Air-cooled fuel cell power system and control method

Abstract

The application discloses a forced air cooling type fuel cell power system and a control method, and the voltage value, the current value, the real-time power, the temperature value, the online internal resistance and the corresponding time value of a fuel cell subsystem are acquired, and the corresponding current-target temperature curve, the current-standard internal resistance curve and the current-voltage-power curve are constructed, the target temperature value, the online internal resistance and the standard voltage value are calculated in real time, the critical voltage of the heat dissipation fan, the exhaust valve and the auxiliary battery is controlled, and the operation efficiency and the service life of the fuel cell are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cell, in particular to a wind-cooled fuel cell power system and a control method. BACKGROUND

[0002] Fuel cells directly convert fuel chemical energy into electrical energy, have high energy conversion efficiency, low noise, zero emissions and other advantages, are ideal mobile power sources, and have wide application prospects in the fields of automobiles, unmanned aerial vehicles, ships, electronic products and the like. The wind-cooled fuel cell power system has the advantages of simple system and easy control, and is particularly suitable for small power scenarios.

[0003] The existing wind-cooled fuel cell power system mainly has the following problems: 1. The output performance of the fuel cell is sensitive to temperature and humidity conditions, and the relative fixed temperature control strategy is not adaptive to different temperatures, so that the fuel cell cannot be kept in the best working state; 2. A liquid water discharge valve is needed in the fuel cell to discharge liquid water, however, frequent opening of the discharge valve will increase hydrogen consumption, and conversely, delayed opening of the discharge valve will cause water to be unable to be discharged in time and block the hydrogen transmission channel, thereby reducing the output voltage and even causing damage to the membrane electrode; 3. When the fuel cell system is at a high temperature for a long time and is short of hydrogen for a long time, the membrane electrode will accelerate to decay, thereby affecting the service life; 4. The fuel cell has performance degradation during the service life, and under the condition that the total power supply of the power system is unchanged, the fuel cell is prone to overload and accelerate performance decay.

[0004] Obviously, the control strategy has a great influence on the performance and service life of the fuel cell, and for example, Chinese Invention CN115483420A discloses a control method of a wind-cooled fuel cell, which controls the speed of a fan to dissipate heat from the fuel cell, and uses an electric heater to assist in heating the electric pile, so that the fuel cell operates in an efficient temperature range. However, this control strategy only considers the influence of temperature on operating efficiency, and does not comprehensively consider operating efficiency and service life. SUMMARY

[0005] In view of the above problems, the present application provides a wind-cooled fuel cell power system and a control method, which aims to improve the adaptability of the fuel cell to the environment and the service life of the power system.

[0006] To solve the above technical problems, the present application provides a wind-cooled fuel cell power system in the first aspect, which comprises a fuel cell subsystem, an auxiliary battery, and a controller coupled with the fuel cell subsystem and the auxiliary battery, respectively, and the fuel cell subsystem at least comprises:

[0007] a fuel cell stack, an exhaust valve installed at the outlet end of the fuel cell stack, a heat dissipation fan for cooling the fuel cell stack, and a temperature sensor for acquiring the surface temperature of the fuel cell stack.

[0008] The signal output end of the temperature sensor and the output end of the fuel cell stack are connected to the controller.

[0009] The second aspect of the present application provides a control method for the air-cooled fuel cell power system, comprising the following steps:

[0010] The opening interval of the exhaust valve is defined as the effective data acquisition time, in which the controller acquires the voltage and current values of the fuel cell stack output, the temperature value output by the temperature sensor, and the acquisition time;

[0011] The product of the voltage value and the current value is defined as the real-time power, and the absolute value of the ratio of the voltage difference and the current difference corresponding to the minimum current value and the maximum current value in a unit time is defined as the online internal resistance;

[0012] The voltage value, the current value, the real-time power, the temperature value, the online internal resistance, and the corresponding time value are classified into a database, and the data in the database is divided into short-term data and long-term data according to a first preset condition;

[0013] Based on the short-term data, a preset number of characteristic current values are selected from the current values, and the voltage value, the current value, the online internal resistance, and the real-time power that meet a second preset condition are respectively screened based on the characteristic current values, and current-target temperature curves, current-standard internal resistance curves, and current-voltage-power curves are respectively fitted and generated;

[0014] According to the current-target temperature curve, the corresponding target temperature value under the current current value is found, and the controller adjusts the rotation speed of the cooling fan to control the temperature value within the range of the target temperature value;

[0015] According to the current-standard internal resistance curve, the standard internal resistance under the current current is found, and if the negative deviation of the online internal resistance from the standard internal resistance exceeds a preset range, the exhaust valve is opened once;

[0016] According to the current-voltage-power curve, the standard voltage value under the rated intervention power is found, and the standard voltage value is set as the charge-discharge critical voltage of the auxiliary battery.

[0017] In some embodiments, the first preset condition includes: classifying the data in the time (t-2t cycle ) to (t-t cycle ) as the short-term data, and classifying the data in the time 0 to t as the long-term data, wherein t is the total running time of the fuel cell stack, and t cycle is the update period of the short-term data.

[0018] In some embodiments, the second preset condition comprises: defining the current value as the current within the range of ±1% of the reference current; defining the peak voltage and the corresponding temperature at the current value as the voltage value and the temperature value; defining the valley value of the online resistance value at the current value as the online resistance; and defining the average power value at the current value as the real-time power value.

[0019] In some embodiments, the characteristic current value is selected from the current value corresponding to the voltage within 0.9-0.5V of the single fuel cell, and the number N of the selected characteristic current values is greater than 3. I In some embodiments, the number N of the selected characteristic current values is greater than 3.

[0020] In some embodiments, based on the short-term data, if the temperature value continuously exceeds the target temperature value within a period of time, the controller issues an alarm to prompt that the temperature is too high.

[0021] In some embodiments, based on the short-term data, if the online resistance continuously exceeds the standard resistance within a preset time range, the controller issues an alarm to prompt that the online resistance is too high.

[0022] In some embodiments, based on the long-term data, the characteristic current value of 0.6V voltage of a single piece is selected from the current value as a reference, the time value and the real-time power value that meet the third preset condition are screened respectively, a time-power curve is generated by fitting, and the real-time controller predicts the allowed service life of the fuel cell subsystem according to the time-power curve.

[0023] In some embodiments, the third preset condition comprises: the current value is within the range of ±1% of the reference current, and the time value and the real-time power value are the running time t and the real-time power at the current value.

[0024] The present application has the following beneficial effects: by obtaining the voltage value, current value, real-time power, temperature value, online resistance of the fuel cell subsystem, and the corresponding time value, the corresponding current-target temperature curve, current-standard resistance curve and current-voltage-power curve are constructed respectively, the target temperature value, online resistance and standard voltage value are calculated in real time, the critical voltage of the heat dissipation fan, exhaust valve and auxiliary battery is controlled, and the operating efficiency and service life of the fuel cell are improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The schematic diagram of the air-cooled fuel cell power system disclosed in Embodiment One of the present application is shown in the figure;

[0026] Figure 2 The schematic diagram of the fuel cell subsystem disclosed in Embodiment One of the present application is shown in the figure;

[0027] Figure 3 Flow chart of the control method disclosed in Embodiment Two of the present application;

[0028] Figure 4 Adjustment diagram of the auxiliary battery charge-discharge critical voltage value disclosed in Embodiment Two of the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present application more clear and explicit, the content of the present application will be further described in detail below in combination with the drawings and specific embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, in order to facilitate the description, only the parts related to the present application are shown in the drawings, but not all the contents.

[0030] Embodiment One

[0031] The present embodiment proposes a forced air cooling type fuel cell power system, as shown in the figure, which comprises a fuel cell subsystem 1, an auxiliary battery 2, and a controller 3 coupled with the fuel cell subsystem 1 and the auxiliary battery 2 respectively. Since the power output performance of the fuel cell subsystem 1 and the auxiliary battery 2 is different, in order to achieve higher efficient and stable total power output, the output ends of the fuel cell subsystem 1 and the auxiliary battery 2 are coupled with the controller 3 respectively, and the controller 3 outputs electric power to a load 4 and supplies power to the controller 3. The auxiliary battery 2 can be discharged, or charged by the fuel cell subsystem 1. Figure 1 As shown in the figure, the fuel cell subsystem 1 at least comprises:

[0032] Figure 2 A fuel cell stack 11, an exhaust valve 14 installed at the outlet end of the fuel cell stack 11, the controller 3 supplies power to the exhaust valve 14 and controls the opening and closing of the exhaust valve 14. It also includes a cooling fan 12 for cooling the fuel cell stack 11, in addition, the fuel cell stack 11 is wrapped with an outer shell 19, the cooling fan 12 is aligned with the outer shell 19, the controller 3 supplies power to the cooling fan 12 and adjusts the rotating speed of the cooling fan 12 to control the temperature at a target value, and a temperature sensor 13 for obtaining the surface temperature of the fuel cell stack 11, measuring the temperature inside the fuel cell subsystem 1; the signal output end of the temperature sensor 13 and the output end of the fuel cell stack 11 are connected to the controller 3. Among them, the fuel cell stack 11 is connected with the exhaust valve 14 through a hydrogen outlet pipeline 16, and connected with an oxygen cylinder 17 through a hydrogen inlet pipeline 15, the output end of the oxygen cylinder 17 is provided with a gas pressure sensor 18 for obtaining the output pressure of the oxygen cylinder 17. The controller 3 further comprises a voltage sensor, a current sensor and a memory (not shown in the figure).

[0033]

[0034] ​​Embodiment two

[0035] The embodiment proposes a control method for the air-cooled fuel cell power system described in embodiment one, which can effectively improve the net power density of the fuel cell stack, the hydrogen utilization rate, and ensure the stable and safe output of the entire power system.

[0036] As Figure 3 described, comprising the following steps:

[0037] Step one, define the opening interval of the exhaust valve as the effective data collection time, and in the effective data collection time, the controller collects the voltage value and current value of the fuel cell stack output, the temperature value of the temperature sensor output, and the collection time.

[0038] Step two, in a unit time, the product of the voltage value and the current value is defined as the real-time power, and the absolute value of the ratio of the voltage difference and the current difference corresponding to the lowest current value and the highest current value is defined as the online resistance.

[0039] Step three, the voltage value, current value, real-time power, temperature value, online resistance (Δ voltage / Δ current), and corresponding time value are classified into a database, and the data in the database is divided into short-term data and long-term data according to the first preset condition.

[0040] The first preset condition includes: dividing the data in the time (t-2t cycle ) to (t-t cycle ) into short-term data, and dividing the data in 0 to t time into long-term data, wherein t is the total running time of the fuel cell stack, and t cycle is the update period of the short-term data. The time t is the time recorded since the fuel cell is assembled, and is also the current time value of the fuel cell operation, indicating the duration of the fuel cell operation. It will not be cleared with the short-term update period.

[0041] Step four, based on the short-term data, select a preset number of characteristic current values from the current values, and based on the characteristic current values, respectively select the voltage values, current values, online resistances, and real-time powers that meet the second preset condition, and respectively fit to generate the current-target temperature curve, the current-standard resistance curve, and the current-voltage-power curve.

[0042] The characteristic current value selects the current value corresponding to the voltage of 0.9-0.5V of a single fuel cell, and the number N I of selected characteristic current values is greater than 3. The second preset condition includes: defining the current within the range of ±1% of the reference current as the current value; defining the peak voltage and the corresponding temperature under the current value as the voltage value and the temperature value; defining the valley value of the online resistance value under the current value as the online resistance; and defining the average power under the current value as the real-time power value.

[0043] Step five, find the target temperature value corresponding to the current current value according to the current-target temperature curve, and the controller 3 adjusts the speed of the cooling fan 12 to control the temperature value within the target temperature value.

[0044] In step five, select N I characteristic current high output voltage data points, fit the "current-target temperature curve", and the voltage value is the modified voltage considering the cooling fan power consumption. The controller 3 finds the target temperature value of the current current according to the "current-target temperature curve", and the controller adjusts the speed of the cooling fan to control the temperature to the target temperature value.

[0045] Step six, find the standard resistance of the current current according to the current-standard resistance curve, and if the negative deviation of the current online resistance from the standard resistance exceeds the preset range, the exhaust valve is opened once.

[0046] In step six, select N I characteristic current low online resistance data points, fit the "current-standard resistance curve", and the controller 3 finds the standard resistance value of the current current according to the "current-standard resistance curve". If the negative deviation of the current online resistance from the standard resistance exceeds a certain range, such as 20%, the exhaust valve 14 is opened once.

[0047] Step seven, find the standard voltage value at the rated intervention power according to the current-voltage-power curve, and set the standard voltage value as the charge and discharge threshold voltage of the auxiliary battery.

[0048] In step seven, select N I characteristic current voltage value to fit the "current-voltage, power curve", and the controller finds the standard voltage value at the hover power according to the "current-voltage, power curve". Continue to refer to Figure 2 , the terminal voltage value of the fuel cell subsystem 1 is voltage A, and the terminal voltage value of the auxiliary battery 2 is voltage B. The fuel cell subsystem 1 converts the voltage to voltage C through the controller and connects it with the auxiliary battery 2. When voltage C < voltage B, the auxiliary battery 2 is in discharge mode, and when voltage C > voltage B, the auxiliary battery 2 is in charge mode. Therefore, voltage C is the charge and discharge threshold voltage of the auxiliary battery 2. The fuel voltage A will decrease in performance after long-term use of the fuel cell, and its output voltage will decrease at the same hover power. Voltage C must be adjusted to match the auxiliary battery 2 with the fuel cell subsystem 1. As Figure 4 shown, find the voltage value V corresponding to the hover power PHover according to the "current-voltage, power curve", and set this value as the voltage C as the charge and discharge threshold voltage of the auxiliary battery, to ensure stable and safe output of the entire power system.

[0049] Step eight, based on short-term data, if the temperature value is continuously higher than the target temperature value within a period of time, the controller issues an alarm prompt for high temperature.

[0050] Step nine, based on short-term data, if the online resistance is continuously higher than the standard resistance within a preset time range, the controller issues an alarm prompt for high online resistance.

[0051] Step ten, based on long-term data, the characteristic current value of single chip 0.6V voltage is selected from the current value as a reference, and the time value and real-time power that meet the third preset condition are screened respectively, and a time-power curve is generated by fitting, and the real-time controller predicts the allowed service life of the fuel cell subsystem according to the time-power curve.

[0052] The third preset condition includes: the current value is the current value within ±1% of the reference current, and the time value and real-time power value are the running time t and real-time power under the current value.

[0053] The above steps five to ten have no specific order, and the user can select and set according to actual needs.

[0054] The beneficial effects of the present embodiment include:

[0055] 1. The memory can record the operating parameters of the fuel cell power system online to form a database.

[0056] 2. The "current-target temperature curve" is used for temperature control threshold optimization, so that the fuel cell works under the best temperature condition, and the system efficiency is improved.

[0057] 3. The "current-standard resistance curve" is used for exhaust valve opening and closing strategy optimization, which identifies the increase of internal resistance caused by insufficient hydrogen in the stack, avoids frequent opening of the exhaust valve, and improves hydrogen utilization rate.

[0058] 4. The "current-voltage-power curve" is used for energy management optimization, which changes the auxiliary battery charging voltage in time when the performance of the fuel cell decreases, to ensure the stability and endurance of the power system.

[0059] 5. The "time-power curve" is used for fuel cell system life prediction to ensure system safety and stability.

[0060] 6. The controller can identify the fault condition of over-temperature and high internal resistance, and issue an alarm prompt to avoid long-term operation of the system in the fault condition.

[0061] The above examples are only for the purpose of illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the essence of the present application should be covered within the protection scope of the present application.

Claims

1. A method of controlling an air-cooled fuel cell power system for an air-cooled fuel cell power system comprising a fuel cell subsystem, an auxiliary battery, and a controller coupled to the fuel cell subsystem and the auxiliary battery, respectively, the fuel cell subsystem comprising at least: The fuel cell stack, the exhaust valve installed at the outlet end of the fuel cell stack, the heat dissipation fan for cooling the fuel cell stack, and the temperature sensor for obtaining the surface temperature of the fuel cell stack, characterized in that it comprises the following steps: The opening interval of the exhaust valve is defined as the effective data acquisition time, and the controller acquires the voltage and current values of the fuel cell stack output, the temperature value output by the temperature sensor, and the acquisition time during the effective data acquisition time; The product of the voltage value and the current value is defined as the real-time power, and the absolute value of the ratio of the voltage difference and the current difference corresponding to the minimum current value and the maximum current value in a unit time is defined as the online resistance; The voltage value, the current value, the real-time power, the temperature value, the online resistance, and the corresponding time value are classified into short-term data and long-term data in the database according to the first preset condition; Based on the short-term data, a preset number of characteristic current values are selected from the current values, and the voltage value, the current value, the online resistance, and the real-time power that meet the second preset condition are selected respectively based on the characteristic current values, and the current-target temperature curve, the current-standard resistance curve, and the current-voltage-power curve are fitted respectively; According to the current-target temperature curve, the target temperature value corresponding to the current current value is found, and the controller adjusts the speed of the heat dissipation fan to control the temperature value within the range of the target temperature value; According to the current-standard resistance curve, the standard resistance under the current current is found, and if the negative deviation of the online resistance from the standard resistance exceeds the preset range, the exhaust valve is opened once; According to the current-voltage-power curve, the standard voltage value under the rated intervention power is found, and the standard voltage value is set as the charge and discharge critical voltage of the auxiliary battery.

2. The control method according to claim 1, characterized by, The first preset condition includes: dividing data in (0, T1) into the short-term data, and dividing data in (0, T2) into the long-term data, wherein T1 t -2 t cycle ) into the short-term data, and dividing data in (0, T2) into the long-term data, wherein T1 t - t cycle ) into the short-term data, and dividing data in (0, T2) into the long-term data, wherein T1 t T2. t is the collection time of the fuel cell stack, t cycle is the update period of the short-term data.

3. The control method according to claim 1, characterized by, The second preset condition includes: defining the current within the range of ±1% of the reference current as the current value; defining the peak voltage under the current value and the corresponding temperature as the voltage value and the temperature value; defining the valley value of the online resistance value under the current value as the online resistance; and defining the average power value under the current value as the real-time power value.

4. The control method according to claim 1, characterized by, The characteristic current value is selected from current values corresponding to voltages in the range of 0.9-0.5 V of a single fuel cell, and the number of selected characteristic current values is N I greater than 3.

5. The control method according to claim 1, characterized by, Based on the short-term data, if the temperature value is continuously higher than the target temperature value for a period of time, the controller issues an alarm prompt for high temperature.

6. The control method according to claim 1, characterized by, Based on the short-term data, if the online resistance is continuously higher than the standard resistance within a preset time range, the controller issues an alarm prompt for high online resistance.

7. The control method according to claim 1, characterized by, Based on the long-term data, the characteristic current value of single piece 0.6V voltage is selected from the current values as the reference, and the time value and the real-time power that meet the third preset condition are selected respectively, and the time-power curve is fitted to predict the allowed service life of the fuel cell subsystem by the real-time controller according to the time-power curve.

8. The control method according to claim 7, characterized by, The third preset condition comprises: the current value is a current value within a range of ±1% of a reference current, and the time value and real-time power value are time and real-time power under the current value. t and real-time power.

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