Single valve water and nitrogen venting control method and system for a fuel cell system

Abstract

This invention discloses a single-valve drainage and nitrogen removal control method and system for a fuel cell system. The single-valve drainage and nitrogen removal control method includes: after the drainage valve is closed in the previous cycle, acquiring the current and running time under different operating conditions in real time, and controlling the water production rate S. a =f(I), thus obtaining the water production rate S a Then the water volume W a =ΣS a *ΔT; based on the pressure difference P across the gas-water separator, f(P) = f(t), and water volume W a The actual total operating time T after the water in the storage chamber is completely drained is obtained. x1 According to T x =T x1 +αT a The first total opening time T of the drain valve was calculated. x , where: T a The calibrated nitrogen purging start time is used, and the excess drainage coefficient α ranges from 0 < α ≤ 2. This invention also discloses a single-valve drainage and nitrogen purging system for a fuel cell, which can update the opening and closing cycle of the drainage valve according to different situations, ensuring timely discharge of nitrogen and water from the hydrogen side, restoring the minimum single-cell voltage to the normal range, effectively slowing down the fuel cell system's degradation rate, and extending the fuel cell system's service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cell, in particular to a single-valve water and nitrogen discharge control method and system of a fuel cell system. BACKGROUND

[0002] When the fuel cell engine is working, nitrogen and water will penetrate from the cathode to the anode of the fuel cell. As the anode side is a circulation cavity, if the nitrogen concentration accumulated on the anode side reaches a certain value, it will directly affect the metering ratio of hydrogen, and thus the problem of “hydrogen starvation” caused by insufficient hydrogen supply will occur, which not only reduces the utilization rate of hydrogen, but also reduces the reaction efficiency of the stack.

[0003] In the prior art, a nitrogen discharge valve is generally installed on the anode of the fuel cell engine, which is used to discharge nitrogen from the anode of the fuel cell engine. The water generated by the anode also needs to be discharged from the fuel cell system in time through a water discharge valve, otherwise it will cause waterlogging of the anode, cause the anode to lack gas, and seriously affect the service life of the fuel cell.

[0004] In addition, when the fuel cell engine is working, the water and nitrogen generated by the anode will also be affected by the external environment (such as atmospheric pressure, temperature, humidity, etc.) and the operating conditions (such as the working current, pressure, flow, humidity, temperature, etc. of the fuel cell). If the water and nitrogen discharge strategy of the fuel cell engine is not properly formulated, for example, excessive discharge will cause the utilization rate of hydrogen to decrease. SUMMARY

[0005] In view of the fact that the prior art cannot timely respond to various changes in the fuel cell by fixedly opening the water discharge valve periodically to discharge the hydrogen side of the fuel cell system, and is prone to cause the problem of untimely discharge of water and nitrogen, the purpose of the present application is to provide a single-valve water and nitrogen discharge control method and system of a fuel cell system, so as to solve the technical problem of decrease in the utilization rate of hydrogen caused by improper water and nitrogen discharge strategy of the fuel cell engine in the prior art.

[0006] To solve the above problems, the first purpose of the present application is to provide a single-valve water and nitrogen discharge control method of a fuel cell system, which comprises:

[0007] S 100 : calculating the water amount W in the water storage chamber of the gas-water separator a ;

[0008] After the water discharge valve is closed in the last period, the current under different working conditions and the running time are obtained in real time, the water production rate S a = f(I) under different working current conditions is obtained, and then the water amount W a in the water storage chamber of the gas-water separator is calculated as follows: a =∑Sa *ΔT;

[0009] S 200 : calculating the actual total opening time T of the drain valve x1 ;

[0010] obtaining the pressure difference P of both sides of the gas-water separator, f(P)=f(t) and the water amount W a , obtaining the actual total opening time T of the water discharge in the water storage chamber of the gas-water separator x1 ;

[0011] S 300 : calculating the first total opening time T of the drain valve x ;

[0012] According to T x =T x1 +αT a , the first total opening time T of the drain valve is calculated x , wherein: T a is the calibrated nitrogen discharge opening time, and the value range of the nitrogen discharge excess coefficient α is 0<α≤2.

[0013] Further, it further comprises:

[0014] S 400 : obtaining the closing time after the nitrogen discharge of the drain valve is closed in the last period, and determining whether to open the drain valve for nitrogen discharge based on the nitrogen discharge period;

[0015] S 500 : if nitrogen discharge is needed, detecting the water amount V in the water storage chamber of the gas-water separator to re-determine the first total opening time T of the drain valve x .

[0016] Further, in step S 500 , when the nitrogen discharge is needed, the water amount V in the water storage chamber of the gas-water separator is detected to re-determine the first total opening time T of the drain valve x , specifically comprising:

[0017] Step S 510 : when the water amount V in the water storage chamber of the gas-water separator is not lower than the water amount V0 corresponding to the detection line of the liquid level sensor, the drain valve is opened, and after the liquid surface of the water storage chamber of the gas-water separator drops to the detection line of the liquid level sensor, the drain valve is closed after the second total opening time T x2 ;

[0018] Wherein, T x2 =f(t)+α2T aIn the formula, f(t) is obtained based on the pressure difference P on both sides of the gas-water separator and f(P) = f(t); the value range of the second excess drainage coefficient α2 is 0 < α2 ≤ 2; or

[0019] Step S 520 When the water volume V in the water storage chamber of the gas-water separator is lower than the water volume V0 corresponding to the detection line of the liquid level sensor, the drain valve opens for the first total opening time T. x Then close.

[0020] Furthermore, the nitrogen removal cycle satisfies: T d =βT s In the formula, T d The nitrogen removal cycle is T. s The calibrated nitrogen removal cycle is β, which is the nitrogen removal coefficient, 0.2≤β≤1.2.

[0021] Furthermore, it also includes:

[0022] S 610 Obtain the closing time of the drain valve after it closed in the previous cycle, based on the drain interval time T. x3 Determine whether to open the drain valve to drain water;

[0023] S 620 If drainage is required, the drain valve is opened until the liquid level in the water storage chamber of the gas-water separator drops to the detection line of the liquid level sensor and then closes.

[0024] Furthermore, the drainage interval T x3 satisfy:

[0025] T x3 =α3V2 / S a

[0026] In the formula, T x3 The drainage interval time is α3, which is the third drainage excess coefficient and 0.3 < α3 ≤ 0.8; V2 = V1 - V0, where V1 is the total water volume in the water storage chamber of the gas-water separator, V0 is the water volume corresponding to the detection line of the liquid level sensor, and V2 is the discharge water volume of the gas-water separator.

[0027] Furthermore, it also includes:

[0028] S 710 The drainage signal is obtained when the liquid level in the water storage chamber of the gas-water separator reaches the detection line of the liquid level sensor.

[0029] S 720 : Obtain the gas pressure P of the gas-water separator w1 And atmospheric pressure P in the atmospheric environment a1 The pressure difference P between the two sides is obtained, where P = Pw1 -P a1 ;

[0030] S 730 : obtaining f(t) according to the two-side pressure difference P and f(P) = f(t); wherein, the f(t) is the time required by the water quantity V0 discharged by the drain valve under the two-side pressure difference P, and V0 is the water quantity corresponding to the detection line of the liquid level sensor;

[0031] S 740 : calculating the second drain opening duration T w = α1*f(t), wherein: α1 is a first drain excess coefficient and 0 < α1 ≤ 1;

[0032] S 750 : closing the drain valve after opening for the second drain opening duration T w .

[0033] Further, it further comprises:

[0034] S 810 : obtaining a minimum single cell voltage value V m of the fuel cell;

[0035] S 820 : obtaining a reduction amount ΔT m of the minimum single cell voltage value V m within a time ΔT1;

[0036] S 830 : judging whether the reduction amount ΔT m is greater than a set value a, and if yes, closing the drain valve after opening for the first opening total duration T x .

[0037] A second object of the present application is to provide a single-valve drainage and nitrogen discharge control system of a fuel cell system, comprising: a fuel cell, a hydrogen system and a controller for executing the single-valve drainage and nitrogen discharge control method of the fuel cell system; wherein:

[0038] The hydrogen system comprises a hydrogen supply device, a hydrogen ejector and a gas-water separator, one end of the hydrogen ejector is connected with the hydrogen supply device, and the other end is connected with a hydrogen inlet of the fuel cell;

[0039] The gas-water separator is connected with a hydrogen outlet of the fuel cell at an air inlet water end, a lower end of the gas-water separator is provided with a water storage chamber, and the water storage chamber is internally provided with a liquid level sensor and a drain valve;

[0040] A second pressure sensor is further arranged on the gas-water separator; and an air outlet end of the gas-water separator is connected with a backflow end of the hydrogen ejector.

[0041] The controller is connected with the fuel cell, the hydrogen system, the liquid level sensor, the drain valve and the second pressure sensor respectively.

[0042] A third object of the present application is to provide a computer readable storage medium, the storage medium stores at least one instruction, the instruction is loaded and executed by the processor, and the operation of the single valve drainage and nitrogen discharge control method of the fuel cell system is realized.

[0043] Compared with the prior art, the present application has the following beneficial effects:

[0044] 1. The single valve drainage and nitrogen discharge control method of the fuel cell system can obtain the time required for the water in the water storage chamber to be discharged by obtaining the pressure difference between the two sides of the gas-water separator, so as to calibrate the drainage opening time and the drainage period of the drainage valve for discharging the water in the water storage chamber; the single cell voltage can be accurately detected by the single cell monitoring device in the fuel cell system, so as to calibrate the nitrogen discharge opening time and the nitrogen discharge period of the fuel cell system under different working current conditions, and the anode liquid water generation rate; after the drainage period and the nitrogen discharge period of the fuel cell system are calibrated, the single cell voltage will decrease due to the decrease of the hydrogen concentration, the real-time current of the fuel cell system is obtained, and it is judged whether nitrogen discharge is needed at the same time of drainage according to the actual situation, so as to update the opening and closing period of the drainage valve, ensure that the hydrogen side nitrogen and excess water are discharged in time, and make the minimum single cell voltage recover to the normal range, which can effectively slow down the attenuation rate of the fuel cell system and prolong the service life of the fuel cell system.

[0045] 2. The hydrogen side of the fuel cell system is provided with a gas-water separator, the lower part of the gas-water separator is provided with a water storage chamber, and the water storage chamber is provided with a liquid level sensor, so that the drainage can be efficiently carried out, the problem of over-drainage of the drainage valve is reduced, and the hydrogen utilization rate is improved.

[0046] 3. The hydrogen side of the fuel cell system is provided with a gas-water separator, and the gas-water separator is provided with only one drainage valve, which can realize the functions of the previous drainage valve and nitrogen discharge valve at the same time.

[0047] 4. The controller for executing the single valve drainage and nitrogen discharge control method of the fuel cell system can control the update of the opening and closing period of the drainage valve according to different situations, ensure that the hydrogen side nitrogen and excess water are discharged in time, make the minimum single cell voltage recover to the normal range, effectively slow down the attenuation rate of the fuel cell system, and prolong the service life of the fuel cell system. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 It is a flowchart of the single valve drainage and nitrogen discharge control method of the fuel cell system in the embodiments of the present application.

[0049] Figure 2 Step S in the single-valve drainage and nitrogen removal control method of the fuel cell system in this embodiment of the invention. 400- S 500 A flowchart;

[0050] Figure 3 Step S in the single-valve drainage and nitrogen removal control method of the fuel cell system in this embodiment of the invention. 500 A detailed flowchart;

[0051] Figure 4 Step S in the single-valve drainage and nitrogen removal control method of the fuel cell system in this embodiment of the invention. 600 A detailed flowchart;

[0052] Figure 5 Step S in the single-valve drainage and nitrogen removal control method of the fuel cell system in this embodiment of the invention. 700 A detailed flowchart;

[0053] Figure 6 Step S in the single-valve drainage and nitrogen removal control method of the fuel cell system in this embodiment of the invention. 800 A detailed flowchart;

[0054] Figure 7 This is a schematic diagram of the drainage and nitrogen removal system of the fuel cell system in an embodiment of the present invention.

[0055] Explanation of reference numerals in the attached figures:

[0056] H-1, Hydrogen storage device; H-2, Bottle valve; H-3, Hydrogen inlet solenoid valve; H-4, Hydrogen proportioning valve; H-5, Hydrogen ejector; H-6, First pressure sensor; H-7, Fuel cell; H-8, Second pressure sensor; H-9, Gas-liquid separator; H-10, Liquid level sensor; H-11, Drain valve. Detailed Implementation

[0057] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] In the description of this invention, it should be noted that the terms "first," "second," etc., are used for descriptive purposes and should not be construed as indicating or implying relative importance.

[0059] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or internal communication of two elements, it can be wireless connection, or wired connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0060] In addition, the technical features involved in the different embodiments of the application described below can be combined with each other as long as there is no conflict between them.

[0061] A fuel cell is an electrochemical reaction device in which hydrogen and oxygen react in two half-electrodes to generate water, converting chemical energy into electrical energy, accompanied by efficiency loss into heat energy. A fuel cell stack is formed by connecting multiple fuel cell single pieces in series in the negative-positive-negative-positive pattern, and the adjacent two fuel cell single pieces are separated by a bipolar plate. A hydrogen supply flow channel is formed on one side surface of the bipolar plate and contacts the hydrogen reaction electrode, an oxygen supply flow channel is formed on the other side surface of the bipolar plate and contacts the oxygen reaction electrode, and a cooling liquid supply channel is formed in the middle of the bipolar plate. Different medium flow channels are sealed by a sealing material.

[0062] In order to improve the utilization rate of hydrogen, the hydrogen side is generally in a semi-closed state during the operation of the fuel cell system, and the exhaust valve is intermittently opened to discharge nitrogen and other impurities in the hydrogen side. However, due to the concentration difference between the hydrogen side and the oxygen side, nitrogen in the oxygen side will penetrate through the proton exchange membrane to the hydrogen side. At the same time, the hydrogen used in the fuel cell system is not 100% pure hydrogen. Therefore, during the closing stage of the exhaust valve, nitrogen and other impurities in the hydrogen side will accumulate, resulting in a decrease in hydrogen concentration, which will affect the performance of the fuel cell. If not discharged in time, the hydrogen concentration will continue to decrease, causing local gas shortage in the fuel cell system and damaging the service life of the fuel cell.

[0063] The existing fuel cell system generally uses a bench calibration exhaust valve and works according to a fixed opening-closing time period. However, the gas concentration in the stack, the thickness of the proton membrane and the void will change with the running time of the stack. At the same time, different nitrogen permeation rates and different hydrogen purity will also cause different amounts of impurities to accumulate in a unit of time, resulting in that the exhaust valve cannot be opened and closed in time according to the fixed time period, and thus the service life of the fuel cell is reduced.

[0064] To solve the above technical problems, please refer to Figures 1-7As shown, this embodiment of the invention provides a single-valve drainage and nitrogen removal control method for a fuel cell system. The single-valve drainage and nitrogen removal control method includes: S 100 Calculate the water volume W in the water storage chamber of the gas-water separator. a ;

[0065] After the drain valve closes in the previous cycle, the current and running time under different operating conditions are acquired in real time, and the water production rate S is determined accordingly. a =f(I), to obtain the water production rate S under different operating currents. a The amount of water W in the water storage chamber of the gas-water separator a =ΣS a *ΔT;

[0066] S 200 Calculate the total actual opening time T of the drain valve. x1 ;

[0067] Based on the pressure difference P across the gas-liquid separator, according to f(P) = f(t) and the water volume W a The actual total operating time T after the water in the water storage chamber of the gas-water separator is completely drained is obtained. x1 ;

[0068] S 300 Calculate the total first opening time T of the drain valve. x ;

[0069] According to T x =T x1 +αT a The first total opening time T of the drain valve was calculated. x , where: T a For the calibrated nitrogen discharge opening duration, the excess drainage coefficient α ranges from 0 < α ≤ 2. In a preferred embodiment, the excess drainage coefficient α is selected as 0.5 ≤ α ≤ 2, which allows for a more accurate calculation of the first total opening duration T of the drain valve based on the actual operating conditions. x .

[0070] It should be noted that, in this embodiment of the invention, the water volume W a The unit is L, and the water production rate is S. a The unit is L / s, the unit of pressure difference P is kPa, and the actual total opening time T of the drain valve is... x1 The unit is s. Of course, in practical applications, it can be converted to other units of measurement, but the unit conversion requirements on both sides of the equation should be met, and scientific principles should not be violated.

[0071] In addition, the closing and opening time values of the drain valve and the comparison relationship of the calibration value of the drain valve in the embodiment can come from experimental data or modeling statistical data; in addition, it is particularly pointed out that the steps in the disclosure are not limited in the order, and the order between the steps can be adjusted unless there is a real order between the steps.

[0072] Specifically, please refer to Figure 2 In some embodiments of the present application, the single-valve drainage and nitrogen discharge control method further comprises:

[0073] S 400 : Acquire the closing time length after the nitrogen discharge of the drain valve in the last period, and determine whether to open the drain valve for nitrogen discharge based on the nitrogen discharge period.

[0074] S 500 : If nitrogen discharge is needed, detect the water volume V in the water storage chamber of the gas-water separator to re-determine the first total opening time T x of the drain valve.

[0075] Specifically, please refer to Figure 3 In some embodiments of the present application, in step S 600 , if nitrogen discharge is needed, detecting the water volume V in the water storage chamber of the gas-water separator to re-determine the first total opening time T x of the drain valve specifically comprises:

[0076] Step S 510 : When the water volume V in the water storage chamber of the gas-water separator is not less than the water volume V0 corresponding to the detection line of the liquid level sensor, open the drain valve, and continue to close after the second total opening time T x2 when the liquid level in the water storage chamber of the gas-water separator drops to the detection line of the liquid level sensor.

[0077] Wherein, T x2 = f(t) + a2T a , in the formula, f(t) is obtained based on the pressure difference P of both sides of the gas-water separator and f(P) = f(t); the value range of the second drain excess coefficient a2 is 0 < a2 ≤ 2.

[0078] In this implementation, whether the water volume V in the gas-water separator's water storage chamber is not less than the water volume V0 corresponding to the detection line of the liquid level sensor can be determined based on whether the liquid level in the gas-water separator's water storage chamber is at or above the detection line of the liquid level sensor during the current nitrogen removal cycle or drainage cycle. Specifically, the judgment benchmark is based on the liquid level detected by the liquid level sensor (i.e., the liquid level in the gas-water separator's water storage chamber just reaches the detection line of the liquid level sensor). Before this, the water volume V in the gas-water separator's water storage chamber is lower than the water volume V0 corresponding to the detection line of the liquid level sensor; after this, the water volume V in the gas-water separator's water storage chamber is not lower than the water volume V0 corresponding to the detection line of the liquid level sensor.

[0079] In some other embodiments of the present invention, step S is also included. 520 When the water level V in the water storage chamber of the gas-water separator is lower than the water level V0 corresponding to the detection line of the liquid level sensor, the drain valve opens for the first total opening time T. x Then close.

[0080] In the embodiments of the present invention, step S 200 The specific steps include:

[0081] Obtain the current value P of the gas-water separator (i.e., the second pressure sensor H-8 in the following text). w The current air pressure P) w and the current atmospheric pressure P a The pressure difference P between the two sides is obtained, where P = P w -P a ;

[0082] Based on the calibrated f(P) = f(t), f(t) can also be obtained when the pressure difference P between the two sides is known. Since f(P) = f(t) is calculated under different pressure differences P within the gas-liquid separator, when the water level in the storage chamber reaches the detection line of the level sensor (i.e., the water volume V0 corresponding to the detection line of the level sensor (this value is known)), the drain valve is opened to drain the water, obtaining the time t required for the water in the storage chamber to be completely drained. Therefore, based on the water volume V0 corresponding to the detection line of the level sensor and f(t), the drainage rate corresponding to the pressure difference P between the two sides can be obtained as V0 / f(t) = V0 / the time t corresponding to the pressure difference between the two sides; hence, T x1 Water volume W a Divide by the quotient of the drainage rate corresponding to the pressure difference P on both sides, that is: T x1 =W a / (V0 / f(t)=V0 / time t corresponding to the pressure difference on both sides).

[0083] Specifically, in this embodiment, under the pressure difference P on both sides of the calibrated gas-water separator (P is the gauge pressure, and the external atmospheric pressure is 100 kPa during calibration), when the water level in the water storage chamber reaches the detection line, the drain valve is opened to drain the water, and the time t required for the water to be completely drained is f(t) = f(P).

[0084] Specifically, please refer to Figure 4 As shown, in some embodiments of the present invention, the single-valve drainage and nitrogen removal control method further includes step S. 600 The specific steps are as follows:

[0085] S 610 : Obtain the closing time of the drain valve after it closed in the previous cycle, based on the drain interval time T. x3 Determine whether to open the drain valve to drain water;

[0086] S 620 If drainage is required, the drain valve is opened until the liquid level in the water storage chamber of the gas-liquid separator drops to the detection line of the liquid level sensor and then closes.

[0087] Wherein, the drainage interval time T x3 satisfy:

[0088] T x3 =α3V2 / S a

[0089] In the formula, T x3 α3 is the drainage interval; α3 is the third drainage excess coefficient and 0.3 < α3 ≤ 0.8; V2 = V1 - V0, where V1 is the total water volume in the gas-water separator's water storage chamber, V0 is the water volume corresponding to the detection line of the liquid level sensor, and V2 is the discharge water volume of the gas-water separator.

[0090] In this embodiment, the drainage interval T x3 This refers to the time interval between the closing of the drain valve in the previous cycle and the opening of the drain valve in the next cycle to achieve drainage. This embodiment applies to situations where the drain valve stops draining based on the liquid level in the water storage chamber of the gas-liquid separator dropping to the detection line of the liquid level sensor, and the detection signal from the liquid level sensor can be used as the judgment criterion.

[0091] Please see Figure 5 As shown, in some embodiments of the present invention, the single-valve drainage and nitrogen removal control method further includes step S. 700 The specific operation process includes the following:

[0092] S 710 : Obtain the drainage signal when the liquid level in the water storage chamber of the gas-liquid separator reaches the detection line of the liquid level sensor;

[0093] S 720 : Obtain the gas pressure P of the gas-water separatorw1 And atmospheric pressure P in the atmospheric environment a1 The pressure difference P between the two sides of the gas-water separator is obtained as P = P w1 -P a1 ;

[0094] S 730 Based on the pressure difference P on both sides and f(P) = f(t), we obtain f(t); where f(t) is the time required for the drain valve to discharge water of volume V0 under the pressure difference P on both sides, and V0 is the water volume corresponding to the detection line of the liquid level sensor.

[0095] S 740 Calculate the second drainage opening time T w =α1*f(t), where: α1 is the first excess drainage coefficient and 0<α1≤1;

[0096] S 750 : Drain valve opens, second drain opening time T w Then close.

[0097] This embodiment applies to situations where the drain valve opens based on the liquid level in the water storage chamber of the gas-water separator rising to the detection line of the liquid level sensor, and the detection signal from the liquid level sensor can be used as the judgment criterion.

[0098] Specifically, please refer to Figure 6 As shown, in some embodiments of the present invention, the single-valve drainage and nitrogen removal control method further includes step S. 800 The specific operation process is as follows:

[0099] S 810 : Obtain the minimum single-cell voltage value V of the fuel cell m ;

[0100] S 820 Under constant current conditions, obtain the minimum single-cell battery voltage value V. m The decrease ΔT within time ΔT1 m ;

[0101] S 830 Determine the decrease ΔT m If the value is greater than the set value 'a', then the drain valve will open for the first total opening time T. x Then close.

[0102] Preferably, in the above embodiment, the value range of time ΔT1 is 0 < ΔT1 ≤ 5 min, and the value range of set value a is 1 mV ≤ a ≤ 5 mV.

[0103] The embodiment considers that the fuel cell will decay after a certain period of operation, and the single cell voltage value will decrease when the stack is normally operated, so the minimum single cell voltage threshold of the fuel cell system will be self-calibrated with the operation of the fuel cell system, and the calibration method can be operation data statistics or modeling statistical data, so as to ensure the effectiveness of the minimum single cell voltage threshold of the fuel cell system.

[0104] Specifically, in the embodiment of the application, the single cell monitoring device is installed on the fuel cell system, which can accurately detect the single cell voltage. The decrease of hydrogen concentration will cause the decrease of single cell voltage, and then identify the accumulation time of nitrogen and other impurities on the hydrogen side, so that the drain valve can update the closing time of the drain valve according to different situations, and then update the actual drainage cycle of the drain valve, so that the drain valve is opened and closed through the actual drainage cycle updated in real time, and the nitrogen and other impurities on the hydrogen side of the fuel cell system stack are discharged in time.

[0105] Specifically, in some embodiments of the application, step S 400 , the calculation expression of the nitrogen discharge period T d is as follows:

[0106] T d = βT s

[0107] Wherein: T d is the nitrogen discharge period, T s is the calibrated nitrogen discharge period, and β is the nitrogen discharge coefficient, 0.2≤β≤1.2.

[0108] The nitrogen discharge period T d of the embodiment is the time length between the opening of the drain valve twice to realize nitrogen discharge.

[0109] Specifically, in some embodiments of the application, before step S 100 , it further includes the following steps: the calibration calculation method of the calibrated drain valve opening time T a and the calibrated nitrogen discharge period T s includes:

[0110] Under a certain operating current, the single cell voltage and the minimum single cell voltage of the fuel cell system are obtained, and the minimum single cell voltage is compared with the minimum single cell voltage threshold to obtain the nitrogen discharge opening time T a under the working condition;

[0111] Keep the nitrogen discharge opening time T a unchanged, adjust the nitrogen discharge period from small to large, so that the minimum single cell voltage V min is less than the minimum single cell voltage threshold V m1 , thereby obtaining the calibrated nitrogen discharge period Ts The maximum value;

[0112] Calculate the nitrogen purging cycle T of the drain valve d ;

[0113] According to T d =βT s Calculate the nitrogen expulsion cycle T d T s For the calibrated nitrogen removal cycle, the nitrogen removal excess coefficient β ranges from 0.2 ≤ β ≤ 1.2. In this embodiment, the nitrogen removal cycle T under the current corresponding operating condition can be obtained. d Nitrogen removal cycle T under different operating current conditions d The controller can obtain the corresponding current based on the current operating condition.

[0114] Please see Figure 7 As shown in the figure, this embodiment of the invention also discloses a drainage and nitrogen removal system for a fuel cell system. The drainage and nitrogen removal system includes a fuel cell H-7, a hydrogen system, and a controller (not shown in the figure) for executing the single-valve drainage and nitrogen removal control method for the fuel cell system described above.

[0115] The hydrogen system includes a hydrogen supply unit, a hydrogen ejector H-5, and a gas-liquid separator H-9. One end of the hydrogen ejector H-5 is connected to the hydrogen supply unit, and the other end is connected to the anode (hydrogen inlet) of the fuel cell H-7. A first pressure sensor H-6 is installed between the fuel cell H-7 and the hydrogen ejector H-5. The return end of the hydrogen ejector H-5 is connected to the outlet end of the gas-liquid separator H-9. The hydrogen ejector H-5 is used to replenish the fuel cell stack and control the hydrogen pressure. The water inlet end of the gas-liquid separator H-9 is connected to the hydrogen outlet of the fuel cell H-7. The gas-water separator H-9 has a water storage chamber at its lower end. Inside the water storage chamber, there is a liquid level sensor H-10 (for detecting the liquid level) and a drain valve H-11 (for draining and discharging nitrogen). The gas-water separator H-9 also has a second pressure sensor H-8, which is used to detect the gas pressure of the gas-water separator H-9. The gas outlet of the gas-water separator H-9 is connected to the return end of the hydrogen ejector H-5. The controller is connected to the fuel cell H-7, the hydrogen system, the liquid level sensor H-10, the drain valve H-11, and the second pressure sensor H-8. In this embodiment, the sensor used to detect the atmospheric pressure is connected to the controller. This sensor can be placed anywhere on the vehicle where it can detect the atmospheric pressure.

[0116] The hydrogen supply device in the embodiment comprises a hydrogen storage device H-1, a bottle mouth valve H-2, a hydrogen inlet electromagnetic valve H-3 and a hydrogen proportional valve H-4, which are connected in sequence through a gas pipeline to form a hydrogen supply system for the fuel cell H-7.

[0117] In the embodiment, the controller is electrically connected with the fuel cell H-7, the hydrogen system, the liquid level sensor H-10, the drain valve H-11, the first pressure sensor H-6 and the second pressure sensor H-8. Thus, the controller can receive relevant instructions of the fuel cell H-7, the pressure sensor, the drain valve H-11 and the like, and control the action of each valve according to the relevant information.

[0118] The function of the liquid level sensor H-10 in the embodiment is that when the liquid level in the water storage chamber of the gas-water separator reaches the detection line of the liquid level sensor, the liquid level sensor H-10 sends a liquid level state value 1, otherwise the liquid level state value is 0. The controller receives relevant instructions of the liquid level sensor H-10 and the like, and controls the action of the drain valve according to the relevant information.

[0119] The working process of the drain and nitrogen discharge system of the fuel cell system in the embodiment is as follows: when the fuel cell engine is working, the hydrogen in the hydrogen storage device H-1 enters the fuel cell H-7 through the bottle mouth valve H-2, the hydrogen inlet electromagnetic valve H-3, the hydrogen proportional valve H-4, the hydrogen ejector H-5 and the first pressure sensor H-6 in sequence. After the hydrogen, nitrogen and water vapor mixture which does not react in the fuel cell H-7 is subjected to electrochemical reaction with air, the hydrogen is returned to the hydrogen ejector H-5 from the backflow port of the gas-water separator H-9, and the water is discharged from the drain valve H-11.

[0120] It should be emphasized that, when the drain and nitrogen discharge are calibrated, the S a = f(I), f(P) = f(t), the calibrated nitrogen discharge opening time T a , the drain interval time T x3 , the calibrated nitrogen discharge period T s and other known quantities obtained based on the calibrated parameters are different from the drain and nitrogen discharge control system of the fuel cell system. The gas-water separator H-9 of the calibration system is provided with a drain valve and a nitrogen discharge valve. The drain valve is only used for draining water, and the nitrogen discharge valve is only used for discharging nitrogen. The nitrogen discharge valve is used for discharging the accumulated nitrogen and other impurities on the hydrogen side, and the drain valve is used for discharging the generated water on the hydrogen side of the stack. It should be noted that, in actual application, the calibration system and the system used in the present application are the same in other components related to the calibrated parameters, and other differences do not affect the calibration results.

[0121] Please refer to Figure 7 As shown in the figure, the lower end of the gas-water separator H-9 in the calibration system of the embodiment of the present application is provided with a water storage chamber, the height of the water storage chamber is H, the volume of the water storage chamber is V1, 20ml≤V1≤1000ml, and the volume of the water storage chamber below the detection line of the liquid level sensor H-10 is V0, wherein 0

[0122] The process of calibrating f(P)=f(t) is as follows:

[0123] When the liquid level of the water in the gas-water separator reaches the detection line of the liquid level sensor H-10 under the pressure difference P (P is the gauge pressure, and the pressure of the atmospheric environment during calibration is 100kPa) of the two sides of the gas-water separator, the drain valve is opened to drain water, and the time t required for the water to be drained is f(t)=f(P).

[0124] The nitrogen discharge time T of the fuel cell system under different working current conditions of the calibration system a The nitrogen discharge period T s , and the anode liquid water generation rate S a , and the specific calibration method is as follows:

[0125] The gas-water separator is simultaneously provided with a drain valve and a nitrogen discharge valve, the drain valve is only used for draining water, and the nitrogen discharge valve is only used for discharging nitrogen;

[0126] The system is provided with a single cell monitoring device, which can accurately detect the single cell voltage;

[0127] Run a working current point A, the opening time of the nitrogen discharge valve is T a , wherein 0 a ≤3s (other values can be set in actual application), and the opening period is T s , wherein 0 s ≤50s (other values can be set in actual application). The opening time T a remains unchanged, and the period T s is adjusted from small to large, so that the minimum single cell voltage Vmin of the fuel cell changes less than Vm1, wherein Vm1≤3mV, at this time, the maximum value of T s is the opening period of the nitrogen discharge valve;

[0128] The required opening time T a and the period T s of the nitrogen discharge are the calibration values.

[0129] Each working condition point constant current operation, gas water separator storage water room liquid level sensor detection line below the volume V0, gas water separator storage water room liquid level reaches the liquid level sensor detection line required time T, then the fuel cell system anode side water production rate Sa = V0 / T, take continuous operation 1 hour (actual application can be set to other values) within the water production rate S a The average value is the water production rate S of the working condition point a .

[0130] The water production rate S of different current points is obtained a =f(I) relationship.

[0131] The embodiment also provides a computer readable storage medium, and at least one instruction is stored in the storage medium, and when the instruction is loaded and executed by a processor, the operation of the single-valve water and nitrogen discharge control method of the fuel cell system is realized.

[0132] The embodiment ensures that the water discharge valve self-adjusts the actual water discharge period in time, and further ensures that the hydrogen side nitrogen and excess water of the fuel cell system stack are discharged in time, so that the minimum single-plate voltage is restored to the normal range, the engine attenuation rate is effectively slowed down, the engine service life is prolonged, the water discharge valve can flexibly adapt to various conditions when in use, the complexity of the fuel cell system structure is not increased, cost is saved, and the purpose of discharging water and nitrogen is achieved.

[0133] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited to this. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present disclosure.

Claims

1. A single-valve water and nitrogen discharge control method for a fuel cell system, characterized by, The single-valve water and nitrogen discharge control method comprises: S 100 : Calculate the amount of water W in the water storage chamber of the gas-water separator a ; After the drain valve closes in the previous cycle, the current and running time under different operating conditions are acquired in real time, and the water production rate S is determined accordingly. a =f(I), thus obtaining the water production rate S under different operating currents. a The amount of water W in the water storage chamber of the gas-water separator is... a =ΣS a *ΔT; S 200 : calculating the actual total opening time T of the drain valve x1 ; based on the pressure difference P of the gas-water separator, f(P)=f(t) and the water amount W a , to obtain the actual total opening time T of the water discharge of the water storage chamber of the gas-water separator x1 ; S 300 : calculating a first total opening time T of the drain valve x ; According to T x =T x1 +αT a , the first total opening time T x of the drain valve is calculated a , wherein: T a is the calibrated nitrogen opening time, and the value range of the drain excess coefficient a is 0 S 400 : obtain a closing duration after the drain valve is closed in the last period, and determine whether to open the drain valve for nitrogen removal based on the nitrogen removal period. S 500 : if nitrogen venting is required, detecting the water volume V in the water separator water reservoir to re-determine the first total opening time T of the drain valve x ; Step S 510 : When the water amount V in the water storage chamber of the air-water separator is not lower than the water amount V0 corresponding to the detection line of the liquid level sensor, the drain valve is opened, and when the liquid surface of the water storage chamber of the air-water separator drops to reach the detection line of the liquid level sensor, the second opening total time T is continued x2 and then closed. Wherein, T x2 = f(t) + a2T a , wherein f(t) is obtained based on the pressure difference P of the two sides of the gas-water separator and f(P) = f(t), and the second drainage excess coefficient a2 is in the range of 0 < a2 ≤ 2; or Step S 520 When the water amount V of the water storage chamber of the air-water separator is lower than the water amount V0 corresponding to the detection line of the liquid level sensor, the drain valve opens the first opening total time T x and then closes.

2. The single-valve water drainage and nitrogen discharge control method of a fuel cell system according to claim 1, characterized by, The nitrogen discharge period satisfies: T d = βT s , wherein T d is the nitrogen discharge period; T s is a standard nitrogen discharge period, and β is a nitrogen discharge coefficient, 0.2 ≤ β ≤ 1.

2.

3. The single-valve water drainage and nitrogen discharge control method of a fuel cell system according to any one of claims 1 to 2, characterized by, Further comprising: S 610 : obtain the closing duration after the drain valve is closed in the last period, and determine the drain interval time T x3 whether to open the drain valve for drainage; S 620 If drainage is required, the drain valve opens to the water level in the water separator reservoir drops to the level sensor detection line and closes.

4. The single-valve water drainage and nitrogen discharge control method of a fuel cell system according to claim 3, characterized by, The drain interval time T x3 satisfies: T x3 =α3V2 / S a In the formula, T x3 is the drainage interval time; a3 is a third drainage excess coefficient and 0.3 < a3 < 0.8; V2 = V1 - V0, V1 is the total water volume of the water storage chamber of the gas-water separator, V0 is the water volume corresponding to the detection line of the liquid level sensor, and V2 is the drainage water volume of the gas-water separator.

5. The single-valve water drainage and nitrogen discharge control method of a fuel cell system according to any one of claims 1 to 2, characterized by, Further comprising: S 710 , obtaining a water discharge signal when the liquid level of the water storage chamber of the air-water separator reaches a detection line of the liquid level sensor; S 720 : obtaining the gas pressure P of the gas-water separator w1 and the atmospheric pressure P of the atmospheric environment a1 , obtaining the pressure difference P between the two sides, wherein P=P w1 -P a1 ; S 730 : obtaining f(t) according to the two-side pressure difference P and f(P)=f(t); wherein, the f(t) is a time required for the water discharged by the drain valve under the two-side pressure difference P to reach the water volume V0, and the V0 is a water volume corresponding to a detection line of the liquid level sensor; S 740 : calculating the second drain opening duration T w = α1* f(t), where: α1 is a first drain excess coefficient and 0 < α1 ≤ 1; S 750 : the second drain opening duration T w after opening.

6. The single-valve water drainage and nitrogen discharge control method of a fuel cell system according to any one of claims 1 to 2, characterized by, Further comprising: S 810 : acquiring a minimum single cell voltage value V m of the fuel cell S 820 : obtaining the minimum monolithic cell voltage value V m the decrease ΔT in the time ΔT1 m ; S 830 : judges whether the reduction amount ΔT m is greater than a set value a, and if so, the drain valve opens for the first total opening time T x and then closes.

7. A single-valve drainage and nitrogen removal control system for a fuel cell system, characterized in that, Including: A fuel cell, a hydrogen system and a controller for implementing the single-valve water and nitrogen discharge control method of the fuel cell system according to any one of claims 1-6; wherein: The hydrogen system comprises a hydrogen supply device, a hydrogen ejector and a gas-water separator, one end of the hydrogen ejector is connected with the hydrogen supply device, and the other end is connected with a hydrogen inlet of the fuel cell; The gas-water separator is connected with a hydrogen outlet of the fuel cell at an air inlet water end, a lower end of the gas-water separator is provided with a water storage chamber, the water storage chamber is provided with a liquid level sensor and a water discharge valve; a second pressure sensor is further arranged on the gas-water separator; and an air outlet end of the gas-water separator is connected with a backflow end of the hydrogen ejector; The controller is connected with the fuel cell, the hydrogen system, the liquid level sensor, the water discharge valve and the second pressure sensor respectively.

8. A computer readable storage medium having stored therein at least one instruction, the medium comprising: The instructions are loaded and executed by the processor to implement the single-valve water and nitrogen discharge control method of the fuel cell system according to any one of claims 1-6.

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