CN100530798C - Liquid fuel supplement control system and liquid fuel supplement control method for fuel cell - Google Patents

Abstract

The invention provides a liquid fuel supplement control system and a liquid fuel supplement control method for a fuel cell, which control the system operation temperature of a liquid fuel cell system, and the liquid fuel supplement control system for the liquid fuel cell comprises: a preset working temperature value; a fuel cell system temperature detecting device for detecting the system temperature value of the liquid fuel cell system; a fuel replenishing system, including a storage tank and a liquid delivery device, the liquid delivery device delivering the high-concentration liquid fuel stored in the storage tank to the fuel area to adjust the concentration of the fuel area; and a fuel replenishment control unit having a predetermined fuel replenishment rate; the fuel supplement control unit calculates a temperature difference value according to the system temperature value and a preset working temperature value, then increases or decreases a preset supplement speed value according to the temperature difference value to generate a working supplement speed value, and controls the speed of the fuel supplement system for sending out the liquid fuel according to the working supplement speed.

Description

Fuel cell liquid fuel replenishment control system and liquid fuel replenishment control method

technical field

The present invention relates to a liquid fuel cell system, especially a liquid fuel replenishment control system for a liquid fuel cell and the liquid fuel cell system applied thereto, in particular to a liquid fuel replenishment speed adjusted by detecting the temperature of the liquid fuel in the liquid fuel cell method and device.

Background technique

When the fuel cell is currently in operation, as the system continues to respond to the continuous consumption of fuel, the volume and concentration of the fuel will decrease. In order to make the fuel cell operate in the best state, how to supplement the fuel in an appropriate amount to maintain the concentration In the most suitable range is a very important direction in the research of fuel cell systems.

In order to control the fuel concentration of the system, there are quite a few ways, the most direct method is to directly measure the fuel concentration, and determine the fuel replenishment amount according to the measurement results, such as prior art US6589671B1, US6488837, US2002/076589A1 and WO01/35478, etc. Various measurement methods are used to determine the concentration of methanol and then determine the supplementary amount of methanol or water. In addition, Ballard Power’s patent case US6698278B2 is to bring the measured temperature and current value into an empirical formula to calculate, and the fuel can be obtained. Concentration, and then control the fuel concentration.

FIG. 1 is a block diagram of a conventional fuel cell system 10 . The fuel cell system 10 includes a liquid fuel replenishment control system 11 , a fuel cell stack 111 , a pump 112 and a fuel area 118 . The fuel area 118 stores a liquid fuel. The concentration of the liquid fuel needs to be controlled in the most suitable range, so that the fuel cell can operate in an optimal state. The pump 112 sends the liquid fuel to the anode of the fuel cell stack 111 to react with the anode.

The liquid fuel replenishment control system 11 controls the concentration of liquid fuel in the fuel zone 118 . The liquid fuel supplement control system 11 includes: a concentration detection device 117 , a fuel supplement control unit 115 , and a fuel supplement system 12 .

The concentration detection device 117 detects the concentration value of the liquid fuel in the fuel area 118 . The fuel replenishment control unit 115, according to the concentration value obtained by the concentration detection device 117, and according to the difference between the concentration value and a concentration standard value, adjusts the added amount of methanol replenishment, so as to control the concentration of the liquid fuel in the fuel area 118 to reach the standard value.

The fuel replenishment system 12 includes a storage tank 113 and a liquid delivery device 114 . The liquid conveying device 114 receives the supplementary amount of methanol, and sends the high-concentration liquid fuel stored in the storage tank 113 to the fuel area 118 . In addition, some systems must be designed to include a lower concentration liquid fuel source or a pure water source to adjust the concentration of the liquid fuel in the fuel zone due to the requirement to carry a higher concentration of fuel. Generally speaking, this part of the function will be completed by using the recovered water generated by the reaction at the cathode end of the fuel cell system.

For liquid fuels, such as methanol solution, there are two problems with most of the detection components of its concentration: accuracy and price. In the prior art such as US6589679, another small fuel cell unit is used for concentration measurement, and the measurement accuracy is easily affected by various factors, such as temperature changes, impurities in the liquid, and even component aging. The method of Ballard Power is more informative, but it needs to be adjusted according to different systems in order to adapt to each system of different sizes. It is inconvenient for system control to take such a lot of trouble to get an accurate concentration value.

Contents of the invention

The invention provides a fuel cell liquid fuel replenishment control system, which controls a liquid fuel cell system to operate within a preset working temperature range by adjusting the fuel replenishment speed. The liquid fuel replenishment control system of the liquid fuel cell includes: a preset operating temperature value; a fuel cell system temperature detection device, which detects a system temperature value of the liquid fuel cell system; a fuel replenishment system, which includes a storage tank and a liquid delivery device, the liquid delivery device sends the high-concentration liquid fuel stored in the storage tank to the fuel area to supplement the fuel; and a fuel supplement control unit, which has a preset fuel supplement speed; the fuel The replenishment control unit sends fuel into the fuel area according to the preset fuel replenishment rate, and then calculates a temperature difference value according to the system temperature value and the preset operating temperature value, and then increases the preset replenishment rate value according to the temperature difference value Or reduce it to generate a work replenishment speed value, and then perform fuel replenishment according to the work replenishment speed.

In the liquid fuel replenishment control system of the liquid fuel cell of the present invention, the preset working temperature range is between 30°C and 80°C.

The liquid fuel replenishment control system of the liquid fuel cell according to the present invention includes an ambient temperature detection device to detect an ambient temperature value, and the fuel replenishment control unit adjusts the preset operating temperature value to be 5°C higher than the ambient temperature value above.

In the liquid fuel replenishment control system of the liquid fuel cell of the present invention, the preset fuel replenishment speed is set to be 1-7 times the fuel amount required by the preset output current of the fuel cell.

In the liquid fuel replenishment control system of the liquid fuel cell of the present invention, when the temperature difference is greater than an upper limit of the temperature difference, the fuel replenishment control unit generates the work replenishment speed value after reducing the preset speed value; and when the temperature difference value is less than a temperature difference lower limit, the fuel replenishment control unit increases the preset speed value to generate the working replenishment speed value.

In the liquid fuel replenishment control system of the liquid fuel cell of the present invention, the upper limit of the temperature difference is less than 20°C.

In the liquid fuel replenishment control system of the liquid fuel cell of the present invention, the upper limit of the temperature difference is 10°C.

In the liquid fuel replenishment control system of the liquid fuel cell of the present invention, the lower limit of the temperature difference is greater than -20°C.

In the liquid fuel supplement control system of the liquid fuel cell of the present invention, the lower limit of the temperature difference is -10°C.

A liquid fuel replenishment control method, which uses a liquid delivery device in a fuel replenishment system and a storage tank for storing high-concentration liquid fuel, and changes the storage capacity in a fuel area of a liquid fuel cell system by adjusting the delivery speed of the liquid delivery device. The concentration of the liquid fuel is used to control a liquid fuel cell system to operate within a preset operating temperature range; the liquid fuel replenishment control method includes: setting a preset replenishment speed value; setting a preset operating temperature value; detecting A system temperature value of the liquid fuel cell system; calculate a temperature difference value according to the preset operating temperature value and the system temperature value, and then increase or decrease the preset replenishment speed value according to the temperature difference value to generate a work replenishment Speed value, and then carry out fuel replenishment according to the work replenishment speed.

The liquid fuel replenishment control method of the present invention includes detecting an ambient temperature value, and setting a preset working temperature value higher than the ambient temperature by more than 5°C.

In the liquid fuel replenishment control method of the present invention, the preset fuel replenishment speed is further set to be 1-7 times the fuel amount required by the preset output current of the fuel cell.

The liquid fuel replenishment control method of the present invention further includes: setting an upper limit of temperature difference and a lower limit of temperature difference; when the temperature difference is within the upper and lower limits of the temperature difference, no Job replenishment speed value adjustments.

In the liquid fuel replenishment control method of the present invention, the upper limit of the temperature difference is less than 20°C.

In the liquid fuel replenishment control method of the present invention, the upper limit of the temperature difference is 10°C.

In the liquid fuel replenishment control method of the present invention, the lower limit of the temperature difference is greater than -20°C.

In the liquid fuel replenishment control method of the present invention, the lower limit of the temperature difference is -10°C.

The fuel cell liquid fuel replenishment control system and liquid fuel replenishment control method of the present invention use the measured fuel temperature as a control parameter to adjust the amount of high-concentration methanol fuel replenishment, thereby maintaining stable operation of the system.

Description of drawings

FIG. 1 is a block diagram of a conventional fuel cell system 10;

FIG. 2 is a block diagram of a fuel cell system 20 applying an embodiment of the present invention;

FIG. 3 is a schematic diagram of a logic judgment mechanism.

Detailed ways

The characteristics of liquid fuel cells are: when the concentration of liquid fuel is too low, the membrane electrode group cannot discharge enough electricity. At this time, the phenomenon of liquid fuel reaction permeation (crossover) membrane electrode group is also very low. The temperature is about the same. As the concentration increases, the discharge capacity increases. At this time, with the release of reaction heat and the increase in the amount of liquid fuel reacting and penetrating into the cathode, the liquid fuel will be oxidized on the cathode side. At this time, a large amount of heat will be released. The overall system The temperature increases correspondingly; in this way, a corresponding temperature difference between the system and the environment can be obtained as a warning signal that the concentration is too low or too high; when the concentration keeps rising, the temperature of the whole system also keeps rising correspondingly. When the concentration of the measurable system operates stably at a certain value, the difference between the temperature of the system and the ambient temperature at this time is taken as the upper limit. That is, if the temperature difference exceeds the upper limit, it means that the concentration is too high. At this time, the replenishment amount of high-concentration liquid fuel must be reduced; if the temperature difference is too low, the replenishment amount of high-concentration liquid fuel must be increased.

An embodiment of the liquid fuel replenishment control method of the liquid fuel cell of the present invention is: first set a preset replenishment speed, and the preset value is the maintenance rate per unit time when the liquid fuel cell system is at a standard concentration and connected to a standard load. The amount of high-concentration liquid fuel that needs to be supplemented by the standard concentration includes the fuel demand value and the fuel penetration amount under preset operating conditions. Generally speaking, the preset fuel replenishment speed can be set as 1-7 times of the fuel amount required by the preset output current of the fuel cell.

Then a temperature value of a fuel region inside the liquid fuel cell is detected. A temperature difference value is calculated according to the temperature value of the fuel area and a preset working temperature value, and a working replenishing speed value is output after increasing or decreasing the preset replenishing speed in a predetermined manner according to the temperature difference value. The preset operating temperature value can be set between 30° C.-80° C. according to the operating state of the fuel cell.

Liquid fuel cells provide a fuel replenishment system, which includes a storage tank and a liquid delivery device. The liquid conveying device is controlled to send the high-concentration liquid fuel stored in the storage tank to the fuel area according to the previously outputted work replenishment speed value.

Since the liquid fuel cell has a relatively large allowable range for concentration changes, an upper limit of the temperature difference and a lower limit of the temperature difference can be further provided; when the temperature difference is greater than the upper limit of the temperature difference, a predetermined The determined method outputs the supplementary frequency value after reducing the preset speed value; and when the temperature difference is less than the lower limit of the temperature difference, the supplementary frequency value is output after increasing the preset speed value in a predetermined method, and when When the temperature difference is between the upper and lower limits, the system performs concentration control with the original fuel replenishment speed value. According to theoretical calculations, the upper limit of the temperature difference between the preset working temperature and the system operating temperature can be up to 20°C, and the lower limit of the temperature difference can be as low as -20°C. According to experiments, when the upper limit and lower limit of the temperature difference between the preset working temperature and the system operating temperature are 10°C and -10°C respectively, the system can be controlled quite stably.

In some cases, if the operating temperature of the fuel cell is too close to the ambient temperature of the fuel cell, the fuel concentration control will be unstable. Therefore, in another embodiment of the present invention, the ambient temperature of the liquid fuel cell system is further detected to obtain an ambient temperature value, and the preset operating temperature value is adjusted to be 5° C. higher than the ambient temperature value.

FIG. 2 is a block diagram of a fuel cell system 20 according to an embodiment of the present invention. The fuel cell system 20 includes a liquid fuel replenishment control system 21 , a fuel cell stack 211 , a pump 212 and a fuel area 218 . The fuel area 218 stores a liquid fuel. The concentration of the liquid fuel needs to be controlled in the most suitable range, so that the fuel cell can operate in an optimal state. The pump 212 sends the liquid fuel to the anode of the fuel cell stack 211 to react with the anode.

Liquid fuel replenishment control system 21 controls the concentration of liquid fuel in fuel zone 218 . The liquid fuel supplement control system 21 includes: a fuel area temperature detection device 217, a fuel supplement control unit 215 and a fuel supplement system 22.

The fuel zone temperature detection device 217 detects a fuel zone temperature inside the fuel zone of the liquid fuel cell system. The refueling control unit 215 has a preset working temperature value. The fuel replenishment control unit 215 subtracts the preset operating temperature value from the fuel zone temperature value to calculate a temperature difference, and increases or decreases the preset speed value in a predetermined manner to generate a working replenishment speed value . The fuel replenishment control unit 215 can receive the voltage value of the temperature detection device through an analog-to-digital conversion circuit and convert it into a temperature reading, and then generate the work replenishment speed value through a subtractor or other logic calculation devices. The preset operating temperature value can be set between 30° C.-80° C. according to the operating state of the fuel cell.

The predetermined method of increasing or decreasing the preset speed value is aimed at calculating the fuel consumption after the fuel cell is operated at a standard load with a fixed concentration of fuel supplied by a measuring instrument for a fixed time, as the "preset speed value" during actual control. Supplement". For example, the default standard replenishment method is 5ml/10min (5ml fuel replenishment every ten minutes), when the temperature is lower than the lower limit, the replenishment speed can be modified to 5ml/5min or 10ml/10min. When the temperature is higher than the upper limit, the replenishment amount can also be reduced in this way, or the replenishment time can be increased.

The fuel replenishment system 22 includes a storage tank 213 and a liquid delivery device 214. The fuel replenishment control unit 215 controls the liquid delivery device 214 to deliver the high-concentration liquid fuel stored in the storage tank 213 to the fuel area 218 according to the replenishment rate.

The fuel replenishment control unit 215 can further set an upper limit of the temperature difference and a lower limit of the temperature difference; The upper limit of temperature difference, after reducing the preset speed value by a predetermined method, outputting the supplementary frequency value; and when the temperature difference is smaller than the lower limit of temperature difference, after increasing the preset speed value by a predetermined method Output this complementary frequency value. According to theoretical calculations, the upper limit of the temperature difference between the preset working temperature and the system operating temperature can be up to 20°C, and the lower limit of the temperature difference can be as low as -20°C. According to experiments, when the temperature difference between the temperature of the fuel zone and the preset working temperature is 10°C and -10°C respectively at the upper limit and lower limit, the concentration control can still be performed stably.

The fuel replenishment control unit 215 may further include an ambient temperature detection device 216 for detecting an ambient temperature value of the environment where the liquid fuel cell is located. The refueling control unit 215 receives the ambient temperature value, and adjusts the preset operating temperature value to be 5° C. higher than the ambient temperature value as needed.

FIG. 3 is a schematic diagram of a logic judgment mechanism. The liquid fuel replenishment control method of the present invention mainly includes the following steps: first, measure the temperature signal by a temperature sensor; then, perform A/D signal conversion, and convert the measured temperature signal into a digital signal; then, judge The size of the temperature difference (ΔT), adjust the fuel replenishment amount according to the temperature difference, that is, increase or decrease the preset replenishment speed value to generate a working replenishment speed value; finally, output the control signal to the operating pump (PUMP), The speed at which the fuel replenishment system sends out liquid fuel is controlled according to the work replenishment speed.

According to the method and device provided by the present invention, the concentration control of the liquid fuel in the liquid fuel system can be easily achieved. The most obvious and easily measurable physical phenomenon when the liquid fuel cell is discharged is the change of the system temperature besides the current and voltage. As long as the temperature value of the reacting fuel in the system is measured, the current state of the system can be known. The invention uses the measured fuel temperature value as a control parameter to adjust the amount of high-concentration methanol fuel replenishment, thereby maintaining a stable operation of the system.

The fuel cell liquid fuel replenishment control system and the liquid fuel replenishment control method described in the present invention are also applicable to standard fuel cell systems generally equipped with cathode generated water recovery systems and condensers.

Although the present invention has been described above through preferred embodiments, the preferred embodiments are not intended to limit the present invention. Those skilled in the art should be able to make various changes and supplements to the preferred embodiment without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention is subject to the scope of the claims.

A brief description of the symbols in the drawings is as follows:

10, 20: Fuel cell system

11, 21: Liquid fuel replenishment control system

111, 211: fuel cell stack

112, 212: pump

118, 218: fuel area

117: Concentration detection device

216: Ambient temperature detection device

217: Fuel zone temperature detection device

115, 215: fuel replenishment control unit

12, 22: Fuel replenishment system

113, 213: storage tank

114, 214: liquid delivery device

Claims (17)

1. A fuel cell liquid fuel replenishment control system, characterized in that, by adjusting the fuel replenishment speed, a liquid fuel cell system is controlled to operate within a preset operating temperature range, and the liquid fuel cell replenishment control system of the liquid fuel cell includes : a preset working temperature value; A fuel cell system temperature detection device, which detects a system temperature value of the liquid fuel cell system; A fuel replenishment system, which includes a storage tank and a liquid delivery device, the liquid delivery device sends the high-concentration liquid fuel stored in the storage tank to the fuel area to supplement the fuel; and A fuel supplement control unit, which has a preset fuel supplement speed; the fuel supplement control unit delivers fuel into the fuel area according to the preset fuel supplement speed, and then calculates a temperature difference based on the system temperature value and the preset operating temperature value value, and then increase or decrease the preset replenishment speed value according to the temperature difference to generate a working replenishment speed value, and then perform fuel replenishment according to the working replenishment speed. 2 . The fuel cell liquid fuel replenishment control system according to claim 1 , wherein the preset operating temperature range is between 30° C. and 80° C. 3. The fuel cell liquid fuel replenishment control system according to claim 1, characterized in that it includes an ambient temperature detection device to detect an ambient temperature value, and the fuel replenishment control unit adjusts the preset operating temperature value to be relatively The ambient temperature value is higher than 5°C. 4. The fuel cell liquid fuel replenishment control system according to claim 1, wherein the preset fuel replenishment speed is set to be 1 to 7 times the fuel amount required by the preset fuel cell output current. 5. The fuel cell liquid fuel replenishment control system according to claim 1 or 3, wherein when the temperature difference is greater than an upper limit of the temperature difference, the fuel replenishment control unit generates the operation after reducing the preset speed value a replenishment speed value; and when the temperature difference is less than a temperature difference lower limit, the fuel replenishment control unit increases the preset speed value to generate the working replenishment speed value. 6. The fuel cell liquid fuel replenishment control system according to claim 5, characterized in that the upper limit of the temperature difference is less than 20°C. 7. The fuel cell liquid fuel replenishment control system according to claim 6, wherein the upper limit of the temperature difference is 10°C. 8. The fuel cell liquid fuel replenishment control system according to claim 5, wherein the lower limit of the temperature difference is greater than -20°C. 9. The fuel cell liquid fuel replenishment control system according to claim 8, characterized in that the lower limit of the temperature difference is -10°C. 10. A liquid fuel replenishment control method, characterized in that it uses a liquid delivery device in a fuel replenishment system and a storage tank for storing high-concentration liquid fuel, and changes the delivery speed of a liquid fuel cell system by adjusting the delivery speed of the liquid delivery device. The concentration of the liquid fuel stored in a fuel zone, so as to control the operation of a liquid fuel cell system in a preset working temperature range; the liquid fuel replenishment control method includes: Set a preset replenishment speed value; Setting a preset working temperature value; detecting a system temperature value of the liquid fuel cell system; Calculate a temperature difference value according to the preset working temperature value and the system temperature value, and then increase or decrease the preset replenishment speed value according to the temperature difference value to generate a working replenishment speed value, and then perform fuel according to the working replenishment speed supplement. 11 . The liquid fuel replenishment control method according to claim 10 , further comprising detecting an ambient temperature value and setting a preset working temperature value higher than the ambient temperature by more than 5° C. 12 . 12 . The liquid fuel replenishment control method according to claim 10 , wherein the preset fuel replenishment speed is further set to be 1 to 7 times the fuel amount required by the preset output current of the fuel cell. 13 . 13. The liquid fuel replenishment control method according to claim 10 or 11, further comprising: Setting a temperature difference upper limit and a temperature difference lower limit; When the temperature difference is within the upper and lower limits of the temperature difference, the adjustment of the work replenishment speed value is not performed. 14. The liquid fuel replenishment control method according to claim 13, characterized in that the upper limit of the temperature difference is less than 20°C. 15. The liquid fuel replenishment control method according to claim 14, characterized in that the upper limit of the temperature difference is 10°C. 16. The liquid fuel replenishment control method according to claim 13, characterized in that the lower limit of the temperature difference is greater than -20°C. 17. The liquid fuel replenishment control method according to claim 16, characterized in that the lower limit of the temperature difference is -10°C.

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