Fuel cell system and low idle control method thereof

Abstract

The application provides a fuel cell system and a low-idling control method thereof, and belongs to the technical field of fuel cells. The fuel cell system comprises a stack and accessory equipment, the accessory equipment comprises an air compressor, a intercooler, a humidifier, an expander and a regulating valve, the regulating valve comprises a bypass valve and an inlet valve, filtered air enters a cathode input end of the stack in sequence through the air compressor, the intercooler, the humidifier and the inlet valve, a first output end of the intercooler is connected with an input end of the expander through the bypass valve, and the expander rotates coaxially with a motor of the air compressor. The low-idling control method comprises the following steps: controlling the accessory equipment to operate in a minimum power consumption mode, then acquiring a pull current of the stack and an opening degree of the regulating valve; and taking a voltage parameter value of the stack meeting a preset condition as a target, iteratively adjusting the pull current of the stack and the opening degree of the regulating valve, so as to control the fuel cell system in a low-idling mode. The application can realize low-power and high-efficiency operation of the fuel cell system and reduce energy loss.

Description

Technical Field

[0001] This application relates to the field of fuel cell technology, and in particular to a fuel cell system and a low idle speed control method thereof. Background Technology

[0002] Fuel cell vehicles typically include a fuel cell and a power battery. The power battery receives energy generated by the fuel cell during idling to prevent the fuel cell's lifespan from being reduced due to frequent start-stop cycles. To reduce the weight and cost of fuel cell vehicles, the power battery is relatively small, thus requiring the fuel cell to reduce power output during idling to avoid overcharging. Therefore, fuel cell system accessories are usually used to consume the stack's idling power; however, this approach wastes too much energy and the fuel cell system's operating efficiency is low. Summary of the Invention

[0003] The main objective of this application is to propose a fuel cell system and its low idle speed control method, which can achieve low-power, high-efficiency operation of the fuel cell system and reduce energy loss.

[0004] To achieve the above objectives, one aspect of this application proposes a fuel cell system, including a fuel cell stack and auxiliary equipment, wherein the auxiliary equipment includes an air compressor, an intercooler, a humidifier, an expander, and a regulating valve, wherein the regulating valve includes a bypass valve and a stack inlet shut-off valve.

[0005] The input end of the air compressor is used to receive filtered air. The output end of the air compressor is connected to the first input end of the intercooler. The first output end of the intercooler is connected to the first input end of the humidifier. The first output end of the humidifier is connected to the cathode input end of the fuel cell stack via the inlet shut-off valve. The first output end of the intercooler is connected to the input end of the expander via the bypass valve. The expander and the motor of the air compressor rotate coaxially.

[0006] To achieve the above objectives, another aspect of this application proposes a low idle speed control method applied to the aforementioned fuel cell system, the method comprising:

[0007] Control the auxiliary equipment to operate in the preset minimum power consumption mode, and then obtain the load current of the fuel cell stack and the opening degree of the regulating valve;

[0008] With the goal of satisfying the preset conditions for the voltage parameter values ​​of the fuel cell stack, the load current of the fuel cell stack and the opening of the regulating valve are iteratively adjusted;

[0009] The fuel cell system is subjected to low-idle speed control based on the load current of the stack after iterative adjustment and the opening degree of the regulating valve.

[0010] Further, the preset conditions include a first condition, a second condition, and a third condition; the iterative adjustment of the load current of the fuel cell stack and the opening of the regulating valve, with the goal of satisfying the preset conditions for the voltage parameter values ​​of the fuel cell stack, includes:

[0011] Reduce the load current of the fuel cell until the voltage parameter value of the fuel cell is obtained and detected to meet the first condition;

[0012] Adjust the opening of the regulating valve until the voltage parameter value of the fuel cell stack is acquired and detected to meet the second condition;

[0013] The minimum single-cell voltage of the fuel cell stack is acquired in real time and used as the first minimum single-cell voltage;

[0014] If the first minimum single-chip voltage is not adjusted to meet the third condition within the first preset time period, then based on the most recent adjustment of the opening of the regulating valve, the steps are either to return to reducing the load current of the fuel cell until the voltage parameter value of the fuel cell meets the first condition, or to return to adjusting the opening of the regulating valve until the voltage parameter value of the fuel cell meets the second condition.

[0015] If the first minimum single-chip voltage is adjusted to meet the third condition within the first preset time period, then the load current of the stack and the opening degree of the regulating valve after iterative adjustment are determined.

[0016] Furthermore, adjusting the opening degree of the regulating valve includes:

[0017] If the bypass valve is not fully open, increase the opening degree of the bypass valve;

[0018] If the bypass valve is fully open, then reduce the opening of the feed shut-off valve.

[0019] Further, the step of selecting to return to reducing the load current of the fuel cell stack until the voltage parameter value of the fuel cell stack meets the first condition, or returning to adjust the opening of the regulating valve until the voltage parameter value of the fuel cell stack meets the second condition, based on the most recent adjustment of the opening of the regulating valve, includes:

[0020] If the most recent adjustment was to the opening of the infeed shut-off valve, or if the most recent adjustment was to the opening of the bypass valve and the bypass valve was not fully open after the adjustment, then return to the step of reducing the load current of the fuel cell until the voltage parameter value of the fuel cell is obtained and detected to meet the first condition.

[0021] If the most recent adjustment was to the opening of the bypass valve and the bypass valve is fully open after the adjustment, then return to adjusting the opening of the regulating valve until the voltage parameter value of the fuel cell stack is obtained and detected to meet the second condition.

[0022] Further, after performing low-idle speed control on the fuel cell system based on the iteratively adjusted load current of the fuel cell stack and the opening degree of the regulating valve, the process includes:

[0023] Obtain the minimum single-cell voltage of the fuel cell stack and use it as the second minimum single-cell voltage;

[0024] If the second minimum single-cell voltage does not exceed the first preset voltage threshold and the stack entry shut-off valve is not fully open, then increase the opening of the stack entry shut-off valve until the minimum single-cell voltage of the stack is obtained and detected to exceed the first preset voltage threshold.

[0025] The maximum single-cell voltage of the fuel cell stack is obtained and used as the first maximum single-cell voltage;

[0026] If the first maximum single-cell voltage does not exceed the second preset voltage threshold, then the current opening of the stack entry shut-off valve remains unchanged, and the process returns to the step of obtaining the minimum single-cell voltage of the stack and using it as the second minimum single-cell voltage.

[0027] Further, after obtaining the maximum single-cell voltage of the fuel cell stack and using it as the first maximum single-cell voltage, the process includes:

[0028] If the first maximum single-cell voltage exceeds the second preset voltage threshold, the opening of the stack cut-off valve is reduced after the second preset time period until the maximum single-cell voltage of the stack is obtained and detected to not exceed the second preset voltage threshold.

[0029] Obtain the minimum single-cell voltage of the fuel cell stack and use it as the third minimum single-cell voltage;

[0030] If the third minimum single-cell voltage does not exceed the first preset voltage threshold, then return to the step of increasing the opening of the stack cutoff valve until the minimum single-cell voltage of the stack is obtained and detected to exceed the first preset voltage threshold.

[0031] If the third minimum single-cell voltage exceeds the first preset voltage threshold, then the current opening of the stack entry shut-off valve remains unchanged, and the process returns to the step of obtaining the minimum single-cell voltage of the stack and using it as the second minimum single-cell voltage.

[0032] Further, after obtaining the minimum single-cell voltage of the fuel cell stack and using it as the second minimum single-cell voltage, the process includes:

[0033] If the second minimum single-cell voltage does not exceed the first preset voltage threshold, and the stack entry shut-off valve is fully open and the bypass valve is not fully closed, then reduce the opening of the bypass valve until the minimum single-cell voltage of the stack is obtained and detected to exceed the first preset voltage threshold.

[0034] The maximum single-cell voltage of the fuel cell stack is obtained and used as the second maximum single-cell voltage;

[0035] If the second maximum single-cell voltage does not exceed the second preset voltage threshold, then the current opening of the bypass valve remains unchanged, and the process returns to the step of obtaining the minimum single-cell voltage of the fuel cell stack and using it as the second minimum single-cell voltage.

[0036] Further, after obtaining the maximum single-cell voltage of the fuel cell stack and using it as the second maximum single-cell voltage, the process includes:

[0037] If the second maximum single-cell voltage exceeds the second preset voltage threshold, the opening of the bypass valve is increased after a third preset time period until the maximum single-cell voltage of the fuel cell stack is obtained and detected to not exceed the second preset voltage threshold.

[0038] Obtain the minimum single-cell voltage of the fuel cell stack and use it as the fourth minimum single-cell voltage;

[0039] If the fourth minimum single-cell voltage does not exceed the first preset voltage threshold, then return to the step of reducing the opening of the bypass valve until the minimum single-cell voltage of the fuel cell stack exceeds the first preset voltage threshold.

[0040] If the fourth minimum single-cell voltage exceeds the first preset voltage threshold, the current opening of the bypass valve remains unchanged, and the process returns to the step of obtaining the minimum single-cell voltage of the fuel cell stack and using it as the second minimum single-cell voltage.

[0041] Furthermore, after obtaining the minimum single-cell voltage of the fuel cell stack and using it as the second minimum single-cell voltage, the method further includes:

[0042] If the second minimum single-cell voltage does not exceed the first preset voltage threshold, and the infeed shut-off valve is fully open and the bypass valve is fully closed, then the speed of the air compressor is increased to restore the performance of the fuel cell stack. After a fourth preset time period, the process of performing low-idle control on the fuel cell system based on the iteratively adjusted load current of the fuel cell stack and the opening of the regulating valve is returned.

[0043] This application includes at least the following beneficial effects: When the air compressor motor and expander rotate coaxially, by connecting the first output terminal of the intercooler to the input terminal of the expander via a bypass valve, energy is recovered by the expander, thereby reducing energy loss in the air compressor. By first controlling the auxiliary equipment included in the fuel cell system to operate in a preset minimum power consumption mode, and then iteratively adjusting the load current of the fuel cell stack and the opening of the regulating valve until the voltage parameters of the fuel cell stack meet preset conditions, the maximum voltage of a single fuel cell stack is ensured to be limited within a suitable value, preventing catalyst oxidation at high potentials. Simultaneously, by limiting the minimum voltage value, the fuel cell stack is maintained at a high efficiency, achieving low-power, high-efficiency operation of the fuel cell system. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structural composition of a fuel cell system provided in an embodiment of this application;

[0045] Figure 2 This is a schematic flowchart of a low idle speed control method provided in an embodiment of this application;

[0046] Figure 3 yes Figure 2 A flowchart illustrating step S220 in the process;

[0047] Figure 4 This is a schematic diagram of the implementation process of the preset idle point protection strategy provided in the embodiments of this application;

[0048] Figure 5 This is a schematic diagram of the implementation process of the first preset protection strategy provided in the embodiments of this application;

[0049] Figure 6 This is a schematic diagram illustrating the implementation process of the second preset protection strategy provided in the embodiments of this application. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of systems and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.

[0051] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various concepts, but unless otherwise stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the words “if,” “when,” or “in response to a determination” as used herein may be interpreted as “when…” or “when…” or “in response to a determination.”

[0052] As used in this application, the terms "at least one," "multiple," "each," "any," etc., include at least one, two, or more; multiple, two or more; each refers to each of the corresponding multiple; and any refers to any one of the multiple. The terms "comprising" and "having," and any variations thereof, as used in this application, are intended to cover non-exclusive inclusion. For example, a method comprising a series of steps is not necessarily limited to those explicitly listed, but may include other steps inherent to the method that are not explicitly listed; a system comprising a series of units is not necessarily limited to those explicitly listed, but may include other units inherent to the system that are not explicitly listed.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0054] Fuel cell vehicles typically include a fuel cell and a power battery. The power battery receives energy generated by the fuel cell during idling to prevent the fuel cell's lifespan from being reduced due to frequent start-stop cycles. To reduce the weight and cost of fuel cell vehicles, the power battery is relatively small, thus requiring the fuel cell to reduce power output during idling to avoid overcharging. Therefore, fuel cell system accessories are usually used to consume the stack's idling power; however, this approach wastes too much energy and the fuel cell system's operating efficiency is low.

[0055] In view of this, embodiments of this application provide a fuel cell system and a low idling speed control method thereof, which can achieve low-power, high-efficiency operation of the fuel cell system and reduce energy loss.

[0056] Please see Figure 1 , Figure 1 This is a schematic diagram of an optional structural composition of a fuel cell system provided in an embodiment of this application. The fuel cell system includes a stack 110 and auxiliary equipment.

[0057] Specifically, the accessory equipment includes an air compressor 121, an intercooler 122, a humidifier 123, an expander 124, and a regulating valve. The regulating valve includes a bypass valve 125 and a feed shut-off valve 126. The input end of the air compressor 121 is used to receive filtered air. The output end of the air compressor 121 is connected to the first input end of the intercooler 122. The first output end of the intercooler 122 is connected to the first input end of the humidifier 123. The first output end of the humidifier 123 is connected to the cathode input end of the fuel cell stack 110 via the feed shut-off valve 126. The first output end of the intercooler 122 is connected to the input end of the expander 124 via the bypass valve 125. The expander 124 rotates coaxially with the motor of the air compressor 121. The output end of the expander 124 is connected to the atmospheric environment.

[0058] Optionally, the accessory device also includes a first filter 127 and a discharge shut-off valve 128. The input end of the first filter 127 is connected to the atmospheric environment to receive air, and the output end of the first filter 127 is connected to the input end of the air compressor 121. The cathode output end of the fuel cell stack 110 is connected to the second input end of the humidifier 123 through the discharge shut-off valve 128, and the second output end of the humidifier 123 is connected to the input end of the expander 124. In addition, a casing 111 is provided on the outside of the fuel cell stack 110. The output end of the casing 111 is provided with a purge pipe connected to the atmospheric environment, and the input end of the casing 111 is connected to the first output end of the intercooler 122.

[0059] It should be noted that the air compressor 121, intercooler 122, humidifier 123, expander 124, first filter 127, bypass valve 125, inlet shut-off valve 126, and outlet shut-off valve 128 can be part or all of the components of the air supply subsystem, which is used to supply air to the fuel cell stack 110. Specifically, the first filter 127 is used to filter particulate matter from the air; the air compressor 121 is used to deliver air with appropriate pressure and flow rate to the fuel cell stack 110; the intercooler 122 is used to adjust the air temperature to an appropriate value; the humidifier 123 is used to increase the humidity of the air to reduce contact resistance and improve the performance of the fuel cell stack 110; and the expander 124 is used to regulate the pressure on the air side, recover energy from the discharged gas, and improve system efficiency.

[0060] In this application, by connecting the first output end of the intercooler to the input end of the expander via a bypass valve, the expander recovers energy while the motor of the air compressor and the expander rotate coaxially, thereby reducing the energy loss of the air compressor.

[0061] Optionally, the accessory device also includes a hydrogen cylinder 131, an ejector 132, a gas-liquid separator 133, a shut-off valve 134, a proportional valve 135, and a hydrogen discharge / drainage valve 136. The output end of the hydrogen cylinder 131 is connected to the first input end of the ejector 132 via the shut-off valve 134 and the proportional valve 135 in sequence. The output end of the ejector 132 is connected to the anode input end of the fuel cell stack 110. The anode output end of the fuel cell stack 110 is connected to the input end of the gas-liquid separator 133. The first output end of the gas-liquid separator 133 is connected to the second input end of the ejector 132. The second output end of the gas-liquid separator 133 is connected to the atmospheric environment via the hydrogen discharge / drainage valve 136.

[0062] It should be noted that the hydrogen cylinder 131, ejector 132, gas-liquid separator 133, shut-off valve 134, proportional valve 135, and hydrogen discharge / drainage valve 136 can be part or all of the components of the hydrogen supply subsystem, which is used to supply hydrogen to the fuel cell stack 110. The gas-liquid separator 133 is used to separate the circulating gas output from the fuel cell stack 110 into gas and liquid. The ejector 132 is used to transfer the hydrogen received at its first input terminal and the hydrogen processed and output by the gas-liquid separator 133 received at its second input terminal to the fuel cell stack 110 for electrochemical reaction. The hydrogen discharge / drainage valve 136 is used to discharge part of the circulating gas and liquid water through a certain opening and closing cycle to increase the concentration of circulating hydrogen.

[0063] Optionally, the accessory device also includes a second filter 141, a deionizer 142, a radiator 143, a PTC heater 144, an expansion tank 145, a water pump 146, and a three-way valve 147. The input terminals of the radiator 143, the PTC heater 144, and the first input terminal of the expansion tank 145 are all connected to the coolant output terminal of the fuel cell stack 110 and the second output terminal of the intercooler 122. The output terminals of the radiator 143 and the PTC heater 144 are both connected to the three-way valve 147. The input terminal of the water pump 146 is connected to the input terminal of the radiator 143, the output terminal of the radiator 143 is connected to the second input terminal of the expansion tank 145, the input terminal of the deionizer 142 and the input terminal of the water pump 146 are both connected to the output terminal of the expansion tank 145, the output terminal of the deionizer 142 is connected to the input terminal of the water pump 146, the output terminal of the water pump 146 is connected to the input terminal of the second filter 141, and the coolant input terminal of the fuel cell stack 110 and the second input terminal of the intercooler 122 are both connected to the output terminal of the second filter 141.

[0064] It should be noted that the second filter 141, deionizer 142, radiator 143, PTC heater 144, expansion tank 145, water pump 146, and three-way valve 147 can be part or all of the components of the thermal management subsystem, which is used to dissipate heat during the operation of the fuel cell stack 110. Specifically, the second filter 141 is used to filter impurities in the coolant, the deionizer 142 is used to reduce the ion concentration in the coolant to ensure system insulation, the radiator 143 is used to dissipate heat from the flowing coolant, and the heat dissipation efficiency can be improved by installing a fan on the radiator 143, the PTC heater 144 is used to provide auxiliary heating to the coolant during the low-temperature cold start of the fuel cell system, the expansion tank 145 is used to store coolant and remove air bubbles in the water path, and the water pump 146 is used to increase the flow rate of the coolant.

[0065] It should be noted that each pair of interconnected devices in the fuel cell system can be connected by pipelines, and metal pipelines, composite material pipelines, flexible hoses, etc. can be selected according to the actual application scenario. This application does not impose any restrictions on this.

[0066] Please see Figure 2 , Figure 2 This is an optional flowchart illustrating a low idle speed control method provided in an embodiment of this application. The method is applied to the aforementioned fuel cell system and may include, but is not limited to, the following steps S210 to S230:

[0067] Step S210: Control the accessory equipment to operate in the preset minimum power consumption mode, and then obtain the load current of the fuel cell stack and the opening degree of the regulating valve.

[0068] Step S220: With the goal of satisfying the preset conditions for the voltage parameter values ​​of the fuel cell stack, iteratively adjust the load current of the fuel cell stack and the opening of the regulating valve.

[0069] Step S230: Perform low idle speed control on the fuel cell system based on the load current of the stack after iterative adjustment and the opening degree of the regulating valve.

[0070] Steps S210 to S230 as shown in the embodiments of this application first control the auxiliary equipment included in the fuel cell system to operate in a preset minimum power consumption mode, and then iteratively adjust the load current of the stack and the opening of the regulating valve until the voltage parameter value of the stack meets the preset conditions. This can reduce the air intake of the stack and achieve long life, low power and high efficiency operation of the fuel cell system.

[0071] In step S210 of some embodiments, controlling the accessory device to operate in a preset minimum power consumption mode can be understood as controlling some or all of the sub-devices included in the accessory device to operate at their respective preset minimum control parameter values, such as adjusting the speed of the air compressor to a preset minimum value of 30,000 rpm, adjusting the speed of the water pump to a preset minimum value of 2,000 rpm, etc.

[0072] In step S220 of some embodiments, since the fuel cell system is actually a high-power fuel cell system with a large number of stack cells, the voltage parameter values ​​of the stack include the average single-cell voltage, the minimum single-cell voltage, and the maximum single-cell voltage of the stack; wherein, the average single-cell voltage of the stack refers to the average value of all voltages corresponding to all single cells in the stack, the minimum single-cell voltage of the stack refers to the minimum value among all voltages corresponding to all single cells in the stack, and the maximum single-cell voltage of the stack refers to the maximum value among all voltages corresponding to all single cells in the stack.

[0073] In step S220 of some embodiments, the preset condition is based on the voltage parameter value of the fuel cell stack, and includes a first condition, a second condition, and a third condition, which are described in detail below:

[0074] The first condition is used to limit the average single-cell voltage of the stack to be greater than a first preset threshold, the maximum single-cell voltage of the stack to be greater than a second preset threshold, and the minimum single-cell voltage of the stack to be greater than a third preset threshold.

[0075] The second condition is used to limit the average single-cell voltage of the battery stack to be approximately equal to the first preset threshold, the maximum single-cell voltage of the battery stack to be less than or equal to the second preset threshold, and the minimum single-cell voltage of the battery stack to be greater than or equal to the third preset threshold; wherein, a first error allowable range with a small fluctuation amplitude can be set for the first preset threshold, and when the average single-cell voltage of the battery stack falls within the first error allowable range, it is determined that the average single-cell voltage of the battery stack is approximately equal to the first preset threshold;

[0076] The third condition is used to limit the minimum single-cell voltage of the fuel cell stack to be approximately equal to the fourth preset threshold. The fourth preset threshold is the difference between the third preset threshold and the preset adjustment amount. A second error allowable range with a small fluctuation range can be set for the fourth preset threshold. When the minimum single-cell voltage of the fuel cell stack falls within the second error allowable range, it is determined that the minimum single-cell voltage of the fuel cell stack is approximately equal to the fourth preset threshold.

[0077] The first preset threshold is preferably set to 830mV, the second preset threshold is preferably set to 845mV, the third preset threshold is preferably set to 810mV, and the preset adjustment amount is preferably set to 10mV.

[0078] In this application, by using the maximum single-cell voltage of the fuel cell stack as the criterion, catalyst oxidation at high potentials can be prevented after adjusting the load current of the fuel cell stack and the opening of the regulating valve; by using the minimum single-cell voltage of the fuel cell stack as the criterion, the fuel cell stack can be ensured to operate stably at high efficiency after adjusting the load current of the fuel cell stack and the opening of the regulating valve.

[0079] Please see Figure 3 In some embodiments, step S220 may include, but is not limited to, steps S310 to S350:

[0080] Step S310: Reduce the load current of the fuel cell until the voltage parameter value of the fuel cell is obtained and detected to meet the first condition;

[0081] Step S320: Adjust the opening of the regulating valve until the voltage parameter value of the fuel cell stack is acquired and detected to meet the second condition;

[0082] Step S330: The minimum single-cell voltage of the fuel cell stack is acquired in real time and used as the first minimum single-cell voltage to determine whether the first minimum single-cell voltage is adjusted to meet the third condition within a first preset time period, which can be set to 2 minutes; if not, then proceed to step S340; if yes, then proceed to step S350.

[0083] Step S340: Based on the most recent adjustment of the opening of the regulating valve, select to return to step S310 or return to step S320;

[0084] Step S350: Determine the load current of the fuel cell stack and the opening degree of the regulating valve after iterative adjustment.

[0085] In this application, by reasonably adjusting the opening of the regulating valve according to the voltage parameter value of the fuel cell stack in constant current mode, low-power operation of the fuel cell system can be effectively achieved.

[0086] It is understood that the implementation of step S310 above is as follows: the load current of the fuel cell stack is reduced once according to a first preset step size to increase the voltage of a single cell of the fuel cell stack; then the voltage parameter value of the fuel cell stack is obtained and it is determined whether it meets the first condition; if it meets the condition, step S320 is executed; if it does not meet the condition, the load current of the fuel cell stack is reduced once more according to the first preset step size, and the voltage parameter value of the fuel cell stack is obtained and determined again. Preferably, the first preset step size is set to 2A, and preferably, the load current of the fuel cell stack is reduced based on an initial reference value of 20A.

[0087] In step S320 above, the adjustment method for the opening of the regulating valve can include the following:

[0088] (1) If the bypass valve is not fully open, that is, the opening degree of the bypass valve is less than 100%, then increase the opening degree of the bypass valve. At this time, there is no need to adjust the opening degree of the feed shut-off valve.

[0089] (2) If the bypass valve is in the fully open state, that is, the opening degree of the bypass valve is 100%, then reduce the opening degree of the feed shut-off valve.

[0090] Specifically, the opening of the bypass valve can be increased by a second preset step size to reduce the voltage of a single cell in the fuel cell stack due to the decrease in air volume. The second preset step size is preferably set to 10%. The opening of the feed shut-off valve can be decreased by a third preset step size to reduce both the current and voltage of the fuel cell stack due to the decrease in air volume. The third preset step size is preferably set to 10%.

[0091] It is understood that the above-mentioned step S320 is implemented as follows: the opening of the regulating valve is adjusted once according to the preset step size, the voltage parameter value of the fuel cell is obtained and it is determined whether the second condition is met; if it is met, step S330 is executed; if it is not met, the opening of the regulating valve is adjusted once again according to the preset step size and the voltage parameter value of the fuel cell is obtained and determined.

[0092] In this application, by limiting the opening of the bypass valve to 100% before allowing the opening of the infeed shut-off valve to be reduced, and using the bypass valve to connect the expander for bypass gas energy recovery, energy loss can be reduced while reducing the air intake of the fuel cell stack.

[0093] In step S340 above, the method of selecting to return to step S310 or step S320 based on the most recent adjustment of the opening of the regulating valve can include the following:

[0094] (1) If the most recent adjustment was to the opening of the feed shut-off valve, then return to step S310;

[0095] (2) If the most recent adjustment was to the opening of the bypass valve and the bypass valve was not fully open after the adjustment, then return to step S310.

[0096] (3) If the most recent adjustment was to the opening of the bypass valve and the bypass valve is fully open after the adjustment, then return to step S320.

[0097] In this application, considering that the smaller the load current of the fuel cell stack, the smaller the output power of the fuel cell stack, and the higher the individual voltage of the fuel cell stack, while the catalyst inside the fuel cell stack will be oxidized at high potential, resulting in a decrease in the activity of the fuel cell stack and a reduction in the service life of the fuel cell stack, when the fuel cell stack is running at a certain load current, if the voltage parameter value of the fuel cell stack still cannot meet the preset conditions and the bypass valve is in the fully open state, the voltage parameter value of the fuel cell stack can be judged by directly adjusting the opening degree of the inlet shut-off valve. This can avoid unreasonable adjustment of the load current of the fuel cell stack, reduce the output power of the fuel cell stack, and improve the operational safety of the fuel cell stack.

[0098] In step S350 above, the method for determining the load current of the fuel cell stack and the opening degree of the regulating valve after iterative adjustment can include the following:

[0099] The current load current of the fuel cell stack, the current opening degree of the bypass valve, and the current opening degree of the inlet shut-off valve are obtained. The current load current of the fuel cell stack is used as the iteratively adjusted load current of the fuel cell stack, which can be understood as the idle current, and the corresponding power is the idle power. The current opening degree of the bypass valve and the current opening degree of the inlet shut-off valve are directly used as the iteratively adjusted opening degree of the bypass valve and the inlet shut-off valve. It should be noted that the opening degrees of the bypass valve and the inlet shut-off valve after iterative adjustment are generally not zero.

[0100] In some embodiments, the low idle speed control method described above may further include: enabling a preset idle point protection strategy to adaptively adjust the low idle speed control process of the fuel cell system.

[0101] Please see Figure 4 Specifically, the implementation process of this preset idle point protection strategy may include, but is not limited to, the following steps S410 to S470:

[0102] Step S410: Obtain the minimum single-cell voltage of the fuel cell stack and use it as the second minimum single-cell voltage;

[0103] Step S420: Determine whether the second minimum single-chip voltage exceeds the first preset voltage threshold, which is preferably set to 780mV; if it exceeds, return to step S410; if it does not exceed, proceed to step S430.

[0104] Step S430: Determine whether the infeed shut-off valve is in the fully open state, that is, determine whether the opening degree of the infeed shut-off valve is 100%; if yes, proceed to step S440; if no, proceed to step S450.

[0105] Step S440: Determine whether the bypass valve is in the fully closed state, that is, determine whether the opening degree of the bypass valve is 0%; if yes, proceed to step S460; if no, proceed to step S470.

[0106] Step S450: Activate the first preset protection strategy to adaptively adjust the opening degree of the reactor inlet shut-off valve;

[0107] Step S460: Increase the speed of the air compressor to restore the performance of the fuel cell stack, and then return to step S230 after a fourth preset time period, which is preferably set to 10 seconds.

[0108] Step S470: Activate the second preset protection strategy to adaptively adjust the opening degree of the bypass valve.

[0109] In this application, considering that after the fuel cell stack has been running at low speed for a long time, the reaction water may not be discharged in time, which may block the active sites, resulting in insufficient reaction gas volume and degraded single cell performance, the use of a preset idle point protection strategy during the low idle control of the fuel cell system helps to restore the performance of the fuel cell stack and ensure the operational reliability of the fuel cell system.

[0110] Please see Figure 5 In some embodiments, step S450 may include, but is not limited to, the following steps S510 to S550:

[0111] Step S510: Increase the opening of the stack entry shut-off valve until the minimum single-cell voltage of the stack is acquired and detected to exceed the first preset voltage threshold.

[0112] Step S520: Obtain the maximum single-cell voltage of the fuel cell stack and use it as the first maximum single-cell voltage. Then determine whether the first maximum single-cell voltage exceeds the second preset voltage threshold. The second preset voltage threshold is preferably set to 845mV. If it does not exceed the threshold, proceed to step S550. If it exceeds the threshold, proceed to step S530.

[0113] Step S530: After the second preset time period, reduce the opening of the stack cutoff valve until the maximum single-cell voltage of the stack is acquired and detected not to exceed the second preset voltage threshold; wherein, the second preset time period is preferably set to 10 seconds;

[0114] Step S540: Obtain the minimum single-cell voltage of the fuel cell stack and use it as the third minimum single-cell voltage. Then determine whether the third minimum single-cell voltage exceeds the first preset voltage threshold. If it does not exceed the threshold, return to step S510. If it exceeds the threshold, proceed to step S550.

[0115] Step S550: Keep the current opening of the infeed shut-off valve unchanged, and then return to step S410.

[0116] In this application, the operational stability of the fuel cell stack is improved by appropriately adjusting the opening of the stack cut-off valve during the low-idle speed control process.

[0117] It is understood that the above-mentioned step S510 is implemented as follows: the opening degree of the feed stop valve is increased and adjusted once according to the third preset step size, and then the minimum single-cell voltage of the fuel cell is obtained and it is determined whether it exceeds the first preset voltage threshold; if it exceeds, then step S520 is executed; if it does not exceed, then the opening degree of the feed stop valve is increased and adjusted once according to the third preset step size, and then the minimum single-cell voltage of the fuel cell is obtained and determined.

[0118] It is understood that the above-mentioned step S530 is implemented as follows: the current opening degree of the feed stop valve is kept constant within the second preset time period, then the opening degree of the feed stop valve is randomly reduced once, and then the maximum single-cell voltage of the fuel cell stack is obtained and it is determined whether it exceeds the second preset voltage threshold; if it does not exceed, then step S540 is executed; if it exceeds, then the opening degree of the feed stop valve is randomly reduced once more and the maximum single-cell voltage of the fuel cell stack is obtained and determined again.

[0119] Please see Figure 6 In step S470 of some embodiments, the specific implementation process of the second preset protection strategy may include, but is not limited to, the following steps S610 to S650:

[0120] Step S610: Reduce the opening of the bypass valve until the minimum single-cell voltage of the fuel cell stack exceeds the first preset voltage threshold.

[0121] Step S620: Obtain the maximum single-cell voltage of the fuel cell stack and use it as the second maximum single-cell voltage. Then determine whether the second maximum single-cell voltage exceeds the second preset voltage threshold. If it does not exceed the threshold, proceed to step S650. If it does exceed the threshold, proceed to step S630.

[0122] Step S630: Increase the opening of the bypass valve after the third preset time period until the maximum single-cell voltage of the fuel cell stack is acquired and detected to not exceed the second preset voltage threshold; wherein, the third preset time period is preferably set to 10 seconds;

[0123] Step S640: Obtain the minimum single-cell voltage of the fuel cell stack and use it as the fourth minimum single-cell voltage. Then determine whether the fourth minimum single-cell voltage exceeds the first preset voltage threshold. If it does not exceed the threshold, return to step S610. If it exceeds the threshold, proceed to step S650.

[0124] Step S650: Keep the current opening of the bypass valve unchanged, and then return to step S410.

[0125] In this application, the operational stability of the fuel cell stack is improved by appropriately adjusting the opening of the bypass valve during the low-idle speed control process.

[0126] It is understood that the above-mentioned step S610 is implemented as follows: the opening degree of the bypass valve is reduced once according to the second preset step size, the minimum single-cell voltage of the fuel cell stack is obtained and it is determined whether it exceeds the first preset voltage threshold; if it exceeds, step S620 is executed; if it does not exceed, the opening degree of the bypass valve is reduced once again according to the second preset step size and the minimum single-cell voltage of the fuel cell stack is obtained and determined.

[0127] It is understood that the above-mentioned step S630 is implemented as follows: the current opening degree of the bypass valve is kept constant within the third preset time period, then the opening degree of the bypass valve is randomly increased once, and then the maximum single-cell voltage of the fuel cell stack is obtained and it is determined whether it exceeds the second preset voltage threshold; if it does not exceed, then step S640 is executed; if it exceeds, then the opening degree of the bypass valve is randomly increased once more and then the maximum single-cell voltage of the fuel cell stack is obtained and determined.

[0128] This application also provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the aforementioned low idle speed control method. This electronic device can include any smart terminal such as a tablet computer or an in-vehicle computer.

[0129] It is understood that the content of the above method embodiments is applicable to the present device embodiments. The specific functions implemented by the present device embodiments are the same as those implemented by the above method embodiments, and the beneficial effects achieved by the present device embodiments are also the same as those achieved by the above method embodiments.

[0130] The embodiments described above are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. Those skilled in the art will know that with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0131] Those skilled in the art will understand that the technical solutions illustrated in the figures do not constitute a limitation on the embodiments of this application, and may include more or fewer steps than illustrated, or combine certain steps, or different steps. The system embodiments described above are merely illustrative, and some or all of the modules can be selected to achieve the purpose of the embodiments according to actual needs.

[0132] The preferred embodiments of this application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of this application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and spirit of the embodiments of this application shall be within the scope of the claims of this application.

Claims

1. A low idle speed control method, characterized in that, This method is applied to a fuel cell system, which includes a fuel cell stack and auxiliary equipment. The auxiliary equipment includes an air compressor, an intercooler, a humidifier, an expander, and a regulating valve. The regulating valve includes a bypass valve and a stack inlet shut-off valve. The low idle speed control method includes: Control the auxiliary equipment to operate in the preset minimum power consumption mode, and then obtain the load current of the fuel cell stack and the opening degree of the regulating valve; With the goal of satisfying preset conditions for the voltage parameters of the fuel cell stack, the load current of the fuel cell stack and the opening of the regulating valve are iteratively adjusted. The preset conditions include a first condition, a second condition, and a third condition. The first condition limits the average single-cell voltage of the fuel cell stack to be greater than a first preset threshold, the maximum single-cell voltage of the fuel cell stack to be greater than a second preset threshold, and the minimum single-cell voltage of the fuel cell stack to be greater than a third preset threshold. The second condition limits the average single-cell voltage of the fuel cell stack to be approximately equal to the first preset threshold, the maximum single-cell voltage of the fuel cell stack to be less than or equal to the second preset threshold, and the minimum single-cell voltage of the fuel cell stack to be greater than or equal to the third preset threshold. The third condition limits the minimum single-cell voltage of the fuel cell stack to be approximately equal to a fourth preset threshold, where the fourth preset threshold is the difference between the third preset threshold and a preset adjustment amount. Based on the iteratively adjusted load current of the fuel cell stack and the opening degree of the regulating valve, the fuel cell system is subjected to low idle speed control. The iterative adjustment of the load current of the fuel cell stack and the opening of the regulating valve, with the goal of satisfying the voltage parameter values ​​of the fuel cell stack under preset conditions, includes: Reduce the load current of the fuel cell until the voltage parameter value of the fuel cell is obtained and detected to meet the first condition; Adjust the opening of the regulating valve until the voltage parameter value of the fuel cell stack is acquired and detected to meet the second condition; The minimum single-cell voltage of the fuel cell stack is acquired in real time and used as the first minimum single-cell voltage; If the first minimum single-chip voltage is not adjusted to meet the third condition within the first preset time period, then based on the most recent adjustment of the opening of the regulating valve, the steps are either to return to reducing the load current of the fuel cell until the voltage parameter value of the fuel cell meets the first condition, or to return to adjusting the opening of the regulating valve until the voltage parameter value of the fuel cell meets the second condition. If the first minimum single-chip voltage is adjusted to meet the third condition within the first preset time period, then the load current of the stack and the opening degree of the regulating valve after iterative adjustment are determined.

2. The low idle speed control method according to claim 1, characterized in that, Adjusting the opening of the regulating valve includes: If the bypass valve is not fully open, then increase the opening degree of the bypass valve; If the bypass valve is fully open, then reduce the opening degree of the feed shut-off valve.

3. The low idle speed control method according to claim 2, characterized in that, The step of selecting to return to reducing the load current of the fuel cell stack until the voltage parameter value of the fuel cell stack meets the first condition, or to return to adjusting the opening of the regulating valve until the voltage parameter value of the fuel cell stack meets the second condition, based on the most recent adjustment of the opening of the regulating valve, includes: If the most recent adjustment was to the opening of the infeed shut-off valve, or if the most recent adjustment was to the opening of the bypass valve and the bypass valve was not fully open after the adjustment, then return to the step of reducing the load current of the fuel cell until the voltage parameter value of the fuel cell is obtained and detected to meet the first condition. If the most recent adjustment was to the opening of the bypass valve and the bypass valve is fully open after the adjustment, then return to adjusting the opening of the regulating valve until the voltage parameter value of the fuel cell stack is obtained and detected to meet the second condition.

4. The low idle speed control method according to any one of claims 1 to 3, characterized in that, After performing low-idle speed control on the fuel cell system based on the iteratively adjusted load current of the fuel cell stack and the opening degree of the regulating valve, the process includes: Obtain the minimum single-cell voltage of the fuel cell stack and use it as the second minimum single-cell voltage; If the second minimum single-cell voltage does not exceed the first preset voltage threshold and the stack entry shut-off valve is not fully open, then increase the opening of the stack entry shut-off valve until the minimum single-cell voltage of the stack is obtained and detected to exceed the first preset voltage threshold. The maximum single-cell voltage of the fuel cell stack is obtained and used as the first maximum single-cell voltage; If the first maximum single-cell voltage does not exceed the second preset voltage threshold, then the current opening of the stack entry shut-off valve remains unchanged, and the process returns to the step of obtaining the minimum single-cell voltage of the stack and using it as the second minimum single-cell voltage.

5. The low idle speed control method according to claim 4, characterized in that, After obtaining the maximum single-cell voltage of the fuel cell stack and using it as the first maximum single-cell voltage, the process includes: If the first maximum single-cell voltage exceeds the second preset voltage threshold, the opening of the stack cut-off valve is reduced after the second preset time period until the maximum single-cell voltage of the stack is obtained and detected to not exceed the second preset voltage threshold. Obtain the minimum single-cell voltage of the fuel cell stack and use it as the third minimum single-cell voltage; If the third minimum single-cell voltage does not exceed the first preset voltage threshold, then return to the step of increasing the opening of the stack cutoff valve until the minimum single-cell voltage of the stack is obtained and detected to exceed the first preset voltage threshold. If the third minimum single-cell voltage exceeds the first preset voltage threshold, then the current opening of the stack entry shut-off valve remains unchanged, and the process returns to the step of obtaining the minimum single-cell voltage of the stack and using it as the second minimum single-cell voltage.

6. The low idle speed control method according to claim 4, characterized in that, After obtaining the minimum single-cell voltage of the fuel cell stack and using it as the second minimum single-cell voltage, the process includes: If the second minimum single-cell voltage does not exceed the first preset voltage threshold, and the stack entry shut-off valve is fully open and the bypass valve is not fully closed, then reduce the opening of the bypass valve until the minimum single-cell voltage of the stack is obtained and detected to exceed the first preset voltage threshold. The maximum single-cell voltage of the fuel cell stack is obtained and used as the second maximum single-cell voltage; If the second maximum single-cell voltage does not exceed the second preset voltage threshold, then the current opening of the bypass valve remains unchanged, and the process returns to the step of obtaining the minimum single-cell voltage of the fuel cell stack and using it as the second minimum single-cell voltage.

7. The low idle speed control method according to claim 6, characterized in that, After obtaining the maximum single-cell voltage of the fuel cell stack and using it as the second maximum single-cell voltage, the process includes: If the second maximum single-cell voltage exceeds the second preset voltage threshold, the opening of the bypass valve is increased after a third preset time period until the maximum single-cell voltage of the fuel cell stack is obtained and detected to not exceed the second preset voltage threshold. Obtain the minimum single-cell voltage of the fuel cell stack and use it as the fourth minimum single-cell voltage; If the fourth minimum single-cell voltage does not exceed the first preset voltage threshold, then return to the step of reducing the opening of the bypass valve until the minimum single-cell voltage of the fuel cell stack exceeds the first preset voltage threshold. If the fourth minimum single-cell voltage exceeds the first preset voltage threshold, the current opening of the bypass valve remains unchanged, and the process returns to the step of obtaining the minimum single-cell voltage of the fuel cell stack and using it as the second minimum single-cell voltage.

8. The low idle speed control method according to claim 4, characterized in that, After obtaining the minimum single-cell voltage of the fuel cell stack and using it as the second minimum single-cell voltage, the process further includes: If the second minimum single-cell voltage does not exceed the first preset voltage threshold, and the infeed shut-off valve is fully open and the bypass valve is fully closed, then the speed of the air compressor is increased to restore the performance of the fuel cell stack. After a fourth preset time period, the process of performing low-idle control on the fuel cell system based on the iteratively adjusted load current of the fuel cell stack and the opening of the regulating valve is returned.

9. The low idle speed control method according to claim 1, characterized in that, The input end of the air compressor is used to receive filtered air. The output end of the air compressor is connected to the first input end of the intercooler. The first output end of the intercooler is connected to the first input end of the humidifier. The first output end of the humidifier is connected to the cathode input end of the fuel cell stack via the inlet shut-off valve. The first output end of the intercooler is connected to the input end of the expander via the bypass valve. The expander and the motor of the air compressor rotate coaxially.

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