Method and apparatus for heating a fuel cell stack

Abstract

The application provides a heating method and device for a fuel cell stack, and belongs to the technical field of fuel cells, and solves the problem that the prior art cannot low-power, fast and accurate cold start of a fuel cell. The method comprises the following steps: winding an energized coil on the inner wall surface of the stack PACK and fixing; identifying the low-temperature cold start of the fuel cell, starting the cooling liquid small circulation loop, and introducing fuel gas into the stack to start the fuel cell; obtaining the temperature of the cooling liquid entering the stack, determining the difference between the stack cooling liquid temperature and the target temperature; identifying that the difference is higher than the set value, selecting a frequency in the high alternating current frequency range for the power supply of the energized coil to quickly heat the stack; identifying that the difference is not higher than the set value, selecting a frequency in the low alternating current frequency range for the power supply of the energized coil to slowly heat the stack to prevent temperature overshoot; until the stack cooling liquid temperature reaches the target temperature, the above power supply is ended. The method can realize fast and accurate temperature control.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a heating method and apparatus for a fuel cell stack. Background Technology

[0002] The electrochemical reactions within a fuel cell need to occur at a specific temperature. During a cold start-up at low temperatures, low-temperature fuel cells require rapid heating to prevent water from forming and freezing. Similarly, high-temperature fuel cells also require rapid heating during startup to reduce startup time.

[0003] Currently, common heating methods for fuel cells include hydrogen-oxygen combustion heating, electric heating, and hydrogen pump heating. Hydrogen-oxygen combustion heating requires an additional burner, increasing system complexity and posing safety risks. Electric heating indirectly heats the gas or coolant through resistance wires, transferring heat into the fuel cell stack; however, it suffers from lag, high energy consumption, and low thermal efficiency. Hydrogen pump heating utilizes oxygen starvation, converting some hydrogen protons into hydrogen gas at the cathode, which then reacts with oxygen to release heat. However, it suffers from uneven temperature distribution and slow heating rate, making it particularly unsuitable for heating high-temperature fuel cells during startup.

[0004] Existing patents CN202111060717.1 and CN201910417503.1 disclose a heating method for eddy current heating. This method avoids direct contact between hydrogen and AC coil, enabling non-contact heating and rapid heating. However, it cannot achieve precise temperature control and is prone to temperature overshoot. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a heating method and apparatus for a fuel cell stack, in order to solve the problem that the prior art cannot perform fuel cell cold start with low power consumption, fast and accurate operation.

[0006] On one hand, embodiments of the present invention provide a heating method for a fuel cell stack, comprising the following steps:

[0007] The energized coil is wound around the inner wall surface of the battery pack and secured.

[0008] When a fuel cell is identified to be in a low-temperature cold start, the coolant circulation loop of the fuel cell is started, and fuel gas is introduced into the stack to start the fuel cell.

[0009] Obtain the temperature of the fuel cell stack coolant and determine the difference between the fuel cell stack coolant temperature and the target temperature;

[0010] The following temperature control is performed based on the difference between the fuel cell coolant temperature and the target temperature: when the difference is higher than the set value, a frequency is selected within the high AC frequency range of 400-1000Hz to power the energizing coil for rapid heating of the fuel cell; when the difference is not higher than the set value, a frequency is selected within the low AC frequency range of 10-300Hz to power the energizing coil for slow heating of the fuel cell to prevent temperature overshoot; during the slow heating process, the power supply is terminated when the fuel cell coolant temperature reaches the target temperature.

[0011] The beneficial effects of the above technical solution are as follows: Based on Faraday's law of electromagnetic induction, a high-frequency alternating current passing through an induction coil generates an alternating magnetic field. The metal component generates an induced electromotive force in this alternating magnetic field, forming eddy currents. Subsequently, due to the Joule effect, Joule heat is generated inside the metal, resulting in rapid heating with almost no heat loss. The mechanism is similar to that of an induction cooker. Heating is achieved through the metal bipolar plates or metal support within the fuel cell stack, significantly shortening the heating time and improving heating efficiency. Furthermore, it offers advantages such as adjustable heating temperature, a wide heating temperature range, and relatively uniform heating.

[0012] Based on the above method, an improvement is made: when the difference is higher than a set value, the step of performing temperature control according to the difference between the fuel cell coolant temperature and the target temperature further includes:

[0013] A frequency is selected within the high AC frequency range of 400 to 1000 Hz to power the energized coil, so as to rapidly heat the fuel cell stack.

[0014] During rapid heating, the temperature of the coolant fed into the stack is acquired periodically. When the difference between the coolant temperature and the target temperature is not higher than the set value, the power supply frequency of the energizing coil is switched to an AC frequency within 10 to 300 Hz to slowly heat the stack.

[0015] During the slow heating process, the temperature of the coolant fed into the reactor continues to be monitored in real time. Once the temperature of the coolant fed into the reactor reaches the target temperature, the power supply to the energized coil is cut off to prevent temperature overshoot.

[0016] Furthermore, when the difference is less than or equal to a set value, the step of performing the following temperature control based on the difference between the fuel cell coolant temperature and the target temperature further includes:

[0017] A frequency is selected within the low AC frequency range of 10 to 300 Hz to power the energized coil, so as to slowly heat the fuel cell stack.

[0018] During the slow heating process, the temperature of the coolant fed into the reactor is monitored in real time. Once the temperature of the coolant fed into the reactor reaches the target temperature, the power supply to the energized coil is cut off to prevent temperature overshoot.

[0019] Furthermore, when the difference is higher than the set value, the step of performing the following temperature control based on the difference between the fuel cell coolant temperature and the target temperature further includes:

[0020] The difference between the temperature of the coolant entering the reactor and the target temperature, and the target temperature are used as inputs to a pre-trained high-frequency artificial neural network model to obtain the rated AC frequency and rated number of coil turns that minimize heating time, power consumption, and frequency range of 400 to 1000 Hz.

[0021] Increase the number of coil turns of the energized coil to the above-mentioned rated number of coil turns, and supply power to the energized coil at the above-mentioned rated AC frequency to rapidly heat the fuel cell stack;

[0022] During rapid heating, the temperature of the coolant fed into the stack is acquired periodically. When the difference between the coolant temperature and the target temperature is not higher than the set value, the power supply frequency of the energizing coil is switched to a fixed AC frequency within the range of 20Hz to 300Hz to slowly heat the stack.

[0023] During the slow heating process, the temperature of the coolant fed into the reactor is monitored in real time. Once the temperature of the coolant fed into the reactor reaches the target temperature, the power supply to the energized coil is cut off to prevent temperature overshoot.

[0024] Furthermore, when the difference is less than or equal to a set value, the step of performing the following temperature control based on the difference between the fuel cell coolant temperature and the target temperature further includes:

[0025] The difference between the temperature of the coolant entering the reactor and the target temperature, and the target temperature are used as inputs to a pre-trained low-frequency artificial neural network model to obtain the rated AC frequency and rated number of coil turns in the range of 20Hz to 300Hz that minimizes heating time and power consumption.

[0026] Reduce the number of turns of the energized coil to the above-mentioned rated number of turns, and supply power to the energized coil at the above-mentioned rated AC frequency to slowly heat the fuel cell stack;

[0027] During the slow heating process, the temperature of the coolant fed into the reactor is monitored in real time. Once the temperature of the coolant fed into the reactor reaches the target temperature, the power supply to the energized coil is cut off to prevent temperature overshoot.

[0028] Furthermore, the set value is 10-15℃.

[0029] Furthermore, this method is applicable to fuel cells with bipolar plates made of metallic materials, or high-temperature inorganic membrane fuel cells with a support made of metallic materials.

[0030] Furthermore, inside the battery pack, an insulating layer and a heat insulation layer are provided between the energized coil and the battery pack; among them,

[0031] An insulating layer is used to prevent electrical conductivity between the metal components and the energized coils within the fuel cell stack.

[0032] The heat insulation layer is used to maintain a stable temperature of the coolant inside the fuel cell stack.

[0033] Furthermore, the heating method also includes:

[0034] An electric heater is installed in the small circulation loop of the fuel cell's coolant.

[0035] When the difference between the stack coolant temperature and the target temperature is higher than the set value, the electric heater is also activated to rapidly heat the stack through the electric heater and the eddy current heating of the energized coil.

[0036] When the difference between the stack coolant temperature and the target temperature is not higher than the set value, the electric heater is turned off, and the stack is slowly heated only through the eddy currents of the energized coil.

[0037] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0038] 1. By utilizing the electromagnetic induction heating mechanism, heat is generated through the metal bipolar plates or metal support itself, which can significantly shorten the heating time of fuel cells, improve heating efficiency, and has the advantages of adjustable heating temperature, wide heating temperature range, and relatively uniform heating.

[0039] 2. It can be used in conjunction with an electric heater to accelerate the heating rate.

[0040] 3. The heat generation rate can be adjusted (in direct proportion) by the number of coil turns and the alternating current frequency, where the alternating current can be achieved through an inverter. The heating temperature is adjustable and can be controlled in a closed-loop manner using a thermocouple sensor.

[0041] On the other hand, embodiments of the present invention also provide a heating device for a fuel cell stack, including an energized coil, an inverter, a thermocouple sensor, and a heating controller; wherein,

[0042] The energized coil is wound around the inner wall surface of the battery pack and fixed in place;

[0043] An inverter is used to convert input direct current into alternating current with an adjustable frequency to power a coil.

[0044] Thermocouple sensors are placed on the inner wall of the coolant inlet pipe of the fuel cell stack and connected to the heating controller to obtain the temperature of the fuel cell stack coolant.

[0045] A heating controller is used to monitor the coolant temperature of the fuel cell stack in real time; and, when the difference between the coolant temperature and the target temperature is higher than a set value, to select a frequency in the high AC frequency range of 400 to 1000 Hz to power the energizing coil for rapid heating of the fuel cell stack; and, when the difference is not higher than the set value, to select a frequency in the low AC frequency range of 10 to 300 Hz to power the energizing coil for slow heating of the fuel cell stack to prevent temperature overshoot; and, during the slow heating process, to identify that the coolant temperature of the fuel cell stack has reached the target temperature and terminate the power supply.

[0046] The summary section is provided to present the chosen concepts in a simplified form, which will be further described in the detailed description below. The summary section is not intended to identify essential or essential features of the invention, nor is it intended to limit the scope of the invention. Attached Figure Description

[0047] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same parts.

[0048] Figure 1 A schematic diagram of the heating method steps for the fuel cell stack in Example 1 is shown;

[0049] Figure 2 A schematic diagram of the winding method of the energized coil in the heating method of the fuel cell stack of Example 1 is shown;

[0050] Figure 3 A schematic diagram of eddy currents inside the metal bipolar plate or metal support body of the fuel cell stack in Embodiment 1 is shown.

[0051] Figure 4 A schematic diagram of the temperature control process in Example 2 is shown.

[0052] Figure label:

[0053] 1-Electrified coil; DC-DC-DC-DC converter; DC / AC-DC / AC converter;

[0054] 2-Bipolar plate or support; 3-Coil interface; 4-PACK contains stacked fuel cell units; T target -Target temperature; T 入 - Temperature of the coolant added to the reactor. Detailed Implementation

[0055] Embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0056] The term "comprising" and its variations as used herein signify open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0057] Example 1

[0058] One embodiment of the present invention discloses a heating method for a fuel cell stack, such as... Figure 1 As shown, it includes the following steps:

[0059] S1. Wrap the energized coil around the inner wall surface of the battery pack and secure it;

[0060] Specifically, the energized coil can be wound in a serpentine manner and fixed to the inner wall surface of the fuel cell stack PACK using clips or adhesive; the fuel cell stack PACK contains stacked fuel cell units 4, and the bipolar plates or supports 2 of the fuel cell units are generally made of metal; the control scheme for the energized coil is as follows: Figure 2 As shown, the frequency of AC power can be adjusted by an inverter, and the current can be converted into frequency-controllable AC power by DC-DC and DC / AC.

[0061] S2. When the fuel cell is detected to be in a low-temperature cold start, start the small circulation loop of the coolant in the fuel cell and introduce fuel gas into the stack to start the fuel cell;

[0062] Specifically, the coolant loop of a fuel cell refers to the coolant loop that does not pass through the radiator. After it is started, it can make the fuel cell (coolant) heat up evenly.

[0063] S3. Obtain the temperature of the fuel cell stack coolant and determine the difference between the fuel cell stack coolant temperature and the target temperature;

[0064] S4. Based on the difference between the fuel cell coolant temperature and the target temperature, perform the following temperature control: when the difference is higher than the set value, select a frequency within the high AC frequency range of 400-1000Hz to power the energizing coil to quickly heat the fuel cell; when the difference is not higher than the set value, select a frequency within the low AC frequency range of 10-300Hz to power the energizing coil to slowly heat the fuel cell and prevent temperature overshoot; during the slow heating process, when the fuel cell coolant temperature reaches the target temperature, end the above power supply.

[0065] In practice, by connecting alternating current to the energized coil, the direction of the current constantly changes, causing the metal bipolar plate or metal support to cut magnetic field lines in the magnetic field, thereby generating eddy currents inside the bipolar plate or support. Figure 3 As shown. According to Joule's law, current flowing through a conductor generates a large amount of heat due to the resistance, which can rapidly heat the fuel cell stack.

[0066] After the fuel cell is started (fuel gas or air is introduced), if the stack coolant temperature (T) is detected... 出 Less than the target temperature (T) target If the difference between the target temperature and the actual temperature is higher than the set value (10℃), then a larger AC frequency (400Hz~10kHz) is selected for rapid heating. If the difference is within the set value (10℃), then a lower AC frequency (10~300Hz) is selected for slow heating to prevent temperature overshoot. Finally, after the actual temperature (fuel cell coolant temperature) reaches the target temperature, the eddy current heating is turned off.

[0067] In practice, existing technologies heat too rapidly near the target temperature, creating a time lag between heating and sensor feedback. Due to the lag in temperature rise caused by the coolant and the stack's heat capacity, this leads to temperature overshoot, exceeding the target temperature and damaging the membrane electrode assembly (MEA). However, the fuel cell using the solution described in this embodiment, after rapid heating, can switch to a low AC frequency range of 10–300 Hz for slow heating. Extensive testing has verified that this significantly improves temperature control and effectively prevents temperature overshoot.

[0068] Compared with existing technologies, the heating method provided in this embodiment is based on Faraday's law of electromagnetic induction. A high-frequency alternating current passing through an induction coil generates an alternating magnetic field. The metal component generates an induced electromotive force in this field, forming eddy currents. Subsequently, due to the Joule effect, Joule heat is generated within the metal, offering advantages such as rapid heating and almost no heat loss. The mechanism is similar to that of an induction cooker. Heating is achieved through the metal bipolar plates or metal support within the fuel cell stack, significantly shortening the fuel cell heating time and improving heating efficiency. Furthermore, it offers advantages such as adjustable heating temperature, a wide heating temperature range, and relatively uniform heating.

[0069] Example 2

[0070] Based on Example 1, this heating method is improved by incorporating an electric heater for rapid temperature control, and further includes the following steps:

[0071] S0. Install an electric heater in the small circulation loop of the fuel cell coolant;

[0072] S4*. Based on the difference between the stack coolant temperature and the target temperature, perform the following temperature control: When the difference is higher than the set value, start the electric heater and select a frequency within the high AC frequency range of 400-1000Hz to power the energized coil, so as to quickly heat the stack through the electric heater and the eddy current heating of the energized coil; when the difference is not higher than the set value, turn off the electric heater and select a frequency within the low AC frequency range of 10-300Hz to power the energized coil, so as to slowly heat the stack only through the eddy current heating of the energized coil to prevent temperature overshoot; when the stack coolant temperature reaches the target temperature during the slow heating process, end the above power supply.

[0073] Optionally, the control method can achieve temperature regulation solely through AC frequency, and when the difference is higher than the set value, step S4 further includes:

[0074] S41. Select a frequency within the high AC frequency range of 400 to 1000 Hz to power the energized coil so as to rapidly heat the fuel cell stack;

[0075] S42. During rapid heating, the temperature of the coolant fed into the stack is acquired periodically. When the difference between the temperature of the coolant fed into the stack and the target temperature is not higher than the set value, the power supply frequency of the energizing coil is switched to an AC frequency within 10 to 300 Hz to slowly heat the stack.

[0076] S43. During the slow heating process, the temperature of the coolant fed into the reactor is monitored in real time. Once the temperature of the coolant fed into the reactor reaches the target temperature, the power supply to the energized coil is cut off to prevent temperature overshoot.

[0077] When the difference is less than or equal to a set value, step S4 further includes:

[0078] S41'. Select a frequency within the low AC frequency range of 10 to 300 Hz to power the energized coil, so as to slowly heat the fuel cell stack;

[0079] S42'. During the slow heating process, the temperature of the coolant fed into the reactor is monitored in real time. Once the temperature of the coolant fed into the reactor reaches the target temperature, the power supply to the energized coil is cut off to prevent temperature overshoot.

[0080] Optionally, the control method can also achieve temperature regulation by combining the AC frequency with the number of coil turns. When the difference is higher than the set value, step S4 further includes:

[0081] S41#. The difference between the temperature of the coolant entering the reactor and the target temperature, and the target temperature are used as inputs. The pre-trained high-frequency artificial neural network model is then used to obtain the rated AC frequency and rated number of coil turns that minimize heating time, power consumption, and frequency range of 400 to 1000 Hz.

[0082] S42#. Increase the number of coil turns of the energizing coil to the above-mentioned rated number of coil turns, and supply power to the energizing coil at the above-mentioned rated AC frequency to rapidly heat the fuel cell stack;

[0083] S43#. During rapid heating, the temperature of the coolant entering the stack is acquired periodically. When the difference between the coolant temperature entering the stack and the target temperature is not higher than the set value, the power supply frequency of the energizing coil is switched to a fixed AC frequency within 20Hz to 300Hz to slowly heat the stack.

[0084] S44#. During the slow heating process, the temperature of the coolant fed into the reactor is monitored in real time. Once the temperature of the coolant fed into the reactor reaches the target temperature, the power supply to the energized coil is cut off to prevent temperature overshoot.

[0085] When the difference is less than or equal to a set value, step S4 further includes:

[0086] S41#'. The difference between the temperature of the coolant entering the reactor and the target temperature, and the target temperature are used as inputs. The pre-trained artificial neural network low-frequency model is then input to obtain the rated AC frequency and rated number of coil turns in the frequency range of 20Hz to 300Hz that minimizes heating time and power consumption.

[0087] S42#'. Reduce the number of coil turns of the energizing coil to the above-mentioned rated number of coil turns, and supply power to the energizing coil at the above-mentioned rated AC frequency to slowly heat the fuel cell stack;

[0088] S43#'. During the slow heating process, the temperature of the coolant fed into the reactor is monitored in real time. Once the temperature of the coolant fed into the reactor reaches the target temperature, the power supply to the energized coil is cut off to prevent temperature overshoot.

[0089] Preferably, the set value is 10℃, and the principle is as follows: Figure 4 As shown.

[0090] Preferably, this method is particularly applicable to fuel cells with bipolar plates made of metal materials, or high-temperature inorganic membrane fuel cells with a support made of metal materials.

[0091] Preferably, an insulating layer and a heat insulation layer are provided inside the battery pack between the energized coil and the battery pack. The insulating layer prevents electrical conductivity between the metal components inside the battery pack and the energized coil. The heat insulation layer maintains a stable temperature of the coolant inside the battery pack.

[0092] Compared with the prior art, the heating method of this embodiment has the following beneficial effects:

[0093] 1. By utilizing the electromagnetic induction heating mechanism, heat is generated through the metal bipolar plates or metal support itself, which can significantly shorten the heating time of the fuel cell, improve the heating efficiency, and the heating temperature is adjustable, has a wide range of heating temperature, and is relatively uniform in heating.

[0094] 2. It can be used in conjunction with an electric heater to accelerate the heating rate.

[0095] 3. The heat generation rate can be adjusted (in direct proportion) by the number of coil turns and the alternating current frequency, where the alternating current can be achieved through an inverter. The heating temperature is adjustable and can be controlled in a closed-loop manner using a thermocouple sensor.

[0096] Example 3

[0097] The present invention also discloses a heating device using the method described in Embodiment 1 or 2 above, comprising an energized coil, an inverter, a thermocouple sensor, and a heating controller.

[0098] The energized coil is wound around the inner wall surface of the battery pack and fixed in place.

[0099] An inverter is used to convert input direct current into alternating current with an adjustable frequency to power a coil.

[0100] Thermocouple sensors are placed on the inner wall of the coolant inlet pipe of the fuel cell stack and connected to the heating controller to obtain the temperature of the fuel cell stack coolant.

[0101] A heating controller is used to monitor the coolant temperature of the fuel cell stack in real time; and, when the difference between the coolant temperature and the target temperature is higher than a set value, to select a frequency in the high AC frequency range of 400Hz to 10kHz to supply power to the energizing coil to rapidly heat the fuel cell stack; and, when the difference is not higher than the set value, to select a frequency in the low AC frequency range of 10 to 300Hz to supply power to the energizing coil to slowly heat the fuel cell stack to prevent temperature overshoot; and, during the slow heating process, to identify that the coolant temperature of the fuel cell stack has reached the target temperature and terminate the above power supply.

[0102] Preferably, the heating device further includes an adjustment mechanism for adjusting the number of turns of the regulating coil. For example, multiple sets of coils can be set, and in use, a rated number of coil sets can be activated according to the input requirements.

[0103] Preferably, an insulating layer and a heat insulation layer are provided inside the battery pack between the energized coil and the battery pack. The insulating layer prevents electrical conductivity between the metal components inside the battery pack and the energized coil. The heat insulation layer maintains a stable temperature of the coolant inside the battery pack.

[0104] Preferably, the heating device further includes a DC-DC converter and a DC / AC converter connected in sequence, with the inverter integrated at the DC / AC stage to convert the current into frequency-controllable alternating current.

[0105] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or improvements to the prior art of the embodiments, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A heating method for a fuel cell stack, characterized in that, Includes the following steps: The energized coil is wound around the inner wall surface of the battery pack and secured. When a fuel cell is identified to be in a low-temperature cold start, the coolant circulation loop of the fuel cell is started, and fuel gas is introduced into the stack to start the fuel cell. Obtain the temperature of the fuel cell stack coolant and determine the difference between the fuel cell stack coolant temperature and the target temperature; The following temperature control is performed based on the difference between the fuel cell coolant temperature and the target temperature: when the difference is higher than a set value, a frequency is selected within the high AC frequency range of 400~1000 Hz to power the energizing coil for rapid heating of the fuel cell; when the difference is not higher than the set value, a frequency is selected within the low AC frequency range of 20~300 Hz to power the energizing coil for slow heating of the fuel cell to prevent temperature overshoot; during the slow heating process, the power supply is terminated when the fuel cell coolant temperature reaches the target temperature. When the difference is higher than the set value, the step of performing the following temperature control based on the difference between the fuel cell coolant temperature and the target temperature further includes: The difference between the temperature of the coolant entering the reactor and the target temperature, and the target temperature are used as inputs to a pre-trained high-frequency artificial neural network model to obtain the rated AC frequency and rated number of coil turns that minimize heating time, power consumption, and frequency range of 400~1000 Hz. Increase the number of coil turns of the energized coil to the above-mentioned rated number of coil turns, and supply power to the energized coil at the above-mentioned rated AC frequency to rapidly heat the fuel cell stack; During rapid heating, the temperature of the coolant entering the stack is acquired periodically. When the difference between the coolant temperature entering the stack and the target temperature is not higher than the set value, the power supply frequency of the energizing coil is switched to a fixed AC frequency within 20Hz~300Hz to slowly heat the stack. During the slow heating process, the temperature of the coolant fed into the reactor is monitored in real time. Once the temperature of the coolant fed into the reactor reaches the target temperature, the power supply to the energized coil is cut off to prevent temperature overshoot.

2. The heating method for a fuel cell stack according to claim 1, characterized in that, When the difference is not higher than the set value, the step of performing the following temperature control based on the difference between the fuel cell coolant temperature and the target temperature further includes: The difference between the temperature of the coolant entering the reactor and the target temperature, and the target temperature are used as inputs to a pre-trained low-frequency artificial neural network model to obtain the rated AC frequency and rated number of coil turns within the frequency range of 20Hz to 300Hz that minimizes heating time and power consumption. Reduce the number of turns of the energized coil to the above-mentioned rated number of turns, and supply power to the energized coil at the above-mentioned rated AC frequency to slowly heat the fuel cell stack; During the slow heating process, the temperature of the coolant fed into the reactor continues to be monitored in real time. Once the temperature of the coolant fed into the reactor reaches the target temperature, the power supply to the energized coil is cut off to prevent temperature overshoot.

3. The heating method for a fuel cell stack according to claim 2, characterized in that, The set value is 10~15℃.

4. The heating method for a fuel cell stack according to claim 3, characterized in that, This method is applicable to fuel cells with bipolar plates made of metallic materials, or high-temperature inorganic membrane fuel cells with a support made of metallic materials.

5. The heating method for a fuel cell stack according to any one of claims 1, 3, and 4, characterized in that, Inside the fuel cell stack (PACK), there are insulating and heat-insulating layers between the energized coils and the stack; among them, An insulating layer is used to prevent electrical conductivity between the metal components and the energized coils within the fuel cell stack. The heat insulation layer is used to maintain a stable temperature of the coolant inside the fuel cell stack.

6. The heating method for a fuel cell stack according to any one of claims 1, 3, and 4, characterized in that, Also includes: An electric heater is installed in the small circulation loop of the fuel cell's coolant. When the difference between the temperature of the coolant entering the stack and the target temperature is higher than the set value, the electric heater is also activated to rapidly heat the stack through the electric heater and the eddy current heating of the energized coil. When the difference between the coolant temperature and the target temperature is not higher than the set value, the electric heater is turned off, and the fuel cell stack is slowly heated only through the eddy currents of the energized coil.

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