Fuel cell system gas-water separator-based lowest liquid level detection method and drainage period correction method and system

Abstract

The invention belongs to the technical field of fuel cells, and provides a minimum liquid level detection and drainage cycle correction method and system based on a gas-water separator of a fuel cell system. According to the lowest liquid level detection method, an electric heating drainage electromagnetic valve on the gas-water separator is used for heating a valve element part, the liquid level is judged by comparing the temperature difference value before and after heating with a preset threshold value, and cost increase and fault risks caused by the liquid level and a pressure sensor are avoided. The drainage period correction method sets an integral weight according to the relationship between the working current of the electric pile and the anode displacement, accumulatively calculates the displacement and compares the displacement with a preset value to control drainage. The drainage judgment value is adjusted according to the temperature change monitored by the electric heating drainage electromagnetic valve after drainage, and insufficient or excessive drainage is prevented. According to the invention, no additional sensor is needed, the liquid level can be accurately controlled, the hydrogen discharge is reduced, the hydrogen utilization rate is improved, the stable operation of the fuel cell system is ensured, and the problems of liquid level detection and drainage control in the prior art are effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a minimum liquid level detection method and a drainage cycle correction method and system based on a gas-water separator of a fuel cell system. Background Art

[0002] Proton exchange membrane fuel cells use hydrogen and oxygen in the air to undergo an electrochemical reaction to drive the load of an external circuit, and the only reaction product is water. It is precisely because of the high efficiency and zero emission characteristics of the fuel cell system that it has been widely used in the fields of automotive power systems and stationary power generation.

[0003] Circulating the hydrogen at the outlet of the fuel cell system can increase the hydrogen metering ratio entering the stack and humidify the hydrogen at the inlet of the stack. However, the hydrogen outlet of the fuel cell carries liquid water. If it is directly circulated without separation, on the one hand, it will shorten the service life of the hydrogen circulation pump. On the other hand, when liquid water enters the inlet of the stack, it will block the hydrogen flow channel, causing the voltage of the first few cells near the inlet of the stack to be low. Therefore, liquid water must be separated when hydrogen is circulated.

[0004] When the liquid water separated from the gas-water separator accumulates to a certain level, it should be discharged in a timely and appropriate amount. However, it is necessary to prevent the discharge volume from being lower than the separated water volume, causing the maximum liquid level to continue to increase. At the same time, it is necessary to prevent frequent over-discharge from causing hydrogen in the separator to be discharged accidentally, affecting the hydrogen utilization rate.

[0005] The current mainstream solution is to rely on 1 to 2 liquid level sensors to complete liquid level detection and serve as the basis for opening and closing the drain valve. When the liquid level reaches the high level, the drain valve is opened, and when the liquid level is lower than the low level, the drain valve is closed. Alternatively, by setting a pressure sensor, when the liquid water at the bottom of the gas-water separator is drained, the gas begins to be discharged. The discharged gas will cause pressure fluctuations in the gas-water separator cavity, thereby completing the judgment that the water storage at the bottom of the gas-water separator has been drained.

[0006] For example, patent CN110854414A mainly relies on two liquid level switch signals to determine the opening time of the solenoid valve and whether the drainage is successfully completed. It requires a lot of sensor hardware resources. Another basis for judging whether the water is completely drained is that after the water is drained, the gas will continue to be discharged, causing pressure fluctuations (detected by a pressure sensor), but this will cause a small amount of hydrogen to be discharged after each drainage, affecting the utilization rate of hydrogen.

[0007] The following technical problems still exist in the prior art:

[0008] (1) The existing solution of detecting the liquid level through a liquid level sensor requires additional hardware resources, which increases the cost of parts. In addition, when the liquid level shakes, the liquid level sensor cannot accurately measure. The failure of the liquid level sensor itself will also cause a series of problems in anode drainage, and in severe cases, it will cause a failure and shutdown.

[0009] (2) Although the method of using a pressure sensor to determine whether the stored water has been drained is effective, a certain amount of hydrogen is discharged each time the water is drained, which reduces the utilization rate of the hydrogen. Summary of the invention

[0010] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a minimum liquid level detection method and drainage cycle correction method and system based on the gas-water separator of the fuel cell system. The present invention makes full use of the electric heating drainage valve installed in the gas-water separator to detect the zero liquid level / minimum liquid level in the separator, and combines a certain drainage cycle correction strategy to always maintain the liquid level in the hydrogen gas-water separator within a reasonable range. It can prevent both long-term insufficient drainage and hydrogen discharge caused by excessive drainage each time, which affects the utilization rate of hydrogen.

[0011] In order to solve the above technical problems, the present invention is implemented by the following technical solutions:

[0012] In a first aspect, the present invention provides a method for detecting a minimum liquid level of a gas-water separator in a fuel cell system, comprising the following steps:

[0013] The valve core of the electric heating drainage solenoid valve installed on the gas-water separator is heated;

[0014] Measure and record the initial temperature value at the beginning of heating. After heating continues for a period of time, measure and record the current temperature value again, and calculate the temperature difference between the two measurements.

[0015] The temperature difference is compared with the preset temperature threshold. If the temperature difference is less than the preset temperature threshold, the liquid level in the gas-water separator is higher than the preset minimum liquid level; if the temperature difference is equal to the preset temperature threshold, the liquid level in the gas-water separator is at the preset minimum liquid level; if the temperature difference is greater than the preset temperature threshold, the liquid level in the gas-water separator is lower than the preset minimum liquid level.

[0016] As a further optimization scheme of the present invention, the preset temperature threshold is the temperature difference of water corresponding to a predetermined minimum liquid level in the gas-water separator when heated under the same conditions.

[0017] As a further optimization scheme of the present invention, the electric heating drainage solenoid valve includes a solenoid valve body, and the connection between the solenoid valve body and the gas-water separator is provided with a heating and temperature measuring component for heating and measuring the temperature of the water stored at the bottom of the gas-water separator, and a sealing ring, and a drain outlet is provided at the bottom of the solenoid valve body.

[0018] In a second aspect, the present invention provides a minimum liquid level detection system based on a gas-water separator of a fuel cell system, which is used to perform the minimum liquid level detection method, and the system comprises:

[0019] A gas-water separator, used to separate liquid water carried by the hydrogen outlet of the fuel cell;

[0020] An electric heating and drainage solenoid valve is installed on the gas-water separator and is used to perform heating, temperature measurement and drainage operations;

[0021] A control module, used for controlling the heating of the valve core of the electric heating drain solenoid valve;

[0022] The data acquisition and calculation module is used to measure and record the initial temperature value at the beginning of heating, and to measure and record the current temperature value after heating continues for a period of time, and calculate the temperature difference between the two measurements;

[0023] The judgment output module is used to compare the calculated temperature difference with a preset temperature threshold, and judge whether the liquid level in the gas-water separator is higher than, equal to or lower than a preset minimum liquid level according to the comparison result.

[0024] In a third aspect, the present invention provides a method for correcting a drainage cycle based on a gas-water separator of a fuel cell system, comprising the following steps:

[0025] According to the relationship between the working current of the fuel cell stack and the anode water discharge, the water discharge integral weight under different working currents is set;

[0026] The anode drainage volume C within a period of time is accumulated and calculated, and compared with a preset drainage judgment value C1, and a drainage operation is performed when the accumulated drainage volume C reaches or exceeds the drainage judgment value C1;

[0027] After drainage, the electric heating drainage solenoid valve installed on the gas-water separator is used for heating and temperature monitoring, and the subsequent drainage judgment value C1 is adjusted according to the temperature change to avoid insufficient drainage or excessive drainage.

[0028] As a further optimization scheme of the present invention, the relationship between the working current of the battery stack and the anode water discharge is as follows:

[0029] η=f(I)

[0030] C = ∫η·dt

[0031] In the above formula, η is the integral weight of the water discharge calculation under different fuel cell stack operating currents, I is the fuel cell stack operating current, and C is the cumulative water discharge of the anode within any period of time.

[0032] As a further optimization scheme of the present invention, when the electric heating drainage solenoid valve is opened to drain water, the accumulated drainage volume C should be reset to 0 and a new round of integral calculation should be started.

[0033] As a further optimization scheme of the present invention, when the drainage is finished, the electric heating drainage solenoid valve is turned on for heating and temperature measurement monitoring, and the temperature value T1 at that time is recorded. After heating for a period of time, the temperature value T2 is read again, and the temperature difference ΔT=T2-T1 is calculated;

[0034] When the temperature difference ΔT<T', it is considered that there is still a certain amount of liquid left in the liquid storage chamber after drainage. At this time, the drainage judgment value C1=C1-β should be reduced, and the number of times the threshold value is reduced N should be counted through the counter. When N≥preset fault value n, a drainage fault is reported;

[0035] When the temperature difference ΔT≥T', it is considered that the current drainage has drained all the stored liquid. At this time, the drainage judgment value C1=C1+α should be increased, and the interval time between two drainages should be increased. At the same time, the number of times the counter statistical threshold is reduced N is reset to 0, and the number of times the drainage judgment value C1 is reduced is restarted.

[0036] As a further optimization scheme of the present invention, during the calibration process, the setting of the β value is adjusted according to the count value N of the counter when ΔT≥T' at that time, so as to ensure that when the drainage judgment value is reduced to C1=C1-β and updated to 5 to 8 cycles, the water can be drained once; at the same time, the α value is set to 5 to 8 times the β value, and the preset fault value n should be set greater than the α / β value.

[0037] In a fourth aspect, the present invention provides a drainage cycle correction system based on a gas-water separator of a fuel cell system, which is used to execute the drainage cycle correction method, and the system comprises:

[0038] A gas-water separator, used to separate liquid water carried by the hydrogen outlet of the fuel cell;

[0039] An electric heating and drainage solenoid valve is installed on the gas-water separator and is used to perform heating, temperature measurement and drainage operations;

[0040] An integral weight setting module, which sets the integral weight of the water discharge under different working currents according to the relationship between the working current of the fuel cell stack and the anode water discharge;

[0041] A cumulative water discharge calculation module, which calculates the anode water discharge C within a period of time according to the integral weight setting module;

[0042] A drainage control module, which compares the accumulated drainage volume C with a preset drainage judgment value C1, and controls the electric heating drainage solenoid valve to perform drainage operation when the accumulated drainage volume C reaches or exceeds the drainage judgment value C1, and resets the accumulated drainage volume C during drainage;

[0043] The drainage effect monitoring module controls the electric heating drainage solenoid valve to perform heating and temperature monitoring at the end of drainage, and adjusts the subsequent drainage judgment value C1 according to the temperature change to avoid insufficient or excessive drainage.

[0044] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0045] (1) In the prior art, detecting the liquid level through a liquid level sensor requires additional hardware resources, which increases the cost of parts. In addition, the measurement is inaccurate when the liquid level shakes. Sensor failure will also cause a series of anode drainage problems, which may lead to a shutdown in severe cases. The present invention is based on a minimum liquid level detection method and system for a gas-water separator in a fuel cell system. It uses an electrically heated drainage solenoid valve on a gas-water separator to judge the liquid level by heating the valve core and comparing the temperature difference, without the need for additional liquid level or pressure sensors. This avoids the cost increase caused by adding sensors, while eliminating the impact of sensor failure on system operation and reducing the risk of system failure.

[0046] (2) The existing method of judging whether the stored water has been drained by a pressure sensor will discharge a certain amount of hydrogen each time the water is drained, which reduces the utilization rate of hydrogen. The drainage cycle correction method and system of the present invention reasonably sets the drainage cycle and uses an electrically heated drainage solenoid valve for heating and temperature monitoring after drainage. When it is judged that the drainage has drained the stored liquid, the drainage judgment value is increased, the interval time between two drainages is increased, and the hydrogen discharge during excessive drainage is reduced; when it is judged that there is still residual liquid after drainage, the drainage judgment value is appropriately reduced to ensure sufficient drainage and not excessive drainage, thereby effectively improving the utilization rate of hydrogen.

[0047] (3) The present invention can accurately determine the minimum liquid level in the gas-water separator without relying on additional sensors, and combined with the drainage cycle correction strategy, the liquid level is always maintained within a reasonable range. The integral weight is set according to the relationship between the working current of the fuel cell stack and the anode drainage volume, the anode drainage volume is accumulated and calculated and compared with the preset drainage judgment value to control the drainage operation, and the drainage judgment value is adjusted in real time according to the temperature change after drainage. This method prevents the liquid level from being too high due to long-term insufficient drainage and affecting the gas-water separation effect, and avoids frequent over-drainage, thereby ensuring the accuracy and stability of the liquid level control and the stable operation of the fuel cell system. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1It is a schematic diagram of the installation structure of the gas-water separator and the electric heating drainage solenoid valve of the present invention.

[0049] Figure 2 It is the integral weight diagram corresponding to different working current density / stack current.

[0050] Figure 3 This is a drainage cycle correction strategy diagram of the present invention.

[0051] Figure numerals: 1-gas-water separator; 11, liquid storage chamber; 2-electric heating drainage solenoid valve; 21-solenoid valve body; 22-heating and temperature measuring components; 23-drainage port; 3-sealing ring. DETAILED DESCRIPTION

[0052] In order to enable those skilled in the art to better understand the technical solution of the present invention, the preferred implementation scheme of the present invention is described below in conjunction with specific embodiments. However, it should be understood that the drawings are only used for exemplary description and cannot be understood as a limitation on this patent. In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The positional relationship described in the drawings is only for exemplary description and cannot be understood as a limitation on this patent.

[0053] like Figure 1 As shown, the present invention utilizes the electric heating drainage solenoid valve 2 equipped with the gas-water separator 1 and the principle of heat transfer, combined with the existing resources in the application scenario, to perform liquid level detection and drainage correction without relying on the auxiliary measurement of sensors such as liquid level / pressure. Among them, the electric heating drainage solenoid valve 2 includes a solenoid valve body 21, and the connection between the solenoid valve body 21 and the gas-water separator 1 is provided with a heating and temperature measuring component 22 for heating and measuring the temperature of the water stored at the bottom of the gas-water separator 1, and a sealing ring 3, and a drainage port 23 is provided at the bottom of the solenoid valve body. The specific structure of the electric heating drainage solenoid valve 2 can be selected conventionally in the art, and the heating component is such as PTC heating ceramics, and the temperature measuring component is such as NTC thermistor.

[0054] Generally, an electric heating drain solenoid valve is provided on the hydrogen gas-water separator of a fuel cell. In a low temperature environment (such as -30℃ or other environments below 0℃), electric heating can be used to melt the ice formed by the liquid water remaining around the valve core to clear the drainage channel. When the gas-water separator is working normally, a certain height of liquid water will accumulate at the bottom of the separator. After heating with the heating component for a certain period of time, due to different liquid levels and different thermal capacities of the system, the temperature measuring element at the valve core detects different changes in thermistor value / temperature rise. By setting a threshold value for resistance value change / temperature rise, it can be determined whether the liquid level in the separator is lower than the design value.

[0055] In particular, when the liquid water at the valve core is completely drained, the temperature rise of heating hydrogen and the temperature rise of heating liquid water will be more different. When the liquid water in the gas-water separator is completely drained, because the difference in thermistor value / temperature rise detected by the above method when there is water and no water at the valve core will be very large, it is easier to use as a standard for liquid level judgment.

[0056] In some examples, the present invention provides a method for detecting a minimum liquid level of a gas-water separator in a fuel cell system, comprising the following steps:

[0057] (1) using the electrically heated drainage solenoid valve 2 installed on the gas-water separator 1 to heat the valve core of the electrically heated drainage solenoid valve 2;

[0058] (2) measuring and recording the initial temperature value at the beginning of heating, and measuring and recording the current temperature value again after heating continues for a period of time, and calculating the temperature difference between the two measurements;

[0059] (3) and comparing the temperature difference with a preset temperature threshold. If the temperature difference is less than the preset temperature threshold, the liquid level in the gas-water separator is higher than the preset minimum liquid level; if the temperature difference is equal to the preset temperature threshold, the liquid level in the gas-water separator is at the preset minimum liquid level; if the temperature difference is greater than the preset temperature threshold, the liquid level in the gas-water separator is lower than the preset minimum liquid level. The preset temperature threshold is the temperature difference of heating water corresponding to the preset minimum liquid level in the gas-water separator under the same conditions.

[0060] In some examples, the present invention provides a minimum liquid level detection system based on a gas-water separator of a fuel cell system, for performing the minimum liquid level detection method, the system comprising:

[0061] A gas-water separator 1, used to separate liquid water carried by the hydrogen outlet of the fuel cell;

[0062] The electric heating drainage solenoid valve 2 is installed on the gas-water separator 1 and is used to perform heating, temperature measurement and drainage operations;

[0063] A control module, used for controlling the heating of the valve core of the electric heating drainage solenoid valve 2;

[0064] The data acquisition and calculation module is used to measure and record the initial temperature value at the beginning of heating, and to measure and record the current temperature value after heating continues for a period of time, and calculate the temperature difference between the two measurements;

[0065] The judgment output module is used to compare the calculated temperature difference with a preset temperature threshold, and judge whether the liquid level in the gas-water separator is higher than, equal to or lower than a preset minimum liquid level according to the comparison result.

[0066] In order to reduce the exhaust loss during over-drainage, the drainage cycle can be corrected by combining the following methods.

[0067] like Figure 2 As shown, by pre-calculating or measuring the relationship between the working current of the battery stack and the anode water discharge, the integral weight η of the water discharge calculation under different working currents of the battery stack is set, that is, η is a function of the working current of the battery stack, η = f(I). So that when the system works with variable load, the cumulative water discharge of the anode in any period of time can be estimated. The cumulative water discharge of the anode in any period of time C = ∫η·dt.

[0068] According to the design of the liquid storage chamber 11 of the gas-water separator 1, different liquid level heights represent different liquid storage volumes. When the liquid level rises to a certain height, drainage should be carried out (to prevent the liquid level from being too high, which will affect the gas-water separation effect). A reasonable drainage height is set, and the water storage volume ξ corresponding to this drainage height is set as the initial value of the drainage judgment value C1. That is, during initialization, C1 = ξ.

[0069] According to the characteristics of the electric heating drain solenoid valve itself, set the heating time t and the temperature difference comparison value T'.

[0070] The values ​​of n, α, and β are set (calibrable) to accommodate the influence of other non-standard quantities on anode drainage, so that water will not accumulate. At the same time, the proportion of excessive drainage / exhaust times is small, thereby improving hydrogen utilization.

[0071] η, ξ, T', t, n, α, β can be calibrated and adjusted. The setting methods of η and ξ have been described in the previous article, and the settings of T', t, n, α, β are introduced in the control logic process description. When the system is running, η, ξ, T', t, n, α, β are constants. C, C1, N are variables when the program is running.

[0072] like Figure 3 As shown in the figure, the specific process of the drainage cycle control strategy is described as follows:

[0073] At the beginning, variables C, C1, and N are initialized first, and the accumulated water volume calculation value C is set to 0, that is, 0 is assigned to variable C. The drainage judgment value C1 is assigned an initial value, C1=ξ; the counter N is set to 0, N=0.

[0074] The accumulated water volume integral value is calculated continuously. When the calculated accumulated water volume C ≥ threshold C1, drainage is performed immediately. When draining, the electric heating drainage solenoid valve is opened. The duration of the electric heating drainage solenoid valve opening can be set according to the anode outlet pressure value of the battery stack at this time. For the same drainage volume, when the anode outlet pressure is high, that is, the pressure in the gas-water separator is high, the drainage speed is also faster. After draining the same volume of water, the corresponding drainage time is different under different pressures.

[0075] When the drain solenoid valve is opened, the accumulated water volume calculation value C should be reset to 0 and a new round of integral calculation should be started.

[0076] At the end of drainage, the heating component in the electric heating drainage solenoid valve is turned on, and the temperature value T1 at that time is recorded. After heating for t time, the temperature value T2 at that time is read again, and the temperature difference ΔT=T2-T1 is calculated. When there are different liquid levels in the liquid storage chamber, the heat capacity when heated is different, and the temperature rise ΔT after the same heating time t will be different. The lower the liquid level in the liquid storage chamber, the higher the temperature rise after the same heating time. In particular, when the liquid in the liquid storage chamber is drained, the maximum temperature rise can be obtained for the same heating time. A value T' slightly smaller than this temperature rise can be set as the threshold. When the temperature rise exceeds the threshold, it is considered that the water in the liquid storage chamber has been completely drained in this drainage. The selection of heating time t is related to the volume of the liquid storage chamber, etc., and the time t cannot be longer than the minimum drainage interval. For example, under certain working conditions, drainage must be started once in a minimum of 10s. If t≥10s, it will cause the next drainage to occur when the previous judgment has not been completed, making the program invalid. If the t time is too long, the liquid will accumulate during the judgment process, causing the ΔT test value to be too small. However, the setting time of t cannot be too short. A short heating time may cause the relative error of ΔT to be too large. T' is set after the t value is set. T' should be less than the minimum temperature rise value after heating for t time after the stored liquid is completely drained (during the heating time t, because there is new water accumulated at the valve core, the minimum temperature rise is obtained at the maximum current density).

[0077] If the ΔT of that time is less than T', it can be considered that after drainage, there is still a certain amount of liquid left in the liquid storage chamber. In order to prevent more and more liquid from being retained under special working conditions or due to deviations in the calibration value. After each drainage, as long as ΔT is still less than T', the threshold of drainage judgment is reduced a little bit C1 = C1-β, so that the water can be drained after a certain drainage. By counting the number of times the threshold is reduced by a counter, it can assist in completing the fault diagnosis of the drain valve. Because if the drain valve fails, no matter how the opening interval of the drain valve is shortened, the retained liquid cannot be drained. This is the reason why the drainage fault is reported when N ≥ the preset fault value n.

[0078] If the ΔT≥T' of this time, it is considered that the stored liquid has been drained out of this drainage. In order to prevent the continuous drainage of water, which leads to the discharge of hydrogen and the reduction of hydrogen utilization rate. When ΔT≥T', the judgment value C1=C1+α should be updated to increase the drainage threshold and increase the interval time between two drainages. At the same time, the counter N should be reset to 0, and the number of times the drainage threshold C1 is reduced should be counted again. During the calibration process, the setting of the β value can be adjusted according to the count value N of the counter when ΔT≥T' of this time. When the drainage judgment threshold is reduced to C1=C1-β and updated to 5 to 8 cycles, the water can be drained once; at the same time, the α value can be set to 5 to 8 times the β value, so as to ensure the stability of the drainage cycle, and the preset fault value n should be set to be greater than the α / β value.

[0079] In some examples, the present invention provides a drainage cycle correction system based on a gas-water separator of a fuel cell system, for executing the drainage cycle correction method, the system comprising:

[0080] A gas-water separator 1, used to separate liquid water carried by the hydrogen outlet of the fuel cell;

[0081] The electric heating drainage solenoid valve 2 is installed on the gas-water separator 1 and is used to perform heating, temperature measurement and drainage operations;

[0082] An integral weight setting module, which sets the integral weight of the water discharge under different working currents according to the relationship between the working current of the fuel cell stack and the anode water discharge;

[0083] A cumulative water discharge calculation module, which calculates the anode water discharge C within a period of time according to the integral weight setting module;

[0084] A drainage control module, which compares the accumulated drainage volume C with a preset drainage judgment value C1, and controls the electric heating drainage solenoid valve to perform drainage operation when the accumulated drainage volume C reaches or exceeds the drainage judgment value C1, and resets the accumulated drainage volume C during drainage;

[0085] The drainage effect monitoring module controls the electric heating drainage solenoid valve to perform heating and temperature monitoring at the end of drainage, and adjusts the subsequent drainage judgment value C1 according to the temperature change to avoid insufficient or excessive drainage.

[0086] In summary, the amount of water discharged from the anode of the fuel cell system is affected by multiple factors such as the working current of the stack, the working temperature of the stack, and the ambient temperature. After the hydrogen gas-water separator separates the liquid water, it needs to be discharged in a timely and quantitative manner. When the liquid level sensor is not set and the drainage is only based on the calibrated drainage cycle, it is difficult to ensure that the drainage is appropriate under all operating conditions because the calibration amount is limited. That is, it may cause failures such as over-drainage (hydrogen is discharged during drainage) or insufficient drainage (causing more and more liquid water to accumulate) in a certain period of time. When a liquid level sensor is set, the system cost will be increased, and the risk of system failure will also be increased due to the failure of the liquid level sensor. The present invention completes the judgment of the lowest liquid level in the gas-water separator without adding additional sensors, and only uses the electric heating drainage solenoid valve equipped with the gas-water separator, and combines the correction strategy of the drainage cycle to ensure that there will be no failure due to insufficient drainage, and no exhaust will occur every time drainage is performed, thereby improving the hydrogen rate.

[0087] According to the description and drawings of the present invention, those skilled in the art can easily use the minimum liquid level detection method and drainage cycle correction method and system based on the gas-water separator of the fuel cell system of the present invention, and can produce the positive effects recorded in the present invention.

[0088] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for detecting the minimum liquid level of a gas-water separator in a fuel cell system, characterized in that: The steps include: The valve core of the electric heating drainage solenoid valve installed on the gas-water separator is heated; Measure and record the initial temperature value at the beginning of heating. After heating continues for a period of time, measure and record the current temperature value again, and calculate the temperature difference between the two measurements. and comparing the temperature difference with a preset temperature threshold. If the temperature difference is less than the preset temperature threshold, the liquid level in the gas-water separator is higher than a preset minimum liquid level; If the temperature difference is equal to the preset temperature threshold, the liquid level in the gas-water separator is at a predetermined minimum liquid level; If the temperature difference is greater than the preset temperature threshold, the liquid level in the gas-water separator is lower than the predetermined minimum liquid level.

2. The method for detecting the minimum liquid level of a gas-water separator in a fuel cell system according to claim 1, characterized in that: The preset temperature threshold is a temperature difference of water corresponding to a predetermined minimum liquid level in the gas-water separator when heated under the same conditions.

3. The method for detecting the minimum liquid level of a gas-water separator in a fuel cell system according to claim 1, characterized in that: The electric heating drainage solenoid valve includes a solenoid valve body. The connection between the solenoid valve body and the gas-water separator is provided with a heating and temperature measuring component for heating and measuring the temperature of the water stored at the bottom of the gas-water separator, and a sealing ring. A drainage port is provided at the bottom of the solenoid valve body.

4. A minimum liquid level detection system based on a gas-water separator of a fuel cell system, characterized in that: For executing the minimum liquid level detection method according to any one of claims 1 to 3, the system comprises: A gas-water separator, used to separate liquid water carried by the hydrogen outlet of the fuel cell; An electric heating and drainage solenoid valve is installed on the gas-water separator and is used to perform heating, temperature measurement and drainage operations; A control module, used for controlling the heating of the valve core of the electric heating drain solenoid valve; The data acquisition and calculation module is used to measure and record the initial temperature value at the beginning of heating, and to measure and record the current temperature value after heating continues for a period of time, and calculate the temperature difference between the two measurements; The judgment output module is used to compare the calculated temperature difference with a preset temperature threshold, and judge whether the liquid level in the gas-water separator is higher than, equal to or lower than a preset minimum liquid level according to the comparison result.

5. A drainage cycle correction method based on a gas-water separator of a fuel cell system, characterized in that: The steps include: According to the relationship between the working current of the fuel cell stack and the anode water discharge, the water discharge integral weight under different working currents is set; The anode drainage volume C within a period of time is accumulated and calculated, and compared with a preset drainage judgment value C1, and a drainage operation is performed when the accumulated drainage volume C reaches or exceeds the drainage judgment value C1; After drainage, the electric heating drainage solenoid valve installed on the gas-water separator is used for heating and temperature monitoring, and the subsequent drainage judgment value C1 is adjusted according to the temperature change to avoid insufficient drainage or excessive drainage.

6. The method for correcting the drainage cycle based on the gas-water separator of the fuel cell system according to claim 5, characterized in that: The relationship between the stack operating current and the anode discharge is as follows: η=f(I) C=∫η·dt In the above formula, η is the integral weight of the water discharge calculation under different fuel cell stack operating currents, I is the fuel cell stack operating current, and C is the cumulative water discharge of the anode within any period of time.

7. The drainage cycle correction method based on the gas-water separator of the fuel cell system according to claim 5 is characterized in that: When the electric heating drain solenoid valve is opened to drain water, the accumulated drainage volume C should be reset to 0 and a new round of integral calculation should be started.

8. The method for correcting the drainage cycle based on the gas-water separator of the fuel cell system according to claim 5, characterized in that: When drainage is finished, the electric heating drainage solenoid valve is turned on for heating and temperature monitoring, and the temperature value T1 at that time is recorded. After heating for a period of time, the temperature value T2 is read again, and the temperature difference ΔT=T2-T1 is calculated; When the temperature difference ΔT<T', it is considered that there is still a certain amount of liquid left in the liquid storage chamber after drainage. At this time, the drainage judgment value C1=C1-β should be reduced, and the number of times the threshold value is reduced N should be counted through the counter. When N≥preset fault value n, a drainage fault is reported; When the temperature difference ΔT≥T', it is considered that the current drainage has drained all the stored liquid. At this time, the drainage judgment value C1=C1+α should be increased, and the interval time between two drainages should be increased. At the same time, the number of times the counter statistical threshold is reduced N is reset to 0, and the number of times the drainage judgment value C1 is reduced is restarted.

9. The method for correcting the drainage cycle based on the gas-water separator of the fuel cell system according to claim 1, characterized in that: During the calibration process, the setting of β value is adjusted according to the count value N of the counter when ΔT≥T' at that time, so as to ensure that when the drainage judgment value is reduced to C1=C1-β and updated to 5~8 cycles, the water can be drained once; at the same time, the α value is set to 5~8 times the β value, and the preset fault value n should be set greater than the α / β value.

10. A drainage cycle correction system based on a gas-water separator of a fuel cell system, characterized in that: For executing the drainage cycle correction method according to any one of claims 5 to 9, the system comprises: A gas-water separator, used to separate liquid water carried by the hydrogen outlet of the fuel cell; An electric heating and drainage solenoid valve is installed on the gas-water separator and is used to perform heating, temperature measurement and drainage operations; An integral weight setting module, which sets the integral weight of the water discharge under different working currents according to the relationship between the working current of the fuel cell stack and the anode water discharge; A cumulative water discharge calculation module, which calculates the anode water discharge C within a period of time according to the integral weight setting module; A drainage control module, which compares the accumulated drainage volume C with a preset drainage judgment value C1, and controls the electric heating drainage solenoid valve to perform drainage operation when the accumulated drainage volume C reaches or exceeds the drainage judgment value C1, and resets the accumulated drainage volume C during drainage; The drainage effect monitoring module controls the electric heating drainage solenoid valve to perform heating and temperature monitoring at the end of drainage, and adjusts the subsequent drainage judgment value C1 according to the temperature change to avoid insufficient or excessive drainage.

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