Low-temperature cold purging control method for fuel cell system

Abstract

The invention relates to the field of purging control methods, in particular to a low-temperature cold purging control method for a fuel cell system. The purging control method comprises the following steps: S1, after a fuel cell system enters a low-temperature shutdown state, firstly purging a fuel cell, and removing water on the fuel cell through purging; s2, after purging is finished, when the outlet temperature T of the fuel cell is higher than the temperature T1, the fuel cell does not enter a second-stage state; and when the outlet temperature T of the fuel cell is less than or equal to the temperature T1, entering a second-stage state. The cold purging time in the low-temperature cold start process can be shortened, and the use friendliness of a user is improved; the cold blowing broom proton exchange membrane can be effectively prevented from being blown too dry in the low-temperature cold start process, and the service life of a fuel cell system is prolonged; by means of the mode that the high-frequency impedance value of the final target cold start temperature is obtained through non-direct purging, the consumption of hydrogen can be effectively reduced, and the economical efficiency of fuel is improved.

Description

Technical Field

[0001] The present invention relates to the field of purge control methods, in particular to a low-temperature cold purge control method for a fuel cell system. Background Art

[0002] As a vehicle power source, fuel cells must withstand complex operating conditions and harsh environments such as start-stop, cold start (or sub-zero start), high potential, voltage cycle, high current, and air impurities. Among them, cold start is the main obstacle to the commercialization of proton exchange membrane fuel cells. During the sub-zero temperature start-up process of the proton exchange membrane fuel cell, the water generated by the reaction will freeze inside the fuel cell, covering the surface of the catalyst layer, reducing the electrochemical active area, affecting the performance of the fuel cell, and even causing startup failure. In order to ensure the working performance of the fuel cell, it is necessary to quickly increase the temperature of the fuel cell through the cold start method to reach the working temperature of the fuel cell (60℃~80℃), so that the fuel cell can be more widely used in actual production.

[0003] The current low-temperature cold start control method is to enter the cold purge state and directly purge to the high-frequency impedance value of the final target cold start temperature. Although it can ensure that the reaction product water is blown away, there is a risk of blowing the fuel cell proton exchange membrane too dry due to the purge time, which affects the service life of the fuel cell system. At the same time, directly purging to the high-frequency impedance value corresponding to the final target cold start temperature will increase the corresponding hydrogen consumption and the use cost of the fuel cell system. Summary of the invention

[0004] In order to overcome the shortcoming of the existing purge technology that the purge time is too long, the present invention provides a low-temperature cold purge control method for a fuel cell system.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a low-temperature cold purge control method for a fuel cell system, comprising the following steps: S1. When the fuel cell system enters the low-temperature shutdown state, the fuel cell is first purged to remove water on the fuel cell; S2. After the purge is completed, if the outlet temperature T of the fuel cell is greater than temperature T1, the second stage state will not be entered; if the outlet temperature T of the fuel cell is less than or equal to temperature T1, the second stage state will be entered; S3, after entering the second stage state, continue to monitor the outlet temperature T of the fuel cell. Of course, when the outlet temperature T of the fuel cell is greater than temperature T2, purge is performed until the outlet temperature T of the fuel cell is less than or equal to temperature T2, then enter the third stage state; S4, after entering the third stage state, continue to monitor the outlet temperature T of the fuel cell. Of course, when the outlet temperature T of the fuel cell is greater than temperature T3, purge until the outlet temperature T of the fuel cell is less than or equal to temperature T3, then enter the fourth stage state; S5, when the fuel cell meets the conditions, the purge is terminated; Temperature T1<Temperature T2<Temperature T3<Temperature T4.

[0006] According to another embodiment of the present invention, the temperature T1, temperature T2, temperature T3, and temperature T4 further include a range of -35°C to 0°C.

[0007] According to another embodiment of the present invention, the outlet temperature T of the fuel cell is further obtained by a temperature sensor, and the temperature sensor is electrically connected to the PLC.

[0008] According to another embodiment of the present invention, the purging is further implemented by an air press, and the air press is electrically connected to the PLC.

[0009] According to another embodiment of the present invention, the temperature sensor further detects the temperature of the outlet of the fuel cell after a time interval of X.

[0010] According to another embodiment of the present invention, the end condition of the purge is further comprised of the fuel cell being able to start up the corresponding high frequency impedance value at temperature T1, temperature T2, temperature T3 or temperature T4.

[0011] The beneficial effects of the present invention are that the invention can reduce the time of cold purge during low-temperature cold start, thereby improving user-friendliness; it can effectively prevent the cold purge during low-temperature cold start from blowing the proton exchange membrane too dry, thereby improving the service life of the fuel cell system; the method of non-directly purging to the high-frequency impedance value of the final target cold start temperature can effectively reduce the consumption of hydrogen and improve the economy of fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0013] Figure 1 is a flow chart of the present invention; DETAILED DESCRIPTION

[0014] Figure 1 It is a flow chart of the present invention.

[0015] As attached Figure 1 As shown, a fuel cell system low temperature cold purge control method comprises the following steps: S1. When the fuel cell system enters the low-temperature shutdown state, the fuel cell is first purged to remove water on the fuel cell; this state corresponds to the end time of the purge, which is determined by the high-frequency impedance value that can be started at the sub-zero temperature T1.

[0016] S2. After the purge is completed, if the outlet temperature T of the fuel cell is greater than temperature T1, the second stage state will not be entered; if the outlet temperature T of the fuel cell is less than or equal to temperature T1, the second stage state will be entered; this state corresponds to the time when the purge is completed, which is determined by the high-frequency impedance value that can be started at the sub-zero temperature T2.

[0017] S3, after entering the second stage state, continue to monitor the outlet temperature T of the fuel cell. Of course, purge when the outlet temperature T of the fuel cell is greater than temperature T2, until the outlet temperature T of the fuel cell is less than or equal to temperature T2, then enter the third stage state; this state corresponds to the time when the purge ends, which is determined by the corresponding high-frequency impedance value that can be started at the sub-zero temperature T3.

[0018] S4, after entering the third stage state, continue to monitor the outlet temperature T of the fuel cell. Of course, when the outlet temperature T of the fuel cell is greater than temperature T3, purge is performed until the outlet temperature T of the fuel cell is less than or equal to temperature T3, then enter the fourth stage state; this state corresponds to the time when the purge ends, which is determined by the corresponding high-frequency impedance value that can be started at the sub-zero temperature T4.

[0019] S5. When the fuel cell meets the conditions, the purge is terminated.

[0020] Temperature T1<Temperature T2<Temperature T3<Temperature T4.

[0021] The ranges of temperature T1, temperature T2, temperature T3 and temperature T4 are -35°C to 0°C.

[0022] The outlet temperature T of the fuel cell is obtained by a temperature sensor, and the temperature sensor is electrically connected to the PLC.

[0023] The blowing is realized by the air compressor, which is electrically connected to the PLC. The PLC obtains the temperature information uploaded by the temperature sensor and automatically controls the start and stop of the air compressor.

[0024] The temperature sensor detects the temperature of the outlet of the fuel cell after a time interval of X.

[0025] The end condition of the purge is that the fuel cell can start the corresponding high-frequency impedance value at the temperature T1, the temperature T2, the temperature T3 or the temperature T4.

Claims

1. A low temperature cold purge control method for a fuel cell system, characterized in that: The following steps are involved: S1. When the fuel cell system enters the low-temperature shutdown state, the fuel cell is first purged to remove water on the fuel cell; S2. After the purge is completed, if the outlet temperature T of the fuel cell is greater than temperature T1, the second stage state will not be entered; if the outlet temperature T of the fuel cell is less than or equal to temperature T1, the second stage state will be entered; S3, after entering the second stage state, continue to monitor the outlet temperature T of the fuel cell. Of course, when the outlet temperature T of the fuel cell is greater than temperature T2, purge is performed until the outlet temperature T of the fuel cell is less than or equal to temperature T2, then enter the third stage state; S4, after entering the third stage state, continue to monitor the outlet temperature T of the fuel cell. Of course, when the outlet temperature T of the fuel cell is greater than temperature T3, purge until the outlet temperature T of the fuel cell is less than or equal to temperature T3, then enter the fourth stage state; S5, when the fuel cell meets the conditions, the purge is terminated; Temperature T1<Temperature T2<Temperature T3<Temperature T4.

2. The low temperature cold purge control method for a fuel cell system according to claim 1, characterized in that: The temperature T1, temperature T2, temperature T3 and temperature T4 range from -35°C to 0°C.

3. The low temperature cold purge control method for a fuel cell system according to claim 1, characterized in that: The outlet temperature T of the fuel cell is obtained by a temperature sensor, and the temperature sensor is electrically connected to the PLC.

4. The low temperature cold purge control method for a fuel cell system according to claim 3, characterized in that: The purging is achieved by an air compressor, which is electrically connected to the PLC.

5. The low temperature cold purge control method of a fuel cell system according to claim 3, characterized in that: The temperature sensor detects the temperature of the outlet of the fuel cell after a time interval of X.

6. The low temperature cold purge control method of a fuel cell system according to claim 1, characterized in that: The end condition of the purge is that the fuel cell can start the corresponding high-frequency impedance value at temperature T1, temperature T2, temperature T3 or temperature T4.

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