Air-cooled fuel cell low-power operation management method

Abstract

The present application relates to the technical field of fuel cell control system, and more particularly to a kind of air-cooled fuel cell low-power operation management method.The management method ensures that air-cooled stack works at lower power as far as possible under the condition of meeting demand.At the same time, it can reduce the noise generated by work, and improve the reliability requirements of hardware resources, so that it has higher endurance journey, lower cost and better reliability at lower cost.The management method can reduce the demand for instantaneous stability of DCDC by delaying effect, giving sufficient DCDC stabilization time, giving sufficient time for DCDC self-precharge, preventing problems such as hardware damage caused by instantaneous overload.

Description

TECHNICAL FIELD

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

[0002] The wind-cooled fuel cell is a power generation device, which can be used in fuel cell electric power-assisted vehicles in the field of vehicle-mounted devices. The fuel cell electric power-assisted vehicle can realize a mileage of more than 100 kilometers under the condition of hydrogen storage of only 100 g, and has no carbon emission in the whole process, which is an ideal clean power.

[0003] However, the wind-cooled fuel cell system in the prior art has problems of serious energy waste, large noise, high requirement for hardware, insufficient system protection strategy and the like. SUMMARY

[0004] Therefore, the present application provides a wind-cooled fuel cell low-power operation management method.

[0005] The present application provides a wind-cooled fuel cell low-power operation management method. The wind-cooled fuel cell system comprises a wind-cooled fuel cell stack, a hydrogen tank, an air inlet valve, an air outlet valve, a fan and a DCDC. The air inlet valve is installed at a hydrogen air inlet of the wind-cooled fuel cell stack, the air outlet valve is installed at a hydrogen air outlet of the wind-cooled fuel cell stack, and the method comprises the following steps.

[0006] S1, when the whole vehicle is started, the whole vehicle controller determines whether to start the wind-cooled fuel cell system according to the SOC value of the lithium battery;

[0007] S2, if the SOC of the lithium battery is greater than 90%, the wind-cooled fuel cell system is not started, at this time, the air inlet valve and the air outlet valve are in a closed state, the fan is not started, and the DCDC enters a forced discharge mode. When the voltage of the wind-cooled fuel cell stack is detected to be lower than 3V, the DCDC exits the forced discharge mode and enters a standby state;

[0008] S3, if the SOC of the lithium battery is greater than or equal to 90% and greater than or equal to 40%, the wind-cooled fuel cell system is started and enters a low-power operation mode;

[0009] S4, if the SOC of the lithium battery is greater than 40%, the wind-cooled fuel cell system is started and enters a high-power operation mode;

[0010] S5, when the wind-cooled fuel cell system is in the high-power operation mode, the whole vehicle controller monitors the SOC value of the lithium battery in real time. If the SOC of the lithium battery is greater than or equal to 90% and greater than or equal to 40%, the low-power operation mode is entered, and S3 is executed.

[0011] S6, when the air-cooled fuel cell system is in low-power operation, the vehicle controller monitors the lithium battery SOC value in real time, and when the battery SOC > 90%, the air-cooled fuel cell system enters the closed state.

[0012] Further, in S3, the low-power operation mode of the air-cooled fuel cell system is:

[0013] S31, the fan is started and loaded to 40% of the full speed value of the fan for operation;

[0014] S32, the inlet valve and the exhaust valve are opened at the same time and purged for 3s, and then the hydrogen exhaust valve enters the circulation mode

[0015] S33, monitor the output voltage value of the air-cooled stack, if the output voltage value of the air-cooled stack > 20V, DCDC enters the running mode, that is, after detecting the output voltage value of the air-cooled stack for 3s, DCDC is pre-charged and performs the pre-charging operation for 3s, and then DCDC is loaded to the target power W1.

[0016] If the output voltage of the air-cooled stack is ≤20V, DCDC enters the closed or standby state, until the output voltage of the air-cooled stack is > 20V, and the DCDC closed or standby time is ≥30S, then DCDC enters the running mode again.

[0017] Further, in S4, the high-power operation mode of the air-cooled fuel cell system is:

[0018] S41, the fan is started;

[0019] S42, the inlet valve and the exhaust valve are opened at the same time and purged for 3s, and then the hydrogen exhaust valve enters the circulation mode;

[0020] S43, monitor the output voltage value of the air-cooled stack, if the output voltage value of the air-cooled stack > 20V, DCDC enters the running mode, that is, after detecting the output voltage value of the air-cooled stack for 3s, DCDC is pre-charged and performs the pre-charging operation for 3s, and then DCDC is loaded to the target power W2.

[0021] If the output voltage of the air-cooled stack is ≤20V, DCDC enters the closed or standby state, until the output voltage of the air-cooled stack is > 20V, and the DCDC closed or standby time is ≥30S, then DCDC enters the running mode again. At the same time, monitor the current working temperature of the cold air stack, and adjust the speed of the fan according to the current working temperature value.

[0022] Further, the circulation mode of the hydrogen exhaust valve is: the exhaust valve is closed for 8s and opened for 0.1s for circulation work.

[0023] Further, the step of adjusting the fan speed according to the current working temperature value in S43 is:

[0024] (1) Calibration of the linear relationship between the target speed of the fan and temperature:

[0025] 1) Calibration of the rate of change of temperature between 55℃ and 75℃: the rate of change of temperature between 55℃ and 59℃ is recorded as S1, the rate of change of temperature between 60℃ and 64℃ is recorded as S2, the rate of change of temperature between 65℃ and 69℃ is recorded as S3, and the rate of change of temperature between 70℃ and 75℃ is recorded as S4;

[0026] 2) Calibration of the rate of change of speed of the fan from 40% to 100% of the full speed value: 40% to 49%, 50% to 59%, 60% to 69%, 70% to 79%, 80% to 89%, and 90% to 100% are recorded as K1, K2, K3, K4, K5, and K6, respectively;

[0027] 3) Calculation of the slope Kmn of the speed loading of the fan:

[0028] When the temperature is S1 and the rate of change of speed of the fan is K1, the slope K11 of the speed loading of the fan is K11 = S1 / K1;

[0029] When the temperature is S2 and the rate of change of speed of the fan is K1, the slope K21 of the speed loading of the fan is K21 = S2 / K1;

[0030] Similarly, when the temperature is Sn and the rate of change of speed of the fan is Km, the slope Kmn of the speed loading of the fan is Kmn = Sn / Km;

[0031] 4) Calibration of the linear relationship between the target speed of the fan and temperature:

[0032] Let the current speed of the fan under the current working temperature condition be R1 (the corresponding rate of change of speed Km can be obtained according to the current speed), and the target speed be R, then the linear relationship between the target speed of the fan and temperature is:

[0033] R = (1 + Kmn) * R1 (1);

[0034] (2) The FCU determines the current working temperature of the air-cooled battery through the battery temperature sensor;

[0035] (3) If T ≤ 55℃, the speed of the fan is loaded to 40% of the full speed value of the fan for constant-speed operation; if T > 55℃, the target speed R of the fan under the current working temperature can be obtained according to formula (1), at this time, the speed of the fan is loaded to the target speed for operation.

[0036] Further, in S31, W1 = 150w.

[0037] Further, in S43, W2 = 500w.

[0038] Further, in S6, when the air-cooled fuel cell system enters the closed state, the air inlet valve and the air outlet valve are closed, the fan is closed after a delay of 5s, the DCDC enters the forced discharge mode, until the voltage of the air-cooled stack is detected to be lower than 3V, the DCDC exits the forced discharge mode and enters the standby state.

[0039] The technical solution provided by the present application has the beneficial effects that: the present application provides an air-cooled fuel cell small-power operation management method, so that the air-cooled stack works in the best working interval as much as possible, the management method ensures that the air-cooled stack works at a lower power as much as possible under the condition of meeting the demand, while reducing the noise generated by work, and improving the reliability requirement of hardware resources, so that it has a higher endurance journey at a lower cost, a better reliability, the management method gives sufficient time for DCDC stabilization time through the time delay effect, so that it can reduce the instantaneous stabilization requirement of DCDC, give sufficient time for DCDC self-precharge, prevent problems such as hardware damage caused by instantaneous overload, etc. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the present application more clear, the embodiments of the present application will be further described below.

[0041] The present application provides an air-cooled fuel cell small-power operation management method, so that the air-cooled stack works in the best working interval as much as possible, the management method ensures that the air-cooled stack works at a lower power as much as possible under the condition of meeting the demand (the lower the power, the higher the efficiency). At the same time, the noise generated by work can be reduced (the noise source of the air-cooled stack working noise is generally from the fan, when the fan works at a low speed, the noise is low), and the reliability requirement of hardware resources is improved, so that it has a higher endurance journey at a lower cost, a better reliability, the management method gives sufficient time for DCDC stabilization time through the time delay effect, so that it can reduce the instantaneous stabilization requirement of DCDC, give sufficient time for DCDC self-precharge, prevent problems such as hardware damage caused by instantaneous overload, etc.

[0042] An air-cooled fuel cell system small-power operation management method, the air-cooled fuel cell system includes an air-cooled stack, a hydrogen tank, an air inlet valve, an air outlet valve, a fan and a DCDC, wherein the air inlet valve is installed at the hydrogen inlet of the air-cooled stack, the air outlet valve is installed at the hydrogen outlet of the air-cooled stack, and the method comprises the following steps:

[0043] S1, when the vehicle starts, the vehicle controller determines whether to start the air-cooled fuel cell system according to the SOC value of the lithium battery;

[0044] S2, if the lithium battery SOC is greater than 90%, the air-cooled fuel cell system is not started, at this time, the air inlet valve and the air outlet valve are in the closed state, the fan is not started, the DCDC enters the forced discharge mode to consume the stored electric energy on the air-cooled stack, avoid safety problems and protect the air-cooled stack body, when the fuel cell controller detects that the voltage of the air-cooled stack is lower than 3V, the DCDC input relay is disconnected, the forced discharge mode is exited, and the standby state is entered;

[0045] S3, if the lithium battery 90% is greater than or equal to SOC and is greater than or equal to 40%, the air-cooled fuel cell system is started and enters a low-power operation mode, at this time, the fuel cell controller controls the fan to start and load to 40% of the full speed value of the fan to operate, then the air inlet valve and the air outlet valve are opened and purged at the same time for 3s, the hydrogen discharge valve enters the circulation mode, at the same time, the fuel cell controller detects the output voltage value of the air-cooled stack, if the output voltage value of the air-cooled stack is greater than 20V, the DCDC enters the operation mode, that is, after a delay of 3s after detecting the output voltage value of the air-cooled stack, the DCDC input relay is closed, the DCDC starts pre-charging, enters the working state, the DCDC starts pre-charging for 3s, the DCDC output relay is closed, the DCDC enters the actual working state, and is loaded to the target power of 150W to supply power to the whole vehicle; at this time, the heat generation and air demand of the air-cooled fuel cell system are relatively low, and the fan keeps operating at 40% of the full speed value; specifically, the full speed value of the fan is 8000r / min;

[0046] In the power supply process, if the fuel cell controller detects that the output voltage of the air-cooled stack is less than or equal to 20V, the DCDC input relay is immediately disconnected, the DCDC enters the closed or standby state to prevent DCDC under-voltage protection, until the fuel cell controller detects that the output voltage of the air-cooled stack is greater than 20V, and the total closing or standby time of the DCDC input relay is greater than or equal to 30S, then the DCDC input relay is closed again to enter the operation mode to restore power supply to the whole vehicle; wherein, the DCDC is in the closed state, and the lithium battery supplies power to the whole vehicle;

[0047] The hydrogen discharge valve enters the circulation mode: the air outlet valve is closed for 8s and opened for 0.1s to work in circulation;

[0048] S4, if the lithium battery SOC > 40%, the air-cooled fuel cell system starts and enters the high-power operation mode, at this time the fan is opened, the air inlet valve and the air outlet valve are opened at the same time and are purged for 3s, then the hydrogen exhaust valve enters the circulation mode, at the same time, the fuel cell controller detects the air-cooled stack output voltage value, if the air-cooled stack output voltage value > 20V, after a delay of 3S, the DCDC input relay is closed, the DCDC starts pre-charging, enters the working quasi-fitting state, after the DCDC pre-charging for 3S, the DCDC output relay is closed, the DCDC enters the actual working state and is loaded to the target power of 500W to supply power to the vehicle; during the power supply process, if the fuel cell controller detects that the air-cooled stack output voltage ≤ 20V, the DCDC input relay is immediately cut off, the DCDC enters the closed or standby state to prevent DCDC under-voltage protection, and when the fuel cell controller detects that the air-cooled stack output voltage > 20V and the total DCDC input relay closing or standby time ≥ 30S, the DCDC input relay is closed again to enter the running mode to restore power supply to the vehicle; wherein, the DCDC is closed by the lithium battery to supply power to the vehicle;

[0049] During the DCDC loading process, the heat generation and air demand of the air-cooled fuel cell system are relatively high, the fuel cell controller controls the fan to be opened, and the target speed of the fan is loaded according to the current working temperature of the air-cooled stack;

[0050] Wherein, when the air-cooled fuel cell system enters the high-power operation mode, the fan operation model is:

[0051] (1), the linear relationship between the calibrated fan target speed and temperature is:

[0052] (1.1) first calibrate the change rate between 55℃ and 75℃, wherein 55℃ is the target working temperature of the fan control, which is also the optimal temperature of the air-cooled stack, and 75℃ is the limit temperature of the air-cooled stack, which is higher than the point and directly stops; 55℃-59℃ is recorded as S1, 60℃-64℃ is recorded as S2, 65℃-69℃ is recorded as S3, and 70℃-75℃ is recorded as S4; it should be noted that the calculation of the temperature change rate is the prior art;

[0053] (1.2) calibrate the speed change rate of the fan from 40% to 100% of the full speed value, which is recorded as K1, K2, K3, K4, K5 and K6 respectively; it should be noted that the calculation of the speed change rate of the fan is the prior art;

[0054] (1.3) calculate the slope Kmn and of the fan speed loading:

[0055] The slope K11 of the fan speed loading when the temperature is S1 and the fan speed change rate is K1, that is, K11=S1 / K1;

[0056] The slope K21 of the fan speed loading when the temperature is S2 and the fan speed change rate is K1, that is, K21=S2 / K1;

[0057] Similarly, the slope Kmn of the fan speed loading when the temperature is Sn and the fan speed change rate is Km, that is, Kmn=Sn / Km;

[0058] (1.4) Linear relationship between the target fan speed and the temperature:

[0059] It is recorded that the current speed of the fan under the current working temperature condition is R1 (the corresponding speed change rate Km can be obtained according to the current speed), and the target speed is R, and the linear relationship between the target fan speed and the temperature is R=(1+Kmn)*R1.

[0060] (2) The FCU determines the current working temperature T of the air-cooled stack through the stack temperature sensor;

[0061] (3) If T≤55℃, the speed of the fan is loaded to 40% of the full speed value of the fan for constant speed operation; if T>55℃, the target speed R of the fan under the current working temperature can be obtained according to formula (1), and at this time, the speed of the fan is loaded to the target speed for operation controlled by the fuel cell controller;

[0062] The hydrogen discharge valve enters the circulation mode: the exhaust valve is closed for 8S and opened for 0.1s to work in circulation.

[0063] S5, when the air-cooled fuel cell system is in high-power operation, the vehicle controller monitors the SOC value of the lithium battery in real time, if 90%≥SOC≥40%, the low-power operation mode is entered, and S3 is executed.

[0064] S6, when the air-cooled fuel cell system is in low-power operation, the vehicle controller monitors the SOC value of the lithium battery in real time, when the battery SOC>90%, the air-cooled fuel cell system enters the closed state, at this time, the inlet valve is closed, the exhaust valve is also closed, no longer supplies the reaction hydrogen to the air-cooled fuel cell system, the DCDC enters the forced discharge mode to consume the electric energy stored on the air-cooled stack, avoids the safety problem and the air-cooled stack body, at the same time, the fuel cell controller detects the output voltage value of the air-cooled stack, if the output voltage value of the air-cooled stack<3V, the forced discharge mode is exited, the DCDC input relay is disconnected, the standby state is entered, and the fan is closed after a delay of 5S to prevent damage to the stack system caused by high temperature accumulation.

[0065] In this article, the front, back, up, down and other orientation words are defined with the position of the middle part between the parts, just to express the technical solution clearly and conveniently. It should be understood that the use of the orientation words should not limit the scope of the application.

[0066] In the case of no conflict, the above-mentioned embodiments and features in the embodiments can be combined with each other.

[0067] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for low-power operation management of an air-cooled fuel cell, characterized in that, The air-cooled fuel cell system includes an air-cooled stack, a hydrogen cylinder, an inlet valve, an outlet valve, a fan, and a DC-DC converter. The inlet valve is installed at the hydrogen inlet of the air-cooled stack, and the outlet valve is installed at the hydrogen outlet of the air-cooled stack. The system includes the following steps: S1. When the vehicle starts, determine whether to start the air-cooled fuel cell system based on the SOC value of the lithium battery; S2. If the lithium battery SOC is greater than 90%, the air-cooled fuel cell system will not start. At this time, the intake valve and exhaust valve are closed, the fan will not start, and the DC-DC converter will enter the forced discharge mode. When the voltage of the air-cooled fuel cell stack is detected to be lower than 3V, the DC-DC converter will exit the forced discharge mode and enter the standby state. S3. If the lithium battery is at 90% ≥ SOC ≥ 40%, the air-cooled fuel cell system will start and enter a low-power operation mode. S4. If the lithium battery SOC > 40%, the air-cooled fuel cell system will start and enter high-power operation mode. S5. When the air-cooled fuel cell system is running at high power, the SOC value of the lithium battery is monitored in real time. If the SOC value of the lithium battery is 90% ≥ 40%, the system enters the low power operation mode and executes S3. S6. When the air-cooled fuel cell system is running at low power, the SOC value of the lithium battery is monitored in real time. When the battery SOC > 90%, the air-cooled fuel cell system enters the shutdown state. In S4, the high-power operation mode of the air-cooled fuel cell system is as follows: S41, Fan is on; S42. After the intake valve and exhaust valve are opened simultaneously and purged for 3 seconds, the hydrogen discharge valve enters the circulation mode. S43. Monitor the output voltage of the air-cooled fuel cell stack. If the output voltage of the air-cooled fuel cell stack is >20V, the DC-DC converter enters the operating mode. That is, after detecting the output voltage of the air-cooled fuel cell stack, there is a 3-second delay. The DC-DC converter then performs a pre-charge operation. After 3 seconds, the DC-DC converter is loaded to the target power W2. If the output voltage of the air-cooled fuel cell stack is ≤20V, the DC-DC converter enters the off or standby state. When the output voltage of the air-cooled fuel cell stack is >20V and the DC-DC converter is off or in standby mode for ≥30 seconds, the DC-DC converter re-enters the operating mode. At the same time, the current operating temperature of the air-cooled fuel cell stack is monitored, and the fan speed is adjusted according to the current operating temperature value. The hydrogen discharge valve enters the circulation mode by closing the valve for 8 seconds and opening it for 0.1 seconds to perform the circulation operation. The steps for adjusting the fan speed based on the current operating temperature in S43 are as follows: (1) Calibrate the linear relationship between the target fan speed and temperature: 1) The rate of change of the calibrated temperature between 55℃ and 75℃: the rate of change of 55℃-59℃ is denoted as S1, the rate of change of 60℃-64℃ as S2, the rate of change of 65℃-69℃ as S3, and the rate of change of 70℃-75℃ as S4. 2) Calibrate the fan speed change rate from 40% to 100% of full speed: 40%-49%, 50%-59%, 60%-69%, 70%-79%, 80%-89%, and 90%-100% are respectively labeled as K1, K2, K3, K4, K5, and K6; 3) Calculate the slope Kmn of the fan speed loading: Calculate the slope K11 of the fan speed loading when the temperature is S1 and the fan speed change rate is K1, i.e., K11=S1 / K1; Calculate the slope K21 of the fan speed loading when the temperature is S2 and the fan speed change rate is K1, i.e., K21=S2 / K1; Similarly, when the temperature is Sn and the fan speed change rate is Km, calculate the slope Kmn of the fan speed loading, that is, Kmn=Sn / Km; 4) Calibrate the linear relationship between the target fan speed and temperature: Let R1 be the current fan speed and R be the target fan speed under the current operating temperature conditions. Then the linear relationship between the target fan speed and the temperature is: R = (1 + Kmn) * R1 (1); (2) The FCU determines the current operating temperature of the air-cooled fuel cell stack through the fuel cell stack temperature sensor; (3) If T≤55℃, the fan speed is loaded to 40% of the full speed value for constant speed operation; if T>55℃, according to formula (1), the target speed R of the fan at the current working temperature can be obtained. At this time, the fan speed is controlled to be loaded to the target speed for operation.

2. The method for low-power operation management of an air-cooled fuel cell according to claim 1, characterized in that, In S3, the low-power operation mode of the air-cooled fuel cell system is as follows: S31. The fan is turned on and operates at 40% of its full speed. S32. After the intake valve and exhaust valve are opened simultaneously and purged for 3 seconds, the hydrogen discharge valve enters the circulation mode. S33. Monitor the output voltage of the air-cooled fuel cell stack. If the output voltage of the air-cooled fuel cell stack is >20V, the DC-DC converter enters the operating mode. That is, after detecting the output voltage of the air-cooled fuel cell stack, there is a 3-second delay. The DC-DC converter then performs a pre-charge operation for 3 seconds. After that, the DC-DC converter is loaded to the target power W1. If the output voltage of the air-cooled fuel cell stack is ≤20V, the DC-DC converter enters the off or standby state. When the output voltage of the air-cooled fuel cell stack is >20V and the DC-DC converter has been off or in standby mode for ≥30 seconds, the DC-DC converter will enter the operating mode again.

3. The method for low-power operation management of an air-cooled fuel cell according to claim 2, characterized in that, In S31, W1 = 150w.

4. The method for low-power operation management of an air-cooled fuel cell according to claim 1, characterized in that, In S43, W2 = 500w.

5. The method for low-power operation management of an air-cooled fuel cell according to claim 1, characterized in that, In S6, when the air-cooled fuel cell system enters the shutdown state, the intake valve and exhaust valve are closed, the fan is delayed for 5 seconds before being turned off, and the DC-DC converter enters the forced discharge mode. When the voltage of the air-cooled fuel cell stack is detected to be lower than 3V, the DC-DC converter exits the forced discharge mode and enters the standby state.