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JP-7856436-B2 - Fuel cell system and its power control method

JP7856436B2JP 7856436 B2JP7856436 B2JP 7856436B2JP-7856436-B2

Inventors

  • ソン セ フン
  • キム ヤン ファン
  • チョイ ジャエ スン

Assignees

  • 現代自動車株式会社
  • 起亞株式会社

Dates

Publication Date
20260511
Application Date
20220119
Priority Date
20211028

Claims (20)

  1. A first converter that converts power output from a fuel cell stack or battery to a predetermined level of power, A second converter that converts the power input to or output to the aforementioned battery, A power relay assembly that controls the flow of power between a supercapacitor and the first converter, A controller that controls the outputs of the first converter and the second converter and controls the operation of the power relay assembly in accordance with the starting or operating state of the fuel cell system , The first converter is, A fuel cell system characterized in that , when the fuel cell system is started, the charging power supplied from the second converter is supplied to the supercapacitor via the power relay assembly .
  2. The first converter is, It is located at the end of the main bus connecting the fuel cell stack and the inverter, The second converter is, The fuel cell system according to claim 1, characterized in that one end is connected to the main bus terminal between the fuel cell stack and the first converter, and the other end is connected to the battery, thereby regulating the bidirectional flow of power.
  3. The second converter is The fuel cell system according to claim 2, characterized in that, when the fuel cell system is started, the power discharged by the battery is used to supply the starting power of the fuel cell system and the charging power of the supercapacitor.
  4. The aforementioned power relay assembly is The fuel cell system according to claim 1, characterized in that, before receiving charging power via the first converter, the voltage between the output terminal of the first converter and the supercapacitor is adjusted using a precharge relay, and when charging power is supplied via the first converter, the charging power is provided to the supercapacitor using a main relay .
  5. The controller is, The fuel cell system according to claim 3, characterized in that, when the fuel cell system is started, the first converter is driven in constant current mode and the second converter is driven in constant voltage mode.
  6. The controller is, The fuel cell system according to claim 3, characterized in that, when starting the fuel cell system, the starting voltage of the fuel cell stack is set to the output voltage of the second converter, and the limit current of the second converter or the discharge allowable current of the battery is set to the limit current of the second converter.
  7. The controller is, The fuel cell system according to claim 3, characterized in that, when the fuel cell system is started, the charging voltage of the supercapacitor is set to the output voltage of the first converter, the value obtained by subtracting the required current of the auxiliary equipment from the dischargeable current of the battery is set to the output current of the first converter, and the limit current of the first converter or the allowable charging current of the supercapacitor is set to the limit current of the first converter.
  8. The second converter is, During operation of the fuel cell system, the power discharged by the battery is adjusted and output. The first converter is The fuel cell system according to claim 2, characterized in that, during operation of the fuel cell system, the power output via at least one of the fuel cell stack and the second converter is adjusted and supplied to the inverter.
  9. The controller is, The fuel cell system according to claim 8 , characterized in that, during operation of the fuel cell system, the first converter is driven in constant current mode and the second converter is driven in constant voltage mode.
  10. The controller is, The fuel cell system according to claim 8, characterized in that, during operation of the fuel cell system, the output voltage of the first converter is set based on the measured voltage of the supercapacitor, the output current of the first converter is set based on the ratio of the combined power requirements of the fuel cell stack and the battery to the measured voltage of the supercapacitor, and the limiting current of the first converter is set based on the limiting current of the first converter.
  11. The controller is, The fuel cell system according to claim 8, characterized in that, during operation of the fuel cell system, the output voltage of the second converter is set based on the target voltage of the fuel cell stack, the output current of the second converter is set based on the ratio of the target power of the battery to the measured voltage, and the limiting current of the second converter is set based on the discharge allowable current of the battery.
  12. The aforementioned power relay assembly is The fuel cell system according to claim 2, characterized in that, during operation of the fuel cell system, the power discharged from the supercapacitor is supplied to the inverter.
  13. The steps include setting the output of a first converter that adjusts the power output from the fuel cell stack or battery according to the starting or operating state of the fuel cell system, and a second converter that adjusts the power input to or output to the battery, A step of controlling the operation of the power relay assembly according to the starting or operating state of the fuel cell system, The process includes the step of controlling the power supply to the fuel cell stack, battery, and supercapacitor in accordance with the outputs of the first and second converters and the operation of the power relay assembly, The step of controlling the power supply is: The first converter, A power control method for a fuel cell system, characterized by including the step of supplying the charging power supplied from the second converter to the supercapacitor via the power relay assembly when the fuel cell system is started .
  14. The step of setting the output is: The steps include setting the starting voltage of the fuel cell stack to the output voltage of the second converter when starting the fuel cell system, A power control method for a fuel cell system according to claim 13 , characterized by comprising the step of setting the limit current of the second converter or the discharge allowable current of the battery to the limit current of the second converter.
  15. The step of setting the output is: The steps include setting the charging voltage of the supercapacitor to the output voltage of the first converter when starting the fuel cell system, The steps include setting the output current of the first converter to a value obtained by subtracting the current required by the auxiliary equipment from the dischargeable current of the battery, A power control method for a fuel cell system according to claim 13 , characterized by comprising the step of setting the limit current of the first converter or the allowable charging current of the supercapacitor to the limit current of the first converter.
  16. The step of controlling the power supply is: The power control method for a fuel cell system according to claim 13 , characterized in that, when the fuel cell system is started, the second converter supplies starting power to the fuel cell system using the power discharged by the battery.
  17. The step of controlling the power supply is: The fuel cell system starts up, and the second converter supplies power to charge the supercapacitor using the power discharged by the battery, A power control method for a fuel cell system according to claim 13 , characterized in that the first converter adjusts the charging power supplied from the second converter and supplies it to the supercapacitor via the power relay assembly.
  18. The step of controlling the power supply is: Before supplying charging power to the supercapacitor, the power relay assembly connected to the supercapacitor adjusts the voltage between the output terminal of the first converter and the supercapacitor using a precharge relay. A power control method for a fuel cell system according to claim 17 , characterized in that when the power relay assembly is supplied with charging power via the first converter, it uses the main relay to provide charging power to the supercapacitor.
  19. The step of setting the output is: During operation of the fuel cell system, the steps include setting the output voltage of the first converter based on the measured voltage of the supercapacitor, The steps include setting the output current of the first converter based on the ratio of the combined power requirements of the fuel cell stack and the battery to the measured voltage of the supercapacitor, A power control method for a fuel cell system according to claim 13 , characterized by comprising the step of setting a limiting current for the first converter based on the limiting current of the first converter.
  20. The step of setting the output is: During operation of the fuel cell system, the steps include setting the output voltage of the second converter based on the target voltage of the fuel cell stack, The steps include setting the output current of the second converter based on the ratio of the target power of the battery to the measured voltage, A power control method for a fuel cell system according to claim 13 , characterized by comprising the step of setting a limiting current for the second converter based on the discharge allowable current of the battery.

Description

This invention relates to a fuel cell system and a method for controlling its power. Fuel cell systems can generate electrical energy using fuel cell stacks. For example, when hydrogen is used as fuel in fuel cell stacks, it can be an alternative solution to global environmental problems, leading to sustained research and development of fuel cell systems. Vehicles equipped with fuel cell systems utilize a fuel cell (which generates electrical energy using hydrogen fuel) as their primary power source, and are fitted with a hybrid powernet that uses a high-voltage battery as an auxiliary power source. This allows for switching between driving modes depending on driving conditions to improve driving efficiency. In recent years, attempts have been made to apply fuel cell systems to vehicles used in industrial settings, such as excavators. In fuel cell systems applied to vehicles used in industrial settings, in addition to fuel cells, batteries and supercapacitors are also used. In this case, the fuel cell, battery, and supercapacitor can be operated in a hybrid configuration, thus increasing power efficiency. However, operating each energy source in a hybrid configuration requires at least three converters in the power network, and since converters are expensive components, this increases costs. This figure shows a fuel cell system according to one embodiment of the present invention.This diagram shows the energy flow during startup of a fuel cell system according to one embodiment of the present invention.This figure shows the operating state of the converter during startup of a fuel cell system according to one embodiment of the present invention.This diagram shows the energy flow during operation of a fuel cell system according to one embodiment of the present invention.This figure shows the operating state of the converter during operation of a fuel cell system according to one embodiment of the present invention.This diagram shows the operation flow for a power control method of a fuel cell system according to one embodiment of the present invention.This diagram shows the operation flow for a power control method of a fuel cell system according to one embodiment of the present invention.This is an illustrative diagram used to illustrate the output setting operation of a converter according to one embodiment of the present invention.This is an illustrative diagram used to illustrate the output setting operation of a converter according to one embodiment of the present invention. Hereinafter, some embodiments of the present invention will be described in detail with reference to illustrative drawings. It should be noted that, in assigning reference numerals to the components in each drawing, the same reference numerals are used for the same components whenever possible, even when they appear in other drawings. Furthermore, in describing embodiments of the present invention, if a specific description of a related known configuration or function is deemed to hinder understanding of the embodiments of the present invention, such detailed description will be omitted. In describing the components of the embodiments of the present invention, terms such as "first," "second," "A," "B," (a), (b), etc., may be used. Such terms are merely for distinguishing a component from other components, and do not limit the nature, order, or sequence of the component. Furthermore, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as those generally understood by a person of ordinary skill in the art to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application. Figure 1 shows a fuel cell system according to one embodiment of the present invention. Referring to Figure 1, a fuel cell system according to one embodiment of the present invention may include a fuel cell stack 110, an inverter 120, a motor 130, auxiliary equipment 140, a battery 150, a supercapacitor 160, a first converter 170, a second converter 180, and a power relay assembly (PRA) 190. The fuel cell system may further include a controller 200 for controlling the power flow of the fuel cell system. The fuel cell stack 110 (or, as it may be referred to as "fuel cell") can be formed into a structure capable of producing electricity through a redox reaction between a fuel (e.g., hydrogen) and an oxidizer (e.g., air). As an example, the fuel cell stack 110 may include a membrane electrode assembly (MEA) with an electrolyte membrane on which hydrogen ions move, and catalytic electrode layers on both sides of the membrane where electrochemical reactions occur; a gas diffusion layer (GDL) that uniformly distributes the reaction gas and transmits the generated electrical energy;