage system, and the output of the DC / DC conversion circuit is electrically connected to the negative electrode of the energy storage system to provide energy to the energy storage system. The energy storage system then supplies power to external loads. On the one hand, the energy storage system can respond to the power changes of the external load in real time, improving the user experience. On the other hand, it can store the extra energy output by the hydrogen fuel cell system as an emergency energy source, which helps to further expand the application scenarios of the hydrogen fuel cell system.

[0029] In some embodiments, the DC / DC conversion circuit includes a control device, a switching device, an inductor, a diode, and a capacitor; wherein the switching device is located on the positive input bus, the control device is used to control the closing and opening of the switching device, the inductor and the capacitor are connected in parallel, and the diode is located on the positive input bus between the inductor and the capacitor.

[0030] like Figure 4 As shown, in the DC / DC conversion circuit provided in this embodiment of the invention, an inductor and a capacitor are connected in parallel between the positive bus and the negative bus, and a switching device is provided on the input positive bus. The closing and opening of the switching device is controlled by a control device. At the same time, a diode is provided on the input positive bus between the capacitor and the inductor connected in parallel.

[0031] In some embodiments, the control device further includes a sampling module for sampling the system output voltage of the hydrogen fuel cell system and the stack output voltage of the hydrogen fuel cell stack, determining the target voltage value of the negative voltage output by the DC / DC conversion circuit based on the system output voltage value and the stack output voltage value, and controlling the duty cycle of the closed state of the switching device to ensure that the voltage value of the negative voltage output by the DC / DC conversion circuit meets the target voltage value.

[0032] In some embodiments of the present invention, the control device determines the target voltage value output by the DC / DC conversion circuit by sampling the system output voltage value and the stack output voltage value, and then achieves the output of the target voltage value by controlling the duty cycle of the closing time period of the switching device relative to the opening time period. For example... Figure 4As shown, U1 is the positive voltage at the input terminal of the DC / DC converter circuit, and U2 is the negative voltage at the output terminal of the DC / DC converter circuit. The control device controls the amplitude of the negative voltage at the output terminal by controlling the duty cycle of the switching device's closing and closing. For example, if the positive voltage at the DC / DC input terminal is 100V, the negative voltage at the DC / DC output terminal can be controlled to be -100V, then the system output voltage is 200V. Since the non-isolated positive voltage DC / DC converter circuit and the non-isolated negative voltage DC / DC converter circuit use the same components in the circuit topology, under the same power, the cost required by the non-isolated negative voltage DC / DC converter circuit of this embodiment is the same as that of the non-isolated positive voltage DC / DC converter circuit in the related art, but the expansion of the system output voltage amplitude is significantly increased.

[0033] According to a specific embodiment of the present invention, such as Figure 3 As shown, U3 is the output voltage of the hydrogen fuel cell stack, U4 is the negative voltage output of the DC / DC converter circuit, and U5 is the system output voltage of the hydrogen fuel cell system. According to Kirchhoff's voltage law, U5 = U3 - U4. When the stack output voltage U3 = 100V, if the negative voltage U4 output by the DC / DC converter is controlled to -100V, the final system output voltage U5 = U3 - U4 = 200V. Therefore, by controlling the negative voltage U4 output by the DC / DC converter circuit, the system output voltage U5 can be controlled.

[0034] In some of these embodiments, the operating power of the aforementioned DC / DC conversion circuit is lower than the total operating power of the hydrogen fuel cell system.

[0035] According to a specific embodiment of the present invention, such as Figure 5As shown, assuming the maximum output power of the hydrogen fuel cell system is 70kW, when the stack output voltage of the hydrogen fuel cell stack drops from 100V under no-load conditions to 70V, the stack output current is I1 = 1000A. Since the voltage of the electrical load needs to be stabilized at 200V, the negative voltage value (i.e., the target voltage value) of the negative voltage DC / DC converter circuit needs to be adjusted to -130V. This ensures that the system output voltage of the hydrogen fuel cell system remains stable at 200V. Based on the load power of 70kW, the load current can be calculated as I3 = 350A. According to Kirchhoff's current law, the input current of the negative voltage DC / DC converter circuit at this time is I2 = 650A. Therefore, the input power of the negative voltage DC / DC converter circuit at this time is 70V * 650A = 45.5kW; the output power of the negative voltage DC / DC converter circuit at this time is 350A * 130V = 45.5kW. Assuming a 100% conversion efficiency for the negative voltage DC / DC converter circuit, the input power of the negative voltage DC / DC converter circuit equals its output power. In a 70kW hydrogen fuel cell system, only a 45.5kW negative voltage DC / DC converter circuit is needed to meet the requirements. At this point, the power of the negative voltage DC / DC converter circuit is 65% of the system's rated power. That is, by adopting the hydrogen fuel cell system provided in this embodiment of the invention, the required operating power of the DC / DC converter circuit is reduced. The operating power of the DC / DC converter circuit is lower than the total operating power of the hydrogen fuel cell system, reducing the layout cost of the DC / DC converter circuit and thus lowering the cost of the hydrogen fuel cell system.

[0036] The hydrogen fuel cell system provided in this embodiment of the invention employs a hydrogen fuel cell stack and a DC / DC conversion circuit. The positive terminal of the hydrogen fuel cell stack is the positive output terminal of the hydrogen fuel cell system, and the output terminal of the DC / DC conversion circuit is the negative output terminal. The positive input terminal of the DC / DC conversion circuit is electrically connected to the positive terminal of the hydrogen fuel cell stack, and the negative input terminal is electrically connected to the negative terminal of the hydrogen fuel cell stack. The technical solution for generating a negative voltage in the DC / DC conversion circuit satisfies the characteristics of the hydrogen fuel cell system requiring rapid and significant adjustment of the system output voltage with changes in output current during operation, and the requirement for a high-speed response of hydrogen and oxygen supply to changes in the power of the external load. Simultaneously, it reduces the operating power of the DC / DC conversion circuit, lowers the cost of the hydrogen fuel cell system, and expands the applicable scenarios for hydrogen fuel cells.

[0037] Based on the hydrogen fuel cell system provided in the embodiments of the present invention, the present invention also provides a hydrogen fuel cell vehicle, wherein the hydrogen fuel cell vehicle is equipped with any of the above-mentioned hydrogen fuel cell systems.

[0038] It should be noted that the term "comprising" and its variations used in the embodiments of the present invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The modifications of "one" and "multiple" mentioned in the embodiments of the present invention are illustrative and not restrictive. Those skilled in the art should understand that, unless explicitly indicated otherwise in the context, they should be understood as "one or more".

[0039] The steps described in the method embodiments provided by this invention can be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of protection of this invention is not limited in this respect.

[0040] The term "embodiment" in this specification refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of the invention. The appearance of this phrase in various places in the specification does not necessarily imply the same embodiment, nor does it imply independence or alternativeity from other embodiments. The various embodiments in this specification are described in a related manner, with reference to each other for similar or identical parts. In particular, for apparatus, device, and system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, and relevant details are referred to in the description of the method embodiments.

[0041] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A hydrogen fuel cell system, characterized in that, Includes hydrogen fuel cell stacks and DC / DC conversion circuits, among which: The positive terminal of the hydrogen fuel cell stack is the positive output terminal of the hydrogen fuel cell system, and the output terminal of the DC / DC conversion circuit is the negative output terminal of the hydrogen fuel cell system. The positive input terminal of the DC / DC conversion circuit is electrically connected to the positive terminal of the hydrogen fuel cell stack, and the negative input terminal of the DC / DC conversion circuit is electrically connected to the negative terminal of the hydrogen fuel cell stack; wherein, the DC / DC conversion circuit is used to generate a negative voltage; the DC / DC conversion circuit includes a control device, a switching device, an inductor, a diode, and a capacitor; wherein, the switching device is located on the positive input bus, the control device is used to control the closing and opening of the switching device, the inductor and the capacitor are connected in parallel, and the diode is located on the positive input bus between the inductor and the capacitor; The operating power of the DC / DC conversion circuit is lower than the total operating power of the hydrogen fuel cell system.

2. The hydrogen fuel cell system according to claim 1, characterized in that, The hydrogen fuel cell system also includes an energy storage system. The positive electrode of the energy storage system is electrically connected to the positive electrode of the hydrogen fuel cell stack, and the negative electrode of the energy storage system is electrically connected to the output terminal of the DC / DC conversion circuit. The positive electrode of the energy storage system is used as the positive electrode of the system output, and the negative electrode of the energy storage system is used as the negative electrode of the system output.

3. The hydrogen fuel cell system according to claim 1, characterized in that, The control device further includes a sampling module for sampling the system output voltage value of the hydrogen fuel cell system and the stack output voltage value of the hydrogen fuel cell stack, determining the target voltage value of the negative voltage output by the DC / DC conversion circuit based on the system output voltage value and the stack output voltage value, and controlling the duty cycle of the closed state of the switching device to ensure that the voltage value of the negative voltage output by the DC / DC conversion circuit meets the target voltage value.

4. A hydrogen fuel cell vehicle, characterized in that, include: The hydrogen fuel cell system as described in any one of claims 1-3.

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